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Bharadwaj S, Groza Y, Mierzwicka JM, Malý P. Current understanding on TREM-2 molecular biology and physiopathological functions. Int Immunopharmacol 2024; 134:112042. [PMID: 38703564 DOI: 10.1016/j.intimp.2024.112042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/05/2024] [Accepted: 04/05/2024] [Indexed: 05/06/2024]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM-2), a glycosylated receptor belonging to the immunoglobin superfamily and especially expressed in the myeloid cell lineage, is frequently explained as a reminiscent receptor for both adaptive and innate immunity regulation. TREM-2 is also acknowledged to influence NK cell differentiation via the PI3K and PLCγ signaling pathways, as well as the partial activation or direct inhibition of T cells. Additionally, TREM-2 overexpression is substantially linked to cell-specific functions, such as enhanced phagocytosis, reduced toll-like receptor (TLR)-mediated inflammatory cytokine production, increased transcription of anti-inflammatory cytokines, and reshaped T cell function. Whereas TREM-2-deficient cells exhibit diminished phagocytic function and enhanced proinflammatory cytokines production, proceeding to inflammatory injuries and an immunosuppressive environment for disease progression. Despite the growing literature supporting TREM-2+ cells in various diseases, such as neurodegenerative disorders and cancer, substantial facets of TREM-2-mediated signaling remain inadequately understood relevant to pathophysiology conditions. In this direction, herein, we have summarized the current knowledge on TREM-2 biology and cell-specific TREM-2 expression, particularly in the modulation of pivotal TREM-2-dependent functions under physiopathological conditions. Furthermore, molecular regulation and generic biological relevance of TREM-2 are also discussed, which might provide an alternative approach for preventing or reducing TREM-2-associated deformities. At last, we discussed the TREM-2 function in supporting an immunosuppressive cancer environment and as a potential drug target for cancer immunotherapy. Hence, summarized knowledge of TREM-2 might provide a window to overcome challenges in clinically effective therapies for TREM-2-induced diseases in humans.
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Affiliation(s)
- Shiv Bharadwaj
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic.
| | - Yaroslava Groza
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Joanna M Mierzwicka
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Petr Malý
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic.
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2
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Lin C, Kong Y, Chen Q, Zeng J, Pan X, Miao J. Decoding sTREM2: its impact on Alzheimer's disease - a comprehensive review of mechanisms and implications. Front Aging Neurosci 2024; 16:1420731. [PMID: 38912524 PMCID: PMC11190086 DOI: 10.3389/fnagi.2024.1420731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Accepted: 05/30/2024] [Indexed: 06/25/2024] Open
Abstract
Soluble Triggering Receptor Expressed on Myeloid Cells 2 (sTREM2) plays a crucial role in the pathogenesis of Alzheimer's disease (AD). This review comprehensively examines sTREM2's involvement in AD, focusing on its regulatory functions in microglial responses, neuroinflammation, and interactions with key pathological processes. We discuss the dynamic changes in sTREM2 levels in cerebrospinal fluid and plasma throughout AD progression, highlighting its potential as a therapeutic target. Furthermore, we explore the impact of genetic variants on sTREM2 expression and its interplay with other AD risk genes. The evidence presented in this review suggests that modulating sTREM2 activity could influence AD trajectory, making it a promising avenue for future research and drug development. By providing a holistic understanding of sTREM2's multifaceted role in AD, this review aims to guide future studies and inspire novel therapeutic strategies.
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Affiliation(s)
- Cui Lin
- Shenzhen Bao’an District Hospital of Traditional Chinese Medicine, Shenzhen, Guangdong, China
| | - Yu Kong
- Shenzhen Bao’an District Hospital of Traditional Chinese Medicine, Shenzhen, Guangdong, China
| | - Qian Chen
- Shenzhen Bao’an District Hospital of Traditional Chinese Medicine, Shenzhen, Guangdong, China
| | - Jixiang Zeng
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Xiaojin Pan
- Shenzhen Bao’an District Hospital of Traditional Chinese Medicine, Shenzhen, Guangdong, China
| | - Jifei Miao
- Shenzhen Bao’an District Hospital of Traditional Chinese Medicine, Shenzhen, Guangdong, China
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Chiang YK, Lin YS, Chen CY, Lirng JF, Yang YH, Lee WJ, Fuh JL. Different Splice Isoforms of Peripheral Triggering Receptor Expressed on Myeloid Cells 2 mRNA Expressions are Associated With Cognitive Decline in Mild Dementia Due to Alzheimer's Disease and Reflect Central Neuroinflammation. Am J Alzheimers Dis Other Demen 2024; 39:15333175241243183. [PMID: 38592304 PMCID: PMC11005501 DOI: 10.1177/15333175241243183] [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] [Indexed: 04/10/2024]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is upregulated in activated microglia and may be related to cognitive decline in patients with Alzheimer's disease (AD). There is conflicting evidence regarding the association of peripheral TREM2 mRNA expression/soluble TREM2 (the extracellular domain of TREM2) with cognitive function/neuroinflammation in patients with AD. Herein, we studied the TREM2 and TREM2alt mRNA expression and their association with the cognitive performance in subjects with mild dementia due to AD and healthy controls. In a subgroup of patients with AD, magnetic resonance spectroscopy was used to measure the myo-inositol level in the posterior cingulate cortex, a surrogate marker for neuroinflammation. The results showed that increased TREM2 and TREM2alt mRNA expression is associated with AD pathogenesis at the mild dementia stage, thereby serving as a potential biomarker for early symptomatic stage of AD. TREM2 may exert protective effects on both cognition and central neuroinflammation.
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Affiliation(s)
- Yi-Kuan Chiang
- Division of General Neurology, Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yung-Shuan Lin
- Division of General Neurology, Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chun-Yu Chen
- Division of General Neurology, Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Jiing-Feng Lirng
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yu-Hsiu Yang
- Neurological Institute, Taichung Veterans General Hospital, Taichung, Taiwan
- Dementia Center, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Wei-Ju Lee
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Neurological Institute, Taichung Veterans General Hospital, Taichung, Taiwan
- Dementia Center, Taichung Veterans General Hospital, Taichung, Taiwan
- Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Jong-Ling Fuh
- Division of General Neurology, Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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4
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Zhang X, Chen X, Zhang L, Sun Y, Liang Y, Li H, Zhang Y. Role of trigger receptor 2 expressed on myeloid cells in neuroinflammation-neglected multidimensional regulation of microglia. Neurochem Int 2023; 171:105639. [PMID: 37926352 DOI: 10.1016/j.neuint.2023.105639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/01/2023] [Accepted: 11/02/2023] [Indexed: 11/07/2023]
Abstract
Neuroinflammation is an inflammatory cascade involved in various neurological disorders, including Alzheimer's disease, multiple sclerosis, and other relevant diseases. The triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane immune receptor that is primarily expressed by microglia in the central nervous system (CNS). While TREM2 is initially believed to be an anti-inflammatory factor in the CNS, increasing evidence suggests that TREM2 plays a more complex role in balancing neuroinflammation. However, the exact mechanism remains unclear. Notably, TREM2 directly regulates microglia inflammation through various signaling pathways. Additionally, studies have suggested that TREM2 mediates microglial phagocytosis, autophagy, metabolism, and microglia phenotypes, which may be involved in the modulation of neuroinflammation. In this review, we aim to discuss the critical role of TREM2 in several microglia functions and the underlying molecular mechanism the modulatory which further mediate neuroinflammation, and elaborate. Finally, we discuss the potential of TREM2 as a therapeutic target in neuroinflammatory disorders.
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Affiliation(s)
- Xin Zhang
- Department of Respiratory and Critical Care Medicine, Beijing Youan Hospital, Capital Medical University, Beijing, China; Beijing Institute of Hepatology, Beijing Key Laboratory for HIV/AIDS Research, Clinical and Research Center for Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Xue Chen
- Department of Respiratory and Critical Care Medicine, Beijing Youan Hospital, Capital Medical University, Beijing, China; Beijing Institute of Hepatology, Beijing Key Laboratory for HIV/AIDS Research, Clinical and Research Center for Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Ling Zhang
- Department of Respiratory and Critical Care Medicine, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Yuqing Sun
- Department of Respiratory and Critical Care Medicine, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Ying Liang
- Department of Respiratory and Critical Care Medicine, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Huan Li
- Department of Cardiology, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Yulin Zhang
- Department of Respiratory and Critical Care Medicine, Beijing Youan Hospital, Capital Medical University, Beijing, China; Beijing Institute of Hepatology, Beijing Key Laboratory for HIV/AIDS Research, Clinical and Research Center for Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing, China.
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5
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Li Y, Xu H, Wang H, Yang K, Luan J, Wang S. TREM2: Potential therapeutic targeting of microglia for Alzheimer's disease. Biomed Pharmacother 2023; 165:115218. [PMID: 37517293 DOI: 10.1016/j.biopha.2023.115218] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 08/01/2023] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease, resulting in the loss of cognitive ability and memory. However, there is no specific treatment to mechanistically inhibit the progression of Alzheimer's disease, and most drugs only provide symptom relief and do not fundamentally reverse AD. Current studies show that triggering receptor expressed on myeloid cells 2 (TREM2) is predominantly expressed in microglia of the central nervous system (CNS) and is involved in microglia proliferation, survival, migration and phagocytosis. The current academic view suggests that TREM2 and its ligands have CNS protective effects in AD. Specifically, TREM2 acts by regulating the function of microglia and promoting the clearance of neuronal toxic substances and abnormal proteins by microglia. In addition, TREM2 is also involved in regulating inflammatory response and cell signaling pathways, affecting the immune response and regulatory role of microglia. Although the relationship between TREM2 and Alzheimer's disease has been extensively studied, its specific mechanism of action is not fully understood. The purpose of this review is to provide a comprehensive analysis of the research of TREM2, including its regulation of the inflammatory response, lipid metabolism and phagocytosis in microglia of CNS in AD, and to explore the potential application prospects as well as limitations of targeting TREM2 for the treatment of AD.
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Affiliation(s)
- Yueran Li
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Huifang Xu
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Huifang Wang
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Kui Yang
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Jiajie Luan
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Sheng Wang
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China.
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Zhang W, Xiao D, Mao Q, Xia H. Role of neuroinflammation in neurodegeneration development. Signal Transduct Target Ther 2023; 8:267. [PMID: 37433768 PMCID: PMC10336149 DOI: 10.1038/s41392-023-01486-5] [Citation(s) in RCA: 112] [Impact Index Per Article: 112.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 03/22/2023] [Accepted: 05/07/2023] [Indexed: 07/13/2023] Open
Abstract
Studies in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and Amyotrophic lateral sclerosis, Huntington's disease, and so on, have suggested that inflammation is not only a result of neurodegeneration but also a crucial player in this process. Protein aggregates which are very common pathological phenomenon in neurodegeneration can induce neuroinflammation which further aggravates protein aggregation and neurodegeneration. Actually, inflammation even happens earlier than protein aggregation. Neuroinflammation induced by genetic variations in CNS cells or by peripheral immune cells may induce protein deposition in some susceptible population. Numerous signaling pathways and a range of CNS cells have been suggested to be involved in the pathogenesis of neurodegeneration, although they are still far from being completely understood. Due to the limited success of traditional treatment methods, blocking or enhancing inflammatory signaling pathways involved in neurodegeneration are considered to be promising strategies for the therapy of neurodegenerative diseases, and many of them have got exciting results in animal models or clinical trials. Some of them, although very few, have been approved by FDA for clinical usage. Here we comprehensively review the factors affecting neuroinflammation and the major inflammatory signaling pathways involved in the pathogenicity of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis. We also summarize the current strategies, both in animal models and in the clinic, for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Weifeng Zhang
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, P.R. China
| | - Dan Xiao
- The State Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Air Force Medical University, No. 169 Changle West Road, Xi'an, 710032, P.R. China
- Department of Burns and Cutaneous Surgery, Xijing Hospital, Air Force Medical University, No. 169 Changle West Road, Xi'an, 710032, China
| | - Qinwen Mao
- Department of Pathology, University of Utah, Huntsman Cancer Institute, 2000 Circle of Hope Drive, Salt Lake City, UT, 84112, USA
| | - Haibin Xia
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, P.R. China.
