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Etayo A, Bjørgen H, Hordvik I, Øvergård AC. Possible transport routes of IgM to the gut of teleost fish. FISH & SHELLFISH IMMUNOLOGY 2024; 149:109583. [PMID: 38657879 DOI: 10.1016/j.fsi.2024.109583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/12/2024] [Accepted: 04/22/2024] [Indexed: 04/26/2024]
Abstract
Fish rely on mucosal surfaces as their first defence barrier against pathogens. Maintaining mucosal homeostasis is therefore crucial for their overall well-being, and it is likely that secreted immunoglobulins (sIg) play a pivotal role in sustaining this balance. In mammals, the poly-Ig receptor (pIgR) is an essential component responsible for transporting polymeric Igs across mucosal epithelia. In teleost fish, a counterpart of pIgR has been identified and characterized, exhibiting structural differences and broader mRNA expression patterns compared to mammals. Despite supporting evidence for the binding of Igs to recombinant pIgR proteins, the absence of a joining chain (J-chain) in teleosts challenges the conventional understanding of Ig transport mechanisms. The transport of IgM to the intestine via the hepatobiliary route is observed in vertebrates and has been proposed in a few teleosts. Investigations on the stomachless fish, ballan wrasse, revealed a significant role of the hepatobiliary route and interesting possibilities for alternative IgM transport routes that might include pancreatic tissue. These findings highlight the importance of gaining a thorough understanding of the mechanisms behind Ig transport to the gut in various teleosts. This review aims to gather existing information on pIgR-mediated transport across epithelial cells and immunoglobulin transport pathways to the gut lumen in teleost fish. It provides comparative insights into the hepatobiliary transport of Igs to the gut, emphasizing the current understanding in teleost fish while exploring potential alternative pathways for Ig transport to the gut lumen. Despite significant progress in understanding various aspects, there is still much to uncover, especially concerning the diversity of mechanisms across different teleost species.
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Affiliation(s)
- Angela Etayo
- Institute of Marine Research, Bergen, Norway; Fish Health group, Department of Biological sciences, University of Bergen, Norway.
| | - Håvard Bjørgen
- Anatomy Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Ivar Hordvik
- Fish Health group, Department of Biological sciences, University of Bergen, Norway
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2
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Pinheiro A, de Sousa-Pereira P, Esteves PJ. The IgA of hares ( Lepus sp.) and rabbit confirms that the leporids IgA explosion is old and reveals a new case of trans-species polymorphism. Front Immunol 2023; 14:1192460. [PMID: 37600766 PMCID: PMC10435986 DOI: 10.3389/fimmu.2023.1192460] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 07/10/2023] [Indexed: 08/22/2023] Open
Abstract
Background Immunoglobulin A (IgA) is the mammalian mucosal antibody, providing an important line of defense against pathogens. With 15 IgA subclasses, the European rabbit has an extremely complex IgA system, strikingly more complex than most other mammals, which have only one IgA or, in the case of hominoids, two IgA subclasses. Similar to the two hominoid primate IGHA genes, the expansion of the rabbit IGHA genes appears to have begun in an ancestral lagomorph since multiple IgA copies were found by Southern blot analysis for the genera Sylvilagus, Lepus, and Ochotona. Results To gain a better insight into the extraordinary lagomorph IgA evolution, we sequenced, for the first time, expressed IgA genes for two Lepus species, L. europaeus and L. granatensis. These were aligned with the 15 rabbit IgA isotypes, and evolutionary analyses were conducted. The obtained phylogenetic tree shows that the Lepus IgA sequences cluster with and among the rabbit IgA isotypes, and the interspecies and intraspecies nucleotide genetic distances are similar. A comparison of the amino acid sequences of the Lepus and rabbit IgA confirms that there are two trans-species polymorphisms and that the rabbit and Lepus sequences share a common genetic pool. In fact, the main differences between the studied leporids IgAs reside in the characteristics of the hinge region. Conclusion The Lepus IgA sequences we have obtained strongly suggest that the great expansion of the leporid IGHA genes occurred in a common ancestral species and was then maintained in the descendants. A strong selective pressure caused the extraordinary expansion of the IGHA genes but then subsided, leading to the maintenance of the acquired polymorphisms in the descendants, with little subsequent divergence. This is a unique evolutionary pattern in which an ancient gene expansion has been maintained for approximately 18 million years.
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Affiliation(s)
- Ana Pinheiro
- Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto (CIBIO-UP), InBIO, Laboratório Associado, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
| | - Patrícia de Sousa-Pereira
- Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto (CIBIO-UP), InBIO, Laboratório Associado, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
| | - Pedro J. Esteves
- Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto (CIBIO-UP), InBIO, Laboratório Associado, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- Centro de Investigação em Tecnologias de Saúde (CITS), CESPU, Gandra, Portugal
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3
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Stosik M, Tokarz-Deptuła B, Deptuła W. Polymeric immunoglobulin receptor (pIgR) in ray-finned fish (Actinopterygii). FISH & SHELLFISH IMMUNOLOGY 2023; 138:108814. [PMID: 37211331 DOI: 10.1016/j.fsi.2023.108814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/11/2023] [Accepted: 05/11/2023] [Indexed: 05/23/2023]
Affiliation(s)
- Michał Stosik
- Institute of Biological Sciences, Faculty of Biological Sciences University of Zielona Góra, Poland
| | | | - Wiesław Deptuła
- Institute of Veterinary Medicine, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Poland
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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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Kim J, Lee JY, Kim HG, Kwak MW, Kang TH. Fc Receptor Variants and Disease: A Crucial Factor to Consider in the Antibody Therapeutics in Clinic. Int J Mol Sci 2021; 22:9489. [PMID: 34502398 PMCID: PMC8431278 DOI: 10.3390/ijms22179489] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/27/2021] [Accepted: 08/28/2021] [Indexed: 12/19/2022] Open
Abstract
The fragment crystallizable (Fc) domain of antibodies is responsible for their protective function and long-lasting serum half-life via Fc-mediated effector function, transcytosis, and recycling through its interaction with Fc receptors (FcRs) expressed on various immune leukocytes, epithelial, and endothelial cells. Therefore, the Fc-FcRs interaction is a control point of both endogenous and therapeutic antibody function. There are a number of reported genetic variants of FcRs, which include polymorphisms in (i) extracellular domain of FcRs, which change their affinities to Fc domain of antibodies; (ii) both cytoplasmic and intracellular domain, which alters the extent of signal transduction; and (iii) the promoter region of the FcRs gene, which affects the expression level of FcRs, thus being associated with the pathogenesis of disease indications. In this review, we firstly describe the correlation between the genetic variants of FcRs and immunological disorders by individual differences in the extent of FcRs-mediated regulations. Secondly, we discuss the influence of the genetic variants of FcRs on the susceptibility to infectious diseases or cancer in the perspective of FcRs-induced effector functions. Overall, we concluded that the genetic variants of FcRs are one of the key elements in the design of antibody therapeutics due to their variety of clinical outcomes among individuals.
