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Zhou W, He J, Shen G, Liu Y, Zhao P, Li J. TREM2-dependent activation of microglial cell protects photoreceptor cell during retinal degeneration via PPARγ and CD36. Cell Death Dis 2024; 15:623. [PMID: 39187498 PMCID: PMC11347571 DOI: 10.1038/s41419-024-07002-z] [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: 03/29/2024] [Revised: 08/09/2024] [Accepted: 08/13/2024] [Indexed: 08/28/2024]
Abstract
Retinal degeneration is a collection of devastating conditions with progressive loss of vision which often lead to blindness. Research on retinal microglial cells offers great therapeutic potential in deterring the progression of degeneration. This study explored the mechanisms underlying the TREM2-mediated protective function of activated microglial cells during retinal degeneration. N-methyl-N-nitrosourea (MNU)-induced retinal degeneration was established in C57BL/6 J (WT) and Trem2 knockout (Trem2-/-) mice. We discovered that MNU treatment led to the concurrent processes of photoreceptor apoptosis and microglia infiltration. A significant upregulation of disease-associated microglia signature genes was observed during photoreceptor degeneration. Following MNU treatment, Trem2-/- mice showed exacerbated photoreceptor cell death, decreased microglia migration and phagocytosis, reduced microglial PPARγ activation and CD36 expression. Pharmaceutical activation of PPARγ promoted microglial migration, ameliorated photoreceptor degeneration and restored CD36 expression in MNU-treated Trem2-/- mice. Inhibition of CD36 activity worsened photoreceptor degeneration in MNU-treated WT mice. Our findings suggested that the protective effect of microglia during retinal degeneration was dependent on Trem2 expression and carried out via the activation of PPARγ and the consequent upregulation of CD36 expression. Our study linked TREM2 signaling with PPARγ activation, and provided a potential therapeutic target for the management of retinal degeneration.
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Affiliation(s)
- Wenchuan Zhou
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Jincan He
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Guiyan Shen
- Institute of Traditional Chinese Medicine and Stem Cell Research, College of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Ya Liu
- Institute of Traditional Chinese Medicine and Stem Cell Research, College of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Peiquan Zhao
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
| | - Jing Li
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
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Suryadi T, Kulsum K. Comparison between premortem histopathology findings in rats with and without traumatic brain injury: prospective application in forensic medicine. F1000Res 2024; 12:1311. [PMID: 39282512 PMCID: PMC11399755 DOI: 10.12688/f1000research.140718.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/14/2024] [Indexed: 09/19/2024] Open
Abstract
Background The aim of this study was to compare pre-mortem histopathology findings in rats with and without traumatic brain injury (TBI) and its prospective application in forensic medicine. Methods This study involved 12 rats with 6 rats for each treatment group. This type of study is a laboratory experimental study with two independent groups design. The first group were rats that did not experience TBI. The second group was a group of rats with TBI. The subjects of this study were Rattus norvegicus rats, adult males, 4-8 weeks old, weighing 150-200 grams. On the 8 th day after the rats experienced traumatic brain injury, the rats were then euthanized using the cervical dislocation method, after euthanasia the rats were given craniotomy and brain tissue was taken for histopathology examination. Results The description of histopathology changes in the brain organs in the group of rat without TBI found that neuron cells looked normal although there were also degeneration (21.16 ± 2.56/FV), necrosis (5.75 ± 0.98/FV), apoptosis (2.91 ± 0.80/FV), congestion ( 0.91 ± 0.49/FV), inflammatory cells (4.58 ± 1.15/FV) and hemorrhage (2.41 ± 1.11/FV). Changes in the rat traumatic brain injury group showed a lot of damage to neuron cells in the form of degeneration (48.41 ± 3.27/FV), necrosis (36.66 ± 2.89/FV), apoptosis (18.91 ± 1.24/FV), congestion (2.50 ±0.31/FV), inflammatory cells (11.41 ± 1.71/FV) and hemorrhage (10.08 ± 2.17/FV). Based on the results of statistical analysis, it can be seen that in all parameters there is a significant difference (p ≤ 0.001). Conclusions The premortem histopathology findings in rats with and without TBI which can be used for the benefit of forensic medicine in determining whether TBI is present or not. It is necessary to look more closely at the histopathology changes in the form of necrosis, apoptosis and hemorrhage.
