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Gurwicz N, Stoler-Barak L, Schwan N, Bandyopadhyay A, Meyer-Hermann M, Shulman Z. Tingible body macrophages arise from lymph node-resident precursors and uptake B cells by dendrites. J Exp Med 2023; 220:213834. [PMID: 36705667 PMCID: PMC9900388 DOI: 10.1084/jem.20222173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/28/2023] Open
Abstract
Antibody affinity maturation depends on the formation of germinal centers (GCs) in lymph nodes. This process generates a massive number of apoptotic B cells, which are removed by a specialized subset of phagocytes, known as tingible body macrophages (TBMs). Although defects in these cells are associated with pathological conditions, the identity of their precursors and the dynamics of dying GC B cell disposal remained unknown. Here, we demonstrate that TBMs originate from pre-existing lymph node-resident precursors that enter the lymph node follicles in a GC-dependent manner. Intravital imaging shows that TBMs are stationary cells that selectively phagocytose GC B cells via highly dynamic protrusions and accommodate the final stages of B cell apoptosis. Cell-specific depletion and chimeric mouse models revealed that GC B cells drive TBM formation from bone marrow-derived precursors stationed within lymphoid organs prior to the immune challenge. Understanding TBM dynamics and function may explain the emergence of various antibody-mediated autoimmune conditions.
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Affiliation(s)
- Neta Gurwicz
- Department of Systems Immunology, Weizmann Institute of Science , Rehovot, Israel
| | - Liat Stoler-Barak
- Department of Systems Immunology, Weizmann Institute of Science , Rehovot, Israel
| | - Niklas Schwan
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research , Braunschweig, Germany
| | - Arnab Bandyopadhyay
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research , Braunschweig, Germany
| | - Michael Meyer-Hermann
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research , Braunschweig, Germany.,Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig , Braunschweig, Germany
| | - Ziv Shulman
- Department of Systems Immunology, Weizmann Institute of Science , Rehovot, Israel
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2
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Dirks J, Haase G, Cantaert T, Frey L, Klaas M, Rickert CH, Girschick H, Meffre E, Morbach H. A Novel AICDA Splice-Site Mutation in Two Siblings with HIGM2 Permits Somatic Hypermutation but Abrogates Mutational Targeting. J Clin Immunol 2022; 42:771-782. [PMID: 35246784 PMCID: PMC9166864 DOI: 10.1007/s10875-022-01233-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/14/2022] [Indexed: 11/29/2022]
Abstract
Hyper-IgM syndrome type 2 (HIGM2) is a B cell intrinsic primary immunodeficiency caused by mutations in AICDA encoding activation-induced cytidine deaminase (AID) which impair immunoglobulin class switch recombination (CSR) and somatic hypermutation (SHM). Whereas autosomal-recessive AID-deficiency (AR-AID) affects both CSR and SHM, the autosomal-dominant form (AD-AID) due to C-terminal heterozygous variants completely abolishes CSR but only partially affects SHM. AR-AID patients display enhanced germinal center (GC) reactions and autoimmune manifestations, which are not present in AD-AID, suggesting that SHM but not CSR regulates GC reactions and peripheral B cell tolerance. Herein, we describe two siblings with HIGM2 due to a novel homozygous AICDA mutation (c.428-1G > T) which disrupts the splice acceptor site of exon 4 and results in the sole expression of a truncated AID variant that lacks 10 highly conserved amino acids encoded by exon 4 (AID-ΔE4a). AID-ΔE4a patients suffered from defective CSR and enhanced GC reactions and were therefore indistinguishable from other AR-AID patients. However, the AID-ΔE4a variant only partially affected SHM as observed in AD-AID patients. In addition, AID-ΔE4a but not AD-AID patients revealed impaired targeting of mutational hotspot motives and distorted mutational patterns. Hence, qualitative defects in AID function and altered SHM rather than global decreased SHM activity may account for the disease phenotype in these patients.
