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Wong Fok Lung T, Chan LC, Prince A, Yeaman MR, Archer NK, Aman MJ, Proctor RA. Staphylococcus aureus adaptive evolution: Recent insights on how immune evasion, immunometabolic subversion and host genetics impact vaccine development. Front Cell Infect Microbiol 2022; 12:1060810. [PMID: 36636720 PMCID: PMC9831658 DOI: 10.3389/fcimb.2022.1060810] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/16/2022] [Indexed: 12/28/2022] Open
Abstract
Despite meritorious attempts, a S. aureus vaccine that prevents infection or mitigates severity has not yet achieved efficacy endpoints in prospective, randomized clinical trials. This experience underscores the complexity of host-S. aureus interactions, which appear to be greater than many other bacterial pathogens against which successful vaccines have been developed. It is increasingly evident that S. aureus employs strategic countermeasures to evade or exploit human immune responses. From entering host cells to persist in stealthy intracellular reservoirs, to sensing the environmental milieu and leveraging bacterial or host metabolic products to reprogram host immune responses, S. aureus poses considerable challenges for the development of effective vaccines. The fact that this pathogen causes distinct types of infections and can undergo transient genetic, transcriptional or metabolic adaptations in vivo that do not occur in vitro compounds challenges in vaccine development. Notably, the metabolic versatility of both bacterial and host immune cells as they compete for available substrates within specific tissues inevitably impacts the variable repertoire of gene products that may or may not be vaccine antigens. In this respect, S. aureus has chameleon phenotypes that have alluded vaccine strategies thus far. Nonetheless, a number of recent studies have also revealed important new insights into pathogenesis vulnerabilities of S. aureus. A more detailed understanding of host protective immune defenses versus S. aureus adaptive immune evasion mechanisms may offer breakthroughs in the development of effective vaccines, but at present this goal remains a very high bar. Coupled with the recent advances in human genetics and epigenetics, newer vaccine technologies may enable such a goal. If so, future vaccines that protect against or mitigate the severity of S. aureus infections are likely to emerge at the intersection of precision and personalized medicine. For now, the development of S. aureus vaccines or alternative therapies that reduce mortality and morbidity must continue to be pursued.
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Affiliation(s)
| | - Liana C Chan
- Department of Medicine, David Geffen School of Medicine at University of California Loss Angeles (UCLA), Los Angeles, CA, United States.,Divisions of Molecular Medicine and Infectious Diseases, Harbor-University of California Loss Angeles (UCLA) Medical Center, Torrance, CA, United States.,Lundquist Institute for Biomedical Innovation at Harbor-University of California Loss Angeles (UCLA) Medical Center, Torrance, CA, United States
| | - Alice Prince
- Department of Pediatrics, Columbia University, New York, NY, United States
| | - Michael R Yeaman
- Department of Medicine, David Geffen School of Medicine at University of California Loss Angeles (UCLA), Los Angeles, CA, United States.,Divisions of Molecular Medicine and Infectious Diseases, Harbor-University of California Loss Angeles (UCLA) Medical Center, Torrance, CA, United States.,Lundquist Institute for Biomedical Innovation at Harbor-University of California Loss Angeles (UCLA) Medical Center, Torrance, CA, United States
| | - Nathan K Archer
- Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - M Javad Aman
- Integrated BioTherapeutics, Rockville, MD, United States
| | - Richard A Proctor
- Department of Medicine and Medical Microbiology/Immunology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
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2
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Pichon M, Micaelo M, Rasoanandrasana S, Menn AM. Molecular characterization of Staphylococcus aureus isolates derived from severe pneumonia: a retrospective monocentre study. Infect Dis (Lond) 2021; 53:811-819. [PMID: 34382901 DOI: 10.1080/23744235.2021.1963472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Staphylococcus aureus is endowed with a repertoire of virulence factors potentially implicated in its pathogenicity and ability to cause invasive disease. The main objective of this study was to describe the bacterial genotype, including virulence genes and affiliation to clonal complexes (CCs), encountered in severe pneumonia. METHODS DNA microarray was used to analyse 18 S. aureus isolates from patients hospitalized with severe pneumonia between 2017 and 2019. RESULTS Among 18 S. aureus isolates, 14 were methicillin-susceptible S. aureus (MSSA), and 4 methicillin-resistant S. aureus (MRSA). There were 14 community-acquired, 3 healthcare-associated, and 1 hospital-acquired infections. Different radiological presentations were observed: necrotizing pneumonia (n = 8, 44%), alveolar consolidation (n = 7, 39%), alveolar-interstitial infiltrates (n = 3, 17%). Sixteen patients (89%) required ICU hospitalization, 13 (72%) an invasive mechanical ventilation, and 12 (67%) a vasopressor support. Mortality affected 6 patients (33%). Panton-Valentine leukocidin (PVL), staphylococcal enterotoxins, toxic shock syndrome toxine-1 (TSST-1) encoding genes were documented in nine (50%), 12 (67%), one (6%) of the isolates, respectively. Accessory regulator gene group I was the most reported (n = 9, 50%) and was found in five deaths. The majority of isolates were affiliated to CC152 (n = 6), followed by CC15 (n = 3), CC45 (n = 2), CC30 (n = 2), CC1 (n = 2), CC8 (n = 1), CC9 (n = 1), and CC25 (n = 1). All the CC152 isolates were PVL-positive. CONCLUSION CC152-PVL positive S. aureus strains were the most prevalent in severe pneumonia. Other virulence gene profiles were found coupled to additional clonal lineages. A genotyping strategy contributes to describe the current circulating strains and bacterial genetic backgrounds.