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La Rosa F, Agostini S, Piancone F, Marventano I, Hernis A, Fenoglio C, Galimberti D, Scarpini E, Saresella M, Clerici M. TREM2 Expression and Amyloid-Beta Phagocytosis in Alzheimer's Disease. Int J Mol Sci 2023; 24:ijms24108626. [PMID: 37239970 DOI: 10.3390/ijms24108626] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/28/2023] Open
Abstract
Alzheimer's Disease is the most common form of dementia; its key pathological findings include the deposition of extracellular-neurotoxic-plaques composed of amyloid-beta (Ab). AD-pathogenesis involves mechanisms that operate outside the brain, and new researches indicate that peripheral inflammation is an early event in the disease. Herein, we focus on a receptor known as triggering-receptor-expressed-on-myeloid-cells2 (TREM2), which promotes the optimal immune cells function required to attenuate AD-progression and is, therefore, a potential target as peripheral diagnostic and prognostic-biomarker for Alzheimer's Disease. The objective of this exploratory study was to analyze: (1) soluble-TREM2 (sTREM2) plasma and cerebrospinal fluid concentration, (2) TREM2-mRNA, (3) the percentage of TREM2-expressing monocytes, and (4) the concentration of miR-146a-5p and miR-34a-5p suspected to influence TREM2 transcription. Experiments were performed on PBMC collected by 15AD patients and 12age-matched healthy controls that were unstimulated or treated in inflammatory (LPS) conditions and Ab42 for 24 h; Aβ42-phagocytosis was also analyzed by AMNIS FlowSight. Results although preliminary, due to limitations by the small sample-size, showed that in AD compared to HC: TREM2 expressing monocytes were reduced, plasma sTREM2 concentration and TREM2-mRNA were significantly upregulated and Ab42-phagocytosis was diminished (for all p < 0.05). miR-34a-5p expression was reduced (p = 0.02) as well in PBMC of AD, and miR-146 was only observed in AD cells (p = 0.0001).
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Affiliation(s)
| | | | | | | | - Ambra Hernis
- IRCCS Fondazione Don Carlo Gnocchi, 20147 Milan, Italy
| | - Chiara Fenoglio
- Department of Pathophysiology and Transplantation, University of Milan, 20100 Milan, Italy
| | - Daniela Galimberti
- Fondazione Ca' Granda, IRCCS Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, 20100 Milan, Italy
| | - Elio Scarpini
- Fondazione Ca' Granda, IRCCS Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | | | - Mario Clerici
- IRCCS Fondazione Don Carlo Gnocchi, 20147 Milan, Italy
- Department of Pathophysiology and Transplantation, University of Milan, 20100 Milan, Italy
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8
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Peng X, Guo H, Zhang X, Yang Z, Ruganzu JB, Yang Z, Wu X, Bi W, Ji S, Yang W. TREM2 Inhibits Tau Hyperphosphorylation and Neuronal Apoptosis via the PI3K/Akt/GSK-3β Signaling Pathway In vivo and In vitro. Mol Neurobiol 2023; 60:2470-2485. [PMID: 36662361 DOI: 10.1007/s12035-023-03217-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 01/04/2023] [Indexed: 01/21/2023]
Abstract
Triggering receptor expressed on myeloid cells-2 (TREM2), a cell surface receptor mainly expressed on microglia, has been shown to play a critical role in Alzheimer's disease (AD) pathogenesis and progression. Our recent results showed that overexpression of TREM2 inhibited inflammatory response in APP/PS1 mice and BV2 cells. Several studies indicated that TREM2 ameliorated tau hyperphosphorylation might be ascribed to the inhibition of neuroinflammation. However, the precise signaling pathways underlying the effect of TREM2 on tau pathology and neuronal apoptosis have not been fully elucidated. In the present study, upregulation of TREM2 significantly inhibited tau hyperphosphorylation at Ser199, Ser396, and Thr205, respectively, as well as prevented neuronal loss and apoptosis. We also found that upregulation of TREM2 alleviated behavioral deficits and improved the spatial cognitive ability of APP/PS1 mice. Further study revealed that TREM2 could activate phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway, resulting in an inhibitory effect on glycogen synthase kinase-3β (GSK-3β), which is a major kinase responsible for tau hyperphosphorylation in AD. In line with in vivo findings, TREM2-overexpressing BV2 microglia following β-amyloid (Aβ) stimulation led to a significant increase in the phosphorylation of PI3K, Akt, and GSK-3β, accompanied by a decrease in tau hyperphosphorylation and apoptosis in co-cultured SH-SY5Y cells. Furthermore, LY294002, a specific PI3K inhibitor, was observed to abolish the beneficial effects of TREM2 on tau hyperphosphorylation, neuronal apoptosis, and spatial cognitive impairments in vivo and in vitro. Thus, our findings indicated that TREM2 inhibits tau hyperphosphorylation and neuronal apoptosis, at least in part, by the activation of the PI3K/Akt/GSK-3β signaling pathway. Taken together, the above results allow us to better understand how TREM2 protects against tau pathology and suggest that upregulation of TREM2 may provide new ideas and therapeutic targets for AD.
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Affiliation(s)
- Xiaoqian Peng
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Hongsong Guo
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Xiao Zhang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Zikang Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Qide College, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - John Bosco Ruganzu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Zhuoyuan Yang
- Medical Undergraduates of the Second Clinical Medical School of Xi'an Medical University, Xi'an, 710038, Shaanxi, China
| | - Xiangyuan Wu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Wei Bi
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Shengfeng Ji
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Weina Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China.
- Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China.
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9
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Moutinho M, Coronel I, Tsai AP, Di Prisco GV, Pennington T, Atwood BK, Puntambekar SS, Smith DC, Martinez P, Han S, Lee Y, Lasagna-Reeves CA, Lamb BT, Bissel SJ, Nho K, Landreth GE. TREM2 splice isoforms generate soluble TREM2 species that disrupt long-term potentiation. Genome Med 2023; 15:11. [PMID: 36805764 PMCID: PMC9940368 DOI: 10.1186/s13073-023-01160-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 02/03/2023] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND TREM2 is a transmembrane receptor expressed by myeloid cells and acts to regulate their immune response. TREM2 governs the response of microglia to amyloid and tau pathologies in the Alzheimer's disease (AD) brain. TREM2 is also present in a soluble form (sTREM2), and its CSF levels fluctuate as a function of AD progression. Analysis of stroke and AD mouse models revealed that sTREM2 proteins bind to neurons, which suggests sTREM2 may act in a non-cell autonomous manner to influence neuronal function. sTREM2 arises from the proteolytic cleavage of the membrane-associated receptor. However, alternatively spliced TREM2 species lacking a transmembrane domain have been postulated to contribute to the pool of sTREM2. Thus, both the source of sTREM2 species and its actions in the brain remain unclear. METHODS The expression of TREM2 isoforms in the AD brain was assessed through the analysis of the Accelerating Medicines Partnership for Alzheimer's Disease Consortium transcriptomics data, as well as qPCR analysis using post-mortem samples of AD patients and of the AD mouse model 5xFAD. TREM2 cleavage and secretion were studied in vitro using HEK-293T and HMC3 cell lines. Synaptic plasticity, as evaluated by induction of LTP in hippocampal brain slices, was employed as a measure of sTREM2 actions. RESULTS Three distinct TREM2 transcripts, namely ENST00000373113 (TREM2230), which encodes the full-length transmembrane receptor, and the alternatively spliced isoforms ENST00000373122 (TREM2222) and ENST00000338469 (TREM2219), are moderately increased in specific brain regions of patients with AD. We provide experimental evidence that TREM2 alternatively spliced isoforms are translated and secreted as sTREM2. Furthermore, our functional analysis reveals that all sTREM2 species inhibit LTP induction, and this effect is abolished by the GABAA receptor antagonist picrotoxin. CONCLUSIONS TREM2 transcripts can give rise to a heterogeneous pool of sTREM2 which acts to inhibit LTP. These results provide novel insight into the generation, regulation, and function of sTREM2 which fits into the complex biology of TREM2 and its role in human health and disease. Given that sTREM2 levels are linked to AD pathogenesis and progression, our finding that sTREM2 species interfere with LTP furthers our understanding about the role of TREM2 in AD.
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Affiliation(s)
- Miguel Moutinho
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Israel Coronel
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Andy P Tsai
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gonzalo Viana Di Prisco
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Pharmacology and Toxicology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Taylor Pennington
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Pharmacology and Toxicology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Brady K Atwood
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Pharmacology and Toxicology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Shweta S Puntambekar
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel C Smith
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Pablo Martinez
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Seonggyun Han
- Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Younghee Lee
- Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Cristian A Lasagna-Reeves
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Bruce T Lamb
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Stephanie J Bissel
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kwangsik Nho
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Radiology and Imaging Sciences, Indiana Alzheimer's Disease Research Center, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gary E Landreth
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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10
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The Interplay between α-Synuclein and Microglia in α-Synucleinopathies. Int J Mol Sci 2023; 24:ijms24032477. [PMID: 36768798 PMCID: PMC9916729 DOI: 10.3390/ijms24032477] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/19/2023] [Accepted: 01/24/2023] [Indexed: 02/01/2023] Open
Abstract
Synucleinopathies are a set of devastating neurodegenerative diseases that share a pathologic accumulation of the protein α-synuclein (α-syn). This accumulation causes neuronal death resulting in irreversible dementia, deteriorating motor symptoms, and devastating cognitive decline. While the etiology of these conditions remains largely unknown, microglia, the resident immune cells of the central nervous system (CNS), have been consistently implicated in the pathogenesis of synucleinopathies. Microglia are generally believed to be neuroprotective in the early stages of α-syn accumulation and contribute to further neurodegeneration in chronic disease states. While the molecular mechanisms by which microglia achieve this role are still being investigated, here we highlight the major findings to date. In this review, we describe how structural varieties of inherently disordered α-syn result in varied microglial receptor-mediated interactions. We also summarize which microglial receptors enable cellular recognition and uptake of α-syn. Lastly, we review the downstream effects of α-syn processing within microglia, including spread to other brain regions resulting in neuroinflammation and neurodegeneration in chronic disease states. Understanding the mechanism of microglial interactions with α-syn is vital to conceptualizing molecular targets for novel therapeutic interventions. In addition, given the significant diversity in the pathophysiology of synucleinopathies, such molecular interactions are vital in gauging all potential pathways of neurodegeneration in the disease state.
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11
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Profile of TREM2-Derived circRNA and mRNA Variants in the Entorhinal Cortex of Alzheimer’s Disease Patients. Int J Mol Sci 2022; 23:ijms23147682. [PMID: 35887031 PMCID: PMC9320643 DOI: 10.3390/ijms23147682] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/04/2022] [Accepted: 07/04/2022] [Indexed: 02/04/2023] Open
Abstract
Genetic variants in TREM2, a microglia-related gene, are well-known risk factors for Alzheimer’s disease (AD). Here, we report that TREM2 originates from circular RNAs (circRNAs), a novel class of non-coding RNAs characterized by a covalent and stable closed-loop structure. First, divergent primers were designed to amplify circRNAs by RT-PCR, which were further assessed by Sanger sequencing. Then, additional primer sets were used to confirm back-splicing junctions. In addition, HMC3 cells were used to assess the microglial expression of circTREM2s. Three candidate circTREM2s were identified in control and AD human entorhinal samples. One of the circRNAs, circTREM2_1, was consistently amplified by all divergent primer sets in control and AD entorhinal cortex samples as well as in HMC3 cells. In AD cases, a moderate negative correlation (r = −0.434) was found between the global average area of Aβ deposits in the entorhinal cortex and circTREM2_1 expression level. In addition, by bioinformatics tools, a total of 16 miRNAs were predicted to join with circTREM2s. Finally, TREM2 mRNA corresponding to four isoforms was profiled by RT-qPCR. TREM2 mRNA levels were found elevated in entorhinal samples of AD patients with low or intermediate ABC scores compared to controls. To sum up, a novel circRNA derived from the TREM2 gene, circTREM2_1, has been identified in the human entorhinal cortex and TREM2 mRNA expression has been detected to increase in AD compared to controls. Unraveling the molecular genetics of the TREM2 gene may help to better know the innate immune response in AD.
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12
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Pradhan LK, Sahoo PK, Chauhan S, Das SK. Recent Advances Towards Diagnosis and Therapeutic Fingerprinting for Alzheimer's Disease. J Mol Neurosci 2022; 72:1143-1165. [PMID: 35553375 DOI: 10.1007/s12031-022-02009-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/02/2022] [Indexed: 12/12/2022]
Abstract
Since the report of "a peculiar severe disease process of the cerebral cortex" by Alois Alzheimer in 1906, it was considered to be a rare condition characterized by loss of cognition, memory impairment, and pathological markers such as senile plaques or neurofibrillary tangles (NFTs). Later on, the report was published in the textbook "Psychiatrie" and the disease was named as Alzheimer's disease (AD) and was known to be the consequences of aging; however, owing to its complex etiology, there is no cure for the progressive neurodegenerative disorder. Our current understanding of the mechanisms involved in the pathogenesis of AD is still at the mechanistic level. The treatment strategies applied currently only alleviate the symptoms and co-morbidities. For instance, the available treatments such as the usage of acetylcholinesterase inhibitors and N-methyl D-aspartate antagonists have minimal impact on the disease progression and target the later aspects of the disease. The recent advancements in the last two decades have made us more clearly understand the pathophysiology of the disease which has led to the development of novel therapeutic strategies. This review gives a brief idea about the various facets of AD pathophysiology and its management through modern investigational therapies to give a new direction for development of targeted therapeutic measures.
