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Khan T, McFall DJ, Hussain AI, Frayser LA, Casilli TP, Steck MC, Sanchez-Brualla I, Kuehn NM, Cho M, Barnes JA, Harris BT, Vicini S, Forcelli PA. Senescent cell clearance ameliorates temporal lobe epilepsy and associated spatial memory deficits in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605784. [PMID: 39211239 PMCID: PMC11360968 DOI: 10.1101/2024.07.30.605784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Current therapies for the epilepsies only treat the symptoms, but do not prevent epileptogenesis (the process in which epilepsy develops). Many cellular responses during epileptogenesis are also common hallmarks of cellular senescence , which halts proliferation of damaged cells. Clearing senescent cells (SCs) restores function in several age-associated and neurodegenerative disease models. It is unknown whether SC accumulation contributes to epileptogenesis and associated cognitive impairments. To address this question, we used a mouse model of temporal lobe epilepsy (TLE) and characterized the senescence phenotype throughout epileptogenesis. SCs accumulated 2 weeks after SE and were predominantly microglia. We ablated SCs and reduced (and in some cases prevented) the emergence of spontaneous seizures and normalized cognitive function in mice. Suggesting that this is a translationally-relevant target we also found SC accumulation in resected hippocampi from patients with TLE. These findings indicate that SC ablation after an epileptogenic insult is a potential anti-epileptogenic therapy.
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2
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Rim C, You MJ, Nahm M, Kwon MS. Emerging role of senescent microglia in brain aging-related neurodegenerative diseases. Transl Neurodegener 2024; 13:10. [PMID: 38378788 PMCID: PMC10877780 DOI: 10.1186/s40035-024-00402-3] [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] [Accepted: 01/31/2024] [Indexed: 02/22/2024] Open
Abstract
Brain aging is a recognized risk factor for neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), but the intricate interplay between brain aging and the pathogenesis of these conditions remains inadequately understood. Cellular senescence is considered to contribute to cellular dysfunction and inflammaging. According to the threshold theory of senescent cell accumulation, the vulnerability to neurodegenerative diseases is associated with the rates of senescent cell generation and clearance within the brain. Given the role of microglia in eliminating senescent cells, the accumulation of senescent microglia may lead to the acceleration of brain aging, contributing to inflammaging and increased vulnerability to neurodegenerative diseases. In this review, we propose the idea that the senescence of microglia, which is notably vulnerable to aging, could potentially serve as a central catalyst in the progression of neurodegenerative diseases. The senescent microglia are emerging as a promising target for mitigating neurodegenerative diseases.
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Affiliation(s)
- Chan Rim
- Department of Pharmacology, Research Institute for Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Republic of Korea
| | - Min-Jung You
- Department of Pharmacology, Research Institute for Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Republic of Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Min-Soo Kwon
- Department of Pharmacology, Research Institute for Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Republic of Korea.
- Brainimmunex Inc., 26 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 13522, Republic of Korea.
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3
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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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4
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Malvaso A, Gatti A, Negro G, Calatozzolo C, Medici V, Poloni TE. Microglial Senescence and Activation in Healthy Aging and Alzheimer's Disease: Systematic Review and Neuropathological Scoring. Cells 2023; 12:2824. [PMID: 38132144 PMCID: PMC10742050 DOI: 10.3390/cells12242824] [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: 10/31/2023] [Revised: 12/07/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023] Open
Abstract
The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels" of internal and external perturbations and have long lifespans. We aim to emphasize microglial signatures in physiologic brain aging and Alzheimer's disease (AD). A systematic literature search of all published articles about microglial senescence in human healthy aging and AD was performed, searching for PubMed and Scopus online databases. Among 1947 articles screened, a total of 289 articles were assessed for full-text eligibility. Microglial transcriptomic, phenotypic, and neuropathological profiles were analyzed comprising healthy aging and AD. Our review highlights that studies on animal models only partially clarify what happens in humans. Human and mice microglia are hugely heterogeneous. Like a two-sided coin, microglia can be protective or harmful, depending on the context. Brain health depends upon a balance between the actions and reactions of microglia maintaining brain homeostasis in cooperation with other cell types (especially astrocytes and oligodendrocytes). During aging, accumulating oxidative stress and mitochondrial dysfunction weaken microglia leading to dystrophic/senescent, otherwise over-reactive, phenotype-enhancing neurodegenerative phenomena. Microglia are crucial for managing Aβ, pTAU, and damaged synapses, being pivotal in AD pathogenesis.
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Affiliation(s)
- Antonio Malvaso
- IRCCS “C. Mondino” Foundation, National Neurological Institute, Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (A.M.); (A.G.)
| | - Alberto Gatti
- IRCCS “C. Mondino” Foundation, National Neurological Institute, Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (A.M.); (A.G.)
| | - Giulia Negro
- Department of Neurology, University of Milano Bicocca, 20126 Milan, Italy;
| | - Chiara Calatozzolo
- Department of Neurology and Neuropathology, Golgi-Cenci Foundation, Abbiategrasso, 20081 Milan, Italy;
| | - Valentina Medici
- Department of Translational Medicine, University of Eastern Piedmont, 28100 Novara, Italy;
| | - Tino Emanuele Poloni
- Department of Neurology and Neuropathology, Golgi-Cenci Foundation, Abbiategrasso, 20081 Milan, Italy;
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5
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Gonzales MM, Garbarino VR, Kautz TF, Palavicini JP, Lopez-Cruzan M, Dehkordi SK, Mathews JJ, Zare H, Xu P, Zhang B, Franklin C, Habes M, Craft S, Petersen RC, Tchkonia T, Kirkland JL, Salardini A, Seshadri S, Musi N, Orr ME. Senolytic therapy in mild Alzheimer's disease: a phase 1 feasibility trial. Nat Med 2023; 29:2481-2488. [PMID: 37679434 PMCID: PMC10875739 DOI: 10.1038/s41591-023-02543-w] [Citation(s) in RCA: 47] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 08/14/2023] [Indexed: 09/09/2023]
Abstract
Cellular senescence contributes to Alzheimer's disease (AD) pathogenesis. An open-label, proof-of-concept, phase I clinical trial of orally delivered senolytic therapy, dasatinib (D) and quercetin (Q), was conducted in early-stage symptomatic patients with AD to assess central nervous system (CNS) penetrance, safety, feasibility and efficacy. Five participants (mean age = 76 + 5 years; 40% female) completed the 12-week pilot study. D and Q levels in blood increased in all participants (12.7-73.5 ng ml-1 for D and 3.29-26.3 ng ml-1 for Q). In cerebrospinal fluid (CSF), D levels were detected in four participants (80%) ranging from 0.281 to 0.536 ml-1 with a CSF to plasma ratio of 0.422-0.919%; Q was not detected. The treatment was well-tolerated, with no early discontinuation. Secondary cognitive and neuroimaging endpoints did not significantly differ from baseline to post-treatment further supporting a favorable safety profile. CSF levels of interleukin-6 (IL-6) and glial fibrillary acidic protein (GFAP) increased (t(4) = 3.913, P = 0.008 and t(4) = 3.354, P = 0.028, respectively) with trending decreases in senescence-related cytokines and chemokines, and a trend toward higher Aβ42 levels (t(4) = -2.338, P = 0.079). In summary, CNS penetrance of D was observed with outcomes supporting safety, tolerability and feasibility in patients with AD. Biomarker data provided mechanistic insights of senolytic effects that need to be confirmed in fully powered, placebo-controlled studies. ClinicalTrials.gov identifier: NCT04063124 .
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Affiliation(s)
- Mitzi M Gonzales
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Department of Neurology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
| | - Valentina R Garbarino
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Tiffany F Kautz
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Juan Pablo Palavicini
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Marisa Lopez-Cruzan
- Department of Psychiatry & Behavioral Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Shiva Kazempour Dehkordi
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Julia J Mathews
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Habil Zare
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Peng Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
- Mount Sinai Center for Transformative Disease Modeling, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Bin Zhang
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
- Mount Sinai Center for Transformative Disease Modeling, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Crystal Franklin
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Mohamad Habes
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Neuroimage Analytics Laboratory and Biggs Institute Neuroimaging Core, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Suzanne Craft
- Department of Internal Medicine Section on Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | | | - Tamara Tchkonia
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - James L Kirkland
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
- Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Arash Salardini
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Neurology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sudha Seshadri
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Neurology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Nicolas Musi
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Miranda E Orr
- Department of Internal Medicine Section on Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
- Salisbury VA Medical Center, Salisbury, NC, USA.
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6
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Neumann P, Lenz DE, Streit WJ, Bechmann I. Is microglial dystrophy a form of cellular senescence? An analysis of senescence markers in the aged human brain. Glia 2023; 71:377-390. [PMID: 36286188 DOI: 10.1002/glia.24282] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/27/2022] [Accepted: 09/30/2022] [Indexed: 01/08/2023]
Abstract
Aging can cause morphological transformation in human microglia indicative of cell senescence, termed microglial dystrophy. However, cellular senescence is characterized by additional changes, such as an irregular cell cycle arrest, and a variety of metabolic and molecular changes including a senescence-associated secretory phenotype, dysfunction of degradation mechanisms, and altered DNA damage response. Here, we tested whether dystrophic microglia display customary markers of cell senescence by performing double and triple staining in sections of the temporal lobe and brain stem from 14 humans. We found that markers related to oxidative damage, such as upregulation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), hemeoxygenase-1 (HO-1), and y-H2AX, as well as inclusion of lipofuscin, do not or only exceptionally colocalize with dystrophic microglia. Further, we did not observe a decline in lamin B1 around nuclear laminae in either dystrophic or ramified microglia within the same microscopic field. Only ferritin expression, which is known to increase with aging in CNS microglia, was frequently observed in dystrophic, but rarely in ramified microglial cells. We conclude that neither dystrophic nor ramified microglia in human brain exhibit significant expression of conventional senescence markers associated with oxidative stress, and that ferritin is the dominant immunophenotypic change related to microglial aging. We suggest that multiple pathogenic mechanisms other than those driving cellular senescence contribute to dystrophic transformation of microglia.
