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von Bernhardi R, Eugenín J. Aging Microglia and Their Impact in the Nervous System. ADVANCES IN NEUROBIOLOGY 2024; 37:379-395. [PMID: 39207703 DOI: 10.1007/978-3-031-55529-9_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Aging is the greatest risk factor for neurodegenerative diseases. Microglia are the resident immune cells in the central nervous system (CNS), playing key roles in its normal functioning, and as mediators for age-dependent changes of the CNS, condition at which they generate a hostile environment for neurons. Transforming Growth Factor β1 (TGFβ1) is a regulatory cytokine involved in immuneregulation and neuroprotection, affecting glial cell inflammatory activation, neuronal survival, and function. TGFβ1 signaling undergoes age-dependent changes affecting the regulation of microglial cells and can contribute to the pathophysiology of neurodegenerative diseases. This chapter focuses on assessing the role of age-related changes on the regulation of microglial cells and their impact on neuroinflammation and neuronal function, for understanding age-dependent changes of the nervous system.
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Affiliation(s)
- Rommy von Bernhardi
- Faculty of Odontology and Rehabilitation Sciences, Universidad San Sebastian, Santiago, Chile.
| | - Jaime Eugenín
- Faculty of Chemistry and Biology, Universidad de Santiago de Chile, Santiago, Chile
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2
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Ma Y, Wang W, Liu S, Qiao X, Xing Y, Zhou Q, Zhang Z. Epigenetic Regulation of Neuroinflammation in Alzheimer's Disease. Cells 2023; 13:79. [PMID: 38201283 PMCID: PMC10778497 DOI: 10.3390/cells13010079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/25/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disease and clinically manifests with cognitive decline and behavioral disabilities. Over the past years, mounting studies have demonstrated that the inflammatory response plays a key role in the onset and development of AD, and neuroinflammation has been proposed as the third major pathological driving factor of AD, ranking after the two well-known core pathologies, amyloid β (Aβ) deposits and neurofibrillary tangles (NFTs). Epigenetic mechanisms, referring to heritable changes in gene expression independent of DNA sequence alterations, are crucial regulators of neuroinflammation which have emerged as potential therapeutic targets for AD. Upon regulation of transcriptional repression or activation, epigenetic modification profiles are closely involved in inflammatory gene expression and signaling pathways of neuronal differentiation and cognitive function in central nervous system disorders. In this review, we summarize the current knowledge about epigenetic control mechanisms with a focus on DNA and histone modifications involved in the regulation of inflammatory genes and signaling pathways in AD, and the inhibitors under clinical assessment are also discussed.
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Affiliation(s)
- Yajing Ma
- College of Biology and Food, Shangqiu Normal University, Shangqiu 476000, China;
| | - Wang Wang
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China; (W.W.); (Y.X.)
| | - Sufang Liu
- Department of Biomedical Sciences, College of Dentistry, Texas A&M University, Dallas, TX 75246, USA;
| | - Xiaomeng Qiao
- Department of Pathology and Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China;
| | - Ying Xing
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China; (W.W.); (Y.X.)
| | - Qingfeng Zhou
- College of Biology and Food, Shangqiu Normal University, Shangqiu 476000, China;
| | - Zhijian Zhang
- College of Biology and Food, Shangqiu Normal University, Shangqiu 476000, China;
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Eugenín J, Eugenín-von Bernhardi L, von Bernhardi R. Age-dependent changes on fractalkine forms and their contribution to neurodegenerative diseases. Front Mol Neurosci 2023; 16:1249320. [PMID: 37818457 PMCID: PMC10561274 DOI: 10.3389/fnmol.2023.1249320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/06/2023] [Indexed: 10/12/2023] Open
Abstract
The chemokine fractalkine (FKN, CX3CL1), a member of the CX3C subfamily, contributes to neuron-glia interaction and the regulation of microglial cell activation. Fractalkine is expressed by neurons as a membrane-bound protein (mCX3CL1) that can be cleaved by extracellular proteases generating several sCX3CL1 forms. sCX3CL1, containing the chemokine domain, and mCX3CL1 have high affinity by their unique receptor (CX3CR1) which, physiologically, is only found in microglia, a resident immune cell of the CNS. The activation of CX3CR1contributes to survival and maturation of the neural network during development, glutamatergic synaptic transmission, synaptic plasticity, cognition, neuropathic pain, and inflammatory regulation in the adult brain. Indeed, the various CX3CL1 forms appear in some cases to serve an anti-inflammatory role of microglia, whereas in others, they have a pro-inflammatory role, aggravating neurological disorders. In the last decade, evidence points to the fact that sCX3CL1 and mCX3CL1 exhibit selective and differential effects on their targets. Thus, the balance in their level and activity will impact on neuron-microglia interaction. This review is focused on the description of factors determining the emergence of distinct fractalkine forms, their age-dependent changes, and how they contribute to neuroinflammation and neurodegenerative diseases. Changes in the balance among various fractalkine forms may be one of the mechanisms on which converge aging, chronic CNS inflammation, and neurodegeneration.
