151
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Guo F, Zhang YF, Liu K, Huang X, Li RX, Wang SY, Wang F, Xiao L, Mei F, Li T. Chronic Exposure to Alcohol Inhibits New Myelin Generation in Adult Mouse Brain. Front Cell Neurosci 2021; 15:732602. [PMID: 34512271 PMCID: PMC8429601 DOI: 10.3389/fncel.2021.732602] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/10/2021] [Indexed: 12/01/2022] Open
Abstract
Chronic alcohol consumption causes cognitive impairments accompanying with white matter atrophy. Recent evidence has shown that myelin dynamics remain active and are important for brain functions in adulthood. For example, new myelin generation is required for learning and memory functions. However, it remains undetermined whether alcohol exposure can alter myelin dynamics in adulthood. In this study, we examine the effect of chronic alcohol exposure on myelin dynamics by using genetic approaches to label newly generated myelin (NG2-CreERt; mT/mG). Our results indicated that alcohol exposure (either 5% or 10% in drinking water) for 3 weeks remarkably reduced mGFP + /NG2- new myelin and mGFP + /CC1 + new oligodendrocytes in the prefrontal cortex and corpus callosum of 6-month-old NG2-CreERt; mT/mG mice as compared to controls without changing the mGFP + /NG2 + oligodendrocyte precursor cells (OPCs) density, suggesting that alcohol exposure may inhibit oligodendrocyte differentiation. In support with these findings, the alcohol exposure did not significantly alter apoptotic cell number or overall MBP expression in the brains. Further, the alcohol exposure decreased the histone deacetylase1 (HDAC1) expression in mGFP + /NG2 + OPCs, implying epigenetic mechanisms were involved in the arrested OPC differentiation. Together, our results indicate that chronic exposure to alcohol can inhibit myelinogenesis in the adult mouse brain and that may contribute to alcohol-related cognitive impairments.
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Affiliation(s)
- Feng Guo
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China.,The First Camp of Cadet Brigade, School of Basic Medicine, Third Military Medical University (Army Medical University), Chongqing, China
| | - Yi-Fan Zhang
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China.,The First Camp of Cadet Brigade, School of Basic Medicine, Third Military Medical University (Army Medical University), Chongqing, China
| | - Kun Liu
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Xu Huang
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Rui-Xue Li
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Shu-Yue Wang
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Fei Wang
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Lan Xiao
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Feng Mei
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Tao Li
- Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Department of Histology and Embryology, Third Military Medical University (Army Medical University), Chongqing, China
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152
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Sanchez-Molina P, Almolda B, Benseny-Cases N, González B, Perálvarez-Marín A, Castellano B. Specific microglial phagocytic phenotype and decrease of lipid oxidation in white matter areas during aging: Implications of different microenvironments. Neurobiol Aging 2021; 105:280-295. [PMID: 34139605 DOI: 10.1016/j.neurobiolaging.2021.03.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 03/25/2021] [Accepted: 03/28/2021] [Indexed: 12/25/2022]
Abstract
Physiological aging is characterized by an imbalance of pro-inflammatory and anti-inflammatory mediators leading to neuroinflammation. Microglial cells, which are highly regulated by the local microenvironment, undergo specific changes depending upon the brain area during aging. The aim of this study was to evaluate the influence of age over microglial cells along different brain areas and microenvironments. For this purpose, transgenic mice with overproduction of either the anti-inflammatory IL-10 cytokine or the pro-inflammatory IL-6 cytokine were used. Our results show that, during aging, microglial cells located in white matter (WM) areas maintain their phagocytic capacity but present a specific phagocytic phenotype with receptors involved in myelin recognition, arguing for aging-derived myelin damage. Whereas IL-10 overproduction anticipates the age-related microglial phagocytic phenotype, maintaining it over time, IL-6 overproduction exacerbates this phenotype in aging. These modifications were linked with a higher efficiency of myelin engulfment by microglia in aged transgenic animals. Moreover, we show, in a novel way, lower lipid oxidation during aging in WM areas, regardless of the genotype. The novelty of the insights presented in this study open a window to deeply investigate myelin lipid oxidation and the role of microglial cells in its regulation during physiological aging.
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Affiliation(s)
- Paula Sanchez-Molina
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Beatriz Almolda
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
| | - Núria Benseny-Cases
- ALBA Synchrotron Light Source, Carrer de la Llum 2-26, Cerdanyola del Vallès, Catalonia, Spain
| | - Berta González
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Alex Perálvarez-Marín
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Biochemistry and Molecular Biology. Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain
| | - Bernardo Castellano
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
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153
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Sams E. Oligodendrocytes in the aging brain. Neuronal Signal 2021; 5:NS20210008. [PMID: 34290887 PMCID: PMC8264650 DOI: 10.1042/ns20210008] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 12/22/2022] Open
Abstract
More than half of the human brain volume is made up of white matter: regions where axons are coated in myelin, which primarily functions to increase the conduction speed of axon potentials. White matter volume significantly decreases with age, correlating with cognitive decline. Much research in the field of non-pathological brain aging mechanisms has taken a neuron-centric approach, with relatively little attention paid to other neural cells. This review discusses white matter changes, with focus on oligodendrocyte lineage cells and their ability to produce and maintain myelin to support normal brain homoeostasis. Improved understanding of intrinsic cellular changes, general senescence mechanisms, intercellular interactions and alterations in extracellular environment which occur with aging and impact oligodendrocyte cells is paramount. This may lead to strategies to support oligodendrocytes in aging, for example by supporting myelin synthesis, protecting against oxidative stress and promoting the rejuvenation of the intrinsic regenerative potential of progenitor cells. Ultimately, this will enable the protection of white matter integrity thus protecting cognitive function into the later years of life.
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Affiliation(s)
- Eleanor Catherine Sams
- Blizard Institute, Barts and The London School of Medicine and Dentistry Centre for Neuroscience, Surgery and Trauma, Blizard Institute, 4 Newark Street, Whitechapel E1 2AT, London
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154
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Hanslik KL, Marino KM, Ulland TK. Modulation of Glial Function in Health, Aging, and Neurodegenerative Disease. Front Cell Neurosci 2021; 15:718324. [PMID: 34531726 PMCID: PMC8439422 DOI: 10.3389/fncel.2021.718324] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/27/2021] [Indexed: 01/15/2023] Open
Abstract
In the central nervous system (CNS), glial cells, such as microglia and astrocytes, are normally associated with support roles including contributions to energy metabolism, synaptic plasticity, and ion homeostasis. In addition to providing support for neurons, microglia and astrocytes function as the resident immune cells in the brain. The glial function is impacted by multiple aspects including aging and local CNS changes caused by neurodegeneration. During aging, microglia and astrocytes display alterations in their homeostatic functions. For example, aged microglia and astrocytes exhibit impairments in the lysosome and mitochondrial function as well as in their regulation of synaptic plasticity. Recent evidence suggests that glia can also alter the pathology associated with many neurodegenerative disorders including Alzheimer's disease (AD) and Parkinson's disease (PD). Shifts in the microbiome can impact glial function as well. Disruptions in the microbiome can lead to aberrant microglial and astrocytic reactivity, which can contribute to an exacerbation of disease and neuronal dysfunction. In this review, we will discuss the normal physiological functions of microglia and astrocytes, summarize novel findings highlighting the role of glia in aging and neurodegenerative diseases, and examine the contribution of microglia and astrocytes to disease progression.
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Affiliation(s)
- Kendra L. Hanslik
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Kaitlyn M. Marino
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Tyler K. Ulland
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
- Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI, United States
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155
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Wu Y, Shao W, Todd TW, Tong J, Yue M, Koga S, Castanedes-Casey M, Librero AL, Lee CW, Mackenzie IR, Dickson DW, Zhang YJ, Petrucelli L, Prudencio M. Microglial lysosome dysfunction contributes to white matter pathology and TDP-43 proteinopathy in GRN-associated FTD. Cell Rep 2021; 36:109581. [PMID: 34433069 PMCID: PMC8491969 DOI: 10.1016/j.celrep.2021.109581] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 06/07/2021] [Accepted: 07/29/2021] [Indexed: 11/04/2022] Open
Abstract
Loss-of-function mutations in the progranulin gene (GRN), which encodes progranulin (PGRN), are a major cause of frontotemporal dementia (FTD). GRN-associated FTD is characterized by TDP-43 inclusions and neuroinflammation, but how PGRN loss causes disease remains elusive. We show that Grn knockout (KO) mice have increased microgliosis in white matter and an accumulation of myelin debris in microglial lysosomes in the same regions. Accumulation of myelin debris is also observed in white matter of patients with GRN-associated FTD. In addition, our findings also suggest that PGRN insufficiency in microglia leads to impaired lysosomal-mediated clearance of myelin debris. Finally, Grn KO mice that are deficient in cathepsin D (Ctsd), a key lysosomal enzyme, have augmented myelin debris and increased neuronal TDP-43 pathology. Together, our data strongly imply that PGRN loss affects microglial activation and lysosomal function, resulting in the accumulation of myelin debris and contributing to TDP-43 pathology. Wu et al. show increased microgliosis in white matter of Grn knockout mice. Microglial lysosomes accumulate myelin debris in both Grn knockout mice and patients with GRN-associated FTD, and reducing cathespin D levels exacerbates both myelin debris accumulation and pTdp-43 aggregation. Thus, lysosomal dysfunction affects these pathologies in GRN-related FTD.
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Affiliation(s)
- Yanwei Wu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Wei Shao
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Tiffany W Todd
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Jimei Tong
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Mei Yue
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Shunsuke Koga
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | | | - Ariston L Librero
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Chris W Lee
- Atlantic Health System, Morristown, NJ 07960, USA; Biomedical Research Institute of New Jersey, Cedar Knolls, NJ 07927, USA
| | - Ian R Mackenzie
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55902, USA
| | - Yong-Jie Zhang
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55902, USA
| | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55902, USA.
| | - Mercedes Prudencio
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55902, USA.
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156
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Othman AH, Goh YM, Mohamed Mustapha N, Raghazli R, Kaka U, Imlan JC, Abubakar AA, Abdullah R. Physiological and electroencephalographic changes in goats subjected to transportation, lairage, and slaughter. Anim Sci J 2021; 92:e13610. [PMID: 34390058 DOI: 10.1111/asj.13610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 04/15/2021] [Accepted: 05/25/2021] [Indexed: 01/13/2023]
Abstract
This preliminary trial investigated the effect of transportation and lairage periods on physiological parameters of goats subjected to slaughter. Nine male Boer cross goats aged 8-12 months were transported for 6 h and kept at lairage for 3, 6, or 16 h (n = 3). Blood samples were collected at pre- (pre-T) and post-transportation (post-T), and post-slaughter (post-S) for determination of hematological parameters, serum enzyme, protein, and cortisol concentrations. Electroencephalogram readings were taken at pre-T, post-T, pre-slaughter (pre-S), and post-S to determine the median frequency (F50 ) and total power (Ptot) values. At post-T, there were manifestations of stress leukogram; increase in hematocrit, total protein, and muscle enzyme concentrations; and decrease in Ptot (p < 0.05). The high pre-T cortisol concentration suggests that the goats were already under stress before transportation. Stress leukogram became less evident after lairage, indicating that the goats had recovered from the stress of transportation. Although the Ptot increased at post-S especially following 3 h of lairage, F50 values at post-S did not differ from pre-L, suggesting that the pre-slaughter stress may have affected the pain threshold. It is suggested that after 6 h of transportation, goats should ideally be placed in lairage for a minimum period of 3 h before slaughter.
