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Cleaver J, Jeffery K, Klenerman P, Lim M, Handunnetthi L, Irani SR, Handel A. The immunobiology of herpes simplex virus encephalitis and post-viral autoimmunity. Brain 2024; 147:1130-1148. [PMID: 38092513 PMCID: PMC10994539 DOI: 10.1093/brain/awad419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/25/2023] [Accepted: 11/27/2023] [Indexed: 04/06/2024] Open
Abstract
Herpes simplex virus encephalitis (HSE) is the leading cause of non-epidemic encephalitis in the developed world and, despite antiviral therapy, mortality and morbidity is high. The emergence of post-HSE autoimmune encephalitis reveals a new immunological paradigm in autoantibody-mediated disease. A reductionist evaluation of the immunobiological mechanisms in HSE is crucial to dissect the origins of post-viral autoimmunity and supply rational approaches to the selection of immunotherapeutics. Herein, we review the latest evidence behind the phenotypic progression and underlying immunobiology of HSE including the cytokine/chemokine environment, the role of pathogen-recognition receptors, T- and B-cell immunity and relevant inborn errors of immunity. Second, we provide a contemporary review of published patients with post-HSE autoimmune encephalitis from a combined cohort of 110 patients. Third, we integrate novel mechanisms of autoimmunization in deep cervical lymph nodes to explore hypotheses around post-HSE autoimmune encephalitis and challenge these against mechanisms of molecular mimicry and others. Finally, we explore translational concepts where neuroglial surface autoantibodies have been observed with other neuroinfectious diseases and those that generate brain damage including traumatic brain injury, ischaemic stroke and neurodegenerative disease. Overall, the clinical and immunological landscape of HSE is an important and evolving field, from which precision immunotherapeutics could soon emerge.
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Affiliation(s)
- Jonathan Cleaver
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Department of Neurology, John Radcliffe Hospital, Oxford University Hospitals, Oxford, OX3 9DU, UK
| | - Katie Jeffery
- Department of Microbiology, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 9DU, UK
- Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Paul Klenerman
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
- Translational Gastroenterology Unit, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Ming Lim
- Children’s Neurosciences, Evelina London Children’s Hospital at Guy’s and St Thomas’ NHS Foundation Trust, London, SE1 7EH, UK
- Department Women and Children’s Health, School of Life Course Sciences, King’s College London, London, WC2R 2LS, UK
| | - Lahiru Handunnetthi
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Sarosh R Irani
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Department of Neurology, John Radcliffe Hospital, Oxford University Hospitals, Oxford, OX3 9DU, UK
| | - Adam Handel
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Department of Neurology, John Radcliffe Hospital, Oxford University Hospitals, Oxford, OX3 9DU, UK
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Fritsch LE, Kelly C, Leonard J, de Jager C, Wei X, Brindley S, Harris EA, Kaloss AM, DeFoor N, Paul S, O'Malley H, Ju J, Olsen ML, Theus MH, Pickrell AM. STING-Dependent Signaling in Microglia or Peripheral Immune Cells Orchestrates the Early Inflammatory Response and Influences Brain Injury Outcome. J Neurosci 2024; 44:e0191232024. [PMID: 38360749 PMCID: PMC10957216 DOI: 10.1523/jneurosci.0191-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 12/16/2023] [Accepted: 01/02/2024] [Indexed: 02/17/2024] Open
Abstract
While originally identified as an antiviral pathway, recent work has implicated that cyclic GMP-AMP-synthase-Stimulator of Interferon Genes (cGAS-STING) signaling is playing a critical role in the neuroinflammatory response to traumatic brain injury (TBI). STING activation results in a robust inflammatory response characterized by the production of inflammatory cytokines called interferons, as well as hundreds of interferon stimulated genes (ISGs). Global knock-out (KO) mice inhibiting this pathway display neuroprotection with evidence that this pathway is active days after injury; yet, the early neuroinflammatory events stimulated by STING signaling remain understudied. Furthermore, the source of STING signaling during brain injury is unknown. Using a murine controlled cortical impact (CCI) model of TBI, we investigated the peripheral immune and microglial response to injury utilizing male chimeric and conditional STING KO animals, respectively. We demonstrate that peripheral and microglial STING signaling contribute to negative outcomes in cortical lesion volume, cell death, and functional outcomes postinjury. A reduction in overall peripheral immune cell and neutrophil infiltration at the injury site is STING dependent in these models at 24 h. Transcriptomic analysis at 2 h, when STING is active, reveals that microglia drive an early, distinct transcriptional program to elicit proinflammatory genes including interleukin 1-β (IL-1β), which is lost in conditional knock-out mice. The upregulation of alternative innate immune pathways also occurs after injury in these animals, which supports a complex relationship between brain-resident and peripheral immune cells to coordinate the proinflammatory response and immune cell influx to damaged tissue after injury.
