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Eugenín J, Beltrán-Castillo S, Irribarra E, Pulgar-Sepúlveda R, Abarca N, von Bernhardi R. Microglial reactivity in brainstem chemosensory nuclei in response to hypercapnia. Front Physiol 2024; 15:1332355. [PMID: 38476146 PMCID: PMC10927973 DOI: 10.3389/fphys.2024.1332355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 02/08/2024] [Indexed: 03/14/2024] Open
Abstract
Microglia, the resident immune cells of the CNS, surveil, detect, and respond to various extracellular signals. Depending on the nature of these signals, an integrative microglial response can be triggered, resulting in a phenotypic transformation. Here, we evaluate whether hypercapnia modifies microglia phenotype in brainstem respiratory-related nuclei. Adult C57BL/6 inbred mice were exposed to 10% CO2 enriched air (hypercapnia), or pure air (control), for 10 or 30 min and immediately processed for immunohistochemistry to detect the ubiquitous microglia marker, ionized calcium binding adaptor molecule 1 (Iba1). Hypercapnia for thirty, but not 10 min reduced the Iba1 labeling percent coverage in the ventral respiratory column (VRC), raphe nucleus (RN), and nucleus tractus solitarius (NTS) and the number of primary branches in VRC. The morphological changes persisted, at least, for 60 min breathing air after the hypercapnic challenge. No significant changes were observed in Iba1+ cells in the spinal trigeminal nucleus (Sp5) and the hippocampus. In CF-1 outbred mice, 10% CO2 followed by 60 min of breathing air, resulted in the reduction of Iba1 labeling percent coverage and the number and length of primary branches in VRC, RN, and NTS. No morphological change was observed in Iba1+ cells in Sp5 and hippocampus. Double immunofluorescence revealed that prolonged hypercapnia increased the expression of CD86, an inflammatory marker for reactive state microglia, in Iba1+ cells in VRC, RN, and NTS, but not in Sp5 and hippocampus in CF-1 mice. By contrast, the expression of CD206, a marker of regulatory state microglia, persisted unmodified. In brainstem, but not in hippocampal microglia cultures, hypercapnia increased the level of IL1β, but not that of TGFβ measured by ELISA. Our results show that microglia from respiratory-related chemosensory nuclei, are reactive to prolonged hypercapnia acquiring an inflammatory-like phenotype.
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Affiliation(s)
- Jaime Eugenín
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Sebastián Beltrán-Castillo
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
- Centro Integrativo de Biología y Química Aplicada (CIBQA), Universidad Bernardo O’Higgins, Santiago, Chile
| | - Estefanía Irribarra
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | | | - Nicolás Abarca
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Rommy von Bernhardi
- Facultad de Odontología y Ciencias de la Rehabilitación, Universidad San Sebastián, Santiago, Chile
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Vicente MC, Paneghini JL, Stabile AM, Amorim M, Anibal Silva CE, Patrone LGA, Cunha TM, Bícego KC, Almeida MC, Carrettiero DC, Gargaglioni LH. Inhibition of Pro-Inflammatory Microglia with Minocycline Improves Cognitive and Sleep-Wake Dysfunction Under Respiratory Stress in a Sporadic Model for Alzheimer's Disease. J Alzheimers Dis 2023; 95:317-337. [PMID: 37522205 DOI: 10.3233/jad-230151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
BACKGROUND Neuroinflammation in Alzheimer's disease (AD) can occur due to excessive activation of microglia in response to the accumulation of amyloid-β peptide (Aβ). Previously, we demonstrated an increased expression of this peptide in the locus coeruleus (LC) in a sporadic model for AD (streptozotocin, STZ; 2 mg/kg, ICV). We hypothesized that the STZ-AD model exhibits neuroinflammation, and treatment with an inhibitor of microglia (minocycline) can reverse the cognitive, respiratory, sleep, and molecular disorders of this model. OBJECTIVE To evaluate the effect of minocycline treatment in STZ model disorders. METHODS We treated control and STZ-treated rats for five days with minocycline (30 mg/kg, IP) and evaluated cognitive performance, chemoreflex response to hypercapnia and hypoxia, and total sleep time. Additionally, quantification of Aβ, microglia analyses, and relative expression of cytokines in the LC were performed. RESULTS Minocycline treatment improved learning and memory, which was concomitant with a decrease in microglial cell density and re-establishment of morphological changes induced by STZ in the LC region. Minocycline did not reverse the STZ-induced increase in CO2 sensitivity during wakefulness. However, it restored the daytime sleep-wake cycle in STZ-treated animals to the same levels as those observed in control animals. In the LC, levels of A and expression of Il10, Il1b, and Mcp1 mRNA remained unaffected by minocycline, but we found a strong trend of minocycline effect on Tnf- α. CONCLUSION Our findings suggest that minocycline effectively reduces microglial recruitment and the inflammatory morphological profile in the LC, while it recovers cognitive performance and restores the sleep-wake pattern impaired by STZ.