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Affiliation(s)
- Jaime Eugenín
- Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, Santiago, Chile
| | | | - Rommy von Bernhardi
- Facultad de Ciencias para el Cuidado de la Salud, Universidad San Sebastián, Santiago, Chile
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Xie Y, Jia Y, Li Z, Hu F. Scavenger receptor A in immunity and autoimmune diseases: Compelling evidence for targeted therapy. Expert Opin Ther Targets 2022; 26:461-477. [PMID: 35510370 DOI: 10.1080/14728222.2022.2072729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Scavenger receptor A (SR-A) is reported to be involved in innate and adaptive immunity and in recent years, the soluble form of SR-A has also been identified. Intriguingly, SR-A displays double-edged sword features in different diseases. Moreover, targeted therapy on SR-A, including genetic modulation, small molecule inhibitor, inhibitory peptides, fucoidan, and blocking antibodies, provides potential strategies for treatment. Currently, therapeutics targeting SR-A are in preclinical studies and clinical trials, revealing great perspectives in future immunotherapy. AREAS COVERED Through searching PubMed (January 1979-March 2022) and clinicaltrials.gov, we review most of the research and clinical trials involving SR-A. This review briefly summarizes recent study advances on SR-A, with particular concern on its role in immunity and autoimmune diseases. EXPERT OPINION Given the emerging evidence of SR-A in immunity, its targeted therapy has been studied in various diseases, especially autoimmune diseases. However, many challenges still remain to be overcome, such as the double-sworded effects and the specific isoform targeting. For further clinical success of SR-A targeted therapy, the crystal structure illustration and the dual function discrimination of SR-A should be further investigated. Nevertheless, although challenging, targeting SR-A would be a potential effective strategy in the treatment of autoimmune diseases and other immune-related diseases.
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Affiliation(s)
- Yang Xie
- Department of Rheumatology and Immunology, Peking University People's Hospital & Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, Peking, China
| | - Yuan Jia
- Department of Rheumatology and Immunology, Peking University People's Hospital & Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, Peking, China
| | - Zhanguo Li
- Department of Rheumatology and Immunology, Peking University People's Hospital & Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, Peking, China.,State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, Peking, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, Peking, China
| | - Fanlei Hu
- Department of Rheumatology and Immunology, Peking University People's Hospital & Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, Peking, China.,State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, Peking, China.,Department of Integration of Chinese and Western Medicine, School of Basic Medical Sciences, Peking University, Beijing, Peking, China
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Inflammation: A New Look at an Old Problem. Int J Mol Sci 2022; 23:ijms23094596. [PMID: 35562986 PMCID: PMC9100490 DOI: 10.3390/ijms23094596] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/17/2022] [Accepted: 04/19/2022] [Indexed: 02/07/2023] Open
Abstract
Pro-inflammatory stress is inherent in any cells that are subject to damage or threat of damage. It is defined by a number of universal components, including oxidative stress, cellular response to DNA damage, unfolded protein response to mitochondrial and endoplasmic reticulum stress, changes in autophagy, inflammasome formation, non-coding RNA response, formation of an inducible network of signaling pathways, and epigenetic changes. The presence of an inducible receptor and secretory phenotype in many cells is the cause of tissue pro-inflammatory stress. The key phenomenon determining the occurrence of a classical inflammatory focus is the microvascular inflammatory response (exudation, leukocyte migration to the alteration zone). This same reaction at the systemic level leads to the development of life-critical systemic inflammation. From this standpoint, we can characterize the common mechanisms of pathologies that differ in their clinical appearance. The division of inflammation into alternative variants has deep evolutionary roots. Evolutionary aspects of inflammation are also described in the review. The aim of the review is to provide theoretical arguments for the need for an up-to-date theory of the relationship between key human pathological processes based on the integrative role of the molecular mechanisms of cellular and tissue pro-inflammatory stress.