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Affiliation(s)
- Azalea-Hani Othman
- Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Malaysia
| | - Yong Meng Goh
- Department of Veterinary Preclinical Studies, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Malaysia.,Institute of Tropical Agriculture and Food Security, University Putra Malaysia, Serdang, Malaysia
| | - Noordin Mohamed Mustapha
- Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Malaysia
| | - Razlina Raghazli
- Department of Veterinary Preclinical Studies, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Malaysia.,Department of Veterinary Services, Ministry of Agriculture and Food Industry, Putrajaya, Malaysia
| | - Ubedullah Kaka
- Institute of Tropical Agriculture and Food Security, University Putra Malaysia, Serdang, Malaysia
| | - Jurhamid Columbres Imlan
- Institute of Tropical Agriculture and Food Security, University Putra Malaysia, Serdang, Malaysia.,Department of Animal Science, College of Agriculture, University of Southern Mindanao, Kabacan, The Philippines
| | - Ahmed Abubakar Abubakar
- Institute of Tropical Agriculture and Food Security, University Putra Malaysia, Serdang, Malaysia
| | - Rasedee Abdullah
- Department of Veterinary Laboratory Diagnosis, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Malaysia
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157
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Guerrero A, De Strooper B, Arancibia-Cárcamo IL. Cellular senescence at the crossroads of inflammation and Alzheimer's disease. Trends Neurosci 2021; 44:714-727. [PMID: 34366147 DOI: 10.1016/j.tins.2021.06.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 12/14/2022]
Abstract
Aging is a key risk factor for Alzheimer's disease (AD), but the reasons for this association are not well understood. Senescent cells accumulate in aged tissues and have been shown to play causal roles in age-related pathologies through their proinflammatory secretome. The question arises whether senescence-induced inflammation might contribute to AD and bridge the gap between aging and AD. Here, we highlight the role of cellular senescence as a driver of the aging phenotype, and discuss the current evidence that connects senescence with AD and neurodegeneration.
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Affiliation(s)
- Ana Guerrero
- UK Dementia Research Institute, Institute of Neurology, University College London, London WC1E 6BT, UK; The Francis Crick Institute, London NW1 1AT, UK
| | - Bart De Strooper
- UK Dementia Research Institute, Institute of Neurology, University College London, London WC1E 6BT, UK; The Francis Crick Institute, London NW1 1AT, UK; Department of Neurosciences, Leuven Brain Institute, Katholieke Universiteit (KU) Leuven, Leuven, Belgium; Vlaams Instituut voor Biotechnologie (VIB) Centre for Brain and Disease Research, Leuven, Belgium
| | - I Lorena Arancibia-Cárcamo
- UK Dementia Research Institute, Institute of Neurology, University College London, London WC1E 6BT, UK; The Francis Crick Institute, London NW1 1AT, UK.
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158
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Berdowski WM, Sanderson LE, van Ham TJ. The multicellular interplay of microglia in health and disease: lessons from leukodystrophy. Dis Model Mech 2021; 14:dmm048925. [PMID: 34282843 PMCID: PMC8319551 DOI: 10.1242/dmm.048925] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Microglia are highly dynamic cells crucial for developing and maintaining lifelong brain function and health through their many interactions with essentially all cellular components of the central nervous system. The frequent connection of microglia to leukodystrophies, genetic disorders of the white matter, has highlighted their involvement in the maintenance of white matter integrity. However, the mechanisms that underlie their putative roles in these processes remain largely uncharacterized. Microglia have also been gaining attention as possible therapeutic targets for many neurological conditions, increasing the demand to understand their broad spectrum of functions and the impact of their dysregulation. In this Review, we compare the pathological features of two groups of genetic leukodystrophies: those in which microglial dysfunction holds a central role, termed 'microgliopathies', and those in which lysosomal or peroxisomal defects are considered to be the primary driver. The latter are suspected to have notable microglia involvement, as some affected individuals benefit from microglia-replenishing therapy. Based on overlapping pathology, we discuss multiple ways through which aberrant microglia could lead to white matter defects and brain dysfunction. We propose that the study of leukodystrophies, and their extensively multicellular pathology, will benefit from complementing analyses of human patient material with the examination of cellular dynamics in vivo using animal models, such as zebrafish. Together, this will yield important insight into the cell biological mechanisms of microglial impact in the central nervous system, particularly in the development and maintenance of myelin, that will facilitate the development of new, and refinement of existing, therapeutic options for a range of brain diseases.
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Affiliation(s)
| | | | - Tjakko J. van Ham
- Department of Clinical Genetics, Erasmus MC University Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
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159
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Sinha A, Kushwaha R, Molesworth K, Mychko O, Makarava N, Baskakov IV. Phagocytic Activities of Reactive Microglia and Astrocytes Associated with Prion Diseases Are Dysregulated in Opposite Directions. Cells 2021; 10:1728. [PMID: 34359897 PMCID: PMC8304827 DOI: 10.3390/cells10071728] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 01/11/2023] Open
Abstract
Phagocytosis is one of the most important physiological functions of the glia directed at maintaining a healthy, homeostatic environment in the brain. Under a homeostatic environment, the phagocytic activities of astrocytes and microglia are tightly coordinated in time and space. In neurodegenerative diseases, both microglia and astrocytes contribute to neuroinflammation and disease pathogenesis, however, whether their phagocytic activities are up- or downregulated in reactive states is not known. To address this question, this current study isolated microglia and astrocytes from C57BL/6J mice infected with prions and tested their phagocytic activities in live-cell imaging assays that used synaptosomes and myelin debris as substrates. The phagocytic uptake by the reactive microglia was found to be significantly upregulated, whereas that of the reactive astrocytes was strongly downregulated. The up- and downregulation of phagocytosis by the two cell types were observed irrespective of whether disease-associated synaptosomes, normal synaptosomes, or myelin debris were used in the assays, indicating that dysregulations are dictated by cell reactive states, not substrates. Analysis of gene expression confirmed dysregulation of phagocytic functions in both cell types. Immunostaining of animal brains infected with prions revealed that at the terminal stage of disease, neuronal cell bodies were subject to engulfment by reactive microglia. This study suggests that imbalance in the phagocytic activities of the reactive microglia and astrocytes, which are dysregulated in opposite directions, is likely to lead to excessive microglia-mediated neuronal death on the one hand, and the inability of astrocytes to clear cell debris on the other hand, contributing to the neurotoxic effects of glia as a whole.
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Affiliation(s)
- Anshuman Sinha
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.S.); (R.K.); (K.M.); (O.M.); (N.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Rajesh Kushwaha
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.S.); (R.K.); (K.M.); (O.M.); (N.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kara Molesworth
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.S.); (R.K.); (K.M.); (O.M.); (N.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Olga Mychko
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.S.); (R.K.); (K.M.); (O.M.); (N.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Natallia Makarava
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.S.); (R.K.); (K.M.); (O.M.); (N.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ilia V. Baskakov
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.S.); (R.K.); (K.M.); (O.M.); (N.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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160
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Xu Y, Propson NE, Du S, Xiong W, Zheng H. Autophagy deficiency modulates microglial lipid homeostasis and aggravates tau pathology and spreading. Proc Natl Acad Sci U S A 2021; 118:e2023418118. [PMID: 34187889 PMCID: PMC8271658 DOI: 10.1073/pnas.2023418118] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The autophagy-lysosomal pathway plays a critical role in intracellular clearance and metabolic homeostasis. While neuronal autophagy is known to participate in the degradation of neurofibrillary tangles composed of hyperphosphorylated and misfolded tau protein in Alzheimer's disease and other tauopathies, how microglial-specific autophagy regulates microglial intrinsic properties and neuronal tau pathology is not well understood. We report here that Atg7, a key mediator of autophagosome biogenesis, plays an essential role in the regulation of microglial lipid metabolism and neuroinflammation. Microglia-specific deletion of Atg7 leads to the transition of microglia to a proinflammatory status in vivo and to inflammasome activation in vitro. Activation of ApoE and lipid efflux attenuates the lipid droplets accumulation and inhibits cytokine production in microglial cells with Atg7 deficiency. Functionally, we show that the absence of microglial Atg7 enhances intraneuronal tau pathology and its spreading. Our results reveal an essential role for microglial autophagy in regulating lipid homeostasis, neuroinflammation, and tau pathology.
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Affiliation(s)
- Yin Xu
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030;
| | - Nicholas E Propson
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030
| | - Shuqi Du
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Wen Xiong
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030
| | - Hui Zheng
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030;
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
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161
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Ralhan I, Chang CL, Lippincott-Schwartz J, Ioannou MS. Lipid droplets in the nervous system. J Cell Biol 2021; 220:e202102136. [PMID: 34152362 PMCID: PMC8222944 DOI: 10.1083/jcb.202102136] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 01/20/2023] Open
Abstract
Lipid droplets are dynamic intracellular lipid storage organelles that respond to the physiological state of cells. In addition to controlling cell metabolism, they play a protective role for many cellular stressors, including oxidative stress. Despite prior descriptions of lipid droplets appearing in the brain as early as a century ago, only recently has the role of lipid droplets in cells found in the brain begun to be understood. Lipid droplet functions have now been described for cells of the nervous system in the context of development, aging, and an increasing number of neuropathologies. Here, we review the basic mechanisms of lipid droplet formation, turnover, and function and discuss how these mechanisms enable lipid droplets to function in different cell types of the nervous system under healthy and pathological conditions.
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Affiliation(s)
- Isha Ralhan
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
| | - Chi-Lun Chang
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA
| | | | - Maria S. Ioannou
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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162
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Gustafsson T, Ulfhake B. Sarcopenia: What Is the Origin of This Aging-Induced Disorder? Front Genet 2021; 12:688526. [PMID: 34276788 PMCID: PMC8285098 DOI: 10.3389/fgene.2021.688526] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/10/2021] [Indexed: 01/03/2023] Open
Abstract
We here review the loss of muscle function and mass (sarcopenia) in the framework of human healthspan and lifespan, and mechanisms involved in aging. The rapidly changing composition of the human population will impact the incidence and the prevalence of aging-induced disorders such as sarcopenia and, henceforth, efforts to narrow the gap between healthspan and lifespan should have top priority. There are substantial knowledge gaps in our understanding of aging. Heritability is estimated to account for only 25% of lifespan length. However, as we push the expected lifespan at birth toward those that we consider long-lived, the genetics of aging may become increasingly important. Linkage studies of genetic polymorphisms to both the susceptibility and aggressiveness of sarcopenia are still missing. Such information is needed to shed light on the large variability in clinical outcomes between individuals and why some respond to interventions while others do not. We here make a case for the concept that sarcopenia has a neurogenic origin and that in manifest sarcopenia, nerve and myofibers enter into a vicious cycle that will escalate the disease progression. We point to gaps in knowledge, for example the crosstalk between the motor axon, terminal Schwann cell, and myofiber in the denervation processes that leads to a loss of motor units and muscle weakness. Further, we argue that the operational definition of sarcopenia should be complemented with dynamic metrics that, along with validated biomarkers, may facilitate early preclinical diagnosis of individuals vulnerable to develop advanced sarcopenia. We argue that preventive measures are likely to be more effective to counter act aging-induced disorders than efforts to treat manifest clinical conditions. To achieve compliance with a prescription of preventive measures that may be life-long, we need to identify reliable predictors to design rational and convincing interventions.
