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Cuhaci U, Caglar K. Establishment of a method to detect human immunoglobulin G1 binding microorganisms. Diagn Microbiol Infect Dis 2023; 107:116019. [PMID: 37619441 DOI: 10.1016/j.diagmicrobio.2023.116019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 06/11/2023] [Accepted: 07/08/2023] [Indexed: 08/26/2023]
Abstract
In this study, we developed an original and rapid anti-idiotypic antibody-based ELISA method, different from the techniques defined in the literature for this purpose so far, to detect immunoglobulin binding proteins (IBP) on the surface of bacteria. The test antibody used in our study to detect IBP is a recombinant human immunoglobulin G1 Kappa molecule, and has been used as a drug, Tocilizumab (Actemra®), in humans for therapeutic purposes. As a result, the test antibody in the supernatant after centrifugation is reduced compared to the initial moment due to antibody binding. Staphylococcus aureus cowan 1 strain used as positive control causes at least a 50% decrease in OD value in this respect. A similar observation at this level indicated that among a total of 189 microorganisms tested, 3 Staphylococcus aureus and 1 MRSA carrying high-affinity IgBP showed greater than 50% inhibition. This level of inhibition was not detected in the remaining microorganisms.
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Affiliation(s)
- Ulker Cuhaci
- Faculty of Medicine, Department of Medical Microbiology, Yuksek İhtisas University, Ankara, Turkey; Faculty of Medicine, Department of Medical Microbiology, Gazi University, Ankara, Turkey.
| | - Kayhan Caglar
- Faculty of Medicine, Department of Medical Microbiology, Gazi University, Ankara, Turkey
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2
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Liu Q, Stadtmueller BM. SIgA structures bound to Streptococcus pyogenes M4 and human CD89 provide insights into host-pathogen interactions. Nat Commun 2023; 14:6726. [PMID: 37872175 PMCID: PMC10593759 DOI: 10.1038/s41467-023-42469-y] [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: 04/21/2023] [Accepted: 10/12/2023] [Indexed: 10/25/2023] Open
Abstract
Immunoglobulin (Ig) A functions as monomeric IgA in the serum and Secretory (S) IgA in mucosal secretions. Host IgA Fc receptors (FcαRs), including human FcαR1/CD89, mediate IgA effector functions; however, human pathogen Streptococcus pyogenes has evolved surface-protein virulence factors, including M4, that also engage the CD89-binding site on IgA. Despite human mucosa serving as a reservoir for pathogens, SIgA interactions with CD89 and M4 remain poorly understood. Here we report cryo-EM structures of M4-SIgA and CD89-SIgA complexes, which unexpectedly reveal different SIgA-binding stoichiometry for M4 and CD89. Structural data, supporting experiments, and modeling indicate that copies of SIgA bound to S. pyogenes M4 will adopt similar orientations on the bacterium surface and leave one host FcαR binding site open. Results suggest unappreciated functional consequences associated with SIgA binding to host and bacterial FcαRs relevant to understanding host-microbe co-evolution, IgA effector functions and improving the outcomes of group A Streptococcus infection.
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Affiliation(s)
- Qianqiao Liu
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Beth M Stadtmueller
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, 61801, USA.
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, 61801, USA.
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois, 61801, USA.
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3
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Liu Q, Stadtmueller BM. The Structures of Secretory IgA in complex with Streptococcus pyogenes M4 and human CD89 provide insights on mucosal host-pathogen interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.21.537878. [PMID: 37662389 PMCID: PMC10473612 DOI: 10.1101/2023.04.21.537878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Immunoglobulin (Ig) A functions as monomeric IgA in the serum and Secretory (S) IgA in mucosal secretions. Host IgA Fc receptors (FcαRs), including human FcαR1/CD89, mediate IgA effector functions; however human pathogen Streptococcus pyogenes has evolved surface-protein virulence factors, including M4, that also engage the CD89 binding site on IgA. Despite human mucosa serving as a reservoir for pathogens, SIgA interactions with CD89 and M4 remain poorly understood. Here we report cryo-EM structures of M4-SIgA and CD89-SIgA complexes, which unexpectedly reveal different SIgA-binding stoichiometry for M4 and CD89. Structural data, supporting experiments, and modeling indicate that copies of SIgA bound to S. pyogenes M4 will adopt similar orientations on the bacterium surface and leave one host FcαR binding site open. Results suggest unappreciated functional consequences associated with SIgA binding to host and bacterial FcαRs relevant to understanding host-microbe co-evolution, IgA effector functions and to improving the outcomes of group A Streptococcus infection.
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Affiliation(s)
- Qianqiao Liu
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Beth M Stadtmueller
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 USA
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 USA
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4
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Tissues: the unexplored frontier of antibody mediated immunity. Curr Opin Virol 2021; 47:52-67. [PMID: 33581646 DOI: 10.1016/j.coviro.2021.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/01/2021] [Accepted: 01/05/2021] [Indexed: 12/14/2022]
Abstract
Pathogen-specific immunity evolves in the context of the infected tissue. However, current immune correlates analyses and vaccine efficacy metrics are based on immune functions from peripheral cells. Less is known about tissue-resident mechanisms of immunity. While antibodies represent the primary correlate of immunity following most clinically approved vaccines, how antibodies interact with localized, compartment-specific immune functions to fight infections, remains unclear. Emerging data demonstrate a unique community of immune cells that reside within different tissues. These tissue-specific immunological communities enable antibodies to direct both expected and unexpected local attack strategies to control, disrupt, and eliminate infection in a tissue-specific manner. Defining the full breadth of antibody effector functions, how they selectively contribute to control at the site of infection may provide clues for the design of next-generation vaccines able to direct the control, elimination, and prevention of compartment specific diseases of both infectious and non-infectious etiologies.