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Affiliation(s)
- Jin Kim
- Department of Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Korea;
| | - Ji Young Lee
- Department of Chemistry, Kookmin University, Seoul 02707, Korea;
| | - Han Gil Kim
- Department of Biopharmaceutical Chemistry, Kookmin University, Seoul 02707, Korea; (H.G.K.); (M.W.K.)
| | - Min Woo Kwak
- Department of Biopharmaceutical Chemistry, Kookmin University, Seoul 02707, Korea; (H.G.K.); (M.W.K.)
| | - Tae Hyun Kang
- Department of Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Korea;
- Department of Chemistry, Kookmin University, Seoul 02707, Korea;
- Department of Biopharmaceutical Chemistry, Kookmin University, Seoul 02707, Korea; (H.G.K.); (M.W.K.)
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6
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Flowers EM, Neely HR, Guo J, Almeida T, Ohta Y, Castro CD, Flajnik MF. Identification of the Fc-alpha/mu receptor in Xenopus provides insight into the emergence of the poly-Ig receptor (pIgR) and mucosal Ig transport. Eur J Immunol 2021; 51:2590-2606. [PMID: 34411303 DOI: 10.1002/eji.202149383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/05/2021] [Indexed: 01/17/2023]
Abstract
The polyimmunoglobulin receptor (pIgR) transcytoses J chain-containing antibodies through mucosal epithelia. In mammals, two cis-duplicates of PIGR, FCMR, and FCAMR, flank the PIGR gene. A PIGR duplication is first found in amphibians, previously annotated as PIGR2 (herein xlFCAMR), and is expressed by APCs. We demonstrate that xlFcamR is the equivalent of mammalian FcamR. It has been assumed that pIgR is the oldest member of this family, yet our data could not distinguish whether PIGR or FCAMR emerged first; however, FCMR was the last family member to emerge. Interestingly, bony fish "pIgR" is not an orthologue of tetrapod pIgR, and possibly acquired its function via convergent evolution. PIGR/FCAMR/FCMR are members of a larger superfamily, including TREM, CD300, and NKp44, which we name the "double-disulfide Ig superfamily" (ddIgSF). Domains related to each ddIgSF family were identified in cartilaginous fish (sharks, chimeras) and encoded in a single gene cluster syntenic to the human pIgR locus. Thus, the ddIgSF families date back to the earliest antibody-based adaptive immunity, but apparently not before. Finally, our data strongly suggest that the J chain arose in evolution only for Ig multimerization. This study provides a framework for further studies of pIgR and the ddIgSF in vertebrates.
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Affiliation(s)
- Emily M Flowers
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Harold R Neely
- Department of Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Jacqueline Guo
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Tereza Almeida
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Yuko Ohta
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Caitlin D Castro
- Committee on Immunology and Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Martin F Flajnik
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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7
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Abstract
Among antibodies, IgA is unique because it has evolved to be secreted onto mucosal surfaces. The structure of IgA and the associated secretory component allow IgA to survive the highly proteolytic environment of mucosal surfaces but also substantially limit IgA's ability to activate effector functions on immune cells. Despite these characteristics, IgA is critical for both preventing enteric infections and shaping the local microbiome. IgA's function is determined by a distinct antigen-binding repertoire, composed of antibodies with a variety of specificities, from permissive polyspecificity to cross-reactivity to exquisite specificity to a single epitope, which act together to regulate intestinal bacteria. Development of the unique function and specificities of IgA is shaped by local cues provided by the gut-associated lymphoid tissue, driven by the constantly changing environment of the intestine and microbiota.
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Affiliation(s)
- Timothy W Hand
- R.K. Mellon Institute for Pediatric Research, Department of Pediatrics, Division of Infectious Diseases, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pennsylvania 15224, USA;
| | - Andrea Reboldi
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA;
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8
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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: 88] [Impact Index Per Article: 22.0] [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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9
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de Sousa-Pereira P, Woof JM. IgA: Structure, Function, and Developability. Antibodies (Basel) 2019; 8:antib8040057. [PMID: 31817406 PMCID: PMC6963396 DOI: 10.3390/antib8040057] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 11/24/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023] Open
Abstract
Immunoglobulin A (IgA) plays a key role in defending mucosal surfaces against attack by infectious microorganisms. Such sites present a major site of susceptibility due to their vast surface area and their constant exposure to ingested and inhaled material. The importance of IgA to effective immune defence is signalled by the fact that more IgA is produced than all the other immunoglobulin classes combined. Indeed, IgA is not just the most prevalent antibody class at mucosal sites, but is also present at significant concentrations in serum. The unique structural features of the IgA heavy chain allow IgA to polymerise, resulting in mainly dimeric forms, along with some higher polymers, in secretions. Both serum IgA, which is principally monomeric, and secretory forms of IgA are capable of neutralising and removing pathogens through a range of mechanisms, including triggering the IgA Fc receptor known as FcαRI or CD89 on phagocytes. The effectiveness of these elimination processes is highlighted by the fact that various pathogens have evolved mechanisms to thwart such IgA-mediated clearance. As the structure–function relationships governing the varied capabilities of this immunoglobulin class come into increasingly clear focus, and means to circumvent any inherent limitations are developed, IgA-based monoclonal antibodies are set to emerge as new and potent options in the therapeutic arena.
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Affiliation(s)
- Patrícia de Sousa-Pereira
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- CIBIO-InBIO, Campus Agrário de Vairão, University of Porto, 4485-661 Vairão, Portugal
| | - Jenny M. Woof
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Correspondence: ; Tel.: +44-1382-383389
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10
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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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11
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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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12
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Immunoglobulins and their receptors, and subversion of their protective roles by bacterial pathogens. Biochem Soc Trans 2017; 44:1651-1658. [PMID: 27913674 DOI: 10.1042/bst20160246] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/07/2016] [Accepted: 09/12/2016] [Indexed: 12/16/2022]
Abstract
Immunoglobulins (Igs) play critical roles in immune defence against infectious disease. They elicit potent elimination processes such as triggering complement activation and engaging specific Fc receptors present on immune cells, resulting in phagocytosis and other killing mechanisms. Many important pathogens have evolved mechanisms to subvert or evade Ig-mediated defence. One such mechanism used by several pathogenic bacteria features proteins that bind the Ig Fc region and compromise engagement of host effector molecules. Examples include different IgA-binding proteins produced by Staphylococcus aureus, Streptococcus pyogenes, and group B streptococci, all of which interact with the same interdomain region on IgA Fc. Since this region also forms the interaction site for the major human IgA-specific Fc receptor CD89, the bacteria are able to evade CD89-mediated clearance mechanisms. Similar disruption of Ig effector function by pathogen Ig-binding proteins is evident in other species. Remarkably, all the Ig-binding proteins studied in detail to date are seen to target the CH2-CH3 domain interface in the Ig Fc region, suggesting a common mode of immune evasion. A second Ig subversion mechanism that has evolved independently in numerous pathogens involves proteases that cleave Ig molecules within their hinge regions, uncoupling the antigen recognition capability of the Fab region from clearance mechanisms elicited by the Fc region. The emerging understanding of the structural basis for the recognition of Igs as substrates for these proteases and as interaction partners for Ig-binding proteins may open up new avenues for treatment or vaccination.