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Affiliation(s)
- Thomas Gustafsson
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Brun Ulfhake
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
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163
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De Schepper S, Crowley G, Hong S. Understanding microglial diversity and implications for neuronal function in health and disease. Dev Neurobiol 2021; 81:507-523. [PMID: 32757416 PMCID: PMC8438703 DOI: 10.1002/dneu.22777] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 06/21/2020] [Accepted: 07/31/2020] [Indexed: 12/22/2022]
Abstract
Genetic data implicate microglia as central players in brain health and disease, urging the need to better understand what microglia do in the brain. Microglia are critical partners in neuronal wiring and function during development and disease. Emerging literature suggests that microglia have diverse functional roles, raising the intriguing question of which functions of microglia become impaired in disease to undermine proper neuronal function. It is also becoming increasingly clear that microglia exist in heterogeneous cell states. Microglial cell states appear context-dependent, that is, age, sex, location, and health of their microenvironment; these are further influenced by external signaling factors including gut microbiota and lipid metabolites. These data altogether suggest that microglia exist in functional clusters that impact, and are impacted by, surrounding neuronal microenvironment. However, we still lack understanding of how we can translate microglia cell states into function. Here, we summarize the state-of-the-art on the diverse functions of microglia in relation to neuronal health. Then, we discuss heterogeneity during developing, healthy adult and diseased brains, and whether this may be predetermined by origin and/or regulated by local milieu. Finally, we propose that it is critical to gain high-resolution functional discernment into microglia-neuron interactions while preserving the spatial architecture of the tissue. Such insight will reveal specific targets for biomarker and therapeutic development toward microglia-neuron crosstalk in disease.
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Affiliation(s)
| | - Gerard Crowley
- UK Dementia Research InstituteUniversity College LondonLondonUK
| | - Soyon Hong
- UK Dementia Research InstituteUniversity College LondonLondonUK
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164
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Alexaki VI. The Impact of Obesity on Microglial Function: Immune, Metabolic and Endocrine Perspectives. Cells 2021; 10:cells10071584. [PMID: 34201844 PMCID: PMC8307603 DOI: 10.3390/cells10071584] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 06/18/2021] [Accepted: 06/22/2021] [Indexed: 02/06/2023] Open
Abstract
Increased life expectancy in combination with modern life style and high prevalence of obesity are important risk factors for development of neurodegenerative diseases. Neuroinflammation is a feature of neurodegenerative diseases, and microglia, the innate immune cells of the brain, are central players in it. The present review discusses the effects of obesity, chronic peripheral inflammation and obesity-associated metabolic and endocrine perturbations, including insulin resistance, dyslipidemia and increased glucocorticoid levels, on microglial function.
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Affiliation(s)
- Vasileia Ismini Alexaki
- Institute for Clinical Chemistry and Laboratory Medicine, University Clinic Carl Gustav Carus, TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
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165
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Burns TC, Quinones-Hinojosa A. Regenerative medicine for neurological diseases-will regenerative neurosurgery deliver? BMJ 2021; 373:n955. [PMID: 34162530 DOI: 10.1136/bmj.n955] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Regenerative medicine aspires to transform the future practice of medicine by providing curative, rather than palliative, treatments. Healing the central nervous system (CNS) remains among regenerative medicine's most highly prized but formidable challenges. "Regenerative neurosurgery" provides access to the CNS or its surrounding structures to preserve or restore neurological function. Pioneering efforts over the past three decades have introduced cells, neurotrophins, and genes with putative regenerative capacity into the CNS to combat neurodegenerative, ischemic, and traumatic diseases. In this review we critically evaluate the rationale, paradigms, and translational progress of regenerative neurosurgery, harnessing access to the CNS to protect, rejuvenate, or replace cell types otherwise irreversibly compromised by neurological disease. We discuss the evidence surrounding fetal, somatic, and pluripotent stem cell derived implants to replace endogenous neuronal and glial cell types and provide trophic support. Neurotrophin based strategies via infusions and gene therapy highlight the motivation to preserve neuronal circuits, the complex fidelity of which cannot be readily recreated. We specifically highlight ongoing translational efforts in Parkinson's disease, amyotrophic lateral sclerosis, stroke, and spinal cord injury, using these to illustrate the principles, challenges, and opportunities of regenerative neurosurgery. Risks of associated procedures and novel neurosurgical trials are discussed, together with the ethical challenges they pose. After decades of efforts to develop and refine necessary tools and methodologies, regenerative neurosurgery is well positioned to advance treatments for refractory neurological diseases. Strategic multidisciplinary efforts will be critical to harness complementary technologies and maximize mechanistic feedback, accelerating iterative progress toward cures for neurological diseases.
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Affiliation(s)
- Terry C Burns
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
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166
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Peruzzotti-Jametti L, Willis CM, Hamel R, Krzak G, Pluchino S. Metabolic Control of Smoldering Neuroinflammation. Front Immunol 2021; 12:705920. [PMID: 34249016 PMCID: PMC8262770 DOI: 10.3389/fimmu.2021.705920] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 05/31/2021] [Indexed: 12/11/2022] Open
Abstract
Compelling evidence exists that patients with chronic neurological conditions, which includes progressive multiple sclerosis, display pathological changes in neural metabolism and mitochondrial function. However, it is unknown if a similar degree of metabolic dysfunction occurs also in non-neural cells in the central nervous system. Specifically, it remains to be clarified (i) the full extent of metabolic changes in tissue-resident microglia and infiltrating macrophages after prolonged neuroinflammation (e.g., at the level of chronic active lesions), and (ii) whether these alterations underlie a unique pathogenic phenotype that is amenable for therapeutic targeting. Herein, we discuss how cell metabolism and mitochondrial function govern the function of chronic active microglia and macrophages brain infiltrates and identify new metabolic targets for therapeutic approaches aimed at reducing smoldering neuroinflammation.
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Affiliation(s)
- Luca Peruzzotti-Jametti
- Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
| | - Cory M Willis
- Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
| | - Regan Hamel
- Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
| | - Grzegorz Krzak
- Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
| | - Stefano Pluchino
- Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
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167
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Pannese E. Quantitative, structural and molecular changes in neuroglia of aging mammals: A review. Eur J Histochem 2021; 65. [PMID: 34346664 PMCID: PMC8239453 DOI: 10.4081/ejh.2021.3249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/27/2021] [Indexed: 01/06/2023] Open
Abstract
The neuroglia of the central and peripheral nervous systems undergo numerous changes during normal aging. Astrocytes become hypertrophic and accumulate intermediate filaments. Oligodendrocytes and Schwann cells undergo alterations that are often accompanied by degenerative changes to the myelin sheath. In microglia, proliferation in response to injury, motility of cell processes, ability to migrate to sites of neural injury, and phagocytic and autophagic capabilities are reduced. In sensory ganglia, the number and extent of gaps between perineuronal satellite cells – that leave the surfaces of sensory ganglion neurons directly exposed to basal lamina – increase significantly. The molecular profiles of neuroglia also change in old age, which, in view of the interactions between neurons and neuroglia, have negative consequences for important physiological processes in the nervous system. Since neuroglia actively participate in numerous nervous system processes, it is likely that not only neurons but also neuroglia will prove to be useful targets for interventions to prevent, reverse or slow the behavioral changes and cognitive decline that often accompany senescence.
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Affiliation(s)
- Ennio Pannese
- Emeritus, Full Professor of Normal Human Anatomy and Neurocytology at the University of Milan.
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168
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Disturbance of prefrontal cortical myelination in olfactory bulbectomized mice is associated with depressive-like behavior. Neurochem Int 2021; 148:105112. [PMID: 34171413 DOI: 10.1016/j.neuint.2021.105112] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/10/2021] [Accepted: 06/20/2021] [Indexed: 12/28/2022]
Abstract
Recent studies have reported that demyelination is associated with the development of depression. Olfactory bulbectomized (OBX) rodents are a useful experimental animal model for depressive disorder. However, little is known about the change in myelination in the brain of OBX mice. To address this question, we observed depressive-like behavior of OBX mice in the tail-suspension test, and determined the quantity of myelin proteins in the prefrontal cortex (PFC), striatum and hippocampus on day 14 or 21 after surgery. The number of nodes of Ranvier paired with the paranodal marker contactin-associated protein (Caspr), as well as the numbers of immature and mature oligodendrocytes in the PFC, were also measured on day 21 after surgery. We examined whether these behavioral and neurochemical changes observed in OBX mice were reversed by chronic administration of imipramine. OBX mice showed depressive-like behavior in the tail-suspension test together with a decrease in the levels of myelin proteins such as myelin basic protein, myelin-associated glycoprotein and cyclicnucleotide phosphodiesterase in the PFC on day 21 after surgery. The number of nodes of Ranvier and mature oligodendrocytes were also decreased in the PFC of OBX mice, while the number of immature oligodendrocytes was increased on day 21 after surgery. However, the number of immature oligodendrocytes in the PFC of OBX mice was decreased on day 35 after surgery. Administration of imipramine (20 mg/kg) for 2 weeks from day 21 after surgery improved OBX-induced depressive-like behavior and abnormal myelination in the PFC. The present findings suggest that the disturbance of myelin function in the PFC may contribute to the pathophysiology of depression, and further support the notion that it plays an important role in the psychological state.
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169
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Choi S, Guo L, Cordeiro MF. Retinal and Brain Microglia in Multiple Sclerosis and Neurodegeneration. Cells 2021; 10:cells10061507. [PMID: 34203793 PMCID: PMC8232741 DOI: 10.3390/cells10061507] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/28/2021] [Accepted: 06/11/2021] [Indexed: 12/24/2022] Open
Abstract
Microglia are the resident immune cells of the central nervous system (CNS), including the retina. Similar to brain microglia, retinal microglia are responsible for retinal surveillance, rapidly responding to changes in the environment by altering morphotype and function. Microglia become activated in inflammatory responses in neurodegenerative diseases, including multiple sclerosis (MS). When activated by stress stimuli, retinal microglia change their morphology and activity, with either beneficial or harmful consequences. In this review, we describe characteristics of CNS microglia, including those in the retina, with a focus on their morphology, activation states and function in health, ageing, MS and other neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, glaucoma and retinitis pigmentosa, to highlight their activity in disease. We also discuss contradictory findings in the literature and the potential ways of reducing inconsistencies in future by using standardised methodology, e.g., automated algorithms, to enable a more comprehensive understanding of this exciting area of research.
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Affiliation(s)
- Soyoung Choi
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (S.C.); (L.G.)
| | - Li Guo
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (S.C.); (L.G.)
| | - Maria Francesca Cordeiro
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (S.C.); (L.G.)