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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: 111] [Impact Index Per Article: 22.2] [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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Bakshi S, Depicker A, Schepens B, Saelens X, Juarez P. A two-amino acid mutation in murine IgA enables downstream processing and purification on staphylococcal superantigen-like protein 7. J Biotechnol 2019; 294:26-29. [PMID: 30771443 DOI: 10.1016/j.jbiotec.2019.01.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 11/20/2022]
Abstract
With few exceptions, all currently marketed antibody therapeutics are IgG molecules. One of the reasons that other antibody isotypes are less developed are the difficulties associated with their purification. While commercial chromatography affinity resins, like staphylococcal superantigen-like 7 (SSL7) protein-containing resin, allow purification of IgAs from many animal species, these are not useful for murine IgAs. Because the mouse model is predominantly used for preclinical evaluation of IgA-based therapeutics, there is a need to develop an effective purification method for mouse IgA. Here, we adapted the sequence of a mouse IgA by mutating two amino acid residues in the fragment crystallizable (Fc) sequence to facilitate its purification on SSL7 resin. The mutated IgA Fc (hereafter referred to as IgA*) was then genetically fused to the variable domain of a llama heavy chain-only antibody (VHH) directed against the fusion protein of human respiratory syncytial virus (HRSV), resulting in VHH-IgA*, and transiently produced in infiltrated Nicotiana benthamiana leaves. These plant-produced mouse VHH-IgA* fusions were enriched by SSL7 affinity chromatography and were found to be functional in ELISA and could neutralize RSV in vitro, suggesting no detrimental effect of the mutation on their antigen-binding properties. This approach for the purification of murine IgA will facilitate downstream processing steps when designing innovative murine IgA-based fusions.
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Affiliation(s)
- Shruti Bakshi
- Ghent University, Department of Plant Biotechnology and Bioinformatics, and VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Ann Depicker
- Ghent University, Department of Plant Biotechnology and Bioinformatics, and VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Bert Schepens
- Ghent University, Department of Biomedical Molecular Biology, and VIB Center for Medical Biotechnology, 9052, Ghent, Belgium
| | - Xavier Saelens
- Ghent University, Department of Biomedical Molecular Biology, and VIB Center for Medical Biotechnology, 9052, Ghent, Belgium; Ghent University, Department of Biochemistry and Microbiology, 9052 Ghent, Belgium
| | - Paloma Juarez
- Ghent University, Department of Plant Biotechnology and Bioinformatics, and VIB Center for Plant Systems Biology, 9052 Ghent, Belgium; Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC), Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain.
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Enterococcus faecalis Promotes Innate Immune Suppression and Polymicrobial Catheter-Associated Urinary Tract Infection. Infect Immun 2017; 85:IAI.00378-17. [PMID: 28893918 DOI: 10.1128/iai.00378-17] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 09/01/2017] [Indexed: 12/18/2022] Open
Abstract
Enterococcus faecalis, a member of the human gastrointestinal microbiota, is an opportunistic pathogen associated with hospital-acquired wound, bloodstream, and urinary tract infections. E. faecalis can subvert or evade immune-mediated clearance, although the mechanisms are poorly understood. In this study, we examined E. faecalis-mediated subversion of macrophage activation. We observed that E. faecalis actively prevents NF-κB signaling in mouse RAW264.7 macrophages in the presence of Toll-like receptor agonists and during polymicrobial infection with Escherichia coliE. faecalis and E. coli coinfection in a mouse model of catheter-associated urinary tract infection (CAUTI) resulted in a suppressed macrophage transcriptional response in the bladder compared to that with E. coli infection alone. Finally, we demonstrated that coinoculation of E. faecalis with a commensal strain of E. coli into catheterized bladders significantly augmented E. coli CAUTI. Taken together, these results support the hypothesis that E. faecalis suppression of NF-κB-driven responses in macrophages promotes polymicrobial CAUTI pathogenesis, especially during coinfection with less virulent or commensal E. coli strains.
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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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10
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Fevre C, Bestebroer J, Mebius MM, de Haas CJC, van Strijp JAG, Fitzgerald JR, Haas PJA. Staphylococcus aureus proteins SSL6 and SElX interact with neutrophil receptors as identified using secretome phage display. Cell Microbiol 2014; 16:1646-65. [PMID: 24840181 DOI: 10.1111/cmi.12313] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 12/20/2022]
Abstract
In order to cause colonization and invasive disease, pathogenic bacteria secrete proteins that modulate host immune defences. Identification and characterization of these proteins leads to a better understanding of the pathological processes underlying infectious and inflammatory diseases and is essential in the development of new strategies for their prevention and treatment. Current techniques to functionally characterize these proteins are laborious and inefficient. Here we describe a high-throughput functional selection strategy using phage display in order to identify immune evasion proteins. Using this technique we identified two previously uncharacterized proteins secreted by Staphylococcus aureus, SElX and SSL6 that bind to neutrophil surface receptors. SElX binds PSGL-1 on neutrophils and thereby inhibits the interaction between PSGL-1 and P-selectin, a crucial step in the recruitment of neutrophils to the site of infection. SSL6 is the first bacterial protein identified that binds CD47, a widely expressed cell surface protein recently described as an interesting target in anti-cancer therapy. Our findings provide new insights into the pathogenesis of S. aureus infections and support phage display as an efficient method to identify bacterial secretome proteins interacting with humoral or cellular immune components.
