1
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Wang P, Fredj Z, Zhang H, Rong G, Bian S, Sawan M. Blocking Superantigen-Mediated Diseases: Challenges and Future Trends. J Immunol Res 2024; 2024:2313062. [PMID: 38268531 PMCID: PMC10807946 DOI: 10.1155/2024/2313062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/15/2023] [Accepted: 12/30/2023] [Indexed: 01/26/2024] Open
Abstract
Superantigens are virulence factors secreted by microorganisms that can cause various immune diseases, such as overactivating the immune system, resulting in cytokine storms, rheumatoid arthritis, and multiple sclerosis. Some studies have demonstrated that superantigens do not require intracellular processing and instated bind as intact proteins to the antigen-binding groove of major histocompatibility complex II on antigen-presenting cells, resulting in the activation of T cells with different T-cell receptor Vβ and subsequent overstimulation. To combat superantigen-mediated diseases, researchers have employed different approaches, such as antibodies and simulated peptides. However, due to the complex nature of superantigens, these approaches have not been entirely successful in achieving optimal therapeutic outcomes. CD28 interacts with members of the B7 molecule family to activate T cells. Its mimicking peptide has been suggested as a potential candidate to block superantigens, but it can lead to reduced T-cell activity while increasing the host's infection risk. Thus, this review focuses on the use of drug delivery methods to accurately target and block superantigens, while reducing the adverse effects associated with CD28 mimic peptides. We believe that this method has the potential to provide an effective and safe therapeutic strategy for superantigen-mediated diseases.
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Affiliation(s)
- Pengbo Wang
- CenBRAIN Neurotech, School of Engineering, Westlake University, Hangzhou 310030, China
| | - Zina Fredj
- CenBRAIN Neurotech, School of Engineering, Westlake University, Hangzhou 310030, China
| | - Hongyong Zhang
- CenBRAIN Neurotech, School of Engineering, Westlake University, Hangzhou 310030, China
| | - Guoguang Rong
- CenBRAIN Neurotech, School of Engineering, Westlake University, Hangzhou 310030, China
| | - Sumin Bian
- CenBRAIN Neurotech, School of Engineering, Westlake University, Hangzhou 310030, China
| | - Mohamad Sawan
- CenBRAIN Neurotech, School of Engineering, Westlake University, Hangzhou 310030, China
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2
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Uzunҫayır S, Vera‐Rodriguez A, Regenthal P, Åbacka H, Emanuelsson C, Bahl CD, Lindkvist‐Petersson K. Analyses of the complex formation of staphylococcal enterotoxin A and the human gp130 cytokine receptor. FEBS Lett 2022; 596:910-923. [DOI: 10.1002/1873-3468.14292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/14/2021] [Accepted: 01/10/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Sibel Uzunҫayır
- Department of Experimental Medical Science Lund University BMC C13 22 184 Lund Sweden
| | - Arturo Vera‐Rodriguez
- Institute for Protein Innovation Boston USA
- Division of Hematology‐Oncology, Boston Children’s Hospital Harvard Medical School Boston USA
| | - Paulina Regenthal
- Department of Experimental Medical Science Lund University BMC C13 22 184 Lund Sweden
| | - Hannah Åbacka
- Department of Experimental Medical Science Lund University BMC C13 22 184 Lund Sweden
| | - Cecilia Emanuelsson
- Department of Chemistry Division for Biochemistry and Structural Biology Lund University Lund Sweden
| | - Christopher D. Bahl
- Institute for Protein Innovation Boston USA
- Division of Hematology‐Oncology, Boston Children’s Hospital Harvard Medical School Boston USA
| | - Karin Lindkvist‐Petersson
- Department of Experimental Medical Science Lund University BMC C13 22 184 Lund Sweden
- LINXS ‐ Lund Institute of Advanced Neutron and X‐ray Science Scheelevägen 19 SE‐223 70 Lund Sweden
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3
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Zeng C, Liu Z, Han Z. Structure of Staphylococcal Enterotoxin N: Implications for Binding Properties to Its Cellular Proteins. Int J Mol Sci 2019; 20:ijms20235921. [PMID: 31775346 PMCID: PMC6928602 DOI: 10.3390/ijms20235921] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 11/20/2019] [Accepted: 11/22/2019] [Indexed: 01/26/2023] Open
Abstract
Staphylococcus aureus strains produce a unique family of immunostimulatory exotoxins termed as bacterial superantigens (SAgs), which cross-link major histocompatibility complex class II (MHC II) molecule and T-cell receptor (TCR) to stimulate large numbers of T cells at extremely low concentrations. SAgs are associated with food poisoning and toxic shock syndrome. To date, 26 genetically distinct staphylococcal SAgs have been reported. This study reports the first X-ray structure of newly characterized staphylococcal enterotoxin N (SEN). SEN possesses the classical two domain architecture that includes an N-terminal oligonucleotide-binding fold and a C-terminal β-grasp domain. Amino acid and structure alignments revealed that several critical amino acids that are proposed to be responsible for MHC II and TCR molecule engagements are variable in SEN, suggesting that SEN may adopt a different binding mode to its cellular receptors. This work helps better understand the mechanisms of action of SAgs.
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Affiliation(s)
- Chi Zeng
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China; (C.Z.); (Z.L.)
- Hubei Province Fresh Food Engineering Research Center, Wuhan Polytechnic University, Wuhan 430023, China
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture), Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
| | - Zhaoxin Liu
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China; (C.Z.); (Z.L.)
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zhenggang Han
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China; (C.Z.); (Z.L.)