- ICORG, Imperial College London, London NW1 5QH, UK
- Correspondence:
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170
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Aires V, Coulon-Bainier C, Pavlovic A, Ebeling M, Schmucki R, Schweitzer C, Kueng E, Gutbier S, Harde E. CD22 Blockage Restores Age-Related Impairments of Microglia Surveillance Capacity. Front Immunol 2021; 12:684430. [PMID: 34140954 PMCID: PMC8204252 DOI: 10.3389/fimmu.2021.684430] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/17/2021] [Indexed: 11/13/2022] Open
Abstract
Microglia, the innate immune cells of the brain, are essential for maintaining homeostasis by their ramified, highly motile processes and for orchestrating the immune response to pathological stimuli. They are implicated in several neurodegenerative diseases like Alzheimer's and Parkinson's disease. One commonality of these diseases is their strong correlation with aging as the highest risk factor and studying age-related alterations in microglia physiology and associated signaling mechanism is indispensable for a better understanding of age-related pathomechanisms. CD22 has been identified as a modifier of microglia phagocytosis in a recent study, but not much is known about the function of CD22 in microglia. Here we show that CD22 surface levels are upregulated in aged versus adult microglia. Furthermore, in the amyloid mouse model PS2APP, Aβ-containing microglia also exhibit increased CD22 signal. To assess the impact of CD22 blockage on microglia morphology and dynamics, we have established a protocol to image microglia process motility in acutely prepared brain slices from CX3CR1-GFP reporter mice. We observed a significant reduction of microglial ramification and surveillance capacity in brain slices from aged versus adult mice. The age-related decrease in surveillance can be restored by antibody-mediated CD22 blockage in aged mice, whereas surveillance in adult mice is not affected by CD22 inhibition. Moreover to complement the results obtained in mice, we show that human iPSC-derived macrophages exhibit an increased phagocytic capacity upon CD22 blockage. Downstream analysis of antibody-mediated CD22 inhibition revealed an influence on BMP and TGFβ associated gene networks. Our results demonstrate CD22 as a broad age-associated modulator of microglia functionality with potential implications for neurodegenerative disorders.
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Affiliation(s)
- Vanessa Aires
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.,Department of Neurology, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Claire Coulon-Bainier
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Anto Pavlovic
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Martin Ebeling
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Roland Schmucki
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Christophe Schweitzer
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Erich Kueng
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Simon Gutbier
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Eva Harde
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
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171
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Lee E, Eo JC, Lee C, Yu JW. Distinct Features of Brain-Resident Macrophages: Microglia and Non-Parenchymal Brain Macrophages. Mol Cells 2021; 44:281-291. [PMID: 33972475 PMCID: PMC8175151 DOI: 10.14348/molcells.2021.0060] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/12/2021] [Accepted: 04/12/2021] [Indexed: 12/11/2022] Open
Abstract
Tissue-resident macrophages play an important role in maintaining tissue homeostasis and innate immune defense against invading microbial pathogens. Brain-resident macrophages can be classified into microglia in the brain parenchyma and non-parenchymal brain macrophages, also known as central nervous system-associated or border-associated macrophages, in the brain-circulation interface. Microglia and non-parenchymal brain macrophages, including meningeal, perivascular, and choroid plexus macrophages, are mostly produced during embryonic development, and maintained their population by self-renewal. Microglia have gained much attention for their dual roles in the maintenance of brain homeostasis and the induction of neuroinflammation. In particular, diverse phenotypes of microglia have been increasingly identified under pathological conditions. Single-cell phenotypic analysis revealed that microglia are highly heterogenous and plastic, thus it is difficult to define the status of microglia as M1/M2 or resting/activated state due to complex nature of microglia. Meanwhile, physiological function of non-parenchymal brain macrophages remain to be fully demonstrated. In this review, we have summarized the origin and signatures of brain-resident macrophages and discussed the unique features of microglia, particularly, their phenotypic polarization, diversity of subtypes, and inflammasome responses related to neurodegenerative diseases.
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Affiliation(s)
- Eunju Lee
- Department of Microbiology and Immunology, Institute for Immunology and Immunological Diseases, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Jun-Cheol Eo
- Department of Microbiology and Immunology, Institute for Immunology and Immunological Diseases, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Changjun Lee
- Department of Microbiology and Immunology, Institute for Immunology and Immunological Diseases, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Je-Wook Yu
- Department of Microbiology and Immunology, Institute for Immunology and Immunological Diseases, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Korea
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172
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The Microbiota-Gut-Brain Axis and Alzheimer Disease. From Dysbiosis to Neurodegeneration: Focus on the Central Nervous System Glial Cells. J Clin Med 2021; 10:jcm10112358. [PMID: 34072107 PMCID: PMC8199461 DOI: 10.3390/jcm10112358] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/21/2021] [Accepted: 05/24/2021] [Indexed: 02/06/2023] Open
Abstract
The microbiota-gut system can be thought of as a single unit that interacts with the brain via the "two-way" microbiota-gut-brain axis. Through this axis, a constant interplay mediated by the several products originating from the microbiota guarantees the physiological development and shaping of the gut and the brain. In the present review will be described the modalities through which the microbiota and gut control each other, and the main microbiota products conditioning both local and brain homeostasis. Much evidence has accumulated over the past decade in favor of a significant association between dysbiosis, neuroinflammation and neurodegeneration. Presently, the pathogenetic mechanisms triggered by molecules produced by the altered microbiota, also responsible for the onset and evolution of Alzheimer disease, will be described. Our attention will be focused on the role of astrocytes and microglia. Numerous studies have progressively demonstrated how these glial cells are important to ensure an adequate environment for neuronal activity in healthy conditions. Furthermore, it is becoming evident how both cell types can mediate the onset of neuroinflammation and lead to neurodegeneration when subjected to pathological stimuli. Based on this information, the role of the major microbiota products in shifting the activation profiles of astrocytes and microglia from a healthy to a diseased state will be discussed, focusing on Alzheimer disease pathogenesis.
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173
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Abstract
An aging-related reduction in the brain's functional reserve may explain why delirium is more frequent in the elderly than in younger people insofar as the reserve becomes inadequate to cover the metabolic requirements that are critically increased by stressors. The aim of this paper is to review the normal aging-related changes that theoretically compromise complex mental activities, neuronal and synaptic densities, and the neurocomputational flexibility of the functional reserve. A pivotal factor is diminished connectivity, which is substantially due to the loss of synapses and should specifically affect association systems and cholinergic fibres in delirious patients. However, micro-angiopathy with impaired blood flow autoregulation, increased blood/brain barrier permeability, changes in cerebrospinal fluid dynamics, weakened mitochondrial performance, and a pro-inflammatory involution of the immune system may also jointly affect neurons and their synaptic assets, and even cause the progression of delirium to dementia regardless of the presence of co-existing plaques, tangles, or other pathological markers. On the other hand, the developmental growth in functional reserve during childhood and adolescence makes the brain increasingly resistant to delirium, and residual reserve can allow the elderly to recover. These data support the view that functional reserve is the variable that confronts stressors and governs the risk and intensity of and recovery from delirium. Although people of any age are at risk of delirium, the elderly are at greater risk because aging and age-dependent structural changes inevitably affect the brain's functional reserve.
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174
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Balasubramanian P, Branen L, Sivasubramanian MK, Monteiro R, Subramanian M. Aging is associated with glial senescence in the brainstem - implications for age-related sympathetic overactivity. Aging (Albany NY) 2021; 13:13460-13473. [PMID: 34038388 PMCID: PMC8202881 DOI: 10.18632/aging.203111] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 04/28/2021] [Indexed: 12/11/2022]
Abstract
Accumulating evidence suggests that the sympathetic nervous system (SNS) overactivity plays a crucial role in age-related increase in the risk for cardiovascular diseases such as hypertension, myocardial infarction, stroke and heart diseases. Previous studies indicate that neuroinflammation in key brainstem regions that regulate sympathetic outflow plays a pathogenic role in aging-mediated sympathoexcitation. However, the molecular mechanisms underlying this phenomenon are not clear. While senescent cells and their secretory phenotype (SASP) have been implicated in the pathogenesis of several age-related diseases, their role in age-related neuroinflammation in the brainstem and SNS overactivity has not been investigated. To test this, we isolated brainstems from young (2-4 months) and aged (24 months) male C57BL/6J mice and assessed senescence using a combination of RNA-in situ hybridization, PCR analysis, multiplex assay and SA-β gal staining. Our results show significant increases in p16Ink4a expression, increased activity of SA-β gal and increases in SASP levels in the aged brainstem, suggesting age-induced senescence in the brainstem. Further, analysis of senescence markers in glial cells enriched fraction from fresh brainstem samples demonstrated that glial cells are more susceptible to senesce with age in the brainstem. In conclusion, our study suggests that aging induces glial senescence in the brainstem which likely causes inflammation and SNS overactivity.
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Affiliation(s)
- Priya Balasubramanian
- Oklahoma Center for Geroscience and Healthy Brain Aging, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Lyndee Branen
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Mahesh Kumar Sivasubramanian
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Raisa Monteiro
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Madhan Subramanian
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
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175
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Chen D, Nauen DW, Park HC, Li D, Yuan W, Li A, Guan H, Kut C, Chaichana KL, Bettegowda C, Quiñones-Hinojosa A, Li X. Label-free imaging of human brain tissue at subcellular resolution for potential rapid intra-operative assessment of glioma surgery. Am J Cancer Res 2021; 11:7222-7234. [PMID: 34158846 PMCID: PMC8210590 DOI: 10.7150/thno.59244] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/11/2021] [Indexed: 12/20/2022] Open
Abstract
Background: Frozen section and smear preparation are the current standard for intraoperative histopathology during cancer surgery. However, these methods are time-consuming and subject to limited sampling. Multiphoton microscopy (MPM) is a high-resolution non-destructive imaging technique capable of optical sectioning in real time with subcellular resolution. In this report, we systematically investigated the feasibility and translation potential of MPM for rapid histopathological assessment of label- and processing-free surgical specimens. Methods: We employed a customized MPM platform to capture architectural and cytological features of biological tissues based on two-photon excited NADH and FAD autofluorescence and second harmonic generation from collagen. Infiltrating glioma, an aggressive disease that requires subcellular resolution for definitive characterization during surgery, was chosen as an example for this validation study. MPM images were collected from resected brain specimens of 19 patients and correlated with histopathology. Deep learning was introduced to assist with image feature recognition. Results: MPM robustly captures diagnostic features of glioma including increased cellularity, cellular and nuclear pleomorphism, microvascular proliferation, necrosis, and collagen deposition. Preliminary application of deep learning to MPM images achieves high accuracy in distinguishing gray from white matter and cancer from non-cancer. We also demonstrate the ability to obtain such images from intact brain tissue with a multiphoton endomicroscope for intraoperative application. Conclusion: Multiphoton imaging correlates well with histopathology and is a promising tool for characterization of cancer and delineation of infiltration within seconds during brain surgery.
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176
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Costa J, Martins S, Ferreira PA, Cardoso AMS, Guedes JR, Peça J, Cardoso AL. The old guard: Age-related changes in microglia and their consequences. Mech Ageing Dev 2021; 197:111512. [PMID: 34022277 DOI: 10.1016/j.mad.2021.111512] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 12/17/2022]
Abstract
Among all major organs, the brain is one of the most susceptible to the inexorable effects of aging. Throughout the last decades, several studies in human cohorts and animal models have revealed a plethora of age-related changes in the brain, including reduced neurogenesis, oxidative damage, mitochondrial dysfunction and cell senescence. As the main immune effectors and first responders of the nervous tissue, microglia are at the center of these events. These cells experience irrevocable changes as a result from cumulative exposure to environmental triggers, such as stress, infection and metabolic dysregulation. The age-related immunosenescent phenotype acquired by microglia is characterized by profound modifications in their transcriptomic profile, secretome, morphology and phagocytic activity, which compromise both their housekeeping and defensive functions. As a result, aged microglia are no longer capable of establishing effective immune responses and sustaining normal synaptic activity, directly contributing to age-associated cognitive decline and neurodegeneration. This review discusses how lifestyle and environmental factors drive microglia dysfunction at the molecular and functional level, also highlighting possible interventions to reverse aging-associated damage to the nervous and immune systems.
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Affiliation(s)
- Jéssica Costa
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal; PhD Programme in Experimental Biology and Biomedicine (PDBEB), University of Coimbra, Coimbra, Portugal
| | - Solange Martins
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Pedro A Ferreira
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; PhD Program in Biosciences, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Ana M S Cardoso
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Joana R Guedes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - João Peça
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Ana L Cardoso
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal.