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13
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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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14
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Blackburn TE, Santiago T, Burrows PD. FCRLA-A Resident Endoplasmic Reticulum Protein that Associates with Multiple Immunoglobulin Isotypes in B Lineage Cells. Curr Top Microbiol Immunol 2017; 408:47-65. [PMID: 28879521 DOI: 10.1007/82_2017_40] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
FCRLA is homologous to receptors for the Fc portion of IgG (FcγR) and is located in the same region of human chromosome one, but has several unusual and unique features. It is a soluble resident ER protein retained in this organelle by unknown mechanisms involving the N-terminal domain, a disordered domain with three Cys residues in close proximity in the human protein. Unlike the FcγRs, FCRLA is not glycosylated and has no transmembrane region. FCRLA is included in this CTMI volume on IgM-binding proteins because it binds IgM in the ER, but quite surprisingly, given the isotype-restricted ligand specificity of the other FcRs, it also binds all other Ig isotypes so far tested, IgG and IgA. In the case of IgM, there is even preferential binding of the secretory and not the transmembrane form. Among B cells, FCRLA is most highly expressed in the germinal center and shows little expression in plasma cells. Based on these observations, we propose that one human FCRLA function is to stop GC B cells from secreting IgM, which would act as a decoy receptor, thus preventing the B cells from capturing antigen, processing it, and presenting the antigen-derived peptides to T follicular helper cells. Without help from these T cells, there would be limited B cell isotype switching, proliferation, and differentiation. On the other hand, FCRLA is downregulated in plasma cells, where IgM secretion is an essential function. FCRLA may also act as a chaperone involved by unknown mechanisms in the proper assembly of Ig molecules of all isotypes.
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Affiliation(s)
- Tessa E Blackburn
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Teresa Santiago
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Peter D Burrows
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
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15
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Shibuya A, Honda SI. Immune regulation by Fcα/μ receptor (CD351) on marginal zone B cells and follicular dendritic cells. Immunol Rev 2016; 268:288-95. [PMID: 26497528 DOI: 10.1111/imr.12345] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Although both Fcα/μ receptor (Fcα/μR) and polymeric Ig receptor (poly-IgR) are Fc receptors for IgA and IgM and are functionally and genetically related, the expression profile of Fcα/μR is unique. Unlike poly-IgR, Fcα/μR is expressed on marginal zone (MZ) B cells and follicular dendritic cells, suggesting that Fcα/μR plays an important role in humoral immune responses. Fcα/μR mediates endocytosis of the IgM immune complex (IC). Recent research demonstrated that Fcα/μR downregulated retention of the IgM IC with a T-independent (TI) antigen on MZ B cells and follicular dendritic cells due to endocytosis of the IgM IC, suppressing germinal center formation, affinity maturation, and memory B-cell generation in response to TI antigen challenge. In addition, Fcα/μR physically associates with Toll-like receptor 4 (TLR4) and augments TLR4 oligomerization and signaling in MZ B cells upon lipopolysaccharide (LPS) challenge, leading to increased proinflammatory cytokine production by MZ B cells. Thus, Fcα/μR is a unique Fc receptor that is involved in humoral immune responses and inflammation.
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Affiliation(s)
- Akira Shibuya
- Department of Immunology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.,Department of Immunology, Life Science Center of Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Ibaraki, Japan.,Department of Immunology, Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (CREST), University of Tsukuba, Ibaraki, Japan
| | - Shin-ichiro Honda
- Department of Immunology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
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16
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Abstract
IgG4, the least represented human IgG subclass in serum, is an intriguing antibody with unique biological properties, such as the ability to undergo Fab-arm exchange and limit immune complex formation. The lack of effector functions, such as antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity, is desirable for therapeutic purposes. IgG4 plays a protective role in allergy by acting as a blocking antibody, and inhibiting mast cell degranulation, but a deleterious role in malignant melanoma, by impeding IgG1-mediated anti-tumor immunity. These findings highlight the importance of understanding the interaction between IgG4 and Fcγ receptors. Despite a wealth of structural information for the IgG1 subclass, including complexes with Fcγ receptors, and structures for intact antibodies, high-resolution crystal structures were not reported for IgG4-Fc until recently. Here, we highlight some of the biological properties of human IgG4, and review the recent crystal structures of IgG4-Fc. We discuss the unexpected conformations adopted by functionally important Cγ2 domain loops, and speculate about potential implications for the interaction between IgG4 and FcγRs.
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Affiliation(s)
- Anna M Davies
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.,Medical Research Council & Asthma UK Centre in Allergic Mechanisms of Asthma, London, UK
| | - Brian J Sutton
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.,Medical Research Council & Asthma UK Centre in Allergic Mechanisms of Asthma, London, UK
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17
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Foss S, Watkinson R, Sandlie I, James LC, Andersen JT. TRIM21: a cytosolic Fc receptor with broad antibody isotype specificity. Immunol Rev 2016; 268:328-39. [PMID: 26497531 PMCID: PMC4670481 DOI: 10.1111/imr.12363] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Antibodies are key molecules in the fight against infections. Although previously thought to mediate protection solely in the extracellular environment, recent research has revealed that antibody-mediated protection extends to the cytosolic compartment of cells. This postentry viral defense mechanism requires binding of the antibody to a cytosolic Fc receptor named tripartite motif containing 21 (TRIM21). In contrast to other Fc receptors, TRIM21 shows remarkably broad isotype specificity as it does not only bind IgG but also IgM and IgA. When viral pathogens coated with these antibody isotypes enter the cytosol, TRIM21 is rapidly recruited and efficient neutralization occurs before the virus has had the time to replicate. In addition, inflammatory signaling is induced. As such, TRIM21 acts as a cytosolic sensor that engages antibodies that have failed to protect against infection in the extracellular environment. Here, we summarize our current understanding of how TRIM21 orchestrates humoral immunity in the cytosolic environment.
