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Block V, Sevdali E, Recher M, Abolhassani H, Hammarstrom L, Smulski CR, Baronio M, Plebani A, Proietti M, Speletas M, Warnatz K, Voll RE, Lougaris V, Schneider P, Eibel H. CVID-Associated B Cell Activating Factor Receptor Variants Change Receptor Oligomerization, Ligand Binding, and Signaling Responses. J Clin Immunol 2023; 43:391-405. [PMID: 36308663 PMCID: PMC9616699 DOI: 10.1007/s10875-022-01378-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 09/23/2022] [Indexed: 02/07/2023]
Abstract
PURPOSE Binding of the B cell activating factor (BAFF) to its receptor (BAFFR) activates in mature B cells many essential pro-survival functions. Null mutations in the BAFFR gene result in complete BAFFR deficiency and cause a block in B cell development at the transition from immature to mature B cells leading therefore to B lymphopenia and hypogammaglobulinemia. In addition to complete BAFFR deficiency, single nucleotide variants encoding BAFFR missense mutations were found in patients suffering from common variable immunodeficiency (CVID), autoimmunity, or B cell lymphomas. As it remained unclear to which extent such variants disturb the activity of BAFFR, we performed genetic association studies and developed a cellular system that allows the unbiased analysis of BAFFR variants regarding oligomerization, signaling, and ectodomain shedding. METHODS In addition to genetic association studies, the BAFFR variants P21R, A52T, G64V, DUP92-95, P146S, and H159Y were expressed by lentiviral gene transfer in DG-75 Burkitt's lymphoma cells and analyzed for their impacts on BAFFR function. RESULTS Binding of BAFF to BAFFR was affected by P21R and A52T. Spontaneous oligomerization of BAFFR was disturbed by P21R, A52T, G64V, and P146S. BAFF-dependent activation of NF-κB2 was reduced by P21R and P146S, while interactions between BAFFR and the B cell antigen receptor component CD79B and AKT phosphorylation were impaired by P21R, A52T, G64V, and DUP92-95. P21R, G64V, and DUP92-95 interfered with phosphorylation of ERK1/2, while BAFF-induced shedding of the BAFFR ectodomain was only impaired by P21R. CONCLUSION Although all variants change BAFFR function and have the potential to contribute as modifiers to the development of primary antibody deficiencies, autoimmunity, and lymphoma, P21R is the only variant that was found to correlate positively with CVID.
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Affiliation(s)
- Violeta Block
- Department of Rheumatology and Clinical Immunology, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center for Chronic Immunodeficiency, Medial Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eirini Sevdali
- Department of Rheumatology and Clinical Immunology, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center for Chronic Immunodeficiency, Medial Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Mike Recher
- Immunodeficiency Clinic and Laboratory, Medical Outpatient Unit and Department Biomedicine, University Hospital and University of Basel, Basel, Switzerland
| | - Hassan Abolhassani
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Lennart Hammarstrom
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Cristian R Smulski
- Department of Rheumatology and Clinical Immunology, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Medical Physics Department, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), San Carlos de Bariloche, Río Negro, Argentina
| | - Manuela Baronio
- Department of Clinical and Exp. Sciences, University of Brescia, Brescia, Italy
| | - Alessandro Plebani
- Department of Clinical and Exp. Sciences, University of Brescia, Brescia, Italy
| | - Michele Proietti
- Center for Chronic Immunodeficiency, Medial Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Institute for Immunodeficiency, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Matthaios Speletas
- Department of Immunology & Histocompatibility, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | - Klaus Warnatz
- Department of Rheumatology and Clinical Immunology, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center for Chronic Immunodeficiency, Medial Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Reinhard E Voll
- Department of Rheumatology and Clinical Immunology, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center for Chronic Immunodeficiency, Medial Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Vassilios Lougaris
- Department of Clinical and Exp. Sciences, University of Brescia, Brescia, Italy
| | - Pascal Schneider
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Hermann Eibel
- Department of Rheumatology and Clinical Immunology, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
- Center for Chronic Immunodeficiency, Medial Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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IgH isotype-specific B cell receptor expression influences B cell fate. Proc Natl Acad Sci U S A 2017; 114:E8411-E8420. [PMID: 28923960 DOI: 10.1073/pnas.1704962114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Ig heavy chain (IgH) isotypes (e.g., IgM, IgG, and IgE) are generated as secreted/soluble antibodies (sIg) or as membrane-bound (mIg) B cell receptors (BCRs) through alternative RNA splicing. IgH isotype dictates soluble antibody function, but how mIg isotype influences B cell behavior is not well defined. We examined IgH isotype-specific BCR function by analyzing naturally switched B cells from wild-type mice, as well as by engineering polyclonal Ighγ1/γ1 and Ighε/ε mice, which initially produce IgG1 or IgE from their respective native genomic configurations. We found that B cells from wild-type mice, as well as Ighγ1/γ1 and Ighε/ε mice, produce transcripts that generate IgM, IgG1, and IgE in an alternative splice form bias hierarchy, regardless of cell stage. In this regard, we found that mIgμ > mIgγ1 > mIgε, and that these BCR expression differences influence respective developmental fitness. Restrained B cell development from Ighγ1/γ1 and Ighε/ε mice was proportional to sIg/mIg ratios and was rescued by enforced expression of the respective mIgs. In addition, artificially enhancing BCR signal strength permitted IgE+ memory B cells-which essentially do not exist under normal conditions-to provide long-lived memory function, suggesting that quantitative BCR signal weakness contributes to restraint of IgE B cell responses. Our results indicate that IgH isotype-specific mIg/BCR dosage may play a larger role in B cell fate than previously anticipated.
