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Greenlee-Wacker MC, Rigby KM, Kobayashi SD, Porter AR, DeLeo FR, Nauseef WM. Phagocytosis of Staphylococcus aureus by human neutrophils prevents macrophage efferocytosis and induces programmed necrosis. THE JOURNAL OF IMMUNOLOGY 2014; 192:4709-17. [PMID: 24729616 DOI: 10.4049/jimmunol.1302692] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) pose a significant threat to human health. Polymorphonuclear leukocytes (PMN) are the first responders during staphylococcal infection, but 15-50% of the initial ingested inoculum survives within the PMN phagosome and likely contributes directly or indirectly to disease pathogenesis. We hypothesize that surviving intracellular CA-MRSA undermine effective phagocyte-mediated defense by causing a decrease in macrophage uptake of PMN containing viable S. aureus and by promoting PMN lysis. In support of this hypothesis, PMN harboring viable CA-MRSA strain USA300 (PMN-SA) upregulated the "don't eat me" signal CD47, remained bound to the surface, and were inefficiently ingested by macrophages. In addition, coculture with PMN-SA altered the macrophage phenotype. Compared to macrophages fed USA300 alone, macrophages challenged with PMN-SA produced more IL-8 and less IL-1 receptor antagonist, TNF-α, activated caspase-1, and IL-1β. Although they exhibited some features of apoptosis within 3 h following ingestion of S. aureus, including phosphatidylserine exposure and mitochondrial membrane depolarization, PMN-SA had sustained levels of proliferating cell nuclear Ag expression, absence of caspase activation, and underwent lysis within 6 h following phagocytosis. PMN lysis was dependent on receptor-interacting protein 1, suggesting that PMN-SA underwent programmed necrosis or necroptosis. These data are the first demonstration, to our knowledge, that bacteria can promote sustained expression of proliferating cell nuclear Ag and that human PMN undergo necroptosis. Together, these findings demonstrate that S. aureus surviving within PMN undermine the innate immune response and may provide insight into the pathogenesis of S. aureus disease.
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Affiliation(s)
- Mallary C Greenlee-Wacker
- Inflammation Program, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Veterans Administration Medical Center, Iowa City, IA 52240
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152
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Phosphatidylinositol-specific phospholipase C contributes to survival of Staphylococcus aureus USA300 in human blood and neutrophils. Infect Immun 2014; 82:1559-71. [PMID: 24452683 DOI: 10.1128/iai.01168-13] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Staphylococcus aureus is an important human pathogen that employs a large repertoire of secreted virulence factors to promote disease pathogenesis. Many strains of S. aureus possess a plc gene that encodes a phosphatidylinositol (PI)-specific phospholipase C (PI-PLC) capable of hydrolyzing PI and cleaving glycosyl-PI (GPI)-linked proteins from cell surfaces. Despite being secreted by virulent staphylococci, the contribution of PI-PLC to the capacity of S. aureus to cause disease remains undefined. Our goal in these studies was to understand PI-PLC in the context of S. aureus biology. Among a collection of genetically diverse clinical isolates of S. aureus, community-associated methicillin-resistant S. aureus (CA-MRSA) USA300 secreted the most PI-PLC. Screening a collection of two-component system (TCS) mutants of S. aureus, we identified both the agr quorum-sensing system and the SrrAB TCS to be positive regulators of plc gene expression. Real-time PCR and PI-PLC enzyme assays of the TCS mutants, coupled with SrrA promoter binding studies, demonstrated that SrrAB was the predominant transcriptional activator of plc. Furthermore, plc regulation was linked to oxidative stress both in vitro and in vivo in a SrrAB-dependent manner. A Δplc mutant in a CA-MRSA USA300 background exhibited a survival defect in human whole blood and in isolated neutrophils. However, the same mutant strain displayed no survival defect in murine models of infection or murine whole blood. Overall, these data identify potential links between bacterial responses to the host innate immune system and to oxidative stress and suggest how PI-PLC could contribute to the pathogenesis of S. aureus infections.
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153
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Cheung GYC, Joo HS, Chatterjee SS, Otto M. Phenol-soluble modulins--critical determinants of staphylococcal virulence. FEMS Microbiol Rev 2014; 38:698-719. [PMID: 24372362 DOI: 10.1111/1574-6976.12057] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 12/05/2013] [Accepted: 12/19/2013] [Indexed: 10/25/2022] Open
Abstract
Phenol-soluble modulins (PSMs) are a recently discovered family of amphipathic, alpha-helical peptides that have multiple roles in staphylococcal pathogenesis and contribute to a large extent to the pathogenic success of virulent staphylococci, such as Staphylococcus aureus. PSMs may cause lysis of many human cell types including leukocytes and erythrocytes, stimulate inflammatory responses, and contribute to biofilm development. PSMs appear to have an original role in the commensal lifestyle of staphylococci, where they facilitate growth and spreading on epithelial surfaces. Aggressive, cytolytic PSMs seem to have evolved from that original role and are mainly expressed in highly virulent S. aureus. Here, we will review the biochemistry, genetics, and role of PSMs in the commensal and pathogenic lifestyles of staphylococci, discuss how diversification of PSMs defines the aggressiveness of staphylococcal species, and evaluate potential avenues to target PSMs for drug development against staphylococcal infections.
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Affiliation(s)
- Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD, USA
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154
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Walker JN, Crosby HA, Spaulding AR, Salgado-Pabón W, Malone CL, Rosenthal CB, Schlievert PM, Boyd JM, Horswill AR. The Staphylococcus aureus ArlRS two-component system is a novel regulator of agglutination and pathogenesis. PLoS Pathog 2013; 9:e1003819. [PMID: 24367264 PMCID: PMC3868527 DOI: 10.1371/journal.ppat.1003819] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 10/21/2013] [Indexed: 01/31/2023] Open
Abstract
Staphylococcus aureus is a prominent bacterial pathogen that is known to agglutinate in the presence of human plasma to form stable clumps. There is increasing evidence that agglutination aids S. aureus pathogenesis, but the mechanisms of this process remain to be fully elucidated. To better define this process, we developed both tube based and flow cytometry methods to monitor clumping in the presence of extracellular matrix proteins. We discovered that the ArlRS two-component system regulates the agglutination mechanism during exposure to human plasma or fibrinogen. Using divergent S. aureus strains, we demonstrated that arlRS mutants are unable to agglutinate, and this phenotype can be complemented. We found that the ebh gene, encoding the Giant Staphylococcal Surface Protein (GSSP), was up-regulated in an arlRS mutant. By introducing an ebh complete deletion into an arlRS mutant, agglutination was restored. To assess whether GSSP is the primary effector, a constitutive promoter was inserted upstream of the ebh gene on the chromosome in a wildtype strain, which prevented clump formation and demonstrated that GSSP has a negative impact on the agglutination mechanism. Due to the parallels of agglutination with infective endocarditis development, we assessed the phenotype of an arlRS mutant in a rabbit combined model of sepsis and endocarditis. In this model the arlRS mutant displayed a large defect in vegetation formation and pathogenesis, and this phenotype was partially restored by removing GSSP. Altogether, we have discovered that the ArlRS system controls a novel mechanism through which S. aureus regulates agglutination and pathogenesis. Staphylococcus aureus is a bacterial pathogen that is responsible for causing significant disease in humans. The development of antibiotic resistant strains has made these infections more difficult to treat, and an improved understanding of how this pathogen causes infections will facilitate the development of new tools for treatment. It has long been recognized that S. aureus can bind human matrix proteins to form stable clumps in a process called agglutination, but the importance of agglutination during infection is only just becoming understood. In this work, we developed several techniques to investigate the S. aureus agglutination mechanism. We discovered that the ArlRS two-component regulatory system controls agglutination by regulating the expression of the ebh gene, which encodes the Giant Staphylococcal Surface Protein (GSSP). When ArlRS is non-functional, S. aureus agglutination is prevented through the action of GSSP. These phenotypes were confirmed in a rabbit model of sepsis and infective endocarditis, demonstrating that ArlRS is an important regulator of virulence. Taken together, the identification of ArlRS as a regulator of S. aureus agglutination and pathogenesis may lead to innovative directions for therapeutic development.
