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Oral intake of xanthohumol attenuates lipoteichoic acid-induced inflammatory response in human PBMCs. Eur J Nutr 2022; 61:4155-4166. [PMID: 35857130 DOI: 10.1007/s00394-022-02964-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 07/08/2022] [Indexed: 11/04/2022]
Abstract
PURPOSE The aim of the study was to determine if xanthohumol, a prenylated chalcone found in Hop (Humulus lupulus), has anti-inflammatory effects in healthy humans if applied in low doses achievable through dietary intake. METHODS In a placebo-controlled single-blinded cross-over design study, 14 healthy young men and women either consumed a beverage containing 0.125 mg xanthohumol or a placebo. Peripheral blood mononuclear cells (PBMCs) were isolated before and 1 h after the intake of the beverages. Subsequently, PBMCs were stimulated with or without lipoteichoic acid (LTA) for 24 and 48 h. Concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6) and soluble cluster of differentiation (sCD14) protein were determined in cell culture supernatant. Furthermore, hTLR2 transfected HEK293 cells were stimulated with LTA in the presence or absence of xanthohumol and sCD14. RESULTS The stimulation of PBMCs with LTA for 24 and 48 h resulted in a significant induction of IL-1β, IL-6, and sCD14 protein release in PBMCs of both, fasted subjects and subjects after the ingestion of the placebo. In contrast, after ingesting xanthohumol, LTA-dependent induction of IL-1β, IL-6, and sCD14 protein release from PBMCs was not significantly higher than in unstimulated cells after 48 h. In hTLR2 transfected HEK293 cells xanthohumol significantly suppressed the LTA-dependent activation of cells, an effect attenuated when cells were co-incubated with sCD14. CONCLUSION The results of our study suggest that an ingestion of low doses of xanthohumol can suppress the LTA-dependent stimulation of PBMCs through mechanisms involving the interaction of CD14 with TLR2. Study registered at ClinicalTrials.gov (NCT04847193, 22.03.2022).
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Integrin β3 Modulates TLR4-Mediated Inflammation by Regulation of CD14 Expression in Macrophages in Septic Condition. Shock 2021; 53:335-343. [PMID: 31135705 DOI: 10.1097/shk.0000000000001383] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Sepsis is a major challenge in clinical practice and responsible for high mortality. Recent studies indicated that integrins participated in toll-like-receptor (TLR)-mediated innate immunity. In the present study, we investigated the mechanism of integrin β3 and TLR4 signaling using a cecal ligation and puncture (CLP)-induced sepsis and lipopolysaccharide (LPS)-treated macrophage cell model. In a lethal CLP model, the survival rate of integrin β3 mice was higher than that of wild-type mice. The levels of alanine aminotransferase, aspartate transaminase, creatinine, blood urea nitrogen , and lactate dehydrogenase in the serum and cluster of differentiation 14 (CD14) protein expression in the tissues were significantly decreased in integrin β3 mice. A similar effect with regard to CD14 down-regulation was observed in septic TLR4 mice. In wild-type macrophages, the inhibition of integrin β3 by P11 or with a specific antibody, inhibited TNF-α, and IL-6 release at the early time period of LPS stimulation. However, during the late periods of LPS stimulation this effect was not noted. CD14 expression levels had no change in such treatment. In contract, LPS-induced TNF-α and IL-6 release and LPS-induced CD14 expression were significantly decreased in integrin β3macrophages. The inhibition of the TLR4 pathway by TAK-242, or in TLR4 mutant macrophages abolished LPS-induced CD14 expression. Integrin β3 pathway activation by vitronectin exhibited no effect in CD14 expression. Furthermore, recombinant CD14 protein stimulation reversed integrin β3 deficiency and caused lower TNF-α and IL-6 release. Moreover, the molecular interaction of TLR4 and integrin β3 was significantly increased following LPS stimulation. In conclusion, integrin β3 positively regulated TLR4-mediated inflammatory responses via CD14 expression in macrophages in septic condition. Specifically targeting integrin β3/TLR4-CD14 signaling pathway may be a potential treatment strategy for polymicrobial sepsis.
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Kang Y, Wu T, He Y, He Y, Zhao D. Elf4 regulates lysosomal biogenesis and the mTOR pathway to promote clearance of Staphylococcus aureus in macrophages. FEBS Lett 2021; 595:881-891. [PMID: 33423322 DOI: 10.1002/1873-3468.14037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 11/10/2022]
Abstract
Staphylococcus aureus is a major cause of infectious disease. Macrophages can directly destroy most of the invading bacteria through the phagolysosomal pathway. E74-like factor 4 (Elf4) is one of the important transcription factors that controls diverse pathogens, but the role of Elf4 in macrophage-mediated S. aureus eradication is unknown. Our data show that Elf4 is induced by S. aureus in macrophages. Elevated expression of Elf4 results in decreased bacterial load and inflammatory responses during S. aureus infection in vivo and in vitro. Elf4-overexpressed macrophages have decreased mTOR activity and increased lysosomal mass. Collectively, these results suggest that S. aureus induces Elf4 expression, which enhances lysosomal function and increases the capacity of macrophages to eliminate intracellular pathogens.
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Affiliation(s)
- Yanhua Kang
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Tingyue Wu
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Yan He
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Yunfan He
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Dongjiu Zhao
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
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Naik P, Joseph J. Difference in Host Immune response to Methicillin-Resistant and Methicillin Sensitive Staphylococcus aureus (MRSA and MSSA) Endophthalmitis. Ocul Immunol Inflamm 2021; 30:1044-1054. [PMID: 33560179 DOI: 10.1080/09273948.2020.1859551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE The study aimed to understand the differential immune response of methicillin susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains in in vitro models of endophthalmitis. METHODS Retinal pigment epithelium (RPE) and microglia cells (CHME-3) were exposed to MRSA and MSSA strains and analyzed for expression of inflammatory mediators by real-time quantitative PCR and validated by ELISA or immunofluorescence assay. Heatmap and STRING analysis was used to assess the differential immune expression. RESULTS Both microglia and RPE expressed TLR-2, TLR-1, TLR-6, and TLR -9 after challenge with MRSA and MSSA strains though the expression varied. MRSA-infected cells induced higher expression of IL-1β, IL-8, 1 L-10, IL-6, and GM-CSF, while TNF-α and IFN-ϒ were downregulated in comparison to MSSA-infected cells. We also demonstrate that MRSA infection leads to increased activation of MMP-9 and MMP-2 in RPE cells, while microglia expressed only MMP-9 in MRSA-infected cells. CONCLUSIONS MRSA strain can induce an exacerbated immune response in retinal cells. Giving clues for potential targets in immunomodulatory therapies.
