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Kubagawa H, Mahmoudi Aliabadi P, Al-Qaisi K, Jani PK, Honjo K, Izui S, Radbruch A, Melchers F. Functions of IgM fc receptor (FcµR) related to autoimmunity. Autoimmunity 2024; 57:2323563. [PMID: 38465789 DOI: 10.1080/08916934.2024.2323563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 02/20/2024] [Indexed: 03/12/2024]
Abstract
Unlike Fc receptors for switched immunoglobulin (Ig) isotypes, Fc receptor for IgM (FcµR) is selectively expressed by lymphocytes. The ablation of the FcµR gene in mice impairs B cell tolerance as evidenced by concomitant production of autoantibodies of IgM and IgG isotypes. In this essay, we reiterate the autoimmune phenotypes observed in mutant mice, ie IgM homeostasis, dysregulated humoral immune responses including autoantibodies, and Mott cell formation. We also propose the potential phenotypes in individuals with FCMR deficiency and the model for FcµR-mediated regulation of self-reactive B cells.
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Affiliation(s)
| | | | | | - Peter K Jani
- Deutsches Rheuma-Forschungszentrum Berlin, Berlin, Germany
| | - Kazuhito Honjo
- Department of Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shozo Izui
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | | | - Fritz Melchers
- Deutsches Rheuma-Forschungszentrum Berlin, Berlin, Germany
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2
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Fei X, Li JF, Fang YD, Liu LP, Liu KJ, Zeng WW, Wang WH. Distribution characteristics of FcμR positive cells in small intestinal lymph nodes of Bactrian camel. PLoS One 2023; 18:e0287329. [PMID: 37471384 PMCID: PMC10358951 DOI: 10.1371/journal.pone.0287329] [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: 02/16/2023] [Accepted: 06/02/2023] [Indexed: 07/22/2023] Open
Abstract
Exploring the expression characteristics of FcμR in small intestinal lymph nodes of bactrian camels can lay the foundation for further revealing the function of FcμR. The FcμR expression characteristics were systematically analysed by using prokaryotic expression, antibody preparation, immunohistochemical staining and statistical analysis. FcμR positive cells were mainly located in the lymphoid follicles and their numbers decreased in the order of duodenal lymph nodes, jejunal lymph nodes and ileal lymph nodes, and the number of positive cells was statistically significant between different intestinal segments (P<0.05). The FcμR is expressed in lymphoid follicular B cells, which not only facilitates the body's ability to regulate secretory IgM levels, but also acts as a local immune defence barrier. The small intestine has dual functions of immune tolerance and immune response, the proximal part mainly focuses on immune tolerance, and the distal part mainly focuses on immune response. This distribution ensures the unity of the duodenal absorption and immune defence, and also significantly increases the efficiency of the entire small intestine, which is why the number of FcμR positive cells decreases in the order of duodenal lymph nodes, jejunal lymph nodes and ileal lymph nodes.
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Affiliation(s)
- Xie Fei
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Jian fei Li
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Ying dong Fang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Li ping Liu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Ke Jiang Liu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Wei wei Zeng
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Wen hui Wang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
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3
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Mahmoudi Aliabadi P, Al-Qaisi K, Jani PK, Honjo K, Klemm U, Lee KH, Baumgarth N, Radbruch A, Melchers F, Kubagawa H. Enhanced Mott cell formation linked with IgM Fc receptor (FcμR) deficiency. Eur J Immunol 2023; 53:e2250315. [PMID: 37098762 DOI: 10.1002/eji.202250315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 03/31/2023] [Accepted: 04/25/2023] [Indexed: 04/27/2023]
Abstract
In previous studies, Mott cells, an unusual form of plasma cells containing Ig-inclusion bodies, were frequently observed in peripheral lymphoid tissues in our IgM Fc receptor (FcμR)-deficient (KO) mouse strain. Because of discrepancies in the reported phenotypes of different Fcmr KO mouse strains, we here examined two additional available mutant strains and confirmed that such enhanced Mott-cell formation was a general phenomenon associated with FcμR deficiency. Splenic B cells from Fcmr KO mice clearly generated more Mott cells than those from WT mice when stimulated in vitro with LPS alone or a B-1, but not B-2, activation cocktail. Nucleotide sequence analysis of the Ig variable regions of a single IgMλ+ Mott-hybridoma clone developed from splenic B-1 B cells of Fcmr KO mice revealed the near (VH) or complete (Vλ) identity with the corresponding germline gene segments and the addition of six or five nucleotides at the VH/DH and DH/JH junctions, respectively. Transduction of an FcμR cDNA into the Mott hybridoma significantly reduced cells containing IgM-inclusion bodies with a concomitant increase in IgM secretion, leading to secreted IgM binding to FcμR expressed on Mott transductants. These findings suggest a regulatory role of FcμR in the formation of Mott cells and IgM-inclusion bodies.
