1
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Waterman HR, Dufort MJ, Posso SE, Ni M, Li LZ, Zhu C, Raj P, Smith KD, Buckner JH, Hamerman JA. Lupus IgA1 autoantibodies synergize with IgG to enhance plasmacytoid dendritic cell responses to RNA-containing immune complexes. Sci Transl Med 2024; 16:eadl3848. [PMID: 38959329 PMCID: PMC11418372 DOI: 10.1126/scitranslmed.adl3848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 06/12/2024] [Indexed: 07/05/2024]
Abstract
Autoantibodies to nuclear antigens are hallmarks of systemic lupus erythematosus (SLE) where they contribute to pathogenesis. However, there remains a gap in our knowledge regarding how different isotypes of autoantibodies contribute to this autoimmune disease, including the production of the critical type I interferon (IFN) cytokines by plasmacytoid dendritic cells (pDCs) in response to immune complexes (ICs). We focused on IgA, which is the second-most prevalent isotype in serum and, along with IgG, is deposited in glomeruli in individuals with lupus nephritis. We show that individuals with SLE have serum IgA autoantibodies against most nuclear antigens, correlating with IgG against the same antigen. We investigated whether IgA autoantibodies against a major SLE autoantigen, Smith ribonucleoprotein (Sm/RNP), played a role in IC activation of pDCs. We found that pDCs expressed the IgA-specific Fc receptor, FcαR, and IgA1 autoantibodies synergized with IgG in RNA-containing ICs to generate robust primary blood pDC IFN-α responses in vitro. pDC responses to these ICs required both FcαR and FcγRIIa, showing synergy between these Fc receptors. Sm/RNP IC binding to and internalization by pDCs were greater when ICs contained both IgA1 and IgG. Circulating pDCs from individuals with SLE had higher binding of IgA1-containing ICs and higher expression of FcαR than pDCs from healthy control individuals. Although pDC FcαR expression correlated with the blood IFN-stimulated gene signature in SLE, Toll-like receptor 7 agonists, but not IFN-α, up-regulated pDC FcαR expression in vitro. Together, we show a mechanism by which IgA1 autoantibodies contribute to SLE pathogenesis.
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Affiliation(s)
- Hayley R. Waterman
- Molecular and Cell Biology Program, University of Washington; Seattle, 98195, USA
- Center for Fundamental Immunology, Benaroya Research Institute; Seattle, 98101, USA
| | - Matthew J. Dufort
- Center for Systems Immunology, Benaroya Research Institute; Seattle, 98101, USA
| | - Sylvia E. Posso
- Center for Translational Immunology, Benaroya Research Institute, 98101, USA
| | - Minjian Ni
- Center for Fundamental Immunology, Benaroya Research Institute; Seattle, 98101, USA
| | - Lucy Z. Li
- Molecular and Cell Biology Program, University of Washington; Seattle, 98195, USA
- Center for Fundamental Immunology, Benaroya Research Institute; Seattle, 98101, USA
| | - Chengsong Zhu
- Department of Immunology, Microarray and Immune Phenotyping Core Facility, University of Texas Southwestern Medical Center; Dallas, 75390, USA
| | - Prithvi Raj
- Department of Immunology, Microarray and Immune Phenotyping Core Facility, University of Texas Southwestern Medical Center; Dallas, 75390, USA
| | - Kelly D. Smith
- Department of Laboratory Medicine and Pathology, University of Washington; Seattle, 98195, USA
| | - Jane H. Buckner
- Center for Translational Immunology, Benaroya Research Institute, 98101, USA
| | - Jessica A. Hamerman
- Molecular and Cell Biology Program, University of Washington; Seattle, 98195, USA
- Center for Fundamental Immunology, Benaroya Research Institute; Seattle, 98101, USA
- Department of Immunology, University of Washington; Seattle, 98195, USA
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2
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Lorant AK, Yoshida AE, Gilbertson EA, Chu T, Stefani C, Acharya M, Hamerman JA, Lacy-Hulbert A. Integrin αvβ3 Limits Cytokine Production by Plasmacytoid Dendritic Cells and Restricts TLR-Driven Autoimmunity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 212:1680-1692. [PMID: 38607278 PMCID: PMC11105983 DOI: 10.4049/jimmunol.2300290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 03/20/2024] [Indexed: 04/13/2024]