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Affiliation(s)
- Maud Pichon
- Service de Médecine Polyvalente, Centre Hospitalier Victor Dupouy, Argenteuil, France
| | - Maïte Micaelo
- Service de Microbiologie, Centre Hospitalier Victor Dupouy, Argenteuil, France
| | | | - Anne-Marie Menn
- Service de Médecine Polyvalente, Centre Hospitalier Victor Dupouy, Argenteuil, France
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3
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Miller LS, Fowler VG, Shukla SK, Rose WE, Proctor RA. Development of a vaccine against Staphylococcus aureus invasive infections: Evidence based on human immunity, genetics and bacterial evasion mechanisms. FEMS Microbiol Rev 2020; 44:123-153. [PMID: 31841134 PMCID: PMC7053580 DOI: 10.1093/femsre/fuz030] [Citation(s) in RCA: 126] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/13/2019] [Indexed: 12/12/2022] Open
Abstract
Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.
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Affiliation(s)
- Lloyd S Miller
- Immunology, Janssen Research and Development, 1400 McKean Road, Spring House, PA, 19477, USA.,Department of Dermatology, Johns Hopkins University School of Medicine, 1550 Orleans Street, Cancer Research Building 2, Suite 209, Baltimore, MD, 21231, USA.,Department of Medicine, Division of Infectious Diseases, Johns Hopkins University School of Medicine, 1830 East Monument Street, Baltimore, MD, 21287, USA.,Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, 601 North Caroline Street, Baltimore, MD, 21287, USA.,Department of Materials Science and Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA
| | - Vance G Fowler
- Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, 315 Trent Drive, Hanes House, Durham, NC, 27710, USA.,Duke Clinical Research Institute, Duke University Medical Center, 40 Duke Medicine Circle, Durham, NC, 27710, USA
| | - Sanjay K Shukla
- Center for Precision Medicine Research, Marshfield Clinic Research Institute, 1000 North Oak Avenue, Marshfield, WI, 54449, USA.,Computation and Informatics in Biology and Medicine, University of Wisconsin, 425 Henry Mall, Room 3445, Madison, WI, 53706, USA
| | - Warren E Rose
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, 1685 Highland Avenue, 5158 Medical Foundation Centennial Building, Madison, WI, 53705, USA.,Pharmacy Practice Division, University of Wisconsin-Madison, 777 Highland Avenue, 4123 Rennebohm Hall, Madison, WI, 53705 USA
| | - Richard A Proctor
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, 1685 Highland Avenue, 5158 Medical Foundation Centennial Building, Madison, WI, 53705, USA.,Department of Medical Microbiology and Immunology, University of Wisconsin-Madison School of Medicine and Public Health, 1550 Linden Drive, Microbial Sciences Building, Room 1334, Madison, WI, 53705, USA
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4
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Dendritic Cells Internalize Staphylococcus aureus More Efficiently than Staphylococcus epidermidis, but Do Not Differ in Induction of Antigen-Specific T Cell Proliferation. Microorganisms 2019; 8:microorganisms8010019. [PMID: 31861881 PMCID: PMC7022728 DOI: 10.3390/microorganisms8010019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/05/2019] [Accepted: 12/18/2019] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus and Staphylococcus epidermidis are related species which can cause predominantly acute and subacute infections, respectively. Differences in human adaptive immune responses to these two species are not well understood. Dendritic cells (DCs) have an important role in the control and regulation of anti-staphylococcal T cell responses. Therefore, we aimed to compare the ability of S. aureus and S. epidermidis to influence the essential steps in human DC activation and subsequent antigen-specific CD4+ T cell proliferation, and to investigate the underlying mechanisms. Using multiple strains of both species, we observed that S. aureus was internalized more effectively than S. epidermidis by DCs but that both species were equally potent in activating these host cells, as evidenced by similar induction of DC maturation marker expression and antigen loading onto MHC-II molecules. The DCs stimulated by S. aureus strains not harboring superantigen (SAg) genes or by any of the S. epidermidis strains, induced low, likely physiological levels of T cell proliferation. Only DCs stimulated with S. aureus strains harboring SAg genes induced high levels of T cell proliferation. Taken together, S. aureus and S. epidermidis do not differently affect DC activation and ensuing antigen-specific T cell proliferation, unless a strain has the capacity to produce SAgs.