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Affiliation(s)
| | - Khlowd Al-Qaisi
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum (DRFZ), Berlin, Germany
| | - Peter K Jani
- Lymphocyte Development, Deutsches Rheuma-Forschungszentrum (DRFZ), Berlin, Germany
| | - Kazuhito Honjo
- Department of Medicine, School of Medicine, University of Alabama, Birmingham, USA
| | - Uwe Klemm
- Experimental Animals, Max Planck Institute for Infectious Biology, Berlin, Germany
| | - Kyeong-Hee Lee
- Inflammation Research Group, Institute of Clinical Chemistry, Hannover Medical School, Hanover, Germany
| | - Nicole Baumgarth
- Department of Molecular Microbiology and immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
| | - Andreas Radbruch
- Department of Cell Biology, Deutsches Rheuma-Forschungszentrum, DRFZ), Berlin, Germany
| | - Fritz Melchers
- Lymphocyte Development, Deutsches Rheuma-Forschungszentrum (DRFZ), Berlin, Germany
| | - Hiromi Kubagawa
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum (DRFZ), Berlin, Germany
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4
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Kubagawa H, Clark C, Skopnik CM, Mahmoudi Aliabadi P, Al-Qaisi K, Teuber R, Jani PK, Radbruch A, Melchers F, Engels N, Wienands J. Physiological and Pathophysiological Roles of IgM Fc Receptor (FcµR) Isoforms. Int J Mol Sci 2023; 24:ijms24065728. [PMID: 36982860 PMCID: PMC10058298 DOI: 10.3390/ijms24065728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/14/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
IgM is the first antibody to emerge during phylogeny, ontogeny, and immune responses and serves as a first line of defense. Effector proteins interacting with the Fc portion of IgM, such as complement and its receptors, have been extensively studied for their functions. IgM Fc receptor (FcµR), identified in 2009, is the newest member of the FcR family and is intriguingly expressed by lymphocytes only, suggesting the existence of distinct functions as compared to the FcRs for switched Ig isotypes, which are expressed by various immune and non-hematopoietic cells as central mediators of antibody-triggered responses by coupling the adaptive and innate immune responses. Results from FcµR-deficient mice suggest a regulatory function of FcµR in B cell tolerance, as evidenced by their propensity to produce autoantibodies of both IgM and IgG isotypes. In this article, we discuss conflicting views about the cellular distribution and potential functions of FcµR. The signaling function of the Ig-tail tyrosine-like motif in the FcµR cytoplasmic domain is now formally shown by substitutional experiments with the IgG2 B cell receptor. The potential adaptor protein associating with FcµR and the potential cleavage of its C-terminal cytoplasmic tail after IgM binding are still enigmatic. Critical amino acid residues in the Ig-like domain of FcµR for interacting with the IgM Cµ4 domain and the mode of interaction are now defined by crystallographic and cryo-electron microscopic analyses. Some discrepancies on these interactions are discussed. Finally, elevated levels of a soluble FcµR isoform in serum samples are described as the consequence of persistent B cell receptor stimulation, as seen in chronic lymphocytic leukemia and probably in antibody-mediated autoimmune disorders.
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Affiliation(s)
| | - Caren Clark
- Institute of Cellular & Molecular Immunology, University Medical Center, 37073 Göttingen, Germany
| | | | | | | | - Ruth Teuber
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany
| | - Peter K Jani
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany
| | | | - Fritz Melchers
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany
| | - Niklas Engels
- Institute of Cellular & Molecular Immunology, University Medical Center, 37073 Göttingen, Germany
| | - Jürgen Wienands
- Institute of Cellular & Molecular Immunology, University Medical Center, 37073 Göttingen, Germany
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5
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Mahmoudi Aliabadi P, Teuber R, Jani PK, Wilson L, Enghard P, Barnes S, Chiorazzi N, Radbruch A, Melchers F, Kubagawa H. Soluble Fc Receptor for IgM in Sera From Subsets of Patients With Chronic Lymphocytic Leukemia as Determined by a New Mouse Monoclonal Antibody. Front Immunol 2022; 13:863895. [PMID: 35784336 PMCID: PMC9245419 DOI: 10.3389/fimmu.2022.863895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 05/06/2022] [Indexed: 11/15/2022] Open
Abstract
The FcR for IgM (FcµR) is the newest member of the FcR family, selectively expressed by lymphocytes, and distinct from FcRs for switched Ig isotypes that are expressed by various immune cell types and non-hematopoietic cells. From studies of Fcmr-ablated mice, FcµR was shown to have a regulatory function in B-cell tolerance, as evidenced by high serum titers of autoantibodies of the IgM and IgG isotypes in mutant mice. In our previous studies, both cell-surface and serum FcµR levels were elevated in patients with chronic lymphocytic leukemia (CLL), where antigen-independent self-ligation of BCR is a hallmark of the neoplastic B cells. This was assessed by sandwich ELISA using two different ectodomain-specific mAbs. To determine whether the serum FcµR is derived from cleavage of its cell-surface receptor (shedding) or its alternative splicing to skip the transmembrane exon resulting in a 70-aa unique hydrophilic C-terminus (soluble), we developed a new mouse IgG1κ mAb specific for human soluble FcμR (solFcμR) by taking advantages of the unique nature of transductant stably producing His-tagged solFcµR and of an in vivo differential immunization. His-tagged solFcμR attached to exosomes and plasma membranes, allowing immunization and initial hybridoma screening without purification of solFcμR. Differential immunization with tolerogen (membrane FcμR) and immunogen (solFcμR) also facilitated to generate solFcμR-specific hybridomas. The resultant solFcμR-specific mAb reacted with serum FcµR in subsets of CLL patients. This mAb, along with another ectodomain-specific mAb, will be used for verifying the hypothesis that the production of solFcµR is the consequence of chronic stimulation of BCR.