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Affiliation(s)
- Cindy Fevre
- Department of Medical Microbiology, University Medical Center Utrecht, PO G04.614, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
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Bröker BM, Holtfreter S, Bekeredjian-Ding I. Immune control of Staphylococcus aureus – Regulation and counter-regulation of the adaptive immune response. Int J Med Microbiol 2014; 304:204-14. [DOI: 10.1016/j.ijmm.2013.11.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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12
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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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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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14
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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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Wines BD, Ramsland PA, Trist HM, Gardam S, Brink R, Fraser JD, Hogarth PM. Interaction of human, rat, and mouse immunoglobulin A (IgA) with Staphylococcal superantigen-like 7 (SSL7) decoy protein and leukocyte IgA receptor. J Biol Chem 2011; 286:33118-24. [PMID: 21784854 PMCID: PMC3190891 DOI: 10.1074/jbc.m111.272252] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 07/17/2011] [Indexed: 11/06/2022] Open
Abstract
Host survival depends on an effective immune system and pathogen survival on the effectiveness of immune evasion mechanisms. Staphylococcus aureus utilizes a number of molecules to modulate host immunity, including the SSL family of which SSL7 binds IgA and inhibits Fcα receptor I (FcαRI)-mediated function. Other Gram-positive bacterial pathogens produce IgA binding proteins, which, similar to SSL7, also bind the Fc at the CH2/CH3 interface (the junction between constant domains 2 and 3 of the heavy chain). The opposing activities of the host FcαRI-IgA receptor ligand pair and the pathogen decoy proteins select for host and pathogen variants, which exert stronger protection or evasion, respectively. Curiously, mouse but not rat IgA contains a putative N-linked glycosylation site in the center of this host receptor and pathogen-binding site. Here, we demonstrate that this site is glycosylated and that the effect of amino acid changes and glycosylation of the CH2/CH3 interface inhibits interaction with the pathogen IgA binding protein SSL7, while maintaining binding of pIgR, essential to the biosynthesis and transport of SIgA.
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Affiliation(s)
- Bruce D. Wines
- From the Centre for Immunology, The Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia
| | - Paul A. Ramsland
- From the Centre for Immunology, The Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia
| | - Halina M. Trist
- From the Centre for Immunology, The Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia
| | - Sandra Gardam
- the Immunology Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst 2010, Australia, and
| | - Robert Brink
- the Immunology Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst 2010, Australia, and
| | - John D. Fraser
- the Maurice Wilkins Centre and School of Medical Sciences, The University of Auckland, Auckland 1020, New Zealand
| | - P. Mark Hogarth
- From the Centre for Immunology, The Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia
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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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17
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Benson MA, Lilo S, Wasserman GA, Thoendel M, Smith A, Horswill AR, Fraser J, Novick RP, Shopsin B, Torres VJ. Staphylococcus aureus regulates the expression and production of the staphylococcal superantigen-like secreted proteins in a Rot-dependent manner. Mol Microbiol 2011; 81:659-75. [PMID: 21651625 DOI: 10.1111/j.1365-2958.2011.07720.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Staphylococcus aureus overproduces a subset of immunomodulatory proteins known as the staphylococcal superantigen-like proteins (Ssls) under conditions of pore-mediated membrane stress. In this study we demonstrate that overproduction of Ssls during membrane stress is due to the impaired activation of the two-component module of the quorum-sensing accessory gene regulator (Agr) system. Agr-dependent repression of ssl expression is indirect and mediated by the transcription factor repressor of toxins (Rot). Surprisingly, we observed that Rot directly interacts with and activates the ssl promoters. The role of Agr and Rot as regulators of ssl expression was observed across several clinically relevant strains, suggesting that overproduction of immunomodulatory proteins benefits agr-defective strains. In support of this notion, we demonstrate that Ssls contribute to the residual virulence of S. aureus lacking agr in a murine model of systemic infection. Altogether, these results suggest that S. aureus compensates for the inactivation of Agr by producing immunomodulatory exoproteins that could protect the bacterium from host-mediated clearance.
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Affiliation(s)
- Meredith A Benson
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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Argudín MÁ, Mendoza MC, Rodicio MR. Food poisoning and Staphylococcus aureus enterotoxins. Toxins (Basel) 2010; 2:1751-73. [PMID: 22069659 PMCID: PMC3153270 DOI: 10.3390/toxins2071751] [Citation(s) in RCA: 609] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/24/2010] [Accepted: 06/30/2010] [Indexed: 01/31/2023] Open
Abstract
Staphylococcus aureus produces a wide variety of toxins including staphylococcal enterotoxins (SEs; SEA to SEE, SEG to SEI, SER to SET) with demonstrated emetic activity, and staphylococcal-like (SEl) proteins, which are not emetic in a primate model (SElL and SElQ) or have yet to be tested (SElJ, SElK, SElM to SElP, SElU, SElU2 and SElV). SEs and SEls have been traditionally subdivided into classical (SEA to SEE) and new (SEG to SElU2) types. All possess superantigenic activity and are encoded by accessory genetic elements, including plasmids, prophages, pathogenicity islands, vSa genomic islands, or by genes located next to the staphylococcal cassette chromosome (SCC) implicated in methicillin resistance. SEs are a major cause of food poisoning, which typically occurs after ingestion of different foods, particularly processed meat and dairy products, contaminated with S. aureus by improper handling and subsequent storage at elevated temperatures. Symptoms are of rapid onset and include nausea and violent vomiting, with or without diarrhea. The illness is usually self-limiting and only occasionally it is severe enough to warrant hospitalization. SEA is the most common cause of staphylococcal food poisoning worldwide, but the involvement of other classical SEs has been also demonstrated. Of the new SE/SEls, only SEH have clearly been associated with food poisoning. However, genes encoding novel SEs as well as SEls with untested emetic activity are widely represented in S. aureus, and their role in pathogenesis may be underestimated.