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5
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TBA 225, a fusion toxoid vaccine for protection and broad neutralization of staphylococcal superantigens. Sci Rep 2019; 9:3279. [PMID: 30824769 PMCID: PMC6397225 DOI: 10.1038/s41598-019-39890-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 12/04/2018] [Indexed: 02/01/2023] Open
Abstract
Superantigens (SAgs) play a major role in the pathogenesis of Staphylococcus aureus and are associated with several diseases, including food poisoning, bacterial arthritis, and toxic shock syndrome. Monoclonal antibodies to these SAgs, primarily TSST-1, SEB and SEA have been shown to provide protection in animal studies and to reduce clinical severity in bacteremic patients. Here we quantify the pre-existing antibodies against SAgs in many human plasma and IVIG samples and demonstrate that in a major portion of the population these antibody titers are suboptimal and IVIG therapy only incrementally elevates the anti-SAg titers. Our in vitro neutralization studies show that a combination of antibodies against SEA, SEB,and TSST-1 can provide broad neutralization of staphylococcal SAgs. We report a single fusion protein (TBA225) consisting of the toxoid versions of TSST-1, SEB and SEA and demonstrate its immunogenicity and protective efficacy in a mouse model of toxic shock. Antibodies raised against this fusion vaccine provide broad neutralization of purified SAgs and culture supernatants of multiple clinically relevant S. aureus strains. Our data strongly supports the use of this fusion protein as a component of an anti-virulence based multivalent toxoid vaccine against S. aureus disease.
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6
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He C, Xu S, Zhao H, Hu F, Xu X, Jin S, Yang H, Gong F, Liu Q. Leukotoxin and pyrogenic toxin Superantigen gene backgrounds in bloodstream and wound Staphylococcus aureus isolates from eastern region of China. BMC Infect Dis 2018; 18:395. [PMID: 30103694 PMCID: PMC6090790 DOI: 10.1186/s12879-018-3297-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 08/01/2018] [Indexed: 11/10/2022] Open
Abstract
Background The bicomponent leukotoxins and the pyrogenic toxin superantigens (PTSAgs) are important virulence factors of Staphylococcus aureus. It is necessary to survey the prevalence and expression of these toxin-encoding genes for understanding the possible pathogenic capacity of S. aureus to cause disease. Methods Five leukotoxin genes and thirteen PTSAg determinants were detected for 177 S. aureus isolates from blood (n = 88) and wound (n = 89) infections by Polymerase Chain Reaction (PCR). The expression of leukotoxin ED (lukED) was determined by quantitative real-time PCR (qRT-PCR). The genetic backgrounds of isolates were analyzed by Staphylococcal Cassette Chromosome mec (SCCmec) typing (for methicillin-resistant S. aureus isolates), Pulsed-Field Gel Electrophoresis (PFGE), accessory gene regulator (agr) typing and Multilocus Sequence Typing (MLST, for representative isolates based on PFGE type) methods. Results 99.4% (176/177) isolates contained at least one of leukotoxin genes. Among them, 94.9% (168/177), 81.4% (144/177) and 67.8% (120/177) isolates harbored hlgBC, lukED and lukAB, respectively. Compared to leukotoxin genes, there was a relatively lower overall prevalence of PTSAg genes [99.4% versus 72.9% (129/177), P < 0.001], and they were organized in 59 patterns, with the most common combination of the egc cluster with or without other PTSAg genes. Genetic analysis showed the distributions of certain toxin genes were associated with the genetic backgrounds of isolates. The egc cluster was a common feature of CC5 isolates, among which ST5 and ST764 isolates harbored more PTSAg genes. The lukED was not present in ST398 isolates, and its expression was quite different among isolates. No significant correlations were observed between the lukED expression levels of strains and the ST or agr types. Conclusions The present study elucidated the distribution of leukotoxin and PTSAg genes and the expression of lukED in blood and wound isolates, and analyzed the relationship between them with genetic characteristics of isolates. These data improve the current understanding of the possible pathogenicity of S. aureus. Electronic supplementary material The online version of this article (10.1186/s12879-018-3297-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chunyan He
- Department of Clinical Laboratory, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200080, China
| | - Su Xu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, 200080, China
| | - Huanqiang Zhao
- Department of Clinical Laboratory, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200080, China
| | - Fupin Hu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, 200080, China
| | - Xiaogang Xu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, 200080, China
| | - Shu Jin
- Experimental Research Center, Shanghai People's Hospital of Putuo District, Shanghai, 200080, China
| | - Han Yang
- Department of Clinical Laboratory, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200080, China
| | - Fang Gong
- Department of Clinical Laboratory, the Third Hospital Affiliated to Nantong University, Wuxi, 226000, China
| | - Qingzhong Liu
- Department of Clinical Laboratory, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200080, China.
