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Qi C, Ren H, Fan Y. Microglia specific alternative splicing alterations in multiple sclerosis. Aging (Albany NY) 2024; 16:11656-11667. [PMID: 39115871 PMCID: PMC11346782 DOI: 10.18632/aging.206045] [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] [Received: 03/09/2024] [Accepted: 07/17/2024] [Indexed: 08/22/2024]
Abstract
Several aberrant alternative splicing (AS) events and their regulatory mechanisms are widely recognized in multiple sclerosis (MS). Yet the cell-type specific AS events have not been extensively examined. Here we assessed the diversity of AS events using web-based RNA-seq data of sorted CD15-CD11b+ microglia in white matter (WM) region from 10 patients with MS and 11 control subjects. The GSE111972 dataset was downloaded from GEO and ENA databases, aligned to the GRCh38 reference genome from ENSEMBL via STAR. rMATS was used to assess five types of AS events, alternative 3'SS (A3SS), alternative 5'SS (A5SS), skipped exon (SE), retained intron (RI) and mutually exclusive exons (MXE), followed by visualizing with rmats2sashimiplot and maser. Differential genes or transcripts were analyzed using the limma R package. Gene ontology (GO) analysis was performed with the clusterProfiler R package. 42,663 raw counts of AS events were identified and 132 significant AS events were retained based on the filtered criteria: 1) average coverage >10 and 2) delta percent spliced in (ΔPSI) >0.1. SE was the most common AS event (36.36%), followed by MXE events (32.58%), and RI (18.94%). Genes related to telomere maintenance and organization primarily underwent SE splicing, while genes associated with protein folding and mitochondrion organization were predominantly spliced in the MXE pattern. Conversely, genes experiencing RI were enriched in immune response and immunoglobulin production. In conclusion, we identified microglia-specific AS changes in the white matter of MS patients, which may shed light on novel pathological mechanisms underlying MS.
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Affiliation(s)
- Caiyun Qi
- Department of Obstetrics and Gynecology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, Guangdong-Hong Kong-Macao Greater Bay Area Higher Education Joint Laboratory of Maternal-Fetal Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Honglei Ren
- Department of Neurology, Tianjin Neurological Institute, Tianjin Institute of Immunology, State Key Laboratory of Experimental Hematology, Haihe Laboratory of Cell Ecosystem, Tianjin Medical University General Hospital, Tianjin, China
| | - Yong Fan
- Department of Obstetrics and Gynecology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, Guangdong-Hong Kong-Macao Greater Bay Area Higher Education Joint Laboratory of Maternal-Fetal Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
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2
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Woo MS, Engler JB, Friese MA. The neuropathobiology of multiple sclerosis. Nat Rev Neurosci 2024; 25:493-513. [PMID: 38789516 DOI: 10.1038/s41583-024-00823-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2024] [Indexed: 05/26/2024]
Abstract
Chronic low-grade inflammation and neuronal deregulation are two components of a smoldering disease activity that drives the progression of disability in people with multiple sclerosis (MS). Although several therapies exist to dampen the acute inflammation that drives MS relapses, therapeutic options to halt chronic disability progression are a major unmet clinical need. The development of such therapies is hindered by our limited understanding of the neuron-intrinsic determinants of resilience or vulnerability to inflammation. In this Review, we provide a neuron-centric overview of recent advances in deciphering neuronal response patterns that drive the pathology of MS. We describe the inflammatory CNS environment that initiates neurotoxicity by imposing ion imbalance, excitotoxicity and oxidative stress, and by direct neuro-immune interactions, which collectively lead to mitochondrial dysfunction and epigenetic dysregulation. The neuronal demise is further amplified by breakdown of neuronal transport, accumulation of cytosolic proteins and activation of cell death pathways. Continuous neuronal damage perpetuates CNS inflammation by activating surrounding glia cells and by directly exerting toxicity on neighbouring neurons. Further, we explore strategies to overcome neuronal deregulation in MS and compile a selection of neuronal actuators shown to impact neurodegeneration in preclinical studies. We conclude by discussing the therapeutic potential of targeting such neuronal actuators in MS, including some that have already been tested in interventional clinical trials.