- Correspondence:
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4
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Abstract
ABSTRACT
Streptococcus pyogenes
(i.e., the group A
Streptococcus
) is a human-restricted and versatile bacterial pathogen that produces an impressive arsenal of both surface-expressed and secreted virulence factors. Although surface-expressed virulence factors are clearly vital for colonization, establishing infection, and the development of disease, the secreted virulence factors are likely the major mediators of tissue damage and toxicity seen during active infection. The collective exotoxin arsenal of
S. pyogenes
is rivaled by few bacterial pathogens and includes extracellular enzymes, membrane active proteins, and a variety of toxins that specifically target both the innate and adaptive arms of the immune system, including the superantigens; however, despite their role in
S. pyogenes
disease, each of these virulence factors has likely evolved with humans in the context of asymptomatic colonization and transmission. In this article, we focus on the biology of the true secreted exotoxins of the group A
Streptococcus
, as well as their roles in the pathogenesis of human disease.
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5
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Shaler CR, Choi J, Rudak PT, Memarnejadian A, Szabo PA, Tun-Abraham ME, Rossjohn J, Corbett AJ, McCluskey J, McCormick JK, Lantz O, Hernandez-Alejandro R, Haeryfar SM. MAIT cells launch a rapid, robust and distinct hyperinflammatory response to bacterial superantigens and quickly acquire an anergic phenotype that impedes their cognate antimicrobial function: Defining a novel mechanism of superantigen-induced immunopathology and immunosuppression. PLoS Biol 2017. [PMID: 28632753 PMCID: PMC5478099 DOI: 10.1371/journal.pbio.2001930] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Superantigens (SAgs) are potent exotoxins secreted by Staphylococcus aureus and Streptococcus pyogenes. They target a large fraction of T cell pools to set in motion a "cytokine storm" with severe and sometimes life-threatening consequences typically encountered in toxic shock syndrome (TSS). Given the rapidity with which TSS develops, designing timely and truly targeted therapies for this syndrome requires identification of key mediators of the cytokine storm's initial wave. Equally important, early host responses to SAgs can be accompanied or followed by a state of immunosuppression, which in turn jeopardizes the host's ability to combat and clear infections. Unlike in mouse models, the mechanisms underlying SAg-associated immunosuppression in humans are ill-defined. In this work, we have identified a population of innate-like T cells, called mucosa-associated invariant T (MAIT) cells, as the most powerful source of pro-inflammatory cytokines after exposure to SAgs. We have utilized primary human peripheral blood and hepatic mononuclear cells, mouse MAIT hybridoma lines, HLA-DR4-transgenic mice, MAIThighHLA-DR4+ bone marrow chimeras, and humanized NOD-scid IL-2Rγnull mice to demonstrate for the first time that: i) mouse and human MAIT cells are hyperresponsive to SAgs, typified by staphylococcal enterotoxin B (SEB); ii) the human MAIT cell response to SEB is rapid and far greater in magnitude than that launched by unfractionated conventional T, invariant natural killer T (iNKT) or γδ T cells, and is characterized by production of interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-2, but not IL-17A; iii) high-affinity MHC class II interaction with SAgs, but not MHC-related protein 1 (MR1) participation, is required for MAIT cell activation; iv) MAIT cell responses to SEB can occur in a T cell receptor (TCR) Vβ-specific manner but are largely contributed by IL-12 and IL-18; v) as MAIT cells are primed by SAgs, they also begin to develop a molecular signature consistent with exhaustion and failure to participate in antimicrobial defense. Accordingly, they upregulate lymphocyte-activation gene 3 (LAG-3), T cell immunoglobulin and mucin-3 (TIM-3), and/or programmed cell death-1 (PD-1), and acquire an anergic phenotype that interferes with their cognate function against Klebsiella pneumoniae and Escherichia coli; vi) MAIT cell hyperactivation and anergy co-utilize a signaling pathway that is governed by p38 and MEK1/2. Collectively, our findings demonstrate a pathogenic, rather than protective, role for MAIT cells during infection. Furthermore, we propose a novel mechanism of SAg-associated immunosuppression in humans. MAIT cells may therefore provide an attractive therapeutic target for the management of both early and late phases of severe SAg-mediated illnesses.
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MESH Headings
- Animals
- Antigens, Bacterial/metabolism
- Antigens, Bacterial/toxicity
- Bone Marrow Cells/cytology
- Bone Marrow Cells/drug effects
- Bone Marrow Cells/immunology
- Bone Marrow Cells/metabolism
- Cell Line
- Cells, Cultured
- Clonal Anergy/drug effects
- Crosses, Genetic
- Enterotoxins/metabolism
- Enterotoxins/toxicity
- Female
- Humans
- Hybridomas
- Immunity, Innate
- Leukocytes, Mononuclear/cytology
- Leukocytes, Mononuclear/drug effects
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Lymphocyte Activation/drug effects
- Mice
- Mice, Inbred NOD
- Mice, Knockout
- Mice, SCID
- Mice, Transgenic
- Models, Immunological
- Mucosal-Associated Invariant T Cells/cytology
- Mucosal-Associated Invariant T Cells/drug effects
- Mucosal-Associated Invariant T Cells/immunology
- Mucosal-Associated Invariant T Cells/metabolism
- Specific Pathogen-Free Organisms
- Staphylococcus aureus/immunology
- Staphylococcus aureus/metabolism
- Streptococcus pyogenes/immunology
- Streptococcus pyogenes/metabolism
- Superantigens/metabolism
- Superantigens/toxicity
- Transplantation Chimera/blood
- Transplantation Chimera/immunology
- Transplantation Chimera/metabolism
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Affiliation(s)
- Christopher R. Shaler
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Joshua Choi
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Patrick T. Rudak
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Arash Memarnejadian
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Peter A. Szabo
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Mauro E. Tun-Abraham
- Division of General Surgery, Department of Surgery, Western University, London, Ontario, Canada
| | - Jamie Rossjohn
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Institute of Infection and Immunity, Cardiff University School of Medicine, Cardiff, United Kingdom
| | - Alexandra J. Corbett
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | - James McCluskey
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | - John K. McCormick