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7
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Svedova J, Ménoret A, Mittal P, Ryan JM, Buturla JA, Vella AT. Therapeutic blockade of CD54 attenuates pulmonary barrier damage in T cell-induced acute lung injury. Am J Physiol Lung Cell Mol Physiol 2017; 313:L177-L191. [PMID: 28473322 DOI: 10.1152/ajplung.00050.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 04/27/2017] [Accepted: 04/27/2017] [Indexed: 12/19/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is a serious, often fatal condition without available pharmacotherapy. Although the role of innate cells in ARDS has been studied extensively, emerging evidence suggests that T cells may be involved in disease etiology. Staphylococcus aureus enterotoxins are potent T-cell mitogens capable of triggering life-threatening shock. We demonstrate that 2 days after inhalation of S. aureus enterotoxin A, mice developed T cell-mediated increases in vascular permeability, as well as expression of injury markers and caspases in the lung. Pulmonary endothelial cells underwent sequential phenotypic changes marked by rapid activation coinciding with inflammatory events secondary to T-cell priming, followed by reductions in endothelial cell number juxtaposing simultaneous T-cell expansion and cytotoxic differentiation. Although initial T-cell activation influenced the extent of lung injury, CD54 (ICAM-1) blocking antibody administered well after enterotoxin exposure substantially attenuated pulmonary barrier damage. Thus CD54-targeted therapy may be a promising candidate for further exploration into its potential utility in treating ARDS patients.
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Affiliation(s)
- Julia Svedova
- Department of Immunology, School of Medicine, UConn Health, Farmington, Connecticut
| | - Antoine Ménoret
- Department of Immunology, School of Medicine, UConn Health, Farmington, Connecticut.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut; and
| | - Payal Mittal
- Department of Immunology, School of Medicine, UConn Health, Farmington, Connecticut
| | - Joseph M Ryan
- Department of Immunology, School of Medicine, UConn Health, Farmington, Connecticut
| | - James A Buturla
- Department of Internal Medicine, UConn Health, Farmington, Connecticut
| | - Anthony T Vella
- Department of Immunology, School of Medicine, UConn Health, Farmington, Connecticut;
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8
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Szabo PA, Goswami A, Mazzuca DM, Kim K, O'Gorman DB, Hess DA, Welch ID, Young HA, Singh B, McCormick JK, Haeryfar SMM. Rapid and Rigorous IL-17A Production by a Distinct Subpopulation of Effector Memory T Lymphocytes Constitutes a Novel Mechanism of Toxic Shock Syndrome Immunopathology. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2017; 198:2805-2818. [PMID: 28219889 PMCID: PMC6635948 DOI: 10.4049/jimmunol.1601366] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/25/2017] [Indexed: 01/13/2023]
Abstract
Toxic shock syndrome (TSS) is caused by staphylococcal and streptococcal superantigens (SAgs) that provoke a swift hyperinflammatory response typified by a cytokine storm. The precipitous decline in the host's clinical status and the lack of targeted therapies for TSS emphasize the need to identify key players of the storm's initial wave. Using a humanized mouse model of TSS and human cells, we herein demonstrate that SAgs elicit in vitro and in vivo IL-17A responses within hours. SAg-triggered human IL-17A production was characterized by remarkably high mRNA stability for this cytokine. A distinct subpopulation of CD4+ effector memory T (TEM) cells that secrete IL-17A, but not IFN-γ, was responsible for early IL-17A production. We found mouse "TEM-17" cells to be enriched within the intestinal epithelium and among lamina propria lymphocytes. Furthermore, interfering with IL-17A receptor signaling in human PBMCs attenuated the expression of numerous inflammatory mediators implicated in the TSS-associated cytokine storm. IL-17A receptor blockade also abrogated the secondary effect of SAg-stimulated PBMCs on human dermal fibroblasts as judged by C/EBP δ expression. Finally, the early IL-17A response to SAgs was pathogenic because in vivo neutralization of IL-17A in humanized mice ameliorated hepatic and intestinal damage and reduced mortality. Together, our findings identify CD4+ TEM cells as a key effector of TSS and reveal a novel role for IL-17A in TSS immunopathogenesis. Our work thus elucidates a pathogenic, as opposed to protective, role for IL-17A during Gram-positive bacterial infections. Accordingly, the IL-17-IL-17R axis may provide an attractive target for the management of SAg-mediated illnesses.
