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Ritzel RM, Li Y, Jiao Y, Doran SJ, Khan N, Henry RJ, Brunner K, Loane DJ, Faden AI, Szeto GL, Wu J. Bi-directional neuro-immune dysfunction after chronic experimental brain injury. J Neuroinflammation 2024; 21:83. [PMID: 38581043 PMCID: PMC10996305 DOI: 10.1186/s12974-024-03082-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 03/30/2024] [Indexed: 04/07/2024] Open
Abstract
BACKGROUND It is well established that traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function and that systemic immune changes contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined. METHODS To further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham (i.e., 90 days post-surgery) congenic donor mice into otherwise healthy, age-matched, irradiated CD45.2 C57BL/6 (WT) hosts. Immune changes were evaluated by flow cytometry, multiplex ELISA, and NanoString technology. Moderate-to-severe TBI was induced by controlled cortical impact injury and neurological function was measured using a battery of behavioral tests. RESULTS TBI induced chronic alterations in the transcriptome of BM lineage-c-Kit+Sca1+ (LSK+) cells in C57BL/6 mice, including modified epigenetic and senescence pathways. After 8 weeks of reconstitution, peripheral myeloid cells from TBI→WT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBI→WT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI at 8 weeks and 8 months post-reconstitution showed that longer reconstitution periods (i.e., time post-injury) were associated with increased microgliosis and leukocyte infiltration. Pre-treatment with a senolytic agent, ABT-263, significantly improved behavioral performance of aged C57BL/6 mice at baseline, although it did not attenuate neuroinflammation in the acutely injured brain. CONCLUSIONS TBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in hematopoiesis, innate immunity, and neurological function, as well as altered sensitivity to subsequent brain injury.
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Affiliation(s)
- Rodney M Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
| | - Yun Li
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Yun Jiao
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Sarah J Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Niaz Khan
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Kavitha Brunner
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Gregory L Szeto
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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Tenovuo O, Loane DJ. Neuroinflammation is a player in coma, but in which role? Brain 2024; 147:1121-1123. [PMID: 38574286 DOI: 10.1093/brain/awae082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 03/08/2024] [Indexed: 04/06/2024] Open
Abstract
This scientific commentary refers to ‘Neuroimmune activation is associated with neurological outcome in anoxic and traumatic coma’ by Sarton et al. (https://doi.org/10.1093/brain/awae045).
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Affiliation(s)
- Olli Tenovuo
- Department of Clinical Neurosciences, University of Turku, 20520 Turku, Finland
| | - David J Loane
- School of Biochemistry and Immunology, Trinity College Dublin, D02R590 Dublin, Ireland
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3
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Gandasasmita N, Li J, Loane DJ, Semple BD. Experimental Models of Hospital-Acquired Infections After Traumatic Brain Injury: Challenges and Opportunities. J Neurotrauma 2024; 41:752-770. [PMID: 37885226 DOI: 10.1089/neu.2023.0453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023] Open
Abstract
Patients hospitalized after a moderate or severe traumatic brain injury (TBI) are at increased risk of nosocomial infections, including bacterial pneumonia and other upper respiratory tract infections. Infections represent a secondary immune challenge for vulnerable TBI patients that can lead to increased morbidity and poorer long-term prognosis. This review first describes the clinical significance of infections after TBI, delving into the known mechanisms by which a TBI can alter systemic immunological responses towards an immunosuppressive state, leading to promotion of increased vulnerability to infections. Pulmonary dysfunction resulting from respiratory tract infections is considered in the context of neurotrauma, including the bidirectional relationship between the brain and lungs. Turning to pre-clinical modeling, current laboratory approaches to study experimental TBI and lung infections are reviewed, to highlight findings from the limited key studies to date that have incorporated both insults. Then, practical decisions for the experimental design of animal studies of post-injury infections are discussed. Variables associated with the host animal, the infectious agent (e.g., species, strain, dose, and administration route), as well as the timing of the infection relative to the injury model are important considerations for model development. Together, the purpose of this review is to highlight the significant clinical need for increased pre-clinical research into the two-hit insult of a hospital-acquired infection after TBI to encourage further scientific enquiry in the field.
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Affiliation(s)
| | - Jian Li
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - David J Loane
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bridgette D Semple
- Department of Neuroscience, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
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Ritzel RM, Li Y, Jiao Y, Doran SJ, Khan N, Henry RJ, Brunner K, Loane DJ, Faden AI, Szeto GL, Wu J. The brain-bone marrow axis and its implications for chronic traumatic brain injury. Res Sq 2023:rs.3.rs-3356007. [PMID: 37790560 PMCID: PMC10543403 DOI: 10.21203/rs.3.rs-3356007/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function which contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined. To further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham congenic donor mice into otherwise healthy, age-matched, irradiated hosts. After 8 weeks of reconstitution, peripheral myeloid cells from TBI→WT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBI→WT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI showed that longer reconstitution periods were associated with increased microgliosis and leukocyte infiltration. Thus, TBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in innate immunity and neurological function, as well as altered sensitivity to subsequent brain injury.
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Affiliation(s)
- Rodney M. Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, USA
| | - Yun Li
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yun Jiao
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Maryland, USA
| | - Sarah J. Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Niaz Khan
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Rebecca J. Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kavitha Brunner
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - David J. Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Alan I. Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Gregory L. Szeto
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Maryland, USA
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Strogulski NR, Portela LV, Polster BM, Loane DJ. Fundamental Neurochemistry Review: Microglial immunometabolism in traumatic brain injury. J Neurochem 2023; 167:129-153. [PMID: 37759406 PMCID: PMC10655864 DOI: 10.1111/jnc.15959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023]
Abstract
Traumatic brain injury (TBI) is a devastating neurological disorder caused by a physical impact to the brain that promotes diffuse damage and chronic neurodegeneration. Key mechanisms believed to support secondary brain injury include mitochondrial dysfunction and chronic neuroinflammation. Microglia and brain-infiltrating macrophages are responsible for neuroinflammatory cytokine and reactive oxygen species (ROS) production after TBI. Their production is associated with loss of homeostatic microglial functions such as immunosurveillance, phagocytosis, and immune resolution. Beyond providing energy support, mitochondrial metabolic pathways reprogram the pro- and anti-inflammatory machinery in immune cells, providing a critical immunometabolic axis capable of regulating immunologic response to noxious stimuli. In the brain, the capacity to adapt to different environmental stimuli derives, in part, from microglia's ability to recognize and respond to changes in extracellular and intracellular metabolite levels. This capacity is met by an equally plastic metabolism, capable of altering immune function. Microglial pro-inflammatory activation is associated with decreased mitochondrial respiration, whereas anti-inflammatory microglial polarization is supported by increased oxidative metabolism. These metabolic adaptations contribute to neuroimmune responses, placing mitochondria as a central regulator of post-traumatic neuroinflammation. Although it is established that profound neurometabolic changes occur following TBI, key questions related to metabolic shifts in microglia remain unresolved. These include (a) the nature of microglial mitochondrial dysfunction after TBI, (b) the hierarchical positions of different metabolic pathways such as glycolysis, pentose phosphate pathway, glutaminolysis, and lipid oxidation during secondary injury and recovery, and (c) how immunometabolism alters microglial phenotypes, culminating in chronic non-resolving neuroinflammation. In this basic neurochemistry review article, we describe the contributions of immunometabolism to TBI, detail primary evidence of mitochondrial dysfunction and metabolic impairments in microglia and macrophages, discuss how major metabolic pathways contribute to post-traumatic neuroinflammation, and set out future directions toward advancing immunometabolic phenotyping in TBI.
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Affiliation(s)
- Nathan R. Strogulski
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Luis V. Portela
- Neurotrauma and Biomarkers Laboratory, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Brian M. Polster
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - David J. Loane
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
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6
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Makarava N, Mychko O, Molesworth K, Chang JCY, Henry RJ, Tsymbalyuk N, Gerzanich V, Simard JM, Loane DJ, Baskakov IV. Region-Specific Homeostatic Identity of Astrocytes Is Essential for Defining Their Response to Pathological Insults. Cells 2023; 12:2172. [PMID: 37681904 PMCID: PMC10486627 DOI: 10.3390/cells12172172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 08/08/2023] [Accepted: 08/28/2023] [Indexed: 09/09/2023] Open
Abstract
The transformation of astrocytes into reactive states constitutes a biological response of the central nervous system under a variety of pathological insults. Astrocytes display diverse homeostatic identities that are developmentally predetermined and regionally specified. Upon transformation into reactive states associated with neurodegenerative diseases and other neurological disorders, astrocytes acquire diverse reactive phenotypes. However, it is not clear whether their reactive phenotypes are dictated by region-specific homeostatic identity or by the nature of an insult. To address this question, region-specific gene expression profiling was performed for four brain regions (cortex, hippocampus, thalamus, and hypothalamus) in mice using a custom NanoString panel consisting of selected sets of genes associated with astrocyte functions and their reactivity for five conditions: prion disease, traumatic brain injury, brain ischemia, 5XFAD Alzheimer's disease model and normal aging. Upon transformation into reactive states, genes that are predominantly associated with astrocytes were found to respond to insults in a region-specific manner. Regardless of the nature of the insult or the insult-specificity of astrocyte response, strong correlations between undirected GSA (gene set analysis) scores reporting on astrocyte reactivity and on their homeostatic functions were observed within each individual brain region. The insult-specific gene expression signatures did not separate well from each other and instead partially overlapped, forming continuums. The current study demonstrates that region-specific homeostatic identities of astrocytes are important for defining their response to pathological insults. Within region-specific populations, reactive astrocytes show continuums of gene expression signatures, partially overlapping between individual insults.
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Affiliation(s)
- Natallia Makarava
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (N.M.); (J.C.-Y.C.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Olga Mychko
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (N.M.); (J.C.-Y.C.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kara Molesworth
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (N.M.); (J.C.-Y.C.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jennifer Chen-Yu Chang
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (N.M.); (J.C.-Y.C.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Rebecca J. Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA (D.J.L.)
| | - Natalya Tsymbalyuk
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Volodymyr Gerzanich
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - J. Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - David J. Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA (D.J.L.)
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, D02 R590 Dublin, Ireland
| | - Ilia V. Baskakov
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (N.M.); (J.C.-Y.C.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Ritzel RM, Li Y, Jiao Y, Lei Z, Doran SJ, He J, Shahror RA, Henry RJ, Khan R, Tan C, Liu S, Stoica BA, Faden AI, Szeto G, Loane DJ, Wu J. Brain injury accelerates the onset of a reversible age-related microglial phenotype associated with inflammatory neurodegeneration. Sci Adv 2023; 9:eadd1101. [PMID: 36888713 PMCID: PMC9995070 DOI: 10.1126/sciadv.add1101] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
Lipofuscin is an autofluorescent (AF) pigment formed by lipids and misfolded proteins, which accumulates in postmitotic cells with advanced age. Here, we immunophenotyped microglia in the brain of old C57BL/6 mice (>18 months old) and demonstrate that in comparison to young mice, one-third of old microglia are AF, characterized by profound changes in lipid and iron content, phagocytic activity, and oxidative stress. Pharmacological depletion of microglia in old mice eliminated the AF microglia following repopulation and reversed microglial dysfunction. Age-related neurological deficits and neurodegeneration after traumatic brain injury (TBI) were attenuated in old mice lacking AF microglia. Furthermore, increased phagocytic activity, lysosomal burden, and lipid accumulation in microglia persisted for up to 1 year after TBI, were modified by APOE4 genotype, and chronically driven by phagocyte-mediated oxidative stress. Thus, AF may reflect a pathological state in aging microglia associated with increased phagocytosis of neurons and myelin and inflammatory neurodegeneration that can be further accelerated by TBI.
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Affiliation(s)
- Rodney M. Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yun Li
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yun Jiao
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore, MD 21250, USA
| | - Zhuofan Lei
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sarah J. Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Junyun He
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Rami A. Shahror
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Rebecca J. Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Romeesa Khan
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77370, USA
| | - Chunfeng Tan
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77370, USA
| | - Shaolin Liu
- Department of Anatomy, Howard University, Washington, DC 20059, USA
| | - Bogdan A. Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alan I. Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- University of Maryland Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD 21201, USA
| | - Gregory Szeto
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore, MD 21250, USA
- Allen Institute for Immunology and Department of Pediatrics, University of Washington, Seattle, WA 98109, USA
| | - David J. Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- University of Maryland Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD 21201, USA
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Grovola MR, von Reyn C, Loane DJ, Cullen DK. Understanding microglial responses in large animal models of traumatic brain injury: an underutilized resource for preclinical and translational research. J Neuroinflammation 2023; 20:67. [PMID: 36894951 PMCID: PMC9999644 DOI: 10.1186/s12974-023-02730-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/13/2023] [Indexed: 03/11/2023] Open
Abstract
Traumatic brain injury (TBI) often results in prolonged or permanent brain dysfunction with over 2.8 million affected annually in the U.S., including over 56,000 deaths, with over 5 million total survivors exhibiting chronic deficits. Mild TBI (also known as concussion) accounts for over 75% of all TBIs every year. Mild TBI is a heterogeneous disorder, and long-term outcomes are dependent on the type and severity of the initial physical event and compounded by secondary pathophysiological consequences, such as reactive astrocytosis, edema, hypoxia, excitotoxicity, and neuroinflammation. Neuroinflammation has gained increasing attention for its role in secondary injury as inflammatory pathways can have both detrimental and beneficial roles. For example, microglia-resident immune cells of the central nervous system (CNS)-influence cell death pathways and may contribute to progressive neurodegeneration but also aid in debris clearance and neuroplasticity. In this review, we will discuss the acute and chronic role of microglia after mild TBI, including critical protective responses, deleterious effects, and how these processes vary over time. These descriptions are contextualized based on interspecies variation, sex differences, and prospects for therapy. We also highlight recent work from our lab that was the first to describe microglial responses out to chronic timepoints after diffuse mild TBI in a clinically relevant large animal model. The scaled head rotational acceleration of our large animal model, paired with the gyrencephalic architecture and appropriate white:gray matter ratio, allows us to produce pathology with the same anatomical patterns and distribution of human TBI, and serves as an exemplary model to examine complex neuroimmune response post-TBI. An improved understanding of microglial influences in TBI could aid in the development of targeted therapeutics to accentuate positive effects while attenuating detrimental post-injury responses over time.