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177
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Fitzner D, Bader JM, Penkert H, Bergner CG, Su M, Weil MT, Surma MA, Mann M, Klose C, Simons M. Cell-Type- and Brain-Region-Resolved Mouse Brain Lipidome. Cell Rep 2021; 32:108132. [PMID: 32937123 DOI: 10.1016/j.celrep.2020.108132] [Citation(s) in RCA: 138] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 07/01/2020] [Accepted: 08/20/2020] [Indexed: 01/03/2023] Open
Abstract
Gene and protein expression data provide useful resources for understanding brain function, but little is known about the lipid composition of the brain. Here, we perform quantitative shotgun lipidomics, which enables a cell-type-resolved assessment of the mouse brain lipid composition. We quantify around 700 lipid species and evaluate lipid features including fatty acyl chain length, hydroxylation, and number of acyl chain double bonds, thereby identifying cell-type- and brain-region-specific lipid profiles in adult mice, as well as in aged mice, in apolipoprotein-E-deficient mice, in a model of Alzheimer's disease, and in mice fed different diets. We also integrate lipid with protein expression profiles to predict lipid pathways enriched in specific cell types, such as fatty acid β-oxidation in astrocytes and sphingolipid metabolism in microglia. This resource complements existing brain atlases of gene and protein expression and may be useful for understanding the role of lipids in brain function.
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Affiliation(s)
- Dirk Fitzner
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; Department of Neurology, University of Göttingen Medical Center, 37075 Göttingen, Germany.
| | - Jakob M Bader
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Horst Penkert
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany; Munich Cluster of Systems Neurology (SyNergy), 81377 Munich, Germany; Department of Neurology, School of Medicine, Technical University of Munich (TUM), 81675 Munich, Germany
| | - Caroline G Bergner
- Department of Neurology, University of Göttingen Medical Center, 37075 Göttingen, Germany; Department of Neuropathology, University of Göttingen Medical Center, 37075 Göttingen, Germany
| | - Minhui Su
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany
| | - Marie-Theres Weil
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | | | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Clinical Proteomics Group, Proteomics Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | | | - Mikael Simons
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany; Munich Cluster of Systems Neurology (SyNergy), 81377 Munich, Germany.
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178
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Radiation Triggers a Dynamic Sequence of Transient Microglial Alterations in Juvenile Brain. Cell Rep 2021; 31:107699. [PMID: 32492415 DOI: 10.1016/j.celrep.2020.107699] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 10/08/2019] [Accepted: 05/06/2020] [Indexed: 11/21/2022] Open
Abstract
Cranial irradiation (IR), an effective tool to treat malignant brain tumors, triggers a chronic pro-inflammatory microglial response, at least in the adult brain. Using single-cell and bulk RNA sequencing, combined with histology, we show that the microglial response in the juvenile mouse hippocampus is rapid but returns toward normal within 1 week. The response is characterized by a series of temporally distinct homeostasis-, sensome-, and inflammation-related molecular signatures. We find that a single microglial cell simultaneously upregulates transcripts associated with pro- and anti-inflammatory microglial phenotypes. Finally, we show that juvenile and adult irradiated microglia are already transcriptionally distinct in the early phase after IR. Our results indicate that microglia are involved in the initial stages but may not be responsible for driving long-term inflammation in the juvenile brain.
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179
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Greenwood EK, Brown DR. Senescent Microglia: The Key to the Ageing Brain? Int J Mol Sci 2021; 22:4402. [PMID: 33922383 PMCID: PMC8122783 DOI: 10.3390/ijms22094402] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/13/2022] Open
Abstract
Ageing represents the single biggest risk factor for development of neurodegenerative disease. Despite being such long-lived cells, microglia have been relatively understudied for their role in the ageing process. Reliably identifying aged microglia has proven challenging, not least due to the diversity of cell populations, and the limitations of available models, further complicated by differences between human and rodent cells. Consequently, the literature contains multiple descriptions and categorisations of microglia with neurotoxic phenotypes, including senescence, without any unifying markers. The role of microglia in brain homeostasis, particularly iron storage and metabolism, may provide a key to reliable identification.
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Affiliation(s)
| | - David R. Brown
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK;
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180
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Microglial heterogeneity in aging and Alzheimer's disease: Is sex relevant? J Pharmacol Sci 2021; 146:169-181. [PMID: 34030799 DOI: 10.1016/j.jphs.2021.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 02/24/2021] [Accepted: 03/22/2021] [Indexed: 02/08/2023] Open
Abstract
Neurodegenerative diseases and their associated cognitive decline are known to be more prevalent during aging. Recent evidence has uncovered the role of microglia, the immunocompetent cells of the brain, in dysfunctions linked to neurodegenerative diseases such as is Alzheimer's disease (AD). Similar to other pathologies, AD is shown to be sex-biased, with females being more at risk compared to males. While the mechanisms driving this prevalence are still unclear, emerging data suggest the sex differences present in microglia throughout life might lead to different responses of these cells in both health and disease. Furthermore, microglial cells have recently been recognized as a deeply heterogeneous population, with multiple subsets and/or phenotypes stemming from diverse parameters such as age, sex or state of health. Therefore, this review discusses microglial heterogeneity during aging in both basal conditions and AD with a focus on existing sex differences in this process.
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181
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Oligodendrocyte Development and Regenerative Therapeutics in Multiple Sclerosis. Life (Basel) 2021; 11:life11040327. [PMID: 33918664 PMCID: PMC8069894 DOI: 10.3390/life11040327] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 12/23/2022] Open
Abstract
Myelination by oligodendrocytes (OLs) is an important biological process essential for central nervous system (CNS) development and functions. Oligodendroglial lineage cells undergo several morphological and molecular changes at different stages of their lineage progression into myelinating OLs. The transition steps of the oligodendrocyte progenitor cells (OPCs) to myelinating oligodendrocytes are defined by a specific pattern of regulated gene expression, which is under the control of coordinated signaling pathways. Any abnormal development, loss or failure of oligodendrocytes to myelinate axons can lead to several neurodegenerative diseases like multiple sclerosis (MS). MS is characterized by inflammation and demyelination, and current treatments target only the immune component of the disease, but have little impact on remyelination. Recently, several pharmacological compounds enhancing remyelination have been identified and some of them are in clinical trials. Here, we will review the current knowledge on oligodendrocyte differentiation, myelination and remyelination. We will focus on MS as a pathological condition, the most common chronic inflammatory demyelinating disease of the CNS in young adults.
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182
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Chen Y, Hong T, Chen F, Sun Y, Wang Y, Cui L. Interplay Between Microglia and Alzheimer's Disease-Focus on the Most Relevant Risks: APOE Genotype, Sex and Age. Front Aging Neurosci 2021; 13:631827. [PMID: 33897406 PMCID: PMC8060487 DOI: 10.3389/fnagi.2021.631827] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 03/18/2021] [Indexed: 12/20/2022] Open
Abstract
As the main immune cells of the central nervous system (CNS), microglia regulates normal development, homeostasis and general brain physiology. These functions put microglia at the forefront of CNS repair and recovery. Uncontrolled activation of microglia is related to the course of neurodegenerative diseases such as Alzheimer’s disease. It is clear that the classic pathologies of amyloid β (Aβ) and Tau are usually accompanied by the activation of microglia, and the activation of microglia also serves as an early event in the pathogenesis of AD. Therefore, during the occurrence and development of AD, the key susceptibility factors for AD—apolipoprotein E (APOE) genotype, sex and age—may further interact with microglia to exacerbate neurodegeneration. In this review, we discuss the role of microglia in the progression of AD related to the three risk factors for AD: APOE genotype, sex and aging. APOE-expressing microglia accumulates around Aβ plaques, and the presence of APOE4 may disrupt the phagocytosis of Aβ aggregates and aggravate neurodegeneration in Tau disease models. In addition, females have a high incidence of AD, and normal female microglia and estrogen have protective effects under normal conditions. However, under the influence of AD, female microglia seem to lose their protective effect and instead accelerate the course of AD. Aging, another major risk factor, may increase the sensitivity of microglia, leading to the exacerbation of microglial dysfunction in elderly AD. Obviously, in the role of microglia in AD, the three main risk factors of APOE, sex, and aging are not independent and have synergistic effects that contribute to the risk of AD. Moreover, new microglia can replace dysfunctional microglia after microglial depletion, which is a new promising strategy for AD treatment.
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Affiliation(s)
- Yanting Chen
- Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Tingting Hong
- Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Feng Chen
- Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Yuanhong Sun
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Yan Wang
- Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Lili Cui
- Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
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183
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Groh J, Knöpper K, Arampatzi P, Yuan X, Lößlein L, Saliba AE, Kastenmüller W, Martini R. Accumulation of cytotoxic T cells in the aged CNS leads to axon degeneration and contributes to cognitive and motor decline. NATURE AGING 2021; 1:357-367. [PMID: 37117598 DOI: 10.1038/s43587-021-00049-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 02/23/2021] [Indexed: 04/30/2023]
Abstract
Aging is a major risk factor for the development of nervous system functional decline, even in the absence of diseases or trauma. The axon-myelin units and synaptic terminals are some of the neural structures most vulnerable to aging-related deterioration1-6, but the underlying mechanisms are poorly understood. In the peripheral nervous system, macrophages-important representatives of the innate immune system-are prominent drivers of structural and functional decline of myelinated fibers and motor endplates during aging7. Similarly, in the aging central nervous system (CNS), microglial cells promote damage of myelinated axons and synapses8-20. Here we examine the role of cytotoxic CD8+ T lymphocytes, a type of adaptive immune cells previously identified as amplifiers of axonal perturbation in various models of genetically mediated CNS diseases21 but understudied in the aging CNS22-25. We show that accumulation of CD8+ T cells drives axon degeneration in the normal aging mouse CNS and contributes to age-related cognitive and motor decline. We characterize CD8+ T-cell population heterogeneity in the adult and aged mouse brain by single-cell transcriptomics and identify aging-related changes. Mechanistically, we provide evidence that CD8+ T cells drive axon degeneration in a T-cell receptor- and granzyme B-dependent manner. Cytotoxic neural damage is further aggravated by systemic inflammation in aged but not adult mice. We also find increased densities of T cells in white matter autopsy material from older humans. Our results suggest that targeting CD8+ CNS-associated T cells in older adults might mitigate aging-related decline of brain structure and function.