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Affiliation(s)
| | - Ruth Teuber
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
| | - Peter K. Jani
- Lymphocyte Development, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
| | - Landon Wilson
- Targeted Metabolomics and Proteomics Laboratory, Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Philipp Enghard
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin, Berlin, Germany
| | - Stephen Barnes
- Targeted Metabolomics and Proteomics Laboratory, Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Nicholas Chiorazzi
- Karches Center for Oncology Research, Feinstein Institute for Medical Research, Manhasset, NY, United States
| | - Andreas Radbruch
- Cell Biology, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
| | - Fritz Melchers
- Lymphocyte Development, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
| | - Hiromi Kubagawa
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
- *Correspondence: Hiromi Kubagawa,
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Hiepe F, Alexander T, Dörner T, Hauser AE, Hoyer BF, Kubagawa H, Skriner K, Tokoyoda K. [B lymphocytes and plasma cells as drivers of rheumatic diseases]. Z Rheumatol 2022; 81:660-666. [PMID: 35380249 PMCID: PMC8980791 DOI: 10.1007/s00393-022-01189-2] [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] [Accepted: 02/11/2022] [Indexed: 11/21/2022]
Abstract
Verschiedene Arbeitsgruppen am Deutschen Rheuma-Forschungszentrum Berlin haben in enger Zusammenarbeit mit der Medizinischen Klinik mit Schwerpunkt Rheumatologie und Klinische Immunologie an der Charité wichtige Beiträge zur Bedeutung der B‑Zellen und Plasmazellen bei rheumatischen Erkrankungen geleistet, die nicht nur für die Rheumatologie, sondern für alle klinischen Fachgebiete, in denen antikörpervermittelte Erkrankungen eine Rolle spielen, relevant sind. Insbesondere wird auf die gestörte B‑Zell-Homöostase, die Bedeutung des Immunglobulin M(IgM)-Fc-Rezeptors für die Regulation der Autoimmunität, die Rolle der langlebigen Gedächtnis-Plasmazelle bei der Aufrechterhaltung der Autoimmunität sowie die Sicherung ihres Überlebens in speziellen, von Stromazellen organisierten Nischen im Knochenmark und in entzündeten Geweben eingegangen. Die Forschungsergebnisse haben zu einem besseren Verständnis der immunologischen und molekularen Mechanismen bei rheumatischen Erkrankungen und ihrer Therapie beigetragen. Die Identifizierung der langlebigen Gedächtnis-Plasmazelle hat zu vielversprechenden therapeutischen Ansätzen mit kurativem Potenzial bei Autoimmunerkrankungen geführt.
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Affiliation(s)
- Falk Hiepe
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland. .,Medizinische Klinik mit Schwerpunkt Rheumatologie u. Klinische Immunologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and, Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland.
| | - Tobias Alexander
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland.,Medizinische Klinik mit Schwerpunkt Rheumatologie u. Klinische Immunologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and, Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland
| | - Thomas Dörner
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland.,Medizinische Klinik mit Schwerpunkt Rheumatologie u. Klinische Immunologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and, Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland
| | - Anja E Hauser
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland.,Medizinische Klinik mit Schwerpunkt Rheumatologie u. Klinische Immunologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and, Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland
| | - Bimba F Hoyer
- Klinik für Innere Medizin I, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Deutschland
| | - Hiromi Kubagawa
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland
| | - Karl Skriner
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland.,Medizinische Klinik mit Schwerpunkt Rheumatologie u. Klinische Immunologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and, Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland
| | - Koji Tokoyoda
- Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Deutschland
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7
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Skopnik CM, Al-Qaisi K, Calvert RA, Enghard P, Radbruch A, Sutton BJ, Kubagawa H. Identification of Amino Acid Residues in Human IgM Fc Receptor (FcµR) Critical for IgM Binding. Front Immunol 2021; 11:618327. [PMID: 33584711 PMCID: PMC7873564 DOI: 10.3389/fimmu.2020.618327] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/03/2020] [Indexed: 11/17/2022] Open
Abstract
Both non-immune “natural” and antigen-induced “immune” IgM are important for protection against infections and for regulation of immune responses to self-antigens. The roles of its Fc receptor (FcµR) in these IgM effector functions have begun to be explored. In the present study, by taking advantage of the difference in IgM-ligand binding of FcµRs of human (constitutive binding) and mouse (transient binding), we replaced non-conserved amino acid residues of human FcµR with mouse equivalents before establishment of cell lines stably expressing mutant or wild-type (WT) receptors. The resultant eight-different mutant FcµR-bearing cells were compared with WT receptor-bearing cells for cell-surface expression and IgM-binding by flow cytometric assessments using receptor-specific mAbs and IgM paraproteins as ligands. Three sites Asn66, Lys79-Arg83, and Asn109, which are likely in the CDR2, DE loop and CDR3 of the human FcµR Ig-like domain, respectively, were responsible for constitutive IgM binding. Intriguingly, substitution of Glu41 and Met42 in the presumed CDR1 with the corresponding mouse residues Gln and Leu, either single or more prominently in combination, enhanced both the receptor expression and IgM binding. A four-aa stretch of Lys24-Gly27 in the predicted A ß-strand of human FcµR appeared to be essential for maintenance of its proper receptor conformation on plasma membranes because of reduction of both receptor expression and IgM-binding potential when these were mutated. Results from a computational structural modeling analysis were consistent with these mutational data and identified a possible mode of binding of FcµR with IgM involving the loops including Asn66, Arg83 and Asn109 of FcµR interacting principally with the Cµ4 domain including Gln510 and to a lesser extent Cµ3 domain including Glu398, of human IgM. To our knowledge, this is the first experimental report describing the identification of amino acid residues of human FcµR critical for binding to IgM Fc.
