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Siew JJ, Chern Y, Khoo KH, Angata T. Roles of Siglecs in neurodegenerative diseases. Mol Aspects Med 2023; 90:101141. [PMID: 36089405 DOI: 10.1016/j.mam.2022.101141] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/16/2022] [Accepted: 08/29/2022] [Indexed: 02/08/2023]
Abstract
Microglia are resident myeloid cells in the central nervous system (CNS) with a unique developmental origin, playing essential roles in developing and maintaining the CNS environment. Recent studies have revealed the involvement of microglia in neurodegenerative diseases, such as Alzheimer's disease, through the modulation of neuroinflammation. Several members of the Siglec family of sialic acid recognition proteins are expressed on microglia. Since the discovery of the genetic association between a polymorphism in the CD33 gene and late-onset Alzheimer's disease, significant efforts have been made to elucidate the molecular mechanism underlying the association between the polymorphism and Alzheimer's disease. Furthermore, recent studies have revealed additional potential associations between Siglecs and Alzheimer's disease, implying that the reduced signal from inhibitory Siglec may have an overall protective effect in lowering the disease risk. Evidences suggesting the involvement of Siglecs in other neurodegenerative diseases are also emerging. These findings could help us predict the roles of Siglecs in other neurodegenerative diseases. However, little is known about the functionally relevant Siglec ligands in the brain, which represents a new frontier. Understanding how microglial Siglecs and their ligands in CNS contribute to the regulation of CNS homeostasis and pathogenesis of neurodegenerative diseases may provide us with a new avenue for disease prevention and intervention.
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Affiliation(s)
- Jian Jing Siew
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Kay-Hooi Khoo
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Takashi Angata
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
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Wen L, Zhang B, Wu X, Liu R, Fan H, Han L, Zhang Z, Ma X, Chu CQ, Shi X. Toll-like receptors 7 and 9 regulate the proliferation and differentiation of B cells in systemic lupus erythematosus. Front Immunol 2023; 14:1093208. [PMID: 36875095 PMCID: PMC9975558 DOI: 10.3389/fimmu.2023.1093208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 02/02/2023] [Indexed: 02/17/2023] Open
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune illness marked by the loss of immune tolerance and the production of autoantibodies against nucleic acids and other nuclear antigens (Ags). B lymphocytes are important in the immunopathogenesis of SLE. Multiple receptors control abnormal B-cell activation in SLE patients, including intrinsic Toll-like receptors (TLRs), B-cell receptors (BCRs), and cytokine receptors. The role of TLRs, notably TLR7 and TLR9, in the pathophysiology of SLE has been extensively explored in recent years. When endogenous or exogenous nucleic acid ligands are recognized by BCRs and internalized into B cells, they bind TLR7 or TLR9 to activate related signalling pathways and thus govern the proliferation and differentiation of B cells. Surprisingly, TLR7 and TLR9 appear to play opposing roles in SLE B cells, and the interaction between them is still poorly understood. In addition, other cells can enhance TLR signalling in B cells of SLE patients by releasing cytokines that accelerate the differentiation of B cells into plasma cells. Therefore, the delineation of how TLR7 and TLR9 regulate the abnormal activation of B cells in SLE may aid the understanding of the mechanisms of SLE and provide directions for TLR-targeted therapies for SLE.
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Affiliation(s)
- Luyao Wen
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Bei Zhang
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Xinfeng Wu
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Rongzeng Liu
- Department of Immunology, School of Basic Medical Sciences, Henan University of Science and Technology, Luoyang, China
| | - Hua Fan
- Office of Research & Innovation, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Lei Han
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Zhibo Zhang
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Xin Ma
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Cong-Qiu Chu
- Division of Arthritis and Rheumatic Diseases, Oregon Health & Science University and VA Portland Health Care System, Portland, OR, United States
| | - Xiaofei Shi
- Department of Rheumatology and Immunology, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
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