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Pocock J, Vasilopoulou F, Svensson E, Cosker K. Microglia and TREM2. Neuropharmacology 2024:110020. [PMID: 38821351 DOI: 10.1016/j.neuropharm.2024.110020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/20/2024] [Accepted: 05/28/2024] [Indexed: 06/02/2024]
Abstract
TREM2 is a membrane receptor solely expressed on microglia in normal brain. In this review we outline recent advances in TREM2 biology and its implications for microglial function, with particular emphasis on findings from iPSC-derived microglia (iMG) expressing TREM2 loss-of-function mutations. Alterations in receptor proximal and distal signalling underlie TREM2 risk variants linked to neurodegenerative disease, principally NH-linked FTD, and late-onset AD, but emerging data suggest roles for TREM2 in PD, MS and ALS. TREM2 downstream functions include phagocytosis of myelin debris, amyloid beta peptides, and phosphatidylserine-expressing cells (resulting from damage or stress). Microglial survival, migration, DAMP signalling, inflammasome activation, and intercellular signalling including tau spreading via exosomes, as well as roles for sTREM2 ain protection and as a biomarker are discussed. The role of TREM2 in metabolic homeostasis, and immunometabolic switching are discussed regarding microglial responses to damage and protection. The use of iPSC models to investigate the role of TREM2 in AD, PD, MS, ALS, and other neurodegenerative diseases could prove invaluable due to their ability to recapitulate human pathology, allowing a full understanding of TREM2 and microglial involvement in the underlying disease mechanisms and progression.
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Affiliation(s)
- Jennifer Pocock
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK.
| | - Foteini Vasilopoulou
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Elina Svensson
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Katharina Cosker
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK
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Cai Y, Shi D, Lan G, Chen L, Jiang Y, Zhou L, Guo T. Association of β-Amyloid, Microglial Activation, Cortical Thickness, and Metabolism in Older Adults Without Dementia. Neurology 2024; 102:e209205. [PMID: 38489560 DOI: 10.1212/wnl.0000000000209205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/13/2023] [Indexed: 03/17/2024] Open
Abstract
BACKGROUND AND OBJECTIVES Plasma β-amyloid42 (Aβ42)/Aβ40 levels have shown promise in identifying Aβ-PET positive individuals. This study explored the concordance and discordance of plasma Aβ42/Aβ40 positivity (Plasma±) with CSF Aβ42/Aβ40 positivity (CSF±) and Aβ-PET positivity (PET±) in older adults without dementia. Associations of Aβ deposition, cortical thickness, glucose metabolism, and microglial activation were also investigated. METHODS We selected participants without dementia who had concurrent plasma Aβ42/Aβ40 and Aβ-PET scans from the Alzheimer's Disease Neuroimaging Initiative cohort. Participants were categorized into Plasma±/PET± based on thresholds of composite 18F-florbetapir (FBP) standardized uptake value ratio (SUVR) ≥1.11 and plasma Aβ42/Aβ40 ≤0.1218. Aβ-PET-negative individuals were further divided into Plasma±/CSF± (CSF Aβ42/Aβ40 ≤0.138), and the concordance and discordance of Aβ42/Aβ40 in the plasma and CSF were investigated. Baseline and slopes of regional FBP SUVR were compared among Plasma±/PET± groups, and associations of regional FBP SUVR, FDG SUVR, cortical thickness, and CSF soluble Triggering Receptor Expressed on Myeloid Cell 2 (sTREM2) levels were analyzed. RESULTS One hundred eighty participants (mean age 72.7 years, 51.4% female, 96 cognitively unimpaired, and 84 with mild cognitive impairment) were included. We found that the proportion of Plasma+/PET- individuals was 6.14 times higher (odds ratio (OR) = 6.143, 95% confidence interval (CI) 2.740-16.185, p < 0.001) than that of Plasma-/PET+ individuals, and Plasma+/CSF- individuals showed 8.5 times larger percentage (OR = 8.5, 95% CI: 3.031-32.974, p < 0.001) than Plasma-/CSF+ individuals in Aβ-PET-negative individuals. Besides, Plasma+/PET- individuals exhibited faster (p < 0.05) Aβ accumulation predominantly in bilateral banks of superior temporal sulcus (BANKSSTS) and supramarginal, and superior parietal cortices compared with Plasma-/PET- individuals, despite no difference in baseline FBP SUVRs. In Plasma+/PET+ individuals, higher CSF sTREM2 levels correlated with slower BANKSSTS Aβ accumulation (standardized β (βstd) = -0.418, 95% CI -0.681 to -0.154, p = 0.002). Conversely, thicker cortical thickness and higher glucose metabolism in supramarginal and superior parietal cortices were associated with faster (p < 0.05) CSF sTREM2 increase in Plasma+/PET- individuals rather than in Plasma+/PET+ individuals. DISCUSSION These findings suggest that plasma Aβ42/Aβ40 abnormalities may predate CSF Aβ42/Aβ40 and Aβ-PET abnormalities. Higher sTREM2-related microglial activation is linked to thicker cortical thickness and higher metabolism in early amyloidosis stages but tends to mitigate Aβ accumulation primarily at relatively advanced stages.