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Affiliation(s)
| | - Dana E Lenz
- Institute of Anatomy, Universität Leipzig, Leipzig, Germany
| | - Wolfgang J Streit
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Ingo Bechmann
- Institute of Anatomy, Universität Leipzig, Leipzig, Germany
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7
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Gonzales MM, Garbarino VR, Pollet E, Palavicini JP, Kellogg DL, Kraig E, Orr ME. Biological aging processes underlying cognitive decline and neurodegenerative disease. J Clin Invest 2022; 132:e158453. [PMID: 35575089 PMCID: PMC9106343 DOI: 10.1172/jci158453] [Citation(s) in RCA: 71] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease and related dementias (ADRD) are among the top contributors to disability and mortality in later life. As with many chronic conditions, aging is the single most influential factor in the development of ADRD. Even among older adults who remain free of dementia throughout their lives, cognitive decline and neurodegenerative changes are appreciable with advancing age, suggesting shared pathophysiological mechanisms. In this Review, we provide an overview of changes in cognition, brain morphology, and neuropathological protein accumulation across the lifespan in humans, with complementary and mechanistic evidence from animal models. Next, we highlight selected aging processes that are differentially regulated in neurodegenerative disease, including aberrant autophagy, mitochondrial dysfunction, cellular senescence, epigenetic changes, cerebrovascular dysfunction, inflammation, and lipid dysregulation. We summarize research across clinical and translational studies to link biological aging processes to underlying ADRD pathogenesis. Targeting fundamental processes underlying biological aging may represent a yet relatively unexplored avenue to attenuate both age-related cognitive decline and ADRD. Collaboration across the fields of geroscience and neuroscience, coupled with the development of new translational animal models that more closely align with human disease processes, is necessary to advance novel therapeutic discovery in this realm.
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Affiliation(s)
- Mitzi M. Gonzales
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases
- Department of Neurology
| | | | - Erin Pollet
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases
| | - Juan P. Palavicini
- Barshop Institute for Longevity and Aging Studies, and
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Dean L. Kellogg
- Barshop Institute for Longevity and Aging Studies, and
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- Geriatric Research and Education Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
| | - Ellen Kraig
- Barshop Institute for Longevity and Aging Studies, and
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Miranda E. Orr
- Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
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8
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Linard M, Ravier A, Mougué L, Grgurina I, Boutillier AL, Foubert-Samier A, Blanc F, Helmer C. Infectious Agents as Potential Drivers of α-Synucleinopathies. Mov Disord 2022; 37:464-477. [PMID: 35040520 DOI: 10.1002/mds.28925] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/10/2021] [Accepted: 12/27/2021] [Indexed: 12/16/2022] Open
Abstract
α-synucleinopathies, encompassing Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, are devastating neurodegenerative diseases for which available therapeutic options are scarce, mostly because of our limited understanding of their pathophysiology. Although these pathologies are attributed to an intracellular accumulation of the α-synuclein protein in the nervous system with subsequent neuronal loss, the trigger(s) of this accumulation is/are not clearly identified. Among the existing hypotheses, interest in the hypothesis advocating the involvement of infectious agents in the onset of these diseases is renewed. In this article, we aimed to review the ongoing relevant factors favoring and opposing this hypothesis, focusing on (1) the potential antimicrobial role of α-synuclein, (2) potential entry points of pathogens in regard to early symptoms of diverse α-synucleinopathies, (3) pre-existing literature reviews assessing potential associations between infectious agents and Parkinson's disease, (4) original studies assessing these associations for dementia with Lewy bodies and multiple system atrophy (identified through a systematic literature review), and finally (5) potential susceptibility factors modulating the effects of infectious agents on the nervous system. © 2022 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Morgane Linard
- University of Bordeaux, INSERM, Bordeaux Population Health Research Center, UMR U1219, Bordeaux, France
| | - Alix Ravier
- CM2R (Memory Resource and Research Centre), Geriatrics Department, University Hospitals of Strasbourg, Strasbourg, France
| | - Louisa Mougué
- Cognitive-Behavioral Unit and Memory Consultations, Hospital of Sens, Sens, France
| | - Iris Grgurina
- University of Strasbourg, UMR7364 CNRS, LNCA, Strasbourg, France
| | | | - Alexandra Foubert-Samier
- University of Bordeaux, INSERM, Bordeaux Population Health Research Center, UMR U1219, Bordeaux, France.,French Reference Centre for MSA, University Hospital of Bordeaux, Bordeaux, France
| | - Frédéric Blanc
- CM2R (Memory Resource and Research Centre), Geriatrics Department, University Hospitals of Strasbourg, Strasbourg, France.,ICube Laboratory and FMTS (Fédération de Médecine Translationnelle de Strasbourg), Team IMIS, University of Strasbourg, Strasbourg, France
| | - Catherine Helmer
- University of Bordeaux, INSERM, Bordeaux Population Health Research Center, UMR U1219, Bordeaux, France
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9
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Linard M, Bezin J, Hucteau E, Joly P, Garrigue I, Dartigues JF, Pariente A, Helmer C. Antiherpetic drugs: a potential way to prevent Alzheimer's disease? Alzheimers Res Ther 2022; 14:3. [PMID: 34996520 PMCID: PMC8742322 DOI: 10.1186/s13195-021-00950-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 12/15/2021] [Indexed: 12/23/2022]
Abstract
Background Considering the growing body of evidence suggesting a potential implication of herpesviruses in the development of dementia, several authors have questioned a protective effect of antiherpetic drugs (AHDs) which may represent a new means of prevention, well tolerated and easily accessible. Subsequently, several epidemiological studies have shown a reduction in the risk of dementia in subjects treated with AHDs, but the biological plausibility of this association and the impact of potential methodological biases need to be discussed in more depth. Methods Using a French medico-administrative database, we assessed the association between the intake of systemic AHDs and the incidence of (i) dementia, (ii) Alzheimer’s disease (AD), and (iii) vascular dementia in 68,291 subjects over 65 who were followed between 2009 and 2017. Regarding potential methodological biases, Cox models were adjusted for numerous potential confounding factors (including proxies of sociodemographic status, comorbidities, and use of healthcare) and sensitivity analyses were performed in an attempt to limit the risk of indication and reverse causality biases. Results 9.7% of subjects (n=6642) had at least one intake of systemic AHD, and 8883 incident cases of dementia were identified. Intake of at least one systemic AHD during follow-up was significantly associated with a decreased risk of AD (aHR 0.85 95% confidence interval [0.75–0.96], p=0.009) and, to a lesser extent with respect to p values, to both dementia from any cause and vascular dementia. The association with AD remained significant in sensitivity analyses. The number of subjects with a regular intake was low and prevented us from studying its association with dementia. Conclusions Taking at least one systemic AHD during follow-up was significantly associated with a 15% reduced risk of developing AD, even after taking into account several potential methodological biases. Nevertheless, the low frequency of subjects with a regular intake questions the biological plausibility of this association and highlights the limits of epidemiological data to evaluate a potential protective effect of a regular treatment by systemic AHDs on the incidence of dementia Supplementary Information The online version contains supplementary material available at 10.1186/s13195-021-00950-0.
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Affiliation(s)
- Morgane Linard
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France.
| | - Julien Bezin
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France.,Pharmacology Department, Bordeaux University Hospital, F-33076, Bordeaux, France
| | - Emilie Hucteau
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France
| | - Pierre Joly
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France
| | - Isabelle Garrigue
- Virology Department, Bordeaux University Hospital and University of Bordeaux, CNRS-UMR 5234, F-33000, Bordeaux, France
| | - Jean-François Dartigues
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France.,Memory Consultation, CMRR, Bordeaux University Hospital, F-33076, Bordeaux, France
| | - Antoine Pariente
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France.,Pharmacology Department, Bordeaux University Hospital, F-33076, Bordeaux, France
| | - Catherine Helmer
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR U1219, F-33000, Bordeaux, France
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10
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Yoo HJ, Kwon MS. Aged Microglia in Neurodegenerative Diseases: Microglia Lifespan and Culture Methods. Front Aging Neurosci 2022; 13:766267. [PMID: 35069173 PMCID: PMC8766407 DOI: 10.3389/fnagi.2021.766267] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 12/06/2021] [Indexed: 12/20/2022] Open
Abstract
Microglia have been recognized as macrophages of the central nervous system (CNS) that are regarded as a culprit of neuroinflammation in neurodegenerative diseases. Thus, microglia have been considered as a cell that should be suppressed for maintaining a homeostatic CNS environment. However, microglia ontogeny, fate, heterogeneity, and their function in health and disease have been defined better with advances in single-cell and imaging technologies, and how to maintain homeostatic microglial function has become an emerging issue for targeting neurodegenerative diseases. Microglia are long-lived cells of yolk sac origin and have limited repopulating capacity. So, microglial perturbation in their lifespan is associated with not only neurodevelopmental disorders but also neurodegenerative diseases with aging. Considering that microglia are long-lived cells and may lose their functional capacity as they age, we can expect that aged microglia contribute to various neurodegenerative diseases. Thus, understanding microglial development and aging may represent an opportunity for clarifying CNS disease mechanisms and developing novel therapies.
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Affiliation(s)
- Hyun-Jung Yoo
- Department of Pharmacology, School of Medicine, Research Institute for Basic Medical Science, CHA University, Cha Bio Complex, Seongnam-si, South Korea
- Research Competency Milestones Program (RECOMP) of School of Medicine, CHA University, Seongnam-si, South Korea
| | - Min-Soo Kwon
- Department of Pharmacology, School of Medicine, Research Institute for Basic Medical Science, CHA University, Cha Bio Complex, Seongnam-si, South Korea
- *Correspondence: Min-Soo Kwon,
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11
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Yuan M, Wang Y, Wang S, Huang Z, Jin F, Zou Q, Li J, Pu Y, Cai Z. Bioenergetic Impairment in the Neuro-Glia-Vascular Unit: An Emerging Physiopathology during Aging. Aging Dis 2021; 12:2080-2095. [PMID: 34881087 PMCID: PMC8612602 DOI: 10.14336/ad.2021.04017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 04/17/2021] [Indexed: 12/28/2022] Open
Abstract
An emerging concept termed the "neuro-glia-vascular unit" (NGVU) has been established in recent years to understand the complicated mechanism of multicellular interactions among vascular cells, glial cells, and neurons. It has been proverbially reported that the NGVU is significantly associated with neurodegenerative disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Physiological aging is an inevitable progression associated with oxidative damage, bioenergetic alterations, mitochondrial dysfunction, and neuroinflammation, which is partially similar to the pathology of AD. Thus, senescence is regarded as the background for the development of neurodegenerative diseases. With the exacerbation of global aging, senescence is an increasingly serious problem in the medical field. In this review, the coupling of each component, including neurons, glial cells, and vascular cells, in the NGVU is described in detail. Then, various mechanisms of age-dependent impairment in each part of the NGVU are discussed. Moreover, the potential bioenergetic alterations between different cell types in the NGVU are highlighted, which seems to be an emerging physiopathology associated with the aged brain. Bioenergetic intervention in the NGVU may be a new direction for studies on delaying or diminishing aging in the future.