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Affiliation(s)
- Poonam Naik
- Jhaveri Microbiology Centre, Brien Holden Eye Research Centre, L. V. Prasad Eye Institute, Hyderabad, Telangana, India.,Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Joveeta Joseph
- Jhaveri Microbiology Centre, Brien Holden Eye Research Centre, L. V. Prasad Eye Institute, Hyderabad, Telangana, India
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5
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Harada S, Kawada H, Maehana S, Matsui H, Kubo M, Kojima F, Kitasato H, Katagiri M. Panton-Valentine Leukocidin Induces Cytokine Release and Cytotoxicity Mediated by the C5a Receptor on Rabbit Alveolar Macrophages. Jpn J Infect Dis 2021; 74:352-358. [PMID: 33518621 DOI: 10.7883/yoken.jjid.2020.657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Necrotizing pneumonia caused by Panton-Valentine leukocidin (PVL)-positive community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has high mortality rates and is currently a serious clinical issue. PVL is a two-component toxin (LukS-PV and LukF-PV). It can cause necrosis in target cells by forming pores consisting of an octamer comprised of LukS-PV and LukF-PV. However, considering the specificity of PVL towards several target cells and species, the specific effect of PVL remains controversial. Therefore, we focused on necrotizing pneumonia caused by PVL-positive S. aureus and clarified the effect of PVL on alveolar macrophages, which play a central role in innate immunity in the alveolar space. We constructed recombinant PVL (rPVL) components and stimulated alveolar macrophages isolated from rabbits to evaluate cytotoxicity and pro-inflammatory cytokine release. Recombinant LukS-PV (rLukS-PV), but not recombinant LukF-PV (rLukF-PV), induced pro-inflammatory cytokine release. Specifically, tumor necrosis factor (TNF)-α release was mediated by the C5a receptor (C5aR) expressed on rabbit alveolar macrophages, and the toxicity of rPVL, consisting of rLukS-PV and rLukF-PV, towards rabbit alveolar macrophages was mediated by the same receptor. Overall, our findings shed light on the C5aR-mediated cytotoxic effect of PVL on alveolar macrophages, which may be useful for understanding the mechanism of necrotizing pneumonia caused by PVL.
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Affiliation(s)
- Shinya Harada
- Kitasato University Graduate School of Medical Sciences, Japan.,Department of Respiratory Medicine, Kitasato University Hospital, Japan
| | - Hayato Kawada
- Department of Parasitology and Tropical Medicine, Kitasato University School of Medicine, Japan
| | - Shotaro Maehana
- Department of Microbiology, Kitasato University School of Allied Health Sciences, Japan
| | - Hidehito Matsui
- Ōmura Satoshi Memorial Institute, Kitasato University, Japan
| | - Makoto Kubo
- Division of Immunology II, Kitasato University School of Allied Health Sciences, Japan
| | - Fumiaki Kojima
- Department of Pharmacology, Kitasato University School of Allied Health Sciences, Japan
| | - Hidero Kitasato
- Department of Microbiology, Kitasato University School of Allied Health Sciences, Japan
| | - Masato Katagiri
- Kitasato University Graduate School of Medical Sciences, Japan.,Department of Respiratory Medicine, Kitasato University Hospital, Japan.,Department of Clinical Physiology, Kitasato University School of Allied Health Sciences, Japan
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Baishya J, Bisht K, Rimbey JN, Yihunie KD, Islam S, Al Mahmud H, Waller JE, Wakeman CA. The Impact of Intraspecies and Interspecies Bacterial Interactions on Disease Outcome. Pathogens 2021; 10:96. [PMID: 33494265 PMCID: PMC7909810 DOI: 10.3390/pathogens10020096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/10/2021] [Accepted: 01/18/2021] [Indexed: 11/16/2022] Open
Abstract
The human microbiota is an array of microorganisms known to interact with the host and other microbes. These interactions can be competitive, as microbes must adapt to host- and microorganism-related stressors, thus producing toxic molecules, or cooperative, whereby microbes survive by maintaining homeostasis with the host and host-associated microbial communities. As a result, these microbial interactions shape host health and can potentially result in disease. In this review, we discuss these varying interactions across microbial species, their positive and negative effects, the therapeutic potential of these interactions, and their implications on our knowledge of human well-being.
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Affiliation(s)
| | | | | | | | | | | | | | - Catherine A. Wakeman
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA; (J.B.); (K.B.); (J.N.R.); (K.D.Y.); (S.I.); (H.A.M.); (J.E.W.)
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7
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Kumar S, Sunagar R, Gosselin E. Bacterial Protein Toll-Like-Receptor Agonists: A Novel Perspective on Vaccine Adjuvants. Front Immunol 2019; 10:1144. [PMID: 31191528 PMCID: PMC6549121 DOI: 10.3389/fimmu.2019.01144] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/07/2019] [Indexed: 12/12/2022] Open
Abstract
Adjuvants have been used in vaccines for over a century, however, the search for safe and effective vaccine adjuvants continues. In recent decades toll-like-receptor (TLR) agonists have been investigated as potential vaccine adjuvants. In this regard, the majority of the currently investigated TLR agonists are non-protein microbial components such as lipopolysaccharides, oligonucleotides, and lipopeptides. On the other hand, a growing number of studies reveal that TLR signaling and immune responses can be activated by numerous bacterial proteins. However, their potential roles as adjuvants have been somewhat overlooked. Herein, we discuss several such bacterial proteins which exhibit adjuvant properties, including the activation of TLR signaling, antigen presenting cell maturation, pro-inflammatory cytokine production and adaptive immune response. The protein nature of these TLR agonists presents several unique features not shared by non-protein TLR agonists. These properties include the amenability for modifying the structure and function as necessary for optimal immunogenicity and minimal toxicity. Protein adjuvants can be genetically fused to protein antigens which ensure the co-delivery of adjuvant-antigen not only into the same cell but also in the same endocytic cargo, leading to more effective activation of innate and adaptive immune response.
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Affiliation(s)
- Sudeep Kumar
- Department of Immunology and Microbial Diseases, Albany Medical College, Albany, NY, United States
| | - Raju Sunagar
- Ella Foundation, Genome Valley, Hyderabad, India
| | - Edmund Gosselin
- Department of Immunology and Microbial Diseases, Albany Medical College, Albany, NY, United States
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Fleitas Martínez O, Cardoso MH, Ribeiro SM, Franco OL. Recent Advances in Anti-virulence Therapeutic Strategies With a Focus on Dismantling Bacterial Membrane Microdomains, Toxin Neutralization, Quorum-Sensing Interference and Biofilm Inhibition. Front Cell Infect Microbiol 2019; 9:74. [PMID: 31001485 PMCID: PMC6454102 DOI: 10.3389/fcimb.2019.00074] [Citation(s) in RCA: 145] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 03/05/2019] [Indexed: 12/11/2022] Open
Abstract
Antimicrobial resistance constitutes one of the major challenges facing humanity in the Twenty-First century. The spread of resistant pathogens has been such that the possibility of returning to a pre-antibiotic era is real. In this scenario, innovative therapeutic strategies must be employed to restrict resistance. Among the innovative proposed strategies, anti-virulence therapy has been envisioned as a promising alternative for effective control of the emergence and spread of resistant pathogens. This review presents some of the anti-virulence strategies that are currently being developed, it will cover strategies focused on quench pathogen quorum sensing (QS) systems, disassemble of bacterial functional membrane microdomains (FMMs), disruption of biofilm formation and bacterial toxin neutralization.
