1
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Marie AL, Gao Y, Ivanov AR. Native N-glycome profiling of single cells and ng-level blood isolates using label-free capillary electrophoresis-mass spectrometry. Nat Commun 2024; 15:3847. [PMID: 38719792 PMCID: PMC11079027 DOI: 10.1038/s41467-024-47772-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 04/12/2024] [Indexed: 05/12/2024] Open
Abstract
The development of reliable single-cell dispensers and substantial sensitivity improvement in mass spectrometry made proteomic profiling of individual cells achievable. Yet, there are no established methods for single-cell glycome analysis due to the inability to amplify glycans and sample losses associated with sample processing and glycan labeling. In this work, we present an integrated platform coupling online in-capillary sample processing with high-sensitivity label-free capillary electrophoresis-mass spectrometry for N-glycan profiling of single mammalian cells. Direct and unbiased quantitative characterization of single-cell surface N-glycomes are demonstrated for HeLa and U87 cells, with the detection of up to 100 N-glycans per single cell. Interestingly, N-glycome alterations are unequivocally detected at the single-cell level in HeLa and U87 cells stimulated with lipopolysaccharide. The developed workflow is also applied to the profiling of ng-level amounts (5-500 ng) of blood-derived protein, extracellular vesicle, and total plasma isolates, resulting in over 170, 220, and 370 quantitated N-glycans, respectively.
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Affiliation(s)
- Anne-Lise Marie
- Barnett Institute of Chemical and Biological Analysis, Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, MA, 02115, US
| | - Yunfan Gao
- Barnett Institute of Chemical and Biological Analysis, Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, MA, 02115, US
| | - Alexander R Ivanov
- Barnett Institute of Chemical and Biological Analysis, Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, MA, 02115, US.
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2
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Ivanov A, Marie AL, Gao Y. In-capillary sample processing coupled to label-free capillary electrophoresis-mass spectrometry to decipher the native N-glycome of single mammalian cells and ng-level blood isolates. RESEARCH SQUARE 2023:rs.3.rs-3500983. [PMID: 38014012 PMCID: PMC10680937 DOI: 10.21203/rs.3.rs-3500983/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The development of reliable single-cell dispensers and substantial sensitivity improvement in mass spectrometry made proteomic profiling of individual cells achievable. Yet, there are no established methods for single-cell glycome analysis due to the inability to amplify glycans and sample losses associated with sample processing and glycan labeling. In this work, we developed an integrated platform coupling online in-capillary sample processing with high-sensitivity label-free capillary electrophoresis-mass spectrometry for N-glycan profiling of single mammalian cells. Direct and unbiased characterization and quantification of single-cell surface N-glycomes were demonstrated for HeLa and U87 cells, with the detection of up to 100 N-glycans per single cell. Interestingly, N-glycome alterations were unequivocally detected at the single-cell level in HeLa and U87 cells stimulated with lipopolysaccharide. The developed workflow was also applied to the profiling of ng-level amounts of blood-derived protein, extracellular vesicle, and total plasma isolates, resulting in over 170, 220, and 370 quantitated N-glycans, respectively.