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Affiliation(s)
- Peter A Szabo
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada
| | - Ankur Goswami
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada
| | - Delfina M Mazzuca
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada
| | - Kyoungok Kim
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada
| | - David B O'Gorman
- Cell and Molecular Biology Laboratory, Roth | McFarlane Hand and Upper Limb Centre, Western University, London, Ontario N6A 4V2, Canada
- Department of Biochemistry, Western University, London, Ontario N6A 5C1, Canada
- Lawson Health Research Institute, London, Ontario N6C 2R5, Canada
- Department of Surgery, Western University, London, Ontario N6A 4V2, Canada
| | - David A Hess
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Krembil Centre for Stem Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, London, Ontario N6A 5B7, Canada
| | - Ian D Welch
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia V6T 2B5, Canada
| | - Howard A Young
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702
| | - Bhagirath Singh
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada
- Lawson Health Research Institute, London, Ontario N6C 2R5, Canada
- Centre for Human Immunology, Western University, London, Ontario N6A 5C1, Canada; and
| | - John K McCormick
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada
- Lawson Health Research Institute, London, Ontario N6C 2R5, Canada
- Centre for Human Immunology, Western University, London, Ontario N6A 5C1, Canada; and
| | - S M Mansour Haeryfar
- Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada;
- Lawson Health Research Institute, London, Ontario N6C 2R5, Canada
- Centre for Human Immunology, Western University, London, Ontario N6A 5C1, Canada; and
- Division of Clinical Immunology and Allergy, Department of Medicine, Western University, London, Ontario N6A 5A5, Canada
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9
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Svedova J, Tsurutani N, Liu W, Khanna KM, Vella AT. TNF and CD28 Signaling Play Unique but Complementary Roles in the Systemic Recruitment of Innate Immune Cells after Staphylococcus aureus Enterotoxin A Inhalation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:4510-21. [PMID: 27183621 PMCID: PMC4875807 DOI: 10.4049/jimmunol.1600113] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 03/27/2016] [Indexed: 01/12/2023]
Abstract
Staphylococcus aureus enterotoxins cause debilitating systemic inflammatory responses, but how they spread systemically and trigger inflammatory cascade is unclear. In this study, we showed in mice that after inhalation, Staphylococcus aureus enterotoxin A rapidly entered the bloodstream and induced T cells to orchestrate systemic recruitment of inflammatory monocytes and neutrophils. To study the mechanism used by specific T cells that mediate this process, a systems approach revealed inducible and noninducible pathways as potential targets. It was found that TNF caused neutrophil entry into the peripheral blood, whereas CD28 signaling, but not TNF, was needed for chemotaxis of inflammatory monocytes into blood and lymphoid tissue. However, both pathways triggered local recruitment of neutrophils into lymph nodes. Thus, our findings revealed a dual mechanism of monocyte and neutrophil recruitment by T cells relying on overlapping and nonoverlapping roles for the noninducible costimulatory receptor CD28 and the inflammatory cytokine TNF. During sepsis, there might be clinical value in inhibiting CD28 signaling to decrease T cell-mediated inflammation and recruitment of innate cells while retaining bioactive TNF to foster neutrophil circulation.
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Affiliation(s)
- Julia Svedova
- Department of Immunology, School of Medicine, UConn Health, Farmington, CT 06030
| | - Naomi Tsurutani
- Department of Immunology, School of Medicine, UConn Health, Farmington, CT 06030
| | - Wenhai Liu
- Department of Immunology, School of Medicine, UConn Health, Farmington, CT 06030
| | - Kamal M Khanna
- Department of Immunology, School of Medicine, UConn Health, Farmington, CT 06030
| | - Anthony T Vella
- Department of Immunology, School of Medicine, UConn Health, Farmington, CT 06030
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10
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Abstract
Staphylococcal enterotoxin B is one of the most potent bacterial superantigens that exerts profound toxic effects upon the immune system, leading to stimulation of cytokine release and inflammation. It is associated with food poisoning, nonmenstrual toxic shock, atopic dermatitis, asthma, and nasal polyps in humans. Currently, there is no treatment or vaccine available. Passive immunotherapy using monoclonal antibodies made in several different species has shown significant inhibition in in vitro studies and reduction in staphylococcal enterotoxin B-induced lethal shock in in vivo studies. This should encourage future endeavors to develop these antibodies as therapeutic reagents.
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11
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Prindeze NJ, Amundsen BM, Pavlovich AR, Paul DW, Carney BC, Moffatt LT, Shupp JW. Staphylococcal superantigens and toxins are detectable in the serum of adult burn patients. Diagn Microbiol Infect Dis 2014; 79:303-7. [PMID: 24809857 DOI: 10.1016/j.diagmicrobio.2014.01.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 01/25/2023]
Abstract
Bacterial infection in burn patients is still a devastating contributor to morbidity and mortality. Little is known regarding the presence of staphylococcal toxins in the burn-injured patient. The aim of this study was to characterize the prevalence of several of these toxins and their relationship to clinical metrics and mortality in burn patients. Levels of exotoxins staphylococcal enterotoxin A (SEA), staphylococcal enterotoxin B, toxic shock syndrome toxin 1 (TSST-1), and α-hemolysin were assayed from the serum of 207 adult burn patients aged 16-92 years. Clinical, demographic, and microbiological data from these patients were then compared to toxin levels. Staphylococcal exotoxins α-hemolysin and SEA were present in 45% and 25% of the population, respectively. Bacterial cultures concomitantly showed a high prevalence of Staphylococcus aureus in 48% of patients, of which 59% were methicillin resistant. Several metrics may be predictive of high toxin concentrations of α-hemolysin and TSST-1 and SEA including burn size, length of stay, and bacteremia. Mortality associations indicated that burn size, bacteremia, age, and the presence of α-hemolysin and SEA may be predictors of mortality. A high prevalence of staphylococcal toxin α-hemolysin and superantigens TSST-1 and SEA can be found in the circulation of the adult burn population. The presence of these toxins may contribute to the morbidity and mortality of the burn patient.