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Affiliation(s)
- Marcel S Woo
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Jan Broder Engler
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Manuel A Friese
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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3
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Di Pietro AA, Pasquini LA. A novel in vitro model for investigating oligodendroglial maturation and myelin deposition under demyelinating and remyelinating conditions: Impact of microglial depletion and repopulation. Mol Cell Neurosci 2024; 129:103937. [PMID: 38796120 DOI: 10.1016/j.mcn.2024.103937] [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] [Received: 02/26/2024] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 05/28/2024] Open
Abstract
Experimental models of multiple sclerosis (MS) have significantly contributed to our understanding of pathophysiology and the development of therapeutic interventions. Various in vivo animal models have successfully replicated key features of MS and associated pathophysiological processes, shedding light on the sequence of events leading to disease initiation, progression, and resolution. Nevertheless, these models often entail substantial costs and prolonged treatment periods. In contrast, in vitro models offer distinct advantages, including cost-effectiveness and precise control over experimental conditions, thereby facilitating more reproducible results. We have developed a novel in vitro model tailored to the study of oligodendroglial maturation and myelin deposition under demyelinating and remyelinating conditions, which encompasses all the cell types present in the central nervous system (CNS). Of note, our model enables the evaluation of microglial cell commitment through a protocol involving their depletion and subsequent repopulation. Given that the development and survival of microglia are critically reliant on colony-stimulating factor-1 receptor (CSF-1R) signaling, we have employed CSF-1R inhibition to effectively deplete microglia. This versatile model holds promise for the assessment of potential therapies aimed at promoting oligodendroglial differentiation to safeguard and repair myelin, hence mitigate neurodegenerative processes.
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Affiliation(s)
- Anabella Ayelen Di Pietro
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica Patológica, Buenos Aires, Argentina; Universidad de Buenos Airess, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini, Facultad de Farmacia y Bioquímica, Buenos Aire, Argentina.
| | - Laura Andrea Pasquini
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica Patológica, Buenos Aires, Argentina; Universidad de Buenos Airess, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini, Facultad de Farmacia y Bioquímica, Buenos Aire, Argentina.
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Weyer MP, Strehle J, Schäfer MKE, Tegeder I. Repurposing of pexidartinib for microglia depletion and renewal. Pharmacol Ther 2024; 253:108565. [PMID: 38052308 DOI: 10.1016/j.pharmthera.2023.108565] [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] [Received: 09/28/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/07/2023]
Abstract
Pexidartinib (PLX3397) is a small molecule receptor tyrosine kinase inhibitor of colony stimulating factor 1 receptor (CSF1R) with moderate selectivity over other members of the platelet derived growth factor receptor family. It is approved for treatment of tenosynovial giant cell tumors (TGCT). CSF1R is highly expressed by microglia, which are macrophages of the central nervous system (CNS) that defend the CNS against injury and pathogens and contribute to synapse development and plasticity. Challenged by pathogens, apoptotic cells, debris, or inflammatory molecules they adopt a responsive state to propagate the inflammation and eventually return to a homeostatic state. The phenotypic switch may fail, and disease-associated microglia contribute to the pathophysiology in neurodegenerative or neuropsychiatric diseases or long-lasting detrimental brain inflammation after brain, spinal cord or nerve injury or ischemia/hemorrhage. Microglia also contribute to the growth permissive tumor microenvironment of glioblastoma (GBM). In rodents, continuous treatment for 1-2 weeks via pexidartinib food pellets leads to a depletion of microglia and subsequent repopulation from the remaining fraction, which is aided by peripheral monocytes that search empty niches for engraftment. The putative therapeutic benefit of such microglia depletion or forced renewal has been assessed in almost any rodent model of CNS disease or injury or GBM with heterogeneous outcomes, but a tendency of partial beneficial effects. So far, microglia monitoring e.g. via positron emission imaging is not standard of care for patients receiving Pexidartinib (e.g. for TGCT), so that the depletion and repopulation efficiency in humans is still largely unknown. Considering the virtuous functions of microglia, continuous depletion is likely no therapeutic option but short-lasting transient partial depletion to stimulate microglia renewal or replace microglia in genetic disease in combination with e.g. stem cell transplantation or as part of a multimodal concept in treatment of glioblastoma appears feasible. The present review provides an overview of the preclinical evidence pro and contra microglia depletion as a therapeutic approach.
