301
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Mutant superoxide dismutase aggregates from human spinal cord transmit amyotrophic lateral sclerosis. Acta Neuropathol 2018; 136:939-953. [PMID: 30284034 PMCID: PMC6280858 DOI: 10.1007/s00401-018-1915-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/21/2018] [Accepted: 09/21/2018] [Indexed: 12/13/2022]
Abstract
Motor neurons containing aggregates of superoxide dismutase 1 (SOD1) are hallmarks of amyotrophic lateral sclerosis (ALS) caused by mutations in the gene encoding SOD1. We have previously reported that two strains of mutant human (h) SOD1 aggregates (denoted A and B) can arise in hSOD1-transgenic models for ALS and that inoculation of such aggregates into the lumbar spinal cord of mice results in rostrally spreading, templated hSOD1 aggregation and premature fatal ALS-like disease. Here, we explored whether mutant hSOD1 aggregates with prion-like properties also exist in human ALS. Aggregate seeds were prepared from spinal cords from an ALS patient carrying the hSOD1G127Gfs*7 truncation mutation and from mice transgenic for the same mutation. To separate from mono-, di- or any oligomeric hSOD1 species, the seed preparation protocol included ultracentrifugation through a density cushion. The core structure of hSOD1G127Gfs*7 aggregates present in mice was strain A-like. Inoculation of the patient- or mouse-derived seeds into lumbar spinal cord of adult hSOD1-expressing mice induced strain A aggregation propagating along the neuraxis and premature fatal ALS-like disease (p < 0.0001). Inoculation of human or murine control seeds had no effect. The potencies of the ALS patient-derived seed preparations were high and disease was initiated in the transgenic mice by levels of hSOD1G127Gfs*7 aggregates much lower than those found in the motor system of patients carrying the mutation. The results suggest that prion-like growth and spread of hSOD1 aggregation could be the primary pathogenic mechanism, not only in hSOD1 transgenic rodent models, but also in human ALS.
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302
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O'Neil SM, Witcher KG, McKim DB, Godbout JP. Forced turnover of aged microglia induces an intermediate phenotype but does not rebalance CNS environmental cues driving priming to immune challenge. Acta Neuropathol Commun 2018; 6:129. [PMID: 30477578 PMCID: PMC6260864 DOI: 10.1186/s40478-018-0636-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 11/17/2018] [Indexed: 01/23/2023] Open
Abstract
Microglia are the resident innate immune cells of the central nervous system. Limited turnover throughout the lifespan leaves microglia susceptible to age-associated dysfunction. Indeed, we and others have reported microglia develop a pro-inflammatory or "primed" profile with age, characterized by increased expression of inflammatory mediators (e.g., MHC-II, CD68, IL-1β). Moreover, immune challenge with lipopolysaccharide (LPS) causes an exaggerated and prolonged neuroinflammatory response mediated by primed microglia in the aged brain. Recent studies show colony-stimulating factor 1 receptor (CSF1R) antagonism results in rapid depletion of microglia without significant complications. Therefore, we hypothesized that CSF1R antagonist-mediated depletion of microglia in the aged brain would result in repopulation with new and unprimed microglia. Here we provide novel evidence that microglia in the brain of adult (6-8 weeks old) and aged (16-18 months old) BALB/c mice were depleted following 3-week oral PLX5622 administration. When CSF1R antagonism was stopped, microglia repopulated equally in the adult and aged brain. Microglial depletion and repopulation reversed age-associated increases in microglial CD68+ lysosome enlargement and lipofuscin accumulation. Microglia-specific RNA sequencing revealed 511 differentially expressed genes with age. Of these, 117 genes were reversed by microglial repopulation (e.g., Apoe, Tgfb2, Socs3). Nevertheless, LPS challenge still induced an exaggerated microglial inflammatory response in the aged brain compared to adults. RNA sequencing of whole-brain tissue revealed an age-induced inflammatory signature, including reactive astrocytes, that was not restored by microglial depletion and repopulation. Furthermore, the microenvironment of the aged brain produced soluble factors that influenced developing microglia ex vivo and induced a profile primed to LPS challenge. Thus, the aged brain microenvironment promotes microglial priming despite repopulation of new microglia. Collectively, aged microglia proliferate and repopulate the brain, but these new cells still adopt a pro-inflammatory profile in the aged brain.
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Affiliation(s)
- Shane M O'Neil
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Kristina G Witcher
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Daniel B McKim
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jonathan P Godbout
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Institute for Behavioral Medicine Research, The Ohio State University Wexner Medical Center, 231 IBMR Building, 460 Medical Center Drive, Columbus, OH, 43210, USA.
- Chronic Brain Injury Program, The Ohio State University, Columbus, OH, USA.
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303
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Groh J, Klein D, Berve K, West BL, Martini R. Targeting microglia attenuates neuroinflammation-related neural damage in mice carrying human PLP1
mutations. Glia 2018; 67:277-290. [DOI: 10.1002/glia.23539] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 08/28/2018] [Accepted: 09/11/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Janos Groh
- Department of Neurology, Section of Developmental Neurobiology; University Hospital Wuerzburg; Wuerzburg Germany
| | - Dennis Klein
- Department of Neurology, Section of Developmental Neurobiology; University Hospital Wuerzburg; Wuerzburg Germany
| | - Kristina Berve
- Department of Neurology, Section of Developmental Neurobiology; University Hospital Wuerzburg; Wuerzburg Germany
| | | | - Rudolf Martini
- Department of Neurology, Section of Developmental Neurobiology; University Hospital Wuerzburg; Wuerzburg Germany
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304
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Garner KM, Amin R, Johnson RW, Scarlett EJ, Burton MD. Microglia priming by interleukin-6 signaling is enhanced in aged mice. J Neuroimmunol 2018; 324:90-99. [PMID: 30261355 PMCID: PMC6699492 DOI: 10.1016/j.jneuroim.2018.09.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/17/2018] [Accepted: 09/10/2018] [Indexed: 01/20/2023]
Abstract
During peripheral infection, excessive production of pro-inflammatory cytokines in the aged brain from primed microglia induces exaggerated behavioral pathologies. While the pro-inflammatory cytokine IL-6 increases in the brain with age, its role in microglia priming is not known. This study examined the functional role of IL-6 signaling on microglia priming. Our hypothesis is that IL-6 signaling mediates primed states of microglia in the aged. An initial study assessed age-related alteration in IL-6 signaling molecules; sIL-6R and sgp130 were measured in cerebrospinal fluid of young and aged wild-type animals. Subsequent studies of isolated microglia from C57BL6/J (IL-6+/+) and IL-6 knock-out (IL-6-/-) mice showed significantly less MHC-II expression in aged IL-6-/- compared to IL-6+/+ counterparts. Additionally, adult and aged IL-6+/+ and IL-6-/- animals were administered lipopolysaccharide (LPS) to simulate a peripheral infection; sickness behaviors and hippocampal cytokine gene expression were measured over a 24 h period. Aged IL-6-/- animals were resilient to LPS-induced sickness behaviors and recovered more quickly than IL-6+/+ animals. The age-associated baseline increase of IL-1β gene expression was ablated in aged IL-6-/- mice, suggesting IL-6 is a key driver of cytokine activity from primed microglia in the aged brain. We employed in vitro studies to understand molecular mechanisms in priming factors. MHC-II and pro-inflammatory gene expression (IL-1β, IL-10, IL-6) were measured after treating BV.2 microglia with sIL-6R and IL-6 or IL-6 alone. sIL-6R enhanced expression of both pro-inflammatory genes and MHC-II. Taken together, these data suggest IL-6 expression throughout life is involved in microglia priming and increased amounts of IL-6 following peripheral LPS challenge are involved in exaggerated sickness behaviors in the aged.
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Affiliation(s)
- Katherine M Garner
- Laboratory of Neuroimmunolgy and Behavior, School of Behavioral and Brain Sciences and Center for Advanced Pain Studies, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, United States
| | - Ravi Amin
- Laboratory of Integrative Immunology and Behavior, Animal Science Department, University of Illinois at Urbana-Champaign, 7 Animal Sciences Lab 1207 W. Gregory Dr., Urbana, IL 61801, USA
| | - Rodney W Johnson
- Laboratory of Neuroimmunolgy and Behavior, School of Behavioral and Brain Sciences and Center for Advanced Pain Studies, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, United States; Laboratory of Integrative Immunology and Behavior, Animal Science Department, University of Illinois at Urbana-Champaign, 7 Animal Sciences Lab 1207 W. Gregory Dr., Urbana, IL 61801, USA
| | - Emily J Scarlett
- Laboratory of Neuroimmunolgy and Behavior, School of Behavioral and Brain Sciences and Center for Advanced Pain Studies, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, United States
| | - Michael D Burton
- Laboratory of Neuroimmunolgy and Behavior, School of Behavioral and Brain Sciences and Center for Advanced Pain Studies, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, United States.
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305
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Ugolini F, Lana D, Nardiello P, Nosi D, Pantano D, Casamenti F, Giovannini MG. Different Patterns of Neurodegeneration and Glia Activation in CA1 and CA3 Hippocampal Regions of TgCRND8 Mice. Front Aging Neurosci 2018; 10:372. [PMID: 30483118 PMCID: PMC6243135 DOI: 10.3389/fnagi.2018.00372] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/26/2018] [Indexed: 01/24/2023] Open
Abstract
We investigated the different patterns of neurodegeneration and glia activation in CA1 and CA3 hippocampal areas of TgCRND8 mice. The main feature of this transgenic model is the rapid development of the amyloid pathology, which starts already at 3 months of age. We performed immunohistochemical analyses to compare the different sensibility of the two hippocampal regions to neurodegeneration. We performed qualitative and quantitative evaluations by fluorescence immunohistochemistry with double or triple staining, followed by confocal microscopy and digital image analysis in stratum pyramidale (SP) and stratum radiatum (SR) of CA1 and CA3, separately. We evaluated time-dependent Aβ plaques deposition, expression of inflammatory markers, as well as quantitative and morphological alterations of neurons and glia in transgenic mice at 3 (Tg 3M) and 6 (Tg 6M) months of age, compared to WT mice. In CA1 SR of Tg 6M mice, we found significantly more Medium and Large plaques than in CA3. The pattern of neurodegeneration and astrocytes activation was different in the two areas, indicating higher sensitivity of CA1. In the CA1 SP of Tg 6M mice, we found signs of reactive astrogliosis, such as increase of astrocytes density in SP, increase of GFAP expression in SR, and elongation of astrocytes branches. We found also common patterns of glia activation and neurodegenerative processes in CA1 and CA3 of Tg 6M mice: significant increase of total and reactive microglia density in SP and SR, increased expression of TNFα, of iNOS, and IL1β in astrocytes and increased density of neurons-astrocytes-microglia triads. In CA1 SP, we found decrease of volume and number of pyramidal neurons, paralleled by increase of apoptosis, and, consequently, shrinkage of CA1 SP. These data demonstrate that in TgCRND8 mice, the responses of neurons and glia to neurodegenerative patterns induced by Aβ plaques deposition is not uniform in the two hippocampal areas, and in CA1 pyramidal neurons, the higher sensitivity may be related to the different plaque distribution in this area. All these modifications may be at the basis of memory loss, the peculiar symptom of AD, which was demonstrated in this transgenic mouse model of Aβ deposition, even at early stages.