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Affiliation(s)
- Mariane C Vicente
- Department of Animal Morphology and Physiology, Sao Paulo State University - UNESP/FCAV, Jaboticabal, SP, Brazil
- Mary S. Easton Center for Alzheimer's Research and Care, Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Julia L Paneghini
- Department of Animal Morphology and Physiology, Sao Paulo State University - UNESP/FCAV, Jaboticabal, SP, Brazil
| | - Angelita M Stabile
- Department of General and Specialized Nursing, School of Nursing of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Mateus Amorim
- Department of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Conceição E Anibal Silva
- Department of Pharmachology, Medicine School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Luis Gustavo A Patrone
- Department of Animal Morphology and Physiology, Sao Paulo State University - UNESP/FCAV, Jaboticabal, SP, Brazil
| | - Thiago M Cunha
- Department of Pharmachology, Medicine School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Kênia C Bícego
- Department of Animal Morphology and Physiology, Sao Paulo State University - UNESP/FCAV, Jaboticabal, SP, Brazil
| | - Maria C Almeida
- Center for Natural and Human Sciences, Federal University of ABC, São Bernardo do Campo, Brazil
| | - Daniel C Carrettiero
- Center for Natural and Human Sciences, Federal University of ABC, São Bernardo do Campo, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Sao Paulo State University - UNESP/FCAV, Jaboticabal, SP, Brazil
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McMurray KMJ, Sah R. Neuroimmune mechanisms in fear and panic pathophysiology. Front Psychiatry 2022; 13:1015349. [PMID: 36523875 PMCID: PMC9745203 DOI: 10.3389/fpsyt.2022.1015349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/02/2022] [Indexed: 12/02/2022] Open
Abstract
Panic disorder (PD) is unique among anxiety disorders in that the emotional symptoms (e.g., fear and anxiety) associated with panic are strongly linked to body sensations indicative of threats to physiological homeostasis. For example, panic attacks often present with feelings of suffocation that evoke hyperventilation, breathlessness, or air hunger. Due to the somatic underpinnings of PD, a major focus has been placed on interoceptive signaling and it is recognized that dysfunctional body-to-brain communication pathways promote the initiation and maintenance of PD symptomatology. While body-to-brain signaling can occur via several pathways, immune and humoral pathways play an important role in communicating bodily physiological state to the brain. Accumulating evidence suggests that neuroimmune mediators play a role in fear and panic-associated disorders, although this has not been systematically investigated. Currently, our understanding of the role of immune mechanisms in the etiology and maintenance of PD remains limited. In the current review, we attempt to summarize findings that support a role of immune dysregulation in PD symptomology. We compile evidence from human studies and panic-relevant rodent paradigms that indicate a role of systemic and brain immune signaling in the regulation of fear and panic-relevant behavior and physiology. Specifically, we discuss how immune signaling can contribute to maladaptive body-to-brain communication and conditioned fear that are relevant to spontaneous and conditioned symptoms of PD and identify putative avenues warranting future investigation.
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Affiliation(s)
- Katherine M. J. McMurray
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
- Veterans Affairs Medical Center, Cincinnati, OH, United States
| | - Renu Sah
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
- Veterans Affairs Medical Center, Cincinnati, OH, United States
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Winter A, McMurray KMJ, Ahlbrand R, Allgire E, Shukla S, Jones J, Sah R. The subfornical organ regulates acidosis-evoked fear by engaging microglial acid-sensor TDAG8 and forebrain neurocircuits in male mice. J Neurosci Res 2022; 100:1732-1746. [PMID: 35553084 PMCID: PMC9812228 DOI: 10.1002/jnr.25059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 04/06/2022] [Accepted: 04/23/2022] [Indexed: 01/07/2023]
Abstract
An important role of pH homeostasis has been suggested in the physiology of panic disorder, with acidosis as an interoceptive trigger leading to fear and panic. Identification of novel mechanisms that can translate acidosis into fear will promote a better understanding of panic physiology. The current study explores a role of the subfornical organ (SFO), a blood-brain barrier compromised brain area, in translating acidosis to fear-relevant behaviors. We performed SFO-targeted acidification in male, wild-type mice and mice lacking microglial acid-sensing G protein-coupled receptor-T-cell death-associated gene 8 (TDAG8). Localized SFO acidification evoked significant freezing and reduced exploration that was dependent on the presence of acid-sensor TDAG8. Acidosis promoted the activation of SFO microglia and neurons that were absent in TDAG8-deficient mice. The assessment of regional neuronal activation in wild-type and TDAG8-deficient mice following SFO acidification revealed significant acidosis and genotype-dependent alterations in the hypothalamus, amygdala, prefrontal cortex, and periaqueductal gray nuclei. Furthermore, mapping of interregional co-activation patterns revealed that SFO acidosis promoted positive hypothalamic-cortex associations and desynchronized SFO-cortex and amygdala-cortex associations, suggesting an interplay of homeostatic and fear regulatory areas. Importantly, these alterations were not evident in TDAG8-deficient mice. Overall, our data support a regulatory role of subfornical organ microglial acid sensing in acidosis-evoked fear, highlighting a centralized role of blood-brain barrier compromised nodes in interoceptive sensing and behavioral regulation. Identification of pathways by which humoral information can modulate fear behavior is relevant to panic disorder, where aberrant interoceptive signaling has been reported.