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Affiliation(s)
- Janos Groh
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany.
| | - Konrad Knöpper
- Institute for Systems Immunology, University of Würzburg, Würzburg, Germany
| | | | - Xidi Yuan
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Lena Lößlein
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Antoine-Emmanuel Saliba
- Helmholtz Institute for RNA-based Infection Research, Helmholtz-Center for Infection Research, Würzburg, Germany
| | | | - Rudolf Martini
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
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184
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Campagno KE, Mitchell CH. The P2X 7 Receptor in Microglial Cells Modulates the Endolysosomal Axis, Autophagy, and Phagocytosis. Front Cell Neurosci 2021; 15:645244. [PMID: 33790743 PMCID: PMC8005553 DOI: 10.3389/fncel.2021.645244] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/22/2021] [Indexed: 01/18/2023] Open
Abstract
Microglial cells regulate neural homeostasis by coordinating both immune responses and clearance of debris, and the P2X7 receptor for extracellular ATP plays a central role in both functions. The P2X7 receptor is primarily known in microglial cells for its immune signaling and NLRP3 inflammasome activation. However, the receptor also affects the clearance of extracellular and intracellular debris through modifications of lysosomal function, phagocytosis, and autophagy. In the absence of an agonist, the P2X7 receptor acts as a scavenger receptor to phagocytose material. Transient receptor stimulation induces autophagy and increases LC3-II levels, likely through calcium-dependent phosphorylation of AMPK, and activates microglia to an M1 or mixed M1/M2 state. We show an increased expression of Nos2 and Tnfa and a decreased expression of Chil3 (YM1) from primary cultures of brain microglia exposed to high levels of ATP. Sustained stimulation can reduce lysosomal function in microglia by increasing lysosomal pH and slowing autophagosome-lysosome fusion. P2X7 receptor stimulation can also cause lysosomal leakage, and the subsequent rise in cytoplasmic cathepsin B activates the NLRP3 inflammasome leading to caspase-1 cleavage and IL-1β maturation and release. Support for P2X7 receptor activation of the inflammasome following lysosomal leakage comes from data on primary microglia showing IL-1β release following receptor stimulation is inhibited by cathepsin B blocker CA-074. This pathway bridges endolysosomal and inflammatory roles and may provide a key mechanism for the increased inflammation found in age-dependent neurodegenerations characterized by excessive lysosomal accumulations. Regardless of whether the inflammasome is activated via this lysosomal leakage or the better-known K+-efflux pathway, the inflammatory impact of P2X7 receptor stimulation is balanced between the autophagic reduction of inflammasome components and their increase following P2X7-mediated priming. In summary, the P2X7 receptor modulates clearance of extracellular debris by microglial cells and mediates lysosomal damage that can activate the NLRP3 inflammasome. A better understanding of how the P2X7 receptor alters phagocytosis, lysosomal health, inflammation, and autophagy can lead to therapies that balance the inflammatory and clearance roles of microglial cells.
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Affiliation(s)
- Keith E Campagno
- Department of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA, United States
| | - Claire H Mitchell
- Department of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA, United States.,Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, United States.,Department of Physiology, University of Pennsylvania, Philadelphia, PA, United States
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185
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Abstract
Myelination of axons provides the structural basis for rapid saltatory impulse propagation along vertebrate fiber tracts, a well-established neurophysiological concept. However, myelinating oligodendrocytes and Schwann cells serve additional functions in neuronal energy metabolism that are remarkably similar to those of axon-ensheathing glial cells in unmyelinated invertebrates. Here we discuss myelin evolution and physiological glial functions, beginning with the role of ensheathing glia in preventing ephaptic coupling, axoglial metabolic support, and eliminating oxidative radicals. In both vertebrates and invertebrates, axoglial interactions are bidirectional, serving to regulate cell fate, nerve conduction, and behavioral performance. One key step in the evolution of compact myelin in the vertebrate lineage was the emergence of the open reading frame for myelin basic protein within another gene. Several other proteins were neofunctionalized as myelin constituents and help maintain a healthy nervous system. Myelination in vertebrates became a major prerequisite of inhabiting new ecological niches.
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Affiliation(s)
- Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany; ,
| | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany; ,
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186
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Lysosomal Functions in Glia Associated with Neurodegeneration. Biomolecules 2021; 11:biom11030400. [PMID: 33803137 PMCID: PMC7999372 DOI: 10.3390/biom11030400] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/03/2021] [Accepted: 03/08/2021] [Indexed: 12/12/2022] Open
Abstract
Lysosomes are cellular organelles that contain various acidic digestive enzymes. Despite their small size, they have multiple functions. Lysosomes remove or recycle unnecessary cell parts. They repair damaged cellular membranes by exocytosis. Lysosomes also sense cellular energy status and transmit signals to the nucleus. Glial cells are non-neuronal cells in the nervous system and have an active role in homeostatic support for neurons. In response to dynamic cues, glia use lysosomal pathways for the secretion and uptake of regulatory molecules, which affect the physiology of neighboring neurons. Therefore, functional aberration of glial lysosomes can trigger neuronal degeneration. Here, we review lysosomal functions in oligodendrocytes, astrocytes, and microglia, with emphasis on neurodegeneration.
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187
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Go V, Sarikaya D, Zhou Y, Bowley BGE, Pessina MA, Rosene DL, Zhang ZG, Chopp M, Finklestein SP, Medalla M, Buller B, Moore TL. Extracellular vesicles derived from bone marrow mesenchymal stem cells enhance myelin maintenance after cortical injury in aged rhesus monkeys. Exp Neurol 2021; 337:113540. [PMID: 33264634 PMCID: PMC7946396 DOI: 10.1016/j.expneurol.2020.113540] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 11/05/2020] [Accepted: 11/24/2020] [Indexed: 12/20/2022]
Abstract
Cortical injury, such as stroke, causes neurotoxic cascades that lead to rapid death and/or damage to neurons and glia. Axonal and myelin damage in particular, are critical factors that lead to neuronal dysfunction and impair recovery of function after injury. These factors can be exacerbated in the aged brain where white matter damage is prevalent. Therapies that can ameliorate myelin damage and promote repair by targeting oligodendroglia, the cells that produce and maintain myelin, may facilitate recovery after injury, especially in the aged brain where these processes are already compromised. We previously reported that a novel therapeutic, Mesenchymal Stem Cell derived extracellular vesicles (MSC-EVs), administered intravenously at both 24 h and 14 days after cortical injury, reduced microgliosis (Go et al. 2019), reduced neuronal pathology (Medalla et al. 2020), and improved motor recovery (Moore et al. 2019) in aged female rhesus monkeys. Here, we evaluated the effect of MSC-EV treatment on changes in oligodendrocyte maturation and associated myelin markers in the sublesional white matter using immunohistochemistry, confocal microscopy, stereology, qRT-PCR, and ELISA. Compared to vehicle control monkeys, EV-treated monkeys showed a reduction in the density of damaged oligodendrocytes. Further, EV-treatment was associated with enhanced myelin maintenance, evidenced by upregulation of myelin-related genes and increases in actively myelinating oligodendrocytes in sublesional white matter. These changes in myelination correlate with the rate of motor recovery, suggesting that improved myelin maintenance facilitates this recovery. Overall, our results suggest that EVs act on oligodendrocytes to support myelination and improves functional recovery after injury in the aged brain. SIGNIFICANCE: We previously reported that EVs facilitate recovery of function after cortical injury in the aged monkey brain, while also reducing neuronal pathology (Medalla et al. 2020) and microgliosis (Go et al. 2019). However, the effect of injury and EVs on oligodendrocytes and myelination has not been characterized in the primate brain (Dewar et al. 1999; Sozmen et al. 2012; Zhang et al. 2013). In the present study, we assessed changes in myelination after cortical injury in aged monkeys. Our results show, for the first time, that MSC-EVs support recovery of function after cortical injury by enhancing myelin maintenance in the aged primate brain.
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Affiliation(s)
- Veronica Go
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, United States.
| | - Deniz Sarikaya
- Research Center for Translational Medicine, Koç University School of Medicine, Turkey
| | - Yuxin Zhou
- Department of Anatomy & Neurobiology, Boston University School of Medicine, United States
| | - Bethany G E Bowley
- Department of Anatomy & Neurobiology, Boston University School of Medicine, United States
| | - Monica A Pessina
- Department of Anatomy & Neurobiology, Boston University School of Medicine, United States
| | - Douglas L Rosene
- Department of Anatomy & Neurobiology, Boston University School of Medicine, United States; Yerkes National Primate Research Center, Emory University, United States; Center for Systems Neuroscience, Boston University, United States
| | - Zheng Gang Zhang
- Department of Neurology, Henry Ford Health Systems, United States
| | - Michael Chopp
- Department of Neurology, Henry Ford Health Systems, United States; Department of Physics, Oakland University, United States
| | - Seth P Finklestein
- Department of Neurology, Massachusetts General Hospital, United States; Stemetix, Inc., United States
| | - Maria Medalla
- Department of Anatomy & Neurobiology, Boston University School of Medicine, United States; Center for Systems Neuroscience, Boston University, United States
| | - Benjamin Buller
- Department of Neurology, Henry Ford Health Systems, United States
| | - Tara L Moore
- Department of Anatomy & Neurobiology, Boston University School of Medicine, United States; Center for Systems Neuroscience, Boston University, United States
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188
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Schirmer L, Schafer DP, Bartels T, Rowitch DH, Calabresi PA. Diversity and Function of Glial Cell Types in Multiple Sclerosis. Trends Immunol 2021; 42:228-247. [PMID: 33593693 PMCID: PMC7914214 DOI: 10.1016/j.it.2021.01.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/04/2021] [Accepted: 01/07/2021] [Indexed: 12/25/2022]
Abstract
Glial subtype diversity is an emerging topic in neurobiology and immune-mediated neurological diseases such as multiple sclerosis (MS). We discuss recent conceptual and technological advances that allow a better understanding of the transcriptomic and functional heterogeneity of oligodendrocytes (OLs), astrocytes, and microglial cells under inflammatory-demyelinating conditions. Recent single cell transcriptomic studies suggest the occurrence of novel homeostatic and reactive glial subtypes and provide insight into the molecular events during disease progression. Multiplexed RNA in situ hybridization has enabled 'mapping back' dysregulated gene expression to glial subtypes within the MS lesion microenvironment. These findings suggest novel homeostatic and reactive glial-cell-type functions both in immune-related processes and neuroprotection relevant to understanding the pathology of MS.
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Affiliation(s)
- Lucas Schirmer
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Center for Translational Neuroscience and Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany.
| | - Dorothy P Schafer
- Department of Neurobiology and the Brudnik Neuropsychiatric Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - Theresa Bartels
- Department of Paediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - David H Rowitch
- Department of Paediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK; Departments of Pediatrics and Neurosurgery, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, USA
| | - Peter A Calabresi
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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189
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Loss of NPC1 enhances phagocytic uptake and impairs lipid trafficking in microglia. Nat Commun 2021; 12:1158. [PMID: 33627648 PMCID: PMC7904859 DOI: 10.1038/s41467-021-21428-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 01/27/2021] [Indexed: 02/08/2023] Open
Abstract
Niemann-Pick type C disease is a rare neurodegenerative disorder mainly caused by mutations in NPC1, resulting in abnormal late endosomal/lysosomal lipid storage. Although microgliosis is a prominent pathological feature, direct consequences of NPC1 loss on microglial function remain not fully characterized. We discovered pathological proteomic signatures and phenotypes in NPC1-deficient murine models and demonstrate a cell autonomous function of NPC1 in microglia. Loss of NPC1 triggers enhanced phagocytic uptake and impaired myelin turnover in microglia that precede neuronal death. Npc1−/− microglia feature a striking accumulation of multivesicular bodies and impaired trafficking of lipids to lysosomes while lysosomal degradation function remains preserved. Molecular and functional defects were also detected in blood-derived macrophages of NPC patients that provide a potential tool for monitoring disease. Our study underscores an essential cell autonomous role for NPC1 in immune cells and implies microglial therapeutic potential. Niemann-Pick type C disease is a rare childhood neurodegenerative disorder predominantly caused by mutations in NPC1, resulting in abnormal late endosomal and lysosomal defects. Here the authors show that NPC1 disruption largely impairs microglial function.