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Affiliation(s)
- Johannes Dirks
- Pediatric Immunology, University Childrens' Hospital Würzburg, Würzburg, Germany
| | - Gabriele Haase
- Pediatric Immunology, University Childrens' Hospital Würzburg, Würzburg, Germany
| | - Tineke Cantaert
- Immunology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Lea Frey
- Institute of Pathology, Würzburg University, Würzburg, Germany
| | - Moritz Klaas
- Pediatric Rheumatology, Vivantes Hospital Friedrichshain, Berlin, Germany
| | | | - Hermann Girschick
- Pediatric Rheumatology, Vivantes Hospital Friedrichshain, Berlin, Germany
- German Center for Growth and Development "DEUZWEG", Berlin, Germany
| | - Eric Meffre
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Henner Morbach
- Pediatric Immunology, University Childrens' Hospital Würzburg, Würzburg, Germany.
- Center for Rare Diseases - Reference Center Northern Bavaria (ZESE), Würzburg, Germany.
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3
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Tan Q, Tai N, Li Y, Pearson J, Pennetti S, Zhou Z, Wong FS, Wen L. Activation-induced cytidine deaminase deficiency accelerates autoimmune diabetes in NOD mice. JCI Insight 2018; 3:95882. [PMID: 29321370 DOI: 10.1172/jci.insight.95882] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 12/05/2017] [Indexed: 01/15/2023] Open
Abstract
B cells play an important role in type 1 diabetes (T1D) development. However, the role of B cell activation-induced cytidine deaminase (AID) in diabetes development is not clear. We hypothesized that AID is important in the immunopathogenesis of T1D. To test this hypothesis, we generated AID-deficient (AID-/-) NOD mice. We found that AID-/-NOD mice developed accelerated T1D, with worse insulitis and high levels of anti-insulin autoantibody in the circulation. Interestingly, neither maternal IgG transferred through placenta, nor IgA transferred through milk affected the accelerated diabetes development. AID-/-NOD mice showed increased activation and proliferation of B and T cells. We found enhanced T-B cell interactions in AID-/-NOD mice, with increased T-bet and IFN-γ expression in CD4+ T cells in the presence of AID-/- B cells. Moreover, excessive lymphoid expansion was observed in AID-/-NOD mice. Importantly, antigen-specific BDC2.5 CD4+ T cells caused more rapid onset of diabetes when cotransferred with AID-/- B cells than when cotransferred with AID+/+ B cells. Thus, our study provides insights into the role of AID in T1D. Our data also suggest that AID is a negative regulator of immune tolerance and ablation of AID can lead to exacerbated islet autoimmunity and accelerated T1D development.
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Affiliation(s)
- Qiyuan Tan
- Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha,Hunan, China.,Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Endocrinology and Metabolism, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Ningwen Tai
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Yangyang Li
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Endocrinology, Jilin University, Changchun, China
| | - James Pearson
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Sean Pennetti
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.,School of Medicine, Quinnipiac University, North Haven, Connecticut, USA
| | - Zhiguang Zhou
- Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha,Hunan, China
| | - F Susan Wong
- Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Li Wen
- Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha,Hunan, China.,Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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4
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Pan M, Zhou Y, Wang Y, Li L, Song Y, Hou L, Zhao J. Screening and Identification of the Host Proteins Interacting with Toxoplasma gondii Rhoptry Protein ROP16. Front Microbiol 2017; 8:2408. [PMID: 29255456 PMCID: PMC5722834 DOI: 10.3389/fmicb.2017.02408] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 11/20/2017] [Indexed: 01/04/2023] Open
Abstract
Toxoplasma gondii, as a zoonotic protozoan parasite, develops sophisticated strategies to manipulate hosts for efficient intracellular survival. After successful invasion, T. gondii injects many effector proteins into host cells for various purposes. TgROP16 (T. gondii rhoptry protein 16), which is secreted from rhoptries into host cells, can activate the host STAT (signal transducer and activator of transcription) signaling pathway through phosphorylation of STAT3 and STAT6. However, whether there are other host proteins modulated by TgROP16 is currently unknown. In this study, yeast two-hybrid (Y2H) screen was used to look for additional host proteins interacting with TgROP16. Yeast cells expressing a mouse cDNA library cloned into the prey vector were used to mate with yeasts expressing ROP16 without signal peptide. Two mouse proteins, Dnaja1 (DnaJ heat shock protein family member A1) and Gabra4 (gamma-aminobutyric acid A receptor, subunit alpha 4) were identified to interact with ROP16 from this screen. Further analysis suggested that the Predomain of ROP16 played key roles in mediating interactions with these host proteins, whereas the contribution from the Kinase domain was minor. The interactions between Dnaja1 and different parts of ROP16 were also estimated in vivo by co-immunoprecipitation. The results showed that the Predomain of ROP16 was the major region to interact with Dnaja1, which is consistent with the Y2H results. Based on the gene ontology analysis, Dnaja1 is predicted to participate in stress response while Gabra4 is involved in the system development process. The discovery of new host proteins that interact with ROP16 of T. gondii will help us to further investigate the functions of this effector proteins during T. gondii infection.