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Affiliation(s)
- Marc-Philipp Weyer
- Institute of Clinical Pharmacology, Goethe-University Frankfurt, Faculty of Medicine, Frankfurt, Germany
| | - Jenny Strehle
- Department of Anesthesiology, University Medical Center Johannes Gutenberg-University Mainz, Germany
| | - Michael K E Schäfer
- Department of Anesthesiology, University Medical Center Johannes Gutenberg-University Mainz, Germany
| | - Irmgard Tegeder
- Institute of Clinical Pharmacology, Goethe-University Frankfurt, Faculty of Medicine, Frankfurt, Germany.
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5
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Wies Mancini VSB, Mattera VS, Pasquini JM, Pasquini LA, Correale JD. Microglia-derived extracellular vesicles in homeostasis and demyelination/remyelination processes. J Neurochem 2024; 168:3-25. [PMID: 38055776 DOI: 10.1111/jnc.16011] [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: 07/12/2023] [Revised: 10/10/2023] [Accepted: 11/03/2023] [Indexed: 12/08/2023]
Abstract
Microglia (MG) play a crucial role as the predominant myeloid cells in the central nervous system and are commonly activated in multiple sclerosis. They perform essential functions under normal conditions, such as actively surveying the surrounding parenchyma, facilitating synaptic remodeling, engulfing dead cells and debris, and protecting the brain against infectious pathogens and harmful self-proteins. Extracellular vesicles (EVs) are diverse structures enclosed by a lipid bilayer that originate from intracellular endocytic trafficking or the plasma membrane. They are released by cells into the extracellular space and can be found in various bodily fluids. EVs have recently emerged as a communication mechanism between cells, enabling the transfer of functional proteins, lipids, different RNA species, and even fragments of DNA from donor cells. MG act as both source and recipient of EVs. Consequently, MG-derived EVs are involved in regulating synapse development and maintaining homeostasis. These EVs also directly influence astrocytes, significantly increasing the release of inflammatory cytokines like IL-1β, IL-6, and TNF-α, resulting in a robust inflammatory response. Furthermore, EVs derived from inflammatory MG have been found to inhibit remyelination, whereas Evs produced by pro-regenerative MG effectively promote myelin repair. This review aims to provide an overview of the current understanding of MG-derived Evs, their impact on neighboring cells, and the cellular microenvironment in normal conditions and pathological states, specifically focusing on demyelination and remyelination processes.
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Affiliation(s)
- V S B Wies Mancini
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Cátedra de Química Biológica Patológica, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - V S Mattera
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Cátedra de Química Biológica Patológica, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - J M Pasquini
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Cátedra de Química Biológica Patológica, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - L A Pasquini
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Cátedra de Química Biológica Patológica, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - J D Correale
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Cátedra de Química Biológica Patológica, Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Neurología, Fleni, Buenos Aires, Argentina
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6
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Distéfano-Gagné F, Bitarafan S, Lacroix S, Gosselin D. Roles and regulation of microglia activity in multiple sclerosis: insights from animal models. Nat Rev Neurosci 2023:10.1038/s41583-023-00709-6. [PMID: 37268822 DOI: 10.1038/s41583-023-00709-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2023] [Indexed: 06/04/2023]
Abstract
As resident macrophages of the CNS, microglia are critical immune effectors of inflammatory lesions and associated neural dysfunctions. In multiple sclerosis (MS) and its animal models, chronic microglial inflammatory activity damages myelin and disrupts axonal and synaptic activity. In contrast to these detrimental effects, the potent phagocytic and tissue-remodelling capabilities of microglia support critical endogenous repair mechanisms. Although these opposing capabilities have long been appreciated, a precise understanding of their underlying molecular effectors is only beginning to emerge. Here, we review recent advances in our understanding of the roles of microglia in animal models of MS and demyelinating lesions and the mechanisms that underlie their damaging and repairing activities. We also discuss how the structured organization and regulation of the genome enables complex transcriptional heterogeneity within the microglial cell population at demyelinating lesions.