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190
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Gonçalves de Andrade E, Šimončičová E, Carrier M, Vecchiarelli HA, Robert MÈ, Tremblay MÈ. Microglia Fighting for Neurological and Mental Health: On the Central Nervous System Frontline of COVID-19 Pandemic. Front Cell Neurosci 2021; 15:647378. [PMID: 33737867 PMCID: PMC7961561 DOI: 10.3389/fncel.2021.647378] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 01/15/2021] [Indexed: 12/15/2022] Open
Abstract
Coronavirus disease 2019 (COVID-19) is marked by cardio-respiratory alterations, with increasing reports also indicating neurological and psychiatric symptoms in infected individuals. During COVID-19 pathology, the central nervous system (CNS) is possibly affected by direct severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invasion, exaggerated systemic inflammatory responses, or hypoxia. Psychosocial stress imposed by the pandemic further affects the CNS of COVID-19 patients, but also the non-infected population, potentially contributing to the emergence or exacerbation of various neurological or mental health disorders. Microglia are central players of the CNS homeostasis maintenance and inflammatory response that exert their crucial functions in coordination with other CNS cells. During homeostatic challenges to the brain parenchyma, microglia modify their density, morphology, and molecular signature, resulting in the adjustment of their functions. In this review, we discuss how microglia may be involved in the neuroprotective and neurotoxic responses against CNS insults deriving from COVID-19. We examine how these responses may explain, at least partially, the neurological and psychiatric manifestations reported in COVID-19 patients and the general population. Furthermore, we consider how microglia might contribute to increased CNS vulnerability in certain groups, such as aged individuals and people with pre-existing conditions.
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Affiliation(s)
| | - Eva Šimončičová
- Division of Medical Science, University of Victoria, Victoria, BC, Canada
| | - Micaël Carrier
- Division of Medical Science, University of Victoria, Victoria, BC, Canada.,Axe Neurosciences, Centre de Recherche du CHU de Québec, Université de Laval, Québec City, QC, Canada
| | | | - Marie-Ève Robert
- Axe Neurosciences, Centre de Recherche du CHU de Québec, Université de Laval, Québec City, QC, Canada
| | - Marie-Ève Tremblay
- Division of Medical Science, University of Victoria, Victoria, BC, Canada.,Axe Neurosciences, Centre de Recherche du CHU de Québec, Université de Laval, Québec City, QC, Canada.,Neurology and Neurosurgery Department, McGill University, Montréal, QC, Canada.,Department of Molecular Medicine, Université de Laval, Québec City, QC, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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191
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Safaiyan S, Besson-Girard S, Kaya T, Cantuti-Castelvetri L, Liu L, Ji H, Schifferer M, Gouna G, Usifo F, Kannaiyan N, Fitzner D, Xiang X, Rossner MJ, Brendel M, Gokce O, Simons M. White matter aging drives microglial diversity. Neuron 2021; 109:1100-1117.e10. [PMID: 33606969 DOI: 10.1016/j.neuron.2021.01.027] [Citation(s) in RCA: 198] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/08/2020] [Accepted: 01/26/2021] [Indexed: 01/08/2023]
Abstract
Aging results in gray and white matter degeneration, but the specific microglial responses are unknown. Using single-cell RNA sequencing from white and gray matter separately, we identified white matter-associated microglia (WAMs), which share parts of the disease-associated microglia (DAM) gene signature and are characterized by activation of genes implicated in phagocytic activity and lipid metabolism. WAMs depend on triggering receptor expressed on myeloid cells 2 (TREM2) signaling and are aging dependent. In the aged brain, WAMs form independent of apolipoprotein E (APOE), in contrast to mouse models of Alzheimer's disease, in which microglia with the WAM gene signature are generated prematurely and in an APOE-dependent pathway similar to DAMs. Within the white matter, microglia frequently cluster in nodules, where they are engaged in clearing degenerated myelin. Thus, WAMs may represent a potentially protective response required to clear degenerated myelin accumulating during white matter aging and disease.
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Affiliation(s)
- Shima Safaiyan
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany
| | - Simon Besson-Girard
- Institute for Stroke and Dementia Research, University Hospital of Munich, LMU Munich, 81377 Munich, Germany
| | - Tuğberk Kaya
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany; Institute for Stroke and Dementia Research, University Hospital of Munich, LMU Munich, 81377 Munich, Germany
| | - Ludovico Cantuti-Castelvetri
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany
| | - Lu Liu
- Institute for Stroke and Dementia Research, University Hospital of Munich, LMU Munich, 81377 Munich, Germany
| | - Hao Ji
- Institute for Stroke and Dementia Research, University Hospital of Munich, LMU Munich, 81377 Munich, Germany
| | - Martina Schifferer
- German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany
| | - Garyfallia Gouna
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany
| | - Fumere Usifo
- Institute for Stroke and Dementia Research, University Hospital of Munich, LMU Munich, 81377 Munich, Germany
| | - Nirmal Kannaiyan
- Department of Psychiatry, Ludwig-Maximilians-Universität, 80336 Munich, Germany
| | - Dirk Fitzner
- Department of Neurology, University of Göttingen, 37075 Göttingen, Germany
| | - Xianyuan Xiang
- Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität Munich, 81377 Munich, Germany
| | - Moritz J Rossner
- Department of Psychiatry, Ludwig-Maximilians-Universität, 80336 Munich, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital of Munich, LMU Munich, 81377 Munich, Germany; Munich Cluster of Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Ozgun Gokce
- Institute for Stroke and Dementia Research, University Hospital of Munich, LMU Munich, 81377 Munich, Germany; Munich Cluster of Systems Neurology (SyNergy), 81377 Munich, Germany.
| | - Mikael Simons
- Institute of Neuronal Cell Biology, Technical University Munich, 80802 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), 81377 Munich, Germany; Munich Cluster of Systems Neurology (SyNergy), 81377 Munich, Germany.
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192
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Rajani RM, Dupré N, Domenga-Denier V, Van Niel G, Heiligenstein X, Joutel A. Characterisation of early ultrastructural changes in the cerebral white matter of CADASIL small vessel disease using high-pressure freezing/freeze-substitution. Neuropathol Appl Neurobiol 2021; 47:694-704. [PMID: 33483954 DOI: 10.1111/nan.12697] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/08/2021] [Accepted: 01/15/2021] [Indexed: 11/29/2022]
Abstract
AIMS The objective of this study was to elucidate the early white matter changes in CADASIL small vessel disease. METHODS We used high-pressure freezing and freeze substitution (HPF/FS) in combination with high-resolution electron microscopy (EM), immunohistochemistry and confocal microscopy of brain specimens from control and CADASIL (TgNotch3R169C ) mice aged 4-15 months to study white matter lesions in the corpus callosum. RESULTS We first optimised the HPF/FS protocol in which samples were chemically prefixed, frozen in a sample carrier filled with 20% polyvinylpyrrolidone and freeze-substituted in a cocktail of tannic acid, osmium tetroxide and uranyl acetate dissolved in acetone. EM analysis showed that CADASIL mice exhibit significant splitting of myelin layers and enlargement of the inner tongue of small calibre axons from the age of 6 months, then vesiculation of the inner tongue and myelin sheath thinning at 15 months of age. Immunohistochemistry revealed an increased number of oligodendrocyte precursor cells, although only in older mice, but no reduction in the number of mature oligodendrocytes at any age. The number of Iba1 positive microglial cells was increased in older but not in younger CADASIL mice, but the number of activated microglial cells (Iba1 and CD68 positive) was unchanged at any age. CONCLUSION We conclude that early WM lesions in CADASIL affect first and foremost the myelin sheath and the inner tongue, suggestive of a primary myelin injury. We propose that those defects are consistent with a hypoxic/ischaemic mechanism.
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Affiliation(s)
- Rikesh M Rajani
- Institute of Psychiatry and Neurosciences of Paris, Inserm U1266, Université de Paris, Paris, France
| | - Nicolas Dupré
- Institute of Psychiatry and Neurosciences of Paris, Inserm U1266, Université de Paris, Paris, France
| | - Valérie Domenga-Denier
- Institute of Psychiatry and Neurosciences of Paris, Inserm U1266, Université de Paris, Paris, France
| | - Guillaume Van Niel
- Institute of Psychiatry and Neurosciences of Paris, Inserm U1266, Université de Paris, Paris, France.,GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France
| | | | - Anne Joutel
- Institute of Psychiatry and Neurosciences of Paris, Inserm U1266, Université de Paris, Paris, France.,GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France.,Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT, USA
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193
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Wan B, Li C, Wang M, Kong F, Ding Q, Zhang C, Liu H, Qian D, Deng W, Chen J, Tang P, Wang Q, Zhao S, Zhou Z, Xu T, Huang Y, Gu J, Fan J, Yin G. GIT1 protects traumatically injured spinal cord by prompting microvascular endothelial cells to clear myelin debris. Aging (Albany NY) 2021; 13:7067-7083. [PMID: 33621952 PMCID: PMC7993661 DOI: 10.18632/aging.202560] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/27/2020] [Indexed: 12/12/2022]
Abstract
The clearance of myelin debris is a critical step in the functional recovery following spinal cord injury (SCI). As phagocytes do, microvascular endothelial cells (MECs) participate in myelin debris clearance at the injury site within one week. Our group has verified that G protein-coupled receptor kinase 2 interacting protein-1 (GIT1) is essential in autophagy and angiogenesis, both of which are tightly related to the uptake and degradation of myelin debris by MECs. Here, we analyzed the performance and mechanism of GIT1 in myelin debris clearance after SCI. The SCI contusion model was established and in vitro MECs were treated with myelin debris. Better recovery from traumatic SCI was observed in the GIT1 WT mice than in the GIT1 KO mice. More importantly, we found that GIT1 prompted MECs to clear myelin debris and further enhanced MECs angiogenesis in vivo and in vitro. Mechanistically, GIT1-mediated autophagy contributed to the clearance of myelin debris by MECs. In this study, we demonstrated that GIT1 may prompt MECs to clear myelin debris via autophagy and further stimulate MECs angiogenesis via upregulating VEGF. Our results indicate that GITI may serve as a promising target for accelerating myelin debris clearance and improving SCI recovery.
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Affiliation(s)
- Bowen Wan
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Cong Li
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Ming Wang
- Department of Plastic and Burn Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Fanqi Kong
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai 200003, China
| | - Qirui Ding
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Chenliang Zhang
- Department of Orthopedics, The Affiliated Shuyang Hospital of Xuzhou Medical University, Suqian 223600, China
| | - Hao Liu
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Dingfei Qian
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Wenlin Deng
- Department of Orthopedics, The Affiliated Suqian First People's Hospital of Nanjing Medical University, Suqian 223800, China
| | - Jian Chen
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Pengyu Tang
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Qian Wang
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Shujie Zhao
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Zheng Zhou
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Tao Xu
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Yifan Huang
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Jun Gu
- Department of Orthopedics, Xishan People's Hospital, Wuxi 214000, China
| | - Jin Fan
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Guoyong Yin
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
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194
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Batterman KV, Cabrera PE, Moore TL, Rosene DL. T Cells Actively Infiltrate the White Matter of the Aging Monkey Brain in Relation to Increased Microglial Reactivity and Cognitive Decline. Front Immunol 2021; 12:607691. [PMID: 33664743 PMCID: PMC7920950 DOI: 10.3389/fimmu.2021.607691] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/25/2021] [Indexed: 02/06/2023] Open
Abstract
Normal aging is characterized by declines in processing speed, learning, memory, and executive function even in the absence of neurodegenerative diseases such as Alzheimer's Disease (AD). In normal aging monkeys and humans, neuronal loss does not account for cognitive impairment. Instead, loss of white matter volume and an accumulation of myelin sheath pathology begins in middle age and is associated with cognitive decline. It is unknown what causes this myelin pathology, but it likely involves increased neuroinflammation in white matter and failures in oligodendrocyte function (maturation and repair). In frontal white matter tracts vulnerable to myelin damage, microglia become chronically reactive and secrete harmful pro-inflammatory cytokines. Despite being in a phagocytic state, these microglia are ineffective at phagocytosing accruing myelin debris, which directly inhibits myelin sheath repair. Here, we asked whether reported age-related increases in pro-inflammatory markers were accompanied by an adaptive immune response involving T cells. We quantified T cells with immunohistochemistry in the brains of 34 cognitively characterized monkeys and found an age-related increase in perivascular T cells that surround CNS vasculature. We found a surprising age-related increase in T cells that infiltrate the white matter parenchyma. In the cingulum bundle the percentage of these parenchymal T cells increased with age relative to those in the perivascular space. In contrast, infiltrating T cells were rarely found in surrounding gray matter regions. We assessed whether T cell infiltration correlated with fibrinogen extravasation from the vasculature as a measure of BBB leakiness and found no correlation, suggesting that T cell infiltration is not a result of passive extravasation. Importantly, the density of T cells in the cingulum bundle correlated with microglial reactivity and with cognitive impairment. This is the first demonstration that T cell infiltration of white matter is associated with cognitive decline in the normal aging monkey.