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Affiliation(s)
- Lauren E Fritsch
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia 24016
| | - Colin Kelly
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia 24016
| | - John Leonard
- Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Caroline de Jager
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia 24016
| | - Xiaoran Wei
- Biomedical and Veterinary Sciences Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Samantha Brindley
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Elizabeth A Harris
- Biomedical and Veterinary Sciences Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Alexandra M Kaloss
- Biomedical and Veterinary Sciences Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Nicole DeFoor
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Swagatika Paul
- Biomedical and Veterinary Sciences Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Hannah O'Malley
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Jing Ju
- Biomedical and Veterinary Sciences Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Michelle L Olsen
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Michelle H Theus
- Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Alicia M Pickrell
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
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Chakrabarti S, Gorai S, Pahan K. A simple protocol for isolating microglia from adult mouse brain. NEUROIMMUNE PHARMACOLOGY AND THERAPEUTICS 2023; 2:293-300. [PMID: 37885917 PMCID: PMC10474378 DOI: 10.1515/nipt-2023-0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 07/20/2023] [Indexed: 10/28/2023]
Abstract
Objectives Although microglia are activated in adult and aged brains resulting in neurodegenerative and neuroinflammatory disorders, most of the cell culture studies on microglia deal with neonatal microglia because of ease of isolation. Microglia could be isolated from adult brains, but it requires separation by density gradient centrifugation, magnetic beads, etc. Here, we describe a simple protocol of isolating highly purified microglia from adult mouse brains. Methods Our protocol involves dilution with sterile PBS or media, regular centrifugation, and plating on poly-D-lysine-coated flasks. Results These adult microglia expressed the inducible nitric oxide synthase in response to preformed α-syn fibril, an etiological reagent of Parkinson's disease, and bacterial lipopolysaccharides, one of the prototype proinflammatory stimuli. Moreover, these adult microglia exhibited phagocytosis, which was stimulated by LPS treatment. Conclusions These results suggest that adult microglia isolated by our procedure are functional and that these adult microglia could be used for studies related to neurodegenerative disorders.
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Affiliation(s)
- Sudipta Chakrabarti
- Department of Neurological Sciences, Rush University Medical Center, Chicago, USA
| | - Sukhamoy Gorai
- Department of Neurological Sciences, Rush University Medical Center, Chicago, USA
| | - Kalipada Pahan
- Department of Neurological Sciences, Rush University Medical Center, Chicago, USA
- Division of Research and Development, Jesse Brown Veterans Affairs Medical Center, Chicago, USA
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Fruhwürth S, Reinert LS, Öberg C, Sakr M, Henricsson M, Zetterberg H, Paludan SR. TREM2 is down-regulated by HSV1 in microglia and involved in antiviral defense in the brain. SCIENCE ADVANCES 2023; 9:eadf5808. [PMID: 37595041 PMCID: PMC10438464 DOI: 10.1126/sciadv.adf5808] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 07/19/2023] [Indexed: 08/20/2023]
Abstract
Immunological control of viral infections in the brain exerts immediate protection and also long-term maintenance of brain integrity. Microglia are important for antiviral defense in the brain. Here, we report that herpes simplex virus type 1 (HSV1) infection of human induced pluripotent stem cell (hiPSC)-derived microglia down-regulates expression of genes in the TREM2 pathway. TREM2 was found to be important for virus-induced IFNB induction through the DNA-sensing cGAS-STING pathway in microglia and for phagocytosis of HSV1-infected neurons. Consequently, TREM2 depletion increased susceptibility to HSV1 infection in human microglia-neuron cocultures and in the mouse brain. TREM2 augmented STING signaling and activation of downstream targets TBK1 and IRF3. Thus, TREM2 is important for the antiviral immune response in microglia. Since TREM2 loss-of-function mutations and HSV1 serological status are both linked to Alzheimer's disease, this work poses the question whether genetic or virus-induced alterations of TREM2 activity predispose to post-infection neurological pathologies.