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Affiliation(s)
- Stian Foss
- Centre for Immune Regulation (CIR) and Department of Biosciences, University of Oslo, Oslo, Norway.,CIR and Department of Immunology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Ruth Watkinson
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Inger Sandlie
- Centre for Immune Regulation (CIR) and Department of Biosciences, University of Oslo, Oslo, Norway.,CIR and Department of Immunology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Leo C James
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Jan Terje Andersen
- CIR and Department of Immunology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
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18
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Klaus T, Bzowska M, Kulesza M, Kabat AM, Jemioła-Rzemińska M, Czaplicki D, Makuch K, Jucha J, Karabasz A, Bereta J. Agglutinating mouse IgG3 compares favourably with IgMs in typing of the blood group B antigen: Functionality and stability studies. Sci Rep 2016; 6:30938. [PMID: 27484487 PMCID: PMC4971511 DOI: 10.1038/srep30938] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/11/2016] [Indexed: 12/24/2022] Open
Abstract
Mouse immunoglobulins M (IgMs) that recognize human blood group antigens induce haemagglutination and are used worldwide for diagnostic blood typing. Contrary to the current belief that IgGs are too small to simultaneously bind antigens on two different erythrocytes, we obtained agglutinating mouse IgG3 that recognized antigen B of the human ABO blood group system. Mouse IgG3 is an intriguing isotype that has the ability to form Fc-dependent oligomers. However, F(ab′)2 fragments of the IgG3 were sufficient to agglutinate type B red blood cells; therefore, IgG3-triggered agglutination did not require oligomerization. Molecular modelling indicated that mouse IgG3 has a larger range of Fab arms than other mouse IgG subclasses and that the unique properties of mouse IgG3 are likely due to the structure of its hinge region. With a focus on applications in diagnostics, we compared the stability of IgG3 and two IgMs in formulated blood typing reagents using an accelerated storage approach and differential scanning calorimetry. IgG3 was much more stable than IgMs. Interestingly, the rapid decrease in IgM activity was caused by aggregation of the molecules and a previously unknown posttranslational proteolytic processing of the μ heavy chain. Our data point to mouse IgG3 as a potent diagnostic tool.
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Affiliation(s)
- Tomasz Klaus
- Malopolska Centre of Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7A, 30-387 Kraków, Poland.,Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Monika Bzowska
- Malopolska Centre of Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7A, 30-387 Kraków, Poland.,Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Małgorzata Kulesza
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Agnieszka Martyna Kabat
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Małgorzata Jemioła-Rzemińska
- Malopolska Centre of Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7A, 30-387 Kraków, Poland.,Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Dominik Czaplicki
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Krzysztof Makuch
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Jarosław Jucha
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Alicja Karabasz
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
| | - Joanna Bereta
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387 Kraków, Poland
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19
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Agostino M, Mancera RL, Ramsland PA, Fernández-Recio J. Optimization of protein-protein docking for predicting Fc-protein interactions. J Mol Recognit 2016; 29:555-568. [PMID: 27445195 DOI: 10.1002/jmr.2555] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 06/12/2016] [Accepted: 06/14/2016] [Indexed: 01/08/2023]
Abstract
The antibody crystallizable fragment (Fc) is recognized by effector proteins as part of the immune system. Pathogens produce proteins that bind Fc in order to subvert or evade the immune response. The structural characterization of the determinants of Fc-protein association is essential to improve our understanding of the immune system at the molecular level and to develop new therapeutic agents. Furthermore, Fc-binding peptides and proteins are frequently used to purify therapeutic antibodies. Although several structures of Fc-protein complexes are available, numerous others have not yet been determined. Protein-protein docking could be used to investigate Fc-protein complexes; however, improved approaches are necessary to efficiently model such cases. In this study, a docking-based structural bioinformatics approach is developed for predicting the structures of Fc-protein complexes. Based on the available set of X-ray structures of Fc-protein complexes, three regions of the Fc, loosely corresponding to three turns within the structure, were defined as containing the essential features for protein recognition and used as restraints to filter the initial docking search. Rescoring the filtered poses with an optimal scoring strategy provided a success rate of approximately 80% of the test cases examined within the top ranked 20 poses, compared to approximately 20% by the initial unrestrained docking. The developed docking protocol provides a significant improvement over the initial unrestrained docking and will be valuable for predicting the structures of currently undetermined Fc-protein complexes, as well as in the design of peptides and proteins that target Fc.
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Affiliation(s)
- Mark Agostino
- School of Biomedical Sciences, Curtin Health Innovation Research Institute and Curtin Institute for Computation, Curtin University, Perth, Australia.,Joint BSC-CRG-IRB Research Program in Computational Biology, Life Sciences Department, Barcelona Supercomputing Center, Barcelona, Spain.,Centre for Biomedical Research, Burnet Institute, Melbourne, Australia
| | - Ricardo L Mancera
- School of Biomedical Sciences, Curtin Health Innovation Research Institute and Curtin Institute for Computation, Curtin University, Perth, Australia
| | - Paul A Ramsland
- Centre for Biomedical Research, Burnet Institute, Melbourne, Australia. .,School of Science, RMIT University, Bundoora, Australia. .,Department of Surgery Austin Health, University of Melbourne, Heidelberg, Australia. .,Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Australia.
| | - Juan Fernández-Recio
- Joint BSC-CRG-IRB Research Program in Computational Biology, Life Sciences Department, Barcelona Supercomputing Center, Barcelona, Spain.
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20
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21
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Translocalized IgA mediates neutralization and stimulates innate immunity inside infected cells. Proc Natl Acad Sci U S A 2014; 111:13463-8. [PMID: 25169018 DOI: 10.1073/pnas.1410980111] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
IgA is the most prevalent antibody type on mucosal surfaces and the second most prevalent antibody in circulation, yet its role in immune defense is not fully understood. Here we show that IgA is carried inside cells during virus infection, where it activates intracellular virus neutralization and innate immune signaling. Cytosolic IgA-virion complexes colocalize with the high-affinity antibody receptor tripartite motif-containing protein 21 (TRIM21) and are positive for lysine-48 ubiquitin chains. IgA neutralizes adenovirus infection in a TRIM21- and proteasome-dependent manner in both human and mouse cells. Translocated IgA also potently activates NF-κB signaling pathways in cells expressing TRIM21, whereas viral infection in the absence of antibody or TRIM21 is undetected. TRIM21 recognizes an epitope in IgG Fc that is not conserved in IgA; however, fluorescence anisotropy experiments demonstrate that direct binding to IgA is maintained. We use molecular modeling to show that TRIM21 forms a nonspecific hydrophobic seal around a β-loop structure that is present in IgG, IgM, and IgA, explaining how TRIM21 achieves such remarkable broad antibody specificity. The findings demonstrate that the antiviral protection afforded by IgA extends to the intracellular cytosolic environment.