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Affiliation(s)
- Jennifer N Walker
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Heidi A Crosby
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Adam R Spaulding
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Wilmara Salgado-Pabón
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Cheryl L Malone
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Carolyn B Rosenthal
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Patrick M Schlievert
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
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155
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Ko YP, Kuipers A, Freitag CM, Jongerius I, Medina E, van Rooijen WJ, Spaan AN, van Kessel KPM, Höök M, Rooijakkers SHM. Phagocytosis escape by a Staphylococcus aureus protein that connects complement and coagulation proteins at the bacterial surface. PLoS Pathog 2013; 9:e1003816. [PMID: 24348255 PMCID: PMC3861539 DOI: 10.1371/journal.ppat.1003816] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 10/21/2013] [Indexed: 01/01/2023] Open
Abstract
Upon contact with human plasma, bacteria are rapidly recognized by the complement system that labels their surface for uptake and clearance by phagocytic cells. Staphylococcus aureus secretes the 16 kD Extracellular fibrinogen binding protein (Efb) that binds two different plasma proteins using separate domains: the Efb N-terminus binds to fibrinogen, while the C-terminus binds complement C3. In this study, we show that Efb blocks phagocytosis of S. aureus by human neutrophils. In vitro, we demonstrate that Efb blocks phagocytosis in plasma and in human whole blood. Using a mouse peritonitis model we show that Efb effectively blocks phagocytosis in vivo, either as a purified protein or when produced endogenously by S. aureus. Mutational analysis revealed that Efb requires both its fibrinogen and complement binding residues for phagocytic escape. Using confocal and transmission electron microscopy we show that Efb attracts fibrinogen to the surface of complement-labeled S. aureus generating a ‘capsule’-like shield. This thick layer of fibrinogen shields both surface-bound C3b and antibodies from recognition by phagocytic receptors. This information is critical for future vaccination attempts, since opsonizing antibodies may not function in the presence of Efb. Altogether we discover that Efb from S. aureus uniquely escapes phagocytosis by forming a bridge between a complement and coagulation protein. Staphylococcus aureus is a leading cause of severe bacterial infections in both hospital and community settings. Due to its increasing resistance to antibiotics, development of additional therapeutic strategies like vaccination is required to control this pathogen. Vaccination attempts against S. aureus have not been successful so far and an important reason may be the pathogen's elaborate repertoire of molecules that dampen the immune response. These evasion molecules not only suppress natural immunity but also hamper the current attempts to create effective vaccines. In this paper, we describe a novel mechanism by which S. aureus can prevent uptake by phagocytic immune cells. We discover that the secreted S. aureus protein Extracellular fibrinogen binding protein (Efb) generates a ‘capsule’-like shield around the bacterial surface through a dual interaction with the plasma proteins complement C3b and fibrinogen. The Efb-dependent fibrinogen shield masks important opsonic molecules like C3b and antibodies from binding to phagocyte receptors. This information is critical for future vaccination attempts, since opsonizing antibodies may not function in the presence of this anti-phagocytic shield.
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Affiliation(s)
- Ya-Ping Ko
- Center for Infectious and Inflammatory Disease, Institute of Bioscience and Technology, Texas A&M University Health Science Center, Houston, Texas, United States of America
| | - Annemarie Kuipers
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Claudia M. Freitag
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
- Utrecht University, Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht, The Netherlands
| | - Ilse Jongerius
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Eva Medina
- Infection Immunology Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | - András N. Spaan
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kok P. M. van Kessel
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Magnus Höök
- Center for Infectious and Inflammatory Disease, Institute of Bioscience and Technology, Texas A&M University Health Science Center, Houston, Texas, United States of America
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156
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Pang YY, Schwartz J, Bloomberg S, Boyd JM, Horswill AR, Nauseef WM. Methionine sulfoxide reductases protect against oxidative stress in Staphylococcus aureus encountering exogenous oxidants and human neutrophils. J Innate Immun 2013; 6:353-64. [PMID: 24247266 DOI: 10.1159/000355915] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 09/17/2013] [Indexed: 11/19/2022] Open
Abstract
To establish infection successfully, Staphylococcus aureus must evade clearance by polymorphonuclear neutrophils (PMN). We studied the expression and regulation of the methionine sulfoxide reductases (Msr) that are involved in the repair of oxidized staphylococcal proteins and investigated their influence on the fate of S. aureus exposed to oxidants or PMN. We evaluated a mutant deficient in msrA1 and msrB for susceptibility to hydrogen peroxide, hypochlorous acid and PMN. The expression of msrA1 in wild-type bacteria ingested by human PMN was assessed by real-time PCR. The regulation of msr was studied by screening a library of two-component regulatory system (TCS) mutants for altered msr responses. Relative to the wild-type bacteria, bacteria deficient in Msr were more susceptible to oxidants and PMN. Upregulation of staphylococcal msrA1 occurred within the phagosomes of normal PMN and PMN deficient in NADPH oxidase activity. Furthermore, PMN granule-rich extract stimulated the upregulation of msrA1. Modulation of msrA1 within PMN was shown to be partly dependent on the VraSR TCS. Msr contributes to staphylococcal responses to oxidative attack and PMN. Our study highlights a novel interaction between the oxidative protein repair pathway and the VraSR TCS that is involved in cell wall homeostasis.