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Affiliation(s)
- María Ángeles Argudín
- Department of Functional Biology (Section of Microbiology) and University Institute of Biotechnology of Asturias (IUBA), University of Oviedo, Oviedo, Spain.
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Foster TJ. Colonization and infection of the human host by staphylococci: adhesion, survival and immune evasion. Vet Dermatol 2010; 20:456-70. [PMID: 20178484 DOI: 10.1111/j.1365-3164.2009.00825.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The natural habitat of Staphylococcus aureus in humans is the moist squamous epithelium of the anterior nares. Several bacterial surface proteins are implicated in promoting adhesion to desquamated epithelial cells. Clumping factor B (ClfB) and iron-regulated surface determinant A both promote nasal colonization in rodent models, and in the case of ClfB, humans. One of the ligands involved in adhesion is cytokeratin 10. Reduction in nasal colonization can be achieved by active and passive immunization. S. aureus is well endowed with secreted and surface components that compromise innate immune responses, particularly the function of neutrophils. S. aureus secretes proteins that reduce migration of neutrophils from the bloodstream to the site of infection by impeding diapedesis and receptors for chemotactic molecules. Several secreted proteins interfere with complement C3 and C5 convertases, thus reducing the level of C3b opsonin and the chemotactic peptide C5a. Host proteases are recruited to the cell surface to enhance destruction of opsonic C3b and IgG. Surface components ClfA, protein A and polysaccharide capsule compromise the recognition of opsonins on the bacterial cell surface. If engulfed by neutrophils the intracellular bacterium can resist reactive oxygen intermediates, nitric oxide radicals, defensin peptides and bactericidal proteins. A prior infection by S. aureus does not induce complete protective immunity. This could be due to immunosuppression caused by expression of superantigen proteins that disrupt normal activation of T cells and B cells during antigen presentation. By studying the molecular pathogenesis of S. aureus infections markers might be found for investigating S. pseudintermedius infections of dogs.
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Affiliation(s)
- Timothy J Foster
- Microbiology Department, Moyne Institute of Preventive Medicine, Trinity College, Dublin 2, Ireland.
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Patel D, Wines BD, Langley RJ, Fraser JD. Specificity of staphylococcal superantigen-like protein 10 toward the human IgG1 Fc domain. THE JOURNAL OF IMMUNOLOGY 2010; 184:6283-92. [PMID: 20427768 DOI: 10.4049/jimmunol.0903311] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Staphylococcal superantigen-like protein 10 (SSL10) is a highly conserved member of the SSL family secreted by Staphylococcus aureus that displays structural but not functional similarity to superantigens. SSL10 bound to fibrinogen and fibronectin from plasma and in addition displayed striking specificity toward the gamma-1 subclass of human Igs. SSL10 also bound strongly to primate IgG but not to any other species tested, including rabbit, pig, guinea pig, cow, sheep, or mouse. A soluble form of the 12-kDa beta-grasp C-terminal domain of SSL10 (SSL10(95-197)) retained fibrinogen and fibronectin binding but lost the ability to bind IgG1, indicating that SSL10 bound to IgG1 primarily through its N-terminal oligonucleotide binding fold domain. SSL10 blocked the binding of IgG1 to FcgammaRs on monocytes and neutrophil phagocytosis of IgG1-opsonized bacteria. Mutagenesis of human IgG1 at key sites significantly reduced SSL10 binding including Lys(322) that is important for C1q binding, a combination of Leu(234) and Leu(235) that are important for FcgammaR binding, and a combination of Lys(274) and Asp(276) that together are unique to IgG1. These mutations suggest that the most likely site bound by SSL10 is the outer face of the Cgamma2 domain in close proximity to both the FcgammaR and C1q binding sites. SSL10 is a potential virulence factor for S. aureus targeting IgG1-mediated immunity.
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Affiliation(s)
- Deepa Patel
- School of Medical Sciences and Maurice Wilkins Centre of Excellence, University of Auckland, Auckland, New Zealand
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21
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Ekkelenkamp MB, Rooijakkers SH, Bonten MJ. Staphylococci and micrococci. Infect Dis (Lond) 2010. [DOI: 10.1016/b978-0-323-04579-7.00165-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/21/2023] Open
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22
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Ghumra A, Shi J, Mcintosh RS, Rasmussen IB, Braathen R, Johansen FE, Sandlie I, Mongini PK, Areschoug T, Lindahl G, Lewis MJ, Woof JM, Pleass RJ. Structural requirements for the interaction of human IgM and IgA with the human Fcalpha/mu receptor. Eur J Immunol 2009; 39:1147-56. [PMID: 19266484 PMCID: PMC3118421 DOI: 10.1002/eji.200839184] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Here we unravel the structural features of human IgM and IgA that govern their interaction with the human Fcalpha/mu receptor (hFcalpha/muR). Ligand polymerization status was crucial for the interaction, because hFcalpha/muR binding did not occur with monomeric Ab of either class. hFcalpha/muR bound IgM with an affinity in the nanomolar range, whereas the affinity for dimeric IgA (dIgA) was tenfold lower. Panels of mutant IgM and dIgA were used to identify regions critical for hFcalpha/muR binding. IgM binding required contributions from both Cmu3 and Cmu4 Fc domains, whereas for dIgA, an exposed loop in the Calpha3 domain was crucial. This loop, comprising residues Pro440-Phe443, lies at the Fc domain interface and has been implicated in the binding of host receptors FcalphaRI and polymeric Ig receptor (pIgR), as well as IgA-binding proteins produced by certain pathogenic bacteria. Substitutions within the Pro440-Phe443 loop resulted in loss of hFcalpha/muR binding. Furthermore, secretory component (SC, the extracellular portion of pIgR) and bacterial IgA-binding proteins were shown to inhibit the dIgA-hFcalpha/muR interaction. Therefore, we have identified a motif in the IgA-Fc inter-domain region critical for hFcalpha/muR interaction, and highlighted the multi-functional nature of a key site for protein-protein interaction at the IgA Fc domain interface.