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Affiliation(s)
- Taufik Suryadi
- Department of Forensic Medicine and Medicolegal, Dr. Zainoel Abidin Hospital, Banda Aceh, Aceh, 23126, Indonesia
- Department of Forensic Medicine and Medicolegal, Faculty of Medicine, Syiah Kuala University, Banda Aceh, Aceh, 23111, Indonesia
| | - Kulsum Kulsum
- Department of Anesthesiology and Intensive Therapy, Dr. Zainoel Abidin Hospital, Banda Aceh, Aceh, 23126, Indonesia
- Department of Anesthesiology and Intensive Therapy, Faculty of Medicine, Syiah Kuala University, Banda Aceh, Aceh, 23111, Indonesia
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Chitu V, Biundo F, Stanley ER. Colony stimulating factors in the nervous system. Semin Immunol 2021; 54:101511. [PMID: 34743926 DOI: 10.1016/j.smim.2021.101511] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/23/2021] [Indexed: 01/02/2023]
Abstract
Although traditionally seen as regulators of hematopoiesis, colony-stimulating factors (CSFs) have emerged as important players in the nervous system, both in health and disease. This review summarizes the cellular sources, patterns of expression and physiological roles of the macrophage (CSF-1, IL-34), granulocyte-macrophage (GM-CSF) and granulocyte (G-CSF) colony stimulating factors within the nervous system, with a particular focus on their actions on microglia. CSF-1 and IL-34, via the CSF-1R, are required for the development, proliferation and maintenance of essentially all CNS microglia in a temporal and regional specific manner. In contrast, in steady state, GM-CSF and G-CSF are mainly involved in regulation of microglial function. The alterations in expression of these growth factors and their receptors, that have been reported in several neurological diseases, are described and the outcomes of their therapeutic targeting in mouse models and humans are discussed.
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Affiliation(s)
- Violeta Chitu
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Fabrizio Biundo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - E Richard Stanley
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Carroll JA, Race B, Williams K, Striebel JF, Chesebro B. Innate immune responses after stimulation with Toll-like receptor agonists in ex vivo microglial cultures and an in vivo model using mice with reduced microglia. J Neuroinflammation 2021; 18:194. [PMID: 34488805 PMCID: PMC8419892 DOI: 10.1186/s12974-021-02240-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 08/14/2021] [Indexed: 12/02/2022] Open
Abstract
Background Past experiments studying innate immunity in the central nervous system (CNS) utilized microglia obtained from neonatal mouse brain, which differ developmentally from adult microglia. These differences might impact our current understanding of the role of microglia in CNS development, function, and disease. Methods Cytokine protein secretion was compared in ex vivo P3 and adult microglial cultures after exposure to agonists for three different toll-like receptors (TLR4, lipopolysaccharide [LPS]; TLR7, imiquimod [IMQ]; and TLR9, CpG Oligodeoxynucleotide [CpG-ODN] 1585). In addition, changes in inflammatory gene expression in ex vivo adult microglia in response to the TLR agonists was assessed. Furthermore, in vivo experiments evaluated changes in gene expression associated with inflammation and TLR signaling in brains of mice with or without treatment with PLX5622 to reduce microglia. Results Ex vivo adult and P3 microglia increased cytokine secretion when exposed to TLR4 agonist LPS and to TLR7 agonist IMQ. However, adult microglia decreased expression of numerous genes after exposure to TLR 9 agonist CpG-ODN 1585. In contrast, in vivo studies indicated a core group of inflammatory and TLR signaling genes increased when each of the TLR agonists was introduced into the CNS. Reducing microglia in the brain led to decreased expression of various inflammatory and TLR signaling genes. Mice with reduced microglia showed extreme impairment in upregulation of genes after exposure to TLR7 agonist IMQ. Conclusions Cultured adult microglia were more reactive than P3 microglia to LPS or IMQ exposure. In vivo results indicated microglial influences on neuroinflammation were agonist specific, with responses to TLR7 agonist IMQ more dysregulated in mice with reduced microglia. Thus, TLR7-mediated innate immune responses in the CNS appeared more dependent on the presence of microglia. Furthermore, partial responses to TLR4 and TLR9 agonists in mice with reduced microglia suggested other cell types in the CNS can compensate for their absence. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02240-w.