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Affiliation(s)
- Filippo Ugolini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Daniele Lana
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Pamela Nardiello
- Department of Neuroscience, Psychology, Drug Research and Child Health, NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Daniele Nosi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Daniela Pantano
- Department of Neuroscience, Psychology, Drug Research and Child Health, NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Fiorella Casamenti
- Department of Neuroscience, Psychology, Drug Research and Child Health, NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Maria Grazia Giovannini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
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306
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Chad JA, Pasternak O, Salat DH, Chen JJ. Re-examining age-related differences in white matter microstructure with free-water corrected diffusion tensor imaging. Neurobiol Aging 2018; 71:161-170. [PMID: 30145396 PMCID: PMC6179151 DOI: 10.1016/j.neurobiolaging.2018.07.018] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/22/2018] [Accepted: 07/25/2018] [Indexed: 01/11/2023]
Abstract
Diffusion tensor imaging (DTI) has been used extensively to investigate white matter (WM) microstructural changes during healthy adult aging. However, WM fibers are known to shrink throughout the lifespan, leading to larger interstitial spaces with age. This could allow more extracellular free water molecules to bias DTI metrics, which are relied upon to provide WM microstructural information. Using a cohort of 212 participants, we demonstrate that WM microstructural changes in aging are potentially less pronounced than previously reported once the free water compartment is eliminated. After free water elimination, DTI parameters show age-related differences that match histological evidence of myelin degradation and debris accumulation. The fraction of free water is further shown to associate better with age than any of the conventional DTI parameters. Our findings suggest that DTI analyses involving free water are likely to yield novel insight into retrospective re-analysis of data and to answer new questions in ongoing DTI studies of brain aging.
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Affiliation(s)
- Jordan A Chad
- Rotman Research Institute, Baycrest Health Sciences, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
| | - Ofer Pasternak
- Departments of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - David H Salat
- MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA; Neuroimaging Research for Veterans Center, Boston VA, VA Healthcare System, Boston, MA, USA
| | - J Jean Chen
- Rotman Research Institute, Baycrest Health Sciences, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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307
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Age-Induced Spatial Memory Deficits in Rats Are Correlated with Specific Brain Region Alterations in Microglial Morphology and Gene Expression. J Neuroimmune Pharmacol 2018; 14:251-262. [DOI: 10.1007/s11481-018-9817-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/12/2018] [Indexed: 10/28/2022]
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308
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Chen M, Luo C, Zhao J, Devarajan G, Xu H. Immune regulation in the aging retina. Prog Retin Eye Res 2018; 69:159-172. [PMID: 30352305 DOI: 10.1016/j.preteyeres.2018.10.003] [Citation(s) in RCA: 157] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/13/2018] [Accepted: 10/19/2018] [Indexed: 12/24/2022]
Abstract
The retina is an immune privileged tissue, which is protected from external and internal insults by its blood-retina barriers and immune suppressive microenvironment. Apart from the avoidance and tolerance strategies, the retina is also protected by its own defense system, i.e., microglia and the complement system. The immune privilege and defense mechanisms work together to maintain retinal homeostasis. During aging, the retina is at an increased risk of developing various degenerative diseases such as age-related macular degeneration, diabetic retinopathy, and glaucomatous retinopathy. Previously, we have shown that aging induces a para-inflammatory response in the retina. In this review, we explore the impact of aging on retinal immune regulation and the connection between homeostatic control of retinal immune privilege and para-inflammation under aging conditions and present a view that may explain why aging puts the retina at risk of developing degenerative diseases.
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Affiliation(s)
- Mei Chen
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK
| | - Chang Luo
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK; Aier Eye Institute, Aier School of Ophthalmology, Central South University, China
| | - Jiawu Zhao
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK
| | | | - Heping Xu
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK; Aier Eye Institute, Aier School of Ophthalmology, Central South University, China.
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309
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Mishra A, Brinton RD. Inflammation: Bridging Age, Menopause and APOEε4 Genotype to Alzheimer's Disease. Front Aging Neurosci 2018; 10:312. [PMID: 30356809 PMCID: PMC6189518 DOI: 10.3389/fnagi.2018.00312] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/18/2018] [Indexed: 12/19/2022] Open
Abstract
Neuro-inflammatory processes that contribute to development of Alzheimer’s are evident early in the latent prodromal phase and worsen during the course of the disease. Despite substantial mechanistic and clinical evidence of inflammation, therapeutic approaches targeting inflammation have failed to alter the course of the disease. Disparate results from epidemiological and clinical trials targeting inflammation, highlight the complexity of the inflammatory process. Herein we review the dynamics of the inflammatory process across aging, midlife endocrine transitions, and the APOEε4 genotype and their contribution to progression of Alzheimer’s disease (AD). We discuss the chronic inflammatory processes that are activated during midlife chronological and endocrine aging, which ultimately limit the clearance capacity of microglia and lead to immune senescence. Aging, menopause, and APOEε4 combine the three hits of a compromised bioenergetic system of menopause with the chronic low grade innate inflammation of aging with the APOEε4 dyslipidemia and adaptive immune response. The inflammatory immune response is the unifying factor that bridges across each of the risk factors for AD. Immune system regulators that are specific to stage of disease and inflammatory phenotype would provide a therapeutic strategy to disconnect the bridge that drives disease. Outcomes of this analysis provide plausible mechanisms underlying failed clinical trials of anti-inflammatory agents in Alzheimer’s patients. Further, they highlight the need for stratifying AD clinical trial cohorts based on inflammatory phenotype. Combination therapies that include targeted use of anti-inflammatory agent’s specific to the immune phenotype are considered.
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Affiliation(s)
- Aarti Mishra
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA, United States.,Center for Innovation in Brain Science, University of Arizona, Tucson, AZ, United States
| | - Roberta D Brinton
- Center for Innovation in Brain Science, University of Arizona, Tucson, AZ, United States.,Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States.,Department of Neurology, College of Medicine, University of Arizona, Tucson, AZ, United States
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310
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Gu BJ, Wiley JS. P2X7 as a scavenger receptor for innate phagocytosis in the brain. Br J Pharmacol 2018; 175:4195-4208. [PMID: 30098011 DOI: 10.1111/bph.14470] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/20/2018] [Accepted: 07/25/2018] [Indexed: 12/29/2022] Open
Abstract
The P2X7 receptor has been widely studied for its ATP-induced pro-inflammatory effect, but in the absence of a ligand, P2X7 has a second function as a scavenger receptor, which is active in the development of the human brain. The scavenger activity of P2X7 is only evident in the absence of serum but is fully active in cerebrospinal fluid. P2X7 on the cell surface is present as a membrane complex, and an attachment to non-muscle myosin of the cytoskeleton is required for particle engulfment. Selective antagonists of P2X7 pro-inflammatory function have little effect on phagocytosis, but inheritance of a variant haplotype spanning the P2RX7 and P2RX4 genes has been associated with loss of P2X7-mediated phagocytosis. Recent studies in mice suggest that the innate phagocytosis mediated by P2X7 receptors declines with ageing. Thus, defective P2X7-mediated phagocytosis may contribute to age-related neuro-degenerative diseases including Alzheimer's disease, age-related macular degeneration and primary progressive multiple sclerosis.
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Affiliation(s)
- Ben J Gu
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - James S Wiley
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia
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311
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De Biase LM, Bonci A. Region-Specific Phenotypes of Microglia: The Role of Local Regulatory Cues. Neuroscientist 2018; 25:314-333. [PMID: 30280638 DOI: 10.1177/1073858418800996] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Microglia are ubiquitous, macrophage like cells within the central nervous system (CNS) that play critical roles in supporting neuronal health and viability. They can also influence neuronal membrane properties and synaptic connectivity, positioning microglia as key cellular players in both physiological and pathological contexts. Microglia have generally been assumed to be equivalent throughout the CNS, but accumulating evidence indicates that their properties vary substantially across distinct CNS regions. In comparison to our understanding of neuronal diversity and its functional importance, our knowledge about causes and consequences of microglial regional heterogeneity is extremely limited. To fully understand how microglia influence the function of specific neuronal populations and shape heightened susceptibility of some neurons to damage and disease, greater focus on microglial heterogeneity is needed.
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Affiliation(s)
- Lindsay M De Biase
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA.,Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Antonello Bonci
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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312
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Newcombe EA, Camats-Perna J, Silva ML, Valmas N, Huat TJ, Medeiros R. Inflammation: the link between comorbidities, genetics, and Alzheimer's disease. J Neuroinflammation 2018; 15:276. [PMID: 30249283 PMCID: PMC6154824 DOI: 10.1186/s12974-018-1313-3] [Citation(s) in RCA: 336] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 09/11/2018] [Indexed: 12/21/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disorder, most cases of which lack a clear causative event. This has made the disease difficult to characterize and, thus, diagnose. Although some cases are genetically linked, there are many diseases and lifestyle factors that can lead to an increased risk of developing AD, including traumatic brain injury, diabetes, hypertension, obesity, and other metabolic syndromes, in addition to aging. Identifying common factors and trends between these conditions could enhance our understanding of AD and lead to the development of more effective treatments. Although the immune system is one of the body’s key defense mechanisms, chronic inflammation has been increasingly linked with several age-related diseases. Moreover, it is now well accepted that chronic inflammation has an important role in the onset and progression of AD. In this review, the different inflammatory signals associated with AD and its risk factors will be outlined to demonstrate how chronic inflammation may be influencing individual susceptibility to AD. Our goal is to bring attention to potential shared signals presented by the immune system during different conditions that could lead to the development of successful treatments.
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Affiliation(s)
- Estella A Newcombe
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia.
| | - Judith Camats-Perna
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia
| | - Mallone L Silva
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia
| | - Nicholas Valmas
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Tee Jong Huat
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia.,Centre for Stem Cell Ageing and Regenerative Engineering, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Rodrigo Medeiros
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia.