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Yoshimura A, Ohyagi M, Ito M. T cells in the brain inflammation. Adv Immunol 2022; 157:29-58. [PMID: 37061287 DOI: 10.1016/bs.ai.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The immune system is deeply involved in autoimmune diseases of the central nervous system (CNS), such as multiple sclerosis, N-methyl-d-aspartate (NMDA) receptor encephalitis, and narcolepsy. Additionally, the immune system is involved in various brain diseases including cerebral infarction and neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). In particular, reports related to T cells are increasing. T cells may also play important roles in brain deterioration and dementia that occur with aging. Our understanding of the role of immune cells in the context of the brain has been greatly improved by the use of acute ischemic brain injury models. Additionally, similar neural damage and repair events are shown to occur in more chronic brain neurodegenerative brain diseases. In this review, we focus on the role of T cells, including CD4+ T cells, CD8+ T cells and regulatory T cells (Tregs) in cerebral infarction and neurodegenerative diseases.
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Zhang G, Wang Z, Hu H, Zhao M, Sun L. Microglia in Alzheimer's Disease: A Target for Therapeutic Intervention. Front Cell Neurosci 2021; 15:749587. [PMID: 34899188 PMCID: PMC8651709 DOI: 10.3389/fncel.2021.749587] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 10/28/2021] [Indexed: 12/31/2022] Open
Abstract
Alzheimer’s disease (AD) is one of the most common types of age-related dementia worldwide. In addition to extracellular amyloid plaques and intracellular neurofibrillary tangles, dysregulated microglia also play deleterious roles in the AD pathogenesis. Numerous studies have demonstrated that unbridled microglial activity induces a chronic neuroinflammatory environment, promotes β-amyloid accumulation and tau pathology, and impairs microglia-associated mitophagy. Thus, targeting microglia may pave the way for new therapeutic interventions. This review provides a thorough overview of the pathophysiological role of the microglia in AD and illustrates the potential avenues for microglia-targeted therapies, including microglial modification, immunoreceptors, and anti-inflammatory drugs.
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Affiliation(s)
- Guimei Zhang
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Jilin University, Changchun, China
| | - Zicheng Wang
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Jilin University, Changchun, China
| | - Huiling Hu
- Department of Intensive Care Unit, The Affiliated Hospital of Qingdao University, Shandong, China
| | - Meng Zhao
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Jilin University, Changchun, China
| | - Li Sun
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Jilin University, Changchun, China
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8
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Catania M, Di Fede G. One or more β-amyloid(s)? New insights into the prion-like nature of Alzheimer's disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 175:213-237. [PMID: 32958234 DOI: 10.1016/bs.pmbts.2020.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Misfolding and aggregation of proteins play a central role in the pathogenesis of several neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's and Lewy Body diseases, Frontotemporal Lobar Degeneration and prion diseases. Increasing evidence supports the view that Aβ and tau, which are the two main molecular players in AD, share with the prion protein several "prion-like" features that can be relevant for disease pathogenesis. These features essentially include structural/conformational/biochemical variations, resistance to degradation by endogenous proteases, seeding ability, attitude to form neurotoxic assemblies, spreading and propagation of toxic aggregates, transmissibility of tau- and Aβ-related pathology to animal models. Following this view, part of the recent scientific literature has generated a new reading frame for AD pathophysiology, based on the application of the prion paradigm to the amyloid cascade hypothesis in an attempt to definitely explain the key events causing the disease and inducing its occurrence under different clinical phenotypes.
