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Wei W, Zhang L, Xin W, Pan Y, Tatenhorst L, Hao Z, Gerner ST, Huber S, Juenemann M, Butz M, Huttner HB, Bähr M, Fitzner D, Jia F, Doeppner TR. TREM2 regulates microglial lipid droplet formation and represses post-ischemic brain injury. Biomed Pharmacother 2024; 170:115962. [PMID: 38042110 DOI: 10.1016/j.biopha.2023.115962] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/14/2023] [Accepted: 11/27/2023] [Indexed: 12/04/2023] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane receptor protein predominantly expressed in microglia within the central nervous system (CNS). TREM2 regulates multiple microglial functions, including lipid metabolism, immune reaction, inflammation, and microglial phagocytosis. Recent studies have found that TREM2 is highly expressed in activated microglia after ischemic stroke. However, the role of TREM2 in the pathologic response after stroke remains unclear. Herein, TREM2-deficient microglia exhibit an impaired phagocytosis rate and cholesteryl ester (CE) accumulation, leading to lipid droplet formation and upregulation of Perilipin-2 (PLIN2) expression after hypoxia. Knockdown of TREM2 results in increased lipid synthesis (PLIN2, SOAT1) and decreased cholesterol clearance and lipid hydrolysis (LIPA, ApoE, ABCA1, NECH1, and NPC2), further impacting microglial phenotypes. In these lipid droplet-rich microglia, the TGF-β1/Smad2/3 signaling pathway is downregulated, driving microglia towards a pro-inflammatory phenotype. Meanwhile, in a neuron-microglia co-culture system under hypoxic conditions, we found that microglia lost their protective effect against neuronal injury and apoptosis when TREM2 was knocked down. Under in vivo conditions, TREM2 knockdown mice express lower TGF-β1 expression levels and a lower number of anti-inflammatory M2 phenotype microglia, resulting in increased cerebral infarct size, exacerbated neuronal apoptosis, and aggravated neuronal impairment. Our work suggests that TREM2 attenuates stroke-induced neuroinflammation by modulating the TGF-β1/Smad2/3 signaling pathway. TREM2 may play a direct role in the regulation of inflammation and also exert an influence on the post-ischemic inflammation and the stroke pathology progression via regulation of lipid metabolism processes. Thus, underscoring the therapeutic potential of TREM2 agonists in ischemic stroke and making TREM2 an attractive new clinical target for the treatment of ischemic stroke and other inflammation-related diseases.
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Affiliation(s)
- Wei Wei
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Lin Zhang
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenqiang Xin
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Yongli Pan
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Lars Tatenhorst
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Zhongnan Hao
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Stefan T Gerner
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Sabine Huber
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Martin Juenemann
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Marius Butz
- Heart and Brain Research Group, Kerckhoff Heart and Thorax Center, Bad Nauheim, Germany
| | - Hagen B Huttner
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Mathias Bähr
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Dirk Fitzner
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.
| | - Feng Jia
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Neurosurgery, Nantong First People's Hospital, Affiliated Hospital 2 of Nantong University, Nantong, China.
| | - Thorsten R Doeppner
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany; Department of Neurology, University of Giessen Medical School, Giessen, Germany; Department of Anatomy and Cell Biology, Medical University of Varna, Varna, Bulgaria; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Giessen, Germany; Research Institute for Health Sciences and Technologies (SABITA), Medipol University, Istanbul, Turkey.
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Wu Z, Yang S, Fang X, Shu Q, Chen Q. Function and mechanism of TREM2 in bacterial infection. PLoS Pathog 2024; 20:e1011895. [PMID: 38236825 PMCID: PMC10796033 DOI: 10.1371/journal.ppat.1011895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2024] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2), which is a lipid sensing and phagocytosis receptor, plays a key role in immunity and inflammation in response to pathogens. Here, we review the function and signaling of TREM2 in microbial binding, engulfment and removal, and describe TREM2-mediated inhibition of inflammation by negatively regulating the Toll-like receptor (TLR) response. We further illustrate the role of TREM2 in restoring organ homeostasis in sepsis and soluble TREM2 (sTREM2) as a diagnostic marker for sepsis-associated encephalopathy (SAE). Finally, we discuss the prospect of TREM2 as an interesting therapeutic target for sepsis.
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Affiliation(s)
- Zehua Wu
- Department of the Clinical Research Center, Children’s Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Shiyue Yang
- Department of Anesthesiology, First Affiliated Hospital of Soochow University, Soochow, People’s Republic of China
| | - Xiangming Fang
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Qiang Shu
- Department of the Clinical Research Center, Children’s Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
- Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, People’s Republic of China
| | - Qixing Chen
- Department of the Clinical Research Center, Children’s Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
- Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, People’s Republic of China
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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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Fu XX, Chen SY, Lian HW, Deng Y, Duan R, Zhang YD, Jiang T. The TREM2 H157Y Variant Influences Microglial Phagocytosis, Polarization, and Inflammatory Cytokine Release. Brain Sci 2023; 13:brainsci13040642. [PMID: 37190607 DOI: 10.3390/brainsci13040642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/04/2023] [Accepted: 04/07/2023] [Indexed: 05/17/2023] Open
Abstract
Previously, we reported that H157Y, a rare coding variant on exon 3 of the triggering receptor expressed on myeloid cells 2 gene (TREM2), was associated with Alzheimer's disease (AD) risk in a Han Chinese population. To date, how this variant increases AD risk has remained unclear. In this study, using CRISPR-Cas9-engineered BV2 microglia, we tried to investigate the influence of the Trem2 H157Y variant on AD-related microglial functions. For the first time, we revealed that the Trem2 H157Y variant inhibits microglial phagocytosis of amyloid-β, promotes M1-type polarization of microglia, and facilitates microglial release of inflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. These findings provide new insights into the cellular mechanisms by which the TREM2 H157Y variant elevates the risk of AD.
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Affiliation(s)
- Xin-Xin Fu
- Department of Neurology, Nanjing First Hospital, China Pharmaceutical University, No.639 Longmian Road, Nanjing 211100, China
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No.68 Changle Road, Nanjing 210006, China
| | - Shuai-Yu Chen
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No.68 Changle Road, Nanjing 210006, China
| | - Hui-Wen Lian
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No.68 Changle Road, Nanjing 210006, China
| | - Yang Deng
- Department of Neurology, Nanjing First Hospital, China Pharmaceutical University, No.639 Longmian Road, Nanjing 211100, China
| | - Rui Duan
- Department of Neurology, Nanjing First Hospital, China Pharmaceutical University, No.639 Longmian Road, Nanjing 211100, China
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No.68 Changle Road, Nanjing 210006, China
| | - Ying-Dong Zhang
- Department of Neurology, Nanjing First Hospital, China Pharmaceutical University, No.639 Longmian Road, Nanjing 211100, China
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No.68 Changle Road, Nanjing 210006, China
| | - Teng Jiang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No.68 Changle Road, Nanjing 210006, China
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