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3
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Haslund-Gourley B, Woloszcuk K, Hou J, Connors J, Cusimano G, Bell M, Taramangalam B, Fourati S, Mege N, Bernui M, Altman M, Krammer F, van Bakel H, Maecker H, Wigdahl B, Cairns C, Haddad E, Comunale M. IgM N-glycosylation correlates with COVID-19 severity and rate of complement deposition. RESEARCH SQUARE 2023:rs.3.rs-2939468. [PMID: 37398192 PMCID: PMC10312960 DOI: 10.21203/rs.3.rs-2939468/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The glycosylation of IgG plays a critical role during human SARS-CoV-2, activating immune cells and inducing cytokine production. However, the role of IgM N-glycosylation has not been studied during acute viral infection in humans. In vitro evidence suggests that the glycosylation of IgM inhibits T cell proliferation and alters complement activation rates. The analysis of IgM N-glycosylation from healthy controls and hospitalized COVID-19 patients reveals that mannosylation and sialyation levels associate with COVID-19 severity. Specifically, we find increased di- and tri-sialylated glycans and altered mannose glycans in total serum IgM in severe COVID-19 patients when compared to moderate COVID-19 patients. This is in direct contrast with the decrease of sialic acid found on the serum IgG from the same cohorts. Moreover, the degree of mannosylation and sialylation correlated significantly with markers of disease severity: D-dimer, BUN, creatinine, potassium, and early anti-COVID-19 amounts of IgG, IgA, and IgM. Further, IL-16 and IL-18 cytokines showed similar trends with the amount of mannose and sialic acid present on IgM, implicating these cytokines' potential to impact glycosyltransferase expression during IgM production. When examining PBMC mRNA transcripts, we observe a decrease in the expression of Golgi mannosidases that correlates with the overall reduction in mannose processing we detect in the IgM N-glycosylation profile. Importantly, we found that IgM contains alpha-2,3 linked sialic acids in addition to the previously reported alpha-2,6 linkage. We also report that antigen-specific IgM antibody-dependent complement deposition is elevated in severe COVID-19 patients. Taken together, this work links the immunoglobulin M N-glycosylation with COVID-19 severity and highlights the need to understand the connection between IgM glycosylation and downstream immune function during human disease.
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4
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Ji C, Shen H, Su C, Li Y, Chen S, Sharp TH, Xiao J. Plasmodium falciparum has evolved multiple mechanisms to hijack human immunoglobulin M. Nat Commun 2023; 14:2650. [PMID: 37156765 PMCID: PMC10167334 DOI: 10.1038/s41467-023-38320-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 04/25/2023] [Indexed: 05/10/2023] Open
Abstract
Plasmodium falciparum causes the most severe malaria in humans. Immunoglobulin M (IgM) serves as the first line of humoral defense against infection and potently activates the complement pathway to facilitate P. falciparum clearance. A number of P. falciparum proteins bind IgM, leading to immune evasion and severe disease. However, the underlying molecular mechanisms remain unknown. Here, using high-resolution cryo-electron microscopy, we delineate how P. falciparum proteins VAR2CSA, TM284VAR1, DBLMSP, and DBLMSP2 target IgM. Each protein binds IgM in a different manner, and together they present a variety of Duffy-binding-like domain-IgM interaction modes. We further show that these proteins interfere directly with IgM-mediated complement activation in vitro, with VAR2CSA exhibiting the most potent inhibitory effect. These results underscore the importance of IgM for human adaptation of P. falciparum and provide critical insights into its immune evasion mechanism.
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Affiliation(s)
- Chenggong Ji
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Changping Laboratory, Beijing, PR China
| | - Hao Shen
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Chen Su
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Yaxin Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Shihua Chen
- Joint Graduate Program of Peking-Tsinghua-NIBS, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Section Electron Microscopy, Leiden University Medical Center, 2300, RC, Leiden, The Netherlands
| | - Junyu Xiao
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China.
- Changping Laboratory, Beijing, PR China.
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
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5
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Chen Q, Menon RP, Masino L, Tolar P, Rosenthal PB. Structural basis for Fc receptor recognition of immunoglobulin M. Nat Struct Mol Biol 2023:10.1038/s41594-023-00985-x. [PMID: 37095205 DOI: 10.1038/s41594-023-00985-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/31/2023] [Indexed: 04/26/2023]
Abstract
Immunoglobulin Fc receptors are cell surface transmembrane proteins that bind to the Fc constant region of antibodies and play critical roles in regulating immune responses by activation of immune cells, clearance of immune complexes and regulation of antibody production. FcμR is the immunoglobulin M (IgM) antibody isotype-specific Fc receptor involved in the survival and activation of B cells. Here we reveal eight binding sites for the human FcμR immunoglobulin domain on the IgM pentamer by cryogenic electron microscopy. One of the sites overlaps with the binding site for the polymeric immunoglobulin receptor (pIgR), but a different mode of FcμR binding explains its antibody isotype specificity. Variation in FcμR binding sites and their occupancy reflects the asymmetry of the IgM pentameric core and the versatility of FcμR binding. The complex explains engagement with polymeric serum IgM and the monomeric IgM B-cell receptor (BCR).