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22
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Satake K, Shimizu Y, Sasaki Y, Yanagawa H, Suzuki H, Suzuki Y, Horikoshi S, Honda S, Shibuya K, Shibuya A, Tomino Y. Serum under-O-glycosylated IgA1 level is not correlated with glomerular IgA deposition based upon heterogeneity in the composition of immune complexes in IgA nephropathy. BMC Nephrol 2014; 15:89. [PMID: 24928472 PMCID: PMC4064268 DOI: 10.1186/1471-2369-15-89] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 06/09/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Although serum under-O-glycosylated IgA1 in IgA nephropathy (IgAN) patients may deposit more preferentially in glomeruli than heavily-O-glycosylated IgA1, the relationship between the glomerular IgA deposition level and the O-glycan profiles of serum IgA1 remains obscure. METHODS Serum total under-O-glycosylated IgA1 levels were quantified in 32 IgAN patients by an enzyme-linked immunosorbent assay (ELISA) with Helix aspersa (HAA) lectin. Serum under-O-glycosylated polymeric IgA1 (pIgA1) was selectively measured by an original method using mouse Fcα/μ receptor (mFcα/μR) transfectant and flow cytometry (pIgA1 trap). The percentage area of IgA deposition in the whole glomeruli (Area-IgA) was quantified by image analysis on the immunofluorescence of biopsy specimens. Correlations were assessed between the Area-IgA and data from HAA-ELISA or pIgA1 trap. The relationships between clinical parameters and data from HAA-ELISA or pIgA1 trap were analyzed by data mining approach. RESULTS While the under-O-glycosylated IgA1 levels in IgAN patients were significantly higher than those in healthy controls when measured (p<0.05), there was no significant difference in under-O-glycosylated pIgA1. There was neither a correlation observed between the data from HAA-ELISA and pIgA1 trap (r2=0.09) in the IgAN patients (r2=0.005) nor was there a linear correlation between Area-IgA and data from HAA-ELISA or the pIgA1 trap (r2=0.005, 0.03, respectively). Contour plots of clinical parameters versus data from HAA-ELISA and the pIgA1 trap revealed that patients with a high score in each clinical parameter concentrated in specific areas, showing that patients with specific O-glycan profiles of IgA1 have similar clinical parameters. A decision tree analysis suggested that dominant immune complexes in glomeruli were consisted of: 1) IgA1-IgG and complements, 2) pIgA1 and complements, and 3) monomeric IgA1-IgA or aggregated monomeric IgA1. CONCLUSIONS Serum under-O-glycosylated IgA1 levels are not correlated with glomerular IgA deposition based upon heterogeneity in the composition of glomerular immune complexes in IgAN patients.
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Affiliation(s)
| | - Yoshio Shimizu
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
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23
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Pinheiro A, Woof JM, Abi-Rached L, Parham P, Esteves PJ. Computational analyses of an evolutionary arms race between mammalian immunity mediated by immunoglobulin A and its subversion by bacterial pathogens. PLoS One 2013; 8:e73934. [PMID: 24019941 PMCID: PMC3760800 DOI: 10.1371/journal.pone.0073934] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 07/26/2013] [Indexed: 12/19/2022] Open
Abstract
IgA is the predominant immunoglobulin isotype in mucosal tissues and external secretions, playing important roles both in defense against pathogens and in maintenance of commensal microbiota. Considering the complexity of its interactions with the surrounding environment, IgA is a likely target for diversifying or positive selection. To investigate this possibility, the action of natural selection on IgA was examined in depth with six different methods: CODEML from the PAML package and the SLAC, FEL, REL, MEME and FUBAR methods implemented in the Datamonkey webserver. In considering just primate IgA, these analyses show that diversifying selection targeted five positions of the Cα1 and Cα2 domains of IgA. Extending the analysis to include other mammals identified 18 positively selected sites: ten in Cα1, five in Cα2 and three in Cα3. All but one of these positions display variation in polarity and charge. Their structural locations suggest they indirectly influence the conformation of sites on IgA that are critical for interaction with host IgA receptors and also with proteins produced by mucosal pathogens that prevent their elimination by IgA-mediated effector mechanisms. Demonstrating the plasticity of IgA in the evolution of different groups of mammals, only two of the eighteen selected positions in all mammals are included in the five selected positions in primates. That IgA residues subject to positive selection impact sites targeted both by host receptors and subversive pathogen ligands highlights the evolutionary arms race playing out between mammals and pathogens, and further emphasizes the importance of IgA in protection against mucosal pathogens.
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Affiliation(s)
- Ana Pinheiro
- CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos/InBio Laboratório Associado, Universidade do Porto, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- SaBio - Instituto de Investigación en Recursos Cinegéticos (CSIC-UCLM-JCCM), Ciudad Real, Spain
| | - Jenny M. Woof
- Division of Cancer Research, Medical Research Institute, University of Dundee Medical School, Ninewells Hospital, Dundee, United Kingdom
| | - Laurent Abi-Rached
- Centre National de la Recherche Scientifique, Laboratoire d’Analyse, Topologie, Probabilités - Unité Mixte de Recherche 7353, Equipe ATIP, Aix-Marseille Université, Marseille, France
| | - Peter Parham
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Pedro J. Esteves
- CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos/InBio Laboratório Associado, Universidade do Porto, Vairão, Portugal
- CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Gandra PRD, Portugal
- * E-mail:
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24
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Yang X, Zhao Q, Zhu L, Zhang W. The three complementarity-determining region-like loops in the second extracellular domain of human Fc alpha/mu receptor contribute to its binding of IgA and IgM. Immunobiology 2013. [DOI: 10.1016/j.imbio.2012.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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25
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Wines BD, Trist HM, Farrugia W, Ngo C, Trowsdale J, Areschoug T, Lindahl G, Fraser JD, Ramsland PA. A conserved host and pathogen recognition site on immunoglobulins: structural and functional aspects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 946:87-112. [PMID: 21948364 DOI: 10.1007/978-1-4614-0106-3_6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A common site in the constant region (Fc) of immunoglobulins is recognized by host receptors and is a frequent target of proteins expressed by pathogens. This site is located at the junction of two constant domains in the antibody heavy chains and produces a large shallow cavity formed by loops of the CH2 and CH3 domains in IgG and IgA (CH3 and CH4 domains in IgM). Crystal structures have been determined for complexes of IgG-Fc and IgA-Fc with a structurally diverse set of host, pathogen and in vitro selected ligands. While pathogen proteins may directly block interactions with the immunoglobulins thereby evading host immunity, it is likely that the same pathogen molecules also interact with other host factors to carry out their primary biological function. Herein we review the structural and functional aspects of host and pathogen molecular recognition of the common site on the Fc of immunoglobulins. We also propose that some pathogen proteins may promote virulence by affecting the bridging between innate and adaptive immunity.
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Affiliation(s)
- Bruce D Wines
- Centre for Immunology, Burnet Institute, Melbourne, VIC 3004, Australia.
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26
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Tadiso TM, Sharma A, Hordvik I. Analysis of polymeric immunoglobulin receptor- and CD300-like molecules from Atlantic salmon. Mol Immunol 2011; 49:462-73. [DOI: 10.1016/j.molimm.2011.09.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 09/19/2011] [Accepted: 09/20/2011] [Indexed: 12/25/2022]
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27
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Abstract
Immunoglobulin A (IgA) has a critical role in immune defense particularly at the mucosal surfaces, and is equipped to do so by the unique structural attributes of its heavy chain and by its ability to polymerize. Here, we provide an overview of human IgA structure, describing the distinguishing features of the IgA1 and IgA2 subclasses and mapping the sites of interaction with host receptors important for IgA's functional repertoire. Remarkably, these same interaction sites are targeted by binding proteins and proteases produced by various pathogens as a means to subvert the protective IgA response. As interest in the prospect of therapeutic IgA-based monoclonal antibodies grows, the emerging understanding of the relationship between IgA structure and function will be invaluable for maximizing the potential of these novel reagents.