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Affiliation(s)
- Lilesh Kumar Pradhan
- Neurobiology Laboratory, Centre for Biotechnology, Siksha 'O' Anusandhan (Deemed to Be University), Kalinga Nagar, Bhubaneswar-751003, India
| | - Pradyumna Kumar Sahoo
- Neurobiology Laboratory, Centre for Biotechnology, Siksha 'O' Anusandhan (Deemed to Be University), Kalinga Nagar, Bhubaneswar-751003, India
| | - Santosh Chauhan
- Autophagy Laboratory, Infectious Disease Biology Division, Institute of Life Sciences, Bhubaneswar-751023, India.
| | - Saroj Kumar Das
- Neurobiology Laboratory, Centre for Biotechnology, Siksha 'O' Anusandhan (Deemed to Be University), Kalinga Nagar, Bhubaneswar-751003, India.
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13
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Variant TREM2 Signaling in Alzheimer's Disease. J Mol Biol 2022; 434:167470. [PMID: 35120968 DOI: 10.1016/j.jmb.2022.167470] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/25/2022] [Accepted: 01/27/2022] [Indexed: 12/25/2022]
Abstract
Alzheimer's disease is the most common form of dementia, accounting for as much as three-quarters of cases globally with individuals in low- and middle-income countries being worst affected. Numerous risk factors for the disease have been identified and our understanding of gene-environment interactions have shed light on several gene variants that contribute to the most common, sporadic form of Alzheimer's disease. Triggering Receptor Expressed on Myeloid cells 2 (TREM2) is an important receptor that is crucial to the functioning of microglial cells, and variants of this protein have been found to be associated with a significantly increased risk of Alzheimer's disease. Several studies have elucidated the signaling processes involved in the normal functioning of the TREM2 receptor. However, current knowledge of the idiosyncrasies of the signaling processes triggered by stimulation of the variants of this receptor is limited. In this review, we examine the existing literature and highlight the effects that various receptor variants have on downstream signaling processes and discuss how these perturbations may affect physiologic processes in Alzheimer's disease. Despite the fact that this is a territory yet to be fully explored, the studies that currently exist report mostly quantitative effects on signaling. More mechanistic studies with the aim of providing qualitative results in terms of downstream signaling among these receptor variants are warranted. Such studies will provide better opportunities of identifying therapeutic targets that may be exploited in designing new drugs for the management of Alzheimer's disease.
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14
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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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15
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Ruganzu JB, Peng X, He Y, Wu X, Zheng Q, Ding B, Lin C, Guo H, Yang Z, Zhang X, Yang W. Downregulation of TREM2 expression exacerbates neuroinflammatory responses through TLR4-mediated MAPK signaling pathway in a transgenic mouse model of Alzheimer's disease. Mol Immunol 2021; 142:22-36. [PMID: 34959070 DOI: 10.1016/j.molimm.2021.12.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 12/20/2022]
Abstract
Activation of glial cells and neuroinflammation play an important role in the onset and development of Alzheimer's disease (AD). Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglia-specific receptor in the brain that is involved in regulating neuroinflammation. However, the precise effects of TREM2 on neuroinflammatory responses and its underlying molecular mechanisms in AD have not been studied in detail. Here, we employed a lentiviral-mediated strategy to downregulation of TREM2 expression on microglia in the brain of APPswe/PS1dE9 (APP/PS1) transgenic mice and BV2 cells. Our results showed that downregulation of TREM2 significantly aggravated AD-related neuropathology including Aβ accumulation, peri-plaque microgliosis and astrocytosis, as well as neuronal and synapse-associated proteins loss, which was accompanied by a decline in cognitive ability. The further mechanistic study revealed that downregulation of TREM2 expression initiated neuroinflammatory responses through toll-like receptor 4 (TLR4)-mediated mitogen-activated protein kinase (MAPK) signaling pathway and subsequent stimulating the production of pro-inflammatory cytokines in vivo and in vitro. Moreover, blockade of p38, JNK, and ERK1/2 inhibited the release of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) induced by Aβ1-42 in TREM2-knocked down BV2 cells. Taken together, these findings indicated that TREM2 might be a potential therapeutic target for AD and other neuroinflammation-related diseases.
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Affiliation(s)
- John Bosco Ruganzu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Xiaoqian Peng
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Yingying He
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Xiangyuan Wu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Quzhao Zheng
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Bo Ding
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Chengheng Lin
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Hongsong Guo
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Zikang Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Xiao Zhang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Weina Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China.
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16
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Wang Q, Yao H, Liu W, Ya B, Cheng H, Xing Z, Wu Y. Microglia Polarization in Alzheimer's Disease: Mechanisms and a Potential Therapeutic Target. Front Aging Neurosci 2021; 13:772717. [PMID: 34819850 PMCID: PMC8606412 DOI: 10.3389/fnagi.2021.772717] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/07/2021] [Indexed: 11/13/2022] Open
Abstract
Neuroinflammation regulated by microglia is one of the important factors involved in the pathogenesis of Alzheimer’s disease (AD). Activated microglia exhibited phenotypes termed as M1 and M2 phenotypes separately. M1 microglia contribute to the development of inflammation via upregulating pro-inflammatory cytokines, while M2 microglia exert anti-inflammation effects through enhancing the expression of anti-inflammation factors. Moreover, M1 and M2 microglia could be mutually transformed under various conditions. Both M1 and M2 microglia are implicated in AD. Amyloid-β (Aβ) and hyperphosphorylated tau are two major components of AD pathological hallmarks, neuritic plaques, and neurofibrillary tangles. Both Aβ and hyperphosphorylated tau were involved in microglial activation and subsequent inflammation, which further contribute to neuronal and synaptic loss in AD. In this review, we summarized the roles of M1 and M2 microglia in AD and underlying mechanisms, which will provide an insight into the role of microglia in the pathogenesis of AD and highlight the therapeutic potential of modulating microglia.
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Affiliation(s)
- Qinqin Wang
- Shandong Collaborative Innovation Center for Diagnosis, Treatment and Behavioral Interventions of Mental Disorders, Institute of Mental Health, Jining Medical University, Jining, China
| | - Hongmei Yao
- Affiliated Hospital of Jining Medical University, Jining, China
| | - Wenyan Liu
- Department of Physiology, College of Basic Medicine, Jining Medical University, Jining, China
| | - Bailiu Ya
- Department of Physiology, College of Basic Medicine, Jining Medical University, Jining, China
| | - Hongju Cheng
- Department of Physiology, College of Basic Medicine, Jining Medical University, Jining, China
| | - Zhenkai Xing
- Shandong Collaborative Innovation Center for Diagnosis, Treatment and Behavioral Interventions of Mental Disorders, Institute of Mental Health, Jining Medical University, Jining, China
| | - Yili Wu
- The Affiliated Kangning Hospital, Wenzhou Medical University, Wenzhou, China.,Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, School of Mental Health, Wenzhou Medical University, Wenzhou, China.,Oujiang Laboratory, Wenzhou, China
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17
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Karahan H, Smith DC, Kim B, Dabin LC, Al-Amin MM, Wijeratne HRS, Pennington T, Viana di Prisco G, McCord B, Lin PBC, Li Y, Peng J, Oblak AL, Chu S, Atwood BK, Kim J. Deletion of Abi3 gene locus exacerbates neuropathological features of Alzheimer's disease in a mouse model of Aβ amyloidosis. SCIENCE ADVANCES 2021; 7:eabe3954. [PMID: 34731000 PMCID: PMC8565913 DOI: 10.1126/sciadv.abe3954] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 09/16/2021] [Indexed: 05/02/2023]
Abstract
Recently, large-scale human genetics studies identified a rare coding variant in the ABI3 gene that is associated with an increased risk of Alzheimer’s disease (AD). However, pathways by which ABI3 contributes to the pathogenesis of AD are unknown. To address this question, we determined whether loss of ABI3 function affects pathological features of AD in the 5XFAD mouse model. We demonstrate that the deletion of Abi3 locus significantly increases amyloid β (Aβ) accumulation and decreases microglia clustering around the plaques. Furthermore, long-term potentiation is impaired in 5XFAD;Abi3 knockout (“Abi3−/−”) mice. Moreover, we identified marked changes in the proportion of microglia subpopulations in Abi3−/− mice using a single-cell RNA sequencing approach. Mechanistic studies demonstrate that Abi3 knockdown in microglia impairs migration and phagocytosis. Together, our study provides the first in vivo functional evidence that loss of ABI3 function may increase the risk of developing AD by affecting Aβ accumulation and neuroinflammation.
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Affiliation(s)
- Hande Karahan
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Daniel C. Smith
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Byungwook Kim
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Luke C. Dabin
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Md Mamun Al-Amin
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - H. R. Sagara Wijeratne
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Taylor Pennington
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Gonzalo Viana di Prisco
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Brianne McCord
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Peter Bor-chian Lin
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yuxin Li
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Junmin Peng
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Adrian L. Oblak
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Shaoyou Chu
- Division of Clinical Pharmacology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Brady K. Atwood
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Jungsu Kim
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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18
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Okuzono Y, Sakuma H, Miyakawa S, Ifuku M, Lee J, Das D, Banerjee A, Zhao Y, Yamamoto K, Ando T, Sato S. Reduced TREM2 activation in microglia of patients with Alzheimer's disease. FEBS Open Bio 2021; 11:3063-3080. [PMID: 34523252 PMCID: PMC8564098 DOI: 10.1002/2211-5463.13300] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 08/27/2021] [Accepted: 09/13/2021] [Indexed: 12/13/2022] Open
Abstract
Loss-of-function variants of triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk of developing Alzheimer's disease (AD). The mechanism through which TREM2 contributes to the disease (TREM2 activation vs inactivation) is largely unknown. Here, we analyzed changes in a gene set downstream of TREM2 to determine whether TREM2 signaling is modified by AD progression. We generated an anti-human TREM2 agonistic antibody and defined TREM2 activation in terms of the downstream expression changes induced by this antibody in microglia developed from human induced pluripotent stem cells (iPSC). Differentially expressed genes (DEGs) following TREM2 activation were compared with the gene set extracted from microglial single nuclear RNA sequencing data of patients with AD, using gene set enrichment analysis. We isolated an anti-TREM2-specific agonistic antibody, Hyb87, from anti-human TREM2 antibodies generated using binding and agonism assays, which helped us identify 300 upregulated and 251 downregulated DEGs. Pathway enrichment analysis suggested that TREM2 activation may be associated with Th2-related pathways. TREM2 activation was lower in AD microglia than in microglia from healthy subjects or patients with mild cognitive impairment. TREM2 activation also showed a significant negative correlation with disease progression. Pathway enrichment analysis of DEGs controlled by TREM2 activity indicated that TREM2 activation in AD may lead to anti-apoptotic signaling, immune response, and cytoskeletal changes in the microglia. We showed that TREM2 activation decreases with AD progression, in support of a protective role of TREM2 activation in AD. In addition, the agonistic anti-TREM2 antibody can be used to identify TREM2 activation state in AD microglia.
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Affiliation(s)
- Yuumi Okuzono
- Immune Cell Engineered TherapeuticsResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Hiroyuki Sakuma
- Neuroscience Drug Discovery UnitResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Shuuichi Miyakawa
- Immune Cell Engineered TherapeuticsResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Masataka Ifuku
- Immune Cell Engineered TherapeuticsResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Jonghun Lee
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Debashree Das
- Early Target DiscoveryResearch, Takeda California, Inc.San DiegoCAUSA
| | - Antara Banerjee
- GI ImmunologyResearch, Takeda California, Inc.San DiegoCAUSA
| | - Yang Zhao
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Koji Yamamoto
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Tatsuya Ando
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Shuji Sato
- Neuroscience Drug Discovery UnitResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
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19
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Moutinho M, Landreth GE. TREM2 splicing emerges as crucial aspect to understand TREM2 biology. J Leukoc Biol 2021; 110:827-828. [PMID: 34312904 DOI: 10.1002/jlb.2ce0521-264r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/12/2021] [Accepted: 07/14/2021] [Indexed: 11/05/2022] Open
Abstract
Discussion on TREM2 splicing and its different transcripts with regard to the physiological function of TREM2 and its role in disease.
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Affiliation(s)
- Miguel Moutinho
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Gary E Landreth
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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20
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Role of TREM2 in Alzheimer's Disease: A Long Road Ahead. Mol Neurobiol 2021; 58:5239-5252. [PMID: 34275100 DOI: 10.1007/s12035-021-02477-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by an increasing deterioration of memory, which is concomitant with additional cognitive deficits. Neurofibrillary tangles and senile plaques are two pivotal proteins inside the brain that are considered essential to obstruct the normal cognitive function of the brain. Genetic variations in TREM2 gene disturb the neuroinflammatory action of microglia in reducing the progression of the disease.TREM2 is a transmembrane receptor present on the microglia, which has an important function in neuroinflammation. Genome-wide association studies identified variants of TREM2 gene and linked it with the risk of developing AD, by 2-4 folds. Numerous studies on mice models have revealed the relationship between mutations of TREM2 gene and its effect on amyloid burden and tau pathology in the brain that gets affected by AD. This review summarizes the role of TREM2 and its variants in the progression of AD and tries to delve deep into the role of soluble TREM2 as an effective biomarker and impending neuroprotection in AD. It also focuses on the strategies to develop therapeutic agents against TREM2 by employing its expression, function, and signalling pathways. The current challenges posed against prospective therapy for AD are also discussed.