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Affiliation(s)
- Ming Pan
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yanqin Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory for Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, China.,Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Yifan Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Longjiao Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yongle Song
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Lun Hou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Junlong Zhao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory for Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, China.,Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
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5
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Drury RE, O'Connor D, Pollard AJ. The Clinical Application of MicroRNAs in Infectious Disease. Front Immunol 2017; 8:1182. [PMID: 28993774 PMCID: PMC5622146 DOI: 10.3389/fimmu.2017.01182] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/06/2017] [Indexed: 12/19/2022] Open
Abstract
MicroRNAs (miRNAs) are short single-stranded non-coding RNA sequences that posttranscriptionally regulate up to 60% of protein encoding genes. Evidence is emerging that miRNAs are key mediators of the host response to infection, predominantly by regulating proteins involved in innate and adaptive immune pathways. miRNAs can govern the cellular tropism of some viruses, are implicated in the resistance of some individuals to infections like HIV, and are associated with impaired vaccine response in older people. Not surprisingly, pathogens have evolved ways to undermine the effects of miRNAs on immunity. Recognition of this has led to new experimental treatments, RG-101 and Miravirsen—hepatitis C treatments which target host miRNA. miRNAs are being investigated as novel infection biomarkers, and they are being used to design attenuated vaccines, e.g., against Dengue virus. This comprehensive review synthesizes current knowledge of miRNA in host response to infection with emphasis on potential clinical applications, along with an evaluation of the challenges still to be overcome.
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Affiliation(s)
- Ruth E Drury
- Oxford Vaccine Group, Centre for Clinical Vaccinology and Tropical Medicine, Department of Paediatrics, University of Oxford, The Churchill Hospital, Oxford, United Kingdom
| | - Daniel O'Connor
- Oxford Vaccine Group, Centre for Clinical Vaccinology and Tropical Medicine, Department of Paediatrics, University of Oxford, The Churchill Hospital, Oxford, United Kingdom
| | - Andrew J Pollard
- Oxford Vaccine Group, Centre for Clinical Vaccinology and Tropical Medicine, Department of Paediatrics, University of Oxford, The Churchill Hospital, Oxford, United Kingdom
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6
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Sindhava VJ, Oropallo MA, Moody K, Naradikian M, Higdon LE, Zhou L, Myles A, Green N, Nündel K, Stohl W, Schmidt AM, Cao W, Dorta-Estremera S, Kambayashi T, Marshak-Rothstein A, Cancro MP. A TLR9-dependent checkpoint governs B cell responses to DNA-containing antigens. J Clin Invest 2017; 127:1651-1663. [PMID: 28346226 DOI: 10.1172/jci89931] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 01/26/2017] [Indexed: 01/07/2023] Open
Abstract
Mature B cell pools retain a substantial proportion of polyreactive and self-reactive clonotypes, suggesting that activation checkpoints exist to reduce the initiation of autoreactive B cell responses. Here, we have described a relationship among the B cell receptor (BCR), TLR9, and cytokine signals that regulate B cell responses to DNA-containing antigens. In both mouse and human B cells, BCR ligands that deliver a TLR9 agonist induce an initial proliferative burst that is followed by apoptotic death. The latter mechanism involves p38-dependent G1 cell-cycle arrest and subsequent intrinsic mitochondrial apoptosis and is shared by all preimmune murine B cell subsets and CD27- human B cells. Survival or costimulatory signals rescue B cells from this fate, but the outcome varies depending on the signals involved. B lymphocyte stimulator (BLyS) engenders survival and antibody secretion, whereas CD40 costimulation with IL-21 or IFN-γ promotes a T-bet+ B cell phenotype. Finally, in vivo immunization studies revealed that when protein antigens are conjugated with DNA, the humoral immune response is blunted and acquires features associated with T-bet+ B cell differentiation. We propose that this mechanism integrating BCR, TLR9, and cytokine signals provides a peripheral checkpoint for DNA-containing antigens that, if circumvented by survival and differentiative cues, yields B cells with the autoimmune-associated T-bet+ phenotype.