Abstract
Plasmacytoid dendritic cells (pDCs) are strongly implicated as a major source of IFN-I in systemic lupus erythematosus (SLE), triggered through TLR-mediated recognition of nucleic acids released from dying cells. However, relatively little is known about how TLR signaling and IFN-I production are regulated in pDCs. In this article, we describe a role for integrin αvβ3 in regulating TLR responses and IFN-I production by pDCs in mouse models. We show that αv and β3-knockout pDCs produce more IFN-I and inflammatory cytokines than controls when stimulated through TLR7 and TLR9 in vitro and in vivo. Increased cytokine production was associated with delayed acidification of endosomes containing TLR ligands, reduced LC3 conjugation, and increased TLR signaling. This dysregulated TLR signaling results in activation of B cells and promotes germinal center (GC) B cell and plasma cell expansion. Furthermore, in a mouse model of TLR7-driven lupus-like disease, deletion of αvβ3 from pDCs causes accelerated autoantibody production and pathology. We therefore identify a pDC-intrinsic role for αvβ3 in regulating TLR signaling and preventing activation of autoreactive B cells. Because αvβ3 serves as a receptor for apoptotic cells and cell debris, we hypothesize that this regulatory mechanism provides important contextual cues to pDCs and functions to limit responses to self-derived nucleic acids.
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Affiliation(s)
- Alina K Lorant
- Benaroya Research Institute at Virginia Mason; Seattle, WA, USA 98101
- Department of Immunology, University of Washington; Seattle, WA, USA 98109
| | - Anna E Yoshida
- Benaroya Research Institute at Virginia Mason; Seattle, WA, USA 98101
| | | | - Talyn Chu
- Benaroya Research Institute at Virginia Mason; Seattle, WA, USA 98101
| | - Caroline Stefani
- Benaroya Research Institute at Virginia Mason; Seattle, WA, USA 98101
| | - Mridu Acharya
- Seattle Children’s Research Institute, Seattle, WA, USA 98105
| | - Jessica A Hamerman
- Benaroya Research Institute at Virginia Mason; Seattle, WA, USA 98101
- Department of Immunology, University of Washington; Seattle, WA, USA 98109
| | - Adam Lacy-Hulbert
- Benaroya Research Institute at Virginia Mason; Seattle, WA, USA 98101
- Department of Immunology, University of Washington; Seattle, WA, USA 98109
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3
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Liu S, Lagos J, Shumlak NM, Largent AD, Lewis ST, Holder U, Du SW, Liu Y, Hou B, Acharya M, Jackson SW. NADPH oxidase exerts a B cell-intrinsic contribution to lupus risk by modulating endosomal TLR signals. J Exp Med 2024; 221:e20230774. [PMID: 38442270 PMCID: PMC10913815 DOI: 10.1084/jem.20230774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 11/11/2023] [Accepted: 01/16/2024] [Indexed: 03/07/2024] Open
Abstract
Genome-wide association studies in systemic lupus erythematosus (SLE) have linked loss-of-function mutations in phagocytic NADPH oxidase complex (NOX2) genes, including NCF1 and NCF2, to disease pathogenesis. The prevailing model holds that reduced NOX2 activity promotes SLE via defective efferocytosis, the immunologically silent clearance of apoptotic cells. Here, we describe a parallel B cell-intrinsic mechanism contributing to breaks in tolerance. In keeping with an important role for B cell Toll-like receptor (TLR) pathways in lupus pathogenesis, NOX2-deficient B cells exhibit enhanced signaling downstream of endosomal TLRs, increased humoral responses to nucleic acid-containing antigens, and the propensity toward humoral autoimmunity. Mechanistically, TLR-dependent NOX2 activation promotes LC3-mediated maturation of TLR-containing endosomes, resulting in signal termination. CRISPR-mediated disruption of NCF1 confirmed a direct role for NOX2 in regulating endosomal TLR signaling in primary human B cells. Together, these data highlight a new B cell-specific mechanism contributing to autoimmune risk in NCF1 and NCF2 variant carriers.