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Affiliation(s)
- Minghao Yuan
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,2Chongqing School, University of Chinese Academy of Sciences, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China.,4Chongqing Medical University, Chongqing, China
| | - Yangyang Wang
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China
| | - Shengyuan Wang
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,2Chongqing School, University of Chinese Academy of Sciences, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China.,4Chongqing Medical University, Chongqing, China
| | - Zhenting Huang
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China
| | - Feng Jin
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,2Chongqing School, University of Chinese Academy of Sciences, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China
| | - Qian Zou
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China
| | - Jing Li
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China
| | - Yinshuang Pu
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China
| | - Zhiyou Cai
- 1Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, 400013, Chongqing, China.,2Chongqing School, University of Chinese Academy of Sciences, Chongqing, China.,3Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing, 400013, Chongqing, China.,4Chongqing Medical University, Chongqing, China
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12
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Gonzales MM, Krishnamurthy S, Garbarino V, Daeihagh AS, Gillispie GJ, Deep G, Craft S, Orr ME. A geroscience motivated approach to treat Alzheimer's disease: Senolytics move to clinical trials. Mech Ageing Dev 2021; 200:111589. [PMID: 34687726 PMCID: PMC9059898 DOI: 10.1016/j.mad.2021.111589] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/04/2021] [Accepted: 10/18/2021] [Indexed: 12/29/2022]
Abstract
The pathogenic processes driving Alzheimer's disease (AD) are complex. An incomplete understanding of underlying disease mechanisms has presented insurmountable obstacles for developing effective disease-modifying therapies. Advanced chronological age is the greatest risk factor for developing AD. Intervening on biological aging may alter disease progression and represents a novel, complementary approach to current strategies. Toward this end, cellular senescence has emerged as a promising target. This complex stress response harbors damaged cells in a cell cycle arrested, apoptosis-resistant cell state. Senescent cells accumulate with age where they notoriously secrete molecules that contribute to chronic tissue dysfunction and disease. Thus, benefits of cell survival in a senescent fate are countered by their toxic secretome. The removal of senescent cells improves brain structure and function in rodent models at risk of developing AD, and in those with advanced Aβ and tau pathology. The present review describes the path to translating this promising treatment strategy to AD clinical trials. We review evidence for senescent cell accumulation in the human brain, considerations and strategies for senescence-targeting trials specific to AD, approaches to detect senescent brain cells in biofluids, and summarize the goals of the first senolytic trials for the treatment of AD (NCT04063124 and NCT04685590). This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.
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Affiliation(s)
- Mitzi M Gonzales
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sudarshan Krishnamurthy
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; Bowman Gray Center for Medical Education, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Valentina Garbarino
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Ali S Daeihagh
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Gregory J Gillispie
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Gagan Deep
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Suzanne Craft
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Miranda E Orr
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA; Salisbury VA Medical Center, Salisbury, NC, USA.
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13
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Gonzales MM, Krishnamurthy S, Garbarino V, Daeihagh AS, Gillispie GJ, Deep G, Craft S, Orr ME. A geroscience motivated approach to treat Alzheimer’s disease: Senolytics move to clinical trials. Mech Ageing Dev 2021. [DOI: 10.1016/j.mad.2021.111589
expr 868687188 + 807217478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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14
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Sun M, Bao W, Huang C, Xia Z, Zhang C, Wang G, Wang R, Li J, Roux S, Li Q, Zou D, Ma K, Bao X. A Novel Probiotic Formula, BIOCG, Protects Against Alzheimer's-Related Cognitive Deficits via Regulation of Dendritic Spine Dynamics. Curr Alzheimer Res 2021; 18:558-572. [PMID: 34674621 DOI: 10.2174/1567205018666211022091110] [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: 01/27/2021] [Revised: 06/27/2021] [Accepted: 08/23/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND The brain-gut-microbiome axis has emerged as an important pathway through which perturbations in the gut and/or microbial microenvironment can impact neurological function. Such alterations have been implicated in a variety of neuropsychiatric disorders, includ- ing depression, anxiety, and Alzheimer's Disease (AD) and the use of probiotics as therapy for th- ese diseases remains promising. However, the mechanisms underlying the gut microenvironment's influence on disease pathogenesis and therapy remain unclear. OBJECTIVE The objective of this study is to investigate the effect of a novel probiotic formula, BIOCG, on cognitive function and pathobiological mechanisms, including amyloid processing and dendritic spine dynamics, in a mouse model of AD. METHODS BIOCG was administered for 3 months to 3xTg or 3xTg; Thy1-YFP AD mice and func- tional outcomes were assessed via behavioral testing and electrophysiology. Mechanisms relevant to AD pathogenesis including dendritic spine morphology and turnover, Amyloid Precursor Pro- tein (APP) processing and microglial phenotype were also evaluated. Finally, we sequenced fecal samples following probiotic treatment to assess the impact on gut microbial composition and corre- late the changes with the above described measures. RESULTS Mice treated with BIOCG demonstrated preserved cognitive abilities and stronger Long- Term Potentiation (LTP), spontaneous Excitatory Postsynaptic Currents (sEPSC), and glutamate-in- duced LTPs, indicative of functional and electrophysiological effects. Moreover, we observed atten- uated AD pathogenesis, including reduced Amyloid Beta (Aβ) burden, as well as more mature den- dritic spines in the BIOCG-treated. Our finding of changes in microglial number and phenotype in the treatment group suggests that this formulation may mediate its effects via attenuation of neu- roinflammation. Sequencing data confirmed that the gut microbiome in treated mice was more varied and harbored a greater proportion of "beneficial" bacteria. CONCLUSION Overall, our results indicate that treatment with BIOCG enhances microbial diversity and, through gut-brain axis interactions, attenuates neuroinflammation to produce histologic and functional improvement in AD pathogenesis.
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Affiliation(s)
- Miao Sun
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu. China
| | - Wenchenyang Bao
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu. China
| | - Chengyu Huang
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu. China
| | - Ziyue Xia
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu. China
| | - Changliang Zhang
- Jiangsu Biodep Biotechnology, 6-C2 Dongsheng West Road, Jiangyin 214400, Jiangsu. China
| | - Guangxian Wang
- Jiangsu Biodep Biotechnology, 6-C2 Dongsheng West Road, Jiangyin 214400, Jiangsu. China
| | - Runxin Wang
- Jiangsu Biodep Biotechnology, 6-C2 Dongsheng West Road, Jiangyin 214400, Jiangsu. China
| | - Jiangyu Li
- Admera Health, South Plainfield, NJ07080. United States
| | - Shaun Roux
- Probiotics Australia, 24-30 Blanck Street, Ormeau, QLD, 4208. Australia
| | - Qian Li
- Department of biology, College of Staten Island, Staten Island, NY 10314 . United States
| | - Dongmei Zou
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu. China
| | - Kai Ma
- Jiangsu Biodep Biotechnology, 6-C2 Dongsheng West Road, Jiangyin 214400, Jiangsu. China
| | - Xiaofeng Bao
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu. China
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15
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Chee SEJ, Solito E. The Impact of Ageing on the CNS Immune Response in Alzheimer's Disease. Front Immunol 2021; 12:738511. [PMID: 34603320 PMCID: PMC8484764 DOI: 10.3389/fimmu.2021.738511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/01/2021] [Indexed: 12/25/2022] Open
Abstract
Alzheimer's Disease (AD) is a progressive neurodegenerative disease strongly associated with increasing age. Neuroinflammation and the accumulation of amyloid protein are amongst the hallmarks of this disease and most translational research to date has focused on targeting these two processes. However, the exact etiology of AD remains to be fully elucidated. When compared alongside, the immune response in AD closely resembles the central nervous system (CNS) immune changes seen in elderly individuals. It is possible that AD is a pathological consequence of an aged immune system secondary to chronic stimulation by a previous or ongoing insult. Pathological changes like amyloid accumulation and neuronal cell death may reflect this process of immunosenescence as the CNS immune system fails to maintain homeostasis in the CNS. It is likely that future treatments designed to modulate the aged immune system may prove beneficial in altering the disease course. The development of new tests for appropriate biomarkers would also be essential in screening for patients most likely to benefit from such treatments.
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Affiliation(s)
- Stephan En Jie Chee
- Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Egle Solito
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Federico II University, Naples, Italy
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16
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Murdock BJ, Famie JP, Piecuch CE, Pawlowski KD, Mendelson FE, Pieroni CH, Iniguez SD, Zhao L, Goutman SA, Feldman EL. NK cells associate with ALS in a sex- and age-dependent manner. JCI Insight 2021; 6:147129. [PMID: 33974561 PMCID: PMC8262328 DOI: 10.1172/jci.insight.147129] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 05/05/2021] [Indexed: 12/11/2022] Open
Abstract
NK cells are innate immune cells implicated in ALS; whether NK cells impact ALS in a sex- and age-specific manner was investigated. Herein, NK cells were depleted in male and female SOD1G93A ALS mice, survival and neuroinflammation were assessed, and data were stratified by sex. NK cell depletion extended survival in female but not male ALS mice with sex-specific effects on spinal cord microglia. In humans, NK cell numbers, NK cell subpopulations, and NK cell surface markers were examined in prospectively blood collected from subjects with ALS and control subjects; longitudinal changes in these metrics were correlated to revised ALS functional rating scale (ALSFRS-R) slope and stratified by sex and age. Expression of NK cell trafficking and cytotoxicity markers was elevated in subjects with ALS, and changes in CXCR3+ NK cells and 7 trafficking and cytotoxicity markers (CD11a, CD11b, CD38, CX3CR1, NKG2D, NKp30, NKp46) correlated with disease progression. Age affected the associations between ALSFRS-R and markers NKG2D and NKp46, whereas sex impacted the NKp30 association. Collectively, these findings suggest that NK cells contribute to ALS progression in a sex- and age-specific manner and demonstrate that age and sex are critical variables when designing and assessing ALS immunotherapy.
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Affiliation(s)
| | | | | | | | | | | | | | - Lili Zhao
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
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17
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Microglia in Neurodegenerative Events-An Initiator or a Significant Other? Int J Mol Sci 2021; 22:ijms22115818. [PMID: 34072307 PMCID: PMC8199265 DOI: 10.3390/ijms22115818] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/22/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023] Open
Abstract
A change in microglia structure, signaling, or function is commonly associated with neurodegeneration. This is evident in the patient population, animal models, and targeted in vitro assays. While there is a clear association, it is not evident that microglia serve as an initiator of neurodegeneration. Rather, the dynamics imply a close interaction between the various cell types and structures in the brain that orchestrate the injury and repair responses. Communication between microglia and neurons contributes to the physiological phenotype of microglia maintaining cells in a surveillance state and allows the cells to respond to events occurring in their environment. Interactions between microglia and astrocytes is not as well characterized, nor are interactions with other members of the neurovascular unit; however, given the influence of systemic factors on neuroinflammation and disease progression, such interactions likely represent significant contributes to any neurodegenerative process. In addition, they offer multiple target sites/processes by which environmental exposures could contribute to neurodegenerative disease. Thus, microglia at least play a role as a significant other with an equal partnership; however, claiming a role as an initiator of neurodegeneration remains somewhat controversial.