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Affiliation(s)
- Marcella Catania
- Neurology 5 / Neuropathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Giuseppe Di Fede
- Neurology 5 / Neuropathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
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Scavenger Receptor-A deficiency impairs immune response of microglia and astrocytes potentiating Alzheimer's disease pathophysiology. Brain Behav Immun 2018; 69:336-350. [PMID: 29246456 DOI: 10.1016/j.bbi.2017.12.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 12/25/2022] Open
Abstract
Late onset Alzheimer disease's (LOAD) main risk factor is aging. Although it is not well known which age-related factors are involved in its development, evidence points out to the involvement of an impaired amyloid-β (Aβ) clearance in the aged brain among possible causes. Glial cells are the main scavengers of the brain, where Scavenger Receptor class A (SR-A) emerges as a relevant player in AD because of its participation in Aβ uptake and in the modulation of glial cell inflammatory response. Here, we show that SR-A expression is reduced in the hippocampus of aged animals and APP/PS1 mice. Given that Aβ deposition increases in the aging brain, we generated a triple transgenic mouse, which accumulates Aβ and is knockout for SR-A (APP/PS1/SR-A-/-) to evaluate Aβ accumulation and the inflammatory outcome of SR-A depletion in the aged brain. The lifespan of APP/PS1/SR-A-/- mice was greatly reduced, accompanied by a 3-fold increase in plasmatic pro-inflammatory cytokines, and reduced performance in a working memory behavioral assessment. Microglia and astrocytes lacking SR-A displayed impaired oxidative response and nitric oxide production, produced up to 7-fold more pro-inflammatory cytokines and showed a 12-fold reduction in anti-inflammatory cytokines release, with conspicuous changes in lipopolysaccharide-induced glial activation. Isolated microglia from young and adult mice lacking SR-A showed a 50% reduction in phagocytic activity. Our results indicate that reduced expression of SR-A can deregulate glial inflammatory response and potentiate Aβ accumulation, two mechanisms that could contribute to AD progression.
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Murta V, Schilrreff P, Rosciszewski G, Morilla MJ, Ramos AJ. G5G2.5 core-shell tecto-dendrimer specifically targets reactive glia in brain ischemia. J Neurochem 2018; 144:748-760. [DOI: 10.1111/jnc.14286] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 11/18/2017] [Accepted: 12/11/2017] [Indexed: 01/02/2023]
Affiliation(s)
- Veronica Murta
- Departamento de Histología, Embriología, Biología Celular y Genética; Facultad de Medicina; Universidad de Buenos Aires; Buenos Aires Argentina
- Laboratorio de Neuropatología Molecular; Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis” IBCN UBA-CONICET; Buenos Aires Argentina
| | - Priscila Schilrreff
- Programa de Nanomedicinas; Departamento de Ciencia y Tecnología; Universidad Nacional de Quilmes; Bernal Argentina
| | - Gerardo Rosciszewski
- Departamento de Histología, Embriología, Biología Celular y Genética; Facultad de Medicina; Universidad de Buenos Aires; Buenos Aires Argentina
- Laboratorio de Neuropatología Molecular; Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis” IBCN UBA-CONICET; Buenos Aires Argentina
| | - Maria Jose Morilla
- Programa de Nanomedicinas; Departamento de Ciencia y Tecnología; Universidad Nacional de Quilmes; Bernal Argentina
| | - Alberto Javier Ramos
- Departamento de Histología, Embriología, Biología Celular y Genética; Facultad de Medicina; Universidad de Buenos Aires; Buenos Aires Argentina
- Laboratorio de Neuropatología Molecular; Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis” IBCN UBA-CONICET; Buenos Aires Argentina
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11
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Peña-Ortega F. Pharmacological Tools to Activate Microglia and their Possible use to Study Neural Network Patho-physiology. Curr Neuropharmacol 2017; 15:595-619. [PMID: 27697040 PMCID: PMC5543677 DOI: 10.2174/1570159x14666160928151546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/05/2016] [Accepted: 09/26/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Microglia are the resident immunocompetent cells of the CNS and also constitute a unique cell type that contributes to neural network homeostasis and function. Understanding microglia cell-signaling not only will reveal their diverse functions but also will help to identify pharmacological and non-pharmacological tools to modulate the activity of these cells. METHODS We undertook a search of bibliographic databases for peer-reviewed research literature to identify microglial activators and their cell-specificity. We also looked for their effects on neural network function and dysfunction. RESULTS We identified several pharmacological targets to modulate microglial function, which are more or less specific (with the proper control experiments). We also identified pharmacological targets that would require the development of new potent and specific modulators. We identified a wealth of evidence about the participation of microglia in neural network function and their alterations in pathological conditions. CONCLUSION The identification of specific microglia-activating signals provides experimental tools to modulate the activity of this heterogeneous cell type in order to evaluate its impact on other components of the nervous system, and it also helps to identify therapeutic approaches to ease some pathological conditions related to microglial dysfunction.