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Affiliation(s)
- Michael R Grovola
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA.,Department of Neurosurgery, Center for Brain Injury & Repair, University of Pennsylvania, 105E Hayden Hall/3320 Smith Walk, Philadelphia, PA, 19104, USA
| | - Catherine von Reyn
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - David J Loane
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland.,Department of Anesthesiology and Shock, Trauma, and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - D Kacy Cullen
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. .,Department of Neurosurgery, Center for Brain Injury & Repair, University of Pennsylvania, 105E Hayden Hall/3320 Smith Walk, Philadelphia, PA, 19104, USA. .,Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA.
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Hegdekar N, Sarkar C, Bustos S, Ritzel RM, Hanscom M, Ravishankar P, Philkana D, Wu J, Loane DJ, Lipinski MM. Inhibition of autophagy in microglia and macrophages exacerbates innate immune responses and worsens brain injury outcomes. Autophagy 2023:1-19. [PMID: 36652438 DOI: 10.1080/15548627.2023.2167689] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Excessive and prolonged neuroinflammation following traumatic brain injury (TBI) contributes to long-term tissue damage and poor functional outcomes. However, the mechanisms contributing to exacerbated inflammatory responses after brain injury remain poorly understood. Our previous work showed that macroautophagy/autophagy flux is inhibited in neurons following TBI in mice and contributes to neuronal cell death. In the present study, we demonstrate that autophagy is also inhibited in activated microglia and infiltrating macrophages, and that this potentiates injury-induced neuroinflammatory responses. Macrophage/microglia-specific knockout of the essential autophagy gene Becn1 led to overall increase in neuroinflammation after TBI. In particular, we observed excessive activation of the innate immune responses, including both the type-I interferon and inflammasome pathways. Defects in microglial and macrophage autophagy following injury were associated with decreased phagocytic clearance of danger/damage-associated molecular patterns (DAMP) responsible for activation of the cellular innate immune responses. Our data also demonstrated a role for precision autophagy in targeting and degradation of innate immune pathways components, such as the NLRP3 inflammasome. Finally, inhibition of microglial/macrophage autophagy led to increased neurodegeneration and worse long-term cognitive outcomes after TBI. Conversely, increasing autophagy by treatment with rapamycin decreased inflammation and improved outcomes in wild-type mice after TBI. Overall, our work demonstrates that inhibition of autophagy in microglia and infiltrating macrophages contributes to excessive neuroinflammation following brain injury and in the long term may prevent resolution of inflammation and tissue regeneration.Abbreviations: Becn1/BECN1, beclin 1, autophagy related; CCI, controlled cortical impact; Cybb/CYBB/NOX2: cytochrome b-245, beta polypeptide; DAMP, danger/damage-associated molecular patterns; Il1b/IL1B/Il-1β, interleukin 1 beta; LAP, LC3-associated phagocytosis; Map1lc3b/MAP1LC3/LC3, microtubule-associated protein 1 light chain 3 beta; Mefv/MEFV/TRIM20: Mediterranean fever; Nos2/NOS2/iNOS: nitric oxide synthase 2, inducible; Nlrp3/NLRP3, NLR family, pyrin domain containing 3; Sqstm1/SQSTM1/p62, sequestosome 1; TBI, traumatic brain injury; Tnf/TNF/TNF-α, tumor necrosis factor; Ulk1/ULK1, unc-51 like kinase 1.
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Affiliation(s)
- Nivedita Hegdekar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Chinmoy Sarkar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sabrina Bustos
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Rodney M Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Neurology, McGovern Medical School, University of Texas, Houston, Tx, USA
| | - Marie Hanscom
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Prarthana Ravishankar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Deepika Philkana
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA.,School of Biochemistry and Immunology, Trinity College, Dublin, Ireland
| | - Marta M Lipinski
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
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10
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Pischiutta F, Caruso E, Cavaleiro H, Salgado AJ, Loane DJ, Zanier ER. Mesenchymal stromal cell secretome for traumatic brain injury: Focus on immunomodulatory action. Exp Neurol 2022; 357:114199. [PMID: 35952763 DOI: 10.1016/j.expneurol.2022.114199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/14/2022] [Accepted: 08/03/2022] [Indexed: 11/15/2022]
Abstract
The severity and long-term consequences of brain damage in traumatic brain injured (TBI) patients urgently calls for better neuroprotective/neuroreparative strategies for this devastating disorder. Mesenchymal stromal cells (MSCs) hold great promise and have been shown to confer neuroprotection in experimental TBI, mainly through paracrine mechanisms via secreted bioactive factors (i.e. secretome), which indicates significant potential for a cell-free neuroprotective approach. The secretome is composed of cytokines, chemokines, growth factors, proteins, lipids, nucleic acids, metabolites, and extracellular vesicles; it may offer advantages over MSCs in terms of delivery, safety, and variability of therapeutic response for brain injury. Immunomodulation by molecular factors secreted by MSCs is considered to be a key mechanism involved in their multi-potential therapeutic effects. Regulated neuroinflammation is required for healthy remodeling of central nervous system during development and adulthood. Moreover, immune cells and their secreted factors can also contribute to tissue repair and neurological recovery following acute brain injury. However, a chronic and maladaptive neuroinflammatory response can exacerbate TBI and contribute to progressive neurodegeneration and long-term neurological impairments. Here, we review the evidence for MSC-derived secretome as a therapy for TBI. Our framework incorporates a detailed analysis of in vitro and in vivo studies investigating the effects of the secretome on clinically relevant neurological and histopathological outcomes. We also describe the activation of immune cells after TBI and the immunomodulatory properties exerted by mediators released in the secretome. We then describe how ageing modifies central and systemic immune responses to TBI and discuss challenges and opportunities of developing secretome based neuroprotective therapies for elderly TBI populations. Finally, strategies aimed at modulating the secretome in order to boost its efficacy for TBI will also be discussed.
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Affiliation(s)
- Francesca Pischiutta
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Department of Neuroscience, Milan, Italy
| | - Enrico Caruso
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Department of Neuroscience, Milan, Italy; Neuroscience Intensive Care Unit, Department of Anesthesia and Critical Care, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Helena Cavaleiro
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Department of Neuroscience, Milan, Italy; Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus de Gualtar, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal; Stemmatters, Biotechnology and Regenerative Medicine, Guimarães, Portugal
| | - Antonio J Salgado
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus de Gualtar, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal
| | - David J Loane
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Elisa R Zanier
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Department of Neuroscience, Milan, Italy.
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11
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Barrett JP, Knoblach SM, Bhattacharya S, Gordish-Dressman H, Stoica BA, Loane DJ. Traumatic Brain Injury Induces cGAS Activation and Type I Interferon Signaling in Aged Mice. Front Immunol 2021; 12:710608. [PMID: 34504493 PMCID: PMC8423402 DOI: 10.3389/fimmu.2021.710608] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 08/05/2021] [Indexed: 12/21/2022] Open
Abstract
Aging adversely affects inflammatory processes in the brain, which has important implications in the progression of neurodegenerative disease. Following traumatic brain injury (TBI), aged animals exhibit worsened neurological function and exacerbated microglial-associated neuroinflammation. Type I Interferons (IFN-I) contribute to the development of TBI neuropathology. Further, the Cyclic GMP-AMP Synthase (cGAS) and Stimulator of Interferon Genes (STING) pathway, a key inducer of IFN-I responses, has been implicated in neuroinflammatory activity in several age-related neurodegenerative diseases. Here, we set out to investigate the effects of TBI on cGAS/STING activation, IFN-I signaling and neuroinflammation in young and aged C57Bl/6 male mice. Using a controlled cortical impact model, we evaluated transcriptomic changes in the injured cortex at 24 hours post-injury, and confirmed activation of key neuroinflammatory pathways in biochemical studies. TBI induced changes were highly enriched for transcripts that were involved in inflammatory responses to stress and host defense. Deeper analysis revealed that TBI increased expression of IFN-I related genes (e.g. Ifnb1, Irf7, Ifi204, Isg15) and IFN-I signaling in the injured cortex of aged compared to young mice. There was also a significant age-related increase in the activation of the DNA-recognition pathway, cGAS, which is a key mechanism to propagate IFN-I responses. Finally, enhanced IFN-I signaling in the aged TBI brain was confirmed by increased phosphorylation of STAT1, an important IFN-I effector molecule. This age-related activation of cGAS and IFN-I signaling may prove to be a mechanistic link between microglial-associated neuroinflammation and neurodegeneration in the aged TBI brain.
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Affiliation(s)
- James P Barrett
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Susan M Knoblach
- Center for Genetic Medicine Research, Children's Research Institute, Children's National Health System, Washington, DC, United States.,Department of Genomics and Precision Medicine, George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Surajit Bhattacharya
- Center for Genetic Medicine Research, Children's Research Institute, Children's National Health System, Washington, DC, United States
| | - Heather Gordish-Dressman
- Center for Translational Science, Children's Research Institute, Children's National Health System, Washington, DC, United States.,Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, United States.,Veterans Affairs (VA) Maryland Health Care System, Baltimore VA Medical Center, Baltimore, MD, United States
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, United States.,School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
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12
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Abstract
Traumatic brain injury (TBI) is a chronic and progressive disease, and management requires an understanding of both the primary neurological injury and the secondary sequelae that affect peripheral organs, including the gastrointestinal (GI) tract. The brain-gut axis is composed of bidirectional pathways through which TBI-induced neuroinflammation and neurodegeneration impact gut function. The resulting TBI-induced dysautonomia and systemic inflammation contribute to the secondary GI events, including dysmotility and increased mucosal permeability. These effects shape, and are shaped by, changes in microbiota composition and activation of resident and recruited immune cells. Microbial products and immune cell mediators in turn modulate brain-gut activity. Importantly, secondary enteric inflammatory challenges prolong systemic inflammation and worsen TBI-induced neuropathology and neurobehavioral deficits. The importance of brain-gut communication in maintaining GI homeostasis highlights it as a viable therapeutic target for TBI. Currently, treatments directed toward dysautonomia, dysbiosis, and/or systemic inflammation offer the most promise.
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Affiliation(s)
- Marie Hanscom
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - David J. Loane
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Terez Shea-Donohue
- Division of Digestive Diseases and Nutrition, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland, USA
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13
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LaPlaca MC, Huie JR, Alam HB, Bachstetter AD, Bayir H, Bellgowan PF, Cummings D, Dixon CE, Ferguson AR, Ferland-Beckham C, Floyd CL, Friess SH, Galanopoulou AS, Hall ED, Harris NG, Hawkins BE, Hicks RR, Hulbert LE, Johnson VE, Kabitzke PA, Lafrenaye AD, Lemmon VP, Lifshitz CW, Lifshitz J, Loane DJ, Misquitta L, Nikolian VC, Noble-Haeusslein LJ, Smith DH, Taylor-Burds C, Umoh N, Vovk O, Williams AM, Young M, Zai LJ. Pre-Clinical Common Data Elements for Traumatic Brain Injury Research: Progress and Use Cases. J Neurotrauma 2021; 38:1399-1410. [PMID: 33297844 PMCID: PMC8082734 DOI: 10.1089/neu.2020.7328] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Traumatic brain injury (TBI) is an extremely complex condition due to heterogeneity in injury mechanism, underlying conditions, and secondary injury. Pre-clinical and clinical researchers face challenges with reproducibility that negatively impact translation and therapeutic development for improved TBI patient outcomes. To address this challenge, TBI Pre-clinical Working Groups expanded upon previous efforts and developed common data elements (CDEs) to describe the most frequently used experimental parameters. The working groups created 913 CDEs to describe study metadata, animal characteristics, animal history, injury models, and behavioral tests. Use cases applied a set of commonly used CDEs to address and evaluate the degree of missing data resulting from combining legacy data from different laboratories for two different outcome measures (Morris water maze [MWM]; RotorRod/Rotarod). Data were cleaned and harmonized to Form Structures containing the relevant CDEs and subjected to missing value analysis. For the MWM dataset (358 animals from five studies, 44 CDEs), 50% of the CDEs contained at least one missing value, while for the Rotarod dataset (97 animals from three studies, 48 CDEs), over 60% of CDEs contained at least one missing value. Overall, 35% of values were missing across the MWM dataset, and 33% of values were missing for the Rotarod dataset, demonstrating both the feasibility and the challenge of combining legacy datasets using CDEs. The CDEs and the associated forms created here are available to the broader pre-clinical research community to promote consistent and comprehensive data acquisition, as well as to facilitate data sharing and formation of data repositories. In addition to addressing the challenge of standardization in TBI pre-clinical studies, this effort is intended to bring attention to the discrepancies in assessment and outcome metrics among pre-clinical laboratories and ultimately accelerate translation to clinical research.