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7
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Boulianne B, Rojas OL, Haddad D, Zaheen A, Kapelnikov A, Nguyen T, Li C, Hakem R, Gommerman JL, Martin A. AID and caspase 8 shape the germinal center response through apoptosis. THE JOURNAL OF IMMUNOLOGY 2013; 191:5840-7. [PMID: 24244021 DOI: 10.4049/jimmunol.1301776] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Germinal centers (GCs) are clusters of activated B cells that form in secondary lymphoid organs during a T-dependent immune response. B cells enter GCs and become rapidly proliferating centroblasts that express the enzyme activation-induced deaminase (AID) to undergo somatic hypermutation and class-switch recombination. Centroblasts then mature into centrocytes to undergo clonal selection. Within the GC, the highest affinity B cell clones are selected to mature into memory or plasma cells while lower affinity clones undergo apoptosis. We reported previously that murine Aicda(-/-) GC B cells have enhanced viability and accumulate in GCs. We now show that murine Aicda(-/-) GC B cells accumulate as centrocytes and inefficiently generate plasma cells. The reduced rate of plasma cell formation was not due to an absence of AID-induced DNA lesions. In addition, we show that the deletion of caspase 8 specifically in murine GC-B cells results in larger GCs and a delay in affinity maturation, demonstrating the importance of apoptosis in GC homeostasis and clonal selection.
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Affiliation(s)
- Bryant Boulianne
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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8
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Scholz JL, Oropallo MA, Sindhava V, Goenka R, Cancro MP. The role of B lymphocyte stimulator in B cell biology: implications for the treatment of lupus. Lupus 2013; 22:350-60. [PMID: 23553778 DOI: 10.1177/0961203312469453] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
B lymphocyte stimulator (BLyS; also known as B cell activating factor (BAFF)) plays a key role in peripheral B cell tolerance. Mounting evidence indicates that B cell tolerance can be either broken or modulated by deliberately manipulating BLyS levels, and belimumab, a BLyS-neutralizing antibody, was recently approved for the treatment of systemic lupus erythematosus (SLE). Thus, intense investigation has focused on understanding how therapeutics targeting BLyS may work, and accumulating evidence suggests multiple points of action. BLyS signaling, in conjunction with B cell receptor (BCR) signaling, determines the size and quality of the mature primary B cell compartment. Moreover, BLyS family members play roles in antigen-experienced B cell selection and differentiation. Together, these findings have implications for the continued development of novel therapeutics that target BLyS.