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Centre for Human Immunology, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - Olivier Lantz
- Laboratoire d'Immunologie and INSERM U932, Institut Curie, Paris, France
| | - Roberto Hernandez-Alejandro
- Division of General Surgery, Department of Surgery, Western University, London, Ontario, Canada
- Division of Transplantation, Department of Surgery, University of Rochester Medical Center, Rochester, New York, United States of America
| | - S.M. Mansour Haeryfar
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Centre for Human Immunology, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- Division of Clinical Immunology and Allergy, Department of Medicine, Western University, London, Ontario, Canada
- * E-mail:
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6
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Benkerroum N. Staphylococcal enterotoxins and enterotoxin-like toxins with special reference to dairy products: An overview. Crit Rev Food Sci Nutr 2017; 58:1943-1970. [DOI: 10.1080/10408398.2017.1289149] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Noreddine Benkerroum
- Department of Food Science and Agricultural Chemistry, Macdonald-Stewart Building, McGill University, Macdonald Campus, Sainte-Anne-de-Bellevue, Canada
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7
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Regenthal P, Hansen JS, André I, Lindkvist-Petersson K. Thermal stability and structural changes in bacterial toxins responsible for food poisoning. PLoS One 2017; 12:e0172445. [PMID: 28207867 PMCID: PMC5313198 DOI: 10.1371/journal.pone.0172445] [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: 12/21/2016] [Accepted: 02/03/2017] [Indexed: 11/17/2022] Open
Abstract
The staphylococcal enterotoxins (SEs) are secreted by the bacteria Staphylococcus aureus and are the most common causative agent in staphylococcal food poisoning. The staphylococcal enterotoxin A (SEA) has been associated with large staphylococcal food poisoning outbreaks, but newer identified SEs, like staphylococcal enterotoxin H (SEH) has recently been shown to be present at similar levels as SEA in food poisoning outbreaks. Thus, we set out to investigate the thermo-stability of the three-dimensional structures of SEA, SEH and staphylococcal enterotoxin E (SEE), since heat inactivation is a common method to inactivate toxins during food processing. Interestingly, the investigated toxins behaved distinctly different upon heating. SEA and SEE were more stable at slightly acidic pH values, while SEH adopted an extremely stable structure at neutral pH, with almost no effects on secondary structural elements upon heating to 95°C, and with reversible formation of tertiary structure upon subsequent cooling to room temperature. Taken together, the data suggests that the family of staphylococcal enterotoxins have different ability to withstand heat, and thus the exact profile of heat inactivation for all SEs causing food poisoning needs to be considered to improve food safety.
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Affiliation(s)
- Paulina Regenthal
- Department of Experimental Medical Science, Lund University, BMC, Lund, Sweden
| | - Jesper S Hansen
- Department of Experimental Medical Science, Lund University, BMC, Lund, Sweden
| | - Ingemar André
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
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8
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Rödström KEJ, Regenthal P, Lindkvist-Petersson K. Structure of Staphylococcal Enterotoxin E in Complex with TCR Defines the Role of TCR Loop Positioning in Superantigen Recognition. PLoS One 2015; 10:e0131988. [PMID: 26147596 PMCID: PMC4492778 DOI: 10.1371/journal.pone.0131988] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 06/09/2015] [Indexed: 11/18/2022] Open
Abstract
T cells are crucial players in cell-mediated immunity. The specificity of their receptor, the T cell receptor (TCR), is central for the immune system to distinguish foreign from host antigens. Superantigens are bacterial toxins capable of inducing a toxic immune response by cross-linking the TCR and the major histocompatibility complex (MHC) class II and circumventing the antigen specificity. Here, we present the structure of staphylococcal enterotoxin E (SEE) in complex with a human T cell receptor, as well as the unligated T cell receptor structure. There are clear structural changes in the TCR loops upon superantigen binding. In particular, the HV4 loop moves to circumvent steric clashes upon complex formation. In addition, a predicted ternary model of SEE in complex with both TCR and MHC class II displays intermolecular contacts between the TCR α-chain and the MHC, suggesting that the TCR α-chain is of importance for complex formation.
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Affiliation(s)
- Karin E. J. Rödström
- Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden
| | - Paulina Regenthal
- Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden
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9
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Dang AK, Jain RW, Craig HC, Kerfoot SM. B cell recognition of myelin oligodendrocyte glycoprotein autoantigen depends on immunization with protein rather than short peptide, while B cell invasion of the CNS in autoimmunity does not. J Neuroimmunol 2015; 278:73-84. [DOI: 10.1016/j.jneuroim.2014.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/12/2014] [Accepted: 12/08/2014] [Indexed: 10/24/2022]
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10
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Rödström KEJ, Elbing K, Lindkvist-Petersson K. Structure of the superantigen staphylococcal enterotoxin B in complex with TCR and peptide-MHC demonstrates absence of TCR-peptide contacts. THE JOURNAL OF IMMUNOLOGY 2014; 193:1998-2004. [PMID: 25015819 DOI: 10.4049/jimmunol.1401268] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Superantigens are immune-stimulatory toxins produced by Staphylococcus aureus, which are able to interact with host immune receptors to induce a massive release of cytokines, causing toxic shock syndrome and possibly death. In this article, we present the x-ray structure of staphylococcal enterotoxin B (SEB) in complex with its receptors, the TCR and MHC class II, forming a ternary complex. The structure, in combination with functional analyses, clearly shows how SEB adopts a wedge-like position when binding to the β-chain of TCR, allowing for an interaction between the α-chain of TCR and MHC. Furthermore, the binding mode also circumvents contact between TCR and the peptide presented by MHC, which enables SEB to initiate a peptide-independent activation of T cells.