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Affiliation(s)
- Michelle C. LaPlaca
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, USA
- San Francisco Veterans Affairs Health Care System, San Francisco, California, USA
| | - J. Russell Huie
- Brain and Spinal Injury Center, Department of Neurological Surgery, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA
| | - Hasan B. Alam
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Adam D. Bachstetter
- Department of Neuroscience, University of Kentucky, Lexington, Kentucky, USA
| | - Hűlya Bayir
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | | | - C. Edward Dixon
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Adam R. Ferguson
- Brain and Spinal Injury Center, Department of Neurological Surgery, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA
| | | | - Candace L. Floyd
- Department of Physical Medicine and Rehabilitation, University of Utah, Salt Lake City, Utah, USA
| | - Stuart H. Friess
- Division of Critical Care Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | | | - Edward D. Hall
- Department of Neuroscience, University of Kentucky, Lexington, Kentucky, USA
| | - Neil G. Harris
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, California, USA
| | - Bridget E. Hawkins
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Lindsey E. Hulbert
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas, USA
| | - Victoria E. Johnson
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Audrey D. Lafrenaye
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Vance P. Lemmon
- Department of Neurological Surgery, University of Miami, Miami, Florida, USA
| | - Carrie W. Lifshitz
- Department of Child Health, University of Arizona College of Medicine Phoenix, Phoenix, Arizona, USA
| | - Jonathan Lifshitz
- Department of Child Health, University of Arizona College of Medicine Phoenix, Phoenix, Arizona, USA
| | - David J. Loane
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | | | | | | | - Douglas H. Smith
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Nsini Umoh
- Department of Defense, U.S. Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, USA
| | - Olga Vovk
- National Institutes of Health, Bethesda, Maryland, USA
| | - Aaron M. Williams
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Margaret Young
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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14
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Hanscom M, Loane DJ, Aubretch T, Leser J, Molesworth K, Hedgekar N, Ritzel RM, Abulwerdi G, Shea-Donohue T, Faden AI. Acute colitis during chronic experimental traumatic brain injury in mice induces dysautonomia and persistent extraintestinal, systemic, and CNS inflammation with exacerbated neurological deficits. J Neuroinflammation 2021; 18:24. [PMID: 33461596 PMCID: PMC7814749 DOI: 10.1186/s12974-020-02067-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 12/21/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Disruptions of brain-gut axis have been implicated in the progression of a variety of gastrointestinal (GI) disorders and central nervous system (CNS) diseases and injuries, including traumatic brain injury (TBI). TBI is a chronic disease process characterized by persistent secondary injury processes which can be exacerbated by subsequent challenges. Enteric pathogen infection during chronic TBI worsened cortical lesion volume; however, the pathophysiological mechanisms underlying the damaging effects of enteric challenge during chronic TBI remain unknown. This preclinical study examined the effect of intestinal inflammation during chronic TBI on associated neurobehavioral and neuropathological outcomes, systemic inflammation, and dysautonomia. METHODS Dextran sodium sulfate (DSS) was administered to adult male C57BL/6NCrl mice 28 days following craniotomy (Sham) or TBI for 7 days to induce intestinal inflammation, followed by a return to normal drinking water for an additional 7 to 28 days for recovery; uninjured animals (Naïve) served as an additional control group. Behavioral testing was carried out prior to, during, and following DSS administration to assess changes in motor and cognitive function, social behavior, and mood. Electrocardiography was performed to examine autonomic balance. Brains were collected for histological and molecular analyses of injury lesion, neurodegeneration, and neuroinflammation. Blood, colons, spleens, mesenteric lymph nodes (mLNs), and thymus were collected for morphometric analyses and/or immune characterization by flow cytometry. RESULTS Intestinal inflammation 28 days after craniotomy or TBI persistently induced, or exacerbated, respectively, deficits in fine motor coordination, cognition, social behavior, and anxiety-like behavior. Behavioral changes were associated with an induction, or exacerbation, of hippocampal neuronal cell loss and microglial activation in Sham and TBI mice administered DSS, respectively. Acute DSS administration resulted in a sustained systemic immune response with increases in myeloid cells in blood and spleen, as well as myeloid cells and lymphocytes in mesenteric lymph nodes. Dysautonomia was also induced in Sham and TBI mice administered DSS, with increased sympathetic tone beginning during DSS administration and persisting through the first recovery week. CONCLUSION Intestinal inflammation during chronic experimental TBI causes a sustained systemic immune response and altered autonomic balance that are associated with microglial activation, increased neurodegeneration, and persistent neurological deficits.
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Affiliation(s)
- Marie Hanscom
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA.
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
| | - Taryn Aubretch
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
| | - Jenna Leser
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
| | - Kara Molesworth
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
| | - Nivedita Hedgekar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
| | - Rodney M Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
| | - Gelareh Abulwerdi
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
| | - Terez Shea-Donohue
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF #6-016, Baltimore, MD, 21201, USA
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15
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Henry RJ, Loane DJ. Targeting chronic and evolving neuroinflammation following traumatic brain injury to improve long-term outcomes: insights from microglial-depletion models. Neural Regen Res 2021; 16:976-977. [PMID: 33229740 PMCID: PMC8178770 DOI: 10.4103/1673-5374.297068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA; School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
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16
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Li Y, Ritzel RM, Khan N, Cao T, He J, Lei Z, Matyas JJ, Sabirzhanov B, Liu S, Li H, Stoica BA, Loane DJ, Faden AI, Wu J. Delayed microglial depletion after spinal cord injury reduces chronic inflammation and neurodegeneration in the brain and improves neurological recovery in male mice. Am J Cancer Res 2020; 10:11376-11403. [PMID: 33052221 PMCID: PMC7545988 DOI: 10.7150/thno.49199] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 09/02/2020] [Indexed: 12/15/2022] Open
Abstract
Neuropsychological deficits, including impairments in learning and memory, occur after spinal cord injury (SCI). In experimental SCI models, we and others have reported that such changes reflect sustained microglia activation in the brain that is associated with progressive neurodegeneration. In the present study, we examined the effect of pharmacological depletion of microglia on posttraumatic cognition, depressive-like behavior, and brain pathology after SCI in mice. Methods: Young adult male C57BL/6 mice were subjected to moderate/severe thoracic spinal cord contusion. Microglial depletion was induced with the colony-stimulating factor 1 receptor (CSF1R) antagonist PLX5622 administered starting either 3 weeks before injury or one day post-injury and continuing through 6 weeks after SCI. Neuroinflammation in the injured spinal cord and brain was assessed using flow cytometry and NanoString technology. Neurological function was evaluated using a battery of neurobehavioral tests including motor function, cognition, and depression. Lesion volume and neuronal counts were quantified by unbiased stereology. Results: Flow cytometry analysis demonstrated that PLX5622 pre-treatment significantly reduced the number of microglia, as well as infiltrating monocytes and neutrophils, and decreased reactive oxygen species production in these cells from injured spinal cord at 2-days post-injury. Post-injury PLX5622 treatment reduced both CD45int microglia and CD45hi myeloid counts at 7-days. Following six weeks of PLX5622 treatment, there were substantial changes in the spinal cord and brain transcriptomes, including those involved in neuroinflammation. These alterations were associated with improved neuronal survival in the brain and neurological recovery. Conclusion: These findings indicate that pharmacological microglia-deletion reduces neuroinflammation in the injured spinal cord and brain, improving recovery of cognition, depressive-like behavior, and motor function.
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17
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Henry RJ, Meadows VE, Stoica BA, Faden AI, Loane DJ. Longitudinal Assessment of Sensorimotor Function after Controlled Cortical Impact in Mice: Comparison of Beamwalk, Rotarod, and Automated Gait Analysis Tests. J Neurotrauma 2020; 37:2709-2717. [PMID: 32484024 DOI: 10.1089/neu.2020.7139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Traumatic brain injury (TBI) patients are reported to experience long-term sensorimotor dysfunction, with gait deficits evident up to 2 years after the initial brain trauma. Experimental TBI including rodent models of penetrating ballistic-like brain injury and severe controlled cortical impact (CCI) can induce impairments in static and dynamic gait parameters. It is reported that the majority of deficits in gait-related parameters occur during the acute phase post-injury, as functional outcomes return toward baseline levels at chronic time points. In the present study, we carried out a longitudinal analysis of static, temporal and dynamic gait patterns following moderate-level CCI in adult male C57Bl/6J mice using the automated gait analysis apparatus, CatWalk. For comparison, we also performed longitudinal assessment of fine-motor coordination and function in CCI mice using more traditional sensorimotor behavioral tasks such as the beamwalk and accelerating rotarod tasks. We determined that longitudinal CatWalk analysis did not detect TBI-induced deficits in static, temporal, or dynamic gait parameters at acute or chronic time points. In contrast, the rotarod and beamwalk tasks showed that CCI mice had significant motor function impairments as demonstrated by deficits in balance and fine-motor coordination through 28 days post-injury. Stereological analysis confirmed that CCI produced a significant lesion in the parietal cortex at 28 days post-injury. Overall, these findings demonstrate that CatWalk analysis of gait parameters is not useful for assessment of long-term sensorimotor dysfunction after CCI, and that more traditional neurobehavioral tests should be used to quantify acute and chronic deficits in sensorimotor function.
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Affiliation(s)
- Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Victoria E Meadows
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA.,School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
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18
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Abulwerdi G, Stoica BA, Loane DJ, Faden AI. Putative mGluR4 positive allosteric modulators activate G i-independent anti-inflammatory mechanisms in microglia. Neurochem Int 2020; 138:104770. [PMID: 32454165 DOI: 10.1016/j.neuint.2020.104770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/11/2020] [Accepted: 05/15/2020] [Indexed: 01/23/2023]
Abstract
Chronic dysregulated microglial activation may lead to persistent inflammation and progressive neurodegeneration. A previous study reported that ADX88178, a putative metabotropic glutamate receptor 4 (mGluR4) positive allosteric modulator (PAM), exerts anti-inflammatory effects in microglia by activating mGluR4. We employed in vitro models of immortalized microglia cell lines and primary microglia to elucidate the molecular mechanisms responsible for the regulation of inflammatory pathways by ADX88178 and other mGluR4 PAMs. ADX88178 downregulated lipopolysaccharide (LPS)-induced expression of pro-inflammatory mediators, including TNF-α, IL-1β, CCL-2, IL-6, NOS2, and miR-155, as well as NO levels, in BV2 cells and primary microglia. Other mGluR4 modulators had divergent activities; VU0361737 (PAM) showed anti-inflammatory effects, whereas the orthosteric group III agonist, L-AP4, and VU0155041 (PAM) displayed no anti-inflammatory actions. In contrast to the earlier report, ADX88178 anti-inflammatory effects appeared to be mGluR4-independent as mGluR4 expression in our in vitro models was very low and its actions were not altered by pharmacological or molecular inhibition of mGluR4. Moreover, we showed that ADX88178 activated Gi-independent, alternative signaling pathways as indicated by the absence of pertussis toxin-mediated inhibition and by increased phosphorylation of cAMP-response element binding protein (CREB), an inhibitor of the NFkB pro-inflammatory pathway. ADX88178 also attenuated NFkB activation by reducing the degradation of IkB and the associated translocation of NFkB-p65 to the nucleus. ADX88178 did not exert its anti-inflammatory effects through adenosine receptors, reported as mGluR4 heteromerization partners. Thus, our results indicate that in microglia, putative mGluR4 PAMs activate mGluR4/Gi-independent mechanisms to attenuate pro-inflammatory pathways.
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Affiliation(s)
- Gelareh Abulwerdi
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
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19
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Doran SJ, Henry RJ, Shirey KA, Barrett JP, Ritzel RM, Lai W, Blanco JC, Faden AI, Vogel SN, Loane DJ. Early or Late Bacterial Lung Infection Increases Mortality After Traumatic Brain Injury in Male Mice and Chronically Impairs Monocyte Innate Immune Function. Crit Care Med 2020; 48:e418-e428. [PMID: 32149839 PMCID: PMC7541908 DOI: 10.1097/ccm.0000000000004273] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVES Respiratory infections in the postacute phase of traumatic brain injury impede optimal recovery and contribute substantially to overall morbidity and mortality. This study investigated bidirectional innate immune responses between the injured brain and lung, using a controlled cortical impact model followed by secondary Streptococcus pneumoniae infection in mice. DESIGN Experimental study. SETTING Research laboratory. SUBJECTS Adult male C57BL/6J mice. INTERVENTIONS C57BL/6J mice were subjected to sham surgery or moderate-level controlled cortical impact and infected intranasally with S. pneumoniae (1,500 colony-forming units) or vehicle (phosphate-buffered saline) at 3 or 60 days post-injury. MAIN RESULTS At 3 days post-injury, S. pneumoniae-infected traumatic brain injury mice (TBI + Sp) had a 25% mortality rate, in contrast to no mortality in S. pneumoniae-infected sham (Sham + Sp) animals. TBI + Sp mice infected 60 days post-injury had a 60% mortality compared with 5% mortality in Sham + Sp mice. In both studies, TBI + Sp mice had poorer motor function recovery compared with TBI + PBS mice. There was increased expression of pro-inflammatory markers in cortex of TBI + Sp compared with TBI + PBS mice after both early and late infection, indicating enhanced post-traumatic neuroinflammation. In addition, monocytes from lungs of TBI + Sp mice were immunosuppressed acutely after traumatic brain injury and could not produce interleukin-1β, tumor necrosis factor-α, or reactive oxygen species. In contrast, after delayed infection monocytes from TBI + Sp mice had higher levels of interleukin-1β, tumor necrosis factor-α, and reactive oxygen species when compared with Sham + Sp mice. Increased bacterial burden and pathology was also found in lungs of TBI + Sp mice. CONCLUSIONS Traumatic brain injury causes monocyte functional impairments that may affect the host's susceptibility to respiratory infections. Chronically injured mice had greater mortality following S. pneumoniae infection, which suggests that respiratory infections even late after traumatic brain injury may pose a more serious threat than is currently appreciated.