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Affiliation(s)
- Yue Cai
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
| | - Dai Shi
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
| | - Guoyu Lan
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
| | - Linting Chen
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
| | - Yanni Jiang
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
| | - Liemin Zhou
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
| | - Tengfei Guo
- From the Institute of Biomedical Engineering (Y.C., G.L., L.C., T.G.), Shenzhen Bay Laboratory; Neurology Medicine Center (D.S., L.Z.), The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China; Department of Psychology (Y.J.), University of Texas at Austin; and Institute of Biomedical Engineering (T.G.), Peking University Shenzhen Graduate School, China
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Feng S, Wu Z, Zheng X, Shao Z, Lin Q, Sun S. Abnormal levels of expression of microRNAs in peripheral blood of patients with traumatic brain injury are induced by microglial activation and correlated with severity of injury. Eur J Med Res 2024; 29:188. [PMID: 38504296 PMCID: PMC10953077 DOI: 10.1186/s40001-024-01790-y] [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: 02/17/2024] [Accepted: 03/12/2024] [Indexed: 03/21/2024] Open
Abstract
BACKGROUND Microglia play a crucial role in regulating the progression of traumatic brain injury (TBI). In specific, microglia can self-activate and secrete various substances that exacerbate or alleviate the neuroimmune response to TBI. In addition, microRNAs (miRNAs) are involved in the functional regulation of microglia. However, molecular markers that reflect the dynamics of TBI have not yet been found in peripheral tissues. METHODS Paired samples of peripheral blood were collected from patients with TBI before and after treatment. Next-generation sequencing and bioinformatics analysis were used to identify the main pathways and biological functions of TBI-related miRNAs in the samples. Moreover, lipopolysaccharide-treated human microglia were used to construct a cellular immune-activation model. This was combined with analysis of peripheral blood samples to screen for highly expressed miRNAs derived from activated microglia after TBI treatment. Quantitative reverse-transcriptase polymerase chain reaction was used to determine the expression levels of these miRNAs, allowing their relationship with the severity of TBI to be examined. Receiver operating characteristic (ROC) curves were constructed to analyse the clinical utility of these miRNAs for determining the extent of TBI. RESULTS Sequencing results showed that 37 miRNAs were differentially expressed in peripheral blood samples from patients with TBI before and after treatment, with 17 miRNAs being upregulated and 20 miRNAs being downregulated after treatment. The expression profiles of these miRNAs were verified in microglial inflammation models and in the abovementioned peripheral blood samples. The results showed that hsa-miR-122-5p and hsa-miR-193b-3p were highly expressed in the peripheral blood of patients with TBI after treatment and that the expression levels of these miRNAs were correlated with the patients' scores on the Glasgow Coma Scale. ROC curve analysis revealed that abnormally high levels of expression of hsa-miR-122-5p and hsa-miR-193b-3p in peripheral blood have some clinical utility for distinguishing different extents of TBI and thus could serve as biomarkers of TBI. CONCLUSION Abnormally high levels of expression of hsa-miR-122-5p and hsa-miR-193b-3p in the peripheral blood of patients with TBI were due to the activation of microglia and correlated with the severity of TBI. This discovery may help to increase understanding of the molecular pathology of TBI and guide the development of new strategies for TBI therapy based on microglial function.