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Affiliation(s)
- J M Woof
- Medical Research Institute, University of Dundee Medical School, Dundee, UK.
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28
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Klimovich VB. IgM and its receptors: structural and functional aspects. BIOCHEMISTRY (MOSCOW) 2011; 76:534-49. [PMID: 21639833 DOI: 10.1134/s0006297911050038] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review combines the data obtained before the beginning of the 1990s with results published during the last two decades. The predominant form of the IgM molecule is a closed ring composed of five 7S subunits and a J chain. The new model of spatial structure of the pentamer postulates nonplanar mushroom-shaped form of the molecule with the plane formed by a radially-directed Fab regions and central protruding portion consisting of Cµ4 domains. Up to the year 2000 the only known Fc-receptor for IgM was pIgR. Interaction of IgM with pIgR results in secretory IgM formation, whose functions are poorly studied. The receptor designated as Fcα/µR is able to bind IgM and IgA. It is expressed on lymphocytes, follicular dendritic cells, and macrophages. A receptor binding IgM only named FcµR has also been described. It is expressed on T- and B-lymphocytes. The discovery of new Fc-receptors for IgM requires revision of notions that interactions between humoral reactions involving IgM and the cells of the immune system are mediated exclusively by complement receptors. In the whole organism, apart from IgM induced by immunization, natural antibodies (NA) are present and comprise in adults a considerable part of the circulating IgM. NA are polyreactive, germ-line-encoded, and emerge during embryogenesis without apparent antigenic stimuli. They demonstrate a broad spectrum of antibacterial activity and serve as first line of defense against microbial and viral infections. NA may be regarded as a transitional molecular form from invariable receptors of innate immunity to highly diverse receptors of adaptive immunity. By means of interaction with autoantigens, NA participate in maintenance of immunological tolerance and in clearance of dying cells. At the same time, NA may act as a pathogenic factor in atherosclerotic lesion formation and in development of tissue damage due to ischemia/reperfusion.
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Affiliation(s)
- V B Klimovich
- Russian Research Center for Radiology and Surgical Technologies, St. Petersburg.
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29
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Ramsland PA, Farrugia W, Bradford TM, Tan Sardjono C, Esparon S, Trist HM, Powell MS, Szee Tan P, Cendron AC, Wines BD, Scott AM, Hogarth PM. Structural basis for Fc gammaRIIa recognition of human IgG and formation of inflammatory signaling complexes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 187:3208-17. [PMID: 21856937 PMCID: PMC3282893 DOI: 10.4049/jimmunol.1101467] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The interaction of Abs with their specific FcRs is of primary importance in host immune effector systems involved in infection and inflammation, and are the target for immune evasion by pathogens. FcγRIIa is a unique and the most widespread activating FcR in humans that through avid binding of immune complexes potently triggers inflammation. Polymorphisms of FcγRIIa (high responder/low responder [HR/LR]) are linked to susceptibility to infections, autoimmune diseases, and the efficacy of therapeutic Abs. In this article, we define the three-dimensional structure of the complex between the HR (arginine, R134) allele of FcγRIIa (FcγRIIa-HR) and the Fc region of a humanized IgG1 Ab, hu3S193. The structure suggests how the HR/LR polymorphism may influence FcγRIIa interactions with different IgG subclasses and glycoforms. In addition, mutagenesis defined the basis of the epitopes detected by FcR blocking mAbs specific for FcγRIIa (IV.3), FcγRIIb (X63-21), and a pan FcγRII Ab (8.7). The epitopes detected by these Abs are distinct, but all overlap with residues defined by crystallography to contact IgG. Finally, crystal structures of LR (histidine, H134) allele of FcγRIIa and FcγRIIa-HR reveal two distinct receptor dimers that may represent quaternary states on the cell surface. A model is presented whereby a dimer of FcγRIIa-HR binds Ag-Ab complexes in an arrangement that possibly occurs on the cell membrane as part of a larger signaling assembly.
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Affiliation(s)
- Paul A. Ramsland
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia,Department of Surgery, Austin Hospital, University of Melbourne, Heidelberg, Victoria 3084, Australia,Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia
| | - William Farrugia
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Tessa M. Bradford
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia
| | | | - Sandra Esparon
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Halina M. Trist
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Maree S. Powell
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia,Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia,Department of Pathology, University of Melbourne, Parkville, Victoria 3056, Australia
| | - Peck Szee Tan
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Angela C. Cendron
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Bruce D. Wines
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia,Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia,Department of Pathology, University of Melbourne, Parkville, Victoria 3056, Australia
| | - Andrew M. Scott
- Tumour Targeting Program, Ludwig Institute for Cancer Research, Austin Health, Heidelberg, Victoria 3084, Australia
| | - P. Mark Hogarth
- Centre for Immunology, Burnet Institute, Melbourne, Victoria 3004, Australia,Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia,Department of Pathology, University of Melbourne, Parkville, Victoria 3056, Australia
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30
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Yoo EM, Trinh KR, Lim H, Wims LA, Morrison SL. Characterization of IgA and IgM binding and internalization by surface-expressed human Fcα/μ receptor. Mol Immunol 2011; 48:1818-26. [DOI: 10.1016/j.molimm.2011.05.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 05/09/2011] [Indexed: 10/18/2022]
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Fabrizio K, Manix C, Tian H, van Rooijen N, Pirofski LA. The efficacy of pneumococcal capsular polysaccharide-specific antibodies to serotype 3 Streptococcus pneumoniae requires macrophages. Vaccine 2010; 28:7542-50. [PMID: 20800700 DOI: 10.1016/j.vaccine.2010.08.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/01/2010] [Accepted: 08/12/2010] [Indexed: 10/19/2022]
Abstract
The efficacy of antibody immunity against Streptococcus pneumoniae stems from the ability of opsonic, serotype (ST)-specific antibodies to pneumococcal capsular polysaccharide (PPS) to facilitate killing of the homologous ST by host phagocytes. However, PPS-specific antibodies have been identified that are protective in mice, but do not promote opsonic killing in vitro, raising the question of how they mediate protection in vivo. To probe this question, we investigated the dependence of antibody efficacy against lethal systemic (intraperitoneal, i.p.) infection with Streptococcus pneumoniae serotype 3 (ST3) on macrophages and neutrophils for the following PPS3-specific monoclonal antibodies (MAbs) in survival experiments in mice using a non-opsonic human IgM (A7), a non-opsonic mouse IgG1 (1E2) and an opsonic mouse IgG1 (5F6). The survival of A7- and PPS3-specific and isotype control MAb-treated neutrophil-depleted and neutrophil-sufficient and macrophage-depleted and macrophage-sufficient mice were determined after i.p. challenge with ST3 strains 6303 and WU2. Neutrophils were dispensable for A7 and the mouse MAbs to mediate protection in this model, but macrophages were required for the efficacy of A7 and optimal mouse MAb-mediated protection. For A7-treated mice, macrophage-depleted mice had higher blood CFU, cytokines and peripheral neutrophil levels than macrophage-sufficient mice, and macrophage-sufficient mice had lower tissue bacterial burdens than control MAb-treated mice. These findings demonstrate that macrophages contribute to opsonic and non-opsonic PPS3-specific MAb-mediated protection against ST3 infection by enhancing bacterial clearance and suggest that neutrophils do not compensate for the absence of macrophages in the model used in this study.