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Affiliation(s)
- Sarah J Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD
| | - Kari Ann Shirey
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD
| | - James P Barrett
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD
| | - Rodney M Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD
| | - Wendy Lai
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD
| | | | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD
| | - Stefanie N Vogel
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
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20
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Bhat SA, Henry RJ, Blanchard AC, Stoica BA, Loane DJ, Faden AI. Enhanced Akt/GSK-3β/CREB signaling mediates the anti-inflammatory actions of mGluR5 positive allosteric modulators in microglia and following traumatic brain injury in male mice. J Neurochem 2020; 156:225-248. [PMID: 31926033 DOI: 10.1111/jnc.14954] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/16/2019] [Accepted: 01/02/2020] [Indexed: 12/20/2022]
Abstract
We have previously shown that treatment with a mGluR5 positive allosteric modulator (PAM) is neuroprotective after experimental traumatic brain injury (TBI), limiting post-traumatic neuroinflammation by reducing pro-inflammatory microglial activation and promoting anti-inflammatory and neuroprotective responses. However, the specific molecular mechanisms governing this anti-inflammatory shift in microglia remain unknown. Here we show that the mGluR5 PAM, VU0360172 (VuPAM), regulates microglial inflammatory responses through activation of Akt, resulting in the inhibition of GSK-3β. GSK-3β regulates the phosphorylation of CREB, thereby controlling the expression of inflammation-related genes and microglial plasticity. The anti-inflammatory action of VuPAM in microglia is reversed by inhibiting Akt/GSK-3β/CREB signaling. Using a well-characterized TBI model and CX3CR1gfp/+ mice to visualize microglia in vivo, we demonstrate that VuPAM enhances Akt/GSK-3β/CREB signaling in the injured cortex, as well as anti-inflammatory microglial markers. Furthermore, in situ analysis revealed that GFP + microglia in the cortex of VuPAM-treated TBI mice co-express pCREB and the anti-inflammatory microglial phenotype marker YM1. Taken together, our data show that VuPAM decreases pro-inflammatory microglial activation by modulating Akt/GSK-3β/CREB signaling. These findings serve to clarify the potential neuroprotective mechanisms of mGluR5 PAM treatment after TBI, and suggest novel therapeutic targets for post-traumatic neuroinflammation. Cover Image for this issue: https://doi.org/10.1111/jnc.15048.
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Affiliation(s)
- Shahnawaz A Bhat
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alexa C Blanchard
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.,School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
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21
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Sun M, McDonald SJ, Brady RD, Collins-Praino L, Yamakawa GR, Monif M, O'Brien TJ, Cloud GC, Sobey CG, Mychasiuk R, Loane DJ, Shultz SR. The need to incorporate aged animals into the preclinical modeling of neurological conditions. Neurosci Biobehav Rev 2019; 109:114-128. [PMID: 31877345 DOI: 10.1016/j.neubiorev.2019.12.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 12/04/2019] [Accepted: 12/19/2019] [Indexed: 12/14/2022]
Abstract
Neurological conditions such as traumatic brain injury, stroke, Parkinson's disease, epilepsy, multiple sclerosis, and Alzheimer's disease are serious clinical problems that affect millions of people worldwide. The majority of clinical trials for these common conditions have failed, and there is a critical need to understand why treatments in preclinical animal models do not translate to patients. Many patients with these conditions are middle-aged or older, however, the majority of preclinical studies have used only young-adult animals. Considering that aging involves biological changes that are relevant to the pathobiology of neurological diseases, the lack of aged subjects in preclinical research could contribute to translational failures. This paper details how aging affects biological processes involved in neurological conditions, and reviews aging research in the context of traumatic brain injury, stroke, Parkinson's disease, epilepsy, multiple sclerosis, and Alzheimer's disease. We conclude that aging is an important, but often overlooked, factor that influences biology and outcomes in neurological conditions, and provide suggestions to improve our understanding and treatment of these diseases in aged patients.
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Affiliation(s)
- Mujun Sun
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia
| | - Stuart J McDonald
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Rhys D Brady
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Melbourne, VIC 3052, Australia
| | - Lyndsey Collins-Praino
- Department of Medical Sciences, Adelaide Medical School, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Glenn R Yamakawa
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia
| | - Mastura Monif
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Melbourne, VIC 3052, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia
| | - Geoffrey C Cloud
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia; Department of Stroke Services, Alfred Hospital, Melbourne, VIC 3004, Australia
| | - Christopher G Sobey
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin 2, Ireland
| | - Sandy R Shultz
- Department of Neuroscience, Monash University, Melbourne, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Melbourne, VIC 3052, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia.
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22
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Kumar A, Henry RJ, Stoica BA, Loane DJ, Abulwerdi G, Bhat SA, Faden AI. Neutral Sphingomyelinase Inhibition Alleviates LPS-Induced Microglia Activation and Neuroinflammation after Experimental Traumatic Brain Injury. J Pharmacol Exp Ther 2019; 368:338-352. [PMID: 30563941 PMCID: PMC6367691 DOI: 10.1124/jpet.118.253955] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/14/2018] [Indexed: 12/17/2022] Open
Abstract
Neuroinflammation is one of the key secondary injury mechanisms triggered by traumatic brain injury (TBI). Microglial activation, a hallmark of brain neuroinflammation, plays a critical role in regulating immune responses after TBI and contributes to progressive neurodegeneration and neurologic deficits following brain trauma. Here we evaluated the role of neutral sphingomyelinase (nSMase) in microglial activation by examining the effects of the nSMase inhibitors altenusin and GW4869 in vitro (using BV2 microglia cells and primary microglia), as well as in a controlled cortical injury (CCI) model in adult male C57BL/6 mice. Pretreatment of altenusin or GW4869 prior to lipopolysaccharide (LPS) stimulation for 4 or 24 hours, significantly downregulated gene expression of the pro-inflammatory mediators TNF-α, IL-1β, IL-6, iNOS, and CCL2 in microglia and reduced the release of nitric oxide and TNF-α These nSMase inhibitors also attenuated the release of microparticles and phosphorylation of p38 MAPK and ERK1/2. In addition, altenusin pretreatment also reduced the gene expression of multiple inflammatory markers associated with microglial activation after experimental TBI, including TNF-α, IL-1β, IL-6, iNOS, CCL2, CD68, NOX2, and p22phox Overall, our data demonstrate that nSMase inhibitors attenuate multiple inflammatory pathways associated with microglial activation in vitro and after experimental TBI. Thus, nSMase inhibitors may represent promising therapeutics agents targeting neuroinflammation.
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Affiliation(s)
- Asit Kumar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Gelareh Abulwerdi
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Shahnawaz A Bhat
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
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23
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Stewart W, Allinson K, Al-Sarraj S, Bachmeier C, Barlow K, Belli A, Burns MP, Carson A, Crawford F, Dams-O'Connor K, Diaz-Arrastia R, Dixon CE, Edlow BL, Ferguson S, Fischl B, Folkerth RD, Gentleman S, Giza CC, Grady MS, Helmy A, Herceg M, Holton JL, Howell D, Hutchinson PJ, Iacono D, Iglesias JE, Ikonomovic MD, Johnson VE, Keene CD, Kofler JK, Koliatsos VE, Lee EB, Levin H, Lifshitz J, Ling H, Loane DJ, Love S, Maas AI, Marklund N, Master CL, McElvenny DM, Meaney DF, Menon DK, Montine TJ, Mouzon B, Mufson EJ, Ojo JO, Prins M, Revesz T, Ritchie CW, Smith C, Sylvester R, Tang CY, Trojanowski JQ, Urankar K, Vink R, Wellington C, Wilde EA, Wilson L, Yeates K, Smith DH. Primum non nocere: a call for balance when reporting on CTE. Lancet Neurol 2019; 18:231-233. [PMID: 30784550 PMCID: PMC6594011 DOI: 10.1016/s1474-4422(19)30020-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/21/2019] [Indexed: 12/15/2022]
Affiliation(s)
- William Stewart
- Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK; Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow, UK; Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
| | - Kieren Allinson
- Department of Pathology, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK
| | - Safa Al-Sarraj
- The Institute of Psychiatry Psychology and Neurosciences, King's College London, London, UK
| | - Corbin Bachmeier
- Roskamp Institute, Sarasota, Florida, USA; The Open University, Milton Keynes, UK; Bay Pines VA Healthcare System, Bay Pines, Florida, USA
| | - Karen Barlow
- Child Health Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Antonio Belli
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
| | - Mark P Burns
- Georgetown University Medical Center, Washington DC, DC, USA
| | - Alan Carson
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Fiona Crawford
- Roskamp Institute, Sarasota, Florida, USA; The Open University, Milton Keynes, UK; James A Haley Veterans' Hospital, Tampa, FL, USA
| | - Kristen Dams-O'Connor
- Department of Rehabilitation Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA; Penn Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA, USA
| | - C Edward Dixon
- Department of Neurological Surgery, Brain Trauma Research Center, University of Pittsburgh, Pittsburgh, PA, USA; Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA, USA
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Scott Ferguson
- Roskamp Institute, Sarasota, Florida, USA; Roskamp Institute, Sarasota, Florida, USA; James A Haley Veterans' Hospital, Tampa, FL, USA
| | - Bruce Fischl
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Rebecca D Folkerth
- City of New York Office of the Chief Medical Examiner, and New York University School of Medicine, New York NY, USA
| | - Steve Gentleman
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Christopher C Giza
- UCLA Steve Tisch BrainSPORT Program, Los Angeles, CA, USA; Departments of Pediatrics and Neurosurgery, David Geffen School of Medicine and UCLA Mattel Children's Hospital, University of California, Los Angeles, CA, USA
| | - M Sean Grady
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA
| | - Adel Helmy
- Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK
| | - Mark Herceg
- Department of Physical Medicine and Rehabilitation, Phelps Hospital Northwell Health, New York, NY, USA; School of Public Health, New York Medical College, New York, NY, USA
| | - Janice L Holton
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - David Howell
- Sports Medicine Center, Children's Hospital Colorado, Aurora, CO, USA; Department of Orthopedics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Peter J Hutchinson
- Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK
| | - Diego Iacono
- Neuropathology Research, Biomedical Research Institute of New Jersey, Cedar Knolls, NJ, USA; Atlantic Neuroscience Institute, Atlantic Health System, Morristown, NJ, USA
| | - Juan E Iglesias
- Centre for Medical Image Computing, Department of Medical Physics and Biomedical Engineering, University College London, London, UK; Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Milos D Ikonomovic
- Departments of Neurology and Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Victoria E Johnson
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA; Penn Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA, USA
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Julia K Kofler
- Department of Pathology, Division of Neuropathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Vassilis E Koliatsos
- Departments of Pathology, Neurology, and Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Neuropsychiatry Program, Sheppard and Enoch Pratt Hospital, Baltimore, MD, USA
| | - Edward B Lee
- Translational Neuropathology Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA
| | - Harvey Levin
- Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA
| | - Jonathan Lifshitz
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, USA; University of Arizona College of Medicine Phoenix, Child Health, Phoenix, AZ, USA; Phoenix Veteran Affairs Healthcare System, Phoenix, AZ, USA
| | - Helen Ling
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - David J Loane
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA; Shock Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA; School of Biochemistry and Immunology and Trinity Biomedical Sciences Institute, Trinity College Dublin, Ireland
| | - Seth Love
- Dementia Research Group, Institute of Clinical Neurosciences, Medical School, University of Bristol, Bristol, UK
| | - Andrew Ir Maas
- Department of Neurosurgery, Antwerp University Hospital and University of Antwerp, Edegem, Belgium
| | - Niklas Marklund
- Skane University Hospital, Department of Clinical Sciences Lund, Neurosurgery, Lund University, Lund, Sweden
| | - Christina L Master
- Center for Injury Research and Prevention and Division of Orthopedic Surgery, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | | | - David F Meaney
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA; Penn Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - David K Menon
- NIHR Global Health Research Group on Neurotrauma, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK; Division of Anaesthesia, Department of Medicine, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK
| | | | - Benoit Mouzon
- Roskamp Institute, Sarasota, Florida, USA; The Open University, Milton Keynes, UK; James A Haley Veterans' Hospital, Tampa, FL, USA
| | - Elliott J Mufson
- Barrow Neurological Institute, Departments of Neurobiology and Neurology, Phoenix, AZ, USA
| | - Joseph O Ojo
- Roskamp Institute, Sarasota, Florida, USA; The Open University, Milton Keynes, UK; James A Haley Veterans' Hospital, Tampa, FL, USA
| | - Mayumi Prins
- UCLA Steve Tisch BrainSPORT Program, Los Angeles, CA, USA
| | - Tamas Revesz
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - Craig W Ritchie
- Centre for Dementia Prevention, University of Edinburgh, Edinburgh, UK
| | - Colin Smith
- Academic Neuropathology, University of Edinburgh, Edinburgh, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Richard Sylvester
- Homerton University Hospital NHS Trust, National Hospital of Neurology and Neurosurgery, University College London, London, UK
| | - Cheuk Y Tang
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John Q Trojanowski
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA; Institute on Aging, University of Pennsylvania, Philadelphia, PA, USA; Center for Neurodegenerative Disease Research, University of Pennsylvania, Philadelphia, PA, USA
| | - Kathryn Urankar
- Dementia Research Group, Institute of Clinical Neurosciences, Medical School, University of Bristol, Bristol, UK
| | - Robert Vink
- Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Cheryl Wellington
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, International Collaboration on Repair Discoveries, School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Elisabeth A Wilde
- Department of Neurology, University of Utah, Salt Lake City, UT, USA; Michael DeBakey VA Medical Center and Baylor College of Medicine, Houston, TX, USA
| | - Lindsay Wilson
- Division of Psychology, University of Stirling, Stirling, UK
| | - Keith Yeates
- Department of Psychology, Alberta Children's Hospital Research Institute and Hotchkiss Brain Institute, University of Calgary, AB, Canada
| | - Douglas H Smith
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA; Penn Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA, USA
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24
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Ritzel RM, Doran SJ, Glaser EP, Meadows VE, Faden AI, Stoica BA, Loane DJ. Old age increases microglial senescence, exacerbates secondary neuroinflammation, and worsens neurological outcomes after acute traumatic brain injury in mice. Neurobiol Aging 2019; 77:194-206. [PMID: 30904769 DOI: 10.1016/j.neurobiolaging.2019.02.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/31/2019] [Accepted: 02/09/2019] [Indexed: 01/10/2023]
Abstract
After traumatic brain injury (TBI), individuals aged over 65 years show increased mortality and worse functional outcomes compared with younger persons. As neuroinflammation is a key pathobiological mechanism of secondary injury after TBI, we examined how aging affects post-traumatic microglial responses and functional outcomes. Young (3-month-old) and aged (18-month-old) male C57Bl/6 mice were subjected to moderate-level controlled cortical impact or sham surgery, and neurological function was evaluated. At 72 hours after injury, brain, blood, and spleen leukocyte counts were assessed ex vivo using flow cytometry. Aged mice demonstrated more severe deficits in forelimb grip strength, balance and motor coordination, spontaneous locomotor activity, and anxiety-like behavior. These animals also exhibited more robust microglial proliferation and significantly higher numbers of brain-infiltrating leukocytes. Microglia in aged mice showed impairments in phagocytic activity and higher production of interleukin-1β (IL-1β). Infiltrating myeloid cells in aged TBI mice also had deficits in phagocytosis but showed diminished proinflammatory cytokine production and greater reactive oxygen species production. Expression of several senescence markers (Bcl-2, p16ink4a, p21cip1a, lipofuscin, and H2AX [pS139]) was increased with age and/or TBI in both microglia and injured cortex. Although there was no difference in the number of circulating blood neutrophils as a function of age, young mice exhibited more pronounced TBI-induced splenomegaly and splenic myeloid cell expansion. Thus, worse post-traumatic behavioral outcomes in aged animals are associated with exaggerated microglial responses, increased leukocyte invasion, and upregulation of senescence markers.