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Affiliation(s)
- Shuo Feng
- Department of Neurosurgery, Qingdao Huangdao District People's Hospital, Qingdao, 266400, China
| | - Zhangying Wu
- Department of Cardiology, Qingdao Huangdao District People's Hospital, Qingdao, 266400, China
| | - Xianping Zheng
- Intensive Care Unit, Zibo Central Hospital, Zibo, 255024, China
| | - Zhiwei Shao
- Intensive Care Unit, Qingdao Huangdao District People's Hospital, Qingdao, 266400, China
| | - Qiang Lin
- Department of Neurosurgery, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Shoutian Sun
- Department of Emergency, Zibo Central Hospital, No. 54 Gongqingtuan Road, Zhangdian District, Zibo, 255024, China.
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Lynch MA. A case for seeking sex-specific treatments in Alzheimer's disease. Front Aging Neurosci 2024; 16:1346621. [PMID: 38414633 PMCID: PMC10897030 DOI: 10.3389/fnagi.2024.1346621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/15/2024] [Indexed: 02/29/2024] Open
Abstract
There is no satisfactory explanation for the sex-related differences in the incidence of many diseases and this is also true of Alzheimer's disease (AD), where females have a higher lifetime risk of developing the disease and make up about two thirds of the AD patient population. The importance of understanding the cause(s) that account for this disproportionate distribution cannot be overestimated, and is likely to be a significant factor in the search for therapeutic strategies that will combat the disease and, furthermore, potentially point to a sex-targeted approach to treatment. This review considers the literature in the context of what is known about the impact of sex on processes targeted by drugs that are in clinical trial for AD, and existing knowledge on differing responses of males and females to these drugs. Current knowledge strongly supports the view that trials should make assessing sex-related difference in responses a priority with a focus on exploring the sex-stratified treatments.
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Zhong L, Sheng X, Wang W, Li Y, Zhuo R, Wang K, Zhang L, Hu DD, Hong Y, Chen L, Rao H, Li T, Chen M, Lin Z, Zhang YW, Wang X, Yan XX, Chen X, Bu G, Chen XF. TREM2 receptor protects against complement-mediated synaptic loss by binding to complement C1q during neurodegeneration. Immunity 2023; 56:1794-1808.e8. [PMID: 37442133 DOI: 10.1016/j.immuni.2023.06.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 10/22/2022] [Accepted: 06/19/2023] [Indexed: 07/15/2023]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is strongly linked to Alzheimer's disease (AD) risk, but its functions are not fully understood. Here, we found that TREM2 specifically attenuated the activation of classical complement cascade via high-affinity binding to its initiator C1q. In the human AD brains, the formation of TREM2-C1q complexes was detected, and the increased density of the complexes was associated with lower deposition of C3 but higher amounts of synaptic proteins. In mice expressing mutant human tau, Trem2 haploinsufficiency increased complement-mediated microglial engulfment of synapses and accelerated synaptic loss. Administration of a 41-amino-acid TREM2 peptide, which we identified to be responsible for TREM2 binding to C1q, rescued synaptic impairments in AD mouse models. We thus demonstrate a critical role for microglial TREM2 in restricting complement-mediated synaptic elimination during neurodegeneration, providing mechanistic insights into the protective roles of TREM2 against AD pathogenesis.