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Affiliation(s)
- Kevin Fabrizio
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Czajkowsky DM, Salanti A, Ditlev SB, Shao Z, Ghumra A, Rowe JA, Pleass RJ. IgM, Fc mu Rs, and malarial immune evasion. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2010; 184:4597-603. [PMID: 20410497 PMCID: PMC2859470 DOI: 10.4049/jimmunol.1000203] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
IgM is an ancestral Ab class found in all jawed vertebrates, from sharks to mammals. This ancient ancestry is shared by malaria parasites (genus Plasmodium) that infect all classes of terrestrial vertebrates with whom they coevolved. IgM, the least studied and most enigmatic of the vertebrate Igs, was recently shown to form an intimate relationship with the malaria parasite Plasmodium falciparum. In this article, we discuss how this association might have come about, building on the recently determined structure of the human IgM pentamer, and how this interaction could affect parasite survival, particularly in light of the just-discovered Fc mu R localized to B and T cell surfaces. Because this parasite may exploit an interaction with IgM to limit immune detection, as well as to manipulate the immune response when detected, a better understanding of this association may prove critical for the development of improved vaccines or vaccination strategies.
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Affiliation(s)
- Daniel M. Czajkowsky
- Department of Molecular Physiology & Biological Physics, University of Virginia Health Sciences Center, P. O. Box 800736, Charlottesville, VA 22908, USA
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, China
| | - Ali Salanti
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen, Copenhagen University Hospital, Rigshospitalet, DK
| | - Sisse B Ditlev
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen, Copenhagen University Hospital, Rigshospitalet, DK
| | - Zhifeng Shao
- Department of Molecular Physiology & Biological Physics, University of Virginia Health Sciences Center, P. O. Box 800736, Charlottesville, VA 22908, USA
- MOE Key Lab for Systems Biomedicine and National Lab for Oncogenes, Shanghai JiaoTong University, Shanghai 200240, China
| | - Ashfaq Ghumra
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, UK
- Institute of Genetics, and Parasite Biology and Immunogenetics Research Group, Queen’s Medical Centre, University of Nottingham, NG7 2UH, UK
| | - J. Alexandra Rowe
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, UK
| | - Richard J Pleass
- Institute of Genetics, and Parasite Biology and Immunogenetics Research Group, Queen’s Medical Centre, University of Nottingham, NG7 2UH, UK
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Aggregation of Streptococcus pneumoniae by a pneumococcal capsular polysaccharide-specific human monoclonal IgM correlates with antibody efficacy in vivo. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:713-21. [PMID: 20200186 DOI: 10.1128/cvi.00410-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Acquired antibody immunity to Streptococcus pneumoniae (pneumococcus) has been linked to serotype (ST)-specific opsonic antibodies to the relevant pneumococcal capsular polysaccharide (PPS) that mediate protection by enhancing the bactericidal effect of host phagocytes. Despite the well-recognized role of opsonic IgG in host defense against pneumococcus, PPS-specific monoclonal antibodies (MAbs) that mediate protection against lethal challenge with ST3 pneumococcus in mice but do not promote phagocytic killing in vitro (nonopsonic antibodies) have been described. In this study, we sought to determine the biological activity of one such MAb, A7 (a human PPS3-specific IgM), and the mechanism by which it mediates protection. In vitro studies demonstrated that coincubation of A7 with ST3 in the absence of phagocytes or a complement source resulted in a reduction in CFU on blood agar plates that was largely reversible by sonication. A chromogenic cellular proliferation assay demonstrated that A7 did not affect replication of ST3 in liquid culture. The ability of A7 to induce aggregation of ST3 was confirmed by fluorescence microscopy and flow cytometry: A7 induced aggregation of ST3, and in the presence of a complement source, A7 promoted deposition of complement component 3 (C3) on aggregated bacteria in a dose-dependent fashion. Similarly, administration of preincubated mixtures of A7 and ST3 intraperitoneally to mice protected them from the lethality of ST3 in a dose-dependent fashion. These findings suggest that A7-mediated aggregation enhances resistance to ST3, most likely by enhancing C3 deposition on the ST3 capsule, thereby promoting host antipneumococcal activity in vivo.
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Nayak DK, Tang A, Wilson M, Miller NW, Bengtén E. Channel catfish soluble FcmuR binds conserved linear epitopes present on Cmu3 and Cmu4. Mol Immunol 2010; 47:1306-16. [PMID: 20031218 PMCID: PMC2830281 DOI: 10.1016/j.molimm.2009.11.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 11/16/2009] [Accepted: 11/21/2009] [Indexed: 01/30/2023]
Abstract
A linear epitope on catfish IgM has been identified as the docking site for the catfish soluble FcmuR (IpFcRI). Western blot analyses and latex bead binding assays identified the consensus octapeptide motif FxCxVxHE located at the second cysteine that forms the intrachain disulfide bond of the catfish Cmu3 and Cmu4 immunolglobulin (Ig) domains as the IpFcRI binding sites. Furthermore, molecular modeling of catfish Cmu3 and Cmu4 confirmed that the octapeptide in both of these domains is accessible for IpFcRI interactions. In addition, since this octapeptide motif is also found in other vertebrate Ig domains, IpFcRI binding to Ig heavy (H) and light (L) chains from rainbow trout, chicken, mouse, rabbit, and goat were examined by Western blot analyses and latex bead binding assays. IpFcRI readily bound reduced rainbow trout (Igmu), chicken (Ignu), mouse (Igmu, Iggamma1, Iggamma2a, Iggamma2b, and Igalpha), rabbit (Igmu and Iggamma) and goat (Iggamma) IgH chains, and mouse Igkappa and Iglambda, and chicken Iglambda IgL chains. IpFcRI also bound mouse IgM, IgA and IgG subclasses when examined under native conditions.