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Affiliation(s)
- Yun Yun Pang
- Inflammation Program, Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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157
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Global transcriptome analysis of Staphylococcus aureus biofilms in response to innate immune cells. Infect Immun 2013; 81:4363-76. [PMID: 24042108 DOI: 10.1128/iai.00819-13] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The potent phagocytic and microbicidal activities of neutrophils and macrophages are among the first lines of defense against bacterial infections. Yet Staphylococcus aureus is often resistant to innate immune defense mechanisms, especially when organized as a biofilm. To investigate how S. aureus biofilms respond to macrophages and neutrophils, gene expression patterns were profiled using Affymetrix microarrays. The addition of macrophages to S. aureus static biofilms led to a global suppression of the biofilm transcriptome with a wide variety of genes downregulated. Notably, genes involved in metabolism, cell wall synthesis/structure, and transcription/translation/replication were among the most highly downregulated, which was most dramatic at 1 h compared to 24 h following macrophage addition to biofilms. Unexpectedly, few genes were enhanced in biofilms after macrophage challenge. Unlike coculture with macrophages, coculture of S. aureus static biofilms with neutrophils did not greatly influence the biofilm transcriptome. Collectively, these experiments demonstrate that S. aureus biofilms differentially modify their gene expression patterns depending on the leukocyte subset encountered.
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158
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Chiu IM, Heesters BA, Ghasemlou N, Von Hehn CA, Zhao F, Tran J, Wainger B, Strominger A, Muralidharan S, Horswill AR, Wardenburg JB, Hwang SW, Carroll MC, Woolf CJ. Bacteria activate sensory neurons that modulate pain and inflammation. Nature 2013; 501:52-7. [PMID: 23965627 PMCID: PMC3773968 DOI: 10.1038/nature12479] [Citation(s) in RCA: 620] [Impact Index Per Article: 56.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 07/17/2013] [Indexed: 12/12/2022]
Abstract
Nociceptor sensory neurons are specialized to detect potentially damaging stimuli, protecting the organism by initiating the sensation of pain and eliciting defensive behaviours. Bacterial infections produce pain by unknown molecular mechanisms, although they are presumed to be secondary to immune activation. Here we demonstrate that bacteria directly activate nociceptors, and that the immune response mediated through TLR2, MyD88, T cells, B cells, and neutrophils and monocytes is not necessary for Staphylococcus aureus-induced pain in mice. Mechanical and thermal hyperalgesia in mice is correlated with live bacterial load rather than tissue swelling or immune activation. Bacteria induce calcium flux and action potentials in nociceptor neurons, in part via bacterial N-formylated peptides and the pore-forming toxin α-haemolysin, through distinct mechanisms. Specific ablation of Nav1.8-lineage neurons, which include nociceptors, abrogated pain during bacterial infection, but concurrently increased local immune infiltration and lymphadenopathy of the draining lymph node. Thus, bacterial pathogens produce pain by directly activating sensory neurons that modulate inflammation, an unsuspected role for the nervous system in host-pathogen interactions.
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Affiliation(s)
- Isaac M. Chiu
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Balthasar A. Heesters
- Boston Children's Hospital, Program in Cellular and Molecular Medicine, and Harvard Medical School, Boston, Massachusetts 02115, USA
- Medical Microbiology, University Medical Center, Utrecht, Utrecht, The Netherlands
| | - Nader Ghasemlou
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Christian A. Von Hehn
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Fan Zhao
- Department of Chemistry, Quantitative Biology Program, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Johnathan Tran
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Brian Wainger
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Amanda Strominger
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Sriya Muralidharan
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Alexander R. Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | | | - Sun Wook Hwang
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Korea University Graduate School of Medicine, Seoul 136-705, Korea
| | - Michael C. Carroll
- Boston Children's Hospital, Program in Cellular and Molecular Medicine, and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Clifford J. Woolf
- Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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159
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Surewaard BGJ, de Haas CJC, Vervoort F, Rigby KM, DeLeo FR, Otto M, van Strijp JAG, Nijland R. Staphylococcal alpha-phenol soluble modulins contribute to neutrophil lysis after phagocytosis. Cell Microbiol 2013; 15:1427-37. [PMID: 23470014 PMCID: PMC4784422 DOI: 10.1111/cmi.12130] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 02/07/2013] [Accepted: 02/20/2013] [Indexed: 01/01/2023]
Abstract
Staphylococcus aureus community-acquired (CA) MRSA strains are highly virulent and can cause infections in otherwise healthy individuals. The most important mechanism of the host for clearing S. aureus is phagocytosis by neutrophils and subsequent killing of the pathogen. Especially CA-MRSA strains are very efficient in circumventing this neutrophil killing. Interestingly, only a relative small number of virulence factors have been associated with CA-MRSA, one of which are the phenol soluble modulins (PSMs). We have recently shown that the PSMs are functionally inhibited by serum lipoproteins, indicating that PSMs may exert their cytolytic function primarily in the intracellular environment. To further investigate the intracellular role of the PSMs we measured the effect of the α-type and β-type PSMs on neutrophil killing after phagocytosis. Using fluorescently labelled S. aureus, we measured bacterial survival after phagocytosis in a plate reader, which was employed next to flow cytometry and time-lapse microscopy. Phagocytosis of the CA-MRSA strain MW2 by human neutrophils resulted in rapid host cell death. Using mutant strains of MW2, we demonstrated that in the presence of serum, the intracellular expression of only the psmα operon is both necessary and sufficient for both increased neutrophil cell death and increased survival of S. aureus. Our results identify PSMα peptides as prominent contributors to killing of neutrophils after phagocytosis, a finding with major implications for our understanding of S. aureus pathogenesis and strategies for S. aureus vaccine development.
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Affiliation(s)
- BGJ Surewaard
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - CJC de Haas
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - F Vervoort
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - KM Rigby
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, Montana, USA
| | - FR DeLeo
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, Montana, USA
| | - M Otto
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases (NIAID), The National Institutes of Health (NIH), Bethesda, MD, USA
| | - JAG van Strijp
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - R Nijland
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
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160
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Zurek OW, Nygaard TK, Watkins RL, Pallister KB, Torres VJ, Horswill AR, Voyich JM. The role of innate immunity in promoting SaeR/S-mediated virulence in Staphylococcus aureus. J Innate Immun 2013; 6:21-30. [PMID: 23816635 DOI: 10.1159/000351200] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 04/05/2013] [Indexed: 11/19/2022] Open
Abstract
The ability of Staphylococcus aureus to infect tissues is dependent on precise control of virulence through gene-regulatory systems. While the SaeR/S two-component system has been shown to be a major regulator of S. aureus virulence, the influence of the host environment on SaeR/S-regulated genes (saeR/S targets) remains incompletely defined. Using QuantiGene 2.0 transcriptional assays, we examined expression of genes with the SaeR binding site in USA300 exposed to human and mouse neutrophils and host-derived peptides and during subcutaneous skin infection. We found that only some of the saeR/S targets, as opposed to the entire SaeR/S virulon, were activated within 5 and 10 min of interacting with human neutrophils as well as α-defensin. Furthermore, mouse neutrophils promoted transcription of saeR/S targets despite lacking α-defensin, and the murine skin environment elicited a distinctive expression profile of saeR/S targets. These findings indicate that saeR/S-mediated transcription is unique to and dependent on specific host stimuli. By using isogenic USA300ΔsaeR/S and USA300Δagr knockout strains, we also determined that SaeR/S is the major regulator of virulence factors, while Agr, a quorum-sensing two-component system, has moderate influence on transcription of the saeR/S targets under the tested physiological conditions.