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Affiliation(s)
- Li Zhong
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China.
| | - Xuan Sheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Wanbing Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Yanzhong Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Rengong Zhuo
- Xiamen Key Laboratory of Chiral Drugs, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, Guangdong, China
| | - Kai Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Lianshuai Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Dan-Dan Hu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Yujuan Hong
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Linting Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Hengjun Rao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Tingting Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Muyang Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Zhihao Lin
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Xin Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, Guangdong, China
| | - Xiao-Xin Yan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha 410013, Hunan, China
| | - Xiaochun Chen
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou 350001, Fujian, China; Fujian Key Laboratory of Molecular Neurology, Institute of Neuroscience, Fujian Medical University, Fuzhou 350001, Fujian, China
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Xiao-Fen Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, Guangdong, China.
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Li M, Ma Y, Fu Y, Liu J, Hu H, Zhao Y, Huang L, Tan L. Association between air pollution and
CSF sTREM2
in cognitively normal older adults: The
CABLE
study. Ann Clin Transl Neurol 2022; 9:1752-1763. [PMID: 36317226 PMCID: PMC9639632 DOI: 10.1002/acn3.51671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/04/2022] [Accepted: 09/16/2022] [Indexed: 11/06/2022] Open
Abstract
Objectives Ambient air pollution aggravates the process of Alzheimer's disease (AD) pathology. Currently, the exact inflammatory mechanisms underlying these links from clinical research remain largely unclear. Methods This study included 1,131 cognitively intact individuals from the Chinese Alzheimer's Biomarker and LifestylE database with data provided on cerebrospinal fluid (CSF) AD biomarkers (amyloid beta‐peptide 42 [Aβ42], total tau [t‐tau], and phosphorylated tau [p‐tau]), neuroinflammatory (CSF sTREM2), and systemic inflammatory markers (high sensitivity C‐reactive protein and peripheral immune cells). The 2‐year averaged levels of ambient fine particulate matter with diameter <2.5 μm (PM2.5), nitrogen dioxide (NO2), and ozone (O3) were estimated at each participant's residence. Multiple‐adjusted models were approached to detect associations of air pollution with inflammatory markers and AD‐related proteins. Results Ambient 2‐year averaged exposure of PM2.5 was associated with changes of neuroinflammatory markers, that is, CSF sTREM2 (β = −0.116, p = 0.0002). Similar results were found for O3 exposure among the elderly (β = −0.111, p = 0.0280) or urban population (β = −0.090, p = 0.0144). No significant evidence supported NO2 related to CSF sTREM2. For potentially causal associations with accumulated AD pathologies, the total effects of PM2.5 on CSF amyloid‐related protein (CSF Aβ42 and p‐tau/Aβ42) were partly mediated by CSF sTREM2, with proportions of 14.22% and 47.15%, respectively. Additional analyses found inverse associations between peripheral inflammatory markers with PM2.5 and NO2, but a positive correlation with O3. Interpretation These findings demonstrated a strong link between PM2.5 exposure and microglial dysfunction. Furthermore, CSF sTREM2 as a key mediator modulated the influences of PM2.5 exposure on AD amyloid pathologies.
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Affiliation(s)
- Meng Li
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - Ya‐Hui Ma
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - Yan Fu
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - Jia‐Yao Liu
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - He‐Ying Hu
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - Yong‐Li Zhao
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - Liang‐Yu Huang
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
| | - Lan Tan
- Department of Neurology Qingdao Municipal Hospital, Qingdao University Qingdao China
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Zhao JF, Ren T, Li XY, Guo TL, Liu CH, Wang X. Research Progress on the Role of Microglia Membrane Proteins or Receptors in Neuroinflammation and Degeneration. Front Cell Neurosci 2022; 16:831977. [PMID: 35281298 PMCID: PMC8913711 DOI: 10.3389/fncel.2022.831977] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/26/2022] [Indexed: 01/01/2023] Open
Abstract
Microglia are intrinsic immune cells of the central nervous system and play a dual role (pro-inflammatory and anti-inflammatory) in the homeostasis of the nervous system. Neuroinflammation mediated by microglia serves as an important stage of ischemic hypoxic brain injury, cerebral hemorrhage disease, neurodegeneration and neurotumor of the nervous system and is present through the whole course of these diseases. Microglial membrane protein or receptor is the basis of mediating microglia to play the inflammatory role and they have been found to be upregulated by recognizing associated ligands or sensing changes in the nervous system microenvironment. They can then allosterically activate the downstream signal transduction and produce a series of complex cascade reactions that can activate microglia, promote microglia chemotactic migration and stimulate the release of proinflammatory factor such as TNF-α, IL-β to effectively damage the nervous system and cause apoptosis of neurons. In this paper, several representative membrane proteins or receptors present on the surface of microglia are systematically reviewed and information about their structures, functions and specific roles in one or more neurological diseases. And on this basis, some prospects for the treatment of novel coronavirus neurological complications are presented.