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Affiliation(s)
- Stefanie Fruhwürth
- Department of Rheumatology and Inflammatory Research, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Line S. Reinert
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Carl Öberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Marcelina Sakr
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Marcus Henricsson
- Biomarker Discovery and Development, Research and Early Development, Cardiovascular, Renal, and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK
- UK Dementia Research Institute at UCL, London, UK
- Hong Kong Center for Neurodegenerative Diseases, Clear Water Bay, Hong Kong, China
| | - Søren R. Paludan
- Department of Rheumatology and Inflammatory Research, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Nunes JM, Kell DB, Pretorius E. Cardiovascular and haematological pathology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): A role for viruses. Blood Rev 2023; 60:101075. [PMID: 36963989 PMCID: PMC10027292 DOI: 10.1016/j.blre.2023.101075] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 03/25/2023]
Abstract
ME/CFS is a debilitating chronic condition that often develops after viral or bacterial infection. Insight from the study of Long COVID/Post Acute Sequelae of COVID-19 (PASC), the post-viral syndrome associated with SARS-CoV-2 infection, might prove to be useful for understanding pathophysiological mechanisms of ME/CFS. Disease presentation is similar between the two conditions, and a subset of Long COVID patients meet the diagnostic criteria for ME/CFS. Since Long COVID is characterized by significant vascular pathology - including endothelial dysfunction, coagulopathy, and vascular dysregulation - the question of whether or not the same biological abnormalities are of significance in ME/CFS arises. Cardiac abnormalities have for a while now been documented in ME/CFS cohorts, with recent studies demonstrating major deficits in cerebral blood flow, and hence vascular dysregulation. A growing body of research is demonstrating that ME/CFS is accompanied by platelet hyperactivation, anomalous clotting, a procoagulant phenotype, and endothelial dysfunction. Endothelial damage and dysregulated clotting can impair substance exchange between blood and tissues, and result in hypoperfusion, which may contribute to the manifestation of certain ME/CFS symptoms. Here we review the ME/CFS literature to summarize cardiovascular and haematological findings documented in patients with the condition, and, in this context, briefly discuss the potential role of previously-implicated pathogens. Overall, cardiac and haematological abnormalities are present within ME/CFS cohorts. While atherosclerotic heart disease is not significantly associated with ME/CFS, suboptimal cardiovascular function defined by reduced cardiac output, impaired cerebral blood flow, and vascular dysregulation are, and these abnormalities do not appear to be influenced by deconditioning. Rather, these cardiac abnormalities may result from dysfunction in the (autonomic) nervous system. Plenty of recently published studies are demonstrating significant platelet hyperactivity and endothelial dysfunction in ME/CFS, as well as anomalous clotting processes. It is of particular importance to determine to what extent these cardiovascular and haematological abnormalities contribute to symptom severity, and if these two systems can be targeted for therapeutic purposes. Viral reservoirs of herpesviruses exist in ME/CFS, and most likely contribute to cardiovascular and haematological dysfunction directly or indirectly. This review highlights the potential of studying cardiac functioning, the vasculature, and coagulation system in ME/CFS.
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Affiliation(s)
- Jean M Nunes
- Department of Physiological Sciences, Faculty of Science, Stellenbosch University, Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
| | - Douglas B Kell
- Department of Physiological Sciences, Faculty of Science, Stellenbosch University, Stellenbosch, Private Bag X1, Matieland 7602, South Africa; Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK; The Novo Nordisk Foundation Centre for Biosustainability, Building 220, Chemitorvet 200, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
| | - Etheresia Pretorius
- Department of Physiological Sciences, Faculty of Science, Stellenbosch University, Stellenbosch, Private Bag X1, Matieland 7602, South Africa; Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK.