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Affiliation(s)
- Shuozhi Liu
- Seattle Children’s Research Institute, Seattle, WA, USA
| | | | | | | | | | - Ursula Holder
- Seattle Children’s Research Institute, Seattle, WA, USA
| | - Samuel W. Du
- Seattle Children’s Research Institute, Seattle, WA, USA
| | - Yifan Liu
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Baidong Hou
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Mridu Acharya
- Seattle Children’s Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
| | - Shaun W. Jackson
- Seattle Children’s Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
- Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA, USA
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4
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Smith M, Meliopoulos V, Tan S, Bub T, Brigleb PH, Sharp B, Crawford JC, Prater MS, Pruett-Miller SM, Schultz-Cherry S. The β6 Integrin Negatively Regulates TLR7-Mediated Epithelial Immunity via Autophagy During Influenza A Virus Infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555098. [PMID: 37693589 PMCID: PMC10491108 DOI: 10.1101/2023.08.28.555098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Integrins are essential surface receptors that sense extracellular changes to initiate various intracellular signaling cascades. The rapid activation of the epithelial-intrinsic β6 integrin during influenza A virus (IAV) infection has been linked to innate immune impairments. Yet, how β6 regulates epithelial immunity remains undefined. Here, we identify the role of β6 in mediating the Toll-like receptor 7 (TLR7) through the regulation of intracellular trafficking. We demonstrate that deletion of the β6 integrin in lung epithelial cells significantly enhances the TLR7-mediated activation of the type I interferon (IFN) response during homeostasis and respiratory infection. IAV-induced β6 facilitates TLR7 trafficking to lysosome-associated membrane protein (LAMP2a) components, leading to a reduction in endosomal compartments and associated TLR7 signaling. Our findings reveal an unappreciated role of β6-induced autophagy in influencing epithelial immune responses during influenza virus infection.
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5
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Zhang Q, Zhang S, Chen J, Xie Z. The Interplay between Integrins and Immune Cells as a Regulator in Cancer Immunology. Int J Mol Sci 2023; 24:6170. [PMID: 37047140 PMCID: PMC10093897 DOI: 10.3390/ijms24076170] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/20/2023] [Accepted: 03/22/2023] [Indexed: 04/14/2023] Open
Abstract
Integrins are a group of heterodimers consisting of α and β subunits that mediate a variety of physiological activities of immune cells, including cell migration, adhesion, proliferation, survival, and immunotolerance. Multiple types of integrins act differently on the same immune cells, while the same integrin may exert various effects on different immune cells. In the development of cancer, integrins are involved in the regulation of cancer cell proliferation, invasion, migration, and angiogenesis; conversely, integrins promote immune cell aggregation to mediate the elimination of tumors. The important roles of integrins in cancer progression have provided valuable clues for the diagnosis and targeted treatment of cancer. Furthermore, many integrin inhibitors have been investigated in clinical trials to explore effective regimens and reduce side effects. Due to the complexity of the mechanism of integrin-mediated cancer progression, challenges remain in the research and development of cancer immunotherapies (CITs). This review enumerates the effects of integrins on four types of immune cells and the potential mechanisms involved in the progression of cancer, which will provide ideas for more optimal CIT in the future.