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Affiliation(s)
- Oliwia W Zurek
- Department of Immunology and Infectious Diseases, Montana State University, Bozeman, Mont., USA
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161
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Abstract
Staphylococcus aureus is a known cause of chronic biofilm infections that can reside on medical implants or host tissue. Recent studies have demonstrated an important role for proteinaceous material in the biofilm structure. The S. aureus genome encodes many secreted proteases, and there is growing evidence that these enzymes have self-cleavage properties that alter biofilm integrity. However, the specific contribution of each protease and mechanism of biofilm modulation is not clear. To address this issue, we utilized a sigma factor B (ΔsigB) mutant where protease activity results in a biofilm-negative phenotype, thereby creating a condition where the protease(s) responsible for the phenotype could be identified. Using a plasma-coated microtiter assay, biofilm formation was restored to the ΔsigB mutant through the addition of the cysteine protease inhibitor E-64 or by using Staphostatin inhibitors that specifically target the extracellular cysteine proteases SspB and ScpA (called Staphopains). Through construction of gene deletion mutants, we determined that an sspB scpA double mutant restored ΔsigB biofilm formation, and this recovery could be replicated in plasma-coated flow cell biofilms. Staphopain levels were also found to be decreased under biofilm-forming conditions, possibly allowing biofilm establishment. The treatment of S. aureus biofilms with purified SspB or ScpA enzyme inhibited their formation, and ScpA was also able to disperse an established biofilm. The antibiofilm properties of ScpA were conserved across S. aureus strain lineages. These findings suggest an underappreciated role of the SspB and ScpA cysteine proteases in modulating S. aureus biofilm architecture.
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162
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Wong CHY, Jenne CN, Petri B, Chrobok NL, Kubes P. Nucleation of platelets with blood-borne pathogens on Kupffer cells precedes other innate immunity and contributes to bacterial clearance. Nat Immunol 2013; 14:785-92. [PMID: 23770641 PMCID: PMC4972575 DOI: 10.1038/ni.2631] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 04/25/2013] [Indexed: 12/13/2022]
Abstract
Using intravital imaging of the liver, we unveil a collaborative role for platelets with Kupffer cells (KCs) in eradicating bloodborne bacterial infections. Under basal conditions, platelets via glycoprotein Ib (GPIb) formed transient “touch-and-go” interactions with von Willebrand factor (vWF) constitutively expressed on KCs. Bacteria, such as Bacillus cereus and Methicillin-resistant Staphylococcus aureus (MRSA), were rapidly caught by KCs and triggered platelets to switch from “touch-and-go” to sustained GPIIb-mediated adhesion on the KC surface to encase the bacterium. Infected GpIbα−/− mice demonstrated increased endothelial and KC damage, leading to increased fluid leakage, significant polycythemia and rapid mortality. This study identifies a novel surveillance mechanism of intravascular macrophage by platelets that rapidly converts to a critical host response against bloodborne bacteria.
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Affiliation(s)
- Connie H Y Wong
- Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Alberta, Canada
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163
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Soromou LW, Zhang Y, Cui Y, Wei M, Chen N, Yang X, Huo M, Baldé A, Guan S, Deng X, Wang D. Subinhibitory concentrations of pinocembrin exert anti-Staphylococcus aureus activity by reducing α-toxin expression. J Appl Microbiol 2013; 115:41-9. [PMID: 23594163 DOI: 10.1111/jam.12221] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/13/2013] [Accepted: 03/20/2013] [Indexed: 11/29/2022]
Abstract
AIMS Natural products have been used as potentially important sources of novel antibacterials in combating pathogenic Staphylococcus aureus isolates, a major problem around the world. In this study, we aimed to investigate the antibacterial effects of pinocembrin (PNCB) against Staph. aureus pneumonia in a murine model and its influence on the production of Staph. aureus α-haemolysin (Hla). METHODS AND RESULTS The in vitro activities of PNCB on α-haemolysin production were determined using haemolysis, Western blot and real-time RT-PCR assays. The viability and cytotoxicity assays were performed to evaluate the influence of PNCB on α-toxin-mediated injury of human alveolar epithelial cells. Moreover, through histopathologic analysis, we further determined the in vivo effects of PNCB on Staph. aureus pneumonia in a mouse model. In vitro, PNCB at low concentrations exhibited inhibitory activity against α-haemolysin production and attenuated α-haemolysin-mediated cell injury. Furthermore, the in vivo findings demonstrated that PNCB protected mice from Staph. aureus pneumonia. CONCLUSIONS We have provided new evidence of the effects of PNCB, which suggest that PNCB attenuated α-haemolysin-mediated cell injury and protected mice from Staph. aureus pneumonia. SIGNIFICANCE AND IMPACT OF THE STUDY The findings indicate that PNCB may be used as a basis for anti-Staphylococcus agent.
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Affiliation(s)
- L W Soromou
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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164
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The activity of σV, an extracytoplasmic function σ factor of Bacillus subtilis, is controlled by regulated proteolysis of the anti-σ factor RsiV. J Bacteriol 2013; 195:3135-44. [PMID: 23687273 DOI: 10.1128/jb.00292-13] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
During growth in the environment, bacteria encounter stresses which can delay or inhibit their growth. To defend against these stresses, bacteria induce both resistance and repair mechanisms. Many bacteria regulate these resistance mechanisms using a group of alternative σ factors called extracytoplasmic function (ECF) σ factors. ECF σ factors represent the largest and most diverse family of σ factors. Here, we demonstrate that the activation of a member of the ECF30 subfamily of ECF σ factors, σ(V) in Bacillus subtilis, is controlled by the proteolytic destruction of the anti-σ factor RsiV. We will demonstrate that the degradation of RsiV and, thus, the activation of σ(V) requires multiple proteolytic steps. Upon exposure to the inducer lysozyme, the extracellular domain of RsiV is removed by an unknown protease, which cleaves at site 1. This cleavage is independent of PrsW, the B. subtilis site 1 protease, which cleaves the anti-σ factor RsiW. Following cleavage by the unknown protease, the N-terminal portion of RsiV requires further processing, which requires the site 2 intramembrane protease RasP. Our data indicate that the N-terminal portion of RsiV from amino acid 1 to 60, which lacks the extracellular domain, is constitutively degraded unless RasP is absent, indicating that RasP cleavage is constitutive. This suggests that the regulatory step in RsiV degradation and, thus, σ(V) activation are controlled at the level of the site 1 cleavage. Finally, we provide evidence that increased resistance to lysozyme decreases σ(V) activation. Collectively, these data provide evidence that the mechanism for σ(V) activation in B. subtilis is controlled by regulated intramembrane proteolysis (RIP) and requires the site 2 protease RasP.