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Affiliation(s)
- Karin E J Rödström
- Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Karin Elbing
- Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
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11
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Superantigens subvert the neutrophil response to promote abscess formation and enhance Staphylococcus aureus survival in vivo. Infect Immun 2014; 82:3588-98. [PMID: 24914221 DOI: 10.1128/iai.02110-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Staphylococcus aureus is a versatile bacterial pathogen that produces T cell-activating toxins known as superantigens (SAgs). Although excessive immune activation by SAgs can induce a dysregulated cytokine storm as a component of what is known as toxic shock syndrome (TSS), the contribution of SAgs to the staphylococcal infection process is not well defined. Here, we evaluated the role of the bacterial superantigen staphylococcal enterotoxin A (SEA) in a bacteremia model using humanized transgenic mice expressing SAg-responsive HLA-DR4 molecules. Infection with S. aureus Newman induced SEA-dependent Vβ skewing of T cells and enhanced bacterial survival in the liver compared with infection by sea knockout strain. SEA-induced gamma interferon, interleukin-12, and chemokine responses resulted in increased infiltration of CD11b(+) Ly6G(+) neutrophils into the liver, promoting the formation of abscesses that contained large numbers of viable staphylococci. Hepatic abscesses occurred significantly more frequently in S. aureus Newman-infected livers than in livers infected with the Newman sea knockout strain, promoting the survival of S. aureus in vivo. This represents a novel mechanism during infection whereby S. aureus utilizes SAgs to form a specialized niche and manipulate the immune system.
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12
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Kasper KJ, Zeppa JJ, Wakabayashi AT, Xu SX, Mazzuca DM, Welch I, Baroja ML, Kotb M, Cairns E, Cleary PP, Haeryfar SMM, McCormick JK. Bacterial superantigens promote acute nasopharyngeal infection by Streptococcus pyogenes in a human MHC Class II-dependent manner. PLoS Pathog 2014; 10:e1004155. [PMID: 24875883 PMCID: PMC4038607 DOI: 10.1371/journal.ppat.1004155] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/17/2014] [Indexed: 11/19/2022] Open
Abstract
Establishing the genetic determinants of niche adaptation by microbial pathogens to specific hosts is important for the management and control of infectious disease. Streptococcus pyogenes is a globally prominent human-specific bacterial pathogen that secretes superantigens (SAgs) as 'trademark' virulence factors. SAgs function to force the activation of T lymphocytes through direct binding to lateral surfaces of T cell receptors and class II major histocompatibility complex (MHC-II) molecules. S. pyogenes invariably encodes multiple SAgs, often within putative mobile genetic elements, and although SAgs are documented virulence factors for diseases such as scarlet fever and the streptococcal toxic shock syndrome (STSS), how these exotoxins contribute to the fitness and evolution of S. pyogenes is unknown. Here we show that acute infection in the nasopharynx is dependent upon both bacterial SAgs and host MHC-II molecules. S. pyogenes was rapidly cleared from the nasal cavity of wild-type C57BL/6 (B6) mice, whereas infection was enhanced up to ∼10,000-fold in B6 mice that express human MHC-II. This phenotype required the SpeA superantigen, and vaccination with an MHC -II binding mutant toxoid of SpeA dramatically inhibited infection. Our findings indicate that streptococcal SAgs are critical for the establishment of nasopharyngeal infection, thus providing an explanation as to why S. pyogenes produces these potent toxins. This work also highlights that SAg redundancy exists to avoid host anti-SAg humoral immune responses and to potentially overcome host MHC-II polymorphisms.
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Affiliation(s)
- Katherine J. Kasper
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Joseph J. Zeppa
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Adrienne T. Wakabayashi
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Stacey X. Xu
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Delfina M. Mazzuca
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Ian Welch
- Department of Animal Care and Veterinary Services, Western University, London, Ontario, Canada
| | - Miren L. Baroja
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - Malak Kotb
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Ewa Cairns
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - P. Patrick Cleary
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - S. M. Mansour Haeryfar
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - John K. McCormick
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- * E-mail:
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13
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Patterson KG, Dixon Pittaro JL, Bastedo PS, Hess DA, Haeryfar SMM, McCormick JK. Control of established colon cancer xenografts using a novel humanized single chain antibody-streptococcal superantigen fusion protein targeting the 5T4 oncofetal antigen. PLoS One 2014; 9:e95200. [PMID: 24736661 PMCID: PMC3988171 DOI: 10.1371/journal.pone.0095200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/25/2014] [Indexed: 01/21/2023] Open
Abstract
Superantigens (SAgs) are microbial toxins that cross-link T cell receptors with major histocompatibility class II (MHC-II) molecules leading to the activation of large numbers of T cells. Herein, we describe the development and preclinical testing of a novel tumor-targeted SAg (TTS) therapeutic built using the streptococcal pyrogenic exotoxin C (SpeC) SAg and targeting cancer cells expressing the 5T4 tumor-associated antigen (TAA). To inhibit potentially harmful widespread immune cell activation, a SpeC mutation within the high-affinity MHC-II binding interface was generated (SpeCD203A) that demonstrated a pronounced reduction in mitogenic activity, yet this mutant could still induce immune cell-mediated cancer cell death in vitro. To target 5T4+ cancer cells, we engineered a humanized single chain variable fragment (scFv) antibody to recognize 5T4 (scFv5T4). Specific targeting of scFv5T4 was verified. SpeCD203A fused to scFv5T4 maintained the ability to activate and induce immune cell-mediated cytotoxicity of colorectal cancer cells. Using a xenograft model of established human colon cancer, we demonstrated that the SpeC-based TTS was able to control the growth and spread of large tumors in vivo. This required both TAA targeting by scFv5T4 and functional SAg activity. These studies lay the foundation for the development of streptococcal SAgs as ‘next-generation’ TTSs for cancer immunotherapy.