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21
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Schoch KM, Ezerskiy LA, Morhaus MM, Bannon RN, Sauerbeck AD, Shabsovich M, Jafar-Nejad P, Rigo F, Miller TM. Acute Trem2 reduction triggers increased microglial phagocytosis, slowing amyloid deposition in mice. Proc Natl Acad Sci U S A 2021; 118:e2100356118. [PMID: 34187891 PMCID: PMC8271763 DOI: 10.1073/pnas.2100356118] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Heterozygous genetic variants within the TREM2 gene show a strong association with increased Alzheimer's disease (AD) risk. Amyloid beta-depositing mouse models haploinsufficient or null for Trem2 have identified important relationships among TREM2, microglia, and AD pathology; however, results are challenging to interpret in the context of varying microglial phenotypes and disease progression. We hypothesized that acute Trem2 reduction may alter amyloid pathology and microglial responses independent of genetic Trem2 deletion in mouse models. We developed antisense oligonucleotides (ASOs) that potently but transiently lower Trem2 messenger RNA throughout the brain and administered them to APP/PS1 mice at varying stages of plaque pathology. Late-stage ASO-mediated Trem2 knockdown significantly reduced plaque deposition and attenuated microglial association around plaque deposits when evaluated 1 mo after ASO injection. Changes in microglial gene signatures 1 wk after ASO administration and phagocytosis measured in ASO-treated cells together indicate that microglia may be activated with short-term Trem2 reduction. These results suggest a time- and/or dose-dependent role for TREM2 in mediating plaque deposition and microglial responses in which loss of TREM2 function may be beneficial for microglial activation and plaque removal in an acute context.
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Affiliation(s)
- Kathleen M Schoch
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110;
| | - Lubov A Ezerskiy
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110
| | - Michaela M Morhaus
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110
| | - Riley N Bannon
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110
| | - Andrew D Sauerbeck
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110
| | - Mark Shabsovich
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110
| | | | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92010
| | - Timothy M Miller
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110;
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22
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Cosker K, Mallach A, Limaye J, Piers TM, Staddon J, Neame SJ, Hardy J, Pocock JM. Microglial signalling pathway deficits associated with the patient derived R47H TREM2 variants linked to AD indicate inability to activate inflammasome. Sci Rep 2021; 11:13316. [PMID: 34172778 PMCID: PMC8233372 DOI: 10.1038/s41598-021-91207-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/20/2021] [Indexed: 02/05/2023] Open
Abstract
The R47H variant of the microglial membrane receptor TREM2 is linked to increased risk of late onset Alzheimer's disease. Human induced pluripotent stem cell derived microglia (iPS-Mg) from patient iPSC lines expressing the AD-linked R47Hhet TREM2 variant, common variant (Cv) or an R47Hhom CRISPR edited line and its isogeneic control, demonstrated that R47H-expressing iPS-Mg expressed a deficit in signal transduction in response to the TREM2 endogenous ligand phosphatidylserine with reduced pSYK-pERK1/2 signalling and a reduced NLRP3 inflammasome response, (including ASC speck formation, Caspase-1 activation and IL-1beta secretion). Apoptotic cell phagocytosis and soluble TREM2 shedding were unaltered, suggesting a disjoint between these pathways and the signalling cascades downstream of TREM2 in R47H-expressing iPS-Mg, whilst metabolic deficits in glycolytic capacity and maximum respiration were reversed when R47H expressing iPS-Mg were exposed to PS+ expressing cells. These findings suggest that R47H-expressing microglia are unable to respond fully to cell damage signals such as phosphatidylserine, which may contribute to the progression of neurodegeneration in late-onset AD.
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Affiliation(s)
- Katharina Cosker
- grid.83440.3b0000000121901201Department of Neuroinflammation, University College London, Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ UK
| | - Anna Mallach
- grid.83440.3b0000000121901201Department of Neuroinflammation, University College London, Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ UK
| | - Janhavi Limaye
- grid.83440.3b0000000121901201Department of Neuroinflammation, University College London, Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ UK
| | - Thomas M. Piers
- grid.83440.3b0000000121901201Department of Neuroinflammation, University College London, Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ UK
| | - James Staddon
- grid.428696.7Eisai Ltd, Mosquito Way, Hatfield, AL10 9SN UK
| | | | - John Hardy
- grid.436283.80000 0004 0612 2631Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG UK ,grid.83440.3b0000000121901201Dementia Research Institute, University College, London, UCL, Reta Lila Weston Institute, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ UK ,grid.24515.370000 0004 1937 1450NIHR University College London Hospitals Biomedical Research Centre and Institute for Advanced Study, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Jennifer M. Pocock
- grid.83440.3b0000000121901201Department of Neuroinflammation, University College London, Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ UK
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23
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Vieira SRL, Morris HR. Neurodegenerative Disease Risk in Carriers of Autosomal Recessive Disease. Front Neurol 2021; 12:679927. [PMID: 34149605 PMCID: PMC8211888 DOI: 10.3389/fneur.2021.679927] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/14/2021] [Indexed: 01/19/2023] Open
Abstract
Genetics has driven significant discoveries in the field of neurodegenerative diseases (NDDs). An emerging theme in neurodegeneration warrants an urgent and comprehensive update: that carrier status of early-onset autosomal recessive (AR) disease, typically considered benign, is associated with an increased risk of a spectrum of late-onset NDDs. Glucosylceramidase beta (GBA1) gene mutations, responsible for the AR lysosomal storage disorder Gaucher disease, are a prominent example of this principle, having been identified as an important genetic risk factor for Parkinson disease. Genetic analyses have revealed further examples, notably GRN, TREM2, EIF2AK3, and several other LSD and mitochondria function genes. In this Review, we discuss the evidence supporting the strikingly distinct allele-dependent clinical phenotypes observed in carriers of such gene mutations and its impact on the wider field of neurodegeneration.
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Affiliation(s)
| | - Huw R. Morris
- Department of Clinical and Movement Neurosciences, University College London, Queen Square Institute of Neurology, London, United Kingdom
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24
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Diaz-Lucena D, Kruse N, Thüne K, Schmitz M, Villar-Piqué A, da Cunha JEG, Hermann P, López-Pérez Ó, Andrés-Benito P, Ladogana A, Calero M, Vidal E, Riggert J, Pineau H, Sim V, Zetterberg H, Blennow K, Del Río JA, Marín-Moreno A, Espinosa JC, Torres JM, Sánchez-Valle R, Mollenhauer B, Ferrer I, Zerr I, Llorens F. TREM2 expression in the brain and biological fluids in prion diseases. Acta Neuropathol 2021; 141:841-859. [PMID: 33881612 PMCID: PMC8113222 DOI: 10.1007/s00401-021-02296-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/15/2021] [Accepted: 03/15/2021] [Indexed: 12/19/2022]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is an innate immune cell surface receptor that regulates microglial function and is involved in the pathophysiology of several neurodegenerative diseases. Its soluble form (sTREM2) results from shedding of the TREM2 ectodomain. The role of TREM2 in prion diseases, a group of rapidly progressive dementias remains to be elucidated. In the present study, we analysed the expression of TREM2 and its main sheddase ADAM10 in the brain of sporadic Creutzfeldt-Jakob disease (sCJD) patients and evaluated the role of CSF and plasma sTREM2 as a potential diagnostic marker of prion disease. Our data indicate that, compared to controls, TREM2 is increased in sCJD patient brains at the mRNA and protein levels in a regional and subtype dependent fashion, and expressed in a subpopulation of microglia. In contrast, ADAM10 is increased at the protein, but not the mRNA level, with a restricted neuronal expression. Elevated CSF sTREM2 is found in sCJD, genetic CJD with mutations E200K and V210I in the prion protein gene (PRNP), and iatrogenic CJD, as compared to healthy controls (HC) (AUC = 0.78–0.90) and neurological controls (AUC = 0.73–0.85), while CSF sTREM2 is unchanged in fatal familial insomnia. sTREM2 in the CSF of cases with Alzheimer’s disease, and multiple sclerosis was not significantly altered in our series. CSF sTREM2 concentrations in sCJD are PRNP codon 129 and subtype-related, correlate with CSF 14-3-3 positivity, total-tau and YKL-40, and increase with disease progression. In plasma, sTREM2 is increased in sCJD compared with HC (AUC = 0.80), displaying positive correlations with plasma total-tau, neurofilament light, and YKL-40. We conclude that comparative study of TREM2 in brain and biological fluids of prion diseases reveals TREM2 to be altered in human prion diseases with a potential value in target engagement, patient stratification, and disease monitoring.
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Affiliation(s)
- Daniela Diaz-Lucena
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), L'Hospitalet de Llobregat, Spain
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Niels Kruse
- University Medical Center Göttingen, Institute of Neuropathology, Göttingen, Germany
| | - Katrin Thüne
- Department of Neurology, University Medical Center Göttingen, Gern August University, Robert Koch Strasse 40, 37075, Göttingen, Germany
| | - Matthias Schmitz
- Department of Neurology, University Medical Center Göttingen, Gern August University, Robert Koch Strasse 40, 37075, Göttingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany
| | - Anna Villar-Piqué
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), L'Hospitalet de Llobregat, Spain
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | | | - Peter Hermann
- Department of Neurology, University Medical Center Göttingen, Gern August University, Robert Koch Strasse 40, 37075, Göttingen, Germany
| | - Óscar López-Pérez
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), L'Hospitalet de Llobregat, Spain
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Pol Andrés-Benito
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), L'Hospitalet de Llobregat, Spain
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Anna Ladogana
- Department of Neurosciences, Istituto Superiore Di Sanità, Rome, Italy
| | - Miguel Calero
- Alzheimer Disease Research Unit, CIEN Foundation, Chronic Disease Programme, Queen Sofia Foundation Alzheimer Center, Instituto de Salud Carlos III, Madrid, Spain
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Enric Vidal
- Centre de Recerca en Sanitat Animal, Campus Universitat Autònoma de Barcelona, Institut de Recerca I Tecnologia Agroalimentàries, Bellaterra, Spain
| | - Joachim Riggert
- Department of Transfusion Medicine, University Medical School, Göttingen, Germany
| | - Hailey Pineau
- Department of Medicine-Division of Neurology, Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Valerie Sim
- Department of Medicine-Division of Neurology, Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Institute of Neuroscience and Physiology, Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London, UK
- UK Dementia Research Institute, London, UK
| | - Kaj Blennow
- Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Institute of Neuroscience and Physiology, Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Jose Antonio Del Río
- Molecular and Cellular Neurobiotechnology, Scientific Park of Barcelona, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
- University of Barcelona, Institute of Neuroscience, Barcelona, Spain
| | | | | | | | - Raquel Sánchez-Valle
- Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clinic de Barcelona, Institut D'Investigacions Biomediques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
| | - Brit Mollenhauer
- Paracelsus-Elena Klinik, Kassel, Germany
- Department of Neurology, University Medical Centre Göttingen, Göttingen, Germany
| | - Isidre Ferrer
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), L'Hospitalet de Llobregat, Spain.
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain.
- Department of Pathology and Experimental Therapeutics, Hospitalet de Llobregat, University of Barcelona, Feixa Llarga S/N, 08907, Barcelona, Spain.
| | - Inga Zerr
- Department of Neurology, University Medical Center Göttingen, Gern August University, Robert Koch Strasse 40, 37075, Göttingen, Germany.
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany.
| | - Franc Llorens
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), L'Hospitalet de Llobregat, Spain
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
- Department of Neurology, University Medical Center Göttingen, Gern August University, Robert Koch Strasse 40, 37075, Göttingen, Germany
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25
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Shafi S, Singh A, Ibrahim AM, Alhajri N, Abu Izneid T, Pottoo FH. Role of triggering receptor expressed on myeloid cells 2 (TREM2) in neurodegenerative dementias. Eur J Neurosci 2021; 53:3294-3310. [PMID: 33786894 DOI: 10.1111/ejn.15215] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 03/22/2021] [Indexed: 01/04/2023]
Abstract
Neurodegeneration is a debilitating condition that causes nerve cell degeneration or death. Neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD), and Lewy body dementia (LBD) are posing a larger population burden of dementia worldwide. Neurodegenerative dementia is one of the main challenges in public health with its main characteristics being permanent loss of memory, impairment in cognition, and impaired daily functions. The published literature about genetic studies of these disorders suggests genetic underpinning in the pathogenesis of neurodegenerative dementia. In the process of underlining the pathogenesis of NDD, growing evidence has related genetic variations in the triggering receptor expressed on myeloid cells 2 (TREM2). This review paper aims to provide a detailed information regarding the association of TREM2 and NDDs leading to dementia. A central consideration is AD that accounts for almost 50%-70% of all late-life dementias alone or in combination with other neurological disorders. Other prevalent neurodegenerative conditions that lead to dementia are also discussed. Such studies are important as they can give a comprehensive knowledge of TREM2's role in various NDDs, in order to maximize the potential for developing new therapeutic approaches.