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Affiliation(s)
| | - Khlowd Al-Qaisi
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
| | - Rosaleen A Calvert
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Philipp Enghard
- Department of Nephrology and Medical Intensive Care, Charité-Universitätmedizin, Berlin, Germany
| | - Andreas Radbruch
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
| | - Brian J Sutton
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Hiromi Kubagawa
- Humoral Immune Regulation, Deutsches Rheuma-Forschungszentrum, Berlin, Germany
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Singh VK, Kumar S, Dhaked RK, Ansari AS, Lohiya NK, Tapryal S. Generation of oligomers of subunit vaccine candidate glycoprotein D of Herpes Simplex Virus-2 expressed in fusion with IgM Fc domain(s) in Escherichia coli: A strategy to enhance the immunogenicity of the antigen. 3 Biotech 2020; 10:463. [PMID: 33047090 PMCID: PMC7541101 DOI: 10.1007/s13205-020-02452-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/23/2020] [Indexed: 11/25/2022] Open
Abstract
Glycoprotein D (gD) of Herpes Simplex Virus-2 is used as an antigen in various anti-herpes subunit vaccines owing to its involvement in binding the host cell receptors for host infectivity. However, most of these monomeric protein based candidates have shown low immunogenicity in animal models. To enhance the immunogenicity of gD, a fresh approach of fusing its ectodomain with the Fc domain(s) of IgM has been adopted to oligomerize the viral antigen and to exploite the immune-modulating potential of IgM Fc. Six vaccine constructs, generated by fusing three gD-ectodomain-length-variants with the Ig µ-chain domain 4 (µCH4) and µCH3-CH4 fragment, were cloned in Escherichia coli using pET28b( +) vector. The vaccine proteins were expressed in the form of inclusion bodies (IBs) and were in vitro refolded into protein oligomers of high stoichiometries of ~ 15–24, with 70–80% refolding yields. The conformations of gD and Fc components of the refolded oligomers were analyzed by ELISA and CD spectroscopy and were found to be native-like. The sizes and profiles of the size-distribution of oligomers were determined by dynamic light scattering (DLS). The candidate C2 (gD-μCH3-CH4), showing the most compact oligomer size and uniform distribution of its particles was chosen as the suitable candidate for mice immunization studies to assess the immunogenicity of the antigen gD. The C2 oligomer stimulated a strong anti-gD humoral response with an antibody titer of 102,400 and a strong, biased Th1 immune response in C57BL/6 mice, indicating its potential as a strong immunogen which may serve as an effective vaccine candidate.
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Affiliation(s)
- Vikas Kumar Singh
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandar Sindri, Ajmer, Rajasthan India 305817
| | - Sandeep Kumar
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandar Sindri, Ajmer, Rajasthan India 305817
| | - Rajeev Kumar Dhaked
- Department of Zoology, Center for Advanced Studies, University of Rajasthan, Jaipur, Rajasthan India 302004
| | - Abdul S. Ansari
- Department of Zoology, Center for Advanced Studies, University of Rajasthan, Jaipur, Rajasthan India 302004
| | - Nirmal K. Lohiya
- Indian Society for the Study of Reproduction and Fertility, Department of Zoology, Center for Advanced Studies, University of Rajasthan, Jaipur, Rajasthan India 302004
| | - Suman Tapryal
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandar Sindri, Ajmer, Rajasthan India 305817
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Keyt BA, Baliga R, Sinclair AM, Carroll SF, Peterson MS. Structure, Function, and Therapeutic Use of IgM Antibodies. Antibodies (Basel) 2020; 9:E53. [PMID: 33066119 PMCID: PMC7709107 DOI: 10.3390/antib9040053] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 10/09/2020] [Indexed: 12/18/2022] Open
Abstract
Natural immunoglobulin M (IgM) antibodies are pentameric or hexameric macro-immunoglobulins and have been highly conserved during evolution. IgMs are initially expressed during B cell ontogeny and are the first antibodies secreted following exposure to foreign antigens. The IgM multimer has either 10 (pentamer) or 12 (hexamer) antigen binding domains consisting of paired µ heavy chains with four constant domains, each with a single variable domain, paired with a corresponding light chain. Although the antigen binding affinities of natural IgM antibodies are typically lower than IgG, their polyvalency allows for high avidity binding and efficient engagement of complement to induce complement-dependent cell lysis. The high avidity of IgM antibodies renders them particularly efficient at binding antigens present at low levels, and non-protein antigens, for example, carbohydrates or lipids present on microbial surfaces. Pentameric IgM antibodies also contain a joining (J) chain that stabilizes the pentameric structure and enables binding to several receptors. One such receptor, the polymeric immunoglobulin receptor (pIgR), is responsible for transcytosis from the vasculature to the mucosal surfaces of the lung and gastrointestinal tract. Several naturally occurring IgM antibodies have been explored as therapeutics in clinical trials, and a new class of molecules, engineered IgM antibodies with enhanced binding and/or additional functional properties are being evaluated in humans. Here, we review the considerable progress that has been made regarding the understanding of biology, structure, function, manufacturing, and therapeutic potential of IgM antibodies since their discovery more than 80 years ago.