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165
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Dupré-Crochet S, Erard M, Nüβe O. ROS production in phagocytes: why, when, and where? J Leukoc Biol 2013; 94:657-70. [PMID: 23610146 DOI: 10.1189/jlb.1012544] [Citation(s) in RCA: 305] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In the phagocytosis field, ROS production by the phagocyte NOX has been associated with pathogen killing for the last 50 years. Since the discovery of nonphagocyte NOX, numerous other roles for ROS production have been identified. Oxidative stress and ROS-mediated signaling have received much attention in recent years. Much lower concentrations of ROS may be required for signaling compared with microbial killing. Based on the discoveries in nonphagocytic cells, it became logical to look for ROS functions distinct from pathogen killing, even in phagocytes. ROS are now linked to various forms of cell death, to chemotaxis, and to numerous modifications of cellular processes, including the NOX itself. ROS functions are clearly concentration-dependent over a wide range of concentrations. How much is required for which function? Which species are required for how much time? Is ROS signaling only a side effect of bactericidal ROS production? One major obstacle to answer these questions is the difficulty of reliable quantitative ROS detection. Signal transduction often takes place on a subcellular scale over periods of seconds or minutes, so the detection methods need to provide appropriate time and space resolution. We present examples of local ROS production, decreased degradation, signaling events, and potentially ROS-sensitive functions. We attempt to illustrate the current limitations for quantitative spatiotemporal ROS detection and point out directions for ongoing development. Probes for localized ROS detection and for combined detection of ROS, together with protein localization or other cellular parameters, are constantly improved.
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166
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Quantitative analysis of autoinducing peptide I (AIP-I) from Staphylococcus aureus cultures using ultrahigh performance liquid chromatography-high resolving power mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2013; 930:7-12. [PMID: 23703543 DOI: 10.1016/j.jchromb.2013.04.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 04/04/2013] [Accepted: 04/12/2013] [Indexed: 01/09/2023]
Abstract
Staphylococcus aureus infections acquired in hospitals now cause more deaths per annum in the US than does HIV/AIDS. Perhaps even more alarming is the rise in community associated methicillin-resistant S. aureus (CA-MRSA) infections, which have spread out of hospital settings and are infecting otherwise healthy individuals. The mechanism of enhanced pathogenesis in CA-MRSA remains unclear, but it has been postulated that high activity in the agr quorum-sensing system could be a contributing factor. The purpose of this study was to develop a quantitative method for analysis of autoinducing peptide I (AIP-I), the activating signal for the agr system in S. aureus. An effective method was developed using ultrahigh performance liquid chromatography (UHPLC) coupled to electrospray ionization mass spectrometry with an LTQ Orbitrap mass spectrometer. Relying on the exceptional resolving power and mass accuracy of this instrument configuration, it was possible to quantify AIP-I directly from the complex growth media of S. aureus cultures with a limit of detection (LOD) of 0.25μM and a linear dynamic range of 2.6 to 63μM. The method was then employed to monitor time-dependent production of AIP-I by S. aureus cultures, and it was observed that AIP-I production reached a maximum and leveled off after approximately 16h. Finally, it was determined that virulence of S. aureus was correlated with AIP-I production in some (but not all) strains analyzed.
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167
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Abstract
Several prominent bacterial pathogens secrete nuclease (Nuc) enzymes that have an important role in combating the host immune response. Early studies of Staphylococcus aureus Nuc attributed its regulation to the agr quorum-sensing system. However, recent microarray data have indicated that nuc is under the control of the SaeRS two-component system, which is a major regulator of S. aureus virulence determinants. Here we report that the nuc gene is directly controlled by the SaeRS two-component system through reporter fusion, immunoblotting, Nuc activity measurements, promoter mapping, and binding studies, and additionally, we were unable identify a notable regulatory link to the agr system. The observed SaeRS-dependent regulation was conserved across a wide spectrum of representative S. aureus isolates. Moreover, with community-associated methicillin-resistant S. aureus (CA MRSA) in a mouse model of peritonitis, we observed in vivo expression of Nuc activity in an SaeRS-dependent manner and determined that Nuc is a virulence factor that is important for in vivo survival, confirming the enzyme's role as a contributor to invasive disease. Finally, natural polymorphisms were identified in the SaeRS proteins, one of which was linked to Nuc regulation in a CA MRSA USA300 endocarditis isolate. Altogether, our findings demonstrate that Nuc is an important S. aureus virulence factor and part of the SaeRS regulon.
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168
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Hall PR, Elmore BO, Spang CH, Alexander SM, Manifold-Wheeler BC, Castleman MJ, Daly SM, Peterson MM, Sully EK, Femling JK, Otto M, Horswill AR, Timmins GS, Gresham HD. Nox2 modification of LDL is essential for optimal apolipoprotein B-mediated control of agr type III Staphylococcus aureus quorum-sensing. PLoS Pathog 2013; 9:e1003166. [PMID: 23459693 PMCID: PMC3573103 DOI: 10.1371/journal.ppat.1003166] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 12/17/2012] [Indexed: 12/29/2022] Open
Abstract
Staphylococcus aureus contains an autoinducing quorum-sensing system encoded within the agr operon that coordinates expression of virulence genes required for invasive infection. Allelic variation within agr has generated four agr specific groups, agr I-IV, each of which secretes a distinct autoinducing peptide pheromone (AIP1-4) that drives agr signaling. Because agr signaling mediates a phenotypic change in this pathogen from an adherent colonizing phenotype to one associated with considerable tissue injury and invasiveness, we postulated that a significant contribution to host defense against tissue damaging and invasive infections could be provided by innate immune mechanisms that antagonize agr signaling. We determined whether two host defense factors that inhibit AIP1-induced agrI signaling, Nox2 and apolipoprotein B (apoB), also contribute to innate control of AIP3-induced agrIII signaling. We hypothesized that apoB and Nox2 would function differently against AIP3, which differs from AIP1 in amino acid sequence and length. Here we show that unlike AIP1, AIP3 is resistant to direct oxidant inactivation by Nox2 characteristic ROS. Rather, the contribution of Nox2 to defense against agrIII signaling is through oxidation of LDL. ApoB in the context of oxLDL, and not LDL, provides optimal host defense against S. aureus agrIII infection by binding the secreted signaling peptide, AIP3, and preventing expression of the agr-driven virulence factors which mediate invasive infection. ApoB within the context of oxLDL also binds AIP 1-4 and oxLDL antagonizes agr signaling by all four agr alleles. Our results suggest that Nox2-mediated oxidation of LDL facilitates a conformational change in apoB to one sufficient for binding and sequestration of all four AIPs, demonstrating the interdependence of apoB and Nox2 in host defense against agr signaling. These data reveal a novel role for oxLDL in host defense against S. aureus quorum-sensing signaling.