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Affiliation(s)
- Qu Chen
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Rajesh P Menon
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK
| | - Laura Masino
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Pavel Tolar
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK.
- Institute of Immunity and Transplantation, University College London, London, UK.
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, UK.
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6
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Vattepu R, Sneed SL, Anthony RM. Sialylation as an Important Regulator of Antibody Function. Front Immunol 2022; 13:818736. [PMID: 35464485 PMCID: PMC9021442 DOI: 10.3389/fimmu.2022.818736] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 03/17/2022] [Indexed: 12/14/2022] Open
Abstract
Antibodies play a critical role in linking the adaptive immune response to the innate immune system. In humans, antibodies are categorized into five classes, IgG, IgM, IgA, IgE, and IgD, based on constant region sequence, structure, and tropism. In serum, IgG is the most abundant antibody, comprising 75% of antibodies in circulation, followed by IgA at 15%, IgM at 10%, and IgD and IgE are the least abundant. All human antibody classes are post-translationally modified by sugars. The resulting glycans take on many divergent structures and can be attached in an N-linked or O-linked manner, and are distinct by antibody class, and by position on each antibody. Many of these glycan structures on antibodies are capped by sialic acid. It is well established that the composition of the N-linked glycans on IgG exert a profound influence on its effector functions. However, recent studies have described the influence of glycans, particularly sialic acid for other antibody classes. Here, we discuss the role of glycosylation, with a focus on terminal sialylation, in the biology and function across all antibody classes. Sialylation has been shown to influence not only IgG, but IgE, IgM, and IgA biology, making it an important and unappreciated regulator of antibody function.
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Affiliation(s)
- Ravi Vattepu
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Sunny Lyn Sneed
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Robert M Anthony
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
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7
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Treger RS, Fink SL. Beyond Titer: Expanding the Scope of Clinical Autoantibody Testing. J Appl Lab Med 2022; 7:99-113. [DOI: 10.1093/jalm/jfab123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/17/2021] [Indexed: 11/14/2022]
Abstract
Abstract
Background
Autoantibodies that bind self-antigens are a hallmark of autoimmune diseases, but can also be present in healthy individuals. Clinical assays that detect and titer antigen-specific autoantibodies are an important component of the diagnosis and monitoring of autoimmune diseases. Autoantibodies may contribute to disease pathogenesis via effector functions that are dictated by both the antigen-binding site and constant domain.
Content
In this review, we discuss features of antibodies, in addition to antigen-binding specificity, which determine effector function. These features include class, subclass, allotype, and glycosylation. We discuss emerging data indicating that analysis of these antibody features may be informative for diagnosis and monitoring of autoimmune diseases. We also consider methodologies to interrogate these features and consider how they could be implemented in the clinical laboratory.
Summary
Future autoantibody assays may incorporate assessment of additional antibody features that contribute to autoimmune disease pathogenesis and provide added clinical value.