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Affiliation(s)
- Bruce A. Keyt
- IGM Biosciences Inc, 325 East Middlefield Road, Mountain View, CA 94043, USA; (R.B.); (A.M.S.); (S.F.C.); (M.S.P.)
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10
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Kumar S, Singh VK, Vasam M, Patil PS, Dhaked RK, Ansari AS, Lohiya NK, Parashar D, Tapryal S. An in vitro refolding method to produce oligomers of anti-CHIKV, E2-IgM Fc fusion subunit vaccine candidates expressed in E. coli. J Immunol Methods 2020; 487:112869. [PMID: 32971119 DOI: 10.1016/j.jim.2020.112869] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 09/12/2020] [Accepted: 09/16/2020] [Indexed: 12/25/2022]
Abstract
Recombinant envelope protein-1 (E1) and E2 of Chikungunya virus (CHIKV) has been shown to elicit neutralizing antibodies and a balanced Th1/Th2 response in mice however with limited protection. Recently reported CHIK virus-like particles showed augmented immunity and protection in adult mice in comparison to E1 and E2, however exacerbated the disease in aged subjects. In order to improve the overall efficacy of protein based vaccines, novel strategies need to be adopted. The discovery of IgM Fc receptor (FcμR) and its role in humoral immune response led us to hypothesise that fusion of an antigen with Fc of IgM may enhance its immunogenicity by polymerizing it and FcμR mediated activation of B and other immune cells. We report in the current study, expression of E2 subunit of CHIKV in fusion with various IgM Fc domains/peptides in E. coli, their in-vitro refolding, characterization and immune response in C57BL/6 mice. Candidates fused with CH3-CH4 Fc fragment produced stable oligomers, whereas the one fused with peptides remained monomeric. The latter elicited a strong humoral and a balanced Th1/Th2 response in mice, whereas the polymeric candidate despite eliciting a strong humoral response, stimulated a biased Th1 response and exhibited higher virus neutralization in Vero cells.
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Affiliation(s)
- Sandeep Kumar
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Vikas Kumar Singh
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Manohar Vasam
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Poonam Shewale Patil
- Dengue & Chikungunya Group, ICMR-National Institute of Virology, 20-A Dr. Ambedkar Road, Pune 411001, India
| | - Rajeev K Dhaked
- Department of Zoology, Centre for Advanced Studies, University of Rajasthan, JLN Marg, Jaipur, Rajasthan 302004, India
| | - Abdul S Ansari
- Department of Zoology, Centre for Advanced Studies, University of Rajasthan, JLN Marg, Jaipur, Rajasthan 302004, India
| | - Nirmal K Lohiya
- Department of Zoology, Centre for Advanced Studies, Indian Society for the Study of Reproduction & Fertility, University of Rajasthan, Jaipur, Rajasthan 302004, India
| | - Deepti Parashar
- Dengue & Chikungunya Group, ICMR-National Institute of Virology, 20-A Dr. Ambedkar Road, Pune 411001, India
| | - Suman Tapryal
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India.
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11
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Jani PK, Kubagawa H, Melchers F. A rheostat sets B-cell receptor repertoire selection to distinguish self from non-self. Curr Opin Immunol 2020; 67:42-49. [PMID: 32916645 DOI: 10.1016/j.coi.2020.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 12/21/2022]
Abstract
In bone marrow VDJ-recombination continuously generates original repertoires of immature B cells expressing IgM-B cell receptor (BcR), in which each cell recognizes the wide variety of self and non-self antigens with an individually different spectrum of avidities. High avidity self-reactive B cells try to edit their BcRs by secondary or multiple VL-rearrangements to JL-rearrangements. If they do not manage to change their self reactivity, they are deleted by apoptosis. Low avidity self-reactive B cells are anergized, while B cells with no avidity to self are ignored. A rheostat crosslinking antigen-binding BcRs, self antigen complexed with pentameric IgM and Fcμ-receptor monitors high, low or no binding. PI3K and PTEN are the effectors of this self antigen-sensing device. In mature B cells this rheostat continues to function in the activation of resting B cells by foreign antigens which crosslink BcR, antigen and pentameric IgM with Fcμ-receptors.
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Affiliation(s)
- Peter K Jani
- Deutsches Rheuma-Forschungszentrum, Charitéplatz 1, D-10117 Berlin, Germany.
| | - Hiromi Kubagawa
- Deutsches Rheuma-Forschungszentrum, Charitéplatz 1, D-10117 Berlin, Germany
| | - Fritz Melchers
- Deutsches Rheuma-Forschungszentrum, Charitéplatz 1, D-10117 Berlin, Germany
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12
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Gong S, Ruprecht RM. Immunoglobulin M: An Ancient Antiviral Weapon - Rediscovered. Front Immunol 2020; 11:1943. [PMID: 32849652 PMCID: PMC7432194 DOI: 10.3389/fimmu.2020.01943] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/20/2020] [Indexed: 12/30/2022] Open
Abstract
Recent discoveries have shed new light onto immunoglobulin M (IgM), an ancient antibody class preserved throughout evolution in all vertebrates. First, IgM – long thought to be a perfect pentamer – was shown to be asymmetric, resembling a quasi-hexamer missing one monomer and containing a gap. Second, this gap allows IgM to serve as carrier of a specific host protein, apoptosis inhibitor of macrophages (AIM), which is released to promote removal of dead-cell debris, cancer cells, or pathogens. Third, recombinant IgM delivered mucosally by passive immunization gave proof-of-concept that this antibody class can prevent mucosal simian-human immunodeficiency virus transmission in non-human primates. Finally, IgM’s role in adaptive immunity goes beyond being only a first defender to respond to pathogen invasion, as long-lived IgM plasma cells have been observed predominantly residing in the spleen. In fact, IgM produced by such cells contained somatic hypermutations and was linked to protection against lethal influenza virus challenge in murine models. Importantly, such long-lived IgM plasma cells had been induced by immunization 1 year before challenge. Together, new data on IgM function raise the possibility that vaccine strategies aimed at preventing virus acquisition could include this ancient weapon.