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Arutyunov A, Klein RS. Microglia at the scene of the crime: what their transcriptomics reveal about brain health. Curr Opin Neurol 2023; 36:207-213. [PMID: 37078646 PMCID: PMC10867866 DOI: 10.1097/wco.0000000000001151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
PURPOSE OF REVIEW Microglia, which arise from primitive myeloid precursors that enter the central nervous system (CNS) during early development, are the first responders to any perturbance of homeostasis. Although their activation has become synonymous with neurologic disease, it remains unclear whether microglial responses are the cause of or response to neuropathology. Here, we review new insights in the roles of microglia during CNS health and disease, including preclinical studies that transcriptionally profile microglia to define their functional states. RECENT FINDINGS Converging evidence suggests that innate immune activation of microglia is associated with overlapping alterations in their gene expression profiles regardless of the trigger. Thus, recent studies examining neuroprotective microglial responses during infections and aging mirror those observed during chronic neurologic diseases, including neurodegeneration and stroke. Many of these insights derive from studies of microglial transcriptomes and function in preclinical models, some of which have been validated in human samples. During immune activation, microglia dismantle their homeostatic functions and transition into subsets capable of antigen presentation, phagocytosis of debris, and management of lipid homeostasis. These subsets can be identified during both normal and aberrant microglial responses, the latter of which may persist long-term. The loss of neuroprotective microglia, which maintain a variety of essential CNS functions, may therefore, in part, underlie the development of neurodegenerative diseases. SUMMARY Microglia exhibit a high level of plasticity, transforming into numerous subsets as they respond to innate immune triggers. Chronic loss of microglial homeostatic functions may underlie the development of diseases with pathological forgetting.
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Affiliation(s)
- Artem Arutyunov
- Center for Neuroimmunology & Neuroinfectious Diseases
- Departments of Medicine
| | - Robyn S. Klein
- Center for Neuroimmunology & Neuroinfectious Diseases
- Departments of Medicine
- Departments of Pathology & Immunology
- Departments of Neurosciences
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McMillan RE, Wang E, Carlin AF, Coufal NG. Human microglial models to study host-virus interactions. Exp Neurol 2023; 363:114375. [PMID: 36907350 PMCID: PMC10521930 DOI: 10.1016/j.expneurol.2023.114375] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 02/13/2023] [Accepted: 03/02/2023] [Indexed: 03/14/2023]
Abstract
Microglia, the resident macrophage of the central nervous system, are increasingly recognized as contributing to diverse aspects of human development, health, and disease. In recent years, numerous studies in both mouse and human models have identified microglia as a "double edged sword" in the progression of neurotropic viral infections: protecting against viral replication and cell death in some contexts, while acting as viral reservoirs and promoting excess cellular stress and cytotoxicity in others. It is imperative to understand the diversity of human microglial responses in order to therapeutically modulate them; however, modeling human microglia has been historically challenging due to significant interspecies differences in innate immunity and rapid transformation upon in vitro culture. In this review, we discuss the contribution of microglia to the neuropathogenesis of key neurotropic viral infections: human immunodeficiency virus 1 (HIV-1), Zika virus (ZIKV), Japanese encephalitis virus (JEV), West Nile virus (WNV), Herpes simplex virus (HSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We pay special attention to recent work with human stem cell-derived microglia and propose strategies to leverage these powerful models to further uncover species- and disease-specific microglial responses and novel therapeutic interventions for neurotropic viral infections.
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Affiliation(s)
- Rachel E McMillan
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, United States of America; Department of Pathology and Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093, United States of America
| | - Ellen Wang
- Department of Pediatrics, University of California, San Diego, School of Medicine, La Jolla, CA 92093, United States of America; Sanford Consortium for Regenerative Medicine, La Jolla, CA 92093, United States of America
| | - Aaron F Carlin
- Department of Pathology and Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093, United States of America.
| | - Nicole G Coufal
- Department of Pediatrics, University of California, San Diego, School of Medicine, La Jolla, CA 92093, United States of America; Sanford Consortium for Regenerative Medicine, La Jolla, CA 92093, United States of America.