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Affiliation(s)
- Qingfang Zhang
- College of Basic Medical, Nanchang University, Nanchang 330006, China
- Queen Mary School, Medical Department, Nanchang University, Nanchang 330031, China
| | - Shuo Zhang
- College of Basic Medical, Nanchang University, Nanchang 330006, China
- Queen Mary School, Medical Department, Nanchang University, Nanchang 330031, China
| | - Jianrui Chen
- College of Basic Medical, Nanchang University, Nanchang 330006, China
- Queen Mary School, Medical Department, Nanchang University, Nanchang 330031, China
| | - Zhenzhen Xie
- College of Basic Medical, Nanchang University, Nanchang 330006, China
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6
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Muir V, Sagadiev S, Liu S, Holder U, Armendariz AM, Suchland E, Meitlis I, Camp N, Giltiay N, Tam JM, Garner EC, Wivagg CN, Shows D, James RG, Lacy-Hulbert A, Acharya M. Transcriptomic analysis of pathways associated with ITGAV/alpha(v) integrin-dependent autophagy in human B cells. Autophagy 2023; 19:926-942. [PMID: 36016494 PMCID: PMC9980515 DOI: 10.1080/15548627.2022.2113296] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Macroautophagy/autophagy proteins have been linked with the development of immune-mediated diseases including lupus, but the mechanisms for this are unclear due to the complex roles of these proteins in multiple immune cell types. We have previously shown that a form of noncanonical autophagy induced by ITGAV/alpha(v) integrins regulates B cell activation by viral and self-antigens, in mice. Here, we investigate the involvement of this pathway in B cells from human tissues. Our data reveal that autophagy is specifically induced in the germinal center and memory B cell subpopulations of human tonsils and spleens. Transcriptomic analysis show that the induction of autophagy is related to unique aspects of activated B cells such as mitochondrial metabolism. To understand the function of ITGAV/alpha(v) integrin-dependent autophagy in human B cells, we used CRISPR-mediated knockdown of autophagy genes. Integrating data from primary B cells and knockout cells, we found that ITGAV/alpha(v)-dependent autophagy limits activation of specific pathways related to B cell responses, while promoting others. These data provide new mechanistic links for autophagy and B-cell-mediated immune dysregulation in diseases such as lupus.
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Affiliation(s)
- Virginia Muir
- Immunology Program, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Sara Sagadiev
- Immunology Program, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA.,Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Shuozhi Liu
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Ursula Holder
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Andrea M Armendariz
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Emmaline Suchland
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Iana Meitlis
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Nathan Camp
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
| | - Natalia Giltiay
- Departments of Rheumatology, University of Washington, Seattle, WA, USA
| | - Jenny M Tam
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Ethan C Garner
- Department of Molecular and Cell Biology, Harvard University, Cambridge, MA, USA
| | - Carl N Wivagg
- Department of Molecular and Cell Biology, Harvard University, Cambridge, MA, USA
| | - Donna Shows
- Immunology Program, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Richard G James
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA.,Department of Pediatric, University of Washington, Seattle, WA, USA.,Department of Pharmacology, University of Washington, Seattle, WA, USA
| | - Adam Lacy-Hulbert
- Immunology Program, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA.,Department of Immunology, University of Washington, Seattle, WA, USA
| | - Mridu Acharya
- Immunology Program, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA.,Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA.,Department of Pediatric, University of Washington, Seattle, WA, USA
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7
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Israr M, Naseem N, Akhtar T, Aftab U, Zafar MS, Faheem MA, Shahzad M. Nimbolide attenuates complete Freund's adjuvant induced arthritis through expression regulation of toll-like receptors signaling pathway. Phytother Res 2023; 37:903-912. [PMID: 36437579 DOI: 10.1002/ptr.7672] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 09/15/2022] [Accepted: 10/07/2022] [Indexed: 11/29/2022]