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Affiliation(s)
- Sadat Shafi
- Pharmaceutical Medicine, Department of Pharmacology, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India
| | - Archu Singh
- Department of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India
| | - Abdallah Mohammad Ibrahim
- Fundamentals of Nursing Department, College of Nursing, Imam Abdul Rahman Bin Faisal University, Dammam, Saudi Arabia
| | - Noora Alhajri
- Department of Epidemiology and Population Health, College of Medicine and Health Science, Khalifa University, Abu Dhabi, UAE
| | | | - Faheem Hyder Pottoo
- Department of Pharmacology, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, Damman, Saudi Arabia
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26
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TREM2, microglia, and Alzheimer's disease. Mech Ageing Dev 2021; 195:111438. [PMID: 33516818 DOI: 10.1016/j.mad.2021.111438] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/02/2021] [Accepted: 01/17/2021] [Indexed: 12/19/2022]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) has been suggested to play a crucial role in Alzheimer's disease (AD) pathogenesis, as revealed by genome-wide association studies (GWAS). Since then, rapidly increasing literature related to TREM2 has focused on elucidating its role in AD pathology. In this review, we summarize our understanding of TREM2 biology, explore TREM2 functions in microglia, address the multiple mechanisms of TREM2 in AD, and raise key questions for further investigations to elucidate the detailed roles and molecular mechanisms of TREM2 in microglial responses. A major breakthrough in our understanding of TREM2 is based on our hypothesis suggesting that TREM2 may act as a multifaceted player in microglial functions in AD brain homeostasis. We conclude that TREM2 can not only influence microglial functions in amyloid and tau pathologies but also participate in inflammatory responses and metabolism, acting alone or with other molecules, such as apolipoprotein E (APOE). This review provides novel insight into the broad role of TREM2 in microglial function in AD and enables us to develop new strategies aimed at the immune system to treat AD pathogenesis.
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27
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Hall-Roberts H, Agarwal D, Obst J, Smith TB, Monzón-Sandoval J, Di Daniel E, Webber C, James WS, Mead E, Davis JB, Cowley SA. TREM2 Alzheimer's variant R47H causes similar transcriptional dysregulation to knockout, yet only subtle functional phenotypes in human iPSC-derived macrophages. Alzheimers Res Ther 2020; 12:151. [PMID: 33198789 PMCID: PMC7667762 DOI: 10.1186/s13195-020-00709-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 10/20/2020] [Indexed: 01/21/2023]
Abstract
BACKGROUND TREM2 is a microglial cell surface receptor, with risk mutations linked to Alzheimer's disease (AD), including R47H. TREM2 signalling via SYK aids phagocytosis, chemotaxis, survival, and changes to microglial activation state. In AD mouse models, knockout (KO) of TREM2 impairs microglial clustering around amyloid and prevents microglial activation. The R47H mutation is proposed to reduce TREM2 ligand binding. We investigated cell phenotypes of the R47H mutant and TREM2 KO in a model of human microglia, and compared their transcriptional signatures, to determine the mechanism by which R47H TREM2 disrupts function. METHODS We generated human microglia-like iPSC-macrophages (pMac) from isogenic induced pluripotent stem cell (iPSC) lines, with homozygous R47H mutation or TREM2 knockout (KO). We firstly validated the effect of the R47H mutant on TREM2 surface and subcellular localization in pMac. To assess microglial phenotypic function, we measured phagocytosis of dead neurons, cell morphology, directed migration, survival, and LPS-induced inflammation. We performed bulk RNA-seq, comparing significant differentially expressed genes (DEGs; p < 0.05) between the R47H and KO versus WT, and bioinformatically predicted potential upstream regulators of TREM2-mediated gene expression. RESULTS R47H modified surface expression and shedding of TREM2, but did not impair TREM2-mediated signalling, or gross phenotypes that were dysregulated in the TREM2 KO (phagocytosis, motility, survival). However, altered gene expression in the R47H TREM2 pMac overlapped by 90% with the TREM2 KO and was characterised by dysregulation of genes involved with immunity, proliferation, activation, chemotaxis, and adhesion. Downregulated mediators of ECM adhesion included the vitronectin receptor αVβ3, and consequently, R47H TREM2 pMac adhered weakly to vitronectin compared with WT pMac. To counteract these transcriptional defects, we investigated TGFβ1, as a candidate upstream regulator. TGFβ1 failed to rescue vitronectin adhesion of pMac, although it improved αVβ3 expression. CONCLUSIONS The R47H mutation is not sufficient to cause gross phenotypic defects of human pMac under standard culture conditions. However, overlapping transcriptional defects with TREM2 KO supports the hypothesised partial loss-of-function effects of the R47H mutation. Furthermore, transcriptomics can guide us to more subtle phenotypic defects in the R47H cells, such as reduced cell adhesion, and can be used to predict targets for therapeutic intervention.
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Affiliation(s)
- Hazel Hall-Roberts
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE UK
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Devika Agarwal
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS UK
| | - Juliane Obst
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Thomas B. Smith
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | | | - Elena Di Daniel
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Caleb Webber
- UK Dementia Research Institute, Cardiff University, Cardiff, CF24 4HQ UK
| | - William S. James
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE UK
| | - Emma Mead
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - John B. Davis
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Sally A. Cowley
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE UK
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Ruganzu JB, Zheng Q, Wu X, He Y, Peng X, Jin H, Zhou J, Ma R, Ji S, Ma Y, Qian Y, Wang Y, Yang W. TREM2 overexpression rescues cognitive deficits in APP/PS1 transgenic mice by reducing neuroinflammation via the JAK/STAT/SOCS signaling pathway. Exp Neurol 2020; 336:113506. [PMID: 33065077 DOI: 10.1016/j.expneurol.2020.113506] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 02/08/2023]
Abstract
Overactivated microglia and neuroinflammation are considered to play a crucial role in the progression of Alzheimer's disease (AD). Triggering receptor expressed on myeloid cells-2 (TREM2), a type I transmembrane receptor, expressed uniquely by microglia in the brain, is involved in the neuroinflammatory responses of AD. In this study, to further explore the precise effects of TREM2 on neuroinflammation and the underlying mechanisms in AD, we employed a lentiviral-mediated strategy to overexpress TREM2 in the brain of APPswe/PS1dE9 (APP/PS1) transgenic mice and cultured BV2 cells. Our results showed that TREM2 overexpression rescued cognitive deficits, decreased β-amyloid (Aβ) plaques deposition, reduced synaptic and neuronal loss, as well as ameliorated neuroinflammation. The mechanistic study revealed that these protective effects were likely attributed to inhibition of neuroinflammatory responses through the JAK/STAT/SOCS signaling pathway and subsequent attenuation of pro-inflammatory cytokines. Furthermore, suppression of neuroinflammation might be ascribed to activation of the M2 microglia, as the levels of M2 phenotype markers Arg-1, IL-10 and Ym1 were markedly increased. Similarly, overexpression of TREM2 in BV2 cells also promoted M2 polarization and led to the alleviation of M1 microglial inflammatory responses through JAK/STAT/SOCS signaling pathway, suggesting that TREM2 is an important factor in shifting the microglia from M1 to M2 phenotype. Taken together, our results further provide insights into the role of TREM2 in AD pathogenesis and highlight TREM2 as a potential target against AD.
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Affiliation(s)
- John Bosco Ruganzu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Quzhao Zheng
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Medical Undergraduates of Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Xiangyuan Wu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Medical Undergraduates of Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Yingying He
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Xiaoqian Peng
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Hui Jin
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Jinsong Zhou
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Ruiyang Ma
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Medical Undergraduates of Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Shengfeng Ji
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Yanbing Ma
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Yihua Qian
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Yang Wang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Medical Undergraduates of Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Weina Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China; Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China.
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Yang J, Fu Z, Zhang X, Xiong M, Meng L, Zhang Z. TREM2 ectodomain and its soluble form in Alzheimer's disease. J Neuroinflammation 2020; 17:204. [PMID: 32635934 PMCID: PMC7341574 DOI: 10.1186/s12974-020-01878-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 06/23/2020] [Indexed: 12/14/2022] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a receptor mainly expressed on the surface of microglia. It mediates multiple pathophysiological processes in various diseases. Recently, TREM2 has been found to play a role in the development of Alzheimer's disease (AD). TREM2 is a transmembrane protein that is specifically expressed on microglia in the brain. It contains a long ectodomain that directly interacts with the extracellular environment to regulate microglial function. The ectodomain of TREM2 is processed by a disintegrin and metalloprotease, resulting in the release of a soluble form of TREM2 (sTREM2). Recent studies have demonstrated that sTREM2 is a bioactive molecule capable of binding ligands, activating microglia, and regulating immune responses during the AD continuum. Clinical studies revealed that sTREM2 level is elevated in cerebrospinal fluid (CSF) of AD patients, and the sTREM2 level is positively correlated with the levels of classical CSF biomarkers, namely t-tau and p-tau, indicating that it is a reliable predictor of the early stages of AD. Herein, we summarize the key results on the generation, structure, and function of sTREM2 to provide new insights into TREM2-related mechanisms underlying AD pathogenesis and to promote the development of TREM2-based therapeutic strategy.
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Affiliation(s)
- Jiaolong Yang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Zhihui Fu
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Xingyu Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Min Xiong
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Lanxia Meng
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
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Yuan C, Aierken A, Xie Z, Li N, Zhao J, Qing H. The age-related microglial transformation in Alzheimer's disease pathogenesis. Neurobiol Aging 2020; 92:82-91. [PMID: 32408056 DOI: 10.1016/j.neurobiolaging.2020.03.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/11/2020] [Accepted: 03/31/2020] [Indexed: 12/15/2022]
Abstract
Neuroinflammatory responses mediated by microglia, the resident immune cells of the central nervous system, have long been a subject of study in the field of Alzheimer's disease (AD). Microglia express a wide range of receptors that act as molecular sensors, through which they can fulfill their various functions. In this review, we first analyzed the changes in the expression levels of microglial membrane receptors SR-A, TREM2, CD36, CD33, and CR3 in aging and AD and described the different roles of these receptors in amyloid-beta clearance and inflammatory responses. Two classical hallmarks of AD are extracellular amyloid-beta deposits and intracellular aggregated phosphorylated tau. In AD, microglia reaction was initially thought to be triggered by amyloid deposits. New evidence showed it also associated with increased phosphorylation of tau. However, which first appeared and induced activated microglia is not clear. Then we summarized diverse opinions on it. Besides, as AD is tightly linked to aging, and microglia changes dramatically on aging, yet the relative impacts of both aging and microglia are less frequently considered, so at last, we discussed the roles of aging microglia in AD. We hope to provide a reference for subsequent research.
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Affiliation(s)
- Chunxu Yuan
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biological Sciences, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Ailikemu Aierken
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biological Sciences, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Zhen Xie
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biological Sciences, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Nuomin Li
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biological Sciences, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Juan Zhao
- School of Materials Science and Engineering, Department of Materials Processing Engineering, Beijing Institute of Technology, Beijing, China.
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biological Sciences, School of Life Science, Beijing Institute of Technology, Beijing, China.
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31
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Tambini MD, D'Adamio L. Trem2 Splicing and Expression are Preserved in a Human Aβ-producing, Rat Knock-in Model of Trem2-R47H Alzheimer's Risk Variant. Sci Rep 2020; 10:4122. [PMID: 32139718 PMCID: PMC7058057 DOI: 10.1038/s41598-020-60800-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/13/2020] [Indexed: 11/18/2022] Open
Abstract
The R47H variant of the Triggering-Receptor-Expressed on Myeloid cells 2 (TREM2) increases the risk of Alzheimer's disease (AD). Mutagenesis of exon 2 in Knock-in (KI) mouse models of the R47H variant introduced a cryptic splice site, leading to nonsense mediated decay. Since haploinsufficiency does not model Trem2-R47H function, a new rat KI model, the Trem2R47H KI rat was created. Human Aβ has higher propensity to form toxic Aβ species, which are considered the main pathogenic entity in AD, as compared to rodent Aβ, the rat Amyloid Precursor Protein (App) gene was mutated to produce human Aβ. Trem2 splicing and expression was measured in Trem2R47H KI rat brains and microglia by qualitative and quantitative RT-PCR. Trem2 levels and Trem2 processing was assessed by Western analysis. APP metabolite levels were determined by enzyme-linked immunosorbent assay (ELISA), for Human Aβ and soluble APP, and Western analysis, for full length APP, βCTF and αCTF. Trem2 expression and Trem2 levels are unchanged in Trem2R47H KI rats. The artifactual splicing seen in KI mouse models is not present; additionally, two novel isoforms of rat Trem2 are described. Trem2R47H rat brains have lower human Aβ38, sAPPα and sAPPβ levels. Thus, Trem2R47H KI rats may prove valuable to define pathogenic mechanisms triggered by the Trem2 R47H variant, including those mediated by toxic species of human Aβ peptides.
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Affiliation(s)
- Marc D Tambini
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA.