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Fritsch LE, Kelly C, Pickrell AM. The role of STING signaling in central nervous system infection and neuroinflammatory disease. WIREs Mech Dis 2023; 15:e1597. [PMID: 36632700 PMCID: PMC10175194 DOI: 10.1002/wsbm.1597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/27/2022] [Accepted: 12/21/2022] [Indexed: 01/13/2023]
Abstract
The cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthase-Stimulator of Interferon Genes (cGAS-STING) pathway is a critical innate immune mechanism for detecting the presence of double-stranded DNA (dsDNA) and prompting a robust immune response. Canonical cGAS-STING activation occurs when cGAS, a predominantly cytosolic pattern recognition receptor, binds microbial DNA to promote STING activation. Upon STING activation, transcription factors enter the nucleus to cause the production of Type I interferons, inflammatory cytokines whose primary function is to prime the host for viral infection by producing a number of antiviral interferon-stimulated genes. While the pathway was originally described in viral infection, more recent studies have implicated cGAS-STING signaling in a number of different contexts, including autoimmune disease, cancer, injury, and neuroinflammatory disease. This review focuses on how our understanding of the cGAS-STING pathway has evolved over time with an emphasis on the role of STING-mediated neuroinflammation and infection in the nervous system. We discuss recent findings on how STING signaling contributes to the pathology of pain, traumatic brain injury, and stroke, as well as how mitochondrial DNA may promote STING activation in common neurodegenerative diseases. We conclude by commenting on the current knowledge gaps that should be filled before STING can be an effective therapeutic target in neuroinflammatory disease. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology Infectious Diseases > Molecular and Cellular Physiology Immune System Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Lauren E. Fritsch
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia, USA
| | - Colin Kelly
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, Virginia, USA
| | - Alicia M. Pickrell
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
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West PK, Viengkhou B, Campbell IL, Hofer MJ. Microglia shield the murine brain from damage mediated by the cytokines IL-6 and IFN-α. Front Immunol 2022; 13:1036799. [PMID: 36389783 PMCID: PMC9650248 DOI: 10.3389/fimmu.2022.1036799] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 10/13/2022] [Indexed: 12/10/2023] Open
Abstract
Sustained production of elevated levels of the cytokines interleukin (IL)-6 or interferon (IFN)-α in the central nervous system (CNS) is detrimental and directly contributes to the pathogenesis of neurological diseases such as neuromyelitis optica spectrum disorders or cerebral interferonopathies, respectively. Using transgenic mice with CNS-targeted production of IL-6 (GFAP-IL6) or IFN-α (GFAP-IFN), we have recently demonstrated that microglia are prominent target and effector cells and mount stimulus-specific responses to these cytokines. In order to further clarify the phenotype and function of these cells, we treated GFAP-IL6 and GFAP-IFN mice with the CSF1R inhibitor PLX5622 to deplete microglia. We examined their ability to recover from acute microglia depletion, as well as the impact of chronic microglia depletion on the progression of disease. Following acute depletion in the brains of GFAP-IL6 mice, microglia repopulation was enhanced, while in GFAP-IFN mice, microglia did not repopulate the brain. Furthermore, chronic CSF1R inhibition was detrimental to the brain of GFAP-IL6 and GFAP-IFN mice and gave rise to severe CNS calcification which strongly correlated with the absence of microglia. In addition, PLX5622-treated GFAP-IFN mice had markedly reduced survival. Our findings provide evidence for novel microglia functions to protect against IFN-α-mediated neurotoxicity and neuronal dysregulation, as well as restrain calcification as a result of both IL-6- and IFN-α-induced neuroinflammation. Taken together, we demonstrate that CSF1R inhibition may be an undesirable target for therapeutic treatment of neuroinflammatory diseases that are driven by elevated IL-6 and IFN-α production.
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Affiliation(s)
| | | | | | - Markus J. Hofer
- School of Life and Environmental Sciences, Charles Perkins Centre and the Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW, Australia
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