Abstract
Nimbolide is an active constituent of Azadirachta indica and is known for its anti-inflammatory, anti-oxidant, immune-modulatory, and anti-cancer effects. Few studies suggest that nimbolide treatment influences the responses to rheumatoid arthritis, but the underlying molecular mechanisms involved are not yet well established. Therefore, the present study was designed to determine the effect of nimbolide on expression regulation of toll-like receptors to attenuate rheumatoid arthritis. The rheumatoid arthritis model was established by injecting complete Freund's adjuvant (CFA) intra-dermally into the sub-plantar region of the left hind paw of rats. Nimbolide (20 mg/kg) and piroxicam (10 mg/kg) were given to arthritic rats. Rats treated with nimbolide showed a significant reduction in inflammatory cells, rheumatoid factor, ESR, and improved the body weight. The results indicated that nimbolide possesses the capacity to attenuate rheumatoid arthritis by downregulating toll-like receptors, IL-17, IL-23, HSP70, and IFN-γ expression levels. Nimbolide treatment showed significant reduction in the severity of inflammation and destruction of joints and showed comparable effects to piroxicam, which is a standard non-steroidal anti-inflammatory drug used for the treatment of rheumatoid arthritis. It can be concluded that nimbolide can be considered as a potential candidate for therapeutic targeting of the toll-like receptors pathway in rheumatoid arthritis.
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Affiliation(s)
- Maham Israr
- Department of Pharmacology, University of Health Sciences, Lahore, Pakistan
| | - Nadia Naseem
- Department of Morbid Anatomy and Histopathology, University of Health Sciences, Lahore, Pakistan
| | - Tasleem Akhtar
- Department of Pharmacology, University of Health Sciences, Lahore, Pakistan
| | - Usman Aftab
- Department of Pharmacology, University of Health Sciences, Lahore, Pakistan
| | | | | | - Muhammad Shahzad
- Department of Pharmacology, University of Health Sciences, Lahore, Pakistan
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8
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Wu J, Jin YY, Gong RL, Yang F, Su XY, Chen TX. Genome-Wide ChIP-seq and RNA-seq Analyses of STAT3 Target Genes in TLRs Activated Human Peripheral Blood B Cells. Front Immunol 2022; 13:821457. [PMID: 35345674 PMCID: PMC8957201 DOI: 10.3389/fimmu.2022.821457] [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: 12/03/2021] [Accepted: 02/10/2022] [Indexed: 11/29/2022] Open
Abstract
Toll like receptors (TLRs) induced response plays a vital role in B-cell development and activation, in which TLR7-mediated and TLR9-mediated response interact together and play antagonistic or cooperative roles at different situations. Previous studies showed that the transcription factor signal transducer and activator of transcription (STAT) 3 was one of the key transcriptional factors (TFs) needed for both TLR7 and TLR9 signaling in B cell, and patients with autosomal dominant hyper IgE syndromes (AD-HIES) due to STAT3 mutations having defective TLRs response in B cells. However, how STAT3 affects its target genes and the downstream signaling pathways in B cell upon TLRs stimulation remains unclarified on a genome-wide level. ChIP-seq and RNA-seq was used in this study to identify the STAT3 targets in response to TLRs stimulation in human B cell. STAT3 ChIP-seq results showed a total of 611 and 2,289 differential STAT3-binding sites in human B cell after TLR7 and TLR9 agonists stimulation, respectively. RNA-seq results showed 1,186 and 1,775 differentially expressed genes after TLR7 and TLR9 activation, respectively. We identified 47 primary STAT3 target genes after TLR7 activation and 189 target genes after TLR9 activation in B cell by integration of STAT3 ChIP-seq and RNA-seq data. Among these STAT3 primary targets, we identified 7 TFs and 18 TFs for TLR7 and TLR9 response, respectively. Besides, we showed that STAT3 might regulate TLR9, but not TLR7 response in B cells through directly regulating integrin signaling pathway, which might further affect the antagonism between TLR7 and TLR9 signaling in B cell. Our study provides insights into the molecular mechanism of human TLRs response in B cell and how it can be regulated, which helps to better understand and modulate TLR-mediated pathogenic immune responses in B cell.