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18
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Morgan DG, Mielke MM. Knowledge gaps in Alzheimer's disease immune biomarker research. Alzheimers Dement 2021; 17:2030-2042. [PMID: 33984178 DOI: 10.1002/alz.12342] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 11/09/2022]
Abstract
Considerable evidence has accumulated implicating a role for immune mechanisms in moderating the pathology in Alzheimer's disease dementia. However, the appropriate therapeutic target, the appropriate direction of manipulation, and the stage of disease at which to begin treatment remain unanswered questions. Part of the challenge derives from the absence of any selective pressure to develop a coordinated beneficial immune response to severe neural injury in adults. Thus, immune responses to the prevailing stimuli are likely to contain both beneficial and detrimental components. Knowledge gaps include: (1) how a biomarker change relates to the underlying biology, (2) the degree to which pathological stage group differences reflect a response to pathology versus trait differences among individuals regulating risk of developing pathology, (3) the degree to which biomarker levels are predictive of subsequent changes in pathology and/or cognition, and (4) experimental manipulations in model systems to determine whether differences in immune biomarkers are causally related to pathology.
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Affiliation(s)
- David G Morgan
- Alzheimer's Alliance, Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, Michigan, USA
| | - Michelle M Mielke
- Division of Epidemiology, Department of Health Sciences Research, Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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19
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Al Hussein Al Awamlh S, Wareham LK, Risner ML, Calkins DJ. Insulin Signaling as a Therapeutic Target in Glaucomatous Neurodegeneration. Int J Mol Sci 2021; 22:4672. [PMID: 33925119 PMCID: PMC8124776 DOI: 10.3390/ijms22094672] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 04/24/2021] [Accepted: 04/27/2021] [Indexed: 01/28/2023] Open
Abstract
Glaucoma is a multifactorial disease that is conventionally managed with treatments to lower intraocular pressure (IOP). Despite these efforts, many patients continue to lose their vision. The degeneration of retinal ganglion cells (RGCs) and their axons in the optic tract that characterizes glaucoma is similar to neurodegeneration in other age-related disorders of the central nervous system (CNS). Identifying the different molecular signaling pathways that contribute to early neuronal dysfunction can be utilized for neuroprotective strategies that prevent degeneration. The discovery of insulin and its receptor in the CNS and retina led to exploration of the role of insulin signaling in the CNS. Historically, insulin was considered a peripherally secreted hormone that regulated glucose homeostasis, with no obvious roles in the CNS. However, a growing number of pre-clinical and clinical studies have demonstrated the potential of modulating insulin signaling in the treatment of neurodegenerative diseases. This review will highlight the role that insulin signaling plays in RGC neurodegeneration. We will focus on how this pathway can be therapeutically targeted to promote RGC axon survival and preserve vision.
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Affiliation(s)
- Sara Al Hussein Al Awamlh
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (S.A.H.A.A.); (L.K.W.); (M.L.R.)
| | - Lauren K. Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (S.A.H.A.A.); (L.K.W.); (M.L.R.)
| | - Michael L. Risner
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (S.A.H.A.A.); (L.K.W.); (M.L.R.)
| | - David J. Calkins
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (S.A.H.A.A.); (L.K.W.); (M.L.R.)
- Department of Ophthalmology & Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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20
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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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21
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Microglia in Prion Diseases: Angels or Demons? Int J Mol Sci 2020; 21:ijms21207765. [PMID: 33092220 PMCID: PMC7589037 DOI: 10.3390/ijms21207765] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/16/2020] [Accepted: 10/16/2020] [Indexed: 02/08/2023] Open
Abstract
Prion diseases are rare transmissible neurodegenerative disorders caused by the accumulation of a misfolded isoform (PrPSc) of the cellular prion protein (PrPC) in the central nervous system (CNS). Neuropathological hallmarks of prion diseases are neuronal loss, astrogliosis, and enhanced microglial proliferation and activation. As immune cells of the CNS, microglia participate both in the maintenance of the normal brain physiology and in driving the neuroinflammatory response to acute or chronic (e.g., neurodegenerative disorders) insults. Microglia involvement in prion diseases, however, is far from being clearly understood. During this review, we summarize and discuss controversial findings, both in patient and animal models, suggesting a neuroprotective role of microglia in prion disease pathogenesis and progression, or—conversely—a microglia-mediated exacerbation of neurotoxicity in later stages of disease. We also will consider the active participation of PrPC in microglial functions, by discussing previous reports, but also by presenting unpublished results that support a role for PrPC in cytokine secretion by activated primary microglia.
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22
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Bachmann MC, Bellalta S, Basoalto R, Gómez-Valenzuela F, Jalil Y, Lépez M, Matamoros A, von Bernhardi R. The Challenge by Multiple Environmental and Biological Factors Induce Inflammation in Aging: Their Role in the Promotion of Chronic Disease. Front Immunol 2020; 11:570083. [PMID: 33162985 PMCID: PMC7591463 DOI: 10.3389/fimmu.2020.570083] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 09/24/2020] [Indexed: 12/13/2022] Open
Abstract
The aging process is driven by multiple mechanisms that lead to changes in energy production, oxidative stress, homeostatic dysregulation and eventually to loss of functionality and increased disease susceptibility. Most aged individuals develop chronic low-grade inflammation, which is an important risk factor for morbidity, physical and cognitive impairment, frailty, and death. At any age, chronic inflammatory diseases are major causes of morbimortality, affecting up to 5-8% of the population of industrialized countries. Several environmental factors can play an important role for modifying the inflammatory state. Genetics accounts for only a small fraction of chronic-inflammatory diseases, whereas environmental factors appear to participate, either with a causative or a promotional role in 50% to 75% of patients. Several of those changes depend on epigenetic changes that will further modify the individual response to additional stimuli. The interaction between inflammation and the environment offers important insights on aging and health. These conditions, often depending on the individual's sex, appear to lead to decreased longevity and physical and cognitive decline. In addition to biological factors, the environment is also involved in the generation of psychological and social context leading to stress. Poor psychological environments and other sources of stress also result in increased inflammation. However, the mechanisms underlying the role of environmental and psychosocial factors and nutrition on the regulation of inflammation, and how the response elicited for those factors interact among them, are poorly understood. Whereas certain deleterious environmental factors result in the generation of oxidative stress driven by an increased production of reactive oxygen and nitrogen species, endoplasmic reticulum stress, and inflammation, other factors, including nutrition (polyunsaturated fatty acids) and behavioral factors (exercise) confer protection against inflammation, oxidative and endoplasmic reticulum stress, and thus ameliorate their deleterious effect. Here, we discuss processes and mechanisms of inflammation associated with environmental factors and behavior, their links to sex and gender, and their overall impact on aging.
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Affiliation(s)
| | - Sofía Bellalta
- School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Roque Basoalto
- School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Yorschua Jalil
- School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Macarena Lépez
- School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Anibal Matamoros
- School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.,Institute of Biological Sciences (ICB), Federal University of Pará, Belem, Brazil
| | - Rommy von Bernhardi
- School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
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Omer A, Patel D, Moran JL, Lian XJ, Di Marco S, Gallouzi IE. Autophagy and heat-shock response impair stress granule assembly during cellular senescence. Mech Ageing Dev 2020; 192:111382. [PMID: 33049246 DOI: 10.1016/j.mad.2020.111382] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/21/2020] [Accepted: 10/05/2020] [Indexed: 01/08/2023]
Abstract
Stress granules (SGs) are membraneless organelles formed in response to insult. These granules are related to pathological granules found in age-related neurogenerative diseases such as Parkinson's and Alzheimer's. Previously, we demonstrated that senescent cells, which accumulate with age, exposed to chronic oxidative stress, are unable to form SGs. Here, we show that the senescent cells' inability to form SGs correlates with an upregulation in both the heat-shock response and autophagy pathways, both of which are well-established promoters of SG disassembly. Our data also reveals that the knockdown of HSP70 and ATG5, important components of the heat-shock response and autophagy pathways, respectively, restores the number of SGs formed in senescent cells exposed to chronic oxidative stress. Surprisingly, under these conditions, the depletion of HSP70 or ATG5 did not affect the clearance of these SGs during their recovery from chronic stress. These data reveal that senescent cells possess a unique heat-shock and autophagy-dependent ability to impair the formation of SGs in response to chronic stress, thereby expanding the existing understanding of SG dynamics in senescent cells and their potential contribution to age-related neurodegenerative diseases.
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Affiliation(s)
- Amr Omer
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada.
| | - Devang Patel
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Julian Lucas Moran
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Xian Jin Lian
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Sergio Di Marco
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Imed-Eddine Gallouzi
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada.
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24
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A Unifying Hypothesis for Alzheimer's Disease: From Plaques to Neurodegeneration. Trends Neurosci 2020; 42:310-322. [PMID: 31006494 DOI: 10.1016/j.tins.2019.03.003] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 12/21/2022]
Abstract
Evidence suggests that amyloid β is highly toxic to synapses in a phospho-Tau-dependent manner. Here, I present a hypothesis that links previous evidence from the first rise of amyloid β through to Tau tangles and neurodegeneration. In the immediate vicinity of plaques, concentrated soluble amyloid β occurs in equilibrium with deposited forms. Initially, plaques cover only a small percentage of brain volume. Microglia, by efficiently removing damaged synapses, may prevent spread of damage along the axon, restricting damage to the immediate vicinity of plaques. However, as plaque load increases, as seen in Alzheimer's disease, an individual axon may suffer multiple points of damage, leading to dissociation of Tau, formation of a tangle, and loss of the axon. As more axons suffer this fate, the network eventually degenerates. According to this hypothesis, the degree of plaque load that an individual can tolerate would depend on the efficiency of their microglia in removing amyloid-β-damaged synapses and the distribution of plaques, relative to axon trajectories, would determine the eventual cognitive symptoms.