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Affiliation(s)
- Fernando Peña-Ortega
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, UNAM-Campus Juriquilla, México
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Eugenín J, Vecchiola A, Murgas P, Arroyo P, Cornejo F, von Bernhardi R. Expression Pattern of Scavenger Receptors and Amyloid-β Phagocytosis of Astrocytes and Microglia in Culture are Modified by Acidosis: Implications for Alzheimer’s Disease. J Alzheimers Dis 2016; 53:857-73. [DOI: 10.3233/jad-160083] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jaime Eugenín
- Laboratory of Neural Systems, Department of Biology, Faculty of Chemistry and Biology, Universidad de Santiago de Chile (USACH), Santiago, Chile
| | - Andrea Vecchiola
- Laboratory of Neuroscience, Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Endocrinology, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Paola Murgas
- Laboratory of Neuroscience, Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pablo Arroyo
- Laboratory of Neuroscience, Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Francisca Cornejo
- Laboratory of Neuroscience, Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rommy von Bernhardi
- Laboratory of Neuroscience, Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
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Cornejo F, von Bernhardi R. Age-Dependent Changes in the Activation and Regulation of Microglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:205-226. [DOI: 10.1007/978-3-319-40764-7_10] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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von Bernhardi R, Heredia F, Salgado N, Muñoz P. Microglia Function in the Normal Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:67-92. [PMID: 27714685 DOI: 10.1007/978-3-319-40764-7_4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The activation of microglia has been recognized for over a century by their morphological changes. Long slender microglia acquire a short sturdy ramified shape when activated. During the past 20 years, microglia have been accepted as an essential cellular component for understanding the pathogenic mechanism of many brain diseases, including neurodegenerative diseases. More recently, functional studies and imaging in mouse models indicate that microglia are active in the healthy central nervous system. It has become evident that microglia release several signal molecules that play key roles in the crosstalk among brain cells, i.e., astrocytes and oligodendrocytes with neurons, as well as with regulatory immune cells. Recent studies also reveal the heterogeneous nature of microglia diverse functions depending on development, previous exposure to stimulation events, brain region of residence, or pathological state. Subjects to approach by future research are still the unresolved questions regarding the conditions and mechanisms that render microglia protective, capable of preventing or reducing damage, or deleterious, capable of inducing or facilitating the progression of neuropathological diseases. This novel knowledge will certainly change our view on microglia as therapeutic target, shifting our goal from their general silencing to the generation of treatments able to change their activation pattern.
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Affiliation(s)
- Rommy von Bernhardi
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
| | - Florencia Heredia
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Nicole Salgado
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Paola Muñoz
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
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15
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von Bernhardi R, Eugenín-von Bernhardi J, Flores B, Eugenín León J. Glial Cells and Integrity of the Nervous System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:1-24. [PMID: 27714682 DOI: 10.1007/978-3-319-40764-7_1] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Today, there is enormous progress in understanding the function of glial cells, including astroglia, oligodendroglia, Schwann cells, and microglia. Around 150 years ago, glia were viewed as a glue among neurons. During the course of the twentieth century, microglia were discovered and neuroscientists' views evolved toward considering glia only as auxiliary cells of neurons. However, over the last two to three decades, glial cells' importance has been reconsidered because of the evidence on their involvement in defining central nervous system architecture, brain metabolism, the survival of neurons, development and modulation of synaptic transmission, propagation of nerve impulses, and many other physiological functions. Furthermore, increasing evidence shows that glia are involved in the mechanisms of a broad spectrum of pathologies of the nervous system, including some psychiatric diseases, epilepsy, and neurodegenerative diseases to mention a few. It appears safe to say that no neurological disease can be understood without considering neuron-glia crosstalk. Thus, this book aims to show different roles played by glia in the healthy and diseased nervous system, highlighting some of their properties while considering that the various glial cell types are essential components not only for cell function and integration among neurons, but also for the emergence of important brain homeostasis.