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Affiliation(s)
- Siqi Gong
- New Iberia Research Center, University of Louisiana at Lafayette, New Iberia, LA, United States.,Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Ruth M Ruprecht
- New Iberia Research Center, University of Louisiana at Lafayette, New Iberia, LA, United States.,Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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13
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Regulation of Humoral Immune Responses and B Cell Tolerance by the IgM Fc Receptor (FcμR). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1254:75-86. [DOI: 10.1007/978-981-15-3532-1_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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14
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Nyamboya RA, Sutton BJ, Calvert RA. Mapping of the binding site for FcμR in human IgM-Fc. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1868:140266. [PMID: 31449905 PMCID: PMC6905151 DOI: 10.1016/j.bbapap.2019.140266] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/16/2019] [Accepted: 08/21/2019] [Indexed: 11/02/2022]
Abstract
FcμR is a high-affinity receptor for the Fc portion of human IgM. It participates in B cell activation, cell survival and proliferation, but the full range of its functions remains to be elucidated. The receptor has an extracellular immunoglobulin (Ig)-like domain homologous to those in Fcα/μR and pIgR, but unlike these two other IgM receptors which also bind IgA, FcμR exhibits a binding specificity for only IgM-Fc. Previous studies have suggested that the IgM/FcμR interaction mainly involves the Cμ4 domains with possible contributions from either Cμ3 or Cμ2. To define the binding site more precisely, we generated three recombinant IgM-Fc proteins with specific mutations in the Cμ3 and Cμ4 domains, as well as a construct lacking the Cμ2 domains, and analyzed their interaction with the extracellular Ig-like domain of FcμR using surface plasmon resonance analysis. There is a binding site for FcμR in each IgM heavy chain. Neither the absence of the Cμ2 domains nor the quadruple mutant D340S/Q341G/D342S/T343S (in Cμ3 adjacent to Cμ2) affected FcμR binding, whereas double mutant K361D/D416R (in Cμ3 at the Cμ4 interface) substantially decreased binding, and a single mutation Q510R (in Cμ4) completely abolished FcμR binding. We conclude that glutamine at position 510 in Cμ4 is critical for IgM binding to FcμR. This will facilitate discrimination between the distinct effects of FcμR interactions with soluble IgM and with the IgM BCR.
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Affiliation(s)
- Rosemary A Nyamboya
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom
| | - Brian J Sutton
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom
| | - Rosaleen A Calvert
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom.
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15
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Kubagawa H, Honjo K, Ohkura N, Sakaguchi S, Radbruch A, Melchers F, Jani PK. Functional Roles of the IgM Fc Receptor in the Immune System. Front Immunol 2019; 10:945. [PMID: 31130948 PMCID: PMC6509151 DOI: 10.3389/fimmu.2019.00945] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/12/2019] [Indexed: 12/14/2022] Open
Abstract
It is now evident from studies of mice unable to secrete IgM that both non-immune “natural” and antigen-induced “immune” IgM are important for protection against pathogens and for regulation of immune responses to self-antigens. Since identification of its Fc receptor (FcμR) by a functional cloning strategy in 2009, the roles of FcμR in these IgM effector functions have begun to be explored. Unlike Fc receptors for switched Ig isotypes (e.g., FcγRs, FcεRs, FcαR, Fcα/μR, pIgR, FcRn), FcμR is selectively expressed by lymphocytes: B, T, and NK cells in humans and only B cells in mice. FcμR may have dual signaling ability: one through a potential as yet unidentified adaptor protein non-covalently associating with the FcμR ligand-binding chain via a His in transmembrane segment and the other through its own Tyr and Ser residues in the cytoplasmic tail. FcμR binds pentameric and hexameric IgM with a high avidity of ~10 nM in solution, but more efficiently binds IgM when it is attached to a membrane component via its Fab region on the same cell surface (cis engagement). Four different laboratories have generated Fcmr-ablated mice and eight different groups of investigators have examined the resultant phenotypes. There have been some clear discrepancies reported that appear to be due to factors including differences in the exons of Fcmr that were targeted to generate the knockouts. One common feature among these different mutant mice, however, is their propensity to produce autoantibodies of both IgM and IgG isotypes. In this review, we briefly describe recent findings concerning the functions of FcμR in both mice and humans and propose a model for how FcμR plays a regulatory role in B cell tolerance.