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313
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Sousa C, Golebiewska A, Poovathingal SK, Kaoma T, Pires-Afonso Y, Martina S, Coowar D, Azuaje F, Skupin A, Balling R, Biber K, Niclou SP, Michelucci A. Single-cell transcriptomics reveals distinct inflammation-induced microglia signatures. EMBO Rep 2018; 19:embr.201846171. [PMID: 30206190 PMCID: PMC6216255 DOI: 10.15252/embr.201846171] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 08/17/2018] [Accepted: 08/22/2018] [Indexed: 01/10/2023] Open
Abstract
Microglia are specialized parenchymal‐resident phagocytes of the central nervous system (CNS) that actively support, defend and modulate the neural environment. Dysfunctional microglial responses are thought to worsen CNS diseases; nevertheless, their impact during neuroinflammatory processes remains largely obscure. Here, using a combination of single‐cell RNA sequencing and multicolour flow cytometry, we comprehensively profile microglia in the brain of lipopolysaccharide (LPS)‐injected mice. By excluding the contribution of other immune CNS‐resident and peripheral cells, we show that microglia isolated from LPS‐injected mice display a global downregulation of their homeostatic signature together with an upregulation of inflammatory genes. Notably, we identify distinct microglial activated profiles under inflammatory conditions, which greatly differ from neurodegenerative disease‐associated profiles. These results provide insights into microglial heterogeneity and establish a resource for the identification of specific phenotypes in CNS disorders, such as neuroinflammatory and neurodegenerative diseases.
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Affiliation(s)
- Carole Sousa
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg.,Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg.,Doctoral School of Science and Technology, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Anna Golebiewska
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg
| | - Suresh K Poovathingal
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg.,Single Cell Analytics & Microfluidics Core, Vlaams Instituut voor Biotechnologie-KU Leuven, Leuven, Belgium
| | - Tony Kaoma
- Proteome and Genome Research Unit, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg
| | - Yolanda Pires-Afonso
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg.,Doctoral School of Science and Technology, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Silvia Martina
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg
| | - Djalil Coowar
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg
| | - Francisco Azuaje
- Proteome and Genome Research Unit, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg
| | - Alexander Skupin
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg.,National Centre for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA
| | - Rudi Balling
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg
| | - Knut Biber
- Section Molecular Psychiatry, Department for Psychiatry and Psychotherapy, Laboratory of Translational Psychiatry, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Section Medical Physiology, Department of Neuroscience, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Simone P Niclou
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg.,Department of Biomedicine, KG Jebsen Brain Tumour Research Center, University of Bergen, Bergen, Norway
| | - Alessandro Michelucci
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg .,Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg
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314
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Laflamme N, Cisbani G, Préfontaine P, Srour Y, Bernier J, St-Pierre MK, Tremblay MÈ, Rivest S. mCSF-Induced Microglial Activation Prevents Myelin Loss and Promotes Its Repair in a Mouse Model of Multiple Sclerosis. Front Cell Neurosci 2018; 12:178. [PMID: 30018535 PMCID: PMC6037698 DOI: 10.3389/fncel.2018.00178] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 06/07/2018] [Indexed: 11/16/2022] Open
Abstract
A pathological hallmark of multiple sclerosis (MS) is myelin loss in brain white matter accompanied by compromised remyelination. Demyelinated lesions are deeply associated with oligodendrocyte apoptosis and a robust inflammatory response. Although various studies point towards a noxious role of inflammation in MS, others emphasize a positive role for the innate immune cells in disease progression. A cytokine well-known to stimulate cell survival, proliferation and differentiation of myeloid cells, macrophage colony-stimulating factor (mCSF), was administered to mice during a 5 week-long cuprizone diet. Treated mice exhibited reduced myelin loss during the demyelination phase, together with an increased number of microglia and oligodendrocyte precursor cells in lesion sites. Tamoxifen-induced conditional deletion of the mCSF receptor in microglia from cuprizone-fed mice caused aberrant myelin debris accumulation in the corpus callosum and reduced microglial phagocytic response. mCSF therefore plays a key role in stimulating myelin clearance by the brain innate immune cells, which is a prerequisite for proper remyelination and myelin repair processes.
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Affiliation(s)
- Nathalie Laflamme
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Giulia Cisbani
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Paul Préfontaine
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Younes Srour
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Jordan Bernier
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Marie-Kim St-Pierre
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Marie-Ève Tremblay
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
| | - Serge Rivest
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, Quebec, QC, Canada
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315
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Abstract
Glial cell types were classified less than 100 years ago by del Rio-Hortega. For instance, he correctly surmised that microglia in pathologic central nervous system (CNS) were "voracious monsters" that helped clean the tissue. Although these historical predictions were remarkably accurate, innovative technologies have revealed novel molecular, cellular, and dynamic physiologic aspects of CNS glia. In this review, we integrate recent findings regarding the roles of glia and glial interactions in healthy and injured spinal cord. The three major glial cell types are considered in healthy CNS and after spinal cord injury (SCI). Astrocytes, which in the healthy CNS regulate neurotransmitter and neurovascular dynamics, respond to SCI by becoming reactive and forming a glial scar that limits pathology and plasticity. Microglia, which in the healthy CNS scan for infection/damage, respond to SCI by promoting axon growth and remyelination-but also with hyperactivation and cytotoxic effects. Oligodendrocytes and their precursors, which in healthy tissue speed axon conduction and support axonal function, respond to SCI by differentiating and producing myelin, but are susceptible to death. Thus, post-SCI responses of each glial cell can simultaneously stimulate and stifle repair. Interestingly, potential therapies could also target interactions between these cells. Astrocyte-microglia cross-talk creates a feed-forward loop, so shifting the response of either cell could amplify repair. Astrocytes, microglia, and oligodendrocytes/precursors also influence post-SCI cell survival, differentiation, and remyelination, as well as axon sparing. Therefore, optimizing post-SCI responses of glial cells-and interactions between these CNS cells-could benefit neuroprotection, axon plasticity, and functional recovery.
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Affiliation(s)
- Andrew D Gaudet
- Department of Psychology and Neuroscience, University of Colorado Boulder, Muenzinger D244 | 345 UCB, Boulder, CO, 80309, USA.
- Center for Neuroscience, University of Colorado Boulder, Muenzinger D244 | 345 UCB, Boulder, CO, 80309, USA.
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX, 78712, USA
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316
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Rangaraju S, Dammer EB, Raza SA, Gao T, Xiao H, Betarbet R, Duong DM, Webster JA, Hales CM, Lah JJ, Levey AI, Seyfried NT. Quantitative proteomics of acutely-isolated mouse microglia identifies novel immune Alzheimer's disease-related proteins. Mol Neurodegener 2018; 13:34. [PMID: 29954413 PMCID: PMC6025801 DOI: 10.1186/s13024-018-0266-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 06/18/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Microglia are innate immune cells of the brain that perform phagocytic and inflammatory functions in disease conditions. Transcriptomic studies of acutely-isolated microglia have provided novel insights into their molecular and functional diversity in homeostatic and neurodegenerative disease states. State-of-the-art mass spectrometry methods can comprehensively characterize proteomic alterations in microglia in neurodegenerative disorders, potentially providing novel functionally relevant molecular insights that are not provided by transcriptomics. However, comprehensive proteomic profiling of adult primary microglia in neurodegenerative disease conditions has not been performed. METHODS We performed quantitative mass spectrometry based proteomic analyses of purified CD11b+ acutely-isolated microglia from adult (6 mo) mice in normal, acute neuroinflammatory (LPS-treatment) and chronic neurodegenerative states (5xFAD model of Alzheimer's disease [AD]). Differential expression analyses were performed to characterize specific microglial proteomic changes in 5xFAD mice and identify overlap with LPS-induced pro-inflammatory changes. Our results were also contrasted with existing proteomic data from wild-type mouse microglia and from existing microglial transcriptomic data from wild-type and 5xFAD mice. Neuropathological validation studies of select proteins were performed in human AD and 5xFAD brains. RESULTS Of 4133 proteins identified, 187 microglial proteins were differentially expressed in the 5xFAD mouse model of AD pathology, including proteins with previously known (Apoe, Clu and Htra1) as well as previously unreported relevance to AD biology (Cotl1 and Hexb). Proteins upregulated in 5xFAD microglia shared significant overlap with pro-inflammatory changes observed in LPS-treated mice. Several proteins increased in human AD brain were also upregulated by 5xFAD microglia (Aβ peptide, Apoe, Htra1, Cotl1 and Clu). Cotl1 was identified as a novel microglia-specific marker with increased expression and strong association with AD neuropathology. Apoe protein was also detected within plaque-associated microglia in which Apoe and Aβ were highly co-localized, suggesting a role for Apoe in phagocytic clearance of Aβ. CONCLUSIONS We report a comprehensive proteomic study of adult mouse microglia derived from acute neuroinflammation and AD models, representing a valuable resource to the neuroscience research community. We highlight shared and unique microglial proteomic changes in acute neuroinflammation aging and AD mouse models and identify novel roles for microglial proteins in human neurodegeneration.
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Affiliation(s)
| | - Eric B Dammer
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | - Syed Ali Raza
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Tianwen Gao
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Hailian Xiao
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Ranjita Betarbet
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Duc M Duong
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | - James A Webster
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Chadwick M Hales
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - James J Lah
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Allan I Levey
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Nicholas T Seyfried
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA. .,Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA.
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317
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Xie F, Zhang F, Min S, Chen J, Yang J, Wang X. Glial cell line-derived neurotrophic factor (GDNF) attenuates the peripheral neuromuscular dysfunction without inhibiting the activation of spinal microglia/monocyte. BMC Geriatr 2018; 18:110. [PMID: 29743034 PMCID: PMC5944173 DOI: 10.1186/s12877-018-0796-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 04/30/2018] [Indexed: 12/13/2022] Open
Abstract
Background Peripheral neuromuscular dysfunctions were found in elderly individuals, and spinal microglia/monocyte plays an important role on this process. This study aims to test whether the glial cell line-derived neurotrophic factor (GDNF) could attenuate age-related neuromuscular dysfunction by inhibiting the activation of spinal microglia/monocyte. Methods Male Sprague-Dawley rats were divided into an adult group and an aged group. The aged rats were intrathecally injected with normal saline (NS) and GDNF. All the rats were harvested 5 days after each injection. The muscular function was tested by compound muscle action potential, and the activation of microglia/monocyte was detected by immunofluorescence staining; cytokines were assayed by enzyme-linked immunosorbent assay; the expression level of GDNF and its known receptor GFR-α in the spinal cord, the expression level of neuregulin-1 (NRG-1) in the sciatic nerve, and the expression level of γ- and α7- ε-nicotinic acetylcholine receptors in the tibialis anterior muscle were measured by western blotting. Results The activated microglia/monocyte was found in the aged rats compared to the adult rats. The aged rats showed a significant neuromuscular dysfunction and cytokine release as well as increased expression of γ- and α7-nAChR. The protein expression of GDNF, GFR-α, and NRG-1 in the aged rats were significantly lower than that in the adult rats. However, the exogenous injection of GDNF could alleviate the neuromuscular dysfunction but not inhibit the activation of spinal microglia/monocyte. Furthermore, the levels of GFR-α and NRG-1 also increased after GDNF treatment. Conclusion The GDNF could attenuate the age-related peripheral neuromuscular dysfunction without inhibiting the activation of microglia/monocyte in the spinal cord.