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Affiliation(s)
- Rodney M Ritzel
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sarah J Doran
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ethan P Glaser
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Victoria E Meadows
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA.
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25
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Abstract
Neuroinflammation is initiated as a result of traumatic brain injury and can exacerbate evolving tissue pathology. Immune cells respond to acute signals from damaged cells, initiate neuroinflammation, and drive the pathological consequences over time. Importantly, the mechanism(s) of injury, the location of the immune cells within the brain, and the animal species all contribute to immune cell behavior following traumatic brain injury. Understanding the signals that initiate neuroinflammation and the context in which they appear may be critical for understanding immune cell contributions to pathology and regeneration. Within this paper, we review a number of factors that could affect immune cell behavior acutely following traumatic brain injury.
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Affiliation(s)
- Kathryn L Wofford
- Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania; Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center; School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma, and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA; School of Biochemistry and Immunology and Trinity Biomedical Sciences Institute, Trinity College Dublin, Ireland
| | - D Kacy Cullen
- Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania; Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
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Henry RJ, Doran SJ, Barrett JP, Meadows VE, Sabirzhanov B, Stoica BA, Loane DJ, Faden AI. Inhibition of miR-155 Limits Neuroinflammation and Improves Functional Recovery After Experimental Traumatic Brain Injury in Mice. Neurotherapeutics 2019; 16:216-230. [PMID: 30225790 PMCID: PMC6361054 DOI: 10.1007/s13311-018-0665-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Micro-RNAs (miRs) are short, noncoding RNAs that negatively regulate gene expression at the post-transcriptional level and have been implicated in the pathophysiology of secondary damage after traumatic brain injury (TBI). Among miRs linked to inflammation, miR-155 has been implicated as a pro-inflammatory factor in a variety of organ systems. We examined the expression profile of miR-155, following experimental TBI (controlled cortical impact) in adult male C57Bl/6 mice, as well as the effects of acute or delayed administration of a miR-155 antagomir on post-traumatic neuroinflammatory responses and neurological recovery. Trauma robustly increased miR-155 expression in the injured cortex over 7 days. Similar TBI-induced miR-155 expression changes were also found in microglia/macrophages isolated from the injured cortex at 7 days post-injury. A miR-155 hairpin inhibitor (antagomir; 0.5 nmol), administered intracerebroventricularly (ICV) immediately after injury, attenuated neuroinflammatory markers at both 1 day and 7 days post-injury and reduced impairments in spatial working memory. Delayed ICV infusion of the miR-155 antagomir (0.5 nmol/day), beginning 24 h post-injury and continuing for 6 days, attenuated neuroinflammatory markers at 7 days post-injury and improved motor, but not cognitive, function through 28 days. The latter treatment limited NADPH oxidase 2 expression changes in microglia/macrophages in the injured cortex and reduced cortical lesion volume. In summary, TBI causes a robust and persistent neuroinflammatory response that is associated with increased miR-155 expression in microglia/macrophages, and miR-155 inhibition reduces post-traumatic neuroinflammatory responses and improves neurological recovery. Thus, miR-155 may be a therapeutic target for TBI-related neuroinflammation.
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Affiliation(s)
- Rebecca J. Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
| | - Sarah J. Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
| | - James P. Barrett
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
| | - Victoria E. Meadows
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
| | - Boris Sabirzhanov
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
| | - Bogdan A. Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
| | - David J. Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
- Department of Anesthesiology, University of Maryland School of Medicine, 655 West Baltimore Street, No. 6-011, Baltimore, MD 21201 USA
| | - Alan I. Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD USA
- Department of Anesthesiology, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF No. 6-02, Baltimore, MD 21201 USA
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Doran SJ, Ritzel RM, Glaser EP, Henry RJ, Faden AI, Loane DJ. Sex Differences in Acute Neuroinflammation after Experimental Traumatic Brain Injury Are Mediated by Infiltrating Myeloid Cells. J Neurotrauma 2018; 36:1040-1053. [PMID: 30259790 DOI: 10.1089/neu.2018.6019] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The inflammatory response to moderate-severe controlled cortical impact (CCI) in adult male mice has been shown to exhibit greater glial activation compared with age-matched female mice. However, the relative contributions of resident microglia and infiltrating peripheral myeloid cells to this sexually dimorphic neuroinflammatory responses remains unclear. Here, 12-week-old male and female C57Bl/6 mice were subjected to sham or CCI, and brain samples were collected at 1, 3, or 7 days post-injury for flow cytometry analysis of cytokines, reactive oxygen species (ROS), and phagocytosis in resident microglia (CD45intCD11b+) versus infiltrating myeloid cells (CD45hiCD11b+). Motor (rotarod, cylinder test), affect (open field), and cognitive (Y-maze) function tests also were performed. We demonstrate that male microglia had increased phagocytic activity and higher ROS levels in the non-injured brain, whereas female microglia had increased production of tumor necrosis factor (TNF) α and interleukin (IL)-1β. Following CCI, males showed a significant influx of peripheral myeloid cells by 1 day post-injury followed by proliferation of resident microglia at 3 days. In contrast, myeloid infiltration and microglial activation responses in female CCI mice were significantly reduced. No sex differences were observed for TNFα, IL-1β, transforming growth factor β, NOX2, ROS production, or phagocytic activity in resident microglia or infiltrating cells at any time. However, across these functions, infiltrating myeloid cells were significantly more reactive than resident microglia. Female CCI mice also had improved motor function at 1 day post-injury compared with male mice. Thus, we conclude that sexually dimorphic responses to moderate-severe CCI result from the rapid activation and infiltration of pro-inflammatory myeloid cells to brain in male, but not female, mice.
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Affiliation(s)
- Sarah J Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Rodney M Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Ethan P Glaser
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
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Ritzel RM, Doran SJ, Barrett JP, Henry RJ, Ma EL, Faden AI, Loane DJ. Chronic Alterations in Systemic Immune Function after Traumatic Brain Injury. J Neurotrauma 2018; 35:1419-1436. [PMID: 29421977 DOI: 10.1089/neu.2017.5399] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There is a compelling link between severe brain trauma and immunosuppression in patients with traumatic brain injury (TBI). Although acute changes in the systemic immune compartment have been linked to outcome severity, the long-term consequences of TBI on systemic immune function are unknown. Here, adult male C57Bl/6 mice underwent moderate-level controlled cortical impact (CCI) or sham surgery, and systemic immune function was evaluated at 1, 3, 7, 14, and 60 days post-injury. Bone marrow, blood, thymus, and spleen were examined by flow cytometry to assess changes in immune composition, reactive oxygen species (ROS) production, phagocytic activity, and cytokine production. Bone marrow derived macrophages (BMDMs) from sham and 60-day CCI mice were cultured for immune challenge studies using lipopolysaccharide (LPS) and interleukin-4 (IL-4) models. Acutely, TBI caused robust bone marrow activation and neutrophilia. Neutrophils and monocytes exhibited impairments in respiratory burst, cytokine production, and phagocytosis; in contrast, ROS levels and pro-inflammatory cytokine production were chronically elevated at 60 days post-injury. Cultures of BMDMs from chronic CCI mice demonstrated defects in LPS- and IL-4-induced polarization when compared with stimulated BMDMs from sham mice. TBI also caused thymic involution, inverted CD4:CD8 ratios, chronic T lymphopenia, greater memory conversion, increased T cell activation, impaired interferon γ induction, and chronically elevated Th1 cytokine and ROS production. Collectively, our in-depth phenotypic and functional analyses demonstrate that TBI induces widespread suppression of innate and adaptive immune responses after TBI. Moreover, at chronic time points, TBI mice exhibit hallmarks of accelerated immune aging, displaying chronic deficits in systemic immune function.
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Affiliation(s)
- Rodney M Ritzel
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Sarah J Doran
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - James P Barrett
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Rebecca J Henry
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Elise L Ma
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - David J Loane
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
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Hanscom M, Aubrecht T, Loane DJ, Faden AI, Shea‐Donohue T. Colitis‐Induced Neurobehavioral Deficits Following Chronic Brain Injury. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.921.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marie Hanscom
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - Taryn Aubrecht
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - David J. Loane
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - Alan I. Faden
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - Terez Shea‐Donohue
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMD
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Ma EL, Smith AD, Desai N, Cheung L, Hanscom M, Stoica BA, Loane DJ, Shea-Donohue T, Faden AI. Bidirectional brain-gut interactions and chronic pathological changes after traumatic brain injury in mice. Brain Behav Immun 2017; 66:56-69. [PMID: 28676351 PMCID: PMC5909811 DOI: 10.1016/j.bbi.2017.06.018] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/02/2017] [Accepted: 06/30/2017] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVES Traumatic brain injury (TBI) has complex effects on the gastrointestinal tract that are associated with TBI-related morbidity and mortality. We examined changes in mucosal barrier properties and enteric glial cell response in the gut after experimental TBI in mice, as well as effects of the enteric pathogen Citrobacter rodentium (Cr) on both gut and brain after injury. METHODS Moderate-level TBI was induced in C57BL/6mice by controlled cortical impact (CCI). Mucosal barrier function was assessed by transepithelial resistance, fluorescent-labelled dextran flux, and quantification of tight junction proteins. Enteric glial cell number and activation were measured by Sox10 expression and GFAP reactivity, respectively. Separate groups of mice were challenged with Cr infection during the chronic phase of TBI, and host immune response, barrier integrity, enteric glial cell reactivity, and progression of brain injury and inflammation were assessed. RESULTS Chronic CCI induced changes in colon morphology, including increased mucosal depth and smooth muscle thickening. At day 28 post-CCI, increased paracellular permeability and decreased claudin-1 mRNA and protein expression were observed in the absence of inflammation in the colon. Colonic glial cell GFAP and Sox10 expression were significantly increased 28days after brain injury. Clearance of Cr and upregulation of Th1/Th17 cytokines in the colon were unaffected by CCI; however, colonic paracellular flux and enteric glial cell GFAP expression were significantly increased. Importantly, Cr infection in chronically-injured mice worsened the brain lesion injury and increased astrocyte- and microglial-mediated inflammation. CONCLUSION These experimental studies demonstrate chronic and bidirectional brain-gut interactions after TBI, which may negatively impact late outcomes after brain injury.
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Affiliation(s)
- Elise L Ma
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Allen D Smith
- Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics, and Immunology Laboratory, United States Department of Agriculture (USDA), Beltsville, MD, USA
| | - Neemesh Desai
- Department of Radiation Oncology and Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Lumei Cheung
- Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics, and Immunology Laboratory, United States Department of Agriculture (USDA), Beltsville, MD, USA
| | - Marie Hanscom
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Terez Shea-Donohue
- Department of Radiation Oncology and Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
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Villapol S, Loane DJ, Burns MP. Sexual dimorphism in the inflammatory response to traumatic brain injury. Glia 2017; 65:1423-1438. [PMID: 28608978 DOI: 10.1002/glia.23171] [Citation(s) in RCA: 189] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/19/2022]
Abstract
The activation of resident microglial cells, alongside the infiltration of peripheral macrophages, are key neuroinflammatory responses to traumatic brain injury (TBI) that are directly associated with neuronal death. Sexual disparities in response to TBI have been previously reported; however it is unclear whether a sex difference exists in neuroinflammatory progression after TBI. We exposed male and female mice to moderate-to-severe controlled cortical impact injury and studied glial cell activation in the acute and chronic stages of TBI using immunofluorescence and in situ hybridization analysis. We found that the sex response was completely divergent up to 7 days postinjury. TBI caused a rapid and pronounced cortical microglia/macrophage activation in male mice with a prominent activated phenotype that produced both pro- (IL-1β and TNFα) and anti-inflammatory (Arg1 and TGFβ) cytokines with a single-phase, sustained peak from 1 to 7 days. In contrast, TBI caused a less robust microglia/macrophage phenotype in females with biphasic pro-inflammatory response peaks at 4 h and 7 days, and a delayed anti-inflammatory mRNA peak at 30 days. We further report that female mice were protected against acute cell loss after TBI, with male mice demonstrating enhanced astrogliosis, neuronal death, and increased lesion volume through 7 days post-TBI. Collectively, these findings indicate that TBI leads to a more aggressive neuroinflammatory profile in male compared with female mice during the acute and subacute phases postinjury. Understanding how sex affects the course of neuroinflammation following brain injury is a vital step toward developing personalized and effective treatments for TBI.