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Affiliation(s)
| | - Kazuhito Honjo
- Department of Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Naganari Ohkura
- Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Shimon Sakaguchi
- Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | | | | | - Peter K Jani
- Deutsches Rheuma-Forschungszentrum, Berlin, Germany
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16
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Liu J, Wang Y, Xiong E, Hong R, Lu Q, Ohno H, Wang JY. Role of the IgM Fc Receptor in Immunity and Tolerance. Front Immunol 2019; 10:529. [PMID: 30967868 PMCID: PMC6438924 DOI: 10.3389/fimmu.2019.00529] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 02/27/2019] [Indexed: 11/13/2022] Open
Abstract
Immunoglobulin (Ig) M is the first antibody isotype to appear during evolution, ontogeny and immune responses. IgM not only serves as the first line of host defense against infections but also plays an important role in immune regulation and immunological tolerance. For many years, IgM is thought to function by binding to antigen and activating complement system. With the discovery of the IgM Fc receptor (FcμR), it is now clear that IgM can also elicit its function through FcμR. In this review, we will describe the molecular characteristics of FcμR, its role in B cell development, maturation and activation, humoral immune responses, host defense, and immunological tolerance. We will also discuss the functional relationship between IgM-complement and IgM-FcμR pathways in regulating immunity and tolerance. Finally, we will discuss the potential involvement of FcμR in human diseases.
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Affiliation(s)
- Jun Liu
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ying Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ermeng Xiong
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Rongjian Hong
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Qing Lu
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Hiroshi Ohno
- RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
| | - Ji-Yang Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
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17
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Glycan-independent binding and internalization of human IgM to FCMR, its cognate cellular receptor. Sci Rep 2017; 7:42989. [PMID: 28230186 PMCID: PMC5322398 DOI: 10.1038/srep42989] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 01/17/2017] [Indexed: 12/17/2022] Open
Abstract
IgM is the first antibody to be produced in immune responses and plays an important role in the neutralization of bacteria and viruses. Human IgM is heavily glycosylated, featuring five N-linked glycan sites on the μ chain and one on the J-chain. Glycosylation of IgG is known to modulate the effector functions of Fcγ receptors. In contrast, little is known about the effect of glycosylation on IgM binding to the human Fcμ receptor (hFCMR). In this study, we identify the Cμ4 domain of IgM as the target of hFCMR, and show that binding and internalization of IgM by hFCMR is glycan-independent. We generated a homology-based structure for hFCMR and used molecular dynamic simulations to show how this interaction with IgM may occur. Finally, we reveal an inhibitory function for IgM in the proliferation of T cells.
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18
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Akula S, Hellman L. The Appearance and Diversification of Receptors for IgM During Vertebrate Evolution. Curr Top Microbiol Immunol 2017; 408:1-23. [PMID: 28884191 DOI: 10.1007/82_2017_22] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Three different receptors that interact with the constant domains of IgM have been identified: the polymeric immunoglobulin (Ig) receptor (PIGR), the dual receptor for IgA/IgM (FcαµR) and the IgM receptor (FcµR). All of them are related in structure and located in the same chromosomal region in mammals. The functions of the PIGRs are to transport IgM and IgA into the intestinal lumen and to saliva and tears, whereas the FcαµRs enhance uptake of immune complexes and antibody coated bacteria and viruses by B220+ B cells and phagocytes, as well as dampening the Ig response to thymus-independent antigens. The FcµRs have broad-spectrum effects on B-cell development including effects on IgM homeostasis, B-cell survival, humoral immune responses and also in autoantibody formation. The PIGR is the first of these receptors to appear during vertebrate evolution and is found in bony fish and all tetrapods but not in cartilaginous fish. The FcµR is present in all extant mammalian lineages and also in the Chinese and American alligators, suggesting its appearance with early reptiles. Currently the FcαµR has only been found in mammals and is most likely the evolutionary youngest of the three receptors. In bony fish, the PIGR has either 2, 3, 4, 5 or 6 extracellular Ig-like domains, whereas in amphibians, reptiles and birds it has 4 domains, and 5 in all mammals. The increase in domain number from 4 to 5 in mammals has been proposed to enhance the interaction with IgA. Both the FcαµRs and the FcµRs contain only one Ig domain; the domain that confers Ig binding. In both of these receptors this domain shows the highest degree of sequence similarity to domain 1 of the PIGR. All Ig domains of these three receptors are V type domains, indicating they all have the same origin although they have diversified extensively in function during vertebrate evolution by changing expression patterns and cytoplasmic signaling motifs.
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Affiliation(s)
- Srinivas Akula
- Department of Cell and Molecular Biology, Uppsala University, The Biomedical Center, Box 596, 751 24, Uppsala, Sweden
| | - Lars Hellman
- Department of Cell and Molecular Biology, Uppsala University, The Biomedical Center, Box 596, 751 24, Uppsala, Sweden.
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19
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Kubagawa H, Skopnik CM, Zimmermann J, Durek P, Chang HD, Yoo E, Bertoli LF, Honjo K, Radbruch A. Authentic IgM Fc Receptor (FcμR). Curr Top Microbiol Immunol 2017; 408:25-45. [PMID: 28702710 DOI: 10.1007/82_2017_23] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Since the bona fide Fc receptor for IgM antibody (FcµR) was identified eight years ago, much progress has been made in defining its biochemical nature, cellular distribution, and effector function. However, there are clearly conflicting results, especially about the cellular distribution and function of murine FcµR. In this short article, we will discuss recent findings from us and other investigators along with our interpretations and comments that may help to resolve the existing puzzles and should open new avenues of investigation.