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Affiliation(s)
- Fei Xie
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Friendship Road 1#, Yuan Jia Gang, Chongqing, 400016, China
| | - Fan Zhang
- Department of Anesthesiology, the People's Hospital of Jianyang City, Chengdu, Sichuan, China
| | - Su Min
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Friendship Road 1#, Yuan Jia Gang, Chongqing, 400016, China.
| | - Jingyuan Chen
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Friendship Road 1#, Yuan Jia Gang, Chongqing, 400016, China
| | - Jun Yang
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Friendship Road 1#, Yuan Jia Gang, Chongqing, 400016, China
| | - Xin Wang
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Friendship Road 1#, Yuan Jia Gang, Chongqing, 400016, China
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318
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Abstract
Microglia differentiate from progenitors that infiltrate the nascent CNS during early embryonic development. They then remain in this unique immune-privileged environment throughout life. Multiple immune mechanisms, which we collectively refer to as microglial checkpoints, ensure efficient and tightly regulated microglial responses to perturbations in the CNS milieu. Such mechanisms are essential for proper CNS development and optimal physiological function. However, in chronic disease or aging, when a robust immune response is required, such checkpoint mechanisms may limit the ability of microglia to protect the CNS. Here we survey microglial checkpoint mechanisms and their roles in controlling microglial function throughout life and in disease, and discuss how they may be targeted therapeutically.
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319
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Lowry JR, Klegeris A. Emerging roles of microglial cathepsins in neurodegenerative disease. Brain Res Bull 2018; 139:144-156. [DOI: 10.1016/j.brainresbull.2018.02.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 01/23/2018] [Accepted: 02/13/2018] [Indexed: 01/21/2023]
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320
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Garaschuk O, Semchyshyn HM, Lushchak VI. Healthy brain aging: Interplay between reactive species, inflammation and energy supply. Ageing Res Rev 2018; 43:26-45. [PMID: 29452266 DOI: 10.1016/j.arr.2018.02.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/13/2017] [Accepted: 02/08/2018] [Indexed: 02/07/2023]
Abstract
Brains' high energy expenditure with preferable utilization of glucose and ketone bodies, defines the specific features of its energy homeostasis. The extensive oxidative metabolism is accompanied by a concomitant generation of high amounts of reactive oxygen, nitrogen, and carbonyl species, which will be here collectively referred to as RONCS. Such metabolism in combination with high content of polyunsaturated fatty acids creates specific problems in maintaining brains' redox homeostasis. While the levels of products of interaction between RONCS and cellular components increase slowly during the first two trimesters of individuals' life, their increase is substantially accelerated towards the end of life. Here we review the main mechanisms controlling the redox homeostasis of the mammalian brain, their age-dependencies as well as their adaptive potential, which might turn out to be much higher than initially assumed. According to recent data, the organism seems to respond to the enhancement of aging-related toxicity by forming a new homeostatic set point. Therefore, further research will focus on understanding the properties of the new set point(s), the general nature of this phenomenon and will explore the limits of brains' adaptivity.
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Affiliation(s)
- O Garaschuk
- Department of Neurophysiology, Institute of Physiology, University of Tübingen, 72074 Tübingen, Germany.
| | - H M Semchyshyn
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str, Ivano-Frankivsk, 76018, Ukraine.
| | - V I Lushchak
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str, Ivano-Frankivsk, 76018, Ukraine.
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321
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Disease-Associated Microglia: A Universal Immune Sensor of Neurodegeneration. Cell 2018; 173:1073-1081. [DOI: 10.1016/j.cell.2018.05.003] [Citation(s) in RCA: 717] [Impact Index Per Article: 119.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/17/2018] [Accepted: 04/29/2018] [Indexed: 11/18/2022]
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322
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Macrophage Depletion Ameliorates Peripheral Neuropathy in Aging Mice. J Neurosci 2018; 38:4610-4620. [PMID: 29712789 DOI: 10.1523/jneurosci.3030-17.2018] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/06/2018] [Accepted: 03/09/2018] [Indexed: 01/02/2023] Open
Abstract
Aging is known as a major risk factor for the structure and function of the nervous system. There is urgent need to overcome such deleterious effects of age-related neurodegeneration. Here we show that peripheral nerves of 24-month-old aging C57BL/6 mice of either sex show similar pathological alterations as nerves from aging human individuals, whereas 12-month-old adult mice lack such alterations. Specifically, nerve fibers showed demyelination, remyelination and axonal lesion. Moreover, in the aging mice, neuromuscular junctions showed features typical for dying-back neuropathies, as revealed by a decline of presynaptic markers, associated with α-bungarotoxin-positive postsynapses. In line with these observations were reduced muscle strengths. These alterations were accompanied by elevated numbers of endoneurial macrophages, partially comprising the features of phagocytosing macrophages. Comparable profiles of macrophages could be identified in peripheral nerve biopsies of aging persons. To determine the pathological impact of macrophages in aging mice, we selectively targeted the cells by applying an orally administered CSF-1R specific kinase (c-FMS) inhibitor. The 6-month-lasting treatment started before development of degenerative changes at 18 months and reduced macrophage numbers in mice by ∼70%, without side effects. Strikingly, nerve structure was ameliorated and muscle strength preserved. We show, for the first time, that age-related degenerative changes in peripheral nerves are driven by macrophages. These findings may pave the way for treating degeneration in the aging peripheral nervous system by targeting macrophages, leading to reduced weakness, improved mobility, and eventually increased quality of life in the elderly.SIGNIFICANCE STATEMENT Aging is a major risk factor for the structure and function of the nervous system. Here we show that peripheral nerves of 24-month-old aging mice show similar degenerative alterations as nerves from aging human individuals. Both in mice and humans, these alterations were accompanied by endoneurial macrophages. To determine the pathological impact of macrophages in aging mice, we selectively targeted the cells by blocking a cytokine receptor, essential for macrophage survival. The treatment strongly reduced macrophage numbers and substantially improved nerve structure and muscle strength. We show, for the first time, that age-related degenerative changes in peripheral nerves are driven by macrophages. These findings may be helpful for treatment weakness and reduced mobility in the elderly.
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323
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Caprariello AV, Stys PK. Two steps forward for myelin repair in multiple sclerosis. Lancet Neurol 2018; 17:297-298. [DOI: 10.1016/s1474-4422(18)30070-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 02/02/2018] [Indexed: 11/30/2022]
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324
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Skaper SD, Facci L, Zusso M, Giusti P. An Inflammation-Centric View of Neurological Disease: Beyond the Neuron. Front Cell Neurosci 2018; 12:72. [PMID: 29618972 PMCID: PMC5871676 DOI: 10.3389/fncel.2018.00072] [Citation(s) in RCA: 301] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 02/27/2018] [Indexed: 12/13/2022] Open
Abstract
Inflammation is a complex biological response fundamental to how the body deals with injury and infection to eliminate the initial cause of cell injury and effect repair. Unlike a normally beneficial acute inflammatory response, chronic inflammation can lead to tissue damage and ultimately its destruction, and often results from an inappropriate immune response. Inflammation in the nervous system (“neuroinflammation”), especially when prolonged, can be particularly injurious. While inflammation per se may not cause disease, it contributes importantly to disease pathogenesis across both the peripheral (neuropathic pain, fibromyalgia) and central [e.g., Alzheimer disease, Parkinson disease, multiple sclerosis, motor neuron disease, ischemia and traumatic brain injury, depression, and autism spectrum disorder] nervous systems. The existence of extensive lines of communication between the nervous system and immune system represents a fundamental principle underlying neuroinflammation. Immune cell-derived inflammatory molecules are critical for regulation of host responses to inflammation. Although these mediators can originate from various non-neuronal cells, important sources in the above neuropathologies appear to be microglia and mast cells, together with astrocytes and possibly also oligodendrocytes. Understanding neuroinflammation also requires an appreciation that non-neuronal cell—cell interactions, between both glia and mast cells and glia themselves, are an integral part of the inflammation process. Within this context the mast cell occupies a key niche in orchestrating the inflammatory process, from initiation to prolongation. This review will describe the current state of knowledge concerning the biology of neuroinflammation, emphasizing mast cell-glia and glia-glia interactions, then conclude with a consideration of how a cell's endogenous mechanisms might be leveraged to provide a therapeutic strategy to target neuroinflammation.
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Affiliation(s)
- Stephen D Skaper
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
| | - Laura Facci
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
| | - Morena Zusso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
| | - Pietro Giusti
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
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325
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Abstract
Growing evidence highlights the crucial physiological functions of microglia that rely on their phagocytic activities, which can be compromised with age. A new study reports the impaired clearance of myelin debris by microglia in the brain, leading to insoluble lysosomal inclusions and contributing to the immune dysfunction and senescence of these cells.
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Affiliation(s)
- Peter Thériault
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, 2705 Laurier boul., Québec City, QC G1V 4G2, Canada
| | - Serge Rivest
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, 2705 Laurier boul., Québec City, QC G1V 4G2, Canada.
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326
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Lifelong cortical myelin plasticity and age-related degeneration in the live mammalian brain. Nat Neurosci 2018; 21:683-695. [PMID: 29556031 PMCID: PMC5920745 DOI: 10.1038/s41593-018-0120-6] [Citation(s) in RCA: 271] [Impact Index Per Article: 45.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 02/05/2018] [Indexed: 01/30/2023]
Abstract
Axonal myelin increases neural processing speed and efficiency. It is unknown whether patterns of myelin distribution are fixed or whether myelinating oligodendrocytes are continually generated in adulthood and maintain the capacity for structural remodeling. Using high-resolution, intravital label-free and fluorescence optical imaging in mouse cortex, we demonstrate lifelong oligodendrocyte generation occurring in parallel with structural plasticity of individual myelin internodes. Continuous internode formation occurred on both partially myelinated and unmyelinated axons, and the total myelin coverage along individual axons progressed up to two years of age. After peak myelination, gradual oligodendrocyte death and myelin degeneration in aging were associated with pronounced internode loss and myelin debris accumulation within microglia. Thus, cortical myelin remodeling is protracted throughout life, potentially playing critical roles in neuronal network homeostasis. The gradual loss of internodes and myelin degeneration in aging could contribute significantly to brain pathogenesis.