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Affiliation(s)
- Pamela R Hall
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, New Mexico, USA.
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169
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Cech NB, Junio HA, Ackermann LW, Kavanaugh JS, Horswill AR. Quorum quenching and antimicrobial activity of goldenseal (Hydrastis canadensis) against methicillin-resistant Staphylococcus aureus (MRSA). PLANTA MEDICA 2012; 78:1556-61. [PMID: 22814821 PMCID: PMC4527992 DOI: 10.1055/s-0032-1315042] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The popular herbal remedy goldenseal (Hydrastis canadensis L.) is traditionally used to treat skin infections. With this study, we show activity of H. canadensis extracts in vitro against methicillin-resistant Staphylococcus aureus (MRSA). An extract from H. canadensis leaves demonstrated more potent antimicrobial activity than the alkaloid berberine alone (MICs of 75 µg/mL and 150 µg/mL, respectively). LC-MS detected alkaloids and efflux-pump inhibitory flavonoids in the extract, and the latter may explain the enhanced efficacy of the extract compared to berberine alone. We also show evidence of anti-virulence activity as a second mechanism by which H. canadensis acts against S. aureus. The H. canadensis leaf extract (but not the isolated alkaloids berberine, hydrastine, and canadine) demonstrated quorum quenching activity against several clinically relevant MRSA isolates (USA300 strains). Our data suggest that this occurs by attenuation of signal transduction through the AgrCA two-component system. Consistent with this observation, the extract inhibited toxin production by MRSA and prevented damage by MRSA to keratinocyte cells in vitro. Collectively, our results show that H. canadensis leaf extracts possess a mixture of constituents that act against MRSA via several different mechanisms. These findings lend support for the traditional application of crude H. canadensis extracts in the prevention of infection.
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Affiliation(s)
- Nadja B Cech
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, Greensboro, NC, USA.
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170
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Seidl K, Solis NV, Bayer AS, Hady WA, Ellison S, Klashman MC, Xiong YQ, Filler SG. Divergent responses of different endothelial cell types to infection with Candida albicans and Staphylococcus aureus. PLoS One 2012; 7:e39633. [PMID: 22745797 PMCID: PMC3382135 DOI: 10.1371/journal.pone.0039633] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 05/27/2012] [Indexed: 01/18/2023] Open
Abstract
Endothelial cells are important in the pathogenesis of bloodstream infections caused by Candida albicans and Staphylococcus aureus. Numerous investigations have used human umbilical vein endothelial cells (HUVECs) to study microbial-endothelial cell interactions in vitro. However, the use of HUVECs requires a constant supply of umbilical cords, and there are significant donor-to-donor variations in these endothelial cells. The use of an immortalized endothelial cell line would obviate such difficulties. One candidate in this regard is HMEC-1, an immortalized human dermal microvascular endothelial cell line. To determine if HMEC-1 cells are suitable for studying the interactions of C. albicans and S. aureus with endothelial cells in vitro, we compared the interactions of these organisms with HMEC-1 cells and HUVECs. We found that wild-type C. albicans had significantly reduced adherence to and invasion of HMEC-1 cells as compared to HUVECs. Although wild-type S. aureus adhered to and invaded HMEC-1 cells similarly to HUVECs, an agr mutant strain had significantly reduced invasion of HMEC-1 cells, but not HUVECs. Furthermore, HMEC-1 cells were less susceptible to damage induced by C. albicans, but more susceptible to damage caused by S. aureus. In addition, HMEC-1 cells secreted very little IL-8 in response to infection with either organism, whereas infection of HUVECs induced substantial IL-8 secretion. This weak IL-8 response was likely due to the anatomic site from which HMEC-1 cells were obtained because infection of primary human dermal microvascular endothelial cells with C. albicans and S. aureus also induced little increase in IL-8 production above basal levels. Thus, C. albicans and S. aureus interact with HMEC-1 cells in a substantially different manner than with HUVECs, and data obtained with one type of endothelial cell cannot necessarily be extrapolated to other types.
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Affiliation(s)
- Kati Seidl
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Norma V. Solis
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Arnold S. Bayer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Wessam Abdel Hady
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Steven Ellison
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- Department of Biology, California State University-Dominguez Hills, Carson, California, United States of America
| | - Meredith C. Klashman
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Yan Q. Xiong
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Scott G. Filler
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
- * E-mail:
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171
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Futosi K, Németh T, Pick R, Vántus T, Walzog B, Mócsai A. Dasatinib inhibits proinflammatory functions of mature human neutrophils. Blood 2012; 119:4981-91. [PMID: 22411867 PMCID: PMC3367900 DOI: 10.1182/blood-2011-07-369041] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 03/02/2012] [Indexed: 12/25/2022] Open
Abstract
Dasatinib is a tyrosine kinase inhibitor used to treat imatinib-resistant chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. At present, little is known about how dasatinib influences nonmalignant cells. In the present study, we tested the effect of dasatinib on functional responses of normal mature human neutrophils. Dasatinib completely blocked integrin- and Fc-receptor-mediated neutrophil functions, with the lowest IC(50) values below 10nM under serum-free conditions. Dasatinib caused a partial inhibition of neutrophil responses triggered by G-protein-coupled receptors and had a moderate effect on neutrophil responses triggered by microbial compounds. Whereas dasatinib inhibited neutrophil chemotaxis under static conditions in 2 dimensions, it did not affect migration under flow conditions or in 3-dimensional environments. Dasatinib did not have any major effect on phagocytosis or killing of bacteria by neutrophils. Adhesion of human neutrophils in the presence of whole serum was significantly inhibited by 50-100nM dasatinib, which corresponds to the reported serum concentrations in dasatinib-treated patients. Finally, ex vivo adhesion of mouse peripheral blood neutrophils was strongly reduced after oral administration of 5 mg/kg of dasatinib. Those results suggest that dasatinib treatment may affect the proinflammatory functions of mature neutrophils and raise the possibility that dasatinib-related compounds may provide clinical benefit in neutrophil-mediated inflammatory diseases.