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Affiliation(s)
- Katelyn V Batterman
- Laboratory for Cognitive Neurobiology, Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA, United States
| | - Payton E Cabrera
- Laboratory for Cognitive Neurobiology, Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA, United States
| | - Tara L Moore
- Laboratory for Cognitive Neurobiology, Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA, United States.,Laboratory of Interventions for Cortical Injury and Cognitive Decline, Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA, United States.,Center for Systems Neuroscience, Boston University, Boston, MA, United States
| | - Douglas L Rosene
- Laboratory for Cognitive Neurobiology, Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA, United States.,Center for Systems Neuroscience, Boston University, Boston, MA, United States
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195
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Lee JW, Lee IH, Iimura T, Kong SW. Two macrophages, osteoclasts and microglia: from development to pleiotropy. Bone Res 2021; 9:11. [PMID: 33568650 PMCID: PMC7875961 DOI: 10.1038/s41413-020-00134-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 11/23/2020] [Accepted: 11/26/2020] [Indexed: 12/11/2022] Open
Abstract
Tissue-resident macrophages are highly specialized to their tissue-specific microenvironments, activated by various inflammatory signals and modulated by genetic and environmental factors. Osteoclasts and microglia are distinct tissue-resident cells of the macrophage lineage in bone and brain that are responsible for pathological changes in osteoporosis and Alzheimer’s disease (AD), respectively. Osteoporosis is more frequently observed in individuals with AD compared to the prevalence in general population. Diagnosis of AD is often delayed until underlying pathophysiological changes progress and cause irreversible damages in structure and function of brain. As such earlier diagnosis and intervention of individuals at higher risk would be indispensable to modify clinical courses. Pleiotropy is the phenomenon that a genetic variant affects multiple traits and the genetic correlation between two traits could suggest a shared molecular mechanism. In this review, we discuss that the Pyk2-mediated actin polymerization pathway in osteoclasts and microglia in bone and brain, respectively, is the horizontal pleiotropic mediator of shared risk factors for osteoporosis and AD.
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Affiliation(s)
- Ji-Won Lee
- Department of Nephrology, Transplant Research Program, Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Pharmacology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, 060-8586, Japan
| | - In-Hee Lee
- Computational Health Informatics Program, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Tadahiro Iimura
- Department of Pharmacology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, 060-8586, Japan
| | - Sek Won Kong
- Computational Health Informatics Program, Boston Children's Hospital, Boston, MA, 02115, USA. .,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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196
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Prinz M, Masuda T, Wheeler MA, Quintana FJ. Microglia and Central Nervous System-Associated Macrophages-From Origin to Disease Modulation. Annu Rev Immunol 2021; 39:251-277. [PMID: 33556248 DOI: 10.1146/annurev-immunol-093019-110159] [Citation(s) in RCA: 232] [Impact Index Per Article: 77.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The immune system of the central nervous system (CNS) consists primarily of innate immune cells. These are highly specialized macrophages found either in the parenchyma, called microglia, or at the CNS interfaces, such as leptomeningeal, perivascular, and choroid plexus macrophages. While they were primarily thought of as phagocytes, their function extends well beyond simple removal of cell debris during development and diseases. Brain-resident innate immune cells were found to be plastic, long-lived, and host to an outstanding number of risk genes for multiple pathologies. As a result, they are now considered the most suitable targets for modulating CNS diseases. Additionally, recent single-cell technologies enhanced our molecular understanding of their origins, fates, interactomes, and functional cell statesduring health and perturbation. Here, we review the current state of our understanding and challenges of the myeloid cell biology in the CNS and treatment options for related diseases.
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Affiliation(s)
- Marco Prinz
- Institute of Neuropathology, Faculty of Medicine, University of Freiburg, D-79106 Freiburg, Germany; .,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, D-79106 Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies and Centre for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, D-79104 Freiburg, Germany
| | - Takahiro Masuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, 812-8582 Fukuoka, Japan;
| | - Michael A Wheeler
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA; , .,Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Francisco J Quintana
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA; , .,Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
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197
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Srimat Kandadai K, Kotur MB, Dokalis N, Amrein I, Keller CW, Münz C, Wolfer D, Prinz M, Lünemann JD. ATG5 in microglia does not contribute vitally to autoimmune neuroinflammation in mice. Autophagy 2021; 17:3566-3576. [PMID: 33522362 DOI: 10.1080/15548627.2021.1883880] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Microglia, resident myeloid immune cells of the central nervous system (CNS), actively shape the circuitry of the brain, maintain CNS homeostasis during the steady state and orchestrate immune responses upon CNS injury. Both canonical and non-canonical functions of the macroautophagy/autophagy-related protein ATG5 regulate myeloid cell survival and immune responses. Here, we report that loss of ATG5 in postnatal microglia does not perturb CNS tissue integrity, microglial cell survival, or immune activation. Learning task performances were unchanged in mutant mice. Furthermore, lack of ATG5 expression in microglia had no impact on the development of experimental autoimmune encephalomyelitis. These data indicate that, basal autophagy, identified to be essential for the survival and function of neuronal cells, is not required to maintain CNS homeostasis if absent in adult microglia and ATG5 expression is dispensable for the development of autoimmune neuroinflammation.Abbreviations Ag, antigen; APC, antigen presenting cell; ATG/Atg, autophagy-related; CD, cluster of differentiation; CNS, central nervous system; DC, dendritic cell; EAE, experimental autoimmune encephalomyelitis; fl, floxed; LAP, LC3-associated phagocytosis; LC3, microtubule-associated protein 1 light chain 3; MFI, median fluorescence intensity; MHCII, major histocompatibility complex class II; MOG, myelin oligodendrocyte glycoprotein; MS, multiple sclerosis.
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Affiliation(s)
- Keertana Srimat Kandadai
- Department of Neurology with Institute of Translational Neurology, University of Münster, Münster, Germany
| | - Monika B Kotur
- Laboratory of Neuroinflammation, Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Nikolaos Dokalis
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Irmgard Amrein
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Christian W Keller
- Department of Neurology with Institute of Translational Neurology, University of Münster, Münster, Germany.,Laboratory of Neuroinflammation, Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Christian Münz
- Laboratory of Viral Immunobiology, Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - David Wolfer
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Marco Prinz
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany.,Institute of Neuropathology, University of Freiburg; Signalling Research Centres BIOSS and CIBSS, University of Freiburg; Center for Basics in NeuroModulation (Neuromodulbasics), University of Freiburg, Germany
| | - Jan D Lünemann
- Department of Neurology with Institute of Translational Neurology, University of Münster, Münster, Germany.,Laboratory of Neuroinflammation, Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
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198
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Allende ML, Zhu H, Kono M, Hoachlander-Hobby LE, Huso VL, Proia RL. Genetic defects in the sphingolipid degradation pathway and their effects on microglia in neurodegenerative disease. Cell Signal 2021; 78:109879. [PMID: 33296739 PMCID: PMC7775721 DOI: 10.1016/j.cellsig.2020.109879] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022]
Abstract
Sphingolipids, which function as plasma membrane lipids and signaling molecules, are highly enriched in neuronal and myelin membranes in the nervous system. They are degraded in lysosomes by a defined sequence of enzymatic steps. In the related group of disorders, the sphingolipidoses, mutations in the genes that encode the individual degradative enzymes cause lysosomal accumulation of sphingolipids and often result in severe neurodegenerative disease. Here we review the information indicating that microglia, which actively clear sphingolipid-rich membranes in the brain during development and homeostasis, are directly affected by these mutations and promote neurodegeneration in the sphingolipidoses. We also identify parallels between the sphingolipidoses and more common forms of neurodegeneration, which both exhibit evidence of defective sphingolipid clearance in the nervous system.
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Affiliation(s)
- Maria L Allende
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hongling Zhu
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mari Kono
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lila E Hoachlander-Hobby
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vienna L Huso
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard L Proia
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA.
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199
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Abstract
PURPOSE OF REVIEW In multiple sclerosis, currently approved disease-modifying treatments are effective in modulating peripheral immunity, and coherently, in reducing clinical/radiological relapses, but still, they perform poorly in preventing disease progression and overall disability accrual. This review provides an up-to-date overview of the neuropathology of progressive multiple sclerosis, including a summary of the main mechanisms of disease progression. RECENT FINDINGS Clinical progression in multiple sclerosis is likely related to the accumulation of neuro-axonal loss in a lifelong inflammatory CNS environment (both adaptive and innate) and relative un-balance between damage, repair and brain functional reserve. A critical driver appears to be the T-cell and B-cell-mediated compartmentalized inflammation within the leptomeninges and within the parenchyma. Recent perspective highlighted also the role of the glial response to such lifelong inflammatory injury as the critical player for both pathological and clinical outcomes. SUMMARY The neuropathological and biological understanding of disease progression in multiple sclerosis have progressed in the last few years. As a consequence, new therapeutic approaches are emerging outside the modulation of T-cell activity and/or the depletion of B cells.
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The aging mouse brain: cognition, connectivity and calcium. Cell Calcium 2021; 94:102358. [PMID: 33517250 DOI: 10.1016/j.ceca.2021.102358] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/16/2021] [Accepted: 01/18/2021] [Indexed: 02/08/2023]
Abstract
Aging is a complex process that differentially impacts multiple cognitive, sensory, neuronal and molecular processes. Technological innovations now allow for parallel investigation of neuronal circuit function, structure and molecular composition in the brain of awake behaving adult mice. Thus, mice have become a critical tool to better understand how aging impacts the brain. However, a more granular systems-based approach, which considers the impact of age on key features relating to neural processing, is required. Here, we review evidence probing the impact of age on the mouse brain. We focus on a range of processes relating to neuronal function, including cognitive abilities, sensory systems, synaptic plasticity and calcium regulation. Across many systems, we find evidence for prominent age-related dysregulation even before 12 months of age, suggesting that emerging age-related alterations can manifest by late adulthood. However, we also find reports suggesting that some processes are remarkably resilient to aging. The evidence suggests that aging does not drive a parallel, linear dysregulation of all systems, but instead impacts some processes earlier, and more severely, than others. We propose that capturing the more fine-scale emerging features of age-related vulnerability and resilience may provide better opportunities for the rejuvenation of the aged brain.
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