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25
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Vanhunsel S, Beckers A, Moons L. Designing neuroreparative strategies using aged regenerating animal models. Ageing Res Rev 2020; 62:101086. [PMID: 32492480 DOI: 10.1016/j.arr.2020.101086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 04/13/2020] [Accepted: 05/08/2020] [Indexed: 12/13/2022]
Abstract
In our ever-aging world population, the risk of age-related neuropathies has been increasing, representing both a social and economic burden to society. Since the ability to regenerate in the adult mammalian central nervous system is very limited, brain trauma and neurodegeneration are often permanent. As a consequence, novel scientific challenges have emerged and many research efforts currently focus on triggering repair in the damaged or diseased brain. Nevertheless, stimulating neuroregeneration remains ambitious. Even though important discoveries have been made over the past decades, they did not translate into a therapy yet. Actually, this is not surprising; while these disorders mainly manifest in aged individuals, most of the research is being performed in young animal models. Aging of neurons and their environment, however, greatly affects the central nervous system and its capacity to repair. This review provides a detailed overview of the impact of aging on central nervous system functioning and regeneration potential, both in non-regenerating and spontaneously regenerating animal models. Additionally, we highlight the need for aging animal models with regenerative capacities in the search for neuroreparative strategies.
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Affiliation(s)
- Sophie Vanhunsel
- Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium
| | - An Beckers
- Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium
| | - Lieve Moons
- Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium.
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26
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Woollacott IOC, Toomey CE, Strand C, Courtney R, Benson BC, Rohrer JD, Lashley T. Microglial burden, activation and dystrophy patterns in frontotemporal lobar degeneration. J Neuroinflammation 2020; 17:234. [PMID: 32778130 PMCID: PMC7418403 DOI: 10.1186/s12974-020-01907-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 07/21/2020] [Indexed: 12/14/2022] Open
Abstract
Background Microglial dysfunction is implicated in frontotemporal lobar degeneration (FTLD). Although studies have reported excessive microglial activation or senescence (dystrophy) in Alzheimer’s disease (AD), few have explored this in FTLD. We examined regional patterns of microglial burden, activation and dystrophy in sporadic and genetic FTLD, sporadic AD and controls. Methods Immunohistochemistry was performed in frontal and temporal grey and white matter from 50 pathologically confirmed FTLD cases (31 sporadic, 19 genetic: 20 FTLD-tau, 26 FTLD-TDP, four FTLD-FUS), five AD cases and five controls, using markers to detect phagocytic (CD68-positive) and antigen-presenting (CR3/43-positive) microglia, and microglia in general (Iba1-positive). Microglial burden and activation (morphology) were assessed quantitatively for each microglial phenotype. Iba1-positive microglia were assessed semi-quantitatively for dystrophy severity and qualitatively for rod-shaped and hypertrophic morphology. Microglia were compared in each region between FTLD, AD and controls, and between different pathological subtypes of FTLD, including its main subtypes (FTLD-tau, FTLD-TDP, FTLD-FUS), and subtypes of FTLD-tau, FTLD-TDP and genetic FTLD. Microglia were also compared between grey and white matter within each lobe for each group. Results There was a higher burden of phagocytic and antigen-presenting microglia in FTLD and AD cases than controls, but activation was often not increased. Burden was generally higher in white matter than grey matter, but activation was greater in grey matter. However, microglia varied regionally according to FTLD subtype and disease mechanism. Dystrophy was more severe in FTLD and AD than controls, and more severe in white than grey matter, but this also varied regionally and was particularly extensive in FTLD due to progranulin (GRN) mutations. Presence of rod-shaped and hypertrophic microglia also varied by FTLD subtype. Conclusions This study demonstrates regionally variable microglial involvement in FTLD and links this to underlying disease mechanisms. This supports investigation of microglial dysfunction in disease models and consideration of anti-senescence therapies in clinical trials.
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Affiliation(s)
- Ione O C Woollacott
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Christina E Toomey
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ, UK.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Catherine Strand
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ, UK
| | - Robert Courtney
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ, UK
| | - Bridget C Benson
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ, UK.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Jonathan D Rohrer
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Tammaryn Lashley
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ, UK. .,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.
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27
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Cao D, Li XH, Luo XG, Yu HM, Wan LS, Wei L, Ren Y. Phorbol myristate acetate induces cellular senescence in rat microglia in vitro. Int J Mol Med 2020; 46:415-426. [PMID: 32626908 DOI: 10.3892/ijmm.2020.4587] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 03/19/2020] [Indexed: 11/05/2022] Open
Abstract
The present study aimed to establish a cellular model to test the hypothesis that oncogene-induced senescence (OIS) is triggered by aging-related activation of microglia. Primary microglia were incubated with phorbol 12-myristate 13-acetate (PMA), and β-galactosidase (β-Gal) staining was applied to subsequent assessment of cellular senescence. Moreover, flow cytometry was employed for examinations of cell cycle arrest and senescence-associated proteins, p53 and p21 were measured by western blotting. Furthermore, examination of tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) were carried out with microglia supernatants undergoing age-related degenerative diseases in the nervous system, using ELISA. PC12 cells were co-cultured with microglia activated by aging-related alteration(s) to evaluate whether apoptosis was increased in PC12 cells. Cellular senescence-associated β-Gal staining showed that microglial β-Gal expression gradually increased with prolonged PMA stimulation. Microglia in the group receiving 72 h of PMA stimulation displayed the highest percentage of cells arrested in G0/G1, the highest amount of senescence-associated expression of p53 and p21, and the most prominent secretion of TNF-α and IL-1β. In comparison with controls, an increase of apoptotic PC12 cells was detected, which were co-cultured with aging microglia. Taken together, microglia tend to undergo senescence after PMA treatment, suggesting that microglial senescence is associated with inactivation of certain oncogenes.
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Affiliation(s)
- Dan Cao
- Department of Geriatrics, The Fourth People's Hospital of Shenyang, Shenyang, Liaoning 110031, P.R. China
| | - Xiao-Hong Li
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xiao-Guang Luo
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Hong-Mei Yu
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Li-Shu Wan
- Department of Neurology, The First Hospital of Dandong, Dandong, Liaoning 118000, P.R. China
| | - Ling Wei
- Department of Geriatrics, The Fourth People's Hospital of Shenyang, Shenyang, Liaoning 110031, P.R. China
| | - Yan Ren
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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28
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Streit WJ, Khoshbouei H, Bechmann I. Dystrophic microglia in late-onset Alzheimer's disease. Glia 2020; 68:845-854. [PMID: 31922322 DOI: 10.1002/glia.23782] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 12/23/2019] [Accepted: 12/30/2019] [Indexed: 01/08/2023]
Abstract
Here, we summarize current understanding of functional involvement of microglial cells in the most common neurodegenerative disease to affect humans, which is sporadic or late-onset Alzheimer's disease (LOAD). Our review narrowly focuses on insights obtained from post-mortem neuropathological examinations of human brains paying particular attention to microglia as these cells have long been implicated as pivotal players in the cellular processes that lead to AD-type neurodegeneration. Although complete understanding of the roles played by microglia in AD neurodegeneration remains elusive, our studies thus far have illuminated microglial involvement in LOAD, showing that microglial dystrophy, the morphological manifestation of senescence, can be integrated with other hallmark pathological features of AD, such as intraneuronal neurofibrillary degeneration (NFD) and extracellular deposits of amyloid-beta (Aβ) protein. We have demonstrated an in situ correlation between microglial dystrophy and presence of NFD suggesting that neurodegeneration is secondary to aging-related microglial deterioration, a concept founded on the notion that proper neuronal function is dependent on presence of healthy microglia. Diseased or weakened glia are detrimental for neuronal well-being because their ability to provide neuronal support may be impaired. Our most recent work also links microglial dystrophy with Aβ deposits by showing that there is a chronic, yet futile microglial reaction to insoluble amyloid deposits. This inability of microglia to remove aggregated amyloid (a foreign body) causes microglial exhaustion and thereby exacerbates already ongoing aging-dependent microglial deterioration. An eventual total loss of functional microglia in advanced LOAD promotes widespread NFD, dementia, and brain failure.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida
| | - Ingo Bechmann
- Anatomical Institute, University of Leipzig, Leipzig, Germany
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29
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Angelova DM, Brown DR. Microglia and the aging brain: are senescent microglia the key to neurodegeneration? J Neurochem 2019; 151:676-688. [PMID: 31478208 DOI: 10.1111/jnc.14860] [Citation(s) in RCA: 152] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/21/2019] [Accepted: 08/23/2019] [Indexed: 12/15/2022]
Abstract
The single largest risk factor for etiology of neurodegenerative diseases like Alzheimer's disease is increased age. Therefore, understanding the changes that occur as a result of aging is central to any possible prevention or cure for such conditions. Microglia, the resident brain glial population most associated with both protection of neurons in health and their destruction is disease, could be a significant player in age related changes. Microglia can adopt an aberrant phenotype sometimes referred to either as dystrophic or senescent. While aged microglia have been frequently identified in neurodegenerative diseases such as Alzheimer's disease, there is no conclusive evidence that proves a causal role. This has been hampered by a lack of models of aged microglia. We have recently generated a model of senescent microglia based on the observation that all dystrophic microglia show iron overload. Iron-overloading cultured microglia causes them to take on a senescent phenotype and can cause changes in models of neurodegeneration similar to those observed in patients. This review considers how this model could be used to determine the role of senescent microglia in neurodegenerative diseases.
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Affiliation(s)
- Dafina M Angelova
- Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - David R Brown
- Department of Biology and Biochemistry, University of Bath, Bath, UK
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30
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Faissner S, Plemel JR, Gold R, Yong VW. Progressive multiple sclerosis: from pathophysiology to therapeutic strategies. Nat Rev Drug Discov 2019; 18:905-922. [PMID: 31399729 DOI: 10.1038/s41573-019-0035-2] [Citation(s) in RCA: 262] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2019] [Indexed: 02/07/2023]
Abstract
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that involves demyelination and axonal degeneration. Although substantial progress has been made in drug development for relapsing-remitting MS, treatment of the progressive forms of the disease, which are characterized clinically by the accumulation of disability in the absence of relapses, remains unsatisfactory. This unmet clinical need is related to the complexity of the pathophysiological mechanisms involved in MS progression. Chronic inflammation, which occurs behind a closed blood-brain barrier with activation of microglia and continued involvement of T cells and B cells, is a hallmark pathophysiological feature. Inflammation can enhance mitochondrial damage in neurons, which, consequently, develop an energy deficit, further reducing axonal health. The growth-inhibitory and inflammatory environment of lesions also impairs remyelination, a repair process that might protect axons from degeneration. Moreover, neurodegeneration is accelerated by the altered expression of ion channels on denuded axons. In this Review, we discuss the current understanding of these disease mechanisms and highlight emerging therapeutic strategies based on these insights, including those targeting the neuroinflammatory and degenerative aspects as well as remyelination-promoting approaches.