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MESH Headings
- Animals
- Antibodies, Monoclonal, Humanized/genetics
- Antibodies, Monoclonal, Humanized/immunology
- Antigens, Neoplasm/immunology
- Cell Line, Tumor
- Cell Proliferation
- Cell Transformation, Neoplastic
- Colonic Neoplasms/immunology
- Colonic Neoplasms/pathology
- Colonic Neoplasms/therapy
- Humans
- Immunotherapy/methods
- Mice
- Models, Molecular
- Protein Conformation
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/immunology
- Single-Chain Antibodies/genetics
- Single-Chain Antibodies/immunology
- Streptococcus/immunology
- Superantigens/genetics
- Superantigens/immunology
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
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Affiliation(s)
- Kelcey G. Patterson
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | | | - Peter S. Bastedo
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - David A. Hess
- Department of Physiology and Pharmacology, Western University, London Ontario, Canada
- Vascular Biology Research Group, Robarts Research Institute, London, Ontario, Canada
| | - S. M. Mansour Haeryfar
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Centre for Human Immunology, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - John K. McCormick
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Centre for Human Immunology, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- * E-mail:
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14
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Abstract
SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.
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15
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Anantha RV, Kasper KJ, Patterson KG, Zeppa JJ, Delport J, McCormick JK. Fournier's gangrene of the penis caused by Streptococcus dysgalactiae subspecies equisimilis: case report and incidence study in a tertiary-care hospital. BMC Infect Dis 2013; 13:381. [PMID: 23957431 PMCID: PMC3751815 DOI: 10.1186/1471-2334-13-381] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 08/19/2013] [Indexed: 11/12/2022] Open
Abstract
Background Fournier’s gangrene is a rare necrotizing soft tissue infection of the scrotum and penis. We report, to our knowledge, the first case of Fournier’s gangrene caused by Streptococcus dysgalactiae subsp. equisimilis (SDSE), a strain of pyogenic β-hemolytic streptococci that is increasingly being recognized as an important human pathogen. Case presentation We describe a healthy 59 year-old Caucasian male who presented to the emergency department with Fournier’s gangrene of the penis and scrotum, with extension to the anterior abdominal wall. He underwent urgent surgical debridement of his scrotum, penis, and anterior abdomen. Swabs from the scrotum grew Gram-positive cocci, which were initially identified as Streptococcus anginosus group by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). However, polymerase chain reaction (PCR) amplification and sequencing of the 16S rRNA gene identified the isolate as Streptococcus dysgalatiae subspecies equisimilis (SDSE). The incidences of invasive S. anginosus group and SDSE infections at the London Health Sciences Centre, a tertiary-care institution in southwestern Ontario, were determined between August 1, 2011 and August 31, 2012, revealing a slightly lower rate of SDSE (3.2 cases per 100,000 population) than other studies. Conclusions This case highlights a unique disease manifestation of the emerging human pathogen Streptococcus dysgalatiae subspecies equisimilis that has not been previously reported. This case also underscores the limitations of MALDI-TOF MS in differentiating between closely-related streptococcal species which may have different pathogenic profiles.
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16
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Galeotti CL, Bove E, Pezzicoli A, Nogarotto R, Norais N, Pileri S, Lelli B, Falugi F, Balloni S, Tedde V, Chiarot E, Bombaci M, Soriani M, Bracci L, Grandi G, Grifantini R. Surface interactome in Streptococcus pyogenes. Mol Cell Proteomics 2011; 11:M111.015206. [PMID: 22199230 DOI: 10.1074/mcp.m111.015206] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Very few studies have so far been dedicated to the systematic analysis of protein interactions occurring between surface and/or secreted proteins in bacteria. Such interactions are expected to play pivotal biological roles that deserve investigation. Taking advantage of the availability of a detailed map of surface and secreted proteins in Streptococcus pyogenes (group A Streptococcus (GAS)), we used protein array technology to define the "surface interactome" in this important human pathogen. Eighty-three proteins were spotted on glass slides in high density format, and each of the spotted proteins was probed for its capacity to interact with any of the immobilized proteins. A total of 146 interactions were identified, 25 of which classified as "reciprocal," namely, interactions that occur irrespective of which of the two partners was immobilized on the chip or in solution. Several of these interactions were validated by surface plasmon resonance and supported by confocal microscopy analysis of whole bacterial cells. By this approach, a number of interesting interactions have been discovered, including those occurring between OppA, DppA, PrsA, and TlpA, proteins known to be involved in protein folding and transport. These proteins, all localizing at the septum, might be part, together with HtrA, of the recently described ExPortal complex of GAS. Furthermore, SpeI was found to strongly interact with the metal transporters AdcA and Lmb. Because SpeI strictly requires zinc to exert its function, this finding provides evidence on how this superantigen, a major player in GAS pathogenesis, can acquire the metal in the host environment, where it is largely sequestered by carrier proteins. We believe that the approach proposed herein can lead to a deeper knowledge of the mechanisms underlying bacterial invasion, colonization, and pathogenesis.