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Affiliation(s)
- Ashfaq Ghumra
- Institute of Genetics, Queens Medical Centre, University of Nottingham, Nottingham, UK
| | - Jianguo Shi
- Institute of Genetics, Queens Medical Centre, University of Nottingham, Nottingham, UK
| | - Richard S. Mcintosh
- Institute of Genetics, Queens Medical Centre, University of Nottingham, Nottingham, UK
| | | | - Ranveig Braathen
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
- Institute of Pathology and Centre for Immune Regulation, University of Oslo, Rikshospitalet, Oslo, Norway
| | - Finn-Eirik Johansen
- Institute of Pathology and Centre for Immune Regulation, University of Oslo, Rikshospitalet, Oslo, Norway
| | - Inger Sandlie
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | - Patricia K. Mongini
- Department of Rheumatology, Hospital for Joint Diseases, New York University Medical Center, NY, USA
| | - Thomas Areschoug
- Department of Laboratory Medicine, Lund University, Sölvegatan, Lund, Sweden
| | - Gunnar Lindahl
- Department of Laboratory Medicine, Lund University, Sölvegatan, Lund, Sweden
| | - Melanie J. Lewis
- Division of Pathology and Neurosciences, University of Dundee Medical School, Ninewells Hospital, Dundee, UK
| | - Jenny M. Woof
- Division of Pathology and Neurosciences, University of Dundee Medical School, Ninewells Hospital, Dundee, UK
| | - Richard J. Pleass
- Institute of Genetics, Queens Medical Centre, University of Nottingham, Nottingham, UK
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Kazeeva TN, Shevelev AB. IgA-specific proteins of pathogenic bacteria. BIOCHEMISTRY (MOSCOW) 2009; 74:12-21. [DOI: 10.1134/s0006297909010027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Veldkamp KE, Strijp JAG. Innate Immune Evasion by Staphylococci. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 666:19-31. [DOI: 10.1007/978-1-4419-1601-3_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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25
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Shuiep ES, Kanbar T, Eissa N, Alber J, Lämmler C, Zschöck M, El Zubeir IEM, Weiss R. Phenotypic and genotypic characterization of Staphylococcus aureus isolated from raw camel milk samples. Res Vet Sci 2008; 86:211-5. [PMID: 18778841 DOI: 10.1016/j.rvsc.2008.07.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 07/21/2008] [Accepted: 07/23/2008] [Indexed: 11/27/2022]
Abstract
In the present study 320 milk samples collected from 160 apparently healthy camels of three different locations in Sudan were investigated for the presence of Staphylococcus aureus resulting in the isolation of this bacterial pathogen from 28 milk samples from 24 camels. Twenty-five S. aureus were identified phenotypically and by PCR mediated amplification of species-specific genes or gene segments. Investigation of the S. aureus for toxinogenic potential revealed that three S. aureus strains were positive for the enterotoxin encoding gene sec and the genes seg, sei, sem, sen and seo, representing the egc gene cluster. In addition all 25 S. aureus were positive for the superantigen-like encoding gene ssl7 (set1). Partial sequencing of gene sec of the three S. aureus strains yielded an almost complete sequence identity to the sequence of the sec variant sec2. However, all three sec2 genes of the present study showed a deletion of one base causing a frame shift and a corresponding earlier stop codon. According to the present results, the raw camel milk collected from three locations in Sudan seems to be, at least at this stage, of minor importance as vector causing staphylococcal food poisoning.
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Affiliation(s)
- E S Shuiep
- Department of Animal Production, Faculty of Veterinary Science, University of Nyala, Southern Darfur, Nyala, Sudan
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26
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Lewis MJ, Meehan M, Owen P, Woof JM. A common theme in interaction of bacterial immunoglobulin-binding proteins with immunoglobulins illustrated in the equine system. J Biol Chem 2008; 283:17615-23. [PMID: 18411272 PMCID: PMC2427354 DOI: 10.1074/jbc.m709844200] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The M protein of Streptococcus equi subsp. equi known as fibrinogen-binding protein (FgBP) is a cell wall-associated protein with antiphagocytic activity that binds IgG. Recombinant versions of the seven equine IgG subclasses were used to investigate the subclass specificity of FgBP. FgBP bound predominantly to equine IgG4 and IgG7, with little or no binding to the other subclasses. Competitive binding experiments revealed that FgBP could inhibit the binding of staphylococcal protein A and streptococcal protein G to both IgG4 and IgG7, implicating the Fc interdomain region in binding to FgBP. To identify which of the two IgG Fc domains contributed to the interaction with FgBP, we tested two human IgG1/IgA1 domain swap mutants and found that both domains are required for full binding, with the CH3 domain playing a critical role. The binding site for FgBP was further localized using recombinant equine IgG7 antibodies with single or double point mutations to residues lying at the CH2-CH3 interface. We found that interaction of FgBP with equine IgG4 and IgG7 was able to disrupt C1q binding and antibody-mediated activation of the classical complement pathway, demonstrating an effective means by which S. equi may evade the immune response. The mode of interaction of FgBP with IgG fits a common theme for bacterial Ig-binding proteins. Remarkably, for those interactions studied in detail, it emerges that all the Ig-binding proteins target the CH2-CH3 domain interface, regardless of specificity for IgG or IgA, streptococcal or staphylococcal origin, or host species (equine or human).