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Affiliation(s)
- James A Carroll
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South Fourth Street, Hamilton, MT, 59840, USA.
| | - Brent Race
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South Fourth Street, Hamilton, MT, 59840, USA
| | - Katie Williams
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South Fourth Street, Hamilton, MT, 59840, USA
| | - James F Striebel
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South Fourth Street, Hamilton, MT, 59840, USA
| | - Bruce Chesebro
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South Fourth Street, Hamilton, MT, 59840, USA
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Li Q, Shen C, Liu Z, Ma Y, Wang J, Dong H, Zhang X, Wang Z, Yu M, Ci L, Sun R, Shen R, Fei J, Huang F. Partial depletion and repopulation of microglia have different effects in the acute MPTP mouse model of Parkinson's disease. Cell Prolif 2021; 54:e13094. [PMID: 34312932 PMCID: PMC8349650 DOI: 10.1111/cpr.13094] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/25/2021] [Accepted: 06/26/2021] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVES Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the progressive and selective degeneration of dopaminergic neurons. Microglial activation and neuroinflammation are associated with the pathogenesis of PD. However, the relationship between microglial activation and PD pathology remains to be explored. MATERIALS AND METHODS An acute regimen of MPTP was administered to adult C57BL/6J mice with normal, much reduced or repopulated microglial population. Damages of the dopaminergic system were comprehensively assessed. Inflammation-related factors were assessed by quantitative PCR and Multiplex immunoassay. Behavioural tests were carried out to evaluate the motor deficits in MPTP-challenged mice. RESULTS The receptor for colony-stimulating factor 1 inhibitor PLX3397 could effectively deplete microglia in the nigrostriatal pathway of mice via feeding a PLX3397-formulated diet for 21 days. Microglial depletion downregulated both pro-inflammatory and anti-inflammatory molecule expression at baseline and after MPTP administration. At 1d post-MPTP injection, dopaminergic neurons showed a significant reduction in PLX3397-fed mice, but not in control diet (CD)-fed mice. However, partial microglial depletion in mice exerted little effect on MPTP-induced dopaminergic injuries compared with CD mice at later time points. Interestingly, microglial repopulation brought about apparent resistance to MPTP intoxication. CONCLUSIONS Microglia can inhibit PD development at a very early stage; partial microglial depletion has little effect in terms of the whole process of the disease; and microglial replenishment elicits neuroprotection in PD mice.
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Affiliation(s)
- Qing Li
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China.,Shanghai Engineering Research Center for Model Organisms, Shanghai Model Organisms Center, INC, Shanghai, China
| | - Chenye Shen
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Zhaolin Liu
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yuanyuan Ma
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Jinghui Wang
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Hongtian Dong
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Xiaoshuang Zhang
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Zishan Wang
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Mei Yu
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
| | - Lei Ci
- Shanghai Engineering Research Center for Model Organisms, Shanghai Model Organisms Center, INC, Shanghai, China
| | - Ruilin Sun
- Shanghai Engineering Research Center for Model Organisms, Shanghai Model Organisms Center, INC, Shanghai, China
| | - Ruling Shen
- Joint Laboratory for Technology of Model Organism, Shanghai Laboratory Animal Research Center and School of Life Science and Technology, Tongji University.,Shanghai Laboratory Animal Research Center, Shanghai, China
| | - Jian Fei
- Joint Laboratory for Technology of Model Organism, Shanghai Laboratory Animal Research Center and School of Life Science and Technology, Tongji University.,Shanghai Laboratory Animal Research Center, Shanghai, China.,School of Life Science and Technology, Tongji University, Shanghai, China