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Finnegan A, Ashaye S, Hamel KM. B effector cells in rheumatoid arthritis and experimental arthritis. Autoimmunity 2012; 45:353-63. [PMID: 22432771 DOI: 10.3109/08916934.2012.665526] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Rheumatoid arthritis is a chronic autoimmune immune disease affecting approximately 1% of the population. There has been a renewed interest in the role of B cells in rheumatoid arthritis based on the evidence that B cell depletion therapy is effective in the treatment of disease. This review summarizes the current knowledge of the mechanisms by which B cells contribute to autoimmune arthritis including roles as autoantibody producing cells, antigen-presenting cells, cytokine producing cells, and regulatory cells.
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Affiliation(s)
- Alison Finnegan
- Department of Medicine, Section of Rheumatology, Rush University Medical Center, Chicago, Illinois 60612, USA.
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Abstract
The development of an adaptive immune system based on the random generation of antigen receptors requires a stringent selection process that sifts through receptor specificities to remove those reacting with self-antigens. In the B-cell lineage, this selection process is first applied to IgM(+) immature B cells. By using increasingly sophisticated mouse models, investigators have identified the central tolerance mechanisms that negatively select autoreactive immature B cells and prevent inclusion of their antigen receptors into the peripheral B-cell pool. Additional studies have uncovered mechanisms that promote the differentiation of nonautoreactive immature B cells and their positive selection into the peripheral B-cell population. These mechanisms of central selection are fundamental to the generation of a naïve B-cell repertoire that is largely devoid of self-reactivity while capable of reacting with any foreign insult.
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Affiliation(s)
- Roberta Pelanda
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver School of Medicine, Denver, Colorado 80206, USA.
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Dylke J, Lopes J, Dang-Lawson M, Machtaler S, Matsuuchi L. Role of the extracellular and transmembrane domain of Ig-alpha/beta in assembly of the B cell antigen receptor (BCR). Immunol Lett 2007; 112:47-57. [PMID: 17675166 DOI: 10.1016/j.imlet.2007.06.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 06/26/2007] [Accepted: 06/27/2007] [Indexed: 01/27/2023]
Abstract
The B cell antigen receptor (BCR) is expressed on the surface of B-lymphocytes where it binds antigen and transmits signals that regulate B cell activation, growth and differentiation. The BCR is composed of membrane IgM (mIgM) and two signaling proteins, Ig-alpha and Ig-beta. If either of the signaling proteins is not expressed, the incomplete mIgM-containing BCR will not traffic to the cell surface. Our hypothesis is that specific protein:protein interactions between both the extracellular and transmembrane (TM) regions of Ig-alpha and Ig-beta are necessary for receptor assembly, cell surface expression and effective signaling to support the proper development of B cells. While previous work has shown the importance of the TM region in BCR assembly, this study indicates that a heterodimer of the extracellular domains of Ig-alpha and Ig-beta are also required for proper association with mIgM. Cell lines expressing mutated Ig-alpha proteins that did not heterodimerize with Ig-beta in the extracellular and TM domains were unable to properly assemble the BCR. Conversely, an Ig-alpha mutant with an Ig-beta cytoplasmic tail (Cbeta (alpha/alpha/beta)) was able to assemble with the rest of the BCR, in particular with Ig-beta, and traffic to the cell surface. Thus, both the extracellular and TM regions of the Ig-alpha/Ig-beta must be properly associated in order for the BCR to assemble.
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Affiliation(s)
- Janis Dylke
- Cell Biology Group, Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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Fuentes-Pananá EM, Bannish G, Karnell FG, Treml JF, Monroe JG. Analysis of the Individual Contributions of Igα (CD79a)- and Igβ (CD79b)-Mediated Tonic Signaling for Bone Marrow B Cell Development and Peripheral B Cell Maturation. THE JOURNAL OF IMMUNOLOGY 2006; 177:7913-22. [PMID: 17114463 DOI: 10.4049/jimmunol.177.11.7913] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The individual contribution of Igalpha and Igbeta for BCR-triggered fates is unclear. Prior evidence supports conflicting ideas concerning unique as well as redundant functions for these proteins in the context of BCR/pre-BCR signaling. Part of this ambiguity may reflect the recent appreciation that Igalpha and Igbeta participate in both Ag-independent (tonic) and Ag-dependent signaling. The present study undertook defining the individual requirement for Igalpha and Igbeta under conditions where only ligand-independent tonic signaling was operative. In this regard, we have constructed chimeric proteins containing one or two copies of the cytoplasmic domains of either Igalpha or Igbeta and Igalpha/Igbeta heterodimers with targeted Tyr-->Phe modifications. The ability of these proteins to act as surrogate receptors and trigger early bone marrow and peripheral B cell maturation was tested in RAG2(-/-) primary pro-B cell lines and in gene transfer experiments in the muMT mouse model. We considered that the threshold for a functional activity mediated by the pre-BCR/BCR might only be reached when two functional copies of the Igalpha/Igbeta ITAM domain are expressed together, and therefore the specificity conferred by these proteins can only be observed in these conditions. We found that the ligand-independent tonic signal is sufficient to drive development into mature follicular B cells and both Igalpha and Igbeta chains supported formation of this population. In contrast, neither marginal zone nor B1 mature B cell subsets develop from bone marrow precursors under conditions where only tonic signals are generated.