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Affiliation(s)
- Rebecca S Treger
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Susan L Fink
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
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8
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Kubagawa H, Skopnik CM, Al-Qaisi K, Calvert RA, Honjo K, Kubagawa Y, Teuber R, Aliabadi PM, Enghard P, Radbruch A, Sutton BJ. Differences between Human and Mouse IgM Fc Receptor (FcµR). Int J Mol Sci 2021; 22:ijms22137024. [PMID: 34209905 PMCID: PMC8267714 DOI: 10.3390/ijms22137024] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 01/02/2023] Open
Abstract
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 the bona fide IgM Fc receptor (FcµR) was identified in humans by a functional cloning strategy in 2009, the roles of FcµR in these IgM effector functions have begun to be explored. In this short essay, we describe the differences between human and mouse FcµRs in terms of their identification processes, cellular distributions and ligand binding activities with emphasis on our recent findings from the mutational analysis of human FcµR. We have identified at least three sites of human FcµR, i.e., Asn66 in the CDR2, Lys79 to Arg83 in the DE loop and Asn109 in the CDR3, responsible for its constitutive IgM-ligand binding. Results of computational structural modeling analysis are consistent with these mutational data and a model of the ligand binding, Ig-like domain of human FcµR is proposed. Serendipitously, substitution of Glu41 and Met42 in the CDR1 of human FcµR with mouse equivalents Gln and Leu, either single or more prominently in combination, enhances both the receptor expression and IgM binding. These findings would help in the future development of preventive and therapeutic interventions targeting FcµR.
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Affiliation(s)
- Hiromi Kubagawa
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany; (C.M.S.); (K.A.-Q.); (R.T.); (P.M.A.); (A.R.)
- Correspondence: ; Tel.: +49-030-2846-0782
| | - Christopher M. Skopnik
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany; (C.M.S.); (K.A.-Q.); (R.T.); (P.M.A.); (A.R.)
| | - Khlowd Al-Qaisi
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany; (C.M.S.); (K.A.-Q.); (R.T.); (P.M.A.); (A.R.)
| | - Rosaleen A. Calvert
- Randall Centre for Cell and Molecular Biophysics, King’s College, London SE1 1UL, UK; (R.A.C.); (B.J.S.)
| | - Kazuhito Honjo
- Department of Pathology of University of Alabama at Birmingham, Birmingham, AL 35294, USA.; (K.H.); (Y.K.)
| | - Yoshiki Kubagawa
- Department of Pathology of University of Alabama at Birmingham, Birmingham, AL 35294, USA.; (K.H.); (Y.K.)
| | - Ruth Teuber
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany; (C.M.S.); (K.A.-Q.); (R.T.); (P.M.A.); (A.R.)
| | - Pedram Mahmoudi Aliabadi
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany; (C.M.S.); (K.A.-Q.); (R.T.); (P.M.A.); (A.R.)
| | - Philipp Enghard
- Department of Nephrology and Medical Intensive Care, Charité-Universitätmedizin, 10117 Berlin, Germany;
| | - Andreas Radbruch
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany; (C.M.S.); (K.A.-Q.); (R.T.); (P.M.A.); (A.R.)
| | - Brian J. Sutton
- Randall Centre for Cell and Molecular Biophysics, King’s College, London SE1 1UL, UK; (R.A.C.); (B.J.S.)
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9
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Ivashenka A, Wunder C, Chambon V, Sandhoff R, Jennemann R, Dransart E, Podsypanina K, Lombard B, Loew D, Lamaze C, Poirier F, Gröne HJ, Johannes L, Shafaq-Zadah M. Glycolipid-dependent and lectin-driven transcytosis in mouse enterocytes. Commun Biol 2021; 4:173. [PMID: 33564097 PMCID: PMC7873212 DOI: 10.1038/s42003-021-01693-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 01/13/2021] [Indexed: 01/05/2023] Open
Abstract
Glycoproteins and glycolipids at the plasma membrane contribute to a range of functions from growth factor signaling to cell adhesion and migration. Glycoconjugates undergo endocytic trafficking. According to the glycolipid-lectin (GL-Lect) hypothesis, the construction of tubular endocytic pits is driven in a glycosphingolipid-dependent manner by sugar-binding proteins of the galectin family. Here, we provide evidence for a function of the GL-Lect mechanism in transcytosis across enterocytes in the mouse intestine. We show that galectin-3 (Gal3) and its newly identified binding partner lactotransferrin are transported in a glycosphingolipid-dependent manner from the apical to the basolateral membrane. Transcytosis of lactotransferrin is perturbed in Gal3 knockout mice and can be rescued by exogenous Gal3. Inside enterocytes, Gal3 is localized to hallmark structures of the GL-Lect mechanism, termed clathrin-independent carriers. These data pioneer the existence of GL-Lect endocytosis in vivo and strongly suggest that polarized trafficking across the intestinal barrier relies on this mechanism.