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Affiliation(s)
- Krisztina Futosi
- Department of Physiology, Semmelweis University School of Medicine, Budapest, Hungary
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172
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Nygaard TK, Pallister KB, DuMont AL, DeWald M, Watkins RL, Pallister EQ, Malone C, Griffith S, Horswill AR, Torres VJ, Voyich JM. Alpha-toxin induces programmed cell death of human T cells, B cells, and monocytes during USA300 infection. PLoS One 2012; 7:e36532. [PMID: 22574180 PMCID: PMC3344897 DOI: 10.1371/journal.pone.0036532] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 04/03/2012] [Indexed: 11/19/2022] Open
Abstract
This investigation examines the influence of alpha-toxin (Hla) during USA300 infection of human leukocytes. Survival of an USA300 isogenic deletion mutant of hla (USA300Δhla) in human blood was comparable to the parental wild-type strain and polymorphonuclear leukocyte (PMN) plasma membrane permeability caused by USA300 did not require Hla. Flow cytometry analysis of peripheral blood mononuclear cells (PBMCs) following infection by USA300, USA300Δhla, and USA300Δhla transformed with a plasmid over-expressing Hla (USA300Δhla Comp) demonstrated this toxin plays a significant role inducing plasma membrane permeability of CD14+, CD3+, and CD19+ PBMCs. Rapid plasma membrane permeability independent of Hla was observed for PMNs, CD14+ and CD19+ PBMCs following intoxication with USA300 supernatant while the majority of CD3+ PBMC plasma membrane permeability induced by USA300 required Hla. Addition of recombinant Hla to USA300Δhla supernatant rescued CD3+ and CD19+ PBMC plasma membrane permeability generated by USA300 supernatant. An observed delay in plasma membrane permeability caused by Hla in conjunction with Annexin V binding and ApoBrdU Tunel assays examining PBMCs intoxicated with recombinant Hla or infected with USA300, USA300Δhla, USA300Δhla Comp, and USA300ΔsaeR/S suggest Hla induces programmed cell death of monocytes, B cells, and T cells that results in plasma membrane permeability. Together these findings underscore the importance of Hla during S. aureus infection of human tissue and specifically demonstrate Hla activity during USA300 infection triggers programmed cell death of human monocytes, T cells and B cells that leads to plasma membrane permeability.
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Affiliation(s)
- Tyler K. Nygaard
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Kyler B. Pallister
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Ashley L. DuMont
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Mark DeWald
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Robert L. Watkins
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Erik Q. Pallister
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Cheryl Malone
- Department of Microbiology University of Iowa, Iowa City, Iowa, United States of America
| | - Shannon Griffith
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Alexander R. Horswill
- Department of Microbiology University of Iowa, Iowa City, Iowa, United States of America
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Jovanka M. Voyich
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
- * E-mail:
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173
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Fraunholz M, Sinha B. Intracellular Staphylococcus aureus: live-in and let die. Front Cell Infect Microbiol 2012; 2:43. [PMID: 22919634 PMCID: PMC3417557 DOI: 10.3389/fcimb.2012.00043] [Citation(s) in RCA: 263] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 03/15/2012] [Indexed: 12/30/2022] Open
Abstract
Staphylococcus aureus uses a plethora of virulence factors to accommodate a diversity of niches in its human host. Aside from the classical manifestations of S. aureus-induced diseases, the pathogen also invades and survives within mammalian host cells.The survival strategies of the pathogen are as diverse as strains or host cell types used. S. aureus is able to replicate in the phagosome or freely in the cytoplasm of its host cells. It escapes the phagosome of professional and non-professional phagocytes, subverts autophagy, induces cell death mechanisms such as apoptosis and pyronecrosis, and even can induce anti-apoptotic programs in phagocytes. The focus of this review is to present a guide to recent research outlining the variety of intracellular fates of S. aureus.
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Affiliation(s)
- Martin Fraunholz
- Department of Microbiology, Biocenter, University of Würzburg, Würzburg, Germany.
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174
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Inactivation of staphylococcal phenol soluble modulins by serum lipoprotein particles. PLoS Pathog 2012; 8:e1002606. [PMID: 22457627 PMCID: PMC3310821 DOI: 10.1371/journal.ppat.1002606] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 02/10/2012] [Indexed: 01/09/2023] Open
Abstract
Staphylococcus aureus virulence has been associated with the production of phenol soluble modulins (PSM). PSM are known to activate, attract and lyse neutrophils. However, the functional characterizations were generally performed in the absence of human serum. Here, we demonstrate that human serum can inhibit all the previously-described activities of PSM. We observed that serum can fully block both the cell lysis and FPR2 activation of neutrophils. We show a direct interaction between PSM and serum lipoproteins in human serum and whole blood. Subsequent analysis using purified high, low, and very low density lipoproteins (HDL, LDL, and VLDL) revealed that they indeed neutralize PSM. The lipoprotein HDL showed highest binding and antagonizing capacity for PSM. Furthermore, we show potential intracellular production of PSM by S. aureus upon phagocytosis by neutrophils, which opens a new area for exploration of the intracellular lytic capacity of PSM. Collectively, our data show that in a serum environment the function of PSM as important extracellular toxins should be reconsidered. Infections with methicillin-resistant Staphylococcus aureus (MRSA) are difficult to treat because of resistance against standard antibiotics. In contrast to the traditional healthcare-associated (HA-) MRSA strains, community-associated (CA-) MRSA strains cause severe infections in otherwise healthy individuals. CA-MRSA strains display enhanced virulence, spreading more rapidly and causing more severe illness than HA-MRSA strains. Enhanced virulence of CA-MRSA is thought to be associated with the production of several toxins, such as Phenol Soluble Modulins (PSM). PSM have been described to activate, attract and lyse neutrophils. Thus far, previous studies characterizing the functions of PSM were performed in the absence of body fluids. In the current study, we show that human serum strongly inhibits many functions attributed to PSM. We demonstrate that serum lipoprotein particles are responsible for the binding and inhibition of PSM, even when PSM are produced by growing S. aureus in whole blood. Finally, we show production of PSM by S. aureus within neutrophils, suggesting that PSM may play a role intracellularly in a serum-free environment. These findings significantly contribute to our understanding of the function of PSM and strongly suggest that PSM, instead of performing as extracellular toxins, most likely act as intracellular toxins.
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175
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Schmidt T, Zündorf J, Grüger T, Brandenburg K, Reiners AL, Zinserling J, Witte W, Schnitzler N. Phenotyping of Staphylococcus aureus reveals a new virulent ST398 lineage. Clin Microbiol Infect 2012; 19:279-85. [PMID: 22360315 DOI: 10.1111/j.1469-0691.2012.03775.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Staphylococcus aureus sequence type (ST)398, which is commonly found as a colonization strain in pig farming, is emerging more frequently as the cause of human infections. In this study, we analysed ST398 of porcine and human origin at the genetic, protein and immunogenic levels. Although genetic analysis of the genes encoding the major virulence factors revealed the presence of the same genes in all strains studied, the results demonstrated spa type crossing alterations in adhesion abilities in addition to a strongly enhanced lysis activity directly linked to impaired clearance attributable to polymorphonuclear leukocytes (PMNs). This change in virulence pattern indicates high heterogenicity in the ST398 pool that is not based on a different genetic make-up, but probably on variations in the genetic regulation systems. These modifications, which are tightly connected to pathogenicity, cannot be detected by conventional diagnostic methods.