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Affiliation(s)
- Hiromi Kubagawa
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany.
| | | | - Jakob Zimmermann
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
| | - Pawel Durek
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
| | - Hyun-Dong Chang
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
| | - Esther Yoo
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
| | | | - Kazuhito Honjo
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35209, USA
| | - Andreas Radbruch
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
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20
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Malik M, Arora P, Sachdeva R, Sharma L, Ramachandran VG, Pal R. Elucidation of the potential disease-promoting influence of IgM apoptotic cell-reactive antibodies in lupus. Lupus 2016; 25:684-98. [DOI: 10.1177/0961203315624023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 12/01/2015] [Indexed: 12/11/2022]
Abstract
The undigested remnants of apoptosis are believed to stimulate the generation of autoantibodies in lupus. The biological properties of initiator, disease-specific IgM antibodies that specifically recognize apoptotic cells, readily detected in the sera of lupus patients, remain unclear. Apoptotic cell-reactive IgM monoclonal antibodies (generated from lupus-prone mice), as opposed to control IgM, preferentially stimulated maturation of bone marrow-derived dendritic cells (BMDCs) derived from such mice, relative to BMDCs derived from healthy mice. An influence of both antibody specificity and cell genotype was also apparent in the secretion of signature inflammatory cytokines. Immunization of such antibodies in lupus-prone animals induced increases in total serum IgG levels, with the elicited antibodies also preferentially recognizing moieties on dying cells. An expanded specificity was apparent both upon Western blot on cellular lysate and from the enhanced recognition of dsDNA, Ro60, RNP68 and Sm; the antibody most efficient in mediating autoreactive diversity, while being germline encoded, also induced the highest degree of phenotypic changes on BMDCs. Apoptotic cell-reactive IgM antibodies may therefore be potentially capable of influencing the course of systemic autoimmune disease by affecting both innate and adaptive immunity.
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Affiliation(s)
- M Malik
- Department of Microbiology, University College of Medical Sciences & Guru Teg Bahadur Hospital, Delhi, India
| | - P Arora
- National Institute of Immunology, New Delhi, India
| | - R Sachdeva
- National Institute of Immunology, New Delhi, India
| | - L Sharma
- National Institute of Immunology, New Delhi, India
| | - V G Ramachandran
- Department of Microbiology, University College of Medical Sciences & Guru Teg Bahadur Hospital, Delhi, India
| | - R Pal
- National Institute of Immunology, New Delhi, India
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21
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Kubagawa H, Carroll MC, Jacob CO, Lang KS, Lee KH, Mak T, McAndrews M, Morse HC, Nolan GP, Ohno H, Richter GH, Seal R, Wang JY, Wiestner A, Coligan JE. Nomenclature of Toso, Fas apoptosis inhibitory molecule 3, and IgM FcR. THE JOURNAL OF IMMUNOLOGY 2015; 194:4055-7. [PMID: 25888699 DOI: 10.4049/jimmunol.1500222] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hiromi Kubagawa and John E. Coligan coordinated an online meeting to define an appropriate nomenclature for the cell surface glycoprotein presently designated by different names: Toso, Fas apoptosis inhibitory molecule 3 (FAIM3), and IgM FcR (FcμR). FAIM3 and Faim3 are the currently approved symbols for the human and mouse genes, respectively, in the National Center for Biotechnology Information, Ensembl, and other databases. However, recent functional results reported by several groups of investigators strongly support a recommendation for renaming FAIM3/Faim3 as FCMR/Fcmr, a name better reflecting its physiological function as the FcR for IgM. Participants included 12 investigators involved in studying Toso/FAIM3(Faim3)/FμR, representatives from the Human Genome Nomenclature Committee (Ruth Seal) and the Mouse Genome Nomenclature Committee (Monica McAndrews), and an observer from the IgM research field (Michael Carroll). In this article, we provide a brief background of the key research on the Toso/FAIM3(Faim3)/FcμR proteins, focusing on the ligand specificity and functional activity, followed by a brief summary of discussion about adopting a single name for this molecule and its gene and a resulting recommendation for genome nomenclature committees.
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Affiliation(s)
- Hiromi Kubagawa
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294;
| | | | - Chaim O Jacob
- Department of Medicine, University of Southern California School of Medicine, Los Angeles, CA 90033
| | - Karl S Lang
- Institute for Immunology, University of Duisburg-Essen, Essen 45147, Germany
| | - Kyeong-Hee Lee
- Institute for Clinical Chemistry, Hannover Medical School, Hannover 30625, Germany
| | - Tak Mak
- Campbell Family Institute for Breast Cancer Research, Princess Margaret Cancer Centre/University Health Network, Toronto, Ontario M5T 2M9, Canada
| | - Monica McAndrews
- Mouse Genome Informatics, Jackson Laboratory, Bar Harbor, ME 04609
| | - Herbert C Morse
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852
| | - Garry P Nolan
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305
| | - Hiroshi Ohno
- Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa 230-0045, Japan
| | - Günther H Richter
- Kinderklinik, Klinikum Rechts der Isar, Technische Universität München, Munich 81664, Germany
| | - Ruth Seal
- Human Genome Organisation Gene Nomenclature Committee, European Bioinformatics Institute, Wellcome Trust Genome Campus Hinxton, Cambridgeshire CB10 1SD, United Kingdom
| | - Ji-Yang Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; and
| | - Adrian Wiestner
- Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - John E Coligan
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852;
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