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Affiliation(s)
- Alena Ivashenka
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Endocytic Trafficking and Intracellular Delivery Team, Paris, France
| | - Christian Wunder
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Endocytic Trafficking and Intracellular Delivery Team, Paris, France
| | - Valerie Chambon
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Endocytic Trafficking and Intracellular Delivery Team, Paris, France
| | - Roger Sandhoff
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany
| | - Richard Jennemann
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany
| | - Estelle Dransart
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Endocytic Trafficking and Intracellular Delivery Team, Paris, France
| | - Katrina Podsypanina
- Institut Curie, Université PSL, UMR144 CNRS, Cell Biology and Cancer, Paris, France
| | - Bérangère Lombard
- Institut Curie, Université PSL, Mass Spectrometry and Proteomics Facility, Paris, France
| | - Damarys Loew
- Institut Curie, Université PSL, Mass Spectrometry and Proteomics Facility, Paris, France
| | - Christophe Lamaze
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Membrane Dynamics and Mechanics of Intracellular Signaling Team, Paris, France
| | - Francoise Poirier
- Institut Jacques Monod, UMR 7592 CNRS - Université Paris Diderot, 15 rue Hélène Brion, Paris, France
| | | | - Ludger Johannes
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Endocytic Trafficking and Intracellular Delivery Team, Paris, France.
| | - Massiullah Shafaq-Zadah
- Institut Curie, Université PSL, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology Unit, Endocytic Trafficking and Intracellular Delivery Team, Paris, France.
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10
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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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11
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Göritzer K, Strasser R. Glycosylation of Plant-Produced Immunoglobulins. EXPERIENTIA SUPPLEMENTUM (2012) 2021; 112:519-543. [PMID: 34687021 DOI: 10.1007/978-3-030-76912-3_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Many economically important protein-based therapeutics like monoclonal antibodies are glycosylated. Due to the recognized importance of this type of posttranslational modification, glycoengineering of expression systems to obtain highly active and homogenous therapeutics is an emerging field. Although most of the monoclonal antibodies on the market are still produced in mammalian expression platforms, plants are emerging as an alternative cost-effective and scalable production platform that allows precise engineering of glycosylation to produce targeted human glycoforms at large homogeneity. Apart from producing more effective antibodies, pure glycoforms are required in efforts to link biological functions to specific glycan structures. Much is already known about the role of IgG1 glycosylation and this antibody class is the dominant recombinant format that has been expressed in plants. By contrast, little attention has been paid to the glycoengineering of recombinant IgG subtypes and the other four classes of human immunoglobulins (IgA, IgD, IgE, and IgM). Except for IgD, all these antibody classes have been expressed in plants and the glycosylation has been analyzed in a site-specific manner. Here, we summarize the current data on glycosylation of plant-produced monoclonal antibodies and discuss the findings in the light of known functions for these glycans.
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Affiliation(s)
| | - Richard Strasser
- University of Natural Resources and Life Sciences Vienna, Vienna, Austria.