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Affiliation(s)
- Félix Distéfano-Gagné
- Axe Neuroscience, Centre de Recherche du CHU de Québec - Université Laval, Québec, Québec, Canada
- Département de Médecine Moléculaire de la Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Sara Bitarafan
- Axe Neuroscience, Centre de Recherche du CHU de Québec - Université Laval, Québec, Québec, Canada
- Département de Médecine Moléculaire de la Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Steve Lacroix
- Axe Neuroscience, Centre de Recherche du CHU de Québec - Université Laval, Québec, Québec, Canada
- Département de Médecine Moléculaire de la Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - David Gosselin
- Axe Neuroscience, Centre de Recherche du CHU de Québec - Université Laval, Québec, Québec, Canada.
- Département de Médecine Moléculaire de la Faculté de Médecine, Université Laval, Québec, Québec, Canada.
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7
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Chadarevian JP, Lombroso SI, Peet GC, Hasselmann J, Tu C, Marzan DE, Capocchi J, Purnell FS, Nemec KM, Lahian A, Escobar A, England W, Chaluvadi S, O'Brien CA, Yaqoob F, Aisenberg WH, Porras-Paniagua M, Bennett ML, Davtyan H, Spitale RC, Blurton-Jones M, Bennett FC. Engineering an inhibitor-resistant human CSF1R variant for microglia replacement. J Exp Med 2023; 220:e20220857. [PMID: 36584406 DOI: 10.1084/jem.20220857] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 11/11/2022] [Accepted: 12/13/2022] [Indexed: 12/31/2022] Open
Abstract
Hematopoietic stem cell transplantation (HSCT) can replace endogenous microglia with circulation-derived macrophages but has high mortality. To mitigate the risks of HSCT and expand the potential for microglia replacement, we engineered an inhibitor-resistant CSF1R that enables robust microglia replacement. A glycine to alanine substitution at position 795 of human CSF1R (G795A) confers resistance to multiple CSF1R inhibitors, including PLX3397 and PLX5622. Biochemical and cell-based assays show no discernable gain or loss of function. G795A- but not wildtype-CSF1R expressing macrophages efficiently engraft the brain of PLX3397-treated mice and persist after cessation of inhibitor treatment. To gauge translational potential, we CRISPR engineered human-induced pluripotent stem cell-derived microglia (iMG) to express G795A. Xenotransplantation studies demonstrate that G795A-iMG exhibit nearly identical gene expression to wildtype iMG, respond to inflammatory stimuli, and progressively expand in the presence of PLX3397, replacing endogenous microglia to fully occupy the brain. In sum, we engineered a human CSF1R variant that enables nontoxic, cell type, and tissue-specific replacement of microglia.
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Affiliation(s)
- Jean Paul Chadarevian
- Department of Neurobiology & Behavior, University of California, Irvine , Irvine, CA, USA
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine , Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - Sonia I Lombroso
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
- Pharmacology Graduate Group, Biomedical Graduate Studies Program, University of Pennsylvania , Philadelphia, PA, USA
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania , Philadelphia, PA, USA
| | - Graham C Peet
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
- Neuroscience Graduate Program and Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus , Aurora, CO, USA
| | - Jonathan Hasselmann
- Department of Neurobiology & Behavior, University of California, Irvine , Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - Christina Tu
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine , Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - Dave E Marzan
- Department of Biology, The College of New Jersey , Ewing, NJ, USA
| | - Joia Capocchi
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine , Irvine, CA, USA
| | - Freddy S Purnell
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
| | - Kelsey M Nemec
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
- Department of Neuroscience, Perelman School of Medicine , Philadelphia, PA, USA
| | - Alina Lahian
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine , Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - Adrian Escobar
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - Whitney England
- Department of Pharmaceutical Sciences, University of California, Irvine , Irvine, CA, USA
| | - Sai Chaluvadi
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
- Department of Neuroscience, Perelman School of Medicine , Philadelphia, PA, USA
| | - Carleigh A O'Brien
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
| | - Fazeela Yaqoob
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
| | - William H Aisenberg
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
| | | | - Mariko L Bennett
- Department of Neuroscience, Perelman School of Medicine , Philadelphia, PA, USA
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia, PA, USA
| | - Hayk Davtyan