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Affiliation(s)
- Simon Faissner
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany. .,Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
| | - Jason R Plemel
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Ralf Gold
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
| | - V Wee Yong
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
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31
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Ritzel RM, Doran SJ, Glaser EP, Meadows VE, Faden AI, Stoica BA, Loane DJ. Old age increases microglial senescence, exacerbates secondary neuroinflammation, and worsens neurological outcomes after acute traumatic brain injury in mice. Neurobiol Aging 2019; 77:194-206. [PMID: 30904769 PMCID: PMC6486858 DOI: 10.1016/j.neurobiolaging.2019.02.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/31/2019] [Accepted: 02/09/2019] [Indexed: 01/10/2023]
Abstract
After traumatic brain injury (TBI), individuals aged over 65 years show increased mortality and worse functional outcomes compared with younger persons. As neuroinflammation is a key pathobiological mechanism of secondary injury after TBI, we examined how aging affects post-traumatic microglial responses and functional outcomes. Young (3-month-old) and aged (18-month-old) male C57Bl/6 mice were subjected to moderate-level controlled cortical impact or sham surgery, and neurological function was evaluated. At 72 hours after injury, brain, blood, and spleen leukocyte counts were assessed ex vivo using flow cytometry. Aged mice demonstrated more severe deficits in forelimb grip strength, balance and motor coordination, spontaneous locomotor activity, and anxiety-like behavior. These animals also exhibited more robust microglial proliferation and significantly higher numbers of brain-infiltrating leukocytes. Microglia in aged mice showed impairments in phagocytic activity and higher production of interleukin-1β (IL-1β). Infiltrating myeloid cells in aged TBI mice also had deficits in phagocytosis but showed diminished proinflammatory cytokine production and greater reactive oxygen species production. Expression of several senescence markers (Bcl-2, p16ink4a, p21cip1a, lipofuscin, and H2AX [pS139]) was increased with age and/or TBI in both microglia and injured cortex. Although there was no difference in the number of circulating blood neutrophils as a function of age, young mice exhibited more pronounced TBI-induced splenomegaly and splenic myeloid cell expansion. Thus, worse post-traumatic behavioral outcomes in aged animals are associated with exaggerated microglial responses, increased leukocyte invasion, and upregulation of senescence markers.
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Affiliation(s)
- Rodney M Ritzel
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sarah J Doran
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ethan P Glaser
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Victoria E Meadows
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA.
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32
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Kelly ÁM. Exercise-Induced Modulation of Neuroinflammation in Models of Alzheimer's Disease. Brain Plast 2018; 4:81-94. [PMID: 30564548 PMCID: PMC6296260 DOI: 10.3233/bpl-180074] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2018] [Indexed: 12/17/2022] Open
Abstract
Alzheimer's disease (AD), a progressive, neurodegenerative condition characterised by accumulation of toxic βeta-amyloid (Aβ) plaques, is one of the leading causes of dementia globally. The cognitive impairment that is a hallmark of AD may be caused by inflammation in the brain triggered and maintained by the presence of Aβ protein, ultimately leading to neuronal dysfunction and loss. Since there is a significant inflammatory component to AD, it is postulated that anti-inflammatory strategies may be of prophylactic or therapeutic benefit in AD. One such strategy is that of regular physical activity, which has been shown in epidemiological studies to be protective against various forms of dementia including AD. Exercise induces an anti-inflammatory environment in peripheral organs and also increases expression of anti-inflammatory molecules within the brain. Here we review the evidence, mainly from animal models of AD, supporting the hypothesis that exercise can reduce or slow the cellular and cognitive impairments associated with AD by modulating neuroinflammation.
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Affiliation(s)
- Áine M. Kelly
- Department of Physiology, School of Medicine & Trinity College Institute of Neuroscience & Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
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33
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Martínez Cerdeño V, Hong T, Amina S, Lechpammer M, Ariza J, Tassone F, Noctor SC, Hagerman P, Hagerman R. Microglial cell activation and senescence are characteristic of the pathology FXTAS. Mov Disord 2018; 33:1887-1894. [PMID: 30537011 DOI: 10.1002/mds.27553] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/15/2018] [Accepted: 09/27/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder associated with premutation alleles of the FMR1 gene. Expansions of more than 200 CGG repeats give rise to fragile X syndrome, the most common inherited form of cognitive impairment. Fragile X-associated tremor/ataxia syndrome is characterized by cerebellar tremor and ataxia, and the presence of ubiquitin-positive inclusions in neurons and astrocytes. It has been previously suggested that fragile X-associated tremor/ataxia syndrome is associated with an inflammatory state based on signs of oxidative stress-mediated damage and iron deposition. OBJECTIVE Determine whether the pathology of fragile X-associated tremor/ataxia syndrome involves microglial activation and an inflammatory state. METHODS Using ionized calcium binding adaptor molecule 1 and cluster differentiation 68 antibodies to label microglia, we examined the number and state of activation of microglial cells in the putamen of 13 fragile X-associated tremor/ataxia syndrome and 9 control postmortem cases. RESULTS Nearly half of fragile X-associated tremor/ataxia syndrome cases (6 of 13) presented with dystrophic senescent microglial cells. In the remaining fragile X-associated tremor/ataxia syndrome cases (7 of 13), the number of microglial cells and their activation state were increased compared to controls. CONCLUSIONS The presence of senescent microglial cells in half of fragile X-associated tremor/ataxia syndrome cases suggests that this indicator could be used, together with the presence of intranuclear inclusions and the presence of iron deposits, as a biomarker to aid in the postmortem diagnosis of fragile X-associated tremor/ataxia syndrome. An increased number and activation indicate that microglial cells play a role in the inflammatory state present in the fragile X-associated tremor/ataxia syndrome brain. Anti-inflammatory treatment of patients with fragile X-associated tremor/ataxia syndrome may be indicated to slow neurodegeneration. © 2018 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Verónica Martínez Cerdeño
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, California, USA.,Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children of Northern California, Sacramento, California, USA.,MIND Institute, UC Davis Medical Center, Sacramento, California, USA
| | - Tiffany Hong
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, California, USA.,Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children of Northern California, Sacramento, California, USA
| | - Sarwat Amina
- Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children of Northern California, Sacramento, California, USA.,MIND Institute, UC Davis Medical Center, Sacramento, California, USA
| | - Mirna Lechpammer
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, California, USA
| | - Jeanelle Ariza
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, California, USA.,Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children of Northern California, Sacramento, California, USA
| | - Flora Tassone
- MIND Institute, UC Davis Medical Center, Sacramento, California, USA.,Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine Sacramento, California, USA
| | - Stephen C Noctor
- MIND Institute, UC Davis Medical Center, Sacramento, California, USA.,Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine Sacramento, California, USA
| | - Paul Hagerman
- MIND Institute, UC Davis Medical Center, Sacramento, California, USA.,Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine Sacramento, California, USA
| | - Randi Hagerman
- MIND Institute, UC Davis Medical Center, Sacramento, California, USA.,Department of Pediatrics, UC Davis School of Medicine Sacramento, California, USA
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34
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Spampinato SF, Copani A, Nicoletti F, Sortino MA, Caraci F. Metabotropic Glutamate Receptors in Glial Cells: A New Potential Target for Neuroprotection? Front Mol Neurosci 2018; 11:414. [PMID: 30483053 PMCID: PMC6243036 DOI: 10.3389/fnmol.2018.00414] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 10/25/2018] [Indexed: 12/14/2022] Open
Abstract
Neurodegenerative disorders are characterized by excitotoxicity and neuroinflammation that finally lead to slow neuronal degeneration and death. Although neurons are the principal target, glial cells are important players as they contribute by either exacerbating or dampening the events that lead to neuroinflammation and neuronal damage. A dysfunction of the glutamatergic system is a common event in the pathophysiology of these diseases. Metabotropic glutamate (mGlu) receptors belong to a large family of G protein-coupled receptors largely expressed in neurons as well as in glial cells. They often appear overexpressed in areas involved in neurodegeneration, where they can modulate glutamatergic transmission. Of note, mGlu receptor upregulation may involve microglia or, even more frequently, astrocytes, where their activation causes release of factors potentially able to influence neuronal death. The expression of mGlu receptors has been also reported on oligodendrocytes, a glial cell type specifically involved in the development of multiple sclerosis. Here we will provide a general overview on the possible involvement of mGlu receptors expressed on glial cells in the pathogenesis of different neurodegenerative disorders and the potential use of subtype-selective mGlu receptor ligands as candidate drugs for the treatment of neurodegenerative disorders. Negative allosteric modulators (NAM) of mGlu5 receptors might represent a relevant pharmacological tool to develop new neuroprotective strategies in these diseases. Recent evidence suggests that targeting astrocytes and microglia with positive allosteric modulators (PAM) of mGlu3 receptor or oligodendrocytes with mGlu4 PAMS might represent novel pharmacological approaches for the treatment of neurodegenerative disorders.
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Affiliation(s)
| | - Agata Copani
- Department of Drug Sciences, University of Catania, Catania, Italy.,Institute of Biostructure and Bioimaging, National Research Council, Catania, Italy
| | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Neuromed, Istituto di Ricovero e Cura a Carattere Scientifico, Pozzilli, Italy
| | - Maria Angela Sortino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Caraci
- Department of Drug Sciences, University of Catania, Catania, Italy.,Oasi Research Institute, Istituto di Ricovero e Cura a Carattere Scientifico, Troina, Italy
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Novak P, Kontsekova E, Zilka N, Novak M. Ten Years of Tau-Targeted Immunotherapy: The Path Walked and the Roads Ahead. Front Neurosci 2018; 12:798. [PMID: 30450030 PMCID: PMC6224648 DOI: 10.3389/fnins.2018.00798] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/15/2018] [Indexed: 12/14/2022] Open
Abstract
Neurofibrillary pathology comprised of pathological tau protein is closely tied to a range of neurodegenerative disorders, the most common of which is Alzheimer's disease. While they are individually rarer, a range of other disorders, the tauopathies (including Pick's disease, progressive supranuclear palsy, corticobasal degeneration, primary progressive aphasia, and ∼50% of behavioral variant frontotemporal dementia cases) display pronounced underlying tau pathology. In all cases, the distribution and amount of tau pathology closely correlates with the severity and phenotype of cognitive impairment, and with the pattern and degree of brain atrophy. Successfully counteracting tau pathology is likely to halt or slow the progression of these debilitating disorders. This makes tau a target of prime importance, yet an elusive one. The diversity of the tau proteome and post-translational modifications, as well as pathophysiology of tau are reviewed. Beginning 2013, a range of tau-targeted immunotherapies have entered clinical development; these therapies, and their common themes and differences are reviewed. The manuscript provides an extensive discussion on epitope selection for immunotherapies against tau pathology, on immunological mechanisms involved in their action, and challenges such as immune senescence, vaccine design, or evolution of epitopes. Furthermore, we provide methodological recommendations for the characterization of active vaccines and antibodies, animal models, and the target itself - the diseased tau proteome.