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Affiliation(s)
- Jun-Feng Zhao
- Department of Neurosurgery, Affiliated Dalian No. 3 People’s Hospital, Dalian Medical University, Dalian, China
| | - Tong Ren
- Department of Neurosurgery, Affiliated Dalian No. 3 People’s Hospital, Dalian Medical University, Dalian, China
| | - Xiang-Yu Li
- Department of Neurosurgery, Affiliated Dalian No. 3 People’s Hospital, Dalian Medical University, Dalian, China
| | - Tian-Lin Guo
- Department of Neurosurgery, Affiliated Dalian No. 3 People’s Hospital, Dalian Medical University, Dalian, China
| | - Chun-Hui Liu
- Department of Neurosurgery, Beijing Tiantan Hospital, Beijing, China
- Chun-Hui Liu,
| | - Xun Wang
- Department of Neurosurgery, Affiliated Dalian No. 3 People’s Hospital, Dalian Medical University, Dalian, China
- *Correspondence: Xun Wang,
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Brown GC, St George-Hyslop P. Does Soluble TREM2 Protect Against Alzheimer's Disease? Front Aging Neurosci 2022; 13:834697. [PMID: 35153729 PMCID: PMC8831327 DOI: 10.3389/fnagi.2021.834697] [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: 12/13/2021] [Accepted: 12/31/2021] [Indexed: 02/02/2023] Open
Abstract
Triggering Receptor Expressed in Myeloid Cells 2 (TREM2) is a pattern recognition receptor on myeloid cells, and is upregulated on microglia surrounding amyloid plaques in Alzheimer's disease (AD). Rare, heterozygous mutations in TREM2 (e.g., R47H) increase AD risk several fold. TREM2 can be cleaved at the plasma membrane by metalloproteases to release the ectodomain as soluble TREM2 (sTREM2). Wild-type sTREM2 binds oligomeric amyloid beta (Aβ) and acts as an extracellular chaperone, blocking and reversing Aβ oligomerization and fibrillization, and preventing Aβ-induced neuronal loss in vitro. Whereas, R47H sTREM2 increases Aβ fibrillization and neurotoxicity. AD brains expressing R47H TREM2 have more fibrous plaques with more neuritic pathology around these plaques, consistent with R47H sTREM2 promoting Aβ fibrillization relative to WT sTREM2. Brain expression or injection of wild-type sTREM2 reduces pathology in amyloid models of AD in mice, indicating that wild-type sTREM2 is protective against amyloid pathology. Levels of sTREM2 in cerebrospinal fluid (CSF) fall prior to AD, rise in early AD, and fall again in late AD. People with higher sTREM2 levels in CSF progress more slowly into and through AD than do people with lower sTREM2 levels, suggesting that sTREM2 protects against AD. However, some of these experiments can be interpreted as full-length TREM2 protecting rather than sTREM2, and to distinguish between these two possibilities, we need more experiments testing whether sTREM2 itself protects in AD and AD models, and at what stage of disease. If sTREM2 is protective, then treatments could be designed to elevate sTREM2 in AD.
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Affiliation(s)
- Guy C. Brown
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom,*Correspondence: Guy C. Brown
| | - Peter St George-Hyslop
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom,Department of Medicine, University of Toronto, Toronto, ON, Canada
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