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Affiliation(s)
- Sonia Villapol
- Laboratory for Brain Injury and Dementia, Department of Neuroscience, Georgetown University, Washington, District of Columbia
| | - David J Loane
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland
| | - Mark P Burns
- Laboratory for Brain Injury and Dementia, Department of Neuroscience, Georgetown University, Washington, District of Columbia
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Barrett JP, Henry RJ, Villapol S, Stoica BA, Kumar A, Burns MP, Faden AI, Loane DJ. NOX2 deficiency alters macrophage phenotype through an IL-10/STAT3 dependent mechanism: implications for traumatic brain injury. J Neuroinflammation 2017; 14:65. [PMID: 28340575 PMCID: PMC5366128 DOI: 10.1186/s12974-017-0843-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/16/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND NADPH oxidase (NOX2) is an enzyme system that generates reactive oxygen species (ROS) in microglia and macrophages. Excessive ROS production is linked with neuroinflammation and chronic neurodegeneration following traumatic brain injury (TBI). Redox signaling regulates macrophage/microglial phenotypic responses (pro-inflammatory versus anti-inflammatory), and NOX2 inhibition following moderate-to-severe TBI markedly reduces pro-inflammatory activation of macrophages/microglia resulting in concomitant increases in anti-inflammatory responses. Here, we report the signaling pathways that regulate NOX2-dependent macrophage/microglial phenotype switching in the TBI brain. METHODS Bone marrow-derived macrophages (BMDMs) prepared from wildtype (C57Bl/6) and NOX2 deficient (NOX2-/-) mice were treated with lipopolysaccharide (LPS; 10 ng/ml), interleukin-4 (IL-4; 10 ng/ml), or combined LPS/IL-4 to investigate signal transduction pathways associated with macrophage activation using western immunoblotting and qPCR analyses. Signaling pathways and activation markers were evaluated in ipsilateral cortical tissue obtained from adult male wildtype and NOX2-/- mice that received moderate-level controlled cortical impact (CCI). A neutralizing anti-IL-10 approach was used to determine the effects of IL-10 on NOX2-dependent transitions from pro- to anti-inflammatory activation states. RESULTS Using an LPS/IL-4-stimulated BMDM model that mimics the mixed pro- and anti-inflammatory responses observed in the injured cortex, we show that NOX2-/- significantly reduces STAT1 signaling and markers of pro-inflammatory activation. In addition, NOX2-/- BMDMs significantly increase anti-inflammatory marker expression; IL-10-mediated STAT3 signaling, but not STAT6 signaling, appears to be critical in regulating this anti-inflammatory response. Following moderate-level CCI, IL-10 is significantly increased in microglia/macrophages in the injured cortex of NOX2-/- mice. These changes are associated with increased STAT3 activation, but not STAT6 activation, and a robust anti-inflammatory response. Neutralization of IL-10 in NOX2-/- BMDMs or CCI mice blocks STAT3 activation and the anti-inflammatory response, thereby demonstrating a critical role for IL-10 in regulating NOX2-dependent transitions between pro- and anti-inflammatory activation states. CONCLUSIONS These studies indicate that following TBI NOX2 inhibition promotes a robust anti-inflammatory response in macrophages/microglia that is mediated by the IL-10/STAT3 signaling pathway. Thus, therapeutic interventions that inhibit macrophage/microglial NOX2 activity may improve TBI outcomes by not only limiting pro-inflammatory neurotoxic responses, but also enhancing IL-10-mediated anti-inflammatory responses that are neuroprotective.
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Affiliation(s)
- James P Barrett
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD, 21201, USA
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD, 21201, USA
| | - Sonia Villapol
- Laboratory for Brain Injury and Dementia, Department of Neuroscience, Georgetown University, Washington, DC, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD, 21201, USA
| | - Alok Kumar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD, 21201, USA
| | - Mark P Burns
- Laboratory for Brain Injury and Dementia, Department of Neuroscience, Georgetown University, Washington, DC, USA
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD, 21201, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD, 21201, USA.
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Kumar A, Stoica BA, Loane DJ, Yang M, Abulwerdi G, Khan N, Kumar A, Thom SR, Faden AI. Microglial-derived microparticles mediate neuroinflammation after traumatic brain injury. J Neuroinflammation 2017; 14:47. [PMID: 28292310 PMCID: PMC5351060 DOI: 10.1186/s12974-017-0819-4] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 02/18/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Local and systemic inflammatory responses are initiated early after traumatic brain injury (TBI), and may play a key role in the secondary injury processes resulting in neuronal loss and neurological deficits. However, the mechanisms responsible for the rapid expansion of neuroinflammation and its long-term progression have yet to be elucidated. Here, we investigate the role of microparticles (MP), a member of the extracellular vesicle family, in the exchange of pro-inflammatory molecules between brain immune cells, as well as their transfer to the systemic circulation, as key pathways of inflammation propagation following brain trauma. METHODS Adult male C57BL/6 mice were subjected to controlled cortical impact TBI for 24 h, and enriched MP were isolated in the blood, while neuroinflammation was assessed in the TBI cortex. MP were characterized by flow cytometry, and MP content was assayed using gene and protein markers for pro-inflammatory mediators. Enriched MP co-cultured with BV2 or primary microglial cells were used for immune propagation assays. Enriched MP from BV2 microglia or CD11b-positive microglia from the TBI brain were stereotactically injected into the cortex of uninjured mice to evaluate MP-related seeding of neuroinflammation in vivo. RESULTS As the neuroinflammatory response is developing in the brain after TBI, microglial-derived MP are released into the circulation. Circulating enriched MP from the TBI animals can activate microglia in vitro. Lipopolysaccharide stimulation increases MP release from microglia in vitro and enhances their content of pro-inflammatory mediators, interleukin-1β and microRNA-155. Enriched MP from activated microglia in vitro or CD11b-isolated microglia/macrophage from the TBI brain ex vivo are sufficient to initiate neuroinflammation following their injection into the cortex of naïve (uninjured) animals. CONCLUSIONS These data provide further insights into the mechanisms underlying the development and dissemination of neuroinflammation after TBI. MP loaded with pro-inflammatory molecules initially released by microglia following trauma can activate additional microglia that may contribute to progressive neuroinflammatory response in the injured brain, as well as stimulate systemic immune responses. Due to their ability to independently initiate inflammatory responses, MP derived from activated microglia may provide a potential therapeutic target for other neurological disorders in which neuroinflammation may be a contributing factor.
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Affiliation(s)
- Alok Kumar
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA
| | - Bogdan A Stoica
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA
| | - David J Loane
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA
| | - Ming Yang
- Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Gelareh Abulwerdi
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA
| | - Niaz Khan
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA
| | - Asit Kumar
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA
| | - Stephen R Thom
- Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alan I Faden
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA. .,Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20 Penn Street, Baltimore, MD, 21201, USA.
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Simon DW, McGeachy MJ, Bayır H, Clark RSB, Loane DJ, Kochanek PM. The far-reaching scope of neuroinflammation after traumatic brain injury. Nat Rev Neurol 2017; 13:171-191. [PMID: 28186177 DOI: 10.1038/nrneurol.2017.13] [Citation(s) in RCA: 554] [Impact Index Per Article: 79.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The 'silent epidemic' of traumatic brain injury (TBI) has been placed in the spotlight as a result of clinical investigations and popular press coverage of athletes and veterans with single or repetitive head injuries. Neuroinflammation can cause acute secondary injury after TBI, and has been linked to chronic neurodegenerative diseases; however, anti-inflammatory agents have failed to improve TBI outcomes in clinical trials. In this Review, we therefore propose a new framework of targeted immunomodulation after TBI for future exploration. Our framework incorporates factors such as the time from injury, mechanism of injury, and secondary insults in considering potential treatment options. Structuring our discussion around the dynamics of the immune response to TBI - from initial triggers to chronic neuroinflammation - we consider the ability of soluble and cellular inflammatory mediators to promote repair and regeneration versus secondary injury and neurodegeneration. We summarize both animal model and human studies, with clinical data explicitly defined throughout this Review. Recent advances in neuroimmunology and TBI-responsive neuroinflammation are incorporated, including concepts of inflammasomes, mechanisms of microglial polarization, and glymphatic clearance. Moreover, we highlight findings that could offer novel therapeutic targets for translational and clinical research, assimilate evidence from other brain injury models, and identify outstanding questions in the field.
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Affiliation(s)
- Dennis W Simon
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, 4401 Penn Avenue, Pittsburgh, Pennsylvania 15224, USA
| | - Mandy J McGeachy
- Department of Medicine, University of Pittsburgh School of Medicine, 3500 Terrace Street, BST South, S719, Pittsburgh, Pennsylvania 15261, USA
| | - Hülya Bayır
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, 4401 Penn Avenue, Pittsburgh, Pennsylvania 15224, USA
| | - Robert S B Clark
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, 4401 Penn Avenue, Pittsburgh, Pennsylvania 15224, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, Maryland 21201, USA
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, 3434 Fifth Avenue, Pittsburgh, Pennsylvania 15260, USA
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Fe Lanfranco M, Loane DJ, Mocchetti I, Burns MP, Villapol S. Combination of Fluorescent in situ Hybridization (FISH) and Immunofluorescence Imaging for Detection of Cytokine Expression in Microglia/Macrophage Cells. Bio Protoc 2017; 7:e2608. [PMID: 29238736 DOI: 10.21769/bioprotoc.2608] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Microglia and macrophage cells are the primary producers of cytokines in response to neuroinflammatory processes. But these cytokines are also produced by other glial cells, endothelial cells, and neurons. It is essential to identify the cells that produce these cytokines to target their different levels of activation. We used dual RNAscope® fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) techniques to visualize the mRNA expression pattern of pro- and anti-inflammatory cytokines in microglia/macrophages cells. Using these methods, we can associate one mRNA to specific cell types when combining with different cellular markers by immunofluorescence. Results from RNAscope® probes IL-1β, TNFα, TGFβ, IL-10 or Arg1, showed colocalization with antibodies for microglia/macrophage cells. These target probes showed adequate sensitivity and specificity to detect mRNA expression. New FISH detection techniques combined with immunohistochemical techniques will help to jointly determine the protein and mRNA localization, as well as provide reliable quantification of the mRNA expression levels.
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Affiliation(s)
- Maria Fe Lanfranco
- Department of Neuroscience, Georgetown University, Washington, DC, United States
| | - David J Loane
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, United States
| | - Italo Mocchetti
- Department of Neuroscience, Georgetown University, Washington, DC, United States
| | - Mark P Burns
- Department of Neuroscience, Georgetown University, Washington, DC, United States
| | - Sonia Villapol
- Department of Neuroscience, Georgetown University, Washington, DC, United States
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Kumar A, Barrett JP, Alvarez-Croda DM, Stoica BA, Faden AI, Loane DJ. NOX2 drives M1-like microglial/macrophage activation and neurodegeneration following experimental traumatic brain injury. Brain Behav Immun 2016; 58:291-309. [PMID: 27477920 PMCID: PMC5067217 DOI: 10.1016/j.bbi.2016.07.158] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/20/2016] [Accepted: 07/27/2016] [Indexed: 12/16/2022] Open
Abstract
Following traumatic brain injury (TBI), activation of microglia and peripherally derived inflammatory macrophages occurs in association with tissue damage. This neuroinflammatory response may have beneficial or detrimental effects on neuronal survival, depending on the functional polarization of these cells along a continuum from M1-like to M2-like activation states. The mechanisms that regulate M1-like and M2-like activation after TBI are not well understood, but appear in part to reflect the redox state of the lesion microenvironment. NADPH oxidase (NOX2) is a critical enzyme system that generates reactive oxygen species in microglia/macrophages. After TBI, NOX2 is strongly up-regulated in M1-like, but not in M2-like polarized cells. Therefore, we hypothesized that NOX2 drives M1-like neuroinflammation and contributes to neurodegeneration and loss of neurological function after TBI. In the present studies we inhibited NOX2 activity using NOX2-knockout mice or the selective peptide inhibitor gp91ds-tat. We show that NOX2 is highly up-regulated in infiltrating macrophages after injury, and that NOX2 deficiency reduces markers of M1-like activation, limits tissue loss and neurodegeneration, and improves motor recovery after moderate-level control cortical injury (CCI). NOX2 deficiency also promotes M2-like activation after CCI, through increased IL-4Rα signaling in infiltrating macrophages, suggesting that NOX2 acts as a critical switch between M1- and M2-like activation states after TBI. Administration of gp91ds-tat to wild-type CCI mice starting at 24h post-injury reduces deficits in cognitive function and increased M2-like activation in the hippocampus. Collectively, our data indicate that increased NOX2 activity after TBI drives M1-like activation that contributes to inflammatory-mediated neurodegeneration, and that inhibiting this pathway provides neuroprotection, in part by altering M1-/M2-like balance towards the M2-like neuroinflammatory response.