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Affiliation(s)
- Osmel Fleitas Martínez
- Programa de Pós-Graduação em Patologia Molecular, Faculdade de Medicina, Universidade de Brasília, Brasília, Brazil.,Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil
| | - Marlon Henrique Cardoso
- Programa de Pós-Graduação em Patologia Molecular, Faculdade de Medicina, Universidade de Brasília, Brasília, Brazil.,Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil.,S-inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
| | - Suzana Meira Ribeiro
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal da Grande Dourados, Dourados, Brazil
| | - Octavio Luiz Franco
- Programa de Pós-Graduação em Patologia Molecular, Faculdade de Medicina, Universidade de Brasília, Brasília, Brazil.,Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil.,S-inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
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Abstract
An overwhelming immune response, particularly from macrophages, plays a critical role in survival and organ damage in sepsis patients. Toll-like receptors (TLRs) are important receptors to recognize the conserved motifs expressed by invading bacteria. The TLRs except TLR3 signal via a MyD88-dependent pathway. TLR3 uses a TRIF-dependent pathway, while TLR4 uses both MyD88 and TRIF-dependent pathways. Previous studies indicated that CD14 was necessary for TLRs-dependent production of pro-inflammatory cytokines. Blocking CD14 protected against the deleterious systemic inflammatory response associated with sepsis. The aim of this study was to determine the signaling pathway of TLR activation-induced CD14 expression in models of polymicrobial sepsis and in peritoneal macrophages. We found that CD14 expression was upregulated in the lung, liver, and kidney of septic mice induced by cecal ligation puncture. In cultured peritoneal macrophages, specific agonists for all TLRs, except for TLR3, increased CD14 expression. Lipopolysaccharide-induced upregulation of CD14 was abolished in peritoneal macrophages from MyD88 KO mice but increased in TRIF inhibitor, resveratrol pretreated wild-type macrophages. Moreover, MyD88 KO, but not TRIF KO mice, showed a decreased CD14 expression in the tissue of septic mice, which was associated with a strongly attenuated inflammatory response and increased survival rate. These data suggest that a MyD88-dependent and TRIF-independent pathway of TLR is activated in upregulating CD14 expression under septic conditions. This study deciphers a critical cross-talk between TLRs and CD14.
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10
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Skerrett SJ, Braff MH, Liggitt HD, Rubens CE. Toll-like receptor 2 has a prominent but nonessential role in innate immunity to Staphylococcus aureus pneumonia. Physiol Rep 2018; 5:5/21/e13491. [PMID: 29142002 PMCID: PMC5688782 DOI: 10.14814/phy2.13491] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 10/08/2017] [Accepted: 10/11/2017] [Indexed: 11/30/2022] Open
Abstract
Staphylococcus aureus is an important cause of acute bacterial pneumonia. Toll‐like receptor 2 (TLR2) recognizes multiple components of the bacterial cell wall and activates innate immune responses to gram‐positive bacteria. We hypothesized that TLR2 would have an important role in pulmonary host defense against S. aureus. TLR null (TLR2−/−) mice and wild type (WT) C57BL/6 controls were challenged with aerosolized S. aureus at a range of inocula for kinetic studies of cytokine and antimicrobial peptide expression, lung inflammation, bacterial killing by alveolar macrophages, and bacterial clearance. Survival was measured after intranasal infection. Pulmonary induction of most pro‐inflammatory cytokines was significantly blunted in TLR2−/− mice 4 and 24 h after infection in comparison with WT controls. Bronchoalveolar concentrations of cathelicidin‐related antimicrobial peptide also were reduced in TLR2−/− mice. Lung inflammation, measured by enumeration of bronchoalveolar neutrophils and scoring of histological sections, was significantly blunted in TLR2−/− mice. Phagocytosis of S. aureus by alveolar macrophages in vivo after low‐dose infection was unimpaired, but viability of ingested bacteria was significantly greater in TLR2−/− mice. Bacterial clearance from the lungs was slightly impaired in TLR2−/− mice after low‐dose infection only; bacterial elimination from the lungs was slightly accelerated in the TLR2−/− mice after high‐dose infection. Survival after high‐dose intranasal challenge was 50–60% in both groups. TLR2 has a significant role in early innate immune responses to S. aureus in the lungs but is not required for bacterial clearance and survival from S. aureus pneumonia.
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Affiliation(s)
- Shawn J Skerrett
- Department of Medicine, University of Washington, Seattle, Washington
| | - Marissa H Braff
- Seattle Children's Hospital Research Institute, Seattle, Washington
| | - H Denny Liggitt
- Department of Comparative Medicine, University of Washington, Seattle, Washington
| | - Craig E Rubens
- Seattle Children's Hospital Research Institute, Seattle, Washington
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11
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Skjeflo EW, Christiansen D, Fure H, Ludviksen JK, Woodruff TM, Espevik T, Nielsen EW, Brekke OL, Mollnes TE. Staphylococcus aureus-induced complement activation promotes tissue factor-mediated coagulation. J Thromb Haemost 2018; 16:905-918. [PMID: 29437288 DOI: 10.1111/jth.13979] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Indexed: 12/13/2022]
Abstract
Essentials Complement, Toll-like receptors and coagulation cross-talk in the process of thromboinflammation. This is explored in a unique human whole-blood model of S. aureus bacteremia. Coagulation is here shown as a downstream event of C5a-induced tissue factor (TF) production. Combined inhibition of C5 and CD14 efficiently attenuated TF and coagulation. SUMMARY Background There is extensive cross-talk between the complement system, the Toll-like receptors (TLRs), and hemostasis. Consumptive coagulopathy is a hallmark of sepsis, and is often mediated through increased tissue factor (TF) expression. Objectives To study the relative roles of complement, TLRs and TF in Staphylococcus aureus-induced coagulation. Methods Lepirudin-anticoagulated human whole blood was incubated with the three S. aureus strains Cowan, Wood, and Newman. C3 was inhibited with compstatin, C5 with eculizumab, C5a receptor 1 (C5aR1) and activated factor XII with peptide inhibitors, CD14, TLR2 and TF with neutralizing antibodies, and TLR4 with eritoran. Complement activation was measured by ELISA. Coagulation was measured according to prothrombin fragment 1 + 2 (PTF1 + 2 ) determined with ELISA, and TF mRNA, monocyte surface expression and functional activity were measured with quantitative PCR, flow cytometry, and ELISA, respectively. Results All three strains generated substantial and statistically significant amounts of C5a, terminal complement complex, PTF1 + 2 , and TF mRNA, and showed substantial TF surface expression on monocytes and TF functional activity. Inhibition of C5 cleavage most efficiently and significantly inhibited all six markers in strains Cowan and Wood, and five markers in Newman. The effect of complement inhibition was shown to be completely dependent on C5aR1. The C5 blocking effect was equally potentiated when combined with blocking of CD14 or TLR2, but not TLR4. TF blocking significantly reduced PTF1 + 2 levels to baseline levels. Conclusions S. aureus-induced coagulation in human whole blood was mainly attributable to C5a-induced mRNA upregulation, monocyte TF expression, and plasma TF activity, thus underscoring complement as a key player in S. aureus-induced coagulation.