| | - Fang Huang
- Department of Translational Neuroscience, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Jing' an District Centre Hospital of Shanghai Institutes of Brain Science, Fudan University, Shanghai, China
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Deletion of Kif5c Does Not Alter Prion Disease Tempo or Spread in Mouse Brain. Viruses 2021; 13:v13071391. [PMID: 34372599 PMCID: PMC8310152 DOI: 10.3390/v13071391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/06/2021] [Accepted: 07/15/2021] [Indexed: 11/16/2022] Open
Abstract
In prion diseases, the spread of infectious prions (PrPSc) is thought to occur within nerves and across synapses of the central nervous system (CNS). However, the mechanisms by which PrPSc moves within axons and across nerve synapses remain undetermined. Molecular motors, including kinesins and dyneins, transport many types of intracellular cargo. Kinesin-1C (KIF5C) has been shown to transport vesicles carrying the normal prion protein (PrPC) within axons, but whether KIF5C is involved in PrPSc axonal transport is unknown. The current study tested whether stereotactic inoculation in the striatum of KIF5C knock-out mice (Kif5c−/−) with 0.5 µL volumes of mouse-adapted scrapie strains 22 L or ME7 would result in an altered rate of prion spreading and/or disease timing. Groups of mice injected with each strain were euthanized at either pre-clinical time points or following the development of prion disease. Immunohistochemistry for PrP was performed on brain sections and PrPSc distribution and tempo of spread were compared between mouse strains. In these experiments, no differences in PrPSc spread, distribution or survival times were observed between C57BL/6 and Kif5c−/− mice.
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Striebel JF, Race B, Leung JM, Schwartz C, Chesebro B. Prion-induced photoreceptor degeneration begins with misfolded prion protein accumulation in cones at two distinct sites: cilia and ribbon synapses. Acta Neuropathol Commun 2021; 9:17. [PMID: 33509294 PMCID: PMC7845122 DOI: 10.1186/s40478-021-01120-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 01/09/2021] [Indexed: 12/15/2022] Open
Abstract
Accumulation of misfolded host proteins is central to neuropathogenesis of numerous human brain diseases including prion and prion-like diseases. Neurons of retina are also affected by these diseases. Previously, our group and others found that prion-induced retinal damage to photoreceptor cells in mice and humans resembled pathology of human retinitis pigmentosa caused by mutations in retinal proteins. Here, using confocal, epifluorescent and electron microscopy we followed deposition of disease-associated prion protein (PrPSc) and its association with damage to critical retinal structures following intracerebral prion inoculation. The earliest time and place of retinal PrPSc deposition was 67 days post-inoculation (dpi) on the inner segment (IS) of cone photoreceptors. At 104 and 118 dpi, PrPSc was associated with the base of cilia and swollen cone inner segments, suggesting ciliopathy as a pathogenic mechanism. By 118 dpi, PrPSc was deposited in both rods and cones which showed rootlet damage in the IS, and photoreceptor cell death was indicated by thinning of the outer nuclear layer. In the outer plexiform layer (OPL) in uninfected mice, normal host PrP (PrPC) was mainly associated with cone bipolar cell processes, but in infected mice, at 118 dpi, PrPSc was detected on cone and rod bipolar cell dendrites extending into ribbon synapses. Loss of ribbon synapses in cone pedicles and rod spherules in the OPL was observed to precede destruction of most rods and cones over the next 2–3 weeks. However, bipolar cells and horizontal cells were less damaged, indicating high selectivity among neurons for injury by prions. PrPSc deposition in cone and rod inner segments and on the bipolar cell processes participating in ribbon synapses appear to be critical early events leading to damage and death of photoreceptors after prion infection. These mechanisms may also occur in human retinitis pigmentosa and prion-like diseases, such as AD.