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Affiliation(s)
- Rommy von Bernhardi
- Department of Neurology, School of Medicine, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
| | - Jaime Eugenín-von Bernhardi
- Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Pettenkoferstr.12, 80336, Munich, Germany.,Graduate School of Systemic Neuroscience, Ludwig-Maximilians-University, 82152, Planegg-Martinsried, Munich, Germany
| | - Betsi Flores
- Department of Neurology, School of Medicine, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jaime Eugenín León
- Department of Biology, Faculty of Chemistry and Biology, USACH, Santiago, Chile
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von Bernhardi R, Cornejo F, Parada GE, Eugenín J. Role of TGFβ signaling in the pathogenesis of Alzheimer's disease. Front Cell Neurosci 2015; 9:426. [PMID: 26578886 PMCID: PMC4623426 DOI: 10.3389/fncel.2015.00426] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 10/09/2015] [Indexed: 12/19/2022] Open
Abstract
Aging is the main risk factor for Alzheimer’s disease (AD); being associated with conspicuous changes on microglia activation. Aged microglia exhibit an increased expression of cytokines, exacerbated reactivity to various stimuli, oxidative stress, and reduced phagocytosis of β-amyloid (Aβ). Whereas normal inflammation is protective, it becomes dysregulated in the presence of a persistent stimulus, or in the context of an inflammatory environment, as observed in aging. Thus, neuroinflammation can be a self-perpetuating deleterious response, becoming a source of additional injury to host cells in neurodegenerative diseases. In aged individuals, although transforming growth factor β (TGFβ) is upregulated, its canonical Smad3 signaling is greatly reduced and neuroinflammation persists. This age-related Smad3 impairment reduces protective activation while facilitating cytotoxic activation of microglia through several cellular mechanisms, potentiating microglia-mediated neurodegeneration. Here, we critically discuss the role of TGFβ-Smad signaling on the cytotoxic activation of microglia and its relevance in the pathogenesis of AD. Other protective functions, such as phagocytosis, although observed in aged animals, are not further induced by inflammatory stimuli and TGFβ1. Analysis in silico revealed that increased expression of receptor scavenger receptor (SR)-A, involved in Aβ uptake and cell activation, by microglia exposed to TGFβ, through a Smad3-dependent mechanism could be mediated by transcriptional co-factors Smad2/3 over the MSR1 gene. We discuss that changes of TGFβ-mediated regulation could at least partially mediate age-associated microglia changes, and, together with other changes on inflammatory response, could result in the reduction of protective activation and the potentiation of cytotoxicity of microglia, resulting in the promotion of neurodegenerative diseases.
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Affiliation(s)
- Rommy von Bernhardi
- Laboratory of Neuroscience, Faculty of Medicine, Department of Neurology, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Francisca Cornejo
- Laboratory of Neuroscience, Faculty of Medicine, Department of Neurology, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Guillermo E Parada
- Laboratory of Neuroscience, Faculty of Medicine, Department of Neurology, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Jaime Eugenín
- Laboratory of Neural Systems, Faculty of Chemistry and Biology, Department of Biology, Universidad de Santiago de Chile Santiago, Chile
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von Bernhardi R, Eugenín-von Bernhardi L, Eugenín J. Microglial cell dysregulation in brain aging and neurodegeneration. Front Aging Neurosci 2015; 7:124. [PMID: 26257642 PMCID: PMC4507468 DOI: 10.3389/fnagi.2015.00124] [Citation(s) in RCA: 357] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 06/22/2015] [Indexed: 12/29/2022] Open
Abstract