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Affiliation(s)
- E W Skjeflo
- Research Laboratory, Nordland Hospital, Bodø, Norway
- Faculty of Health Sciences, K. G. Jebsen TREC, UiT - The Arctic University of Norway, Tromsø, Norway
| | | | - H Fure
- Research Laboratory, Nordland Hospital, Bodø, Norway
| | - J K Ludviksen
- Research Laboratory, Nordland Hospital, Bodø, Norway
| | - T M Woodruff
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - T Espevik
- Center of Molecular Inflammation Research, and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - E W Nielsen
- Faculty of Health Sciences, K. G. Jebsen TREC, UiT - The Arctic University of Norway, Tromsø, Norway
- Department of Anesthesiology, Nordland Hospital, Bodø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | - O L Brekke
- Research Laboratory, Nordland Hospital, Bodø, Norway
- Faculty of Health Sciences, K. G. Jebsen TREC, UiT - The Arctic University of Norway, Tromsø, Norway
| | - T E Mollnes
- Research Laboratory, Nordland Hospital, Bodø, Norway
- Faculty of Health Sciences, K. G. Jebsen TREC, UiT - The Arctic University of Norway, Tromsø, Norway
- Center of Molecular Inflammation Research, and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Immunology, Oslo University Hospital and K. G. Jebsen IRC, University of Oslo, Oslo, Norway
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Tanaka J, Hirayama F, Yanase S, Uno S, Nakae T, Kamizono A, Hanaki H. Effective concentration of intravenous immunoglobulin for neutralizing Panton-Valentine leukocidin in human blood. J Infect Chemother 2018; 24:383-388. [DOI: 10.1016/j.jiac.2017.12.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 12/01/2017] [Accepted: 12/30/2017] [Indexed: 10/17/2022]
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13
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Anti-endotoxin mechanism of the KW4 peptide in inflammation in RAW 264.7 cells induced by LTA and drug-resistant Staphylococcus aureus 1630. Amino Acids 2017; 50:363-372. [PMID: 29238856 DOI: 10.1007/s00726-017-2518-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/27/2017] [Indexed: 10/18/2022]
Abstract
Drug-resistant microorganism infections cause serious disease and can lead to mortality and morbidity. In particular, Staphylococcus aureus induces pyrogenic and toxigenic infections, and drug-resistance occurs rapidly. Multidrug-resistant S. aureus, such as methicillin-resistant S. aureus and methicillin-sensitive S. aureus, can also cause immunodeficiency and immune deficiency syndrome from lipoteichoic acid. However, antimicrobial peptides, such as KW4, have strong antimicrobial activity, low cytotoxicity, and high neutralization activity against endotoxin substances from Gram-negative bacteria. The objective of this study was to use a synthetic KW4 antimicrobial peptide to evaluate the inhibition of drug-resistance development, antimicrobial activity, and neutralizing activity in S. aureus Gram-positive bacteria. The KW4 peptide showed strong antimicrobial activity against drug-resistant S. aureus strains and significantly increased the anti-neutralizing activity of lipoteichoic acid in S. aureus 1630 drug-resistant bacteria. In addition, S. aureus ATCC 29213 did not develop resistance to KW4 as with other antibiotic drugs. These results suggest that the KW4 peptide is an effective antibiotic and anti-neutralizing agent against multidrug-resistant S. aureus strains.
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14
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Ma L, Yang Y, Sun X, Jiang M, Ma Y, Yang X, Guo Z. Propofol regulates the expression of TLR4 through miR‑21 in human umbilical vein endothelial cells. Mol Med Rep 2017; 16:9074-9080. [PMID: 29039542 DOI: 10.3892/mmr.2017.7765] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 07/13/2017] [Indexed: 11/05/2022] Open
Abstract
Propofol (2,6-diisopropylphenol) is one of the most commonly used intravenous anesthetics. Anesthetics can regulate the inflammatory process; however, the mechanism remains to be fully elucidated. The present study aimed to investigate whether and how propofol affects the inflammatory reaction in human umbilical vein endothelial cells (HUVECs). The expression levels of Toll‑like receptor 4 (TLR4) and cluster of differentiation 14 (CD14) were determined in HUVECs treated with propofol and lipopolysaccharide (LPS) using western blot and reverse transcription‑quantitative polymerase chain reaction analyses. In addition, whether propofol regulated the expression of TLR4 though microRNA (miR)‑21 was examined. The results showed that LPS promoted the expression levels of TLR4, CD14 and tumor necrosis factor α (TNFα), and suppressed the expression of miR‑21 in HUVECs. Propofol suppressed the expression levels of TLR4, CD14 and TNFα, and upregulated the expression of miR‑21 in a concentration‑dependent manner. miR‑21 downregulated the expression of TLR4 at the mRNA and protein levels, whereas the miR‑21 mimic reversed the effect of LPS on the expression of TLR4. In addition, the miR‑21 inhibitor inhibited the downregulatory effect of propofol on the expression of TLR4. TargetScan analysis showed that TLR4 was included in the list of targets of miR‑21. Fluorescent reporter assays showed that the miR‑21 mimic and propofol treatment reduced the fluorescence intensity in cells transfected with a reporter vector containing the wild‑type TLR4 3'‑untranslated region. Taken together, the results of the present study demonstrated that propofol regulated the expression of TLR4 in HUVECs through miR‑21.
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Affiliation(s)
- Ling Ma
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Yue Yang
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Xuechen Sun
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Meiling Jiang
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Yang Ma
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Xilun Yang
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Zhiwei Guo
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
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15
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Yu B, Shen Y, Qiao J, Cui Q. Geniposide attenuates Staphylococcus aureus-induced pneumonia in mice by inhibiting NF-κB activation. Microb Pathog 2017; 112:117-121. [PMID: 28958950 DOI: 10.1016/j.micpath.2017.09.050] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 09/11/2017] [Accepted: 09/24/2017] [Indexed: 02/07/2023]
Abstract
Staphylococcus aureus (S. aureus) is a major cause of pneumonia that often affects young and immunocompetent patients. Inflammation plays an important role in the development of S. aureus-induced pneumonia. Geniposide, a major iridoid glucoside component of gardenia fruit, has been reported to have anti-inflammatory and anti-oxidative effects. The purpose of this study was to investigate the protective effects of geniposide on S. aureus-induced pneumonia in mice. Lung histopathological changes were detected by hematoxylin-eosin (H&E) staining. Lung myeloperoxidase (MPO) activity, wet-to-dry (W/D) ratio, and inflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) were measured. The results showed that S. aureus-induced lung histopathological changes were attenuated by geniposide. S. aureus-induced MPO activity and lung W/D ratio were inhibited by treatment of geniposide. Furthermore, the levels of TNF-α and IL-1β in the BALF were also suppressed by geniposide. In addition, geniposide significantly inhibited S. aureus-induced nuclear factor kappa B (NF-κB) activation. Taken together, these results showed that geniposide inhibited S. aureus-induced pneumonia in mice by inhibiting NF-κB signaling pathway. Geniposide might be used as a potential agent for the treatment of S. aureus-induced pneumonia.
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Affiliation(s)
- Bin Yu
- Department of Pediatrics, The First Hospital of Harbin Medical University, Harbin, China
| | - Yongbin Shen
- Department of Vascular Surgery, The Second Hospital of Harbin Medical University, Harbin, China
| | - Jiutao Qiao
- Department of Orthopedics, The Second Hospital of Harbin Medical University, Harbin, China
| | - Qingbo Cui
- Department of Pediatric Surgery, The Second Hospital of Harbin Medical University, Harbin, China.