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32
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Sánchez-Ruiz de Gordoa J, Erro ME, Vicuña-Urriza J, Zelaya MV, Tellechea P, Acha B, Zueco S, Urdánoz-Casado A, Roldán M, Blanco-Luquin I, Mendioroz M. Microglia-Related Gene Triggering Receptor Expressed in Myeloid Cells 2 (TREM2) Is Upregulated in the Substantia Nigra of Progressive Supranuclear Palsy. Mov Disord 2020; 35:885-890. [PMID: 32031293 DOI: 10.1002/mds.27992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/22/2020] [Accepted: 01/23/2020] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The role of the microglia-related gene triggering receptor expressed in myeloid cells 2 (TREM2) in primary tauopathies, such as progressive supranuclear palsy (PSP), still remains unclear. OBJECTIVES The objective of this study was to profile overall and transcript-specific TREM2 expression levels in the substantia nigra (SN) of PSP patients and controls. METHODS SN samples from neuropathologically confirmed PSP cases (n = 24) and controls (n = 14) were used to measure TREM2 and TREM2-modulating gene Membrane-spanning 4-domains subfamily A member 4A (MS4A4A) mRNA levels by real-time quantitative polymerase chain reaction. Correlation with hyperphosphorylated tau protein burden was assessed. RESULTS Overall TREM2 and each of the 3 TREM2 transcripts mRNA levels were significantly increased in the SN of PSP cases versus controls. TREM2 mRNA levels positively correlated with hyperphosphorylated tau burden in SN, specifically in neurons. The MS4A4A gene was also upregulated in PSP patients versus controls. CONCLUSIONS These results add evidence to the involvement of microglia in the disease process of PSP. These findings support the idea that different tauopathies may share common patterns of deregulation in innate immune molecular pathways. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Javier Sánchez-Ruiz de Gordoa
- Department of Neurology, Complejo Hospitalario de Navarra, Pamplona, Navarra, Spain.,Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - María Elena Erro
- Department of Neurology, Complejo Hospitalario de Navarra, Pamplona, Navarra, Spain.,Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - Janire Vicuña-Urriza
- Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | | | - Paula Tellechea
- Department of Neurology, Complejo Hospitalario de Navarra, Pamplona, Navarra, Spain
| | - Blanca Acha
- Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - Sara Zueco
- Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - Amaya Urdánoz-Casado
- Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - Miren Roldán
- Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - Idoia Blanco-Luquin
- Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
| | - Maite Mendioroz
- Department of Neurology, Complejo Hospitalario de Navarra, Pamplona, Navarra, Spain.,Neuroepigenetics Laboratory-Navarrabiomed, Universidad Pública de Navarra, Navarra Institute for Health Research, Pamplona, Navarra, Spain
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Singh AK, Mishra G, Maurya A, Awasthi R, Kumari K, Thakur A, Rai A, Rai GK, Sharma B, Kulkarni GT, Singh SK. Role of TREM2 in Alzheimer's Disease and its Consequences on β- Amyloid, Tau and Neurofibrillary Tangles. Curr Alzheimer Res 2020; 16:1216-1229. [DOI: 10.2174/1567205016666190903102822] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/21/2019] [Accepted: 08/21/2019] [Indexed: 11/22/2022]
Abstract
:
Alzheimer's Disease (AD) is age-related neurodegenerative disorder recognized by a steadily
gradual cognitive decline that has devastating personal and socioeconomic implications. Recently, some
genetic factors for AD have been identified which attracted wide attention of researchers in different
areas of AD biology and possible new therapeutic targets. Alternative forms of triggering receptor expressed
on myeloid cells 2 (TREM2) genes are examples of such risk factors, which contribute higher
risk for developing AD. Comprehending TREM2 function pledge to provide salient insight into how
neuroinflammation contributes to AD pathology. The dearth of microglial TREM2 shepherd to augmented
tau pathology is couple with frequent enhancement of activated neuronal stress kinases. The involvement
of TREM2 in the regulation of tau-associated innate immune response of the CNS has clearly
demonstrated through these findings. However, whether decrease level of TREM2 assists pathology of
tau through changed clearance and pathological escalation of tau or through direct contact between microglia
and neuron and any alternative possible mechanisms need to examine. This review briefly summarizes
distinct functional roles of TREM2 in AD pathology and highlights the TREM2 gene regulation.
We have also addressed the impact of TREM2 on β-amyloid plaques and tau pathology in Alzheimer’s
disease.
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Affiliation(s)
- Anurag K. Singh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India
| | - Gaurav Mishra
- Department of Pharmacy, School of Chemical Sciences & Pharmacy, Central University of Rajasthan, Bandar Sindri, Kishangarh, Ajmer-305817, Rajasthan, India
| | - Anand Maurya
- Department of Pharmacy, School of Chemical Sciences & Pharmacy, Central University of Rajasthan, Bandar Sindri, Kishangarh, Ajmer-305817, Rajasthan, India
| | - Rajendra Awasthi
- Department of Pharmaceutics, Amity Institute of Pharmacy, Amity University Uttar Pradesh, Sector 125, Noida - 201303, India
| | - Komal Kumari
- Department of Pharmacy, School of Chemical Sciences & Pharmacy, Central University of Rajasthan, Bandar Sindri, Kishangarh, Ajmer-305817, Rajasthan, India
| | - Abhimanyu Thakur
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong SAR, China
| | - Arati Rai
- Hygia Institute of Pharmaceutical Education & Research, Lucknow-226020, Uttar Pradesh, India
| | - Gopal Kumar Rai
- Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi- 221005, Uttar Pradesh, India
| | - Bhupesh Sharma
- Department of Pharmacology, Amity Institute of Pharmacy, Amity University Uttar Pradesh, Sector 125, Noida - 201303, India
| | - Giriraj T Kulkarni
- Department of Pharmaceutics, Amity Institute of Pharmacy, Amity University Uttar Pradesh, Sector 125, Noida - 201303, India
| | - Santosh Kumar Singh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India
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Karanfilian L, Tosto MG, Malki K. The role of TREM2 in Alzheimer's disease; evidence from transgenic mouse models. Neurobiol Aging 2019; 86:39-53. [PMID: 31727362 DOI: 10.1016/j.neurobiolaging.2019.09.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is a currently incurable neurodegenerative disorder. Several genetic studies have identified a rare variant of triggering receptor expressed on myeloid cells 2 (TREM2) as a risk factor for AD. TREM2 is thought to trigger the microglial response to amyloid plaques. Mouse models have helped elucidate mechanisms through which TREM2 affects microglial function and modulates pathological features of AD. A synthesis of the 35 mouse-model studies included in this review indicates that TREM2 modulates amyloid plaque composition and deposition, microglial morphology and proliferation, neuroinflammation, and tau phosphorylation. TREM2 also acts as a sensor for anionic lipids exposed during neuronal apoptosis and Aβ deposition, may improve spatial abilities and memory, and protect against apoptosis. In early stages of AD, TREM2 knock-down reduces expression of proinflammatory cytokines and upregulates anti-inflammatory cytokines but in later stages, TREM2 may contribute to the disease by aggravating neuroinflammation. The results provide insight into TREM2-related mechanisms that may be associated with AD in humans and may aid future development of disease-modifying pharmacological treatments targeting TREM2.
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Affiliation(s)
- Lucine Karanfilian
- King's College London at the Institute of Psychiatry, Psychology and Neuroscience (IOPPN), London, UK
| | - Maria Grazia Tosto
- King's College London at the Institute of Psychiatry, Psychology and Neuroscience (IOPPN), London, UK
| | - Karim Malki
- King's College London at the Institute of Psychiatry, Psychology and Neuroscience (IOPPN), London, UK; UCB Pharma, Statistical Sciences and Innovation, Slough, UK.
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35
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Zhao Y, Wu X, Li X, Jiang LL, Gui X, Liu Y, Sun Y, Zhu B, Piña-Crespo JC, Zhang M, Zhang N, Chen X, Bu G, An Z, Huang TY, Xu H. TREM2 Is a Receptor for β-Amyloid that Mediates Microglial Function. Neuron 2019. [PMID: 29518356 DOI: 10.1016/j.neuron.2018.01.031] [Citation(s) in RCA: 421] [Impact Index Per Article: 84.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Mutations in triggering receptor expressed on myeloid cells 2 (TREM2) have been linked to increased Alzheimer's disease (AD) risk. Neurobiological functions of TREM2 and its pathophysiological ligands remain elusive. Here we found that TREM2 directly binds to β-amyloid (Aβ) oligomers with nanomolar affinity, whereas AD-associated TREM2 mutations reduce Aβ binding. TREM2 deficiency impairs Aβ degradation in primary microglial culture and mouse brain. Aβ-induced microglial depolarization, K+ inward current induction, cytokine expression and secretion, migration, proliferation, apoptosis, and morphological changes are dependent on TREM2. In addition, TREM2 interaction with its signaling adaptor DAP12 is enhanced by Aβ, regulating downstream phosphorylation of SYK and GSK3β. Our data demonstrate TREM2 as a microglial Aβ receptor transducing physiological and AD-related pathological effects associated with Aβ.
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Affiliation(s)
- Yingjun Zhao
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Xilin Wu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA; Department of Neurology, Union Hospital, and Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, Fujian 350001, China
| | - Xiaoguang Li
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Lu-Lin Jiang
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Xun Gui
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yan Liu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA; Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Yu Sun
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Bing Zhu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Juan C Piña-Crespo
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Muxian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Ningyan Zhang
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Xiaochun Chen
- Department of Neurology, Union Hospital, and Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, Fujian 350001, China
| | - Guojun Bu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China; Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Zhiqiang An
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Timothy Y Huang
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Huaxi Xu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA; Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
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Sheng L, Chen M, Cai K, Song Y, Yu D, Zhang H, Xu G. Microglial Trem2 induces synaptic impairment at early stage and prevents amyloidosis at late stage in APP/PS1 mice. FASEB J 2019; 33:10425-10442. [PMID: 31219699 DOI: 10.1096/fj.201900527r] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Triggering receptor expressed in myeloid cells (TREM)2 is a genetic high-risk factor for sporadic Alzheimer's disease (AD) and is considered a potential target for AD diagnosis and therapy, although its role in the different stages of AD remains controversial. We generated an embryonic deletion of Trem2 (whole body deletion) and induced hippocampal- and cortical-specific knockdown of microglial Trem2 at different stages of the AD process in amyloid precursor protein/Psen1 mice by adeno-associated virus (AAV) infection. AAV infection induced microglial Trem2 overexpression in the hippocampus of wild-type (WT) and thymus cell antigen 1-enhanced green fluorescent protein mice. Mice were subjected to ethological and pathologic tests. Whole body genetic deletion of Trem2 exerted different electrophysiological outcomes between different AD pathologic stages, which results from a complex integration of synaptic loss and amyloid aggregation. Interestingly, knockdown of Trem2 at the early-middle stage of AD (2-6 mo) prevents synaptic loss through directly inhibiting microglial phagocytosis, whereas knockdown of Trem2 at the middle-late stage of AD (6-10 mo) accelerates synaptic dysfunction because of more severe amyloid deposition caused by the depression of microglial phagocytosis. Additionally, hippocampal overexpression of Trem2 in WT mice results in significant synaptic impairment. Here, with transgenic technology and electrophysiological assay, we revealed that TREM2 up-regulation promotes microglial phagocytosis equally against synapse and amyloid plaques and eventually results in different outcomes. During the early-middle pathologic stage, TREM2 enhancing microglial phagocytosis mainly causes synaptic loss. However, TREM2 up-regulating microglial phagocytosis gradually supports a positive role when amyloid deposition occupies the leading position at the middle-late pathologic stage. In this study, we highlighted that TREM2 triggers synaptic loss during AD pathology development.-Sheng, L., Chen, M., Cai, K., Song, Y., Yu, D., Zhang, H., Xu, G. Microglial Trem2 induces synaptic impairment at early stage and prevents amyloidosis at late stage in APP/PS1 mice.
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Affiliation(s)
- Liang Sheng
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Mingming Chen
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Keshu Cai
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yu Song
- Pharmacy College, Xinxiang Medical University, Xinxiang, China
| | - Dongsheng Yu
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Hui Zhang
- Pharmacy College, Xinxiang Medical University, Xinxiang, China
| | - Guangxu Xu
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
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37
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Del-Aguila JL, Benitez BA, Li Z, Dube U, Mihindukulasuriya KA, Budde JP, Farias FHG, Fernández MV, Ibanez L, Jiang S, Perrin RJ, Cairns NJ, Morris JC, Harari O, Cruchaga C. TREM2 brain transcript-specific studies in AD and TREM2 mutation carriers. Mol Neurodegener 2019; 14:18. [PMID: 31068200 PMCID: PMC6505298 DOI: 10.1186/s13024-019-0319-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 04/26/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Low frequency coding variants in TREM2 are associated with Alzheimer disease (AD) risk and cerebrospinal fluid (CSF) TREM2 protein levels are different between AD cases and controls. Similarly, TREM2 risk variant carriers also exhibit differential CSF TREM2 levels. TREM2 has three different alternative transcripts, but most of the functional studies only model the longest transcript. No studies have analyzed TREM2 expression levels or alternative splicing in brains from AD and cognitively normal individuals. We wanted to determine whether there was differential expression of TREM2 in sporadic-AD cases versus AD-TREM2 carriers vs sex- and aged-matched normal controls; and if this differential expression was due to a particular TREM2 transcript. METHODS We analyzed RNA-Seq data from parietal lobe brain tissue from AD cases with TREM2 variants (n = 33), AD cases (n = 195) and healthy controls (n = 118), from three independent datasets using Kallisto and the R package tximport to determine the read count for each transcript and quantified transcript abundance as transcripts per million. RESULTS The three TREM2 transcripts were expressed in brain cortex in the three datasets. We demonstrate for the first time that the transcript that lacks the transmembrane domain and encodes a soluble form of TREM2 (sTREM2) has an expression level around 60% of the canonical transcript, suggesting that around 25% of the sTREM2 protein levels could be explained by this transcript. We did not observe a difference in the overall TREM2 expression level between cases and controls. However, the isoform which lacks the 5' exon, but includes the transmembrane domain, was significantly lower in TREM2- p.R62H carriers than in AD cases (p = 0.007). CONCLUSION Using bulk RNA-Seq data from three different cohorts, we were able to quantify the expression level of the three TREM2 transcripts, demonstrating: (1) all three transcripts of them are highly expressed in the human cortex, (2) that up to 25% of the sTREM2 may be due to the expression of a specific isoform and not TREM2 cleavage; and (3) that TREM2 risk variants do not affect expression levels, suggesting that the effect of the TREM2 variants on CSF levels occurs at post-transcriptional level.