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Affiliation(s)
- Ezequiel M Fuentes-Pananá
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Weiler CR, Bankers-Fulbright JL. Common variable immunodeficiency: test indications and interpretations. Mayo Clin Proc 2005; 80:1187-200. [PMID: 16178499 DOI: 10.4065/80.9.1187] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder that can present with multiple phenotypes, all of which are characterized by hypogammaglobulinemia, in a person at any age. A specific genetic defect that accounts for all CVID phenotypes has not been identified, and it is likely that several distinct genetic disorders with similar clinical presentations are responsible for the observed variation. In this review, we summarize the known genetic mutations that give rise to hypogammaglobulinemia and how these gene products affect normal or abnormal B-cell development and function, with particular emphasis on CVID. Additionally, we describe specific phenotypic and genetic laboratory tests that can be used to diagnose CVID and provide guidelines for test interpretation and subsequent therapeutic intervention.
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Affiliation(s)
- Catherine R Weiler
- Department of Internal Medicine and Division of Allergic Diseases, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Liu X, Manser T. Antinuclear antigen B cells that down-regulate surface B cell receptor during development to mature, follicular phenotype do not display features of anergy in vitro. THE JOURNAL OF IMMUNOLOGY 2005; 174:4505-15. [PMID: 15814671 DOI: 10.4049/jimmunol.174.8.4505] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We previously demonstrated that B cells expressing a transgenic BCR with "dual reactivity" for the hapten arsonate and nuclear autoantigens efficiently complete development to follicular phenotype and stably reside in follicles in vivo. These B cells express very low levels of surface IgM and IgD, suggesting that they avoid central deletion and peripheral anergy by reducing their avidity for autoantigen via surface BCR (sBCR) down-regulation. Since a variety of states of B cell anergy have been previously described, a thorough examination of the functional capabilities of these B cells was required to test this hypothesis. In this study, we show that surface Ig cross-linking induces amounts of proximal BCR signaling in these B cells commensurate with their reduced sBCR levels. Functionally, however, they are comparable to nonautoreactive B cells in cell cycle progression, up-regulation of activation and costimulatory molecules, and Ab-forming cell differentiation when treated with a variety of stimuli in vitro. In addition, these B cells can efficiently process and present Ag and are capable of undergoing cognate interaction with naive TCR-transgenic T cells, resulting in robust IL-2 production. Together, these data reveal a lack of intrinsic anergy involving any known mechanism, supporting the idea that this type of antinuclear Ag B cell becomes indifferent to cognate autoantigen by down-regulating sBCR.
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MESH Headings
- Animals
- Antibody-Producing Cells/cytology
- Antibody-Producing Cells/immunology
- Antigen Presentation
- Autoantigens/metabolism
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/immunology
- Cell Cycle
- Cell Differentiation
- Cell Nucleus/immunology
- Clonal Anergy
- Down-Regulation
- Hybridomas/immunology
- In Vitro Techniques
- Lymphocyte Activation
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mutation
- Phenotype
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
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Affiliation(s)
- Xiaohe Liu
- Department of Microbiology and Immunology and Kimmel Cancer Center, Jefferson Medical College, Philadelphia, PA 19017-5541, USA
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Edry E, Melamed D. Receptor editing in positive and negative selection of B lymphopoiesis. THE JOURNAL OF IMMUNOLOGY 2004; 173:4265-71. [PMID: 15383554 DOI: 10.4049/jimmunol.173.7.4265] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In B lymphopoiesis, Ag receptor expression and signaling are critical to determine developmental progression, survival, and activation. Several positive and negative selection checkpoints to test this receptor have been described in B lymphopoiesis, aiming to ensure the generation of functionally competent, nonautoimmune repertoire. Secondary Ag receptor gene recombination allows B lymphocytes to replace an inappropriate receptor with a new receptor, a mechanism called receptor editing. This salvage mechanism uncouples the Ag receptor fate from that of the cell itself, suggesting that B cell repertoire is regulated by a process of receptor selection. Secondary rearrangements are stimulated in different stages of B cell development, where editing of the receptor is necessary to fulfill stage-specific requirements. In this study, we discuss the contribution of receptor editing in B lymphopoiesis and its regulation by positive and negative selection signals.
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Affiliation(s)
- Efrat Edry
- Department of Immunology, Faculty of Medicine, Technion, Israel
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