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Affiliation(s)
- Deepak K. Nayak
- Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson MS, 39216, USA
| | - Aihua Tang
- Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson MS, 39216, USA
| | - Melanie Wilson
- Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson MS, 39216, USA
| | - Norman W. Miller
- Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson MS, 39216, USA
| | - Eva Bengtén
- Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson MS, 39216, USA
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Abstract
The complexity and number of antigens (Ags) seen during an immune response has hampered the development of malaria vaccines. Antibodies (Abs) play an important role in immunity to malaria and their passive administration is effective at controlling the disease. Abs represent approximately 25% of all proteins undergoing clinical trials, and these 'smart biologicals' have undergone a major revival with the realization that Abs lie at the interface between innate and adaptive immunity. At least 18 Abs have FDA approval for clinical use and approximately 150 are in clinical trials, the majority for the treatment of cancer, allograft rejection or autoimmune disease. Despite these triumphs none are in development for malaria, principally because they are perceived as being too expensive for a disease mainly afflicting poor and marginalized populations. Although unlikely, at least in the foreseeable future, that Ab-based prophylaxis will be made available to the millions of people at risk from malaria, they may be incorporated into current vaccine approaches, since Abs act as correlates of protection in studies aimed at defining the best Ags to include in vaccines. Abs may also form the basis for novel vaccination strategies by targeting Ags to appropriate antigen presenting cells. Therefore, to develop the most efficacious vaccines it will be necessary to fully understand which Abs and Fc-receptors (FcRs) are best engaged for a positive outcome.
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Affiliation(s)
- R J Pleass
- Institute of Genetics, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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Pürzel J, Schmitt R, Viertlboeck BC, Göbel TW. Chicken IgY binds its receptor at the CH3/CH4 interface similarly as the human IgA: Fc alpha RI interaction. THE JOURNAL OF IMMUNOLOGY 2009; 183:4554-9. [PMID: 19748988 DOI: 10.4049/jimmunol.0901699] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chicken IgY, the ancestral form of mammalian IgE and IgG, is recognized by the high-affinity FcY receptor CHIR-AB1, a member of the leukocyte receptor family. In this study, we have characterized the receptor ligand interaction site by consecutive truncations of the Fcv IgY domains and mutational analyses of selected residues. Using several fusion proteins that linked the human Cgamma2 and Cgamma3 domains with the Fcv IgY domains, a binding assay revealed that both the Fcv3 and Fcv4 domains were essential for the IgY CHIR-AB1 interaction. Sequence comparisons of chicken IgY with human IgA demonstrated that 11 of the 19 contact residues important for the IgA FcalphaRI interaction have been conserved in chicken IgY, although the overall amino acid identity is only 34%. Among the 19 amino acids at respective positions in IgY, the mutation of two residues in the Fcv3 and two in the Fcv4 domain completely abolished the IgY to CHIR-AB1 binding revealed by two independent assays. Three further mutations substantially altered the interaction. Molecular modeling on the Cv3 to Cv4 crystal structure revealed that all critical residues, although on two domains, are in close proximity. The importance of N-linked carbohydrates was demonstrated by the failure of the CHIR-AB1 interaction after mutation of the glycosylation site. The identification of the IgY Cv3/Cv4 interdomain region as critical for binding to CHIR-AB1 significantly enhances our understanding of the IgY receptor interaction and allows further conclusions regarding the FcR phylogeny.
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Affiliation(s)
- Jana Pürzel
- Department of Veterinary Sciences, University of Munich, Munich, Germany
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Sander AF, Salanti A, Lavstsen T, Nielsen MA, Magistrado P, Lusingu J, Ndam NT, Arnot DE. Multiple var2csa-type PfEMP1 genes located at different chromosomal loci occur in many Plasmodium falciparum isolates. PLoS One 2009; 4:e6667. [PMID: 19690615 PMCID: PMC2723927 DOI: 10.1371/journal.pone.0006667] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 07/13/2009] [Indexed: 12/03/2022] Open
Abstract
Background The var2csa gene encodes a Plasmodium falciparum adhesion receptor which binds chondroitin sulfate A (CSA). This var gene is more conserved than other PfEMP1/var genes and is found in all P. falciparum isolates. In isolates 3D7, FCR3/It4 and HB3, var2csa is transcribed from a sub-telomeric position on the left arm of chromosome 12, but it is not known if this location is conserved in all parasites. Genome sequencing indicates that the var2csa gene is duplicated in HB3, but whether this is true in natural populations is uncertain. Methodology/Principal Findings To assess global variation in the VAR2CSA protein, sequence variation in the DBL2X region of var2csa genes in 54 P.falciparum samples was analyzed. Chromosome mapping of var2csa loci was carried out and a quantitative PCR assay was developed to estimate the number of var2csa genes in P.falciparum isolates from the placenta of pregnant women and from the peripheral circulation of other malaria patients. Sequence analysis, gene mapping and copy number quantitation in P.falciparum isolates indicate that there are at least two loci and that both var2csa-like genes can be transcribed. All VAR2CSA DBL2X domains fall into one of two distinct phylogenetic groups possessing one or the other variant of a large (∼26 amino acid) dimorphic motif, but whether either motif variant is linked to a specific locus is not known. Conclusions/Significance Two or more related but distinct var2csa-type PfEMP1/var genes exist in many P. falciparum isolates. One gene is on chromosome 12 but additional var2csa-type genes are on different chromosomes in different isolates. Multiplicity of var2csa genes appears more common in infected placentae than in samples from non-pregnant donors indicating a possible advantage of this genotype in pregnancy associated malaria.
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Affiliation(s)
- Adam F. Sander
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Morten A. Nielsen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Pamela Magistrado
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- JMP-ENRICA Project, National Institute for Medical Research, Korogwe Laboratory, Tanga, Tanzania
| | - John Lusingu
- JMP-ENRICA Project, National Institute for Medical Research, Korogwe Laboratory, Tanga, Tanzania
| | - Nicaise Tuikue Ndam
- Institut de Recherche pour le Developpment, UR010, Universite Paris Descartes, Paris, France
| | - David E. Arnot
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen & Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- Institute of Immunology & Infection Research, School of Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- * E-mail:
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Pleass RJ. Do Escherichia coli express Fc-receptors for immunoglobulin? Mol Immunol 2009; 46:2439-40. [DOI: 10.1016/j.molimm.2009.04.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 04/16/2009] [Indexed: 10/20/2022]
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Cytoplasmic domain of human Fcalpha/mu receptor is required for ligand internalization. Cell Immunol 2009; 258:78-82. [PMID: 19393604 DOI: 10.1016/j.cellimm.2009.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Revised: 03/21/2009] [Accepted: 03/25/2009] [Indexed: 11/21/2022]
Abstract
The Fcalpha/mu receptor (Fcalpha/microR), a type I transmembrane protein, is an immunoglobulin Fc receptor for both IgA and IgM. Its functions in immune defense are not clear at present. In this work, human Fcalpha/microR was expressed in CHO, 293T, and COS-7 cells to study its biochemical functions. Fcalpha/microR expressed by CHO and 293T was only in monomer form in cytoplasma and the monomeric receptor could not bind IgA or IgM. In comparison, Fcalpha/microR expressed by COS-7 cells had both monomer and dimer forms. The binding assay showed that Fcalpha/microR expressed by COS-7 cells could bind IgM strongly and IgA weakly, implying that dimeric receptor could be expressed on cell membrane and functioned. The bound IgM could be internalized and the internalization was abolished when the cytoplasmic domain of Fcalpha/microR was truncated. Therefore, the cytoplasmic portion of human Fcalpha/microR is required in the internalization.
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