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16
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Landrum ML, Lalani T, Niknian M, Maguire JD, Hospenthal DR, Fattom A, Taylor K, Fraser J, Wilkins K, Ellis MW, Kessler PD, Fahim REF, Tribble DR. Safety and immunogenicity of a recombinant Staphylococcus aureus α-toxoid and a recombinant Panton-Valentine leukocidin subunit, in healthy adults. Hum Vaccin Immunother 2017; 13:791-801. [PMID: 28010246 PMCID: PMC5404372 DOI: 10.1080/21645515.2016.1248326] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/29/2016] [Accepted: 10/11/2016] [Indexed: 01/01/2023] Open
Abstract
We conducted a randomized, double-blind, placebo-controlled dose-escalation study in healthy adults to evaluate the safety and immunogenicity of recombinant Staphylococcus aureus candidate vaccine antigens, recombinant α-toxoid (rAT) and a sub-unit of Panton-Valentine leukocidin (rLukS-PV). 176 subjects were enrolled and randomized within 1 of 11 treatment cohorts: monovalent rAT or rLukS-PV dosages of 10, 25, 50, and 100 μg; bivalent rAT:rLukS dosages of 10:10, 25:25, and 50:50 μg; and alum or saline placebo. All subjects were assessed at Days 0, 7, 14, 28, and 84. Subjects in the 50:50 μg bivalent cohort received a second injection on Day 84 and were assessed on Days 98 and 112. Incidence and severity of reactogenicity and adverse events (AEs) were compared. Geometric mean serum concentrations (GMC) and neutralizing activity of anti-rAT and anti-rLukS-PV IgG were assessed. Reactogenicity incidence was significantly higher in vaccine than placebo recipients (77% versus 55%, respectively; p = 0.006). However, 77% of reactogenicity events were mild and 19% were moderate in severity. The AE incidence and severity were similar between the cohorts. All monovalent and bivalent rAT dosages resulted in a significant increase in the anti-rAT IgG and anti- rLukS-PV GMCs between day 0 and 28 compared with placebo, and persisted through Day 84. Exploratory subgroup analyses suggested a higher GMC and neutralizing antibody titers for the 50 μg monovalent or bivalent rAT and rLukS-PV dose as compared to the other doses. No booster effect was observed after administration of the second dose. We conclude that the rAT and rLukS-PV vaccine formulations were well-tolerated and had a favorable immunogenicity profile, producing antibody with neutralizing activity through day 84. There was no benefit observed with a booster dose of the vaccine.
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Affiliation(s)
- Michael L. Landrum
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, USA
- Division of Infectious Diseases, San Antonio Military Medical Center, Fort Sam Houston, TX, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Tahaniyat Lalani
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
- Division of Infectious Diseases, Naval Medical Center Portsmouth, Portsmouth, VA, USA
| | | | - Jason D. Maguire
- Division of Infectious Diseases, Naval Medical Center Portsmouth, Portsmouth, VA, USA
| | - Duane R. Hospenthal
- Division of Infectious Diseases, San Antonio Military Medical Center, Fort Sam Houston, TX, USA
| | - Ali Fattom
- Nabi Biopharmaceuticals, Rockville, MD, USA
| | | | - Jamie Fraser
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Kenneth Wilkins
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Michael W. Ellis
- Infectious Diseases Division, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | | | | | - David R. Tribble
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, USA
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17
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Correa-Jiménez O, Pinzón-Redondo H, Reyes N. High frequency of Panton-Valentine leukocidin in Staphylococcus aureus causing pediatric infections in the city of Cartagena-Colombia. J Infect Public Health 2016; 9:415-20. [DOI: 10.1016/j.jiph.2015.10.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/24/2015] [Indexed: 12/26/2022] Open
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18
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Greco SH, Mahmood SK, Vahle AK, Ochi A, Batel J, Deutsch M, Barilla R, Seifert L, Pachter HL, Daley D, Torres-Hernandez A, Hundeyin M, Mani VR, Miller G. Mincle suppresses Toll-like receptor 4 activation. J Leukoc Biol 2016; 100:185-94. [PMID: 26747838 PMCID: PMC6608084 DOI: 10.1189/jlb.3a0515-185r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 11/28/2015] [Accepted: 12/22/2015] [Indexed: 11/24/2022] Open
Abstract
Regulation of Toll-like receptor responses is critical for limiting tissue injury and autoimmunity in both sepsis and sterile inflammation. We found that Mincle, a C-type lectin receptor, regulates proinflammatory Toll-like receptor 4 signaling. Specifically, Mincle ligation diminishes Toll-like receptor 4-mediated inflammation, whereas Mincle deletion or knockdown results in marked hyperresponsiveness to lipopolysaccharide in vitro, as well as overwhelming lipopolysaccharide-mediated inflammation in vivo. Mechanistically, Mincle deletion does not up-regulate Toll-like receptor 4 expression or reduce interleukin 10 production after Toll-like receptor 4 ligation; however, Mincle deletion decreases production of the p38 mitogen-activated protein kinase-dependent inhibitory intermediate suppressor of cytokine signaling 1, A20, and ABIN3 and increases expression of the Toll-like receptor 4 coreceptor CD14. Blockade of CD14 mitigates the increased sensitivity of Mincle(-/-) leukocytes to Toll-like receptor 4 ligation. Collectively, we describe a major role for Mincle in suppressing Toll-like receptor 4 responses and implicate its importance in nonmycobacterial models of inflammation.
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Affiliation(s)
- Stephanie H Greco
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Syed Kashif Mahmood
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Anne-Kristin Vahle
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Atsuo Ochi
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Jennifer Batel
- Department of Cell Biology, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA
| | - Michael Deutsch
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Rocky Barilla
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Lena Seifert
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - H Leon Pachter
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Donnele Daley
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Alejandro Torres-Hernandez
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Mautin Hundeyin
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - Vishnu R Mani
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and
| | - George Miller
- Department of Surgery, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA; and Department of Cell Biology, S. Arthur Localio Laboratory, New York University School of Medicine, New York, NY, USA
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19
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Piperine Plays an Anti-Inflammatory Role in Staphylococcus aureus Endometritis by Inhibiting Activation of NF-κB and MAPK Pathways in Mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 2016:8597208. [PMID: 27293467 PMCID: PMC4880693 DOI: 10.1155/2016/8597208] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 04/01/2016] [Accepted: 04/06/2016] [Indexed: 01/07/2023]
Abstract
Endometritis is commonly caused by pathogenic microorganisms, including Staphylococcus aureus (S. aureus). Piperine, which is a natural medicine, has shown a variety of biological activities. To explore the effect and mechanism of piperine on S. aureus endometritis, a mouse model of S. aureus endometritis was successfully established in the present study. Histopathological changes were observed with H&E staining, cytokines were analyzed by ELISA, mRNA was analyzed by qPCR, and proteins were detected by western blot. The results showed that piperine could significantly alleviate inflammatory injury in S. aureus endometritis. The qPCR and ELISA results showed that piperine effectively reduced the S. aureus-induced overexpression of TNF-α, IL-1β, and IL-6 but increased the expression of IL-10. The S. aureus-induced inflammation was related to TLR-2 and TLR-4 because the results showed that their expression was increased in S. aureus infection but then decreased with piperine treatment. To further confirm that piperine caused an anti-inflammatory response by targeting NF-κB and MAPKs, the expression of I-κB, p65, p38, ERK, and JNK was measured. The phosphorylation of I-κB, p65, p38, ERK, and JNK was inhibited by piperine in a dose-dependent manner. All of the results indicated that piperine may be a potential anti-inflammatory drug both in endometritis and in other S. aureus-induced diseases.