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17
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Hayworth JL, Mazzuca DM, Maleki Vareki S, Welch I, McCormick JK, Haeryfar SMM. CD1d-independent activation of mouse and human iNKT cells by bacterial superantigens. Immunol Cell Biol 2011; 90:699-709. [PMID: 22041925 DOI: 10.1038/icb.2011.90] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Invariant NKT (iNKT) cells are infrequent but important immunomodulatory lymphocytes that exhibit CD1d-restricted reactivity with glycolipid Ags. iNKT cells express a unique T-cell receptor (TCR) composed of an invariant α-chain, paired with a limited range of β-chains. Superantigens (SAgs) are microbial toxins defined by their ability to activate conventional T cells in a TCR β-chain variable domain (Vβ)-specific manner. However, whether iNKT cells are directly activated by bacterial SAgs remains an open question. Herein, we explored the responsiveness of mouse and human iNKT cells to a panel of staphylococcal and streptococcal SAgs and examined the contribution of major histocompatibility complex (MHC) class II and CD1d to these responses. Bacterial SAgs that target mouse Vβ8, such as staphylococcal enterotoxin B (SEB), were able to activate mouse hybridoma and primary hepatic iNKT cells in the presence of mouse APCs expressing human leukocyte antigen (HLA)-DR4. iNKT cell-mediated cytokine secretion in SEB-challenged HLA-DR4-transgenic mice was CD1d-independent and accompanied by a high interferon-γ:interleukin-4 ratio consistent with an in vivo Th1 bias. Furthermore, iNKT cells from SEB-injected HLA-DR4-transgenic mice, and iNKT cells from SEB-treated human PBMCs, showed early activation by intracellular cytokine staining and CD69 expression. Unlike iNKT cell stimulation by α-galactosylceramide, stimulation by SEB did not induce TCR downregulation of either mouse or human iNKT cells. We conclude that Vβ8-targeting bacterial SAgs can activate iNKT cells by utilizing a novel pathway that requires MHC class II interactions, but not CD1d. Therefore, iNKT cells fulfill important effector functions in response to bacterial SAgs and may provide attractive targets in the management of SAg-induced illnesses.
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Affiliation(s)
- Jacqueline L Hayworth
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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18
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Brosnahan AJ, Schlievert PM. Gram-positive bacterial superantigen outside-in signaling causes toxic shock syndrome. FEBS J 2011; 278:4649-67. [PMID: 21535475 DOI: 10.1111/j.1742-4658.2011.08151.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Staphylococcus aureus and Streptococcus pyogenes (group A streptococci) are Gram-positive pathogens capable of producing a variety of bacterial exotoxins known as superantigens. Superantigens interact with antigen-presenting cells (APCs) and T cells to induce T cell proliferation and massive cytokine production, which leads to fever, rash, capillary leak and subsequent hypotension, the major symptoms of toxic shock syndrome. Both S. aureus and group A streptococci colonize mucosal surfaces, including the anterior nares and vagina for S. aureus, and the oropharynx and less commonly the vagina for group A streptococci. However, due to their abilities to secrete a variety of virulence factors, the organisms can also cause illnesses from the mucosa. This review provides an updated discussion of the biochemical and structural features of one group of secreted virulence factors, the staphylococcal and group A streptococcal superantigens, and their abilities to cause toxic shock syndrome from a mucosal surface. The main focus of this review, however, is the abilities of superantigens to induce cytokines and chemokines from epithelial cells, which has been linked to a dodecapeptide region that is relatively conserved among all superantigens and is distinct from the binding sites required for interactions with APCs and T cells. This phenomenon, termed outside-in signaling, acts to recruit adaptive immune cells to the submucosa, where the superantigens can then interact with those cells to initiate the final cytokine cascades that lead to toxic shock syndrome.
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Affiliation(s)
- Amanda J Brosnahan
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, USA
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19
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Fernández MM, Cho S, De Marzi MC, Kerzic MC, Robinson H, Mariuzza RA, Malchiodi EL. Crystal structure of staphylococcal enterotoxin G (SEG) in complex with a mouse T-cell receptor {beta} chain. J Biol Chem 2011; 286:1189-95. [PMID: 21059660 PMCID: PMC3020726 DOI: 10.1074/jbc.m110.142471] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 09/20/2010] [Indexed: 11/06/2022] Open
Abstract
Superantigens (SAgs) are bacterial or viral toxins that bind MHC class II (MHC-II) molecules and T-cell receptor (TCR) in a nonconventional manner, inducing T-cell activation that leads to inflammatory cytokine production, which may result in acute toxic shock. In addition, the emerging threat of purpura fulminans and community-associated meticillin-resistant Staphylococcus aureus emphasizes the importance of a better characterization of SAg binding to their natural ligands that may allow the development of reagents to neutralize their action. The three-dimensional structure of the complex between a mouse TCR β chain (mVβ8.2) and staphylococcal enterotoxin G (SEG) at 2.0 Å resolution revealed a binding site that does not conserve the "hot spots" present in mVβ8.2-SEC2, mVβ8.2-SEC3, mVβ8.2-SEB, and mVβ8.2-SPEA complexes. Analysis of the mVβ8.2-SEG interface allowed us to explain the higher affinity of this complex compared with the others, which may account for the early activation of T-cells bearing mVβ8.2 by SEG. This mode of interaction between SEG and mVβ8.2 could be an adaptive advantage to bestow on the pathogen a faster rate of colonization of the host.