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine , Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - Robert C Spitale
- Department of Pharmaceutical Sciences, University of California, Irvine , Irvine, CA, USA
| | - Mathew Blurton-Jones
- Department of Neurobiology & Behavior, University of California, Irvine , Irvine, CA, USA
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine , Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine , Irvine, CA, USA
| | - F Chris Bennett
- Department of Psychiatry, Perelman School of Medicine , University of Pennsylvania, Philadelphia, PA, USA
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia, PA, USA
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Pasquini L, Wies Mancini VB, Di Pietro A. Microglia depletion as a therapeutic strategy: friend or foe in multiple sclerosis models? Neural Regen Res 2023; 18:267-272. [PMID: 35900401 PMCID: PMC9396475 DOI: 10.4103/1673-5374.346538] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Multiple sclerosis is a chronic central nervous system demyelinating disease whose onset and progression are driven by a combination of immune dysregulation, genetic predisposition, and environmental factors. The activation of microglia and astrocytes is a key player in multiple sclerosis immunopathology, playing specific roles associated with anatomical location and phase of the disease and controlling demyelination and neurodegeneration. Even though reactive microglia can damage tissue and heighten deleterious effects and neurodegeneration, activated microglia also perform neuroprotective functions such as debris phagocytosis and growth factor secretion. Astrocytes can be activated into pro-inflammatory phenotype A1 through a mechanism mediated by activated neuroinflammatory microglia, which could also mediate neurodegeneration. This A1 phenotype inhibits oligodendrocyte proliferation and differentiation and is toxic to both oligodendrocytes and neurons. However, astroglial activation into phenotype A2 may also take place in response to neurodegeneration and as a protective mechanism. A variety of animal models mimicking specific multiple sclerosis features and the associated pathophysiological processes have helped establish the cascades of events that lead to the initiation, progression, and resolution of the disease. The colony-stimulating factor-1 receptor is expressed by myeloid lineage cells such as peripheral monocytes and macrophages and central nervous system microglia. Importantly, as microglia development and survival critically rely on colony-stimulating factor-1 receptor signaling, colony-stimulating factor-1 receptor inhibition can almost completely eliminate microglia from the brain. In this context, the present review discusses the impact of microglial depletion through colony-stimulating factor-1 receptor inhibition on demyelination, neurodegeneration, astroglial activation, and behavior in different multiple sclerosis models, highlighting the diversity of microglial effects on the progression of demyelinating diseases and the strengths and weaknesses of microglial modulation in therapy design.
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de Olmos S, Lorenzo A. Developing the theory of the extended amygdala with the use of the cupric-silver technique. JOURNAL OF THE HISTORY OF THE NEUROSCIENCES 2023; 32:19-38. [PMID: 36476105 DOI: 10.1080/0964704x.2022.2133569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The amygdaloid complex is a crucial component of the basal forebrain that participates in the modulation of many homeostatic functions, emotional behaviors, and learning. These features require a widespread pattern of connections with several brain structures. In the past, the amygdaloid complex was divided into corticomedial and basolateral groups. The existence of a neuronal continuum linking the central amygdaloid nucleus to the lateral bed nucleus of stria terminalis through the subpallidal area was first revealed by José de Olmos (1932-2008) with the aid of his cupric-silver technique. This observation gave birth to the concept of the extended amygdala, a conceptual framework that is useful for understanding the anatomofunctional organization of the amygdaloid complex, with relevance for basic neuroscience and clinical interventions. Traditional tract-tracing staining methods were complicated and tedious to reproduce. Axonal terminal endings were lost among a myriad of normal fibers. The need to visualize these terminals drove de Olmos to develop cupric-silver methods that revealed disintegrating synaptic terminals, without staining normal fibers. In this article, we describe the historical events leading to the development of the cupric-silver technique that evolved into the amino-cupric-silver technique, which developed hand-in-hand over the years.
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Affiliation(s)
- Soledad de Olmos
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Alfredo Lorenzo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
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