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A multimorphic mutation in IRF4 causes human autosomal dominant combined immunodeficiency. Sci Immunol 2023; 8:eade7953. [PMID: 36662884 PMCID: PMC10825898 DOI: 10.1126/sciimmunol.ade7953] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/22/2022] [Indexed: 01/22/2023]
Abstract
Interferon regulatory factor 4 (IRF4) is a transcription factor (TF) and key regulator of immune cell development and function. We report a recurrent heterozygous mutation in IRF4, p.T95R, causing an autosomal dominant combined immunodeficiency (CID) in seven patients from six unrelated families. The patients exhibited profound susceptibility to opportunistic infections, notably Pneumocystis jirovecii, and presented with agammaglobulinemia. Patients' B cells showed impaired maturation, decreased immunoglobulin isotype switching, and defective plasma cell differentiation, whereas their T cells contained reduced TH17 and TFH populations and exhibited decreased cytokine production. A knock-in mouse model of heterozygous T95R showed a severe defect in antibody production both at the steady state and after immunization with different types of antigens, consistent with the CID observed in these patients. The IRF4T95R variant maps to the TF's DNA binding domain, alters its canonical DNA binding specificities, and results in a simultaneous multimorphic combination of loss, gain, and new functions for IRF4. IRF4T95R behaved as a gain-of-function hypermorph by binding to DNA with higher affinity than IRF4WT. Despite this increased affinity for DNA, the transcriptional activity on IRF4 canonical genes was reduced, showcasing a hypomorphic activity of IRF4T95R. Simultaneously, IRF4T95R functions as a neomorph by binding to noncanonical DNA sites to alter the gene expression profile, including the transcription of genes exclusively induced by IRF4T95R but not by IRF4WT. This previously undescribed multimorphic IRF4 pathophysiology disrupts normal lymphocyte biology, causing human disease.
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LAPTM5 mediates immature B cell apoptosis and B cell tolerance by regulating the WWP2-PTEN-AKT pathway. Proc Natl Acad Sci U S A 2022; 119:e2205629119. [PMID: 36037365 PMCID: PMC9457450 DOI: 10.1073/pnas.2205629119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Elimination of autoreactive developing B cells is an important mechanism to prevent autoantibody production. However, how B cell receptor (BCR) signaling triggers apoptosis of immature B cells remains poorly understood. We show that BCR stimulation up-regulates the expression of the lysosomal-associated transmembrane protein 5 (LAPTM5), which in turn triggers apoptosis of immature B cells through two pathways. LAPTM5 causes BCR internalization, resulting in decreased phosphorylation of SYK and ERK. In addition, LAPTM5 targets the E3 ubiquitin ligase WWP2 for lysosomal degradation, resulting in the accumulation of its substrate PTEN. Elevated PTEN levels suppress AKT phosphorylation, leading to increased FOXO1 expression and up-regulation of the cell cycle inhibitor p27Kip1 and the proapoptotic molecule BIM. In vivo, LAPTM5 is involved in the elimination of autoreactive B cells and its deficiency exacerbates autoantibody production. Our results reveal a previously unidentified mechanism that contributes to immature B cell apoptosis and B cell tolerance.
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Abstract
Activation-induced cytidine deaminase (AID) initiates somatic hypermutation of immunoglobulin (Ig) gene variable regions and class switch recombination (CSR) of Ig heavy chain constant regions. Two decades of intensive research has greatly expanded our knowledge of how AID functions in peripheral B cells to optimize antibody responses against infections, while maintaining tight regulation of AID to restrain its activity to protect B cell genomic integrity. The many exciting recent advances in the field include: 1) the first description of AID's molecular structure, 2) remarkable advances in high throughput approaches that precisely track AID targeting genome-wide, and 3) the discovery that the cohesion-mediate loop extrusion mechanism [initially discovered in V(D)J recombination studies] also governs AID-medicated CSR. These advances have significantly advanced our understanding of AID's biochemical properties in vitro and AID's function and regulation in vivo. This mini review will discuss these recent discoveries and outline the challenges and questions that remain to be addressed.