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Affiliation(s)
- T Schmidt
- Federal Institute for Drugs and Medical Devices, L2-Biosafety-Laboratory, Bonn, Germany
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176
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Kiedrowski MR, Kavanaugh JS, Malone CL, Mootz JM, Voyich JM, Smeltzer MS, Bayles KW, Horswill AR. Nuclease modulates biofilm formation in community-associated methicillin-resistant Staphylococcus aureus. PLoS One 2011; 6:e26714. [PMID: 22096493 PMCID: PMC3214024 DOI: 10.1371/journal.pone.0026714] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Accepted: 10/03/2011] [Indexed: 12/13/2022] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging contributor to biofilm-related infections. We recently reported that strains lacking sigma factor B (sigB) in the USA300 lineage of CA-MRSA are unable to develop a biofilm. Interestingly, when spent media from a USA300 sigB mutant was incubated with other S. aureus strains, biofilm formation was inhibited. Following fractionation and mass spectrometry analysis, the major anti-biofilm factor identified in the spent media was secreted thermonuclease (Nuc). Considering reports that extracellular DNA (eDNA) is an important component of the biofilm matrix, we investigated the regulation and role of Nuc in USA300. The expression of the nuc gene was increased in a sigB mutant, repressed by glucose supplementation, and was unaffected by the agr quorum-sensing system. A FRET assay for Nuc activity was developed and confirmed the regulatory results. A USA300 nuc mutant was constructed and displayed an enhanced biofilm-forming capacity, and the nuc mutant also accumulated more high molecular weight eDNA than the WT and regulatory mutant strains. Inactivation of nuc in the USA300 sigB mutant background partially repaired the sigB biofilm-negative phenotype, suggesting that nuc expression contributes to the inability of the mutant to form biofilm. To test the generality of the nuc mutant biofilm phenotypes, the mutation was introduced into other S. aureus genetic backgrounds and similar increases in biofilm formation were observed. Finally, using multiple S. aureus strains and regulatory mutants, an inverse correlation between Nuc activity and biofilm formation was demonstrated. Altogether, our findings confirm the important role for eDNA in the S. aureus biofilm matrix and indicates Nuc is a regulator of biofilm formation.
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Affiliation(s)
- Megan R. Kiedrowski
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jeffrey S. Kavanaugh
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Cheryl L. Malone
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Joe M. Mootz
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jovanka M. Voyich
- Department of Veterinary Microbiology, Montana State University, Bozeman, Montana, United States of America
| | - Mark S. Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Kenneth W. Bayles
- Department of Pathology, Nebraska Medical Center, University of Nebraska, Omaha, Nebraska, United States of America
| | - Alexander R. Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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177
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Pruneau M, Mitchell G, Moisan H, Dumont-Blanchette É, Jacob CL, Malouin F. Transcriptional analysis of antibiotic resistance and virulence genes in multiresistant hospital-acquired MRSA. ACTA ACUST UNITED AC 2011; 63:54-64. [DOI: 10.1111/j.1574-695x.2011.00830.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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178
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Characterization of Staphylococcus aureus cardiolipin synthases 1 and 2 and their contribution to accumulation of cardiolipin in stationary phase and within phagocytes. J Bacteriol 2011; 193:4134-42. [PMID: 21665977 DOI: 10.1128/jb.00288-11] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In many bacteria, including Staphylococcus aureus, progression from the logarithmic to the stationary phase is accompanied by conversion of most of bacterial membrane phosphatidylglycerol (PG) to cardiolipin (CL). Phagocytosis of S. aureus by human neutrophils also induces the conversion of most bacterial PG to CL. The genome of all sequenced strains of S. aureus contains two open reading frames (ORFs) predicting proteins encoded with ∼30% identity to the principal CL synthase (cls) of Escherichia coli. To test whether these ORFs (cls1 and cls2) encode cardiolipin synthases and contribute to CL accumulation in S. aureus, we expressed these proteins in a cls strain of E. coli and created isogenic single and double mutants in S. aureus. The expression of either Cls1 or Cls2 in CL-deficient E. coli resulted in CL accumulation in the stationary phase. S. aureus with deletion of both cls1 and cls2 showed no detectable CL accumulation in the stationary phase or after phagocytosis by neutrophils. CL accumulation in the stationary phase was due almost solely to Cls2, whereas both Cls1 and Cls2 contributed to CL accumulation following phagocytosis by neutrophils. Differences in the relative contributions of Cls1 and Cls2 to CL accumulation under different triggering conditions suggest differences in the role and regulation of these two enzymes.
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179
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Uriarte SM, Rane MJ, Luerman GC, Barati MT, Ward RA, Nauseef WM, McLeish KR. Granule exocytosis contributes to priming and activation of the human neutrophil respiratory burst. THE JOURNAL OF IMMUNOLOGY 2011; 187:391-400. [PMID: 21642540 DOI: 10.4049/jimmunol.1003112] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of exocytosis in the human neutrophil respiratory burst was determined using a fusion protein (TAT-SNAP-23) containing the HIV transactivator of transcription (TAT) cell-penetrating sequence and the N-terminal SNARE domain of synaptosome-associated protein-23 (SNAP-23). This agent inhibited stimulated exocytosis of secretory vesicles and gelatinase and specific granules but not azurophil granules. GST pulldown showed that TAT-SNAP-23 bound to the combination of vesicle-associated membrane protein-2 and syntaxin-4 but not to either individually. TAT-SNAP-23 reduced phagocytosis-stimulated hydrogen peroxide production by 60% without affecting phagocytosis or generation of HOCl within phagosomes. TAT-SNAP-23 had no effect on fMLF-stimulated superoxide release but significantly inhibited priming of this response by TNF-α and platelet-activating factor. Pretreatment with TAT-SNAP-23 inhibited the increase in plasma membrane expression of gp91(phox) in TNF-α-primed neutrophils, whereas TNF-α activation of ERK1/2 and p38 MAPK was not affected. The data demonstrate that neutrophil granule exocytosis contributes to phagocytosis-induced respiratory burst activity and plays a critical role in priming of the respiratory burst by increasing expression of membrane components of the NADPH oxidase.
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Affiliation(s)
- Silvia M Uriarte
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
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180
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Thoendel M, Kavanaugh JS, Flack CE, Horswill AR. Peptide signaling in the staphylococci. Chem Rev 2010; 111:117-51. [PMID: 21174435 DOI: 10.1021/cr100370n] [Citation(s) in RCA: 288] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Matthew Thoendel
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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