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Affiliation(s)
- Marisa M. Fernández
- From the Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 4to P, 1113 Buenos Aires, Argentina
- the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Sangwoo Cho
- the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Mauricio C. De Marzi
- From the Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 4to P, 1113 Buenos Aires, Argentina
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Ruta 5 y Constitución, 6700 Luján, Buenos Aires, Argentina, and
| | - Melissa C. Kerzic
- the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Howard Robinson
- Department of Biology, Brookhaven National Laboratory, Upton, New York 11973
| | - Roy A. Mariuzza
- the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Emilio L. Malchiodi
- From the Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 4to P, 1113 Buenos Aires, Argentina
- the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
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20
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Nur-ur Rahman AKM, Bonsor DA, Herfst CA, Pollard F, Peirce M, Wyatt AW, Kasper KJ, Madrenas J, Sundberg EJ, McCormick JK. The T cell receptor beta-chain second complementarity determining region loop (CDR2beta governs T cell activation and Vbeta specificity by bacterial superantigens. J Biol Chem 2010; 286:4871-81. [PMID: 21127057 DOI: 10.1074/jbc.m110.189068] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Superantigens (SAgs) are microbial toxins defined by their ability to activate T lymphocytes in a T cell receptor (TCR) β-chain variable domain (Vβ)-specific manner. Although existing structural information indicates that diverse bacterial SAgs all uniformly engage the Vβ second complementarity determining region (CDR2β) loop, the molecular rules that dictate SAg-mediated T cell activation and Vβ specificity are not fully understood. Herein we report the crystal structure of human Vβ2.1 (hVβ2.1) in complex with the toxic shock syndrome toxin-1 (TSST-1) SAg, and mutagenesis of hVβ2.1 indicates that the non-canonical length of CDR2β is a critical determinant for recognition by TSST-1 as well as the distantly related SAg streptococcal pyrogenic exotoxin C. Frame work (FR) region 3 is uniquely critical for TSST-1 function explaining the fine Vβ-specificity exhibited by this SAg. Furthermore, domain swapping experiments with SAgs, which use distinct domains to engage both CDR2β and FR3/4β revealed that the CDR2β contacts dictate T lymphocyte Vβ-specificity. These findings demonstrate that the TCR CDR2β loop is the critical determinant for functional recognition and Vβ-specificity by diverse bacterial SAgs.
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Affiliation(s)
- A K M Nur-ur Rahman
- Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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21
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The structure of superantigen complexed with TCR and MHC reveals novel insights into superantigenic T cell activation. Nat Commun 2010; 1:119. [PMID: 21081917 DOI: 10.1038/ncomms1117] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 10/18/2010] [Indexed: 11/09/2022] Open
Abstract
Superantigens (SAgs) are bacterial toxins that interact with immunoreceptors, T cell receptor (TCR) and major histocompatibility complex (MHC) class II, conventionally through the variable β-domain of TCR (TCRVβ). They induce a massive release of cytokines, which can lead to diseases such as food poisoning and toxic shock syndrome. In this study, we report the X-ray structure of the ternary complex between staphylococcal enterotoxin H (SEH) and its human receptors, MHC class II and TCR. The structure demonstrates that SEH predominantly interacts with the variable α-domain of TCR (TCRVα), which is supported by nuclear magnetic resonance (NMR) analyses. Furthermore, there is no contact between MHC and TCR upon complex formation. Structural analyses suggest that the major contact points to TCRVα are conserved among other bacterial SAgs. Consequently, a new dimension of SAg biology emerges, suggesting that in addition to the conventional interactions with the TCRVβ domain, SAgs can also activate T cells through the TCRVα domain.
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22
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Identification of three novel superantigen-encoding genes in Streptococcus equi subsp. zooepidemicus, szeF, szeN, and szeP. Infect Immun 2010; 78:4817-27. [PMID: 20713629 DOI: 10.1128/iai.00751-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The acquisition of superantigen-encoding genes by Streptococcus pyogenes has been associated with increased morbidity and mortality in humans, and the gain of four superantigens by Streptococcus equi is linked to the evolution of this host-restricted pathogen from an ancestral strain of the opportunistic pathogen Streptococcus equi subsp. zooepidemicus. A recent study determined that the culture supernatants of several S. equi subsp. zooepidemicus strains possessed mitogenic activity but lacked known superantigen-encoding genes. Here, we report the identification and activities of three novel superantigen-encoding genes. The products of szeF, szeN, and szeP share 59%, 49%, and 34% amino acid sequence identity with SPEH, SPEM, and SPEL, respectively. Recombinant SzeF, SzeN, and SzeP stimulated the proliferation of equine peripheral blood mononuclear cells, and tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) production, in vitro. Although none of these superantigen genes were encoded within functional prophage elements, szeN and szeP were located next to a prophage remnant, suggesting that they were acquired by horizontal transfer. Eighty-one of 165 diverse S. equi subsp. zooepidemicus strains screened, including 7 out of 15 isolates from cases of disease in humans, contained at least one of these new superantigen-encoding genes. The presence of szeN or szeP, but not szeF, was significantly associated with mitogenic activity in the S. equi subsp. zooepidemicus population (P < 0.000001, P < 0.000001, and P = 0.104, respectively). We conclude that horizontal transfer of these novel superantigens from and within the diverse S. equi subsp. zooepidemicus population is likely to have implications for veterinary and human disease.
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23
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Kasper KJ, Xi W, Rahman AKMNU, Nooh MM, Kotb M, Sundberg EJ, Madrenas J, McCormick JK. Molecular requirements for MHC class II alpha-chain engagement and allelic discrimination by the bacterial superantigen streptococcal pyrogenic exotoxin C. THE JOURNAL OF IMMUNOLOGY 2008; 181:3384-92. [PMID: 18714010 DOI: 10.4049/jimmunol.181.5.3384] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Superantigens (SAgs) are microbial toxins that bind to both TCR beta-chain variable domains (Vbetas) and MHC class II molecules, resulting in the activation of T cells in a Vbeta-specific manner. It is now well established that different isoforms of MHC II molecules can play a significant role in the immune response to bacterial SAgs. In this work, using directed mutational studies in conjunction with functional analyses, we provide a complete functional map of the low-affinity MHC II alpha-chain binding interface of the SAg streptococcal pyrogenic exotoxin C (SpeC) and identify a functional epitope in the beta-barrel domain that is required for the activation of T cells. Using cell lines that exclusively express individual MHC II isoforms, our studies provide a molecular basis for the selectivity of SpeC-MHC II recognition, and provide one mechanism by how SAgs are capable of distinguishing between different MHC II alleles.