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327
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Chen H, Kankel MW, Su SC, Han SWS, Ofengeim D. Exploring the genetics and non-cell autonomous mechanisms underlying ALS/FTLD. Cell Death Differ 2018; 25:648-662. [PMID: 29459769 DOI: 10.1038/s41418-018-0060-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 11/27/2017] [Accepted: 11/28/2017] [Indexed: 12/11/2022] Open
Abstract
Although amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, was first described in 1874, a flurry of genetic discoveries in the last 10 years has markedly increased our understanding of this disease. These findings have not only enhanced our knowledge of mechanisms leading to ALS, but also have revealed that ALS shares many genetic causes with another neurodegenerative disease, frontotemporal lobar dementia (FTLD). In this review, we survey how recent genetic studies have bridged our mechanistic understanding of these two related diseases and how the genetics behind ALS and FTLD point to complex disorders, implicating non-neuronal cell types in disease pathophysiology. The involvement of non-neuronal cell types is consistent with a non-cell autonomous component in these diseases. This is further supported by studies that identified a critical role of immune-associated genes within ALS/FTLD and other neurodegenerative disorders. The molecular functions of these genes support an emerging concept that various non-autonomous functions are involved in neurodegeneration. Further insights into such a mechanism(s) will ultimately lead to a better understanding of potential routes of therapeutic intervention. Facts ALS and FTLD are severe neurodegenerative disorders on the same disease spectrum. Multiple cellular processes including dysregulation of RNA homeostasis, imbalance of proteostasis, contribute to ALS/FTLD pathogenesis. Aberrant function in non-neuronal cell types, including microglia, contributes to ALS/FTLD. Strong neuroimmune and neuroinflammatory components are associated with ALS/FTLD patients. Open Questions Why can patients with similar mutations have different disease manifestations, i.e., why do C9ORF72 mutations lead to motor neuron loss in some patients while others exhibit loss of neurons in the frontotemporal lobe? Do ALS causal mutations result in microglial dysfunction and contribute to ALS/FTLD pathology? How do microglia normally act to mitigate neurodegeneration in ALS/FTLD? To what extent do cellular signaling pathways mediate non-cell autonomous communications between distinct central nervous system (CNS) cell types during disease? Is it possible to therapeutically target specific cell types in the CNS?
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Affiliation(s)
- Hongbo Chen
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Mark W Kankel
- Biogen Inc., 225 Binney Street, Cambridge, MA, 02142, USA
| | - Susan C Su
- Biogen Inc., 225 Binney Street, Cambridge, MA, 02142, USA
| | - Steve W S Han
- Biogen Inc., 225 Binney Street, Cambridge, MA, 02142, USA.,Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,GSK, Upper Providence, PA, 19426, USA
| | - Dimitry Ofengeim
- Biogen Inc., 225 Binney Street, Cambridge, MA, 02142, USA. .,Sanofi Neuroscience, Framingham, MA, USA.
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328
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Moore TL, Bowley BGE, Shultz PL, Calderazzo SM, Shobin EJ, Uprety AR, Rosene DL, Moss MB. Oral curcumin supplementation improves fine motor function in the middle-aged rhesus monkey. Somatosens Mot Res 2018; 35:1-10. [PMID: 29447046 DOI: 10.1080/08990220.2018.1432481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Aged individuals experience decreased fine motor function of the hand and digits, which could result, in part, from the chronic, systemic state of inflammation that occurs with aging. Recent research for treating age-related inflammation has focused on the effects of nutraceuticals that have anti-inflammatory properties. One particular dietary polyphenol, curcumin, the principal curcuminoid of the spice turmeric, has been shown to have significant anti-inflammatory effects and there is mounting evidence that curcumin may serve to reduce systemic inflammation. Therefore, it could be useful for alleviating age-related impairments in fine motor function. To test this hypothesis we assessed the efficacy of a dietary intervention with a commercially available optimized curcumin to ameliorate or delay the effects of aging on fine motor function of the hand of rhesus monkeys. We administered oral daily doses of curcumin or a control vehicle to 11 monkeys over a 14- to 18-month period in which they completed two rounds of fine motor function testing. The monkeys receiving curcumin were significantly faster at retrieving a food reward by round 2 of testing than monkeys receiving a control vehicle. Further, the monkeys receiving curcumin demonstrated a greater degree of improvement in performance on our fine motor task by round 2 of testing than monkeys receiving a control vehicle. These findings reveal that fine motor function of the hand and digits is improved in middle-aged monkeys receiving chronic daily administration of curcumin.
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Affiliation(s)
- Tara L Moore
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA.,b Department of Neurology , Boston University School of Medicine , Boston , MA , USA
| | - Bethany G E Bowley
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA
| | - Penny L Shultz
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA
| | - Samantha M Calderazzo
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA
| | - Eli J Shobin
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA.,c Graduate Program in Neuroscience , Boston University School of Medicine , Boston , MA , USA
| | - Ajay R Uprety
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA
| | - Douglas L Rosene
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA.,d Yerkes National Primate Research Center , Emory University , Atlanta , GA , USA
| | - Mark B Moss
- a Department of Anatomy & Neurobiology , Boston University School of Medicine , Boston , MA , USA.,b Department of Neurology , Boston University School of Medicine , Boston , MA , USA.,d Yerkes National Primate Research Center , Emory University , Atlanta , GA , USA
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329
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Cantuti-Castelvetri L, Fitzner D, Bosch-Queralt M, Weil MT, Su M, Sen P, Ruhwedel T, Mitkovski M, Trendelenburg G, Lütjohann D, Möbius W, Simons M. Defective cholesterol clearance limits remyelination in the aged central nervous system. Science 2018; 359:684-688. [PMID: 29301957 DOI: 10.1126/science.aan4183] [Citation(s) in RCA: 339] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 11/05/2017] [Accepted: 12/11/2017] [Indexed: 11/02/2022]
Abstract
Age-associated decline in regeneration capacity limits the restoration of nervous system functionality after injury. In a model for demyelination, we found that old mice fail to resolve the inflammatory response initiated after myelin damage. Aged phagocytes accumulated excessive amounts of myelin debris, which triggered cholesterol crystal formation and phagolysosomal membrane rupture and stimulated inflammasomes. Myelin debris clearance required cholesterol transporters, including apolipoprotein E. Stimulation of reverse cholesterol transport was sufficient to restore the capacity of old mice to remyelinate lesioned tissue. Thus, cholesterol-rich myelin debris can overwhelm the efflux capacity of phagocytes, resulting in a phase transition of cholesterol into crystals and thereby inducing a maladaptive immune response that impedes tissue regeneration.
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Affiliation(s)
- Ludovico Cantuti-Castelvetri
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Institute of Neuronal Cell Biology, Technical University Munich, 80805 Munich, Germany
- German Center for Neurodegenerative Disease (DZNE), 81377 Munich, Germany
| | - Dirk Fitzner
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
- Department of Neurology, University of Göttingen Medical Center, 37075 Göttingen, Germany
| | - Mar Bosch-Queralt
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Institute of Neuronal Cell Biology, Technical University Munich, 80805 Munich, Germany
- German Center for Neurodegenerative Disease (DZNE), 81377 Munich, Germany
| | - Marie-Theres Weil
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37075 Göttingen, Germany
| | - Minhui Su
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Institute of Neuronal Cell Biology, Technical University Munich, 80805 Munich, Germany
- German Center for Neurodegenerative Disease (DZNE), 81377 Munich, Germany
| | - Paromita Sen
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Torben Ruhwedel
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Miso Mitkovski
- Light Microscopy Facility, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - George Trendelenburg
- Department of Neurology, University of Göttingen Medical Center, 37075 Göttingen, Germany
| | - Dieter Lütjohann
- Institute for Clinical Chemistry and Clinical Pharmacology, University of Bonn, 53127 Bonn, Germany
| | - Wiebke Möbius
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37075 Göttingen, Germany
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Mikael Simons
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Institute of Neuronal Cell Biology, Technical University Munich, 80805 Munich, Germany
- German Center for Neurodegenerative Disease (DZNE), 81377 Munich, Germany
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330
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Abstract
The decline of cognitive function occurs with aging, but the mechanisms responsible are unknown. Astrocytes instruct the formation, maturation, and elimination of synapses, and impairment of these functions has been implicated in many diseases. These findings raise the question of whether astrocyte dysfunction could contribute to cognitive decline in aging. We used the Bac-Trap method to perform RNA sequencing of astrocytes from different brain regions across the lifespan of the mouse. We found that astrocytes have region-specific transcriptional identities that change with age in a region-dependent manner. We validated our findings using fluorescence in situ hybridization and quantitative PCR. Detailed analysis of the differentially expressed genes in aging revealed that aged astrocytes take on a reactive phenotype of neuroinflammatory A1-like reactive astrocytes. Hippocampal and striatal astrocytes up-regulated a greater number of reactive astrocyte genes compared with cortical astrocytes. Moreover, aged brains formed many more A1 reactive astrocytes in response to the neuroinflammation inducer lipopolysaccharide. We found that the aging-induced up-regulation of reactive astrocyte genes was significantly reduced in mice lacking the microglial-secreted cytokines (IL-1α, TNF, and C1q) known to induce A1 reactive astrocyte formation, indicating that microglia promote astrocyte activation in aging. Since A1 reactive astrocytes lose the ability to carry out their normal functions, produce complement components, and release a toxic factor which kills neurons and oligodendrocytes, the aging-induced up-regulation of reactive genes by astrocytes could contribute to the cognitive decline in vulnerable brain regions in normal aging and contribute to the greater vulnerability of the aged brain to injury.