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Affiliation(s)
- Nicholas J Prindeze
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975
| | - Bethany M Amundsen
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975
| | - Anna R Pavlovich
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975
| | - Dereck W Paul
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975
| | - Bonnie C Carney
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975
| | - Lauren T Moffatt
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975
| | - Jeffrey W Shupp
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, MedStar Health Research Institute, 110 Irving Street NW, Washington, DC 20010-2975.
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Streptococcal superantigens: categorization and clinical associations. Trends Mol Med 2013; 20:48-62. [PMID: 24210845 DOI: 10.1016/j.molmed.2013.10.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 10/01/2013] [Accepted: 10/08/2013] [Indexed: 01/01/2023]
Abstract
Superantigens are key virulence factors in the immunopathogenesis of invasive disease caused by group A streptococcus. These protein exotoxins have also been associated with severe group C and group G streptococcal infections. A number of novel streptococcal superantigens have recently been described with some resulting confusion in their classification. In addition to clarifying the nomenclature of streptococcal superantigens and proposing guidelines for their categorization, this review summarizes the evidence supporting their involvement in various clinical diseases including acute rheumatic fever.
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13
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Kissner TL, Ruthel G, Alam S, Mann E, Ajami D, Rebek M, Larkin E, Fernandez S, Ulrich RG, Ping S, Waugh DS, Rebek J, Saikh KU. Therapeutic inhibition of pro-inflammatory signaling and toxicity to staphylococcal enterotoxin B by a synthetic dimeric BB-loop mimetic of MyD88. PLoS One 2012; 7:e40773. [PMID: 22848400 PMCID: PMC3407147 DOI: 10.1371/journal.pone.0040773] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 06/13/2012] [Indexed: 11/18/2022] Open
Abstract
Staphylococcal enterotoxin B (SEB) exposure triggers an exaggerated pro-inflammatory cytokine response that often leads to toxic shock syndrome (TSS) associated with organ failure and death. MyD88 mediates pro-inflammatory cytokine signaling induced by SEB exposure and MyD88(-/-) mice are resistant to SEB intoxication, suggesting that MyD88 may be a potential target for therapeutic intervention. We targeted the BB loop region of the Toll/IL-1 receptor (TIR) domain of MyD88 to develop small-molecule therapeutics. Here, we report that a synthetic compound (EM-163), mimic to dimeric form of BB-loop of MyD88 attenuated tumor necrosis factor (TNF)- α, interferon (IFN)-γ, interleukin (IL)-1β, IL-2 and IL-6 production in human primary cells, whether administered pre- or post-SEB exposure. Results from a direct binding assay, and from MyD88 co-transfection/co-immunoprecipitation experiments, suggest that EM-163 inhibits TIR-TIR domain interaction. Additional results indicate that EM-163 prevents MyD88 from mediating downstream signaling. In an NF-kB-driven reporter assay of lipopolysaccharide-stimulated MyD88 signaling, EM-163 demonstrated a dose-dependent inhibition of reporter activity as well as TNF-α and IL-1β production. Importantly, administration of EM-163 pre- or post exposure to a lethal dose of SEB abrogated pro-inflammatory cytokine responses and protected mice from toxic shock-induced death. Taken together, our results suggest that EM-163 exhibits a potential for therapeutic use against SEB intoxication.
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Affiliation(s)
- Teri L. Kissner
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Gordon Ruthel
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Shahabuddin Alam
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Enrique Mann
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Dariush Ajami
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Mitra Rebek
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Eileen Larkin
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Stefan Fernandez
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Robert G. Ulrich
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Sun Ping
- Macromolecular Crystallography Laboratory, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - David S. Waugh
- Macromolecular Crystallography Laboratory, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Julius Rebek
- Macromolecular Crystallography Laboratory, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Kamal U. Saikh
- Department of Immunology, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- * E-mail:
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Biological and technical considerations regarding the removal of bacteriotoxins in sepsis with emphasis on toxic shock syndrome toxin 1. Shock 2012; 37:247-52. [PMID: 22129566 DOI: 10.1097/shk.0b013e3182429b38] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Severe sepsis is characterized by rapid development of multiple organ failure associated with high mortality. Bacterial toxin release triggers a sequence of events that activates intracellular pathways to produce inflammatory mediators and nitric oxide. There have been numerous attempts to interrupt this devastating cascade by removing toxins, removing or inhibiting mediators, and by blocking receptors of mediators. This review considers toxin properties with a strong focus on toxic shock syndrome toxin 1 and the potential of various removal technologies in relation to these properties. The distribution of toxins in vivo forms a key issue but is nevertheless poorly defined. For toxic shock syndrome toxin 1, either a high clearance or a high degree of compartmentalization to a space not accessible by pheresis or immunoabsorption technologies seems likely. Attempts to remove toxins to treat sepsis may appear futile if we cannot access this space or when the level of induced clearance is too low compared with natural clearance. The impact of these considerations is highly dependent on the exact toxin biology in vivo. Extrapolated to other toxins, we indicate a set of general requirements to be met to facilitate successful toxin removal by a pheresis technique.