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Affiliation(s)
- Petr Novak
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
- AXON Neuroscience CRM Services SE, Bratislava, Slovakia
| | - Eva Kontsekova
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
- AXON Neuroscience R&D Services SE, Bratislava, Slovakia
| | - Norbert Zilka
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
- AXON Neuroscience R&D Services SE, Bratislava, Slovakia
| | - Michal Novak
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
- AXON Neuroscience SE, Larnaca, Cyprus
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36
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Mishra A, Brinton RD. Inflammation: Bridging Age, Menopause and APOEε4 Genotype to Alzheimer's Disease. Front Aging Neurosci 2018; 10:312. [PMID: 30356809 PMCID: PMC6189518 DOI: 10.3389/fnagi.2018.00312] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/18/2018] [Indexed: 12/19/2022] Open
Abstract
Neuro-inflammatory processes that contribute to development of Alzheimer’s are evident early in the latent prodromal phase and worsen during the course of the disease. Despite substantial mechanistic and clinical evidence of inflammation, therapeutic approaches targeting inflammation have failed to alter the course of the disease. Disparate results from epidemiological and clinical trials targeting inflammation, highlight the complexity of the inflammatory process. Herein we review the dynamics of the inflammatory process across aging, midlife endocrine transitions, and the APOEε4 genotype and their contribution to progression of Alzheimer’s disease (AD). We discuss the chronic inflammatory processes that are activated during midlife chronological and endocrine aging, which ultimately limit the clearance capacity of microglia and lead to immune senescence. Aging, menopause, and APOEε4 combine the three hits of a compromised bioenergetic system of menopause with the chronic low grade innate inflammation of aging with the APOEε4 dyslipidemia and adaptive immune response. The inflammatory immune response is the unifying factor that bridges across each of the risk factors for AD. Immune system regulators that are specific to stage of disease and inflammatory phenotype would provide a therapeutic strategy to disconnect the bridge that drives disease. Outcomes of this analysis provide plausible mechanisms underlying failed clinical trials of anti-inflammatory agents in Alzheimer’s patients. Further, they highlight the need for stratifying AD clinical trial cohorts based on inflammatory phenotype. Combination therapies that include targeted use of anti-inflammatory agent’s specific to the immune phenotype are considered.
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Affiliation(s)
- Aarti Mishra
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA, United States.,Center for Innovation in Brain Science, University of Arizona, Tucson, AZ, United States
| | - Roberta D Brinton
- Center for Innovation in Brain Science, University of Arizona, Tucson, AZ, United States.,Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States.,Department of Neurology, College of Medicine, University of Arizona, Tucson, AZ, United States
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37
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Santoro A, Spinelli CC, Martucciello S, Nori SL, Capunzo M, Puca AA, Ciaglia E. Innate immunity and cellular senescence: The good and the bad in the developmental and aged brain. J Leukoc Biol 2018; 103:509-524. [PMID: 29389023 DOI: 10.1002/jlb.3mr0118-003r] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 01/12/2018] [Accepted: 01/12/2018] [Indexed: 12/21/2022] Open
Abstract
Ongoing studies evidence cellular senescence in undifferentiated and specialized cells from tissues of all ages. Although it is believed that senescence plays a wider role in several stress responses in the mature age, its participation in certain physiological and pathological processes throughout life is coming to light. The "senescence machinery" has been observed in all brain cell populations, including components of innate immunity (e.g., microglia and astrocytes). As the beneficial versus detrimental implications of senescence is an open question, we aimed to analyze the contribution of immune responses in regulatory mechanisms governing its distinct functions in healthy (development, organogenesis, danger patrolling events) and diseased brain (glioma, neuroinflammation, neurodeneration), and the putative connection between cellular and molecular events governing the 2 states. Particularly this review offers new insights into the complex roles of senescence both as a chronological event as age advances, and as a molecular mechanism of brain homeostasis through the important contribution of innate immune responses and their crosstalk with neighboring cells in brain parenchyma. We also highlight the impact of the recently described glymphatic system and brain lymphatic vasculature in the interplay between peripheral and central immune surveillance and its potential implication during aging. This will open new ways to understand brain development, its deterioration during aging, and the occurrence of several oncological and neurodegenerative diseases.
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Affiliation(s)
- Antonietta Santoro
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Via Salvatore Allende, Baronissi, Italy
| | | | | | - Stefania Lucia Nori
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Via Salvatore Allende, Baronissi, Italy
| | - Mario Capunzo
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Via Salvatore Allende, Baronissi, Italy
| | - Annibale Alessandro Puca
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Via Salvatore Allende, Baronissi, Italy.,Cardiovascular Research Unit, IRCCS MultiMedica, Milan, Italy
| | - Elena Ciaglia
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Via Salvatore Allende, Baronissi, Italy
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38
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Suárez-Calvet M, Araque Caballero MÁ, Kleinberger G, Bateman RJ, Fagan AM, Morris JC, Levin J, Danek A, Ewers M, Haass C. Early changes in CSF sTREM2 in dominantly inherited Alzheimer's disease occur after amyloid deposition and neuronal injury. Sci Transl Med 2017; 8:369ra178. [PMID: 27974666 DOI: 10.1126/scitranslmed.aag1767] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 11/23/2016] [Indexed: 12/30/2022]
Abstract
Emerging evidence supports a role for innate immunity and microglia in Alzheimer's disease (AD) pathophysiology. However, no marker related to microglia has been included in the temporal evolution models of AD. TREM2 is a transmembrane protein involved in innate immunity and is selectively expressed by microglia and genetically linked to AD and other neurodegenerative disorders. Its ectodomain is released by proteolysis as a soluble variant (sTREM2) and can be detected in the cerebrospinal fluid (CSF). In patients with autosomal dominant AD, we tested how many years before the expected symptom onset did CSF sTREM2 increase in mutation carriers (MCs) compared to noncarriers (NCs). We also determined the temporal sequence of changes in CSF sTREM2 and markers for amyloid deposition and neurodegeneration as well as cognitive performance. We included 218 participants consisting of 127 MC and 91 NC siblings from the Dominantly Inherited Alzheimer Network. We observed that CSF sTREM2 increased in MCs compared to NCs 5 years before the expected symptom onset and this difference remained significant until 5 years after the expected symptom onset. Changes in CSF sTREM2 occurred after alterations were observed in markers for brain amyloidosis and neuronal injury. We propose that microglial activation occurs several years before the expected symptom onset, but after amyloidosis and neuronal injury have already occurred.
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Affiliation(s)
- Marc Suárez-Calvet
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.,Biomedical Center, Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Miguel Ángel Araque Caballero
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Gernot Kleinberger
- Biomedical Center, Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Randall J Bateman
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Knight Alzheimer's Disease Research Center, Washington University in St. Louis, St. Louis, MO 63110, USA.,Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Anne M Fagan
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Knight Alzheimer's Disease Research Center, Washington University in St. Louis, St. Louis, MO 63110, USA.,Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - John C Morris
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Knight Alzheimer's Disease Research Center, Washington University in St. Louis, St. Louis, MO 63110, USA.,Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Johannes Levin
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.,Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Adrian Danek
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.,Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Michael Ewers
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.
| | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany. .,Biomedical Center, Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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39
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Changes in neocortical and hippocampal microglial cells during hibernation. Brain Struct Funct 2017; 223:1881-1895. [PMID: 29260372 DOI: 10.1007/s00429-017-1596-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/15/2017] [Indexed: 12/29/2022]
Abstract
Mammalian hibernation proceeds alongside a wide range of complex brain adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. Using immunofluorescence, confocal microscopy, quantitative analysis methods and intracellular injections, we have characterized microglia morphological changes that occur in the neocortex and hippocampus of the Syrian hamster during hibernation. In euthermic hamsters, microglial cells showed the typical ramified/resting morphology with multiple long, thin and highly-branched processes homogeneously immunostained for Iba-1. However, during torpor, microglial cell process numbers increase significantly accompanied by a shortening of the Iba-1 immunoreactive processes, which show a fragmented appearance. Adaptative changes of microglial cells during torpor coursed with no expression of microglial cell activation markers. We discuss the possibility that these morphological changes may contribute to neuronal damage prevention during hibernation.
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40
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Tennakoon A, Katharesan V, Johnson IP. Brainstem cytokine changes in healthy ageing and Motor Neurone Disease. J Neurol Sci 2017; 381:192-199. [PMID: 28991679 DOI: 10.1016/j.jns.2017.08.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 07/12/2017] [Accepted: 08/08/2017] [Indexed: 11/18/2022]
Abstract
Neuroinflammation is linked to healthy ageing, but its role in the development of age-related neurodegenerative diseases is unclear. In this pilot study we used a multiplex assay approach to compare 27 cytokines in 6 young adult and 6 ageing control brainstems with those in 6 MND brainstems. We report that healthy ageing is associated with significantly increased brainstem levels of IL-1β, IP-10 and MIP-1β which co-localise immunocytochemically to astrocytes. MND brainstem is also characterised by a general increase in both pro- and anti-cytokine levels, but fails to show the expected age-related increase in MIP-1β and IP-10. This pilot study is the first to show that MND is associated with a failure of specific features of the normal age-related neuroinflammatory process. We suggest that our pilot data indicates that neuroinflammation during healthy ageing may not always be detrimental to motoneuronal survival and that age-related neurodegenerative diseases, such as MND, may instead result from defective neuroinflammation.
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Affiliation(s)
- Anuradha Tennakoon
- Discipline of Anatomy and Pathology, The University of Adelaide, SA5005, Australia
| | - Viythia Katharesan
- Discipline of Anatomy and Pathology, The University of Adelaide, SA5005, Australia
| | - Ian P Johnson
- Discipline of Anatomy and Pathology, The University of Adelaide, SA5005, Australia.