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20
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Kong C, Neoh HM, Nathan S. Targeting Staphylococcus aureus Toxins: A Potential form of Anti-Virulence Therapy. Toxins (Basel) 2016; 8:toxins8030072. [PMID: 26999200 PMCID: PMC4810217 DOI: 10.3390/toxins8030072] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/03/2016] [Accepted: 03/10/2016] [Indexed: 01/01/2023] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen and the leading cause of a wide range of severe clinical infections. The range of diseases reflects the diversity of virulence factors produced by this pathogen. To establish an infection in the host, S. aureus expresses an inclusive set of virulence factors such as toxins, enzymes, adhesins, and other surface proteins that allow the pathogen to survive under extreme conditions and are essential for the bacteria’s ability to spread through tissues. Expression and secretion of this array of toxins and enzymes are tightly controlled by a number of regulatory systems. S. aureus is also notorious for its ability to resist the arsenal of currently available antibiotics and dissemination of various multidrug-resistant S. aureus clones limits therapeutic options for a S. aureus infection. Recently, the development of anti-virulence therapeutics that neutralize S. aureus toxins or block the pathways that regulate toxin production has shown potential in thwarting the bacteria’s acquisition of antibiotic resistance. In this review, we provide insights into the regulation of S. aureus toxin production and potential anti-virulence strategies that target S. aureus toxins.
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Affiliation(s)
- Cin Kong
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia.
| | - Hui-min Neoh
- UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, 56000 Cheras, Kuala Lumpur, Malaysia.
| | - Sheila Nathan
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia.
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21
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Reyes-Robles T, Torres VJ. Staphylococcus aureus Pore-Forming Toxins. Curr Top Microbiol Immunol 2016; 409:121-144. [PMID: 27406190 DOI: 10.1007/82_2016_16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Staphylococcus aureus (S. aureus) is a formidable foe equipped with an armamentarium of virulence factors to thwart host defenses and establish a successful infection. Among these virulence factors, S. aureus produces several potent secreted proteins that act as cytotoxins, predominant among them the beta-barrel pore-forming toxins. These toxins play several roles in pathogenesis, including disruption of cellular adherens junctions at epithelial barriers, alteration of intracellular signaling events, modulation of host immune responses, and killing of eukaryotic immune and non-immune cells. This chapter provides an updated overview on the S. aureus beta-barrel pore-forming cytotoxins, the identification of toxin receptors on host cells, and their roles in pathogenesis.
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Affiliation(s)
- Tamara Reyes-Robles
- Department of Microbiology, Microbial Pathogenesis Program, New York University School of Medicine, 522 First Avenue, Smilow Research Building, Room 1010, New York, NY, 10016, USA
| | - Victor J Torres
- Department of Microbiology, Microbial Pathogenesis Program, New York University School of Medicine, 522 First Avenue, Smilow Research Building, Room 1010, New York, NY, 10016, USA.
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22
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Georgakilas AG, Pavlopoulou A, Louka M, Nikitaki Z, Vorgias CE, Bagos PG, Michalopoulos I. Emerging molecular networks common in ionizing radiation, immune and inflammatory responses by employing bioinformatics approaches. Cancer Lett 2015; 368:164-72. [DOI: 10.1016/j.canlet.2015.03.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/16/2015] [Indexed: 12/16/2022]
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23
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Chu KO, Chan KP, Yang YP, Qin YJ, Li WY, Chan SO, Wang CC, Pang CP. Effects of EGCG content in green tea extract on pharmacokinetics, oxidative status and expression of inflammatory and apoptotic genes in the rat ocular tissues. J Nutr Biochem 2015; 26:1357-67. [PMID: 26362107 DOI: 10.1016/j.jnutbio.2015.07.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 05/21/2015] [Accepted: 07/06/2015] [Indexed: 12/31/2022]
Abstract
Green tea extract (GTE) exerts antioxidative activities in ocular tissues of rats, but high levels of (-)-epigallocatechin gallate (EGCG) can induce oxidative stress. In this study, pharmacokinetics, diurnal variation of oxidative status, antioxidation and transcription factors changes in ocular tissues of rats were investigated. Rats were fed intragastrically with GTE and catechin mixtures containing different amounts of EGCG. Plasma and various ocular tissues were taken for pharmacokinetic analysis, oxidation marker testings and gene expression assays. Effects of EGCG on ocular oxidation status were assessed by 8-isoprostane level and reduced/oxidized glutathione ratio. Oxidation, inflammation and apoptosis regulations in retina were evaluated by real-time polymerase chain reaction. Epicatechin, epigallocatechin and EGCG were dominant in various ocular tissues except vitreous humor, where gallocatechin was predominant. Diurnal variation of oxidative status was found in some compartments. GTE caused oxidative stress increase in the plasma, aqueous humor, vitreous humor, cornea and retina but decrease in the lens and choroid-sclera. Catechins mixture containing half dose of EGCG lowered 8-isoprostane in the retina and lens. GTE treatment induced superoxide dismutase 1 and glutathione peroxidase-3 expressions but suppressed catalase in the retina. Our results reveal pro-oxidation of GTE with high EGCG content to the ocular tissues. Optimal EGCG level is needed for protection.
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Affiliation(s)
- Kai On Chu
- Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong; Department of Obstetrics and Gynaecology, the Chinese University of Hong Kong
| | - Kwok Ping Chan
- Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong
| | - Ya Ping Yang
- Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong
| | - Yong Jie Qin
- Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong
| | - Wai Ying Li
- Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong
| | - Sun On Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong
| | - Chi Chiu Wang
- Department of Obstetrics and Gynaecology, the Chinese University of Hong Kong
| | - Chi Pui Pang
- Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong.
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24
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SP-R210 (Myo18A) Isoforms as Intrinsic Modulators of Macrophage Priming and Activation. PLoS One 2015; 10:e0126576. [PMID: 25965346 PMCID: PMC4428707 DOI: 10.1371/journal.pone.0126576] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 04/06/2015] [Indexed: 11/19/2022] Open
Abstract
The surfactant protein (SP-A) receptor SP-R210 has been shown to increase phagocytosis of SP-A-bound pathogens and to modulate cytokine secretion by immune cells. SP-A plays an important role in pulmonary immunity by enhancing opsonization and clearance of pathogens and by modulating macrophage inflammatory responses. Alternative splicing of the Myo18A gene results in two isoforms: SP-R210S and SP-R210L, with the latter predominantly expressed in alveolar macrophages. In this study we show that SP-A is required for optimal expression of SP-R210L on alveolar macrophages. Interestingly, pre-treatment with SP-A prepared by different methods either enhances or suppresses responsiveness to LPS, possibly due to differential co-isolation of SP-B or other proteins. We also report that dominant negative disruption of SP-R210L augments expression of receptors including SR-A, CD14, and CD36, and enhances macrophages' inflammatory response to TLR stimulation. Finally, because SP-A is known to modulate CD14, we used a variety of techniques to investigate how SP-R210 mediates the effect of SP-A on CD14. These studies revealed a novel physical association between SP-R210S, CD14, and SR-A leading to an enhanced response to LPS, and found that SP-R210L and SP-R210S regulate internalization of CD14 via distinct macropinocytosis-like mechanisms. Together, our findings support a model in which SP-R210 isoforms differentially regulate trafficking, expression, and activation of innate immune receptors on macrophages.