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Affiliation(s)
- J L Scholz
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104-6082, USA
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9
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Ha SY, Sung J, Ju H, Karube K, Kim SJ, Kim WS, Seto M, Ko YH. Epstein–Barr virus-positive nodal peripheral T cell lymphomas: Clinicopathologic and gene expression profiling study. Pathol Res Pract 2013; 209:448-54. [DOI: 10.1016/j.prp.2013.04.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 04/19/2013] [Accepted: 04/20/2013] [Indexed: 02/05/2023]
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10
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Abstract
A large antibody repertoire is generated in developing B cells in the bone marrow. Before these B cells achieve immunocompetence, those expressing autospecificities must be purged. To that end, B cells within the bone marrow and just following egress from the bone marrow are subject to tolerance induction. Once B cells achieve immunocompetence, the antibody repertoire can be further diversified by somatic hypermutation of immunoglobulin genes in B cells that have been activated by antigen and cognate T cell help and have undergone a germinal center (GC) response. This process also leads to the generation of autoreactive B cells which must be again purged to protect the host. Thus, B cells within the GC and just following egress from the GC are also subject to tolerance induction. Available data suggest that B cell intrinsic processes triggered by signaling through the B cell receptor activate tolerance mechanisms at both time points. Recent data suggest that GC and post-GC B cells are also subject to B cell extrinsic tolerance mechanisms mediated through soluble and membrane-bound factors derived from various T cell subsets.
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11
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The biochemistry of activation-induced deaminase and its physiological functions. Semin Immunol 2012; 24:255-63. [DOI: 10.1016/j.smim.2012.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 05/18/2012] [Indexed: 01/26/2023]
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12
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Oropallo MA, Kiefer K, Marshak-Rothstein A, Cancro MP. Beyond transitional selection: New roles for BLyS in peripheral tolerance. Drug Dev Res 2011; 72:779-787. [PMID: 22323842 DOI: 10.1002/ddr.20487] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
B cell targeted therapies have enjoyed recent success in the treatment of systemic autoimmune diseases. Among these, Belimumab, which blocks the B cell survival cytokine BLyS, was recently approved for the treatment of Systemic Lupus Erythematosus. It is therefore important to consider the roles BLyS plays in B cell tolerance. Herein, we review how BLyS contributes to the negative selection of autoreactive B cell clones from the preimmune repertoire as well as its role in regulating both germinal center and extrafollicular peripheral B cell responses. We further examine the complex role of Toll-like receptors (TLRs) in humoral autoimmunity, pointing out potential crosstalk between BLyS and TLR pathways.
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Affiliation(s)
- Michael A Oropallo
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104-6082
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13
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Orthwein A, Zahn A, Methot SP, Godin D, Conticello SG, Terada K, Di Noia JM. Optimal functional levels of activation-induced deaminase specifically require the Hsp40 DnaJa1. EMBO J 2011; 31:679-91. [PMID: 22085931 DOI: 10.1038/emboj.2011.417] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 10/19/2011] [Indexed: 11/09/2022] Open
Abstract
The enzyme activation-induced deaminase (AID) deaminates deoxycytidine at the immunoglobulin genes, thereby initiating antibody affinity maturation and isotype class switching during immune responses. In contrast, off-target DNA damage caused by AID is oncogenic. Central to balancing immunity and cancer is AID regulation, including the mechanisms determining AID protein levels. We describe a specific functional interaction between AID and the Hsp40 DnaJa1, which provides insight into the function of both proteins. Although both major cytoplasmic type I Hsp40s, DnaJa1 and DnaJa2, are induced upon B-cell activation and interact with AID in vitro, only DnaJa1 overexpression increases AID levels and biological activity in cell lines. Conversely, DnaJa1, but not DnaJa2, depletion reduces AID levels, stability and isotype switching. In vivo, DnaJa1-deficient mice display compromised response to immunization, AID protein and isotype switching levels being reduced by half. Moreover, DnaJa1 farnesylation is required to maintain, and farnesyltransferase inhibition reduces, AID protein levels in B cells. Thus, DnaJa1 is a limiting factor that plays a non-redundant role in the functional stabilization of AID.
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Affiliation(s)
- Alexandre Orthwein
- Laboratory of Mechanisms of Genetic Diversity, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
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14
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Dimitrova P, Vassilev T, Shivarov V. Inhibition or overactivation of AICDA to eliminate pathologic B cell clones? Comment on the article by Hsu et al. ACTA ACUST UNITED AC 2011; 63:3174-5; author reply 3175-7. [PMID: 21656511 DOI: 10.1002/art.30491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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