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15
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Xiao Z, Wu L, Mo H, Kong T. Increased T Cell Chemotaxis Response to Staphylococcus Enterotoxin B Mediated Human Endothelial Cell Damage In Vitro. Scand J Immunol 2012; 75:147-56. [DOI: 10.1111/j.1365-3083.2011.02638.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Kearney DE, Wang W, Redmond HP, Wang JH. Bacterial superantigens enhance the in vitro proinflammatory response and in vivo lethality of the TLR2 agonist bacterial lipoprotein. THE JOURNAL OF IMMUNOLOGY 2011; 187:5363-9. [PMID: 22003201 DOI: 10.4049/jimmunol.1003747] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Bacterial superantigens are Gram-positive exotoxins that induce proinflammatory cytokine release in vitro, cause lethal shock in vivo, and can be detected in the bloodstream of critically ill patients. They also have a powerful priming effect on the TLR4 agonist LPS. The aim of this study was to investigate the relationship between superantigens and the TLR2 agonist bacterial lipoprotein (BLP). Priming of human monocytes or PBMCs with superantigens significantly enhanced proinflammatory cytokine TNF-α and IL-6 release in response to BLP stimulation. The priming effect of superantigens could be blocked by inhibiting p38 MAPK during the priming phase as opposed to NF-κB or ERK inhibition. This was consistent with higher expression of the phosphorylated p38 after superantigen priming and BLP or LPS stimulation. C57BL/6 mice with superantigen priming (10 μg/mouse) when challenged with BLP (600 μg/mouse) exhibited substantially higher mortality (100%) compared with mice without superantigen priming (zero). Mice given superantigen alone did not demonstrate any signs of illness. Mice challenged with both superantigen and BLP had significantly higher levels of serum TNF-α and IL-6 compared with those of mice challenged with either agent alone. Depletion of the monocyte/macrophage subpopulation significantly reduced the mortality rate from 100 to 20% in superantigen-primed, BLP-challenged C57BL/6 mice, with a 5- to 10-fold decrease in serum TNF-α and IL-6. Our results demonstrate that bacterial superantigens enhance the in vitro proinflammatory cytokine release and in vivo lethality of BLP. This novel finding may help to explain the massive proinflammatory cytokine release seen in superantigen-mediated septic shock.
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Affiliation(s)
- David E Kearney
- Department of Academic Surgery, University College Cork/National University of Ireland, Cork University Hospital, Cork, Ireland
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17
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Cook E, Wang X, Robiou N, Fries BC. Measurement of staphylococcal enterotoxin B in serum and culture supernatant with a capture enzyme-linked immunosorbent assay. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:1094-101. [PMID: 17634506 PMCID: PMC2043325 DOI: 10.1128/cvi.00183-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Staphylococcal enterotoxin B (SEB) is a select agent because it is a potent mitogen that elicits life-threatening polyclonal T-cell proliferation and cytokine production at very low concentrations. Efforts are in progress to develop therapeutic reagents and vaccines that neutralize or prevent the devastating effects of this toxin. Because of its rapid binding to in vivo receptors, this toxin is difficult to detect in serum. This rapid binding also constitutes a major challenge for the development of effective therapeutic reagents that can neutralize the effects of the toxin in vivo. We have developed a highly sensitive capture enzyme-linked immunosorbent assay that detects SEB in body fluids at very low levels. With this assay, the peak levels of SEB in serum and renal clearance can be measured in mice. After either oral ingestion or nasal inhalation of SEB by mice, this assay documents the transcytosis of SEB across the mucosal membranes into serum within 2 h. Furthermore, this assay was used to compare the SEB levels in different murine models for SEB-induced lethal shock and demonstrated that the coadministration of toxin-enhancing chemicals, such as D-galactosamine and lipopolysaccharide, can alter the peak serum SEB levels. Hence, this assay is a potentially useful tool for the study of the pharmacokinetics of SEB and the effects of potential therapeutic reagents on serum SEB levels.
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Affiliation(s)
- E Cook
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park, Bronx, NY 10461, USA
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Miwa K, Fukuyama M, Matsuno N, Shimada K, Ikeda K, Ikeda T. Physiological Response to Superantigen-Adsorbing Hemoperfusion in Toxin-Concentration-Controlled Septic Swine. Blood Purif 2006; 24:319-26. [PMID: 16534194 DOI: 10.1159/000091851] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Accepted: 09/08/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Superantigens are suspected of being potent initiators of gram-positive sepsis, and new therapies for superantigen elimination are required. The effects of hemoadsorption with a superantigen-adsorbing device (SAAD) were evaluated in septic swine. METHODS Toxic shock syndrome toxin-1 (TSST-1) was infused, and blood concentration was maintained at the clinical level for 6 h. Endotoxin was then infused to induce lethal shock. All animals were hemoperfused with SAAD or a control column for 8 h and changes in pathological parameters and mortality were examined. RESULTS Animals perfused with SAAD had a highly significant (p < 0.01) survival advantage compared with control groups at 24 h after initiation of the TSST-1 infusion. SAAD also suppressed the increase in the arteriovenous shunt ratio and decrease of partial arterial oxygen pressure at 6 h after TSST-1 infusion initiation. CONCLUSION We suggest that there is a potential application of SAAD in treating superantigen-induced respiratory dysfunction and sepsis.