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41
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Verbeeck C, Carrano A, Chakrabarty P, Jankowsky JL, Das P. Combination of Aβ Suppression and Innate Immune Activation in the Brain Significantly Attenuates Amyloid Plaque Deposition. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:2886-2894. [PMID: 28919107 DOI: 10.1016/j.ajpath.2017.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/01/2017] [Accepted: 08/07/2017] [Indexed: 01/22/2023]
Abstract
Anti-Aβ clinical trials are currently under way to determine whether preventing amyloid deposition will be beneficial in arresting progression of Alzheimer disease. Both clinical and preclinical studies suggest that antiamyloid strategies are only effective if started at early stages of the disease process in a primary prevention strategy. Because this approach will be difficult to deploy, strategies for secondary prevention aimed at later stages of disease are also needed. In this study, we asked whether combining innate immune activation in the brain with concurrent Aβ suppression could enhance plaque clearance and could improve pathologic outcomes in mice with moderate amyloid pathologic disorder. Starting at 5 months of age, tet-off amyloid precursor protein transgenic mice were treated with doxycycline (dox) to suppress further amyloid precursor protein/Aβ production, and at the same time mice were intracranially injected with adeno-associated virus 1 expressing murine IL-6 (AAV1-mIL-6). Three months later, mice treated with the combination of Aβ suppression and AAV1-mIL-6 showed significantly less plaque pathologic disorder than dox or AAV1-mIL-6 only groups. The combination of AAV1-mIL-6 + dox treatment lowered total plaque burden by >60% versus untreated controls. Treatment with either dox or AAV1-mIL-6 alone was less effective than the combination. Our results suggest a synergistic mechanism by which the up-regulation of mIL-6 was able to improve plaque clearance in the setting of Aβ suppression.
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Affiliation(s)
- Christophe Verbeeck
- Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, Florida
| | - Anna Carrano
- Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, Florida
| | - Paramita Chakrabarty
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida
| | | | - Pritam Das
- Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, Florida.
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42
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Abstract
The concept of the immunological privilege of the central nervous system (CNS) has had a profound influence on studies of interactions between the immune system and the CNS. At one time there was considerable debate as to whether there were any cells in the CNS of myeloid origin, but we now know that there are a number of populations of myeloid cells in specialized compartments of the CNS and that there is an ongoing bidirectional dialogue between the CNS and the immune system. We briefly review what we know of the different myeloid populations, in particular the microglia: their phenotype and function; their role in CNS homeostasis; and also their role in pathology, focusing on chronic neurodegeneration.
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43
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Williams PA, Marsh-Armstrong N, Howell GR. Neuroinflammation in glaucoma: A new opportunity. Exp Eye Res 2017; 157:20-27. [PMID: 28242160 PMCID: PMC5497582 DOI: 10.1016/j.exer.2017.02.014] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 02/16/2017] [Accepted: 02/23/2017] [Indexed: 10/20/2022]
Abstract
Mounting evidence suggests neuroinflammation is a key process in glaucoma, yet the precise roles are not known. Understanding these complex processes, which may also be a key in other common neurodegenerations such as Alzheimer's disease, will lead to targeted therapeutics for a disease that affects as many as 80 million people worldwide. Here, we define neuroinflammation as any immune-relevant response by a variety of cell types including astrocytes, microglia, and peripherally derived cells occurring in the optic nerve head and/or retina. In this review article, we first discuss clinical evidence for neuroinflammation in glaucoma and define neuroinflammation in glaucoma. We then review the inflammatory pathways that have been associated with glaucoma. Finally, we set out key research directions that we believe will greatly advance our understanding of the role of neuroinflammation in glaucoma. This review arose from a discussion of neuroinflammation in glaucoma at the 2015 meeting of The Lasker/IRRF Initiative for Innovation in Vision Science. This manuscript sets out to summarize one of these sessions; "Inflammation and Glaucomatous Neurodegeneration", as well as to review the current state of the literature surrounding neuroinflammation in glaucoma.
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Affiliation(s)
| | - Nick Marsh-Armstrong
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Hugo W. Moser Research Institute, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Gareth R Howell
- The Jackson Laboratory, Bar Harbor, ME, USA; Graduate Program of Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, USA.
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44
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Abstract
As the immune-competent cells of the brain, microglia play an increasingly important role in maintaining normal brain function. They invade the brain early in development, transform into a highly ramified phenotype, and constantly screen their environment. Microglia are activated by any type of pathologic event or change in brain homeostasis. This activation process is highly diverse and depends on the context and type of the stressor or pathology. Microglia can strongly influence the pathologic outcome or response to a stressor due to the release of a plethora of substances, including cytokines, chemokines, and growth factors. They are the professional phagocytes of the brain and help orchestrate the immunological response by interacting with infiltrating immune cells. We describe here the diversity of microglia phenotypes and their responses in health, aging, and disease. We also review the current literature about the impact of lifestyle on microglia responses and discuss treatment options that modulate microglial phenotypes.
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Affiliation(s)
- Susanne A Wolf
- Cellular Neurosciences, Max Delbrück Centre for Molecular Medicine in the Helmholtz Association, Berlin 13092, Germany;
| | - H W G M Boddeke
- Department of Neuroscience, University of Groningen, University Medical Center Groningen, Groningen 9713, The Netherlands
| | - Helmut Kettenmann
- Cellular Neurosciences, Max Delbrück Centre for Molecular Medicine in the Helmholtz Association, Berlin 13092, Germany;
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45
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Bourgade K, Dupuis G, Frost EH, Fülöp T. Anti-Viral Properties of Amyloid-β Peptides. J Alzheimers Dis 2016; 54:859-878. [DOI: 10.3233/jad-160517] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Karine Bourgade
- Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Gilles Dupuis
- Department of Biochemistry, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Eric H. Frost
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Tamàs Fülöp
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
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46
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Echeverria V, Yarkov A, Aliev G. Positive modulators of the α7 nicotinic receptor against neuroinflammation and cognitive impairment in Alzheimer's disease. Prog Neurobiol 2016; 144:142-57. [DOI: 10.1016/j.pneurobio.2016.01.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 11/07/2015] [Accepted: 01/06/2016] [Indexed: 01/08/2023]
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47
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Abstract
Inflammatory activation of microglia is a hallmark of several disorders of the central nervous system. In addition to protecting the brain against inflammatory insults, microglia are neuroprotective and play a significant role in maintaining neuronal connectivity, but the prolongation of an inflammatory status may limit the beneficial functions of these immune cells. The finding that estrogen receptors are present in monocyte-derived cells and that estrogens prevent and control the inflammatory response raise the question of the role that this sex steroid plays in the manifestation and progression of pathologies that have a clear sex difference in prevalence, such as multiple sclerosis, Parkinson's disease, and Alzheimer's disease. The present review aims to provide a critical review of the current literature on the actions of estrogen in microglia and on the involvement of estrogen receptors in the manifestation of selected neurological disorders. This current understanding highlights a research area that should be expanded to identify appropriate replacement therapies to slow the progression of such diseases.
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Affiliation(s)
- Alessandro Villa
- Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Elisabetta Vegeto
- Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Angelo Poletti
- Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Adriana Maggi
- Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
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48
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Age-Related Changes in D-Aspartate Oxidase Promoter Methylation Control Extracellular D-Aspartate Levels and Prevent Precocious Cell Death during Brain Aging. J Neurosci 2016; 36:3064-78. [PMID: 26961959 DOI: 10.1523/jneurosci.3881-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endogenous NMDA receptor (NMDAR) agonist D-aspartate occurs transiently in the mammalian brain because it is abundant during embryonic and perinatal phases before drastically decreasing during adulthood. It is well established that postnatal reduction of cerebral D-aspartate levels is due to the concomitant onset of D-aspartate oxidase (DDO) activity, a flavoenzyme that selectively degrades bicarboxylic D-amino acids. In the present work, we show that d-aspartate content in the mouse brain drastically decreases after birth, whereas Ddo mRNA levels concomitantly increase. Interestingly, postnatal Ddo gene expression is paralleled by progressive demethylation within its putative promoter region. Consistent with an epigenetic control on Ddo expression, treatment with the DNA-demethylating agent, azacitidine, causes increased mRNA levels in embryonic cortical neurons. To indirectly evaluate the effect of a putative persistent Ddo gene hypermethylation in the brain, we used Ddo knock-out mice (Ddo(-/-)), which show constitutively suppressed Ddo expression. In these mice, we found for the first time substantially increased extracellular content of d-aspartate in the brain. In line with detrimental effects produced by NMDAR overstimulation, persistent elevation of D-aspartate levels in Ddo(-/-) brains is associated with appearance of dystrophic microglia, precocious caspase-3 activation, and cell death in cortical pyramidal neurons and dopaminergic neurons of the substantia nigra pars compacta. This evidence, along with the early accumulation of lipufuscin granules in Ddo(-/-) brains, highlights an unexpected importance of Ddo demethylation in preventing neurodegenerative processes produced by nonphysiological extracellular levels of free D-aspartate.
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49
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Bourgade K, Le Page A, Bocti C, Witkowski JM, Dupuis G, Frost EH, Fülöp T. Protective Effect of Amyloid-β Peptides Against Herpes Simplex Virus-1 Infection in a Neuronal Cell Culture Model. J Alzheimers Dis 2016; 50:1227-41. [DOI: 10.3233/jad-150652] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Karine Bourgade
- Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Aurélie Le Page
- Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Christian Bocti
- Department of Medicine, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | | | - Gilles Dupuis
- Department of Biochemistry, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Eric H. Frost
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Tamás Fülöp
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
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50
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Nikodemova M, Small AL, Kimyon RS, Watters JJ. Age-dependent differences in microglial responses to systemic inflammation are evident as early as middle age. Physiol Genomics 2016; 48:336-44. [PMID: 26884461 DOI: 10.1152/physiolgenomics.00129.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 02/10/2016] [Indexed: 01/17/2023] Open
Abstract
Whereas age increases microglial inflammatory activities and impairs their ability to effectively regulate their immune response, it is unclear at what age these exaggerated responses begin. We tested the hypotheses that augmented microglial responses to inflammatory challenge are present as early as middle age and that repeated stimulation of primed microglia in vivo would reveal microglial senescence. Microglial gene expression was investigated in a mouse model of repeated systemic inflammation induced by intraperitoneal injection of bacterial lipopolysaccharide (LPS). Following LPS, microglia from middle-aged mice (9-10 mo) displayed larger increases in Tnfα, Il-6, and Il-1β gene expression compared with young adults (2 mo). Similar results were observed in the spleens of middle-aged mice, indicating that exaggeration of both central and peripheral immune responses are already evident at early middle age. Interestingly, despite greater proinflammatory responses to the first LPS challenge in the aged mice, there were no age-dependent differences in either microglia or spleen following a subsequent LPS dose, suggesting that animals at this age retain the ability to effectively control their immune response following repeated challenge. The exacerbated microglial immune response to systemic inflammation at early middle age suggests that the CNS may be vulnerable to age-dependent alterations earlier than previously appreciated.
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Affiliation(s)
- Maria Nikodemova
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Alissa L Small
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Rebecca S Kimyon
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Jyoti J Watters
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
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