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Affiliation(s)
- Jorge L. Del-Aguila
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Bruno A. Benitez
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Zeran Li
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Umber Dube
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Kathie A. Mihindukulasuriya
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
| | - John P. Budde
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Fabiana H. G. Farias
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Maria Victoria Fernández
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Laura Ibanez
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Shan Jiang
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
| | - Richard J. Perrin
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO USA
| | - Nigel J. Cairns
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO USA
| | - John C. Morris
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO USA
| | - Oscar Harari
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
| | - Carlos Cruchaga
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
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Wang S, Colonna M. Microglia in Alzheimer's disease: A target for immunotherapy. J Leukoc Biol 2019; 106:219-227. [PMID: 30725482 DOI: 10.1002/jlb.mr0818-319r] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/11/2018] [Accepted: 01/14/2019] [Indexed: 12/29/2022] Open
Abstract
Microglia are resident Mϕs of the CNS that play pleiotropic functions in brain development and homeostasis. Impaired microglial functions are thought to be involved in the onset and progression of various neurodevelopmental and neurodegenerative diseases. Thus, understanding microglia in these settings may indicate new approaches for therapeutic intervention. Here, we review recent evidence implicating microglia in Alzheimer's disease and discuss potential therapeutic strategies targeting microglia and their receptors in this disease.
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Affiliation(s)
- Shoutang Wang
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Marco Colonna
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri, USA
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Gratuze M, Leyns CEG, Holtzman DM. New insights into the role of TREM2 in Alzheimer's disease. Mol Neurodegener 2018; 13:66. [PMID: 30572908 PMCID: PMC6302500 DOI: 10.1186/s13024-018-0298-9] [Citation(s) in RCA: 277] [Impact Index Per Article: 46.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 11/28/2018] [Indexed: 12/22/2022] Open
Abstract
Alzheimer's disease (AD) is the leading cause of dementia. The two histopathological markers of AD are amyloid plaques composed of the amyloid-β (Aβ) peptide, and neurofibrillary tangles of aggregated, abnormally hyperphosphorylated tau protein. The majority of AD cases are late-onset, after the age of 65, where a clear cause is still unknown. However, there are likely different multifactorial contributors including age, enviornment, biology and genetics which can increase risk for the disease. Genetic predisposition is considerable, with heritability estimates of 60-80%. Genetic factors such as rare variants of TREM2 (triggering receptor expressed on myeloid cells-2) strongly increase the risk of developing AD, confirming the role of microglia in AD pathogenesis. In the last 5 years, several studies have dissected the mechanisms by which TREM2, as well as its rare variants affect amyloid and tau pathologies and their consequences in both animal models and in human studies. In this review, we summarize increases in our understanding of the involvement of TREM2 and microglia in AD development that may open new therapeutic strategies targeting the immune system to influence AD pathogenesis.
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Affiliation(s)
- Maud Gratuze
- Department of Neurology, St. Louis, USA
- Hope Center for Neurological Disorders, St. Louis, USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Cheryl E. G. Leyns
- Department of Neurology, St. Louis, USA
- Hope Center for Neurological Disorders, St. Louis, USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - David M. Holtzman
- Department of Neurology, St. Louis, USA
- Hope Center for Neurological Disorders, St. Louis, USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110 USA
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Fields JA, Spencer B, Swinton M, Qvale EM, Marquine MJ, Alexeeva A, Gough S, Soontornniyomkij B, Valera E, Masliah E, Achim CL, Desplats P. Alterations in brain TREM2 and Amyloid-β levels are associated with neurocognitive impairment in HIV-infected persons on antiretroviral therapy. J Neurochem 2018; 147:784-802. [PMID: 30152135 PMCID: PMC6310632 DOI: 10.1111/jnc.14582] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/27/2022]
Abstract
Neuroinflammation is a common pathological correlate of HIV-associated neurocognitive disorders (HAND) in individuals on antiretroviral therapy (ART). Triggering receptor expressed on myeloid cells 2 (TREM2) regulates neuroinflammation, clears extracellular Amyloid (A)-β, surveys for damaged neurons, and orchestrates microglial differentiation. TREM2 has not been studied in HIV+ brain tissues. In this retrospective study, we investigated TREM2 expression levels and localization to microglia, Aβ protein levels, and tumor necrosis factor (TNF)-α transcript levels in the frontal cortices of 52 HIV+ decedents. All donors had been on ART; 14 were cognitively normal (CN), 17 had an asymptomatic neurocognitive impairment (ANI), and 21 had a minor neurocognitive disorder (MND). Total TREM2 protein levels were increased in the soluble and decreased in the membrane-enriched fractions of MND brain tissues compared to CN; however, brains from MND Hispanics showed the most robust alterations in TREM2 as well as significantly increased TNF-α mRNA and Aβ levels when compared to CN Hispanics. Significant alterations in the expression of total TREM2 protein and transcripts for TNF-α were not observed in non-Hispanics, despite higher levels of Aβ in the non-Hispanic CN group compared to the non-Hispanic MND groups. These findings show that decreased and increased TREM2 in membrane-bound fractions and in soluble-enriched fractions, respectively, is associated with increased Aβ and neuroinflammation in this cohort of HIV+ brains, particularly those identifying as Hispanics. These findings suggest a role for TREM2 in the brain of HIV+ individuals may deserve more investigation as a biomarker for HAND and as a possible therapeutic target. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
- Jerel Adam Fields
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Brian Spencer
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Mary Swinton
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Emma Martine Qvale
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - María J. Marquine
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Arina Alexeeva
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Sarah Gough
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Benchawanna Soontornniyomkij
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Elvira Valera
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Eliezer Masliah
- Department of Pathology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Cristian L. Achim
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
- Department of Pathology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
| | - Paula Desplats
- Department of Pathology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA, 92093, United States of America
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The role of TREM2 in Alzheimer's disease and other neurodegenerative disorders. Lancet Neurol 2018; 17:721-730. [PMID: 30033062 DOI: 10.1016/s1474-4422(18)30232-1] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease is a genetically complex disorder; rare variants in the triggering receptor expressed on myeloid cells 2 (TREM2) gene have been shown to as much as triple an individual's risk of developing Alzheimer's disease. TREM2 is a transmembrane receptor expressed in cells of the myeloid lineage, and its association with Alzheimer's disease supports the involvement of immune and inflammatory pathways in the cause of the disease, rather than as a consequence of the disease. TREM2 variants associated with Alzheimer's disease induce partial loss of function of the TREM2 protein and alter the behaviour of microglial cells, including their response to amyloid plaques. TREM2 variants have also been shown to cause polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy and frontotemporal dementia. Although the low frequency of TREM2 variants makes it difficult to establish robust genotype-phenotype correlations, such studies are essential to enable a comprehensive understanding of the role of TREM2 in different neurological diseases, with the ultimate goal of developing novel therapeutic approaches.
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Deming Y, Li Z, Benitez BA, Cruchaga C. Triggering receptor expressed on myeloid cells 2 (TREM2): a potential therapeutic target for Alzheimer disease? Expert Opin Ther Targets 2018; 22:587-598. [PMID: 29889572 DOI: 10.1080/14728222.2018.1486823] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
INTRODUCTION There are currently no effective therapeutics for Alzheimer disease (AD). Clinical trials targeting amyloid beta thus far have shown very little benefit and only in the earliest stages of disease. These limitations have driven research to identify alternative therapeutic targets, one of the most promising is the triggering receptor expressed on myeloid cells 2 (TREM2). Areas covered: Here, we review the literature to-date and discuss the potentials and pitfalls for targeting TREM2 as a potential therapeutic for AD. We focus on research in animal and cell models for AD and central nervous system injury models which may help in understanding the role of TREM2 in disease. Expert opinion: Studies suggest TREM2 plays a key role in AD pathology; however, results have been conflicting about whether TREM2 is beneficial or harmful. More research is necessary before designing TREM2-targeting therapies. Successful therapeutics will most likely be administered early in disease.
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Affiliation(s)
- Yuetiva Deming
- a Department of Psychiatry , Washington University School of Medicine , St Louis , MO , USA
| | - Zeran Li
- a Department of Psychiatry , Washington University School of Medicine , St Louis , MO , USA
| | - Bruno A Benitez
- b Department of Medicine , Washington University School of Medicine , St Louis , MO , USA
| | - Carlos Cruchaga
- a Department of Psychiatry , Washington University School of Medicine , St Louis , MO , USA.,c Department of Developmental Biology , Washington University School of Medicine , St Louis , MO , USA.,d Knight Alzheimer's Disease Research Center , Washington University School of Medicine , St Louis , MO , USA.,e Hope Center for Neurological Disorders , Washington University School of Medicine , St Louis , MO , USA
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43
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Chunchai T, Chattipakorn N, Chattipakorn SC. The possible factors affecting microglial activation in cases of obesity with cognitive dysfunction. Metab Brain Dis 2018; 33:615-635. [PMID: 29164373 DOI: 10.1007/s11011-017-0151-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 11/14/2017] [Indexed: 02/07/2023]
Abstract
Obesity has reached epidemic proportions in many countries around the world. Several studies have reported that obesity can lead to the development of cognitive decline. There is increasing evidence to demonstrate that microglia play a crucial role in cognitive decline in cases of obesity, Alzheimer's disease and also in the aging process. Although there have been several studies into microglia over the past decades, the mechanistic link between microglia and cognitive decline in obese models is still not fully understood. In this review, the current available evidence from both in vitro and in vivo investigations regarding the association between the alteration in microglial activity in different obese models with respect to cognition are included. The metabolite profiles from obesity, adiposity, dietary and hormone affected microglial activation and its function in the brain are comprehensively summarized. In addition, the possible roles of microglial activation in relation to cognitive dysfunction are also presented and discussed. To ensure a balanced perspective controversial reports regarding these issues are included and discussed.
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Affiliation(s)
- Titikorn Chunchai
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
- Cardiac Electrophysiology Research and Training Center, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
- Cardiac Electrophysiology Research and Training Center, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Siriporn C Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
- Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, 50200, Thailand.
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44
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Cheng-Hathaway PJ, Reed-Geaghan EG, Jay TR, Casali BT, Bemiller SM, Puntambekar SS, von Saucken VE, Williams RY, Karlo JC, Moutinho M, Xu G, Ransohoff RM, Lamb BT, Landreth GE. The Trem2 R47H variant confers loss-of-function-like phenotypes in Alzheimer's disease. Mol Neurodegener 2018; 13:29. [PMID: 29859094 PMCID: PMC5984804 DOI: 10.1186/s13024-018-0262-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 05/23/2018] [Indexed: 12/20/2022] Open
Abstract
Background The R47H variant of Triggering Receptor Expressed on Myeloid cells 2 (TREM2) confers greatly increased risk for Alzheimer’s disease (AD), reflective of a central role for myeloid cells in neurodegeneration. Understanding how this variant confers AD risk promises to provide important insights into how myeloid cells contribute to AD pathogenesis and progression. Methods In order to investigate this mechanism, CRISPR/Cas9 was used to generate a mouse model of AD harboring one copy of the single nucleotide polymorphism (SNP) encoding the R47H variant in murine Trem2. TREM2 expression, myeloid cell responses to amyloid deposition, plaque burden, and neuritic dystrophy were assessed at 4 months of age. Results AD mice heterozygous for the Trem2 R47H allele exhibited reduced total Trem2 mRNA expression, reduced TREM2 expression around plaques, and reduced association of myeloid cells with plaques. These results were comparable to AD mice lacking one copy of Trem2. AD mice heterozygous for the Trem2 R47H allele also showed reduced myeloid cell responses to amyloid deposition, including a reduction in proliferation and a reduction in CD45 expression around plaques. Expression of the Trem2 R47H variant also reduced dense core plaque number but increased plaque-associated neuritic dystrophy. Conclusions These data suggest that the AD-associated TREM2 R47H variant increases risk for AD by conferring a loss of TREM2 function and enhancing neuritic dystrophy around plaques. Electronic supplementary material The online version of this article (10.1186/s13024-018-0262-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Paul J Cheng-Hathaway
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA.,Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Erin G Reed-Geaghan
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA
| | - Taylor R Jay
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA
| | - Brad T Casali
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA.,Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Shane M Bemiller
- Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Department of Medical and Molecular Genetics, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Shweta S Puntambekar
- Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Department of Medical and Molecular Genetics, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Victoria E von Saucken
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Roxanne Y Williams
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - J Colleen Karlo
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA
| | - Miguel Moutinho
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Guixiang Xu
- Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Department of Medical and Molecular Genetics, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA
| | - Richard M Ransohoff
- Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA.,Third Rock Ventures, Boston, MA, 02116, USA
| | - Bruce T Lamb
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA.,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Department of Medical and Molecular Genetics, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.,Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA
| | - Gary E Landreth
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, 44106, USA. .,Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA. .,Paul and Carole Stark Neurosciences Research Institute, Indiana University, School of Medicine, Indianapolis, IN, 46202, USA.
