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Xiao X, Fu Y, You W, Huang C, Zeng F, Gu X, Sun X, Li J, Zhang Q, Du W, Cheng G, Liu Z, Liu L. Inhibition of the RLR signaling pathway by SARS-CoV-2 ORF7b is mediated by MAVS and abrogated by ORF7b-homologous interfering peptide. J Virol 2024; 98:e0157323. [PMID: 38572974 PMCID: PMC11092349 DOI: 10.1128/jvi.01573-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/15/2024] [Indexed: 04/05/2024] Open
Abstract
Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and characterized by dysregulated immune response. Studies have shown that the SARS-CoV-2 accessory protein ORF7b induces host cell apoptosis through the tumor necrosis factor alpha (TNF-α) pathway and blocks the production of interferon beta (IFN-β). The underlying mechanism remains to be investigated. In this study, we found that ORF7b facilitated viral infection and production, and inhibited the RIG-I-like receptor (RLR) signaling pathway through selectively interacting with mitochondrial antiviral-signaling protein (MAVS). MAVS439-466 region and MAVS Lys461 were essential for the physical association between MAVS and ORF7b, and the inhibition of the RLR signaling pathway by ORF7b. MAVSK461/K63 ubiquitination was essential for the RLR signaling regulated by the MAVS-ORF7b complex. ORF7b interfered with the recruitment of tumor necrosis factor receptor-related factor 6 (TRAF6) and the activation of the RLR signaling pathway by MAVS. Furthermore, interfering peptides targeting the ORF7b complex reversed the ORF7b-suppressed MAVS-RLR signaling pathway. The most potent interfering peptide V disrupts the formation of ORF7b tetramers, reverses the levels of the ORF7b-inhibited physical association between MAVS and TRAF6, leading to the suppression of viral growth and infection. Overall, this study provides a mechanism for the suppression of innate immunity by SARS-CoV-2 infection and the mechanism-based approach via interfering peptides to potentially prevent SARS-CoV-2 infection.IMPORTANCEThe pandemic coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and continues to be a threat to public health. It is imperative to understand the biology of SARS-CoV-2 infection and find approaches to prevent SARS-CoV-2 infection and ameliorate COVID-19. Multiple SARS-CoV-2 proteins are known to function on the innate immune response, but the underlying mechanism remains unknown. This study shows that ORF7b inhibits the RIG-I-like receptor (RLR) signaling pathway through the physical association between ORF7b and mitochondrial antiviral-signaling protein (MAVS), impairing the K63-linked MAVS polyubiquitination and its recruitment of tumor necrosis factor receptor-related factor 6 (TRAF6) to MAVS. The most potent interfering peptide V targeting the ORF7b-MAVS complex may reverse the suppression of the MAVS-mediated RLR signaling pathway by ORF7b and prevent viral infection and production. This study may provide new insights into the pathogenic mechanism of SARS-CoV-2 and a strategy to develop new drugs to prevent SARS-CoV-2 infection.
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Affiliation(s)
- Xiao Xiao
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China
| | - Yanan Fu
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
| | - Wanling You
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
| | - Congcong Huang
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China
| | - Feng Zeng
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
| | - Xinsheng Gu
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
| | - Xiaoguang Sun
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
| | - Jian Li
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
| | - Qiwei Zhang
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Weixing Du
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
| | - Gong Cheng
- New Cornerstone Science Laboratory, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, China
| | - Zhixin Liu
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China
| | - Long Liu
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
- Institute of Virology, Shiyan Key Laboratory of Virology, Hubei University of Medicine, Shiyan, China
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China
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Determination of T Cell Responses in Thai Systemic Sclerosis Patients. J Immunol Res 2022; 2022:5072154. [PMID: 35310606 PMCID: PMC8924789 DOI: 10.1155/2022/5072154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/12/2022] [Accepted: 02/21/2022] [Indexed: 11/17/2022] Open
Abstract
Objectives This study is aimed at determining the role of T cells by assessing the numbers of IFN-γ- and IL-2-secreting T cells following stimulation with peptides derived from DNA topoisomerase-I protein in Thai SSc patients. Methods Fifty Thai SSc patients and 50 healthy controls (HC) joined this study. IFN-γ and IL-2 levels upon stimulation of T cells with 6 peptides derived from DNA topoisomerase-I protein were determined. Anti-nuclear antibodies (ANA) and anti-Scl-70 antibodies were determined by using the ELISA method. Results In SSc patients, we detected a significantly higher number of IFN-γ- and IL-2-secreting CD8+ T cells than IFN-γ- and IL-2-secreting CD4+ T cells after stimulation with pooled peptides derived from DNA topoisomerase-I protein. A similar percentage of CD4+IL-2+, CD4+IFN-γ+, and CD8+IL-2+ were detected following stimulation with DNA topoisomerase-I protein -in SSc patients with anti-Scl-70 antibody (SSc/anti-Scl-70+) and those without. In contrast, the amount of CD8+IFN-γ+ cells was significantly higher in SSc/anti-Scl-70+ than those without. Stimulation with individual peptides showed that CSLRVEHINLHPELD (sPep3; 15 amino acids; position 505-519 of DNA topoisomerase-I protein) was the optimal epitope that induced T cells secreting the highest levels of IFN-γ and IL-2. A higher percentage of IFN-γ+CD4+ T cells was detected in SSc/anti-Scl-70+ than those without the following stimulation with peptides 2 (amino acid position 475-486 [RAVALYFIDKLA] of protein DNA topoisomerase). Conclusion The results from this study emphasize the critical role of DNA topoisomerase-I peptides on the activation of T cells in SSc patients. The findings provide a better understanding of SSc's immunopathogenesis and may lead to the development of diagnostic tools and specific treatments for SSc in the future.
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Towards Clinical Translation of CD8 + Regulatory T Cells Restricted by Non-Classical Major Histocompatibility Complex Ib Molecules. Int J Mol Sci 2019; 20:ijms20194829. [PMID: 31569411 PMCID: PMC6801908 DOI: 10.3390/ijms20194829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/27/2019] [Accepted: 09/27/2019] [Indexed: 11/17/2022] Open
Abstract
In central lymphoid tissues, mature lymphocytes are generated and pathogenic autoreactive lymphocytes are deleted. However, it is currently known that a significant number of potentially pathogenic autoreactive lymphocytes escape the deletion and populate peripheral lymphoid tissues. Therefore, peripheral mechanisms are present to prevent these potentially pathogenic autoreactive lymphocytes from harming one’s own tissues. One such mechanism is dictated by regulatory T (Treg) cells. So far, the most extensively studied Treg cells are CD4+Foxp3+ Treg cells. However, recent clinical trials for the treatment of immune-mediated diseases using CD4+ Foxp3+ Treg cells met with limited success. Accordingly, it is necessary to explore the potential importance of other Treg cells such as CD8+ Treg cells. In this regard, one extensively studied CD8+ Treg cell subset is Qa-1(HLA-E in human)-restricted CD8+ Treg cells, in which Qa-1(HLA-E) molecules belong to a group of non-classical major histocompatibility complex Ib molecules. This review will first summarize the evidence for the presence of Qa-1-restricted CD8+ Treg cells and their regulatory mechanisms. Major discussions will then focus on the potential clinical translation of Qa-1-restricted CD8+ Treg cells. At the end, we will briefly discuss the current status of human studies on HLA-E-restricted CD8+ Treg cells as well as potential future directions.
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