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12
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Meryk A, Pangrazzi L, Hagen M, Hatzmann F, Jenewein B, Jakic B, Hermann-Kleiter N, Baier G, Jylhävä J, Hurme M, Trieb K, Grubeck-Loebenstein B. Fcμ receptor as a Costimulatory Molecule for T Cells. Cell Rep 2020; 26:2681-2691.e5. [PMID: 30840890 DOI: 10.1016/j.celrep.2019.02.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/28/2019] [Accepted: 02/07/2019] [Indexed: 11/17/2022] Open
Abstract
Fc receptor for IgM (FcμR)-deficient mice display dysregulated function of neutrophils, dendritic cells, and B cells. The relevance of FcμR to human T cells is still unknown. We show that FcμR is mostly stored inside the cell and that surface expression is tightly regulated. Decreased surface expression on T cells from elderly individuals is associated with alterations in the methylation pattern of the FCMR gene. Binding and internalization of IgM stimulate transport of FcμR to the cell surface to ensure sustained IgM uptake. Concurrently, IgM accumulates within the cell, and the surface expression of other receptors increases, among them the T cell receptor (TCR) and costimulatory molecules. This leads to enhanced TCR signaling, proliferation, and cytokine release, in response to low, but not high, doses of antigen. Our findings indicate that FcμR is an important regulator of T cell function and reveal an additional mode of interaction between B and T cells.
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Affiliation(s)
- Andreas Meryk
- Department of Immunology, Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria.
| | - Luca Pangrazzi
- Department of Immunology, Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
| | - Magdalena Hagen
- Department of Immunology, Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
| | - Florian Hatzmann
- Department of Immunology, Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
| | - Brigitte Jenewein
- Department of Immunology, Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
| | - Bojana Jakic
- Division of Translational Cell Genetics, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Natascha Hermann-Kleiter
- Division of Translational Cell Genetics, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Gottfried Baier
- Division of Translational Cell Genetics, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Juulia Jylhävä
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, 17177 Stockholm, Sweden
| | - Mikko Hurme
- Faculty of Medicine and Life Sciences, University of Tampere, Tampere 33014, Finland
| | - Klemens Trieb
- Department of Orthopedic Surgery, Hospital Wels-Grieskirchen, 4600 Wels, Austria
| | - Beatrix Grubeck-Loebenstein
- Department of Immunology, Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
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Genetic Diversity of IGHM and IGHE in the Leporids Revealed Different Patterns of Diversity in the Two European Rabbit Subspecies ( O. cuniculus algirus and O. c. cuniculus). Animals (Basel) 2019; 9:ani9110955. [PMID: 31718112 PMCID: PMC6912466 DOI: 10.3390/ani9110955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 11/19/2022] Open
Abstract
Simple Summary The study of European rabbit immunoglobulin genes has contributed decisively to the current knowledge on antibody structure and diversification. The European rabbit has also been increasingly used as an animal model for the study of many human diseases, such as syphilis, tuberculosis, and AIDS. As such, the study of its immune system genes is of crucial relevance, but the study of rabbit immunoglobulins has focused only on the IgG and IgA antibodies. In this study, we added to the knowledge of the rabbit immune system by investigating the genetic diversity of two antibodies, IgM and IgE, in wild and domestic rabbits as well as other rabbit close species. With the data obtained in this study, we showed a high similarity between the different rabbit close species studied and we pointed out important genetic differences in the wild and domestic rabbits. Our findings are a valuable tool for the management of rabbit wild populations and domestic breeds and may contribute to the identification of immunoglobulins genetic variants with greater efficiency against pathogens. Abstract The European rabbit (Oryctolagus cuniculus) has been an important model for immunological studies but the study of its immunoglobulins (Ig) has been restricted to its unique IgA and IgG. Here, we studied the genetic diversity of IgM and IgE in several species of leporids and performed population genetics studies on European rabbit wild populations and domestic breeds. The leporids sequencing showed that these Ig are well conserved (98% sequence similarity among leporids), For IgM the Cµ1 and Cµ4 were the most diverse and most conserved domains, respectively, while for IgE the Cε1 was the most diverse domain and Cε2 and Cε3 the most conserved domains. The differences in the pattern of most conserved and most diverse domain between the Ig isotypes are most likely related to each isotype function. The genetic population data showed contrasting results for IgM and IgE. For both Ig, as expected, a greater diversity was observed in the original species range, the Iberian Peninsula. However, unexpectedly the genetic diversity found for IgE in the domestic animals is higher than that for the French wild populations. These results will increase knowledge of the genetic diversity of leporids and wild and domestic rabbit populations and are important tools for the management of wild populations and rabbitries.