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331
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Mrdjen D, Pavlovic A, Hartmann FJ, Schreiner B, Utz SG, Leung BP, Lelios I, Heppner FL, Kipnis J, Merkler D, Greter M, Becher B. High-Dimensional Single-Cell Mapping of Central Nervous System Immune Cells Reveals Distinct Myeloid Subsets in Health, Aging, and Disease. Immunity 2018; 48:380-395.e6. [DOI: 10.1016/j.immuni.2018.01.011] [Citation(s) in RCA: 311] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/05/2017] [Accepted: 01/14/2018] [Indexed: 12/14/2022]
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332
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d’Avila JC, Siqueira LD, Mazeraud A, Azevedo EP, Foguel D, Castro-Faria-Neto HC, Sharshar T, Chrétien F, Bozza FA. Age-related cognitive impairment is associated with long-term neuroinflammation and oxidative stress in a mouse model of episodic systemic inflammation. J Neuroinflammation 2018; 15:28. [PMID: 29382344 PMCID: PMC5791311 DOI: 10.1186/s12974-018-1059-y] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 01/08/2018] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Microglia function is essential to maintain the brain homeostasis. Evidence shows that aged microglia are primed and show exaggerated response to acute inflammatory challenge. Systemic inflammation signals to the brain inducing changes that impact cognitive function. However, the mechanisms involved in age-related cognitive decline associated to episodic systemic inflammation are not completely understood. The aim of this study was to identify neuropathological features associated to age-related cognitive decline in a mouse model of episodic systemic inflammation. METHODS Young and aged Swiss mice were injected with low doses of LPS once a week for 6 weeks to induce episodic systemic inflammation. Sickness behavior, inflammatory markers, and neuroinflammation were assessed in different phases of systemic inflammation in young and aged mice. Behavior was evaluated long term after episodic systemic inflammation by open field, forced swimming, object recognition, and water maze tests. RESULTS Episodic systemic inflammation induced systemic inflammation and sickness behavior mainly in aged mice. Systemic inflammation induced depressive-like behavior in both young and aged mice. Memory and learning were significantly affected in aged mice that presented lower exploratory activity and deficits in episodic and spatial memories, compared to aged controls and to young after episodic systemic inflammation. Systemic inflammation induced acute microglia activation in young mice that returned to base levels long term after episodic systemic inflammation. Aged mice presented dystrophic microglia in the hippocampus and entorhinal cortex at basal level and did not change morphology in the acute response to SI. Regardless of their dystrophic microglia, aged mice produced higher levels of pro-inflammatory (IL-1β and IL-6) as well as pro-resolution (IL-10 and IL-4) cytokines in the brain. Also, higher levels of Nox2 expression, oxidized proteins and lower antioxidant defenses were found in the aged brains compared to the young after episodic systemic inflammation. CONCLUSIONS Our data show that aged mice have increased susceptibility to episodic systemic inflammation. Aged mice that showed cognitive impairments also presented higher oxidative stress and abnormal production of cytokines in their brains. These results indicate that a neuroinflammation and oxidative stress are pathophysiological mechanisms of age-related cognitive impairments.
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Affiliation(s)
- Joana Costa d’Avila
- Laboratory of Immunopharmacology, Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Luciana Domett Siqueira
- Institute of Medical Biochemistry Leopoldo DeMeis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Aurélien Mazeraud
- Human Histopathology and Animal Models, Pasteur Institute, Paris, France
| | - Estefania Pereira Azevedo
- Institute of Medical Biochemistry Leopoldo DeMeis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Debora Foguel
- Institute of Medical Biochemistry Leopoldo DeMeis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Tarek Sharshar
- Human Histopathology and Animal Models, Pasteur Institute, Paris, France
| | - Fabrice Chrétien
- Human Histopathology and Animal Models, Pasteur Institute, Paris, France
| | - Fernando Augusto Bozza
- National Institute of Infectious Diseases Evandro Chagas, Oswaldo Cruz Foundation (FIOCRUZ), Ministry of Health, Rio de Janeiro, Brazil
- D’Or Institute for Research and Education (IDOR), Rio de Janeiro, Brazil
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333
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Bergholt MS, Serio A, McKenzie JS, Boyd A, Soares RF, Tillner J, Chiappini C, Wu V, Dannhorn A, Takats Z, Williams A, Stevens MM. Correlated Heterospectral Lipidomics for Biomolecular Profiling of Remyelination in Multiple Sclerosis. ACS CENTRAL SCIENCE 2018; 4:39-51. [PMID: 29392175 PMCID: PMC5785772 DOI: 10.1021/acscentsci.7b00367] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Indexed: 05/22/2023]
Abstract
Analyzing lipid composition and distribution within the brain is important to study white matter pathologies that present focal demyelination lesions, such as multiple sclerosis. Some lesions can endogenously re-form myelin sheaths. Therapies aim to enhance this repair process in order to reduce neurodegeneration and disability progression in patients. In this context, a lipidomic analysis providing both precise molecular classification and well-defined localization is crucial to detect changes in myelin lipid content. Here we develop a correlated heterospectral lipidomic (HSL) approach based on coregistered Raman spectroscopy, desorption electrospray ionization mass spectrometry (DESI-MS), and immunofluorescence imaging. We employ HSL to study the structural and compositional lipid profile of demyelination and remyelination in an induced focal demyelination mouse model and in multiple sclerosis lesions from patients ex vivo. Pixelwise coregistration of Raman spectroscopy and DESI-MS imaging generated a heterospectral map used to interrelate biomolecular structure and composition of myelin. Multivariate regression analysis enabled Raman-based assessment of highly specific lipid subtypes in complex tissue for the first time. This method revealed the temporal dynamics of remyelination and provided the first indication that newly formed myelin has a different lipid composition compared to normal myelin. HSL enables detailed molecular myelin characterization that can substantially improve upon the current understanding of remyelination in multiple sclerosis and provides a strategy to assess remyelination treatments in animal models.
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Affiliation(s)
- Mads S. Bergholt
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
- Institute
of Biomedical Engineering, Imperial College
London, London SW7 2AZ, United Kingdom
| | - Andrea Serio
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
- Institute
of Biomedical Engineering, Imperial College
London, London SW7 2AZ, United Kingdom
| | - James S. McKenzie
- Computational
and Systems Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Amanda Boyd
- MRC
Centre for Regenerative Medicine, University
of Edinburgh, Edinburgh EH16 4UU, United Kingdom
| | - Renata F. Soares
- Computational
and Systems Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jocelyn Tillner
- Computational
and Systems Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Ciro Chiappini
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
- Institute
of Biomedical Engineering, Imperial College
London, London SW7 2AZ, United Kingdom
| | - Vincen Wu
- Computational
and Systems Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Andreas Dannhorn
- Computational
and Systems Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Zoltan Takats
- Computational
and Systems Medicine, Imperial College London, London SW7 2AZ, United Kingdom
| | - Anna Williams
- MRC
Centre for Regenerative Medicine, University
of Edinburgh, Edinburgh EH16 4UU, United Kingdom
| | - Molly M. Stevens
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
- Institute
of Biomedical Engineering, Imperial College
London, London SW7 2AZ, United Kingdom
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334
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Bove RM. Why monkeys do not get multiple sclerosis (spontaneously): An evolutionary approach. EVOLUTION MEDICINE AND PUBLIC HEALTH 2018; 2018:43-59. [PMID: 29492266 PMCID: PMC5824939 DOI: 10.1093/emph/eoy002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/07/2017] [Indexed: 12/20/2022]
Abstract
The goal of this review is to apply an evolutionary lens to understanding the origins of multiple sclerosis (MS), integrating three broad observations. First, only humans are known to develop MS spontaneously. Second, humans have evolved large brains, with characteristically large amounts of metabolically costly myelin. This myelin is generated over long periods of neurologic development—and peak MS onset coincides with the end of myelination. Third, over the past century there has been a disproportionate increase in the rate of MS in young women of childbearing age, paralleling increasing westernization and urbanization, indicating sexually specific susceptibility in response to changing exposures. From these three observations about MS, a life history approach leads us to hypothesize that MS arises in humans from disruption of the normal homeostatic mechanisms of myelin production and maintenance, during our uniquely long myelination period. This review will highlight under-explored areas of homeostasis in brain development, that are likely to shed new light on the origins of MS and to raise further questions about the interactions between our ancestral genes and modern environments.
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Affiliation(s)
- Riley M Bove
- Department of Neurology, UCSF, San Francisco, CA, USA
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335
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Deficient Surveillance and Phagocytic Activity of Myeloid Cells Within Demyelinated Lesions in Aging Mice Visualized by Ex Vivo Live Multiphoton Imaging. J Neurosci 2018; 38:1973-1988. [PMID: 29363580 DOI: 10.1523/jneurosci.2341-17.2018] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/22/2017] [Accepted: 01/12/2018] [Indexed: 12/17/2022] Open
Abstract
Aging impairs regenerative processes including remyelination, the synthesis of a new myelin sheath. Microglia and other infiltrating myeloid cells such as macrophages are essential for remyelination through mechanisms that include the clearance of inhibitory molecules within the lesion. Prior studies have shown that the quantity of myeloid cells and the clearance of inhibitory myelin debris are deficient in aging, contributing to the decline in remyelination efficiency with senescence. It is unknown, however, whether the impaired clearance of debris is simply the result of the reduced number of phagocytes or if the dynamic activity of myeloid cells within the demyelinating plaque also declines with aging and this question is relevant to the proper design of therapeutics to mobilize myeloid cells for repair. Herein, we describe a high-resolution multiphoton ex vivo live imaging protocol that visualizes individual myelinated/demyelinated axons and lipid-containing myeloid cells to investigate the demyelinated lesion of aging female mice. We found that aging lesions have fewer myeloid cells and that these have reduced phagocytosis of myelin. Although the myeloid cells are actively migratory within the lesion of young mice and have protrusions that seem to survey the environment, this motility and surveillance is significantly reduced in aging mice. Our results emphasize the necessity of not only increasing the number of phagocytes, but also enhancing their activity once they are within demyelinated lesions. The high-resolution live imaging of demyelinated lesions can serve as a platform with which to discover pharmacological agents that rejuvenate intralesional remodeling that promotes the repair of plaques.SIGNIFICANCE STATEMENT The repair of myelin after injury depends on myeloid cells that clear debris and release growth factors. As organisms age, remyelination becomes less efficient correspondent with fewer myeloid cells that populate the lesions. It is unknown whether the dynamic activity of cells within lesions is also altered with age. Herein, using high-resolution multiphoton ex vivo live imaging with several novel features, we report that myeloid cells within demyelinated lesions of aging mice have reduced motility, surveillance, and phagocytic activity, suggesting an intralesional impairment that may contribute to the age-related decline in remyelination efficiency. Medications to stimulate deficient aging myeloid cells should not only increase their representation, but also enter into lesions to stimulate their activity.
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336
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Mixed Neurodevelopmental and Neurodegenerative Pathology in Nhe6-Null Mouse Model of Christianson Syndrome. eNeuro 2018; 4:eN-NWR-0388-17. [PMID: 29349289 PMCID: PMC5771691 DOI: 10.1523/eneuro.0388-17.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/12/2017] [Accepted: 12/17/2017] [Indexed: 12/20/2022] Open
Abstract
Christianson syndrome (CS) is an X-linked disorder resulting from loss-of-function mutations in SLC9A6, which encodes the endosomal Na+/H+ exchanger 6 (NHE6). Symptoms include early developmental delay, seizures, intellectual disability, nonverbal status, autistic features, postnatal microcephaly, and progressive ataxia. Neuronal development is impaired in CS, involving defects in neuronal arborization and synaptogenesis, likely underlying diminished brain growth postnatally. In addition to neurodevelopmental defects, some reports have supported neurodegenerative pathology in CS with age. The objective of this study was to determine the nature of progressive changes in the postnatal brain in Nhe6-null mice. We examined the trajectories of brain growth and atrophy in mutant mice from birth until very old age (2 yr). We report trajectories of volume changes in the mutant that likely reflect both brain undergrowth as well as tissue loss. Reductions in volume are first apparent at 2 mo, particularly in the cerebellum, which demonstrates progressive loss of Purkinje cells (PCs). We report PC loss in two distinct Nhe6-null mouse models. More widespread reductions in tissue volumes, namely, in the hippocampus, striatum, and cortex, become apparent after 2 mo, largely reflecting delays in growth with more limited tissue losses with aging. Also, we identify pronounced glial responses, particularly in major fiber tracts such as the corpus callosum, where the density of activated astrocytes and microglia are substantially increased. The prominence of the glial response in axonal tracts suggests a primary axonopathy. Importantly, therefore, our data support both neurodevelopmental and degenerative mechanisms in the pathobiology of CS.