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Affiliation(s)
- Katherine J Kasper
- Department of Microbiology and Immunology, University of Western Ontario, Canada
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24
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El Ferezli J, Jenbazian L, Rubeiz N, Kibbi AG, Zaynoun S, Abdelnoor AM. Streptococcus sp. and Staphylococcus aureus isolates from patients with psoriasis possess genes that code for toxins (superantigens): clinical and therapeutic implications. Immunopharmacol Immunotoxicol 2008; 30:195-205. [PMID: 18569077 DOI: 10.1080/08923970801946808] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Superantigens are powerful T lymphocyte-stimulating agents that are believed to contribute to the pathogenesis of certain diseases such as psoriasis. Toxins produced by Streptococcus pyogenes and Staphylococcus aureus are superantigens. The aim of this study was to detect genes that code for superantigens in Streptococcus and Staphylococcus aureus isolates from psoriatic patients. Primers to amplify streptococcal pyrogenic exotoxin A, B, and C and streptolysin O genes and staphylococcal enterotoxin A, B, C, and D genes were used. Streptococcal exotoxin B was detected in five streptococcal isolates. Staphyloccocus aureus enterotoxin A and/or C genes were detected in nine S. aureus isolates. Isolates from 13 of 22 patients possesed gene(s) that code for toxin(s) (superantigens). These results might support the role of superantigens in the exacerbation of psoriasis.
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Affiliation(s)
- Jessica El Ferezli
- Department of Microbiology and Immunology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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25
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Saarinen S, Kato H, Uchiyama T, Miyoshi-Akiyama T, Papageorgiou AC. Crystal Structure of Streptococcus dysgalactiae-Derived Mitogen Reveals a Zinc-Binding Site and Alterations in TcR Binding. J Mol Biol 2007; 373:1089-97. [PMID: 17900619 DOI: 10.1016/j.jmb.2007.08.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 08/13/2007] [Accepted: 08/14/2007] [Indexed: 11/25/2022]
Abstract
Bacterial superantigens are protein toxins with an ability to cause serious diseases in humans by activating a large number of T cells. Streptococcus dysgalactiae-derived mitogen (SDM) is a novel superantigen that is distinct from other known superantigens based on phylogenetic analysis. The X-ray structure of SDM has been determined at 1.95 A resolution. SDM shares the same characteristic fold with other superantigens, but it shows a major structural difference due to the lack of the alpha5 helix between the beta10 and beta11 strands. A bound zinc ion was identified in the structure at the C-terminal domain of the molecule. SDM appears to bind to the major histocompatibility complex class II beta-chain through the zinc-binding site, as described by mutagenesis data and structural comparisons. T-cell binding instead shows a significant difference compared to other superantigens. The mutation of Asn11 (a conserved residue that is known to be significant for T-cell-receptor binding in other superantigens) and Lys15 to Ala did not cause any decrease in the mitogenic activity of SDM. This observation and the lack of the alpha5 helix suggest alterations in T-cell-receptor binding.
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Affiliation(s)
- Susanna Saarinen
- Turku Center for Biotechnology, University of Turku and Abo Akademi University, PO Box 123, Tykistökatu 6, BioCity, Turku 20521, Finland
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26
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Sundberg EJ, Deng L, Mariuzza RA. TCR recognition of peptide/MHC class II complexes and superantigens. Semin Immunol 2007; 19:262-71. [PMID: 17560120 PMCID: PMC2949352 DOI: 10.1016/j.smim.2007.04.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 04/23/2007] [Accepted: 04/23/2007] [Indexed: 11/21/2022]
Abstract
Major histocompatibility complex (MHC) class II molecules display peptides to the T cell receptor (TCR). The ability of the TCR to discriminate foreign from self-peptides presented by MHC molecules is a requirement of an effective adaptive immune response. Dysregulation of this molecular recognition event often leads to a disease state. Recently, a number of structural studies have provided significant insight into several such dysregulated interactions between peptide/MHC complexes and TCR molecules. These include TCR recognition of self-peptides, which results in autoimmune reactions, and of mutant self-peptides, common in the immunosurveillance of tumors, as well as the engagement of TCRs by superantigens, a family of bacterial toxins responsible for toxic shock syndrome.
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Affiliation(s)
- Eric J Sundberg
- Boston Biomedical Research Institute, Watertown, MA 02472, USA.
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27
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Günther S, Varma AK, Moza B, Kasper KJ, Wyatt AW, Zhu P, Rahman AKMNU, Li Y, Mariuzza RA, McCormick JK, Sundberg EJ. A novel loop domain in superantigens extends their T cell receptor recognition site. J Mol Biol 2007; 371:210-21. [PMID: 17560605 PMCID: PMC2949350 DOI: 10.1016/j.jmb.2007.05.038] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 05/10/2007] [Accepted: 05/11/2007] [Indexed: 10/23/2022]
Abstract
Superantigens (SAGs) interact with host immune receptors to induce a massive release of inflammatory cytokines that can lead to toxic shock syndrome and death. Bacterial SAGs can be classified into five distinct evolutionary groups. Group V SAGs are characterized by the alpha3-beta8 loop, a unique approximately 15 amino acid residue extension that is required for optimal T cell activation. Here, we report the X-ray crystal structures of the group V SAG staphylococcal enterotoxin K (SEK) alone and in complex with the TCR hVbeta5.1 domain. SEK adopts a unique TCR binding orientation relative to other SAG-TCR complexes, which results in the alpha3-beta8 loop contacting the apical loop of framework region 4, thereby extending the known TCR recognition site of SAGs. These interactions are absolutely required for TCR binding and T cell activation by SEK, and dictate the TCR Vbeta domain specificity of SEK and other group V SAGs.
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MESH Headings
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Crystallography, X-Ray
- Enterotoxins/chemistry
- Enterotoxins/immunology
- Humans
- Models, Molecular
- Protein Binding
- Protein Structure, Tertiary
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Signal Transduction/physiology
- Staphylococcus aureus/immunology
- Superantigens/chemistry
- Superantigens/genetics
- Superantigens/immunology
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