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Blandino R, Baumgarth N. Secreted IgM: New tricks for an old molecule. J Leukoc Biol 2019; 106:1021-1034. [PMID: 31302940 PMCID: PMC6803036 DOI: 10.1002/jlb.3ri0519-161r] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/25/2019] [Accepted: 06/26/2019] [Indexed: 12/27/2022] Open
Abstract
Secreted IgM (sIgM) is a multifunctional evolutionary conserved antibody that is critical for the maintenance of tissue homeostasis as well as the development of fully protective humoral responses to pathogens. Constitutive secretion of self- and polyreactive natural IgM, produced mainly by B-1 cells, provides a circulating antibody that engages with autoantigens as well as invading pathogens, removing apoptotic and other cell debris and initiating strong immune responses. Pathogen-induced IgM production by B-1 and conventional B-2 cells strengthens this early, passive layer of IgM-mediated immune defense and regulates subsequent IgG production. The varied effects of secreted IgM on immune homeostasis and immune defense are facilitated through its binding to numerous different cell types via different receptors. Recent studies identified a novel function for pentameric IgM, namely as a transporter for the effector protein ″apoptosis-inhibitor of macrophages″ (AIM/CD5L). This review aims to provide a summary of the known functions and effects of sIgM on immune homeostasis and immune defense, and its interaction with its various receptors, and to highlight the many critical immune regulatory functions of this ancient and fascinating immunoglobulin.
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Affiliation(s)
- Rebecca Blandino
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis
- Center for Comparative Medicine and University of California, Davis
| | - Nicole Baumgarth
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis
- Center for Comparative Medicine and University of California, Davis
- Dept. Pathology, Microbiology & Immunology, University of California, Davis
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15
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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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16
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A generalized quantitative antibody homeostasis model: maintenance of global antibody equilibrium by effector functions. Clin Transl Immunology 2017; 6:e161. [PMID: 29201362 PMCID: PMC5704100 DOI: 10.1038/cti.2017.50] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/06/2017] [Accepted: 10/06/2017] [Indexed: 12/25/2022] Open
Abstract
The homeostasis of antibodies can be characterized as a balanced production, target-binding and receptor-mediated elimination regulated by an interaction network, which controls B-cell development and selection. Recently, we proposed a quantitative model to describe how the concentration and affinity of interacting partners generates a network. Here we argue that this physical, quantitative approach can be extended for the interpretation of effector functions of antibodies. We define global antibody equilibrium as the zone of molar equivalence of free antibody, free antigen and immune complex concentrations and of dissociation constant of apparent affinity: [Ab]=[Ag]=[AbAg]=KD. This zone corresponds to the biologically relevant KD range of reversible interactions. We show that thermodynamic and kinetic properties of antibody–antigen interactions correlate with immunological functions. The formation of stable, long-lived immune complexes correspond to a decrease of entropy and is a prerequisite for the generation of higher-order complexes. As the energy of formation of complexes increases, we observe a gradual shift from silent clearance to inflammatory reactions. These rules can also be applied to complement activation-related immune effector processes, linking the physicochemical principles of innate and adaptive humoral responses. Affinity of the receptors mediating effector functions shows a wide range of affinities, allowing the continuous sampling of antibody-bound antigen over the complete range of concentrations. The generation of multivalent, multicomponent complexes triggers effector functions by crosslinking these receptors on effector cells with increasing enzymatic degradation potential. Thus, antibody homeostasis is a thermodynamic system with complex network properties, nested into the host organism by proper immunoregulatory and effector pathways. Maintenance of global antibody equilibrium is achieved by innate qualitative signals modulating a quantitative adaptive immune system, which regulates molecular integrity of the host by tuning the degradation and recycling of molecules from silent removal to inflammatory elimination.
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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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