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Affiliation(s)
- Alok Kumar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - James P. Barrett
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Dulce-Mariely Alvarez-Croda
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA,Posgrado en Neuroetologia, Universidad Veracruzana, Xalapa, Mexico,Centro de Investigaciones Cerebrales, Universidad Veracruzana, Xalapa, Mexico
| | - Bogdan A. Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alan I. Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J. Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA,Correspondence: David J. Loane PhD, Department of Anesthesiology, University of Maryland School of Medicine, 655 West Baltimore Street, #6-011, Baltimore, MD 21201. Tel: 410-706-5188 Fax: 410-706-1639,
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Long A, Park JH, Klimova N, Fowler C, Loane DJ, Kristian T. CD38 Knockout Mice Show Significant Protection Against Ischemic Brain Damage Despite High Level Poly-ADP-Ribosylation. Neurochem Res 2016; 42:283-293. [PMID: 27518087 DOI: 10.1007/s11064-016-2031-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 12/22/2022]
Abstract
Several enzymes in cellular bioenergetics metabolism require NAD+ as an essential cofactor for their activity. NAD+ depletion following ischemic insult can result in cell death and has been associated with over-activation of poly-ADP-ribose polymerase PARP1 as well as an increase in NAD+ consuming enzyme CD38. CD38 is an NAD+ glycohydrolase that plays an important role in inflammatory responses. To determine the contribution of CD38 activity to the mechanisms of post-ischemic brain damage we subjected CD38 knockout (CD38KO) mice and wild-type (WT) mice to transient forebrain ischemia. The CD38KO mice showed a significant amelioration in both histological and neurologic outcome following ischemic insult. Decrease of hippocampal NAD+ levels detected during reperfusion in WT mice was only transient in CD38KO animals, suggesting that CD38 contributes to post-ischemic NAD+ catabolism. Surprisingly, pre-ischemic poly-ADP-ribose (PAR) levels were dramatically higher in CD38KO animals compared to WT animals and exhibited reduction post-ischemia in contrast to the increased levels in WT animals. The high PAR levels in CD38 mice were due to reduced expression levels of poly-ADP-ribose glycohydrolase (PARG). Thus, the absence of CD38 activity can not only directly affect inflammatory response, but also result in unpredicted alterations in the expression levels of enzymes participating in NAD+ metabolism. Although the CD38KO mice showed significant protection against ischemic brain injury, the changes in enzyme activity related to NAD+ metabolism makes the determination of the role of CD38 in mechanisms of ischemic brain damage more complex.
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Affiliation(s)
- Aaron Long
- Veterans Affairs Maryland Health Care System, 10 North Greene Street, Baltimore, MD, 21201, USA
| | - Ji H Park
- Veterans Affairs Maryland Health Care System, 10 North Greene Street, Baltimore, MD, 21201, USA
| | - Nina Klimova
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research, School of Medicine, University of Maryland, 685 West Baltimore Street, MSTF 534, Baltimore, MD, 21201, USA
| | - Carol Fowler
- Veterans Affairs Maryland Health Care System, 10 North Greene Street, Baltimore, MD, 21201, USA
| | - David J Loane
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research, School of Medicine, University of Maryland, 685 West Baltimore Street, MSTF 534, Baltimore, MD, 21201, USA
| | - Tibor Kristian
- Veterans Affairs Maryland Health Care System, 10 North Greene Street, Baltimore, MD, 21201, USA. .,Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research, School of Medicine, University of Maryland, 685 West Baltimore Street, MSTF 534, Baltimore, MD, 21201, USA.
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Wu J, Zhao Z, Kumar A, Lipinski MM, Loane DJ, Stoica BA, Faden AI. Endoplasmic Reticulum Stress and Disrupted Neurogenesis in the Brain Are Associated with Cognitive Impairment and Depressive-Like Behavior after Spinal Cord Injury. J Neurotrauma 2016; 33:1919-1935. [PMID: 27050417 DOI: 10.1089/neu.2015.4348] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Clinical and experimental studies show that spinal cord injury (SCI) can cause cognitive impairment and depression that can significantly impact outcomes. Thus, identifying mechanisms responsible for these less well-examined, important SCI consequences may provide targets for more effective therapeutic intervention. To determine whether cognitive and depressive-like changes correlate with injury severity, we exposed mice to sham, mild, moderate, or severe SCI using the Infinite Horizon Spinal Cord Impactor and evaluated performance on a variety of neurobehavioral tests that are less dependent on locomotion. Cognitive impairment in Y-maze, novel objective recognition, and step-down fear conditioning tasks were increased in moderate- and severe-injury mice that also displayed depressive-like behavior as quantified in the sucrose preference, tail suspension, and forced swim tests. Bromo-deoxyuridine incorporation with immunohistochemistry revealed that SCI led to a long-term reduction in the number of newly-generated immature neurons in the hippocampal dentate gyrus, accompanied by evidence of greater neuronal endoplasmic reticulum (ER) stress. Stereological analysis demonstrated that moderate/severe SCI reduced neuronal survival and increased the number of activated microglia chronically in the cerebral cortex and hippocampus. The potent microglial activator cysteine-cysteine chemokine ligand 21 (CCL21) was elevated in the brain sites after SCI in association with increased microglial activation. These findings indicate that SCI causes chronic neuroinflammation that contributes to neuronal loss, impaired hippocampal neurogenesis and increased neuronal ER stress in important brain regions associated with cognitive decline and physiological depression. Accumulation of CCL21 in brain may subserve a pathophysiological role in cognitive changes and depression after SCI.
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Affiliation(s)
- Junfang Wu
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Zaorui Zhao
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Alok Kumar
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Marta M Lipinski
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - David J Loane
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Bogdan A Stoica
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine , Baltimore, Maryland
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Kumar A, Alvarez-Croda DM, Stoica BA, Faden AI, Loane DJ. Microglial/Macrophage Polarization Dynamics following Traumatic Brain Injury. J Neurotrauma 2015; 33:1732-1750. [PMID: 26486881 DOI: 10.1089/neu.2015.4268] [Citation(s) in RCA: 214] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Activated microglia and macrophages exert dual beneficial and detrimental roles after central nervous system injury, which are thought to be due to their polarization along a continuum from a classical pro-inflammatory M1-like state to an alternative anti-inflammatory M2-like state. The goal of the present study was to analyze the temporal dynamics of microglia/macrophage polarization within the lesion micro-environment following traumatic brain injury (TBI) using a moderate-level controlled cortical impact (CCI) model in mice. We performed a detailed phenotypic analysis of M1- and M2-like polarized microglia/macrophages, as well as nicotinamide adenine dinucleotide phosphate oxidase (NOX2) expression, through 7 days post-injury using real-time polymerase chain reaction (qPCR), flow cytometry and image analyses. We demonstrated that microglia/macrophages express both M1- and M2-like phenotypic markers early after TBI, but the transient up-regulation of the M2-like phenotype was replaced by a predominant M1- or mixed transitional (Mtran) phenotype that expressed high levels of NOX2 at 7 days post-injury. The shift towards the M1-like and Mtran phenotype was associated with increased cortical and hippocampal neurodegeneration. In a follow up study, we administered a selective NOX2 inhibitor, gp91ds-tat, to CCI mice starting at 24 h post-injury to investigate the relationship between NOX2 and M1-like/Mtran phenotypes. Delayed gp91ds-tat treatment altered M1-/M2-like balance in favor of the anti-inflammatory M2-like phenotype, and significantly reduced oxidative damage in neurons at 7 days post-injury. Therefore, our data suggest that despite M1-like and M2-like polarized microglia/macrophages being activated after TBI, the early M2-like response becomes dysfunctional over time, resulting in development of pathological M1-like and Mtran phenotypes driven by increased NOX2 activity.
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Affiliation(s)
- Alok Kumar
- 1 Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Dulce-Mariely Alvarez-Croda
- 1 Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland.,2 Posgrado en Neuroetologia, Universidad Veracruzana , Xalapa, Mexico
| | - Bogdan A Stoica
- 1 Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Alan I Faden
- 1 Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - David J Loane
- 1 Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
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Kabadi SV, Stoica BA, Zimmer DB, Afanador L, Duffy KB, Loane DJ, Faden AI. S100B inhibition reduces behavioral and pathologic changes in experimental traumatic brain injury. J Cereb Blood Flow Metab 2015; 35:2010-20. [PMID: 26154869 PMCID: PMC4671122 DOI: 10.1038/jcbfm.2015.165] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 06/10/2015] [Accepted: 06/12/2015] [Indexed: 01/13/2023]
Abstract
Neuroinflammation following traumatic brain injury (TBI) is increasingly recognized to contribute to chronic tissue loss and neurologic dysfunction. Circulating levels of S100B increase after TBI and have been used as a biomarker. S100B is produced by activated astrocytes and can promote microglial activation; signaling by S100B through interaction with the multiligand advanced glycation end product-specific receptor (AGER) has been implicated in brain injury and microglial activation during chronic neurodegeneration. We examined the effects of S100B inhibition in a controlled cortical impact model, using S100B knockout mice or administration of neutralizing S100B antibody. Both interventions significantly reduced TBI-induced lesion volume, improved retention memory function, and attenuated microglial activation. The neutralizing antibody also significantly reduced sensorimotor deficits and improved neuronal survival in the cortex. However, S100B did not alter microglial activation in BV2 cells or primary microglial cultures stimulated by lipopolysaccharide or interferon gamma. Further, proximity ligation assays did not support direct interaction in the brain between S100B and AGER following TBI. Future studies are needed to elucidate specific pathways underlying S100B-mediated neuroinflammatory actions after TBI. Our results strongly implicate S100B in TBI-induced neuroinflammation, cell loss, and neurologic dysfunction, thereby indicating that it is a potential therapeutic target for TBI.
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Affiliation(s)
- Shruti V Kabadi
- Center for Shock, Trauma and Anesthesiology Research (STAR) and Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bogdan A Stoica
- Center for Shock, Trauma and Anesthesiology Research (STAR) and Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Danna B Zimmer
- Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Lauriaselle Afanador
- Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kara B Duffy
- Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - David J Loane
- Center for Shock, Trauma and Anesthesiology Research (STAR) and Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Alan I Faden
- Center for Shock, Trauma and Anesthesiology Research (STAR) and Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Sabirzhanov B, Stoica BA, Zhao Z, Loane DJ, Wu J, Dorsey SG, Faden AI. miR-711 upregulation induces neuronal cell death after traumatic brain injury. Cell Death Differ 2015; 23:654-68. [PMID: 26470728 DOI: 10.1038/cdd.2015.132] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/18/2015] [Accepted: 09/03/2015] [Indexed: 11/09/2022] Open
Abstract
Traumatic brain injury (TBI) is a leading cause of mortality and disability. MicroRNAs (miRs) are small noncoding RNAs that negatively regulate gene expression at post-transcriptional level and may be key modulators of neuronal apoptosis, yet their role in secondary injury after TBI remains largely unexplored. Changes in miRs after controlled cortical impact (CCI) in mice were examined during the first 72 h using miR arrays and qPCR. One selected miR (711) was examined with regard to its regulation and relation to cell death; effects of miR-711 modulation were evaluated after CCI and using in vitro cell death models of primary cortical neurons. Levels of miR-711 were increased in the cortex early after TBI and in vitro models through rapid upregulation of miR-711 transcription (pri-miR-711) rather than catabolism. Increases coincided with downregulation of the pro-survival protein Akt, a predicted target of miR-711, with sequential activation of forkhead box O3 (FoxO3)a/glycogen synthase kinase 3 (GSK3)α/β, pro-apoptotic BH3-only molecules PUMA (Bcl2-binding component 3) and Bim (Bcl2-like 11 (apoptosis facilitator)), and mitochondrial release of cytochrome c and AIF. miR-711 and Akt (mRNA) co-immunoprecipitated with the RNA-induced silencing complex (RISC). A miR-711 hairpin inhibitor attenuated the apoptotic mechanisms and decreased neuronal death in an Akt-dependent manner. Conversely, a miR-711 mimic enhanced neuronal apoptosis. Central administration of the miR-711 hairpin inhibitor after TBI increased Akt expression and attenuated apoptotic pathways. Treatment reduced cortical lesion volume, neuronal cell loss in cortex and hippocampus, and long-term neurological dysfunction. miR-711 changes contribute to neuronal cell death after TBI, in part by inhibiting Akt, and may serve as a novel therapeutic target.
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Affiliation(s)
- B Sabirzhanov
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - B A Stoica
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Z Zhao
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - D J Loane
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - J Wu
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - S G Dorsey
- University of Maryland School of Nursing, Baltimore, MD, USA.,Program in Neuroscience, University of Maryland, Baltimore, MD, USA
| | - A I Faden
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
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Loane DJ, Kumar A. Microglia in the TBI brain: The good, the bad, and the dysregulated. Exp Neurol 2015; 275 Pt 3:316-327. [PMID: 26342753 DOI: 10.1016/j.expneurol.2015.08.018] [Citation(s) in RCA: 460] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 08/05/2015] [Accepted: 08/25/2015] [Indexed: 01/24/2023]
Abstract
As the major cellular component of the innate immune system in the central nervous system (CNS) and the first line of defense whenever injury or disease occurs, microglia play a critical role in neuroinflammation following a traumatic brain injury (TBI). In the injured brain microglia can produce neuroprotective factors, clear cellular debris and orchestrate neurorestorative processes that are beneficial for neurological recovery after TBI. However, microglia can also become dysregulated and can produce high levels of pro-inflammatory and cytotoxic mediators that hinder CNS repair and contribute to neuronal dysfunction and cell death. The dual role of microglial activation in promoting beneficial and detrimental effects on neurons may be accounted for by their polarization state and functional responses after injury. In this review article we discuss emerging research on microglial activation phenotypes in the context of acute brain injury, and the potential role of microglia in phenotype-specific neurorestorative processes such as neurogenesis, angiogenesis, oligodendrogenesis and regeneration. We also describe some of the known molecular mechanisms that regulate phenotype switching, and highlight new therapeutic approaches that alter microglial activation state balance to enhance long-term functional recovery after TBI. An improved understanding of the regulatory mechanisms that control microglial phenotypic shifts may advance our knowledge of post-injury recovery and repair, and provide opportunities for the development of novel therapeutic strategies for TBI.