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337
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DNA damage-associated oligodendrocyte degeneration precedes amyloid pathology and contributes to Alzheimer's disease and dementia. Alzheimers Dement 2018; 14:664-679. [PMID: 29328926 DOI: 10.1016/j.jalz.2017.11.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/18/2017] [Accepted: 11/28/2017] [Indexed: 11/20/2022]
Abstract
INTRODUCTION In looking for novel non-amyloid-based etiologies for Alzheimer's disease, we explore the hypothesis that age-related myelin loss is an attractive explanation for age-associated cognitive decline and dementia. METHODS We performed a meta-analysis of data in the National Alzheimer's Coordinating Center database accompanied by quantitative histopathology of myelin and oligodendrocytes (OLs) in frontal cortices of 24 clinically characterized individuals. Pathological findings were further validated in an Alzheimer's disease mouse model and in culture. RESULTS Myelin lesions increased with cognitive impairment in an amyloid-independent fashion with signs of degeneration appearing before neuronal loss. Myelinating OLs in the gray matter showed greater vulnerability than those in white matter, and the degenerative changes correlated with evidence of DNA damage. Similar results were found in myelinating OL cultures where DNA damage caused aberrant OL cell cycle re-entry and death. DISCUSSION We present the first comprehensive analysis of the cell biology of early myelin loss in sporadic Alzheimer's disease.
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338
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Scott-Hewitt NJ, Folts CJ, Noble MD. Heterozygous carriers of galactocerebrosidase mutations that cause Krabbe disease have impaired microglial function and defective repair of myelin damage. Neural Regen Res 2018; 13:393-401. [PMID: 29623914 PMCID: PMC5900492 DOI: 10.4103/1673-5374.228712] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This review addresses two puzzling findings related to mutations in galactocerebrosidase (GALC) that cause Krabbe disease (KD), a severe lysosomal storage disorder characterized by extensive myelin damage in children with mutations in both GALC alleles. First, heterozygous carriers of KD-causing mutations, which include the biological parents of children with KD, exhibit increased risk for developing other diseases. Second, variants in the GALC locus increase the risk of developing multiple sclerosis (MS), another disease characterized by extensive myelin damage. What explains these correlations? In studies on cuprizone-induced myelin damage in heterozygous (GALC+/–) mice carrying one copy of a mutation that causes KD-like disease, the extent of damage was similar in GALC+/– and wild-type (WT) mice. In contrast, GALC+/- mice had striking defects in repair of cuprizone-induced damage. We further found unexpected microglial defects in myelin debris clearance and in the ability to up-regulate the Trem2 microglial protein critical for debris uptake. These defects were rescued by exposure to a lysosomal re-acidifying drug discovered in our studies on KD, and which provides multiple clinically relevant benefits in the twitcher (GALC+/–) mouse model of KD. Thus, heterozygous GALC mutations cause effects on biological function that may help to understand the increased disease risk in heterozygous carriers of such mutations and to understand why GALC variations increase the risk of MS. Our findings indicate that while some genetic risk factors may contribute to complex diseases by increasing the risk of tissue damage, others may do so by compromising tissue repair.
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Affiliation(s)
- Nicole J Scott-Hewitt
- Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Christopher J Folts
- Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Mark D Noble
- Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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339
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Clayton KA, Van Enoo AA, Ikezu T. Alzheimer's Disease: The Role of Microglia in Brain Homeostasis and Proteopathy. Front Neurosci 2017; 11:680. [PMID: 29311768 PMCID: PMC5733046 DOI: 10.3389/fnins.2017.00680] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/21/2017] [Indexed: 01/15/2023] Open
Abstract
Brain aging is central to late-onset Alzheimer's disease (LOAD), although the mechanisms by which it occurs at protein or cellular levels are not fully understood. Alzheimer's disease is the most common proteopathy and is characterized by two unique pathologies: senile plaques and neurofibrillary tangles, the former accumulating earlier than the latter. Aging alters the proteostasis of amyloid-β peptides and microtubule-associated protein tau, which are regulated in both autonomous and non-autonomous manners. Microglia, the resident phagocytes of the central nervous system, play a major role in the non-autonomous clearance of protein aggregates. Their function is significantly altered by aging and neurodegeneration. This is genetically supported by the association of microglia-specific genes, TREM2 and CD33, and late onset Alzheimer's disease. Here, we propose that the functional characterization of microglia, and their contribution to proteopathy, will lead to a new therapeutic direction in Alzheimer's disease research.
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Affiliation(s)
- Kevin A Clayton
- Department of Pharmacology and Experimental Therapeutics, Medical School, Boston University, Boston, MA, United States
| | - Alicia A Van Enoo
- Department of Pharmacology and Experimental Therapeutics, Medical School, Boston University, Boston, MA, United States
| | - Tsuneya Ikezu
- Department of Pharmacology and Experimental Therapeutics, Medical School, Boston University, Boston, MA, United States.,Department of Neurology, Medical School, Boston University, Boston, MA, United States
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340
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Lannes N, Eppler E, Etemad S, Yotovski P, Filgueira L. Microglia at center stage: a comprehensive review about the versatile and unique residential macrophages of the central nervous system. Oncotarget 2017; 8:114393-114413. [PMID: 29371994 PMCID: PMC5768411 DOI: 10.18632/oncotarget.23106] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/15/2017] [Indexed: 02/07/2023] Open
Abstract
Microglia cells are the unique residential macrophages of the central nervous system (CNS). They have a special origin, as they derive from the embryonic yolk sac and enter the developing CNS at a very early stage. They play an important role during CNS development and adult homeostasis. They have a major contribution to adult neurogenesis and neuroinflammation. Thus, they participate in the pathogenesis of neurodegenerative diseases and contribute to aging. They play an important role in sustaining and breaking the blood-brain barrier. As innate immune cells, they contribute substantially to the immune response against infectious agents affecting the CNS. They play also a major role in the growth of tumours of the CNS. Microglia are consequently the key cell population linking the nervous and the immune system. This review covers all different aspects of microglia biology and pathology in a comprehensive way.
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Affiliation(s)
- Nils Lannes
- Albert Gockel, Anatomy, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Elisabeth Eppler
- Pestalozzistrasse Zo, Department of BioMedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Samar Etemad
- Building 71/218 RBWH Herston, Centre for Clinical Research, The University of Queensland, QLD 4029 Brisbane, Australia
| | - Peter Yotovski
- Albert Gockel, Anatomy, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Luis Filgueira
- Albert Gockel, Anatomy, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
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341
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Moore TL, Bowley B, Shultz P, Calderazzo S, Shobin E, Killiany RJ, Rosene DL, Moss MB. Chronic curcumin treatment improves spatial working memory but not recognition memory in middle-aged rhesus monkeys. GeroScience 2017; 39:571-584. [PMID: 29047012 PMCID: PMC5745216 DOI: 10.1007/s11357-017-9998-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 10/02/2017] [Indexed: 12/15/2022] Open
Abstract
Studies of both humans and non-human primates have demonstrated that aging is typically characterized by a decline in cognition that can occur as early as the fifth decade of life. Age-related changes in working memory are particularly evident and mediated, in part, by the prefrontal cortex, an area known to evidence age-related changes in myelin that is attributed to inflammation. In recent years, several nutraceuticals, including curcumin, by virtue of their anti-inflammatory and antioxidant effects, have received considerable attention as potential treatments for age-related cognitive decline and inflammation. Accordingly, we assessed for the first time in a non-human primate model of normal aging the efficacy of dietary intervention using the natural phenol curcumin to ameliorate the effects of aging on spatial working and recognition memory. Results revealed that monkeys receiving daily administration of curcumin over 14-18 months demonstrated a greater improvement in performance on repeated administration of a task of spatial working memory compared to monkeys that received a control substance.
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Affiliation(s)
- Tara L Moore
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA.
- Department of Neurology, Boston University School of Medicine, 725 Albany Street, Boston, MA, 02118, USA.
| | - Bethany Bowley
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
| | - Penny Shultz
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
| | - Samantha Calderazzo
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
| | - Eli Shobin
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
- Graduate Program in Neuroscience, Boston University School of Medicine, 72 E. Concord Street, Boston, MA, 02118, USA
| | - Ronald J Killiany
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
- Department of Neurology, Boston University School of Medicine, 725 Albany Street, Boston, MA, 02118, USA
| | - Douglas L Rosene
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
- Yerkes National Primate Research Center, Emory University, 201 Dowman Drive, Atlanta, GA, 30322, USA
| | - Mark B Moss
- Department of Anatomy & Neurobiology, Boston University School of Medicine, 72 E. Concord Street, L-1004, Boston, MA, 02118, USA
- Department of Neurology, Boston University School of Medicine, 725 Albany Street, Boston, MA, 02118, USA
- Yerkes National Primate Research Center, Emory University, 201 Dowman Drive, Atlanta, GA, 30322, USA
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342
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Age-related changes in microglial physiology: the role for healthy brain ageing and neurodegenerative disorders. ACTA ACUST UNITED AC 2017. [DOI: 10.1515/nf-2016-a057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Microglia are the main immune cells of the brain contributing, however, not only to brain’s immune defense but also to many basic housekeeping functions such as development and maintenance of functional neural networks, provision of trophic support for surrounding neurons, monitoring and modulating the levels of synaptic activity, cleaning of accumulating extracellular debris and repairing microdamages of the brain parenchyma. As a consequence, age-related alterations in microglial function likely have a manifold impact on brain’s physiology. In this review, I discuss the recent data about physiological properties of microglia in the adult mammalian brain; changes observed in the brain innate immune system during healthy aging and the probable biological mechanisms responsible for them as well as changes occurring in humans and mice during age-related neurodegenerative disorders along with underlying cellular/molecular mechanisms. Together these data provide a new conceptual framework for thinking about the role of microglia in the context of age-mediated brain dysfunction.