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Affiliation(s)
- Jing Wu
- Division of Immunology, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Allergy/Immunology Innovation Team, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ying-Ying Jin
- Allergy/Immunology Innovation Team, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Department of Rheumatology/Immunology, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ruo-Lan Gong
- Division of Immunology, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Fan Yang
- Division of Immunology, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao-Ya Su
- Division of Immunology, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Tong-Xin Chen
- Division of Immunology, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Allergy/Immunology Innovation Team, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Department of Rheumatology/Immunology, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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9
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Acharya M, Jackson SW. Regulatory strategies limiting endosomal Toll-like receptor activation in B cells. Immunol Rev 2022; 307:66-78. [PMID: 35040152 PMCID: PMC8986562 DOI: 10.1111/imr.13065] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 01/07/2022] [Indexed: 12/26/2022]
Abstract
The recognition of pathogen-associated nucleic acid (NA) promotes effective immunity against invading pathogens. However, endosomal Toll-like receptor (TLR) activation by self-NA also underlies the pathogenesis of systemic autoimmune diseases, such as systemic lupus erythematosus (SLE). For this reason, the activation thresholds of NA-sensing TLRs must be tightly regulated to balance protective and pathogenic immune responses. In this study, we will provide an overview of the evolutionary mechanisms designed to limit the aberrant activation of endosomal TLRs by self-ligands, focusing on four broad strategies. These include the following: 1) the production of nucleases able to degrade self-DNA and RNA; 2) the cell-specific regulation of endosomal TLR expression; 3) the spatial and temporal control of TLR positioning at a sub-cellular level; and 4) the modulation of downstream TLR signaling cascades. Given the critical role of B cells in lupus pathogenesis, where possible, we will describe evidence for B cell-specific induction of these regulatory mechanisms. We will also highlight our own work showing how modulation of B cell endolysosomal flux tunes NA-sensing TLR activation signals. In the face of inevitable generation of self-NA during normal cellular turnover, these parallel mechanisms are vital to protect against pathogenic inflammation.
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Affiliation(s)
- Mridu Acharya
- Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA.,Seattle Children's Research Institute, Seattle, Washington, USA
| | - Shaun W Jackson
- Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA.,Seattle Children's Research Institute, Seattle, Washington, USA
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10
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Satterthwaite AB. TLR7 Signaling in Lupus B Cells: New Insights into Synergizing Factors and Downstream Signals. Curr Rheumatol Rep 2021; 23:80. [PMID: 34817709 DOI: 10.1007/s11926-021-01047-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2021] [Indexed: 12/19/2022]
Abstract
PURPOSE OF THE REVIEW Systemic lupus erythematosus (SLE) is driven by nucleic acid-containing antigens that stimulate endosomal TLRs. We review new advances in our understanding of how TLR7 signaling in B cells drives autoimmunity. RECENT FINDINGS Pathogenic B cell responses to TLR7 engagement are shaped by the disease-associated cytokine environment. TLR7, IFNγ, and IL-21 together promote the formation of autoreactive germinal centers and the ABC/DN2 B cell subset. BAFF and type 1 IFNs enhance autoantibody production from transitional B cells in concert with TLR7. TLR7 signaling components STAT1, BANK1, IRF5, SLC15A4, and CXorf21/TASL are associated genetically with SLE and important for lupus development in mice, while role of T-bet is controversial. Proper control of TLR7 trafficking by UNC93B1, syntenin-1, and αvβ3 integrin is critical for preventing autoimmunity. A better understanding of TLR7 signaling has revealed potential new therapeutic approaches for SLE, several of which are being tested in animal models or clinical trials.
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Affiliation(s)
- Anne B Satterthwaite
- Department of Internal Medicine, Rheumatic Diseases Division and Department of Immunology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390-8884, USA.
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