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25
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Yıldırım C, Vogel DYS, Hollander MR, Baggen JM, Fontijn RD, Nieuwenhuis S, Haverkamp A, de Vries MR, Quax PHA, Garcia-Vallejo JJ, van der Laan AM, Dijkstra CD, van der Pouw Kraan TCTM, van Royen N, Horrevoets AJG. Galectin-2 induces a proinflammatory, anti-arteriogenic phenotype in monocytes and macrophages. PLoS One 2015; 10:e0124347. [PMID: 25884209 PMCID: PMC4401781 DOI: 10.1371/journal.pone.0124347] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 02/28/2015] [Indexed: 01/02/2023] Open
Abstract
Galectin-2 is a monocyte-expressed carbohydrate-binding lectin, for which increased expression is genetically determined and associated with decreased collateral arteriogenesis in obstructive coronary artery disease patients. The inhibiting effect of galectin-2 on arteriogenesis was confirmed in vivo, but the mechanism is largely unknown. In this study we aimed to explore the effects of galectin-2 on monocyte/macrophage phenotype in vitro and vivo, and to identify the receptor by which galectin-2 exerts these effects. We now show that the binding of galectin-2 to different circulating human monocyte subsets is dependent on monocyte surface expression levels of CD14. The high affinity binding is blocked by an anti-CD14 antibody but not by carbohydrates, indicating a specific protein-protein interaction. Galectin-2 binding to human monocytes modulated their transcriptome by inducing proinflammatory cytokines and inhibiting pro-arteriogenic factors, while attenuating monocyte migration. Using specific knock-out mice, we show that galectin-2 acts through the CD14/toll-like receptor (TLR)-4 pathway. Furthermore, galectin-2 skews human macrophages to a M1-like proinflammatory phenotype, characterized by a reduced motility and expression of an anti-arteriogenic cytokine/growth factor repertoire. This is accompanied by a switch in surface protein expression to CD40-high and CD206-low (M1). In a murine model we show that galectin-2 administration, known to attenuate arteriogenesis, leads to increased numbers of CD40-positive (M1) and reduced numbers of CD206-positive (M2) macrophages surrounding actively remodeling collateral arteries. In conclusion galectin-2 is the first endogenous CD14/TLR4 ligand that induces a proinflammatory, non-arteriogenic phenotype in monocytes/macrophages. Interference with CD14-Galectin-2 interaction may provide a new intervention strategy to stimulate growth of collateral arteries in genetically compromised cardiovascular patients.
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Affiliation(s)
- Cansu Yıldırım
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Daphne Y. S. Vogel
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | | | - Josefien M. Baggen
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Ruud D. Fontijn
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Sylvia Nieuwenhuis
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Anouk Haverkamp
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Margreet R. de Vries
- Dept of Vascular Surgery, Einthoven Laboratories, Leiden University Medical Centre, Leiden, the Netherlands
| | - Paul H. A. Quax
- Dept of Vascular Surgery, Einthoven Laboratories, Leiden University Medical Centre, Leiden, the Netherlands
| | - Juan J. Garcia-Vallejo
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Anja M. van der Laan
- Dept of Cardiology, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
| | - Christine D. Dijkstra
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
| | | | - Niels van Royen
- Dept of Cardiology, VU University Medical Centre, Amsterdam, the Netherlands
| | - Anton J. G. Horrevoets
- Dept of Molecular Cell Biology and Immunology, VU University Medical Centre, Amsterdam, the Netherlands
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26
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The bicomponent pore-forming leucocidins of Staphylococcus aureus. Microbiol Mol Biol Rev 2015; 78:199-230. [PMID: 24847020 DOI: 10.1128/mmbr.00055-13] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ability to produce water-soluble proteins with the capacity to oligomerize and form pores within cellular lipid bilayers is a trait conserved among nearly all forms of life, including humans, single-celled eukaryotes, and numerous bacterial species. In bacteria, some of the most notable pore-forming molecules are protein toxins that interact with mammalian cell membranes to promote lysis, deliver effectors, and modulate cellular homeostasis. Of the bacterial species capable of producing pore-forming toxic molecules, the Gram-positive pathogen Staphylococcus aureus is one of the most notorious. S. aureus can produce seven different pore-forming protein toxins, all of which are believed to play a unique role in promoting the ability of the organism to cause disease in humans and other mammals. The most diverse of these pore-forming toxins, in terms of both functional activity and global representation within S. aureus clinical isolates, are the bicomponent leucocidins. From the first description of their activity on host immune cells over 100 years ago to the detailed investigations of their biochemical function today, the leucocidins remain at the forefront of S. aureus pathogenesis research initiatives. Study of their mode of action is of immediate interest in the realm of therapeutic agent design as well as for studies of bacterial pathogenesis. This review provides an updated perspective on our understanding of the S. aureus leucocidins and their function, specificity, and potential as therapeutic targets.
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27
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Ma CY, Chang WE, Shi GY, Chang BY, Cheng SE, Shih YT, Wu HL. Recombinant Thrombomodulin Inhibits Lipopolysaccharide-Induced Inflammatory Response by Blocking the Functions of CD14. THE JOURNAL OF IMMUNOLOGY 2015; 194:1905-15. [DOI: 10.4049/jimmunol.1400923] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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28
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Nonprofessional phagocytic cell receptors involved in Staphylococcus aureus internalization. BIOMED RESEARCH INTERNATIONAL 2014; 2014:538546. [PMID: 24826382 PMCID: PMC4009297 DOI: 10.1155/2014/538546] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 03/21/2014] [Indexed: 12/22/2022]
Abstract
Staphylococcus aureus is a successful human and animal pathogen. The majority of infections caused by this pathogen are life threatening, primarily because S. aureus has developed multiple evasion strategies, possesses intracellular persistence for long periods, and targets the skin and soft tissues. Therefore, it is very important to understand the mechanisms employed by S. aureus to colonize and proliferate in these cells. The aim of this review is to describe the recent discoveries concerning the host receptors of nonprofessional phagocytes involved in S. aureus internalization. Most of the knowledge related to the interaction of S. aureus with its host cells has been described in professional phagocytic cells such as macrophages. Here, we showed that in nonprofessional phagocytes the α 5 β 1 integrin host receptor, chaperons, and the scavenger receptor CD36 are the main receptors employed during S. aureus internalization. The characterization and identification of new bacterial effectors and the host cell receptors involved will undoubtedly lead to new discoveries with beneficial purposes.