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Affiliation(s)
- Keishi Miwa
- New Frontiers Research Laboratories, Toray Industries, Inc., Kanagawa, Japan.
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19
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Faulkner L, Cooper A, Fantino C, Altmann DM, Sriskandan S. The mechanism of superantigen-mediated toxic shock: not a simple Th1 cytokine storm. THE JOURNAL OF IMMUNOLOGY 2006; 175:6870-7. [PMID: 16272345 DOI: 10.4049/jimmunol.175.10.6870] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The profound clinical consequences of Gram-positive toxic shock are hypothesized to stem from excessive Th1 responses to superantigens. We used a new superantigen-sensitive transgenic model to explore the role of TCRalphabeta T cells in responses to staphylococcal enterotoxin B (SEB) in vitro and in two different in vivo models. The proliferative and cytokine responses of HLA-DR1 spleen cells were 100-fold more sensitive than controls and were entirely dependent on TCRalphabeta T cells. HLA-DR1 mice showed greater sensitivity in vivo to two doses of SEB with higher mortality and serum cytokines than controls. When d-galactosamine was used as a sensitizing agent with a single dose of SEB, HLA-DR1 mice died of toxic shock whereas controls did not. In this sensitized model of toxic shock there was a biphasic release of cytokines, including TNF-alpha, at 2 h and before death at 7 h. In both models, mortality and cytokine release at both time points were dependent on TCRalphabeta T cells. Anti-TNF-alpha pretreatment was protective against shock whereas anti-IFN gamma pretreatment and delayed anti-TNF-alpha treatment were not. Importantly, anti-TNF-alpha pretreatment inhibited the early TNF-alpha response but did not inhibit the later TNF-alpha burst, to which mortality has previously been attributed. Splenic T cells were shown definitively to be the major source of TNF-alpha during the acute cytokine response. Our results demonstrate unequivocally that TCRalphabeta T cells are critical for lethality in toxic shock but it is the early TNF-alpha response and not the later cytokine surge that mediates lethal shock.
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MESH Headings
- Animals
- Cytokines/biosynthesis
- Enterotoxins/toxicity
- Galactosamine/toxicity
- HLA-DR1 Antigen/genetics
- HLA-DR1 Antigen/metabolism
- Humans
- Mice
- Mice, Knockout
- Mice, Transgenic
- Receptors, Antigen, T-Cell, alpha-beta/deficiency
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Shock, Septic/etiology
- Shock, Septic/immunology
- Spleen/drug effects
- Spleen/immunology
- Superantigens/toxicity
- Th1 Cells/drug effects
- Th1 Cells/immunology
- Tumor Necrosis Factor-alpha/biosynthesis
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Affiliation(s)
- Lee Faulkner
- Department of Infectious Diseases, Imperial College London, London, United Kingdom
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Hopkins PA, Fraser JD, Pridmore AC, Russell HH, Read RC, Sriskandan S. Superantigen recognition by HLA class II on monocytes up-regulates toll-like receptor 4 and enhances proinflammatory responses to endotoxin. Blood 2005; 105:3655-62. [PMID: 15644417 DOI: 10.1182/blood-2004-07-2523] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
AbstractThe devastating systemic effects of bacterial superantigens may be explained by powerful proinflammatory synergy with lipopolysaccharide (LPS). However, the mechanism underlying this phenomenon remains unclear and has never been investigated in humans. Specifically, there is no known link between superantigen-induced immune effects and the pattern recognition of LPS at toll-like receptor 4 (TLR4). Here we show that bacterial superantigens induce rapid transcription and increased membrane expression of TLR4 in primary human monocytes by ligation of major histocompatibility complex (MHC) class II. We also demonstrate that superantigens are solely responsible for monocyte TLR4 up-regulation induced by products from Gram-positive bacteria. In parallel with enhanced TLR4 expression, priming of purified monocytes or mixed peripheral blood mononuclear cells with superantigens significantly enhanced the induction of proinflammatory cytokines by known TLR4 ligands. Staphylococcal enterotoxin A constructs containing targeted mutations were used to demonstrate a requirement for MHC class II ligation in both TLR4 up-regulation and enhanced responses to endotoxin. In contrast to results from animal models, superantigen-endotoxin interaction was not dependent on T-cell receptor ligation by superantigen or interferon gamma production. Pattern recognition of bacterial superantigens by MHC class II receptors may exacerbate the proinflammatory response of monocytes to Gram-negative infection or endotoxin by up-regulation of TLR4.
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Affiliation(s)
- Philip A Hopkins
- Department of Infectious Diseases, Imperial College, Du Cane Rd, London, UK
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