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Affiliation(s)
- Melanie J Lewis
- Division of Pathology and Neuroscience, University of Dundee Medical School, Ninewells Hospital, Dundee DD19SY, United Kingdom
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27
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Haas PJ, van Strijp J. Anaphylatoxins: their role in bacterial infection and inflammation. Immunol Res 2007; 37:161-75. [PMID: 17873401 DOI: 10.1007/bf02697367] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 12/16/2022]
Abstract
Activation of the complement system plays a crucial role in the pathogenesis of infection and inflammation. Especially the complement activation products C3a and C5a, known as the anaphylatoxins, are potent proinflammatory mediators. In addition to their evident role in innate immunity, it is clear that the anaphylatoxins also play a role in regulation of adaptive immune responses. The anaphylatoxins play a role in a variety of infectious and inflammatory diseases like sepsis, ischemia-reperfusion injury, immune complex diseases, and hypersensitivity diseases like asthma. In this review we discuss the role of anaphylatoxins in infection and inflammation. Furthermore, we focus on bacterial complement evasion strategies that can provide tools for further research on pathogenesis of infectious diseases and a better understanding of the role of complement and anaphylatoxins in infection and inflammation.
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Affiliation(s)
- Pieter-Jan Haas
- Eijkman-Winkler Center for Experimental Microbiology, University Medical Center Utrecht, HP:G04-614, Utrecht, 3584 CX, The Netherlands.
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28
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Chung MC, Wines BD, Baker H, Langley RJ, Baker EN, Fraser JD. The crystal structure of staphylococcal superantigen-like protein 11 in complex with sialyl Lewis X reveals the mechanism for cell binding and immune inhibition. Mol Microbiol 2007; 66:1342-55. [DOI: 10.1111/j.1365-2958.2007.05989.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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29
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Baker HM, Basu I, Chung MC, Caradoc-Davies T, Fraser JD, Baker EN. Crystal structures of the staphylococcal toxin SSL5 in complex with sialyl Lewis X reveal a conserved binding site that shares common features with viral and bacterial sialic acid binding proteins. J Mol Biol 2007; 374:1298-308. [PMID: 17996251 DOI: 10.1016/j.jmb.2007.09.091] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 09/28/2007] [Accepted: 09/28/2007] [Indexed: 12/24/2022]
Abstract
Staphylococcus aureus is a significant human pathogen. Among its large repertoire of secreted toxins is a group of staphylococcal superantigen-like proteins (SSLs). These are homologous to superantigens but do not have the same activity. SSL5 is shown here to bind to human granulocytes and to the cell surface receptors for human IgA (Fc alphaRI) and P-selectin [P-selectin glycoprotein ligand-1 (PSGL-1)] in a sialic acid (Sia)-dependent manner. Co-crystallization of SSL5 with the tetrasaccharide sialyl Lewis X (sLe(X)), a key determinant of PSGL-1 binding to P-selectin, led to crystal structures of the SSL5-sLe(X) complex at resolutions of 1.65 and 2.75 A for crystals at two pH values. In both structures, sLe(X) bound to a specific site on the surface of the C-terminal domain of SSL5 in a conformation identical with that bound by P-selectin. Conservation of the key carbohydrate binding residues indicates that this ability to bind human glycans is shared by a substantial subgroup of the SSLs, including SSL2, SSL3, SSL4, SSL5, SSL6, and SSL11. This indicates that the ability to target human glycans is an important property of this group of toxins. Structural comparisons also showed that the Sia binding site in SSL5 contains a substructure that is shared by other Sia binding proteins from bacteria as well as viruses and represents a common binding motif.
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Affiliation(s)
- Heather M Baker
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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30
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Ramsland PA, Willoughby N, Trist HM, Farrugia W, Hogarth PM, Fraser JD, Wines BD. Structural basis for evasion of IgA immunity by Staphylococcus aureus revealed in the complex of SSL7 with Fc of human IgA1. Proc Natl Acad Sci U S A 2007; 104:15051-6. [PMID: 17848512 PMCID: PMC1986611 DOI: 10.1073/pnas.0706028104] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Indexed: 11/18/2022] Open
Abstract
Infection by Staphylococcus aureus can result in severe conditions such as septicemia, toxic shock, pneumonia, and endocarditis with antibiotic resistance and persistent nasal carriage in normal individuals being key drivers of the medical impact of this virulent pathogen. In both virulent infection and nasal colonization, S. aureus encounters the host immune system and produces a wide array of factors that frustrate host immunity. One in particular, the prototypical staphylococcal superantigen-like protein SSL7, potently binds IgA and C5, thereby inhibiting immune responses dependent on these major immune mediators. We report here the three-dimensional structure of the complex of SSL7 with Fc of human IgA1 at 3.2 A resolution. Two SSL7 molecules interact with the Fc (one per heavy chain) primarily at the junction between the Calpha2 and Calpha3 domains. The binding site on each IgA chain is extensive, with SSL7 shielding most of the lateral surface of the Calpha3 domain. However, the SSL7 molecules are positioned such that they should allow binding to secretory IgA. The key IgA residues interacting with SSL7 are also bound by the leukocyte IgA receptor, FcalphaRI (CD89), thereby explaining how SSL7 potently inhibits IgA-dependent cellular effector functions mediated by FcalphaRI, such as phagocytosis, degranulation, and respiratory burst. Thus, the ability of S. aureus to subvert IgA-mediated immunity is likely to facilitate survival in mucosal environments such as the nasal passage and may contribute to systemic infections.