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Singh N, Chaudhary S, Ashok A, Lindner E. Prions and prion diseases: Insights from the eye. Exp Eye Res 2020; 199:108200. [PMID: 32858007 DOI: 10.1016/j.exer.2020.108200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/24/2020] [Accepted: 08/21/2020] [Indexed: 12/30/2022]
Abstract
Prion diseases are invariably fatal neurodegenerative disorders that have gained much publicity due to their transmissible nature. Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common human prion disorder, with an incidence of 1 in a million. Inherited prion disorders are relatively rare, and associated with mutations in the prion protein gene. More than 50 different point mutations, deletions, and insertions have been identified so far. Most are autosomal dominant and fully penetrant. Prion disorders also occur in animals, and are of major concern because of the potential for spreading to humans. The principal pathogenic event underlying all prion disorders is a change in the conformation of prion protein (PrPC) from a mainly α-helical to a β-sheet rich isoform, PrP-scrapie (PrPSc). Accumulation of PrPSc in the brain parenchyma is the major cause of neuronal degeneration. The mechanism by which PrPSc is transmitted, propagates, and causes neurodegenerative changes has been investigated over the years, and several clues have emerged. Efforts are also ongoing for identifying specific and sensitive diagnostic tests for sCJD and animal prion disorders, but success has been limited. The eye is suitable for these evaluations because it shares several anatomical and physiological features with the brain, and can be observed in vivo during disease progression. The retina, considered an extension of the central nervous system, is involved extensively in prion disorders. Accordingly, Optical Coherence Tomography and electroretinogram have shown some promise as pre-mortem diagnostic tests for human and animal prion disorders. However, a complete understanding of the physiology of PrPC and pathobiology of PrPSc in the eye is essential for developing specific and sensitive tests. Below, we summarize recent progress in ocular physiology and pathology in prion disorders, and the eye as an anatomically accessible site to diagnose, monitor disease progression, and test therapeutic options.
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Affiliation(s)
- Neena Singh
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
| | - Suman Chaudhary
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ajay Ashok
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ewald Lindner
- Department of Ophthalmology, Medical University of Graz, Auenbruggerplatz 4, 8036, Graz, Austria
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Jin J, Smith MD, Kersbergen CJ, Kam TI, Viswanathan M, Martin K, Dawson TM, Dawson VL, Zack DJ, Whartenby K, Calabresi PA. Glial pathology and retinal neurotoxicity in the anterior visual pathway in experimental autoimmune encephalomyelitis. Acta Neuropathol Commun 2019; 7:125. [PMID: 31366377 PMCID: PMC6670238 DOI: 10.1186/s40478-019-0767-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/06/2019] [Indexed: 12/23/2022] Open
Abstract
The animal model experimental autoimmune encephalomyelitis (EAE) has been used extensively in the past to test mechanisms that target peripheral immune cells for treatment of multiple sclerosis (MS). While there have been some notable successes in relapsing MS, the development of therapies for progressive multiple sclerosis (MS) has been hampered by lack of an appropriate animal model. Further, the mechanisms underlying CNS inflammation and neuronal injury remain incompletely elucidated. It is known that the MOG 35-55 EAE mouse model does not have insidious behavioral progression as occurs in people with MS, but there is significant neuronal and axonal injury in EAE, as a result of the inflammation. In the present study, we describe the time course of glial activation and retinal neurodegeneration in the EAE model, and highlight the utility of studying the anterior visual pathway for modeling mechanisms of neuronal injury that may recapitulate critical aspects of the pathology described in people with MS following optic neuritis and subclinical optic neuropathy. We show that A1 neurotoxic astrocytes are prevalent in optic nerve tissue and retina, and are associated with subsequent RGC loss in the most commonly used form of the EAE model induced by MOG 35-55 peptide in C57/B6 mice. We developed a semi-automatic method to quantify retinal ganglion cells (RGC) and show that RGCs remain intact at peak EAE (PID 16) but are significantly reduced in late EAE (PID 42). Postsynaptic proteins and neurites were also compromised in the retina of late EAE mice. The retinal pathology manifests weeks after the microglial and astrocyte activation, which were prominent in optic nerve tissues at PID 16. Microglia expressed iNOS and had increased gene expression of C1q, TNF-α, and IL-1α. Astrocytes expressed high levels of complement component 3 and other genes associated with A1 neurotoxic astrocytes. Our data suggest that EAE can be used to study the pathobiology of optic neuropathy and to examine the preclinical neuroprotective effects of drugs that target activation of neurotoxic A1 astrocytes.
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