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343
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Loss of APOBEC1 RNA-editing function in microglia exacerbates age-related CNS pathophysiology. Proc Natl Acad Sci U S A 2017; 114:13272-13277. [PMID: 29167375 DOI: 10.1073/pnas.1710493114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Microglia (MG), a heterogeneous population of phagocytic cells, play important roles in central nervous system (CNS) homeostasis and neural plasticity. Under steady-state conditions, MG maintain homeostasis by producing antiinflammatory cytokines and neurotrophic factors, support myelin production, and remove synapses and cellular debris, as well as participating in "cross-correction," a process that supplies neurons with key factors for executing autophagy-lysosomal function. As sentinels for the immune system, MG also detect "danger" signals (pathogenic or traumatic insult), become activated, produce proinflammatory cytokines, and recruit monocytes and dendritic cells to the site of damage through a breached blood-brain barrier or via brain lymphatics. Failure to effectively resolve MG activation can be problematic and can lead to chronic inflammation, a condition proposed to underlie CNS pathophysiology in heritable brain disorders and age-related neurodegenerative and cognitive decline. Here, we show that APOBEC1-mediated RNA editing occurs within MG and is key to maintaining their resting status. Like bone marrow-derived macrophages, RNA editing in MG leads to overall changes in the abundance of edited proteins that coordinate the function of multiple cellular pathways. Conversely, mice lacking the APOBEC1 editing function in MG display evidence of dysregulation, with progressive age-related signs of neurodegeneration, characterized by clustering of activated MG, aberrant myelination, increased inflammation, and lysosomal anomalies that culminate in behavioral and motor deficiencies. Collectively, our study identifies posttranscriptional modification by RNA editing as a critical regulatory mechanism of vital cellular functions that maintain overall brain health.
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344
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Abstract
Microglia and non-parenchymal macrophages in the brain are mononuclear phagocytes that are increasingly recognized to be essential players in the development, homeostasis and diseases of the central nervous system. With the availability of new genetic, molecular and pharmacological tools, considerable advances have been made towards our understanding of the embryonic origins, developmental programmes and functions of these cells. These exciting discoveries, some of which are still controversial, also raise many new questions, which makes brain macrophage biology a fast-growing field at the intersection of neuroscience and immunology. Here, we review the current knowledge of how and where brain macrophages are generated, with a focus on parenchymal microglia. We also discuss their normal functions during development and homeostasis, the disturbance of which may lead to various neurodegenerative and neuropsychiatric diseases.
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345
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Cao Y, Wang X, Shi X, Clee SM, McGeer PL, Wolf MO, Orvig C. Biological Imaging with Medium-Sensitive Bichromatic Flexible Fluorescent Dyes. Angew Chem Int Ed Engl 2017; 56:15603-15606. [DOI: 10.1002/anie.201708529] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/10/2017] [Indexed: 01/14/2023]
Affiliation(s)
- Yang Cao
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
| | - Xiaozhu Wang
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
| | - Xiaolei Shi
- The Kinsmen Laboratory of Neurological Research; University of British Columbia; Vancouver British Columbia Canada
| | - Susanne M. Clee
- Canada Research Chair in the Genetics of Obesity and Diabetes, Department of Cellular and Physiological Sciences; University of British Columbia; Vancouver British Columbia Canada
| | - Patrick L. McGeer
- The Kinsmen Laboratory of Neurological Research; University of British Columbia; Vancouver British Columbia Canada
| | - Michael O. Wolf
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
| | - Chris Orvig
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
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346
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Cao Y, Wang X, Shi X, Clee SM, McGeer PL, Wolf MO, Orvig C. Biological Imaging with Medium-Sensitive Bichromatic Flexible Fluorescent Dyes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201708529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Yang Cao
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
| | - Xiaozhu Wang
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
| | - Xiaolei Shi
- The Kinsmen Laboratory of Neurological Research; University of British Columbia; Vancouver British Columbia Canada
| | - Susanne M. Clee
- Canada Research Chair in the Genetics of Obesity and Diabetes, Department of Cellular and Physiological Sciences; University of British Columbia; Vancouver British Columbia Canada
| | - Patrick L. McGeer
- The Kinsmen Laboratory of Neurological Research; University of British Columbia; Vancouver British Columbia Canada
| | - Michael O. Wolf
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
| | - Chris Orvig
- Department of Chemistry; University of British Columbia; Vancouver British Columbia Canada
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347
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Menzel F, Kaiser N, Haehnel S, Rapp F, Patties I, Schöneberg N, Haimon Z, Immig K, Bechmann I. Impact of X-irradiation on microglia. Glia 2017; 66:15-33. [DOI: 10.1002/glia.23239] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 09/05/2017] [Accepted: 09/18/2017] [Indexed: 12/20/2022]
Affiliation(s)
| | - Nicole Kaiser
- Institute of Anatomy, Leipzig University; Leipzig Germany
| | - Susann Haehnel
- Institute of Anatomy, Leipzig University; Leipzig Germany
| | - Felicitas Rapp
- Institute of Anatomy, Leipzig University; Leipzig Germany
| | - Ina Patties
- Department of Radiation Therapy; Leipzig University; Leipzig Germany
| | | | - Zhana Haimon
- Department of Immunology; Weizmann Institute of Science; Rehovot Israel
| | - Kerstin Immig
- Institute of Anatomy, Leipzig University; Leipzig Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University; Leipzig Germany
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348
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Chronic cerebral hypoperfusion: a key mechanism leading to vascular cognitive impairment and dementia. Closing the translational gap between rodent models and human vascular cognitive impairment and dementia. Clin Sci (Lond) 2017; 131:2451-2468. [PMID: 28963120 DOI: 10.1042/cs20160727] [Citation(s) in RCA: 231] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 08/28/2017] [Accepted: 09/04/2017] [Indexed: 12/15/2022]
Abstract
Increasing evidence suggests that vascular risk factors contribute to neurodegeneration, cognitive impairment and dementia. While there is considerable overlap between features of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD), it appears that cerebral hypoperfusion is the common underlying pathophysiological mechanism which is a major contributor to cognitive decline and degenerative processes leading to dementia. Sustained cerebral hypoperfusion is suggested to be the cause of white matter attenuation, a key feature common to both AD and dementia associated with cerebral small vessel disease (SVD). White matter changes increase the risk for stroke, dementia and disability. A major gap has been the lack of mechanistic insights into the evolution and progress of VCID. However, this gap is closing with the recent refinement of rodent models which replicate chronic cerebral hypoperfusion. In this review, we discuss the relevance and advantages of these models in elucidating the pathogenesis of VCID and explore the interplay between hypoperfusion and the deposition of amyloid β (Aβ) protein, as it relates to AD. We use examples of our recent investigations to illustrate the utility of the model in preclinical testing of candidate drugs and lifestyle factors. We propose that the use of such models is necessary for tackling the urgently needed translational gap from preclinical models to clinical treatments.
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349
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Schwann cells use TAM receptor-mediated phagocytosis in addition to autophagy to clear myelin in a mouse model of nerve injury. Proc Natl Acad Sci U S A 2017; 114:E8072-E8080. [PMID: 28874532 DOI: 10.1073/pnas.1710566114] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ineffective myelin debris clearance is a major factor contributing to the poor regenerative ability of the central nervous system. In stark contrast, rapid clearance of myelin debris from the injured peripheral nervous system (PNS) is one of the keys to this system's remarkable regenerative capacity, but the molecular mechanisms driving PNS myelin clearance are incompletely understood. We set out to discover new pathways of PNS myelin clearance to identify novel strategies for activating myelin clearance in the injured central nervous system, where myelin debris is not cleared efficiently. Here we show that Schwann cells, the myelinating glia of the PNS, collaborate with hematogenous macrophages to clear myelin debris using TAM (Tyro3, Axl, Mer) receptor-mediated phagocytosis as well as autophagy. In a mouse model of PNS nerve crush injury, Schwann cells up-regulate TAM phagocytic receptors Axl and Mertk following PNS injury, and Schwann cells lacking both of these phagocytic receptors exhibit significantly impaired myelin phagocytosis both in vitro and in vivo. Autophagy-deficient Schwann cells also display reductions in myelin clearance after mouse nerve crush injury, as has been recently shown following nerve transection. These findings add a mechanism, Axl/Mertk-mediated myelin clearance, to the repertoire of cellular machinery used to clear myelin in the injured PNS. Given recent evidence that astrocytes express Axl and Mertk and have previously unrecognized phagocytic potential, this pathway may be a promising avenue for activating myelin clearance after CNS injury.
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350
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Varela-Echevarría A, Vargas-Barroso V, Lozano-Flores C, Larriva-Sahd J. Is There Evidence for Myelin Modeling by Astrocytes in the Normal Adult Brain? Front Neuroanat 2017; 11:75. [PMID: 28932188 PMCID: PMC5592641 DOI: 10.3389/fnana.2017.00075] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 08/15/2017] [Indexed: 11/13/2022] Open
Abstract
A set of astrocytic process associated with altered myelinated axons is described in the forebrain of normal adult rodents with confocal, electron microscopy, and 3D reconstructions. Each process consists of a protuberance that contains secretory organelles including numerous lysosomes which polarize and open next to disrupted myelinated axons. Because of the distinctive asymmetric organelle distribution and ubiquity throughout the forebrain neuropil, this enlargement is named paraxial process (PAP). The myelin envelope contiguous to the PAP displays focal disruption or disintegration. In routine electron microscopy clusters of large, confluent, lysosomes proved to be an effective landmark for PAP identification. In 3D assemblies lysosomes organize a series of interconnected saccules that open up to the plasmalemma next to the disrupted myelin envelope(s). Activity for acid hydrolases was visualized in lysosomes, and extracellularly at the PAP-myelin interface and/or between the glial and neuronal outer aspects. Organelles in astrocytic processes involved in digesting pyknotic cells and debris resemble those encountered in PAPs supporting a likewise lytic function of the later. Conversely, processes entangling tripartite synapses and glomeruli were devoid of lysosomes. Both oligodendrocytic and microglial processes were not associated with altered myelin envelopes. The possible roles of the PAP in myelin remodeling in the context of the oligodendrocyte-astrocyte interactions and in the astrocyte's secretory pathways are discussed.
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Affiliation(s)
- Alfredo Varela-Echevarría
- Department of Developmental Biology and Neurophysiology, Instituto de Neurobiología Universidad Nacional Autónoma de MéxicoQuerétaro, Mexico
| | - Víctor Vargas-Barroso
- Department of Developmental Biology and Neurophysiology, Instituto de Neurobiología Universidad Nacional Autónoma de MéxicoQuerétaro, Mexico
| | - Carlos Lozano-Flores
- Department of Developmental Biology and Neurophysiology, Instituto de Neurobiología Universidad Nacional Autónoma de MéxicoQuerétaro, Mexico
| | - Jorge Larriva-Sahd
- Department of Developmental Biology and Neurophysiology, Instituto de Neurobiología Universidad Nacional Autónoma de MéxicoQuerétaro, Mexico
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