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Zhai B, Liu X, Xu Y, Zhu G, Zhou S, He Y, Wang X, Su W, Han G, Wang R. Single-cell atlas of splenocytes reveals a critical role of a novel plasma cell‒specific marker Hspa13 in antibody class-switching recombination and somatic hypermutation. Mol Immunol 2021; 141:79-86. [PMID: 34837777 DOI: 10.1016/j.molimm.2021.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/03/2021] [Accepted: 11/19/2021] [Indexed: 11/15/2022]
Abstract
Our previous study had shown that member 13 (Hspa13) of heat shock protein family A (Hsp70) promotes plasma cell (PC) production and antibody secretion. To further explore Hspa13 expression and function, we combined single-cell RNA-sequencing and antigen receptor lineage (BCR) analysis to characterize sheep red cell‒primed splenocytes. The single-cell transcriptional profiles revealed that Hspa13 is specifically and highly expressed in PCs. These results suggest that Hspa13 is a novel PC-specific marker. In terms of its function, we found that the CD19cre-mediated conditional knock-out (cKO) of Hspa13 reduced the expression of Ebi3 and IL-10 in PCs. Ebi3 and IL-10 are important factors in IL-4‒secreting type 2 helper T cell (Th2) activation and differentiation. As expected, we found that the Hspa13 cKO reduced IL‒4-expressing follicular helper T (Tfh2) cells. Finally, the single-cell antigen receptor analysis demonstrated that the Hspa13 cKO reduced the Aicda-mediated antibody class-switching recombination (CSR) and somatic hypermutation (SHM) in germinal centers (GCs) B cells. Altogether, the single-cell atlas of splenocytes revealed a critical indirect role for the novel PC-specific marker Hspa13 in CSR and SHM in GC B cells by promoting Ebi3 and IL-10 expression in PCs to induce IL-4-expressing Tfh2 cells. Further exploration of Hspa13 expression and function will provide valuable clues for how to use Hspa13 in the treatment of autoimmune diseases.
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Affiliation(s)
- Bing Zhai
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing 100069, China; Department of Geriatric Hematology, Chinese PLA General Hospital, Beijing 100853, China
| | - Xiaoling Liu
- Department of Dermatology, First Medical Centre of Chinese PLA General Hospital, Beijing 100853, China
| | - Yaqi Xu
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing 100069, China
| | - Gaizhi Zhu
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing 100069, China
| | - Shan Zhou
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing 100069, China
| | - Youdi He
- Department of Neurology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China
| | - Xiaoqian Wang
- Staidson (Beijing) Biopharmaceuticals Co., Ltd, Beijing 100176, China
| | - Wenting Su
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing 100069, China.
| | - Gencheng Han
- Beijing Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Renxi Wang
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing 100069, China.
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Regulation of humoral immune response by HIF-1α-dependent metabolic reprogramming of the germinal center reaction. Cell Immunol 2021; 367:104409. [PMID: 34246872 DOI: 10.1016/j.cellimm.2021.104409] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/18/2021] [Accepted: 06/29/2021] [Indexed: 11/23/2022]
Abstract
Hypoxia-inducible factor-1α (HIF-1α) has been implicated in the regulation of many genes responsible for aerobic glycolysis; however, the role of HIF-1α in B-cell metabolism has not been well defined. Here, we analyzed patterns of gene expression and oxygen consumption rates in B-cell subpopulations from humans and mice and described a model of HIF-1α-mediated B-cell metabolic reprogramming during the germinal center (GC) reaction. Importantly, we found that HIF-1α was highly expressed in GC B-cells, and HIF-1α deficiency in B-cells impaired a functional GC reaction, resulting in defective class-switch recombination and generation of high-affinity plasma cells. These results identified an important role of HIF-1α in regulating humoral immunity through metabolic reprogramming during the GC response. This newly discovered metabolic character of GC B-cells will advance our understanding of GC biology and B-cell lymphomagenesis.
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MZB1 promotes the secretion of J-chain-containing dimeric IgA and is critical for the suppression of gut inflammation. Proc Natl Acad Sci U S A 2019; 116:13480-13489. [PMID: 31127044 DOI: 10.1073/pnas.1904204116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
IgA is the most abundantly produced antibody in the body and plays a crucial role in gut homeostasis and mucosal immunity. IgA forms a dimer that covalently associates with the joining (J) chain, which is essential for IgA transport into the mucosa. Here, we demonstrate that the marginal zone B and B-1 cell-specific protein (MZB1) interacts with IgA through the α-heavy-chain tailpiece dependent on the penultimate cysteine residue and prevents the intracellular degradation of α-light-chain complexes. Moreover, MZB1 promotes J-chain binding to IgA and the secretion of dimeric IgA. MZB1-deficient mice are impaired in secreting large amounts of IgA into the gut in response to acute inflammation and develop severe colitis. Oral administration of a monoclonal IgA significantly ameliorated the colitis, accompanied by normalization of the gut microbiota composition. The present study identifies a molecular chaperone that promotes J-chain binding to IgA and reveals an important mechanism that controls the quantity, quality, and function of IgA.