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Yanaizu M, Sakai K, Tosaki Y, Kino Y, Satoh JI. Small nuclear RNA-mediated modulation of splicing reveals a therapeutic strategy for a TREM2 mutation and its post-transcriptional regulation. Sci Rep 2018; 8:6937. [PMID: 29720600 PMCID: PMC5931963 DOI: 10.1038/s41598-018-25204-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/17/2018] [Indexed: 12/30/2022] Open
Abstract
Loss-of-function mutations in TREM2 cause Nasu-Hakola disease (NHD), a rare genetic disease characterized by early-onset dementia with leukoencephalopathy and bone cysts. An NHD-associated mutation, c.482 + 2 T > C, disrupts the splice donor site of intron 3 and causes aberrant skipping of exon 3, resulting in the loss of full-length TREM2 protein. Here, we examined the efficacy of artificial U1 and U7 small nuclear RNAs (snRNAs) designed to enhance exon 3 inclusion. Using mutant TREM2 minigenes, we found that some modified U1, but not U7, snRNAs enhanced exon 3 inclusion and restored TREM2 protein expression. Unexpectedly, we found that exon 3 of wild-type TREM2 is an alternative exon, whose skipping leads to reduced expression of the full-length protein. Indeed, TREM2 protein levels were modulated by modified snRNAs that either promoted or repressed exon 3 inclusion. The splice donor site flanking exon 3 was predicted to be weak, which may explain both the alternative splicing of exon 3 under normal conditions and complete exon skipping when the c.482 + 2 T > C mutation was present. Collectively, our snRNA-based approaches provide a potential therapeutic strategy for NHD-associated mis-splicing and novel insights into the post-transcriptional regulation of TREM2.
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Affiliation(s)
- Motoaki Yanaizu
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Kenji Sakai
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Youhei Tosaki
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Yoshihiro Kino
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan.
| | - Jun-Ichi Satoh
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
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Freudenberg-Hua Y, Li W, Davies P. The Role of Genetics in Advancing Precision Medicine for Alzheimer's Disease-A Narrative Review. Front Med (Lausanne) 2018; 5:108. [PMID: 29740579 PMCID: PMC5928202 DOI: 10.3389/fmed.2018.00108] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 04/03/2018] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is the most common type of dementia, which has a substantial genetic component. AD affects predominantly older people. Accordingly, the prevalence of dementia has been rising as the population ages. To date, there are no effective interventions that can cure or halt the progression of AD. The only available treatments are the management of certain symptoms and consequences of dementia. The current state-of-the-art medical care for AD comprises three simple principles: prevent the preventable, achieve early diagnosis, and manage the manageable symptoms. This review provides a summary of the current state of knowledge of risk factors for AD, biological diagnostic testing, and prospects for treatment. Special emphasis is given to recent advances in genetics of AD and the way genomic data may support prevention, early intervention, and development of effective pharmacological treatments. Mutations in the APP, PSEN1, and PSEN2 genes cause early onset Alzheimer's disease (EOAD) that follows a Mendelian inheritance pattern. For late onset Alzheimer's disease (LOAD), APOE4 was identified as a major risk allele more than two decades ago. Population-based genome-wide association studies of late onset AD have now additionally identified common variants at roughly 30 genetic loci. Furthermore, rare variants (allele frequency <1%) that influence the risk for LOAD have been identified in several genes. These genetic advances have broadened our insights into the biological underpinnings of AD. Moreover, the known genetic risk variants could be used to identify presymptomatic individuals at risk for AD and support diagnostic assessment of symptomatic subjects. Genetic knowledge may also facilitate precision medicine. The goal of precision medicine is to use biological knowledge and other health information to predict individual disease risk, understand disease etiology, identify disease subcategories, improve diagnosis, and provide personalized treatment strategies. We discuss the potential role of genetics in advancing precision medicine for AD along with its ethical challenges. We outline strategies to implement genomics into translational clinical research that will not only improve accuracy of dementia diagnosis, thus enabling more personalized treatment strategies, but may also speed up the discovery of novel drugs and interventions.
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Affiliation(s)
- Yun Freudenberg-Hua
- Litwin-Zucker Center for the study of Alzheimer’s Disease, The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States
- Division of Geriatric Psychiatry, Zucker Hillside Hospital, Northwell Health, Glen Oaks, NY, United States
| | - Wentian Li
- Robert S Boas Center for Genomics and Human Genetics, The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Peter Davies
- Litwin-Zucker Center for the study of Alzheimer’s Disease, The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States
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47
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Bekris LM, Khrestian M, Dyne E, Shao Y, Pillai JA, Rao SM, Bemiller SM, Lamb B, Fernandez HH, Leverenz JB. Soluble TREM2 and biomarkers of central and peripheral inflammation in neurodegenerative disease. J Neuroimmunol 2018; 319:19-27. [PMID: 29685286 DOI: 10.1016/j.jneuroim.2018.03.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 01/22/2023]
Abstract
Alzheimer's disease (AD) has been genetically and pathologically associated with neuroinflammation. Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial receptor involved in innate immunity. TREM2 rare protein coding genetic variants have been linked to AD. A soluble TREM2 (sTREM2) cleavage product is elevated in AD. It is unclear whether there is a relationship between elevated sTREM2 and markers of inflammation. The hypothesis of this investigation was that central and peripheral inflammation play a role in sTREM2 levels in AD. A consistent association of peripheral or central markers of inflammation and CSF sTREM2 levels was not found, suggesting a limited impact of general inflammation on sTREM2 levels. An association between peripheral sTREM2 levels and CSF sTREM2, as well as an association between CSF sTREM2 and a marker of blood brain barrier integrity, was observed in AD, suggesting a potential role of peripheral TREM2 in central TREM2 biology.
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Affiliation(s)
- L M Bekris
- Cleveland Clinic, Genomic Medicine Institute, Cleveland, OH, United States.
| | - M Khrestian
- Cleveland Clinic, Genomic Medicine Institute, Cleveland, OH, United States
| | - E Dyne
- Kent State University, Departoment of Biomedicine, Kent, OH, United States
| | - Y Shao
- Cleveland Clinic, Genomic Medicine Institute, Cleveland, OH, United States
| | - J A Pillai
- Cleveland Clinic, Lou Ruvo Center for Brain Health, Cleveland, OH, United States
| | - S M Rao
- Cleveland Clinic, Lou Ruvo Center for Brain Health, Cleveland, OH, United States
| | - S M Bemiller
- Indiana University, Department of Neuroscience, Indianapolis, IN, United States
| | - B Lamb
- Indiana University, Department of Neuroscience, Indianapolis, IN, United States
| | - H H Fernandez
- Cleveland Clinic, Center for Neurological Restoration, Cleveland, OH, United States
| | - J B Leverenz
- Cleveland Clinic, Lou Ruvo Center for Brain Health, Cleveland, OH, United States
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Frost GR, Li YM. The role of astrocytes in amyloid production and Alzheimer's disease. Open Biol 2017; 7:170228. [PMID: 29237809 PMCID: PMC5746550 DOI: 10.1098/rsob.170228] [Citation(s) in RCA: 241] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/16/2017] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease (AD) is marked by the presence of extracellular amyloid beta (Aβ) plaques, intracellular neurofibrillary tangles (NFTs) and gliosis, activated glial cells, in the brain. It is thought that Aβ plaques trigger NFT formation, neuronal cell death, neuroinflammation and gliosis and, ultimately, cognitive impairment. There are increased numbers of reactive astrocytes in AD, which surround amyloid plaques and secrete proinflammatory factors and can phagocytize and break down Aβ. It was thought that neuronal cells were the major source of Aβ. However, mounting evidence suggests that astrocytes may play an additional role in AD by secreting significant quantities of Aβ and contributing to overall amyloid burden in the brain. Astrocytes are the most numerous cell type in the brain, and therefore even minor quantities of amyloid secretion from individual astrocytes could prove to be substantial when taken across the whole brain. Reactive astrocytes have increased levels of the three necessary components for Aβ production: amyloid precursor protein, β-secretase (BACE1) and γ-secretase. The identification of environmental factors, such as neuroinflammation, that promote astrocytic Aβ production, could redefine how we think about developing therapeutics for AD.
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Affiliation(s)
- Georgia R Frost
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Programs of Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
| | - Yue-Ming Li
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Programs of Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
- Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
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Jay TR, von Saucken VE, Landreth GE. TREM2 in Neurodegenerative Diseases. Mol Neurodegener 2017; 12:56. [PMID: 28768545 PMCID: PMC5541421 DOI: 10.1186/s13024-017-0197-5] [Citation(s) in RCA: 256] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/20/2017] [Indexed: 12/12/2022] Open
Abstract
TREM2 variants have been identified as risk factors for Alzheimer's disease (AD) and other neurodegenerative diseases (NDDs). Because TREM2 encodes a receptor exclusively expressed on immune cells, identification of these variants conclusively demonstrates that the immune response can play an active role in the pathogenesis of NDDs. These TREM2 variants also confer the highest risk for developing Alzheimer's disease of any risk factor identified in nearly two decades, suggesting that understanding more about TREM2 function could provide key insights into NDD pathology and provide avenues for novel immune-related NDD biomarkers and therapeutics. The expression, signaling and function of TREM2 in NDDs have been extensively investigated in an effort to understand the role of immune function in disease pathogenesis and progression. We provide a comprehensive review of our current understanding of TREM2 biology, including new insights into the regulation of TREM2 expression, and TREM2 signaling and function across NDDs. While many open questions remain, the current body of literature provides clarity on several issues. While it is still often cited that TREM2 expression is decreased by pro-inflammatory stimuli, it is now clear that this is true in vitro, but inflammatory stimuli in vivo almost universally increase TREM2 expression. Likewise, while TREM2 function is classically described as promoting an anti-inflammatory phenotype, more than half of published studies demonstrate a pro-inflammatory role for TREM2, suggesting that its role in inflammation is much more complex. Finally, these components of TREM2 biology are applied to a discussion of how TREM2 impacts NDD pathologies and the latest assessment of how these findings might be applied to immune-directed clinical biomarkers and therapeutics.
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Affiliation(s)
- Taylor R. Jay
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
| | - Victoria E. von Saucken
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th Street, Indianapolis, IN 46202 USA
| | - Gary E. Landreth
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th Street, Indianapolis, IN 46202 USA
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Perez SE, Nadeem M, He B, Miguel JC, Malek-Ahmadi MH, Chen K, Mufson EJ. Neocortical and hippocampal TREM2 protein levels during the progression of Alzheimer's disease. Neurobiol Aging 2017; 54:133-143. [PMID: 28365005 PMCID: PMC6344038 DOI: 10.1016/j.neurobiolaging.2017.02.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/14/2017] [Accepted: 02/16/2017] [Indexed: 01/09/2023]
Abstract
Heterozygous triggering receptor expressed on myeloid cells (TREM2) mutations are an Alzheimer's disease (AD) risk factor. Nonmutated TREM2 dysregulation occurs in AD brain. Whether TREM2 is altered in prodromal AD remains unknown. Western blotting was used to determine levels of TREM2 (∼25 kDa) and Iba1 in the frontal cortex and TREM2 in the hippocampus from people who died with an ante-mortem clinical diagnosis of non- and mild-cognitive impairment, mild/moderate AD, and severe AD (sAD). Immunohistochemistry defined the relationship between amyloid and Iba1 profiles. Polymerase chain reaction analysis revealed that all subjects did not carry the most common R47H TREM2 variant. TREM2 was significantly upregulated in sAD frontal cortex but stable in hippocampus. Frontal TREM2 mRNA and protein level patterns were similar but not significantly different. Iba1 immunopositive microglia counts increased significantly in frontal cortex containing plaques in sAD. TREM2 and Iba1 levels were not associated with plaques, tangles, neuropathological criteria, or cognitive performance. Frontal cortex TREM2 upregulation is a late event and may not play a major role early in the pathogenesis of the disease.
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Affiliation(s)
- Sylvia E Perez
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Muhammad Nadeem
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Bin He
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Jennifer C Miguel
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | | | - Kewei Chen
- Banner Alzheimer's Institute, Phoenix, AZ, USA
| | - Elliott J Mufson
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA.
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