Aging is the main risk factor for neurodegenerative diseases. In aging, microglia undergoes phenotypic changes compatible with their activation. Glial activation can lead to neuroinflammation, which is increasingly accepted as part of the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease (AD). We hypothesize that in aging, aberrant microglia activation leads to a deleterious environment and neurodegeneration. In aged mice, microglia exhibit an increased expression of cytokines and an exacerbated inflammatory response to pathological changes. Whereas LPS increases nitric oxide (NO) secretion in microglia from young mice, induction of reactive oxygen species (ROS) predominates in older mice. Furthermore, there is accumulation of DNA oxidative damage in mitochondria of microglia during aging, and also an increased intracellular ROS production. Increased ROS activates the redox-sensitive nuclear factor kappa B, which promotes more neuroinflammation, and can be translated in functional deficits, such as cognitive impairment. Mitochondria-derived ROS and cathepsin B, are also necessary for the microglial cell production of interleukin-1β, a key inflammatory cytokine. Interestingly, whereas the regulatory cytokine TGFβ1 is also increased in the aged brain, neuroinflammation persists. Assessing this apparent contradiction, we have reported that TGFβ1 induction and activation of Smad3 signaling after inflammatory stimulation are reduced in adult mice. Other protective functions, such as phagocytosis, although observed in aged animals, become not inducible by inflammatory stimuli and TGFβ1. Here, we discuss data suggesting that mitochondrial and endolysosomal dysfunction could at least partially mediate age-associated microglial cell changes, and, together with the impairment of the TGFβ1-Smad3 pathway, could result in the reduction of protective activation and the facilitation of cytotoxic activation of microglia, resulting in the promotion of neurodegenerative diseases.
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Affiliation(s)
- Rommy von Bernhardi
- Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile Santiago, Chile
| | | | - Jaime Eugenín
- Laboratory of Neural Systems, Department of Biology, Faculty of Chemistry and Biology, Universidad de Santiago de Chile (USACH) Santiago, Chile
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18
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T Cells-Protective or Pathogenic in Alzheimer's Disease? J Neuroimmune Pharmacol 2015; 10:547-60. [PMID: 25957956 DOI: 10.1007/s11481-015-9612-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/29/2015] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia, and is characterised by deposits of amyloid β (Aβ), neurofibrillary tangles and neuronal loss. Neuroinflammatory changes have been identified as a feature of the disease, and recent studies have suggested a potential role for the peripheral immune system in driving these changes and, ultimately, the associated neuronal degeneration. A number of reports have detailed changes in the activation state and subtype of T cells in the circulation and CSF of AD patients and there is evidence of T cell infiltration into the brain. In this review, we examine the possible impact of T cell infiltration in the progression of pathology in AD and consider the data obtained from animal models of the disease. We consider how these cells infiltrate the brain, particularly in AD, and discuss whether the presence of T cells in the AD brain is protective or pathogenic. Finally we evaluate the current therapies, particularly those that involve immunization.
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Zhang H, Su YJ, Zhou WW, Wang SW, Xu PX, Yu XL, Liu RT. Activated scavenger receptor A promotes glial internalization of aβ. PLoS One 2014; 9:e94197. [PMID: 24718459 PMCID: PMC3981768 DOI: 10.1371/journal.pone.0094197] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 03/12/2014] [Indexed: 12/22/2022] Open
Abstract
Beta-amyloid (Aβ) aggregates have a pivotal role in pathological processing of Alzheimer’s disease (AD). The clearance of Aβ monomer or aggregates is a causal strategy for AD treatment. Microglia and astrocytes are the main macrophages that exert critical neuroprotective roles in the brain. They may effectively clear the toxic accumulation of Aβ at the initial stage of AD, however, their functions are attenuated because of glial overactivation. In this study, we first showed that heptapeptide XD4 activates the class A scavenger receptor (SR-A) on the glia by increasing the binding of Aβ to SR-A, thereby promoting glial phagocytosis of Aβ oligomer in microglia and astrocytes and triggering intracellular mitogen-activated protein kinase (MAPK) signaling cascades. Moreover, XD4 enhances the internalization of Aβ monomers to microglia and astrocytes through macropinocytosis or SR-A-mediated phagocytosis. Furthermore, XD4 significantly inhibits Aβ oligomer-induced cytotoxicity to glial cells and decreases the production of proinflammatory cytokines, such as TNF-α and IL-1β, in vitro and in vivo. Our findings may provide a novel strategy for AD treatment by activating SR-A.