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Hong R, Lai N, Ouchida R, Xiong E, Zhou Y, Min Q, Liu J, Tang Y, Hikida M, Tsubata T, Wang Y, Wang JY. The B cell novel protein 1 (BCNP1) regulates BCR signaling and B cell apoptosis. Eur J Immunol 2019; 49:911-917. [PMID: 30888050 DOI: 10.1002/eji.201847985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/27/2019] [Accepted: 03/14/2019] [Indexed: 01/28/2023]
Abstract
The BCR plays a central role in B cell development, survival, activation, and differentiation. We have identified the B cell novel protein 1 (BCNP1) as a new regulator of BCR signaling. BCNP1 contains a pleckstrin homology domain, three proline-rich motifs, and a potential SH2 binding site, and is predominantly expressed by B cells. We found that BCNP1 overexpression in WEHI231 immature B cells potentiated α-IgM-induced apoptosis. Conversely, BCNP1-deficient WEHI231 cells, generated by CRISPR-Cas9-mediated genome editing, exhibited reduced apoptosis after BCR crosslinking. Biochemical analyses revealed that BCNP1 physically interacted with the B cell linker protein (BLNK), Grb2, and PLCγ2. Moreover, absence of BCNP1 resulted in accelerated dephosphorylation of BLNK, reduced phosphorylation of SYK and PLCγ2, and decreased Ca2+ influx after BCR crosslinking. These results demonstrate that BCNP1 promotes BCR signaling by modulating the phosphorylation of BLNK, SYK, and PLCγ2.
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Affiliation(s)
- Rongjian Hong
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Nannan Lai
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Rika Ouchida
- Division of Mucosal Immunology, the Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Ermeng Xiong
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yang Zhou
- Division of Life Sciences and Medicine, Department of Traditional Chinese Medicine, the First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Qing Min
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Jun Liu
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yue Tang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Masaki Hikida
- Faculty of Engineering Science, Graduate School of Engineering Science, Akita University, Akita, Japan
| | - Takeshi Tsubata
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yanqing Wang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Ji-Yang Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.,Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
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Feng YY, Tang M, Suzuki M, Gunasekara C, Anbe Y, Hiraoka Y, Liu J, Grasberger H, Ohkita M, Matsumura Y, Wang JY, Tsubata T. Essential Role of NADPH Oxidase–Dependent Production of Reactive Oxygen Species in Maintenance of Sustained B Cell Receptor Signaling and B Cell Proliferation. THE JOURNAL OF IMMUNOLOGY 2019; 202:2546-2557. [DOI: 10.4049/jimmunol.1800443] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 02/25/2019] [Indexed: 12/30/2022]
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Lai N, Min Q, Xiong E, Liu J, Zhang L, Yasuda S, Wang JY. A tetrameric form of CD40 ligand with potent biological activities in both mouse and human primary B cells. Mol Immunol 2018; 105:173-180. [PMID: 30529036 DOI: 10.1016/j.molimm.2018.11.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/15/2018] [Accepted: 11/30/2018] [Indexed: 11/19/2022]
Abstract
CD40 ligand (CD40 L) expressed by activated T cells interacts with CD40 on B cells and triggers B cell survival, proliferation and differentiation. Deficiency in CD40 L or CD40 in humans causes hyper IgM syndrome due to a defect in T-B interaction that is essential for Ig gene class switch recombination (CSR). CD40 L belongs to the tumor necrosis factor family and normally forms a homotrimer on the cell surface, which is important for its biological activity. To generate a multimeric CD40 L that can be used to stimulate both mouse and human B cells, we fused the extracellular domain of mouse CD40 L, which is known to also bind human CD40, with streptavidin (SA) that forms a stable tetramer under physiological conditions. As expected, 293 T cells transiently transfected with an SA-CD40 L expression vector secreted tetrameric SA-CD40 L in the culture supernatant. The secreted SA-CD40 L exhibited > 25-fold stronger activities in inducing the survival, activation and proliferation of both mouse and human primary B cells than did an agonistic anti-mouse or anti-human CD40 antibody. In the presence of IL-4, SA-CD40 L also induced efficient CSR and plasma cell differentiation in both mouse and human B cells. Moreover, administration of SA-CD40 L in mice induced activation and proliferation of spleen B cells in vivo. These results demonstrate that the SA-CD40 L fusion protein generated in the present study recapitulates the function of membrane-bound trimeric CD40 L and has potent biological activities in both mouse and human primary B cells.
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Affiliation(s)
- Nannan Lai
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Qing Min
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Ermeng Xiong
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Jun Liu
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Lumin Zhang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Shoya Yasuda
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China; Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, Yokohama, 226-8502, Japan
| | - Ji-Yang Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China.
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