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Affiliation(s)
- Andrew Winter
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, Ohio, USA
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio, USA
| | - Katherine M. J. McMurray
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, Ohio, USA
- VA Medical Center, Cincinnati, Ohio, USA
| | - Rebecca Ahlbrand
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, Ohio, USA
- VA Medical Center, Cincinnati, Ohio, USA
| | - Emily Allgire
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, Ohio, USA
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio, USA
| | - Sachi Shukla
- Neuroscience Undergraduate Program, University of Cincinnati, Cincinnati, Ohio, USA
| | - James Jones
- Neuroscience Undergraduate Program, University of Cincinnati, Cincinnati, Ohio, USA
| | - Renu Sah
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, Ohio, USA
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio, USA
- VA Medical Center, Cincinnati, Ohio, USA
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Hedley KE, Callister RJ, Callister R, Horvat JC, Tadros MA. Alterations in brainstem respiratory centers following peripheral inflammation: A systematic review. J Neuroimmunol 2022; 369:577903. [DOI: 10.1016/j.jneuroim.2022.577903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/02/2022] [Accepted: 05/29/2022] [Indexed: 11/29/2022]
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Subfornical organ interleukin 1 receptor: A novel regulator of spontaneous and conditioned fear associated behaviors in mice. Brain Behav Immun 2022; 101:304-317. [PMID: 35032573 PMCID: PMC9836229 DOI: 10.1016/j.bbi.2022.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/25/2021] [Accepted: 01/07/2022] [Indexed: 01/14/2023] Open
Abstract
Impaired threat responding and fear regulation is a hallmark of psychiatric conditions such as post-traumatic stress disorder (PTSD) and Panic Disorder (PD). Most studies have focused on external psychogenic threats to study fear, however, accumulating evidence suggests a primary role of homeostatic perturbations and interoception in regulating emotional behaviors. Heightened reactivity to interoceptive threat carbon dioxide (CO2) inhalation associates with increased risk for developing PD and PTSD, however, contributory mechanisms and molecular targets are not well understood. Previous studies from our group suggested a potential role of interleukin 1 receptor (IL-1R1) signaling within BBB-devoid sensory circumventricular organ, the subfornical organ (SFO) in CO2-evoked fear. However, the necessity of SFO-IL-1R1 in regulating CO2-associated spontaneous fear as well as, long-term fear potentiation relevant to PD/PTSD has not been investigated. The current study tested male mice with SFO-targeted microinfusion of the IL-1R1 antagonist (IL-1RA) or vehicle in a recently developed CO2-startle-fear conditioning-extinction paradigm. Consistent with our hypothesis, SFO IL-1RA treatment elicited significant attenuation of freezing and increased rearing during CO2 inhalation suggesting SFO-IL1R1 regulation of spontaneous fear to CO2. Intriguingly, SFO IL-1RA treatment normalized CO2-associated potentiation of conditioned fear and impaired extinction a week later suggesting modulation of long-term fear by SFO-IL-1R1 signaling. Post behavior FosB mapping revealed recruitment of prefrontal cortex-amygdala-periaqueductal gray (PAG) areas in SFO-IL-1RA mediated effects. Additionally, we localized cellular IL-1R1 expression within the SFO to blood vessel endothelial cells and observed CO2-induced alterations in IL-1β/IL-1R1 expression in peripheral mononuclear cells and SFO. Lastly, CO2-evoked microglial activation was attenuated in SFO-IL-1RA treated mice. These observations suggest a peripheral monocyte-endothelial-microglia interplay in SFO-IL-1R1 modulation of CO2-associated spontaneous fear and delayed fear memory. Collectively, our data highlight a novel, "bottom-up" neuroimmune mechanism that integrates interoceptive and exteroceptive threat processing of relevance to fear-related pathologies.
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