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Affiliation(s)
- He Zhang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
- Tsinghua University School of Medicine, Haidian District, Beijing, China
| | - Ya-jing Su
- School of Life Science, Ningxia University, Yinchuan, China
| | - Wei-wei Zhou
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Shao-wei Wang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Peng-xin Xu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Xiao-lin Yu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
- * E-mail: (RTL); (XLY)
| | - Rui-tian Liu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
- * E-mail: (RTL); (XLY)
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20
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Wainaina MN, Chen Z, Zhong C. Environmental factors in the development and progression of late-onset Alzheimer's disease. Neurosci Bull 2014; 30:253-70. [PMID: 24664867 PMCID: PMC5562669 DOI: 10.1007/s12264-013-1425-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 01/23/2014] [Indexed: 01/08/2023] Open
Abstract
Late-onset Alzheimer's disease (LOAD) is an age-related neurodegenerative disorder characterized by gradual loss of synapses and neurons, but its pathogenesis remains to be clarified. Neurons live in an environment constituted by neurons themselves and glial cells. In this review, we propose that the neuronal degeneration in the AD brain is partially caused by diverse environmental factors. We first discuss various environmental stresses and the corresponding responses at different levels. Then we propose some mechanisms underlying the specific pathological changes, in particular, hypothalamic-pituitary adrenal axis dysfunction at the systemic level; cerebrovascular dysfunction, metal toxicity, glial activation, and Aβ toxicity at the intercellular level; and kinase-phosphatase imbalance and epigenetic modification at the intracellular level. Finally, we discuss the possibility of developing new strategies for the prevention and treatment of LOAD from the perspective of environmental stress. We conclude that environmental factors play a significant role in the development of LOAD through multiple pathological mechanisms.
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Affiliation(s)
- Moses N. Wainaina
- Department of Neurology, Zhongshan Hospital; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032 China
- Pwani University, Kilifi, Kenya
| | - Zhichun Chen
- Department of Neurology, Zhongshan Hospital; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032 China
| | - Chunjiu Zhong
- Department of Neurology, Zhongshan Hospital; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032 China
- Institutes of Brain Science, Fudan University, Shanghai, 200032 China
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21
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Jo WK, Law ACK, Chung SK. The neglected co-star in the dementia drama: the putative roles of astrocytes in the pathogeneses of major neurocognitive disorders. Mol Psychiatry 2014; 19:159-67. [PMID: 24393807 DOI: 10.1038/mp.2013.171] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/26/2013] [Accepted: 10/29/2013] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) and vascular dementia are the major causes of cognitive disorders worldwide. They are characterized by cognitive impairments along with neuropsychiatric symptoms, and that their pathogeneses show overlapping multifactorial mechanisms. Although AD has long been considered the most common cause of dementia, individuals afflicted with AD commonly exhibit cerebral vascular abnormalities. The concept of mixed dementia has emerged to more clearly identify patients with neurodegenerative phenomena exhibiting both AD and cerebral vascular pathologies-vascular damage along with β-amyloid (Aβ)-associated neurotoxicity and τ-hyperphosphorylation. Cognitive impairment has long been commonly explained through a 'neuro-centric' perspective, but emerging evidence has shed light over the important roles that neurovascular unit dysfunction could have in neuronal death. Moreover, accumulating data have been demonstrating astrocytes being the essential cell type in maintaining proper central nervous system functioning. In relation to dementia, the roles of astrocytes in Aβ deposition and clearance are unclear. This article emphasizes the multiple events triggered by ischemia and the cytotoxicity exerted by Aβ either alone or in association with endothelin-1 and receptor for advanced glycation end products, thereby leading to neurodegeneration in an 'astroglio-centric' perspective.
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Affiliation(s)
- W K Jo
- Neural Dysfunction Research Laboratory, Department of Psychiatry, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong
| | - A C K Law
- 1] Neural Dysfunction Research Laboratory, Department of Psychiatry, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong [2] Research Centre of Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong [3] State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong
| | - S K Chung
- 1] State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong [2] Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong
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22
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Cai Z, Hussain MD, Yan LJ. Microglia, neuroinflammation, and beta-amyloid protein in Alzheimer's disease. Int J Neurosci 2013; 124:307-21. [DOI: 10.3109/00207454.2013.833510] [Citation(s) in RCA: 320] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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