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MESH Headings
- Antigens, CD/chemistry
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Bacterial Proteins/chemistry
- Bacterial Proteins/immunology
- Bacterial Proteins/metabolism
- Binding Sites, Antibody
- Cells, Cultured
- Crystallography, X-Ray
- Genes, Bacterial/immunology
- Humans
- Immunoglobulin A/chemistry
- Immunoglobulin A/immunology
- Immunoglobulin A/metabolism
- Models, Molecular
- Mutagenesis
- Protein Conformation
- Receptors, Fc/chemistry
- Receptors, Fc/immunology
- Receptors, Fc/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Staphylococcus aureus/immunology
- Superantigens/chemistry
- Superantigens/immunology
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Affiliation(s)
- Paul A. Ramsland
- *The Inflammatory Disease and Structural Immunology Laboratories, The Burnet Institute, Austin Hospital, Studley Road, Heidelberg, Victoria 3084, Australia
- Department of Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia; and
- Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia
| | - Natasha Willoughby
- The Maurice Wilkins Centre and School of Medical Sciences, University of Auckland, Auckland 1020, New Zealand
| | - Halina M. Trist
- *The Inflammatory Disease and Structural Immunology Laboratories, The Burnet Institute, Austin Hospital, Studley Road, Heidelberg, Victoria 3084, Australia
| | - William Farrugia
- *The Inflammatory Disease and Structural Immunology Laboratories, The Burnet Institute, Austin Hospital, Studley Road, Heidelberg, Victoria 3084, Australia
| | - P. Mark Hogarth
- *The Inflammatory Disease and Structural Immunology Laboratories, The Burnet Institute, Austin Hospital, Studley Road, Heidelberg, Victoria 3084, Australia
- Department of Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia; and
- Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia
| | - John D. Fraser
- The Maurice Wilkins Centre and School of Medical Sciences, University of Auckland, Auckland 1020, New Zealand
| | - Bruce D. Wines
- *The Inflammatory Disease and Structural Immunology Laboratories, The Burnet Institute, Austin Hospital, Studley Road, Heidelberg, Victoria 3084, Australia
- Department of Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia; and
- Department of Immunology, Monash University, Melbourne, Victoria 3004, Australia
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Abi-Rached L, Dorighi K, Norman PJ, Yawata M, Parham P. Episodes of Natural Selection Shaped the Interactions of IgA-Fc with FcαRI and Bacterial Decoy Proteins. THE JOURNAL OF IMMUNOLOGY 2007; 178:7943-54. [PMID: 17548632 DOI: 10.4049/jimmunol.178.12.7943] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
FcalphaRI, a receptor for IgA-Fc, recruits myeloid cells to attack IgA-coated pathogens. By competing with FcalphaRI for IgA, bacterial decoys, like SSL7 of Staphylococcus aureus, subvert this defense. We examined how pathogen selection has driven the diversification and coevolution of IgA and FcalphaRI. In higher primates, the IgA binding site of FcalphaRI diversified under positive selection, a strong episode occurring in hominoid ancestors about the time of the IgA gene duplication. The differential binding of SSL7 to IgA-Fc of different species correlates with substitution at seven positions in IgA-Fc, two of which were positively selected in higher primates. Two others, which reduce SSL7 binding, emerged during episodes of positive selection in the rabbit and rodent lineages. The FcalphaRI-IgA interaction evolves episodically under two types of positive selection: pressure from pathogen decoys selects for IgA escape variants which, in turn, selects for FcalphaRI variants to keep up with the novel IgA. When FcalphaRI cannot keep up, its function is lost and the gene becomes susceptible to elimination, as occurred in the mouse genome, either by chance or selection on one of the many linked, variable immune system genes. A cluster of positively selected residues presents a putative binding site for unknown IgA-binding factors.