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Affiliation(s)
- David J Loane
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, United States; Shock, Trauma, and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Alok Kumar
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, United States; Shock, Trauma, and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, United States
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Faden AI, Wu J, Stoica BA, Loane DJ. Progressive inflammation-mediated neurodegeneration after traumatic brain or spinal cord injury. Br J Pharmacol 2015; 173:681-91. [PMID: 25939377 DOI: 10.1111/bph.13179] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/31/2015] [Accepted: 04/14/2015] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) has been linked to dementia and chronic neurodegeneration. Described initially in boxers and currently recognized across high contact sports, the association between repeated concussion (mild TBI) and progressive neuropsychiatric abnormalities has recently received widespread attention, and has been termed chronic traumatic encephalopathy. Less well appreciated are cognitive changes associated with neurodegeneration in the brain after isolated spinal cord injury. Also under-recognized is the role of sustained neuroinflammation after brain or spinal cord trauma, even though this relationship has been known since the 1950s and is supported by more recent preclinical and clinical studies. These pathological mechanisms, manifested by extensive microglial and astroglial activation and appropriately termed chronic traumatic brain inflammation or chronic traumatic inflammatory encephalopathy, may be among the most important causes of post-traumatic neurodegeneration in terms of prevalence. Importantly, emerging experimental work demonstrates that persistent neuroinflammation can cause progressive neurodegeneration that may be treatable even weeks after traumatic injury.
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Affiliation(s)
- Alan I Faden
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Junfang Wu
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
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Abstract
Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Despite extensive preclinical research supporting the effectiveness of neuroprotective therapies for brain trauma, there have been no successful randomized controlled clinical trials to date. TBI results in delayed secondary tissue injury due to neurochemical, metabolic and cellular changes; modulating such effects has provided the basis for neuroprotective interventions. To establish more effective neuroprotective treatments for TBI it is essential to better understand the complex cellular and molecular events that contribute to secondary injury. Here we critically review relevant research related to causes and modulation of delayed tissue damage, with particular emphasis on cell death mechanisms and post-traumatic neuroinflammation. We discuss the concept of utilizing multipotential drugs that target multiple secondary injury pathways, rather than more specific "laser"-targeted strategies that have uniformly failed in clinical trials. Moreover, we assess data supporting use of neuroprotective drugs that are currently being evaluated in human clinical trials for TBI, as well as promising emerging experimental multipotential drug treatment strategies. Finally, we describe key challenges and provide suggestions to improve the likelihood of successful clinical translation.
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Affiliation(s)
- David J Loane
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), National Study Center for Trauma and EMS, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), National Study Center for Trauma and EMS, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), National Study Center for Trauma and EMS, University of Maryland School of Medicine, Baltimore, MD, USA.
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Faden AI, Loane DJ. Chronic neurodegeneration after traumatic brain injury: Alzheimer disease, chronic traumatic encephalopathy, or persistent neuroinflammation? Neurotherapeutics 2015; 12:143-50. [PMID: 25421001 PMCID: PMC4322076 DOI: 10.1007/s13311-014-0319-5] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
It has long been suggested that prior traumatic brain injury (TBI) increases the subsequent incidence of chronic neurodegenerative disorders, including Alzheimer disease, Parkinson disease, and amyotrophic lateral sclerosis. Among these, the association with Alzheimer disease has the strongest support. There is also a long-recognized association between repeated concussive insults and progressive cognitive decline or other neuropsychiatric abnormalities. The latter was first described in boxers as dementia pugilistica, and has received widespread recent attention in contact sports such as professional American football. The term chronic traumatic encephalopathy was coined to attempt to define a "specific" entity marked by neurobehavioral changes and the extensive deposition of phosphorylated tau protein. Nearly lost in the discussions of post-traumatic neurodegeneration after traumatic brain injury has been the role of sustained neuroinflammation, even though this association has been well established pathologically since the 1950s, and is strongly supported by subsequent preclinical and clinical studies. Manifested by extensive microglial and astroglial activation, such chronic traumatic brain inflammation may be the most important cause of post-traumatic neurodegeneration in terms of prevalence. Critically, emerging preclinical studies indicate that persistent neuroinflammation and associated neurodegeneration may be treatable long after the initiating insult(s).
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Affiliation(s)
- Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247 20, Penn Street, Baltimore, MD, 21201, USA,
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Loane DJ, Stoica BA, Tchantchou F, Kumar A, Barrett JP, Akintola T, Xue F, Conn PJ, Faden AI. Novel mGluR5 positive allosteric modulator improves functional recovery, attenuates neurodegeneration, and alters microglial polarization after experimental traumatic brain injury. Neurotherapeutics 2014; 11:857-69. [PMID: 25096154 PMCID: PMC4391388 DOI: 10.1007/s13311-014-0298-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Traumatic brain injury (TBI) causes microglial activation and related neurotoxicity that contributes to chronic neurodegeneration and loss of neurological function. Selective activation of metabotropic glutamate receptor 5 (mGluR5) by the orthosteric agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG), is neuroprotective in experimental models of TBI, and has potent anti-inflammatory effects in vitro. However, the therapeutic potential of CHPG is limited due to its relatively weak potency and brain permeability. Highly potent, selective and brain penetrant mGluR5 positive allosteric modulators (PAMs) have been developed and show promise as therapeutic agents. We evaluated the therapeutic potential of a novel mGluR5 PAM, VU0360172, after controlled cortical impact (CCI) in mice. Vehicle, VU0360172, or VU0360172 plus mGluR5 antagonist (MTEP), were administered systemically to CCI mice at 3 h post-injury; lesion volume, hippocampal neurodegeneration, microglial activation, and functional recovery were assessed through 28 days post-injury. Anti-inflammatory effects of VU0360172 were also examined in vitro using BV2 and primary microglia. VU0360172 treatment significantly reduced the lesion, attenuated hippocampal neurodegeneration, and improved motor function recovery after CCI. Effects were mediated by mGluR5 as co-administration of MTEP blocked the protective effects of VU0360172. VU0360172 significantly reduced CD68 and NOX2 expression in activated microglia in the cortex at 28 days post-injury, and also suppressed pro-inflammatory signaling pathways in BV2 and primary microglia. In addition, VU0360172 treatment shifted the balance between M1/M2 microglial activation states towards an M2 pro-repair phenotype. This study demonstrates that VU0360172 confers neuroprotection after experimental TBI, and suggests that mGluR5 PAMs may be promising therapeutic agents for head injury.
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Affiliation(s)
- David J. Loane
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
| | - Bogdan A. Stoica
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
| | - Flaubert Tchantchou
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
| | - Alok Kumar
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
| | - James P. Barrett
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
| | - Titilola Akintola
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
| | - Fengtian Xue
- />Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD USA
| | - P. Jeffrey Conn
- />Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN USA
| | - Alan I. Faden
- />Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Health Sciences Facility II (HSFII), #S247, 20 Penn Street, Baltimore, MD 21201 USA
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Stoica BA, Loane DJ, Zhao Z, Kabadi SV, Hanscom M, Byrnes KR, Faden AI. PARP-1 inhibition attenuates neuronal loss, microglia activation and neurological deficits after traumatic brain injury. J Neurotrauma 2014; 31:758-72. [PMID: 24476502 DOI: 10.1089/neu.2013.3194] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Traumatic brain injury (TBI) causes neuronal cell death as well as microglial activation and related neurotoxicity that contribute to subsequent neurological dysfunction. Poly (ADP-ribose) polymerase (PARP-1) induces neuronal cell death through activation of caspase-independent mechanisms, including release of apoptosis inducing factor (AIF), and microglial activation. Administration of PJ34, a selective PARP-1 inhibitor, reduced cell death of primary cortical neurons exposed to N-Methyl-N'-Nitro-N-Nitrosoguanidine (MNNG), a potent inducer of AIF-dependent cell death. PJ34 also attenuated lipopolysaccharide and interferon-γ-induced activation of BV2 or primary microglia, limiting NF-κB activity and iNOS expression as well as decreasing generation of reactive oxygen species and TNFα. Systemic administration of PJ34 starting as late as 24 h after controlled cortical impact resulted in improved motor function recovery in mice with TBI. Stereological analysis demonstrated that PJ34 treatment reduced the lesion volume, attenuated neuronal cell loss in the cortex and thalamus, and reduced microglial activation in the TBI cortex. PJ34 treatment did not improve cognitive performance in a Morris water maze test or reduce neuronal cell loss in the hippocampus. Overall, our data indicate that PJ34 has a significant, albeit selective, neuroprotective effect after experimental TBI, and its therapeutic effect may be from multipotential actions on neuronal cell death and neuroinflammatory pathways.
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Affiliation(s)
- Bogdan A Stoica
- 1 Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), National Study Center for Trauma and EMS, University of Maryland , School of Medicine, Baltimore, Maryland
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Winston CN, Chellappa D, Wilkins T, Barton DJ, Washington PM, Loane DJ, Zapple DN, Burns MP. Controlled cortical impact results in an extensive loss of dendritic spines that is not mediated by injury-induced amyloid-beta accumulation. J Neurotrauma 2013; 30:1966-72. [PMID: 23879560 DOI: 10.1089/neu.2013.2960] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The clinical manifestations that occur after traumatic brain injury (TBI) include a wide range of cognitive, emotional, and behavioral deficits. The loss of excitatory synapses could potentially explain why such diverse symptoms occur after TBI, and a recent preclinical study has demonstrated a loss of dendritic spines, the postsynaptic site of the excitatory synapse, after fluid percussion injury. The objective of this study was to determine if controlled cortical impact (CCI) also resulted in dendritic spine retraction and to probe the underlying mechanisms of this spine loss. We used a unilateral CCI and visualized neurons and dendtritic spines at 24 h post-injury using Golgi stain. We found that TBI caused a 32% reduction of dendritic spines in layer II/III of the ipsilateral cortex and a 20% reduction in the dendritic spines of the ipsilateral dentate gyrus. Spine loss was not restricted to the ipsilateral hemisphere, however, with similar reductions in spine numbers recorded in the contralateral cortex (25% reduction) and hippocampus (23% reduction). Amyloid-β (Aβ), a neurotoxic peptide commonly associated with Alzheimer disease, accumulates rapidly after TBI and is also known to cause synaptic loss. To determine if Aβ contributes to spine loss after brain injury, we administered a γ-secretase inhibitor LY450139 after TBI. We found that while LY450139 administration could attenuate the TBI-induced increase in Aβ, it had no effect on dendritic spine loss after TBI. We conclude that the acute, global loss of dendritic spines after TBI is independent of γ-secretase activity or TBI-induced Aβ accumulation.
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Affiliation(s)
- Charisse N Winston
- 1 Department of Neuroscience, Laboratory for Brain Injury and Dementia, Georgetown University Medical Center , Washington, DC
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Loane DJ, Stoica BA, Byrnes KR, Jeong W, Faden AI. Activation of mGluR5 and inhibition of NADPH oxidase improves functional recovery after traumatic brain injury. J Neurotrauma 2013. [PMID: 23199080 DOI: 10.1089/neu.2012.2589] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Abstract Traumatic brain injury (TBI) induces microglial activation, which can contribute to secondary tissue loss. Activation of mGluR5 reduces microglial activation and inhibits microglial-mediated neurodegeneration in vitro, and is neuroprotective in experimental models of CNS injury. In vitro studies also suggest that the beneficial effects of mGluR5 activation involve nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibition in activated microglia. We hypothesized that activation of mGluR5 by the selective agonist CHPG after TBI in mice is neuroprotective and that its therapeutic actions are mediated by NADPH oxidase inhibition. Vehicle, CHPG, or CHPG plus the mGluR5 antagonist (MPEP), were administered centrally, 30 minutes post-TBI, and functional recovery and lesion volume was assessed. CHPG significantly attenuated post-traumatic sensorimotor and cognitive deficits, and reduced lesion volumes; these effects were blocked by MPEP, thereby indicating neuroprotection involved selective activation of mGluR5. CHPG treatment also reduced NFκB activity and nitrite production in lipopolysaccharide-stimulated microglia and the protective effects of CHPG treatment were abrogated in NADPH oxidase deficient microglial cultures (gp91(phox-/-)). To address whether the neuroprotective effects of CHPG are mediated via the inhibition of NADPH oxidase, we administered the NADPH oxidase inhibitor apocynin with or without CHPG treatment after TBI. Both apocynin or CHPG treatment alone improved sensorimotor deficits and reduced lesion volumes when compared with vehicle-treated mice; however, the combined CHPG + apocynin treatment was not superior to CHPG alone. These data suggest that the neuroprotective effects of activating mGluR5 receptors after TBI are mediated, in part, via the inhibition of NADPH oxidase.
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Affiliation(s)
- David J Loane
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), National Study Center for Trauma and EMS, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Piao CS, Stoica BA, Wu J, Sabirzhanov B, Zhao Z, Cabatbat R, Loane DJ, Faden AI. Late exercise reduces neuroinflammation and cognitive dysfunction after traumatic brain injury. Neurobiol Dis 2013; 54:252-63. [PMID: 23313314 DOI: 10.1016/j.nbd.2012.12.017] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/21/2012] [Accepted: 12/28/2012] [Indexed: 11/29/2022] Open
Abstract
Delayed secondary biochemical and cellular changes after traumatic brain injury continue for months to years, and are associated with chronic neuroinflammation and progressive neurodegeneration. Physical activity can reduce inflammation and facilitate recovery after brain injury. Here, we investigated the time-dependent effects, and underlying mechanisms of post-traumatic exercise initiation on outcome after moderate traumatic brain injury using a well-characterized mouse controlled cortical impact model. Late exercise initiation beginning at 5weeks after trauma, but not early initiation of exercise at 1week, significantly reduced working and retention memory impairment at 3months, and decreased lesion volume compared to non-exercise injury controls. Cognitive recovery was associated with attenuation of classical inflammatory pathways, activation of alternative inflammatory responses and enhancement of neurogenesis. In contrast, early initiation of exercise failed to alter behavioral recovery or lesion size, while increasing the neurotoxic pro-inflammatory responses. These data underscore the critical importance of timing of exercise initiation after trauma and its relation to neuroinflammation, and challenge the widely held view that effective neuroprotection requires early intervention.
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Affiliation(s)
- Chun-Shu Piao
- Center for Shock, Trauma and Anesthesiology Research (STAR) and Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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