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Affiliation(s)
- Laurent Abi-Rached
- Department of Structural Biology and Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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32
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Rich RL, Myszka DG. Survey of the year 2006 commercial optical biosensor literature. J Mol Recognit 2007; 20:300-66. [DOI: 10.1002/jmr.862] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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33
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Bestebroer J, Poppelier MJJG, Ulfman LH, Lenting PJ, Denis CV, van Kessel KPM, van Strijp JAG, de Haas CJC. Staphylococcal superantigen-like 5 binds PSGL-1 and inhibits P-selectin–mediated neutrophil rolling. Blood 2006; 109:2936-43. [PMID: 17132726 DOI: 10.1182/blood-2006-06-015461] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
AbstractStaphylococcus aureus secretes several virulence factors interfering with host-cell functions. Staphylococcal superantigen-like (SSL) proteins are a family of 11 exotoxins with structural homology to superantigens but with generally unknown functions. Recently, we described that chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS31-121), a potent inhibitor of C5a-induced responses, is structurally homologous to the C-terminal domain of SSL5. Here, we identify P-selectin glycoprotein ligand-1 (PSGL-1), involved in the initial rolling of neutrophils along the endothelium, as a target for SSL5. SSL5 specifically bound to Chinese hamster ovary cells stably expressing PSGL-1 (CHO–PSGL-1), which was dependent of sulfation and sialylation. Furthermore, SSL5 bound to PSGL-1/Ig fusion protein immobilized on a biosensor chip. SSL5 affected binding of soluble P-selectin/Fc chimera, the principle ligand of PSGL-1, to CHO–PSGL-1 cells and inhibited adhesion of neutrophils to immobilized P-selectin under static conditions. Under flow conditions SSL5 strongly decreased neutrophil rolling on immobilized P-selectin/Fc and activated human endothelial cells. In conclusion, SSL5 interferes with the interaction between PSGL-1 and P-selectin, suggesting that S aureus uses SSL5 to prevent neutrophil extravasation toward the site of infection. This makes SSL5 a potential lead for the development of new anti-inflammatory compounds for disorders characterized by excessive recruitment of leukocytes.
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Affiliation(s)
- Jovanka Bestebroer
- Experimental Microbiology, University Medical Center Utrecht, The Netherlands.
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34
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Senior BW, Woof JM. Sites in the CH3 Domain of Human IgA1 That Influence Sensitivity to Bacterial IgA1 Proteases. THE JOURNAL OF IMMUNOLOGY 2006; 177:3913-9. [PMID: 16951354 DOI: 10.4049/jimmunol.177.6.3913] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The influence of regions, other than the hinge, on the susceptibility of human IgA1 to cleavage by diverse bacterial IgA1 proteases, was examined using IgA1 mutants bearing amino acid deletions, substitutions, and domain swaps. IgA1 lacking the tailpiece retained its susceptibility to cleavage by all of the IgA1 proteases. The domain swap molecule alpha1alpha2gamma3, in which the CH3 domain of IgA1 was exchanged for that of human IgG1, was resistant to cleavage with the type 1 and 2 serine IgA1 proteases of Neisseria meningitidis, Neisseria gonorrhoeae, and Haemophilus influenzae, but remained sensitive to cleavage with the metallo-IgA1 proteases of Streptococcus pneumoniae, Streptococcus oralis, Streptococcus sanguis, and Streptococcus mitis. Substitution of the IgA1 Calpha3 domain motif Pro440 -Phe443 into the corresponding position in the Cgamma3 domain of alpha1alpha2gamma3 resulted now in sensitivity to the type 2 IgA1 protease of N. meningitidis, indicating the possible requirement of these amino acids for sensitivity to this protease. For the H. influenzae type 2 protease, resistance of an IgA1 mutant in which the CH3 domain residues 399-409 were exchanged with those from IgG1, but sensitivity of mutant HuBovalpha3 in which the Calpha3 domain of bovine IgA replaces that of human IgA1, suggests that CH3 domain residues Glu403, Gln406, and Thr409 influence sensitivity to this enzyme. Hence, unlike the situation with the metallo-IgA1 proteases of Streptococcus spp., the sensitivity of human IgA1 to cleavage with the serine IgA1 proteases of Neisseria and Haemophilus involves their binding to different sites specifically in the CH3 domain.
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Affiliation(s)
- Bernard W Senior
- Division of Pathology and Neuroscience, University of Dundee Medical School, Ninewells Hospital, Dundee, United Kingdom
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Abstract
The varied interaction of the Fc region of IgA with receptors confers this antibody class with many of its unique properties. The epithelial polymeric Ig receptor on mucosal epithelial cells transports polymeric immunoglobulin A (pIgA) produced by mucosal B cells to the mucosal surface where, in complex with the secretory component (SC), this secretory immunoglobulin A (SIgA) excludes the multitude of dietary, environmental, and microbial antigens that continuously bombard the mucosae. In health, this IgA-mediated exclusion not only forms the initial defence against infection, it also spares the systemic immune system from potentially deleterious responses to innocuous antigens which can otherwise culminate in inflammatory bowel disease or asthma. Beyond antigen exclusion, in closer encounters with antigens, IgA receptors play roles in protective immunity and disease. FcaRI is the principal myeloid IgA receptor and is responsible for differing IgA-mediated effector responses such as respiratory burst, degranulation, and phagocytosis variously by granulyoctes, monocytes, and macrophages. Furthermore an unknown IgA receptor specific for the secretory component (SC) elicits powerful effector responses from eosinophils. On dendritic cells, FcaRI participates in antigen presentation while on microfold cells, key cells in mucosal antigen presentation, another unknown IgA receptor functions in the transport of antigens across the mucosal epithelial barrier. The activity of another uncharacterized IgA1/IgD receptor on T cells may affect autoimmune disorders. The interplay of different IgA receptors affects immune complex deposition in the common renal disease immunoglobulin A nephropathy (IgAN). Finally, the therapeutic application of various IgA receptors has been sought in the areas of infectious disease, vaccines, and cancer.
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Affiliation(s)
- Bruce D Wines
- Helen Macpherson Smith Trust Inflammatory Disease Laboratory, The Macfarlane Burnet Institute for Medical Research and Public Health, Austin Health Campus, Heidelberg, Victoria, Australia.
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