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Aman MJ, Adhikari RP. Staphylococcal bicomponent pore-forming toxins: targets for prophylaxis and immunotherapy. Toxins (Basel) 2014; 6:950-72. [PMID: 24599233 PMCID: PMC3968370 DOI: 10.3390/toxins6030950] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/22/2014] [Accepted: 02/26/2014] [Indexed: 01/09/2023] Open
Abstract
Staphylococccus aureus represents one of the most challenging human pathogens as well as a common colonizer of human skin and mucosal surfaces. S. aureus causes a wide range of diseases from skin and soft tissue infection (SSTI) to debilitating and life-threatening conditions such as osteomyelitis, endocarditis, and necrotizing pneumonia. The range of diseases reflects the remarkable diversity of the virulence factors produced by this pathogen, including surface antigens involved in the establishment of infection and a large number of toxins that mediate a vast array of cellular responses. The staphylococcal toxins are generally believed to have evolved to disarm the innate immune system, the first line of defense against this pathogen. This review focuses on recent advances on elucidating the biological functions of S. aureus bicomponent pore-forming toxins (BCPFTs) and their utility as targets for preventive and therapeutic intervention. These toxins are cytolytic to a variety of immune cells, primarily neutrophils, as well as cells with a critical barrier function. The lytic activity of BCPFTs towards immune cells implies a critical role in immune evasion, and a number of epidemiological studies and animal experiments relate these toxins to clinical disease, particularly SSTI and necrotizing pneumonia. Antibody-mediated neutralization of this lytic activity may provide a strategy for development of toxoid-based vaccines or immunotherapeutics for prevention or mitigation of clinical diseases. However, certain BCPFTs have been proposed to act as danger signals that may alert the immune system through an inflammatory response. The utility of a neutralizing vaccination strategy must be weighed against such immune-activating potential.
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Affiliation(s)
- M Javad Aman
- Integrated BioTherapeutics Inc., 21 Firstfield Rd., Gaithersburg, MD 20878, USA.
| | - Rajan P Adhikari
- Integrated BioTherapeutics Inc., 21 Firstfield Rd., Gaithersburg, MD 20878, USA.
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Yanai M, Rocha MA, Matolek AZ, Chintalacharuvu A, Taira Y, Chintalacharuvu K, Beenhouwer DO. Separately or combined, LukG/LukH is functionally unique compared to other staphylococcal bicomponent leukotoxins. PLoS One 2014; 9:e89308. [PMID: 24586678 PMCID: PMC3930693 DOI: 10.1371/journal.pone.0089308] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 01/20/2014] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen that elaborates several exotoxins. Among these are the bicomponent leukotoxins (BCLs), which include γ-hemolysin, Panton-Valentine leukocidin (PVL), and LukDE. The toxin components are classified as either F or S proteins, which are secreted individually and assemble on cell surfaces to form hetero-oligomeric pores resulting in lysis of PMNs and/or erythrocytes. F and S proteins of γ-hemolysin, PVL and LukDE have ∼ 70% sequence homology within the same class and several heterologous combinations of F and S members from these three bicomponent toxin groups are functional. Recently, an additional BCL pair, LukGH (also called LukAB) that has only 30% homology to γ-hemolysin, PVL and LukDE, has been characterized from S. aureus. Our results showed that LukGH was more cytotoxic to human PMNs than PVL. However, LukGH-induced calcium ion influx in PMNs was markedly attenuated and slower than that induced by PVL and other staphylococcal BCLs. In contrast to other heterologous BCL combinations, LukG in combination with heterologous S components, and LukH in combination with heterologous F components did not induce calcium ion entry or cell lysis in human PMNs or rabbit erythrocytes. Like PVL, LukGH induced IL-8 production by PMNs. While individual components LukG and LukH had no cytolytic or calcium influx activity, they each induced high levels of IL-8 transcription and secretion. IL-8 production induced by LukG or LukH was dependent on NF-κB. Therefore, our results indicate LukGH differs functionally from other staphylococcal BCLs.
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Affiliation(s)
- Machi Yanai
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
- Emergency and Critical Care, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan
| | - Miguel A. Rocha
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Anthony Z. Matolek
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Archana Chintalacharuvu
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Yasuhiko Taira
- Emergency and Critical Care, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan
| | - Koteswara Chintalacharuvu
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - David O. Beenhouwer
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail:
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Spaan AN, Henry T, van Rooijen WJM, Perret M, Badiou C, Aerts PC, Kemmink J, de Haas CJC, van Kessel KPM, Vandenesch F, Lina G, van Strijp JAG. The staphylococcal toxin Panton-Valentine Leukocidin targets human C5a receptors. Cell Host Microbe 2013; 13:584-594. [PMID: 23684309 DOI: 10.1016/j.chom.2013.04.006] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/15/2013] [Accepted: 04/09/2013] [Indexed: 12/14/2022]
Abstract
Panton-Valentine Leukocidin (PVL) is a staphylococcal bicomponent pore-forming toxin linked to severe invasive infections. Target-cell and species specificity of PVL are poorly understood, and the mechanism of action of this toxin in Staphylococcus aureus virulence is controversial. Here, we identify the human complement receptors C5aR and C5L2 as host targets of PVL, mediating both toxin binding and cytotoxicity. Expression and interspecies variations of the C5aR determine cell and species specificity of PVL. The C5aR binding PVL component, LukS-PV, is a potent inhibitor of C5a-induced immune cell activation. These findings provide insight into leukocidin function and staphylococcal virulence and offer directions for future investigations into individual susceptibility to severe staphylococcal disease.
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Affiliation(s)
- András N Spaan
- Medical Microbiology, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Thomas Henry
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France
| | | | - Magali Perret
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France
| | - Cédric Badiou
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France
| | - Piet C Aerts
- Medical Microbiology, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Johan Kemmink
- Medicinal Chemistry and Chemical Biology, Utrecht University, 3584CX Utrecht, The Netherlands
| | - Carla J C de Haas
- Medical Microbiology, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Kok P M van Kessel
- Medical Microbiology, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - François Vandenesch
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France; Hospices Civils de Lyon, 69007 Lyon, France
| | - Gérard Lina
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France; Hospices Civils de Lyon, 69007 Lyon, France
| | - Jos A G van Strijp
- Medical Microbiology, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands.
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DuMont AL, Torres VJ. Cell targeting by the Staphylococcus aureus pore-forming toxins: it's not just about lipids. Trends Microbiol 2013; 22:21-7. [PMID: 24231517 DOI: 10.1016/j.tim.2013.10.004] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 10/11/2013] [Accepted: 10/16/2013] [Indexed: 01/12/2023]
Abstract
Staphylococcus aureus employs numerous pore-forming cytotoxins to injure host immune cells and promote infection. Until recently, it was unclear how these cytotoxins targeted specific cell types for lysis. Membrane lipids were initially postulated to be cytotoxin receptor candidates. However, the cell-type specificity and species-dependent targeting of these toxins did not support lipids as sole receptors. The recent identification of proteinaceous receptors for several S. aureus cytotoxins now provides an explanation for the observed tropism. These findings also have important implications for the implementation of animal models to study S. aureus pathogenesis, and for the development of novel therapeutics.
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Affiliation(s)
- Ashley L DuMont
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
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Staphylococcus aureus LukAB cytotoxin kills human neutrophils by targeting the CD11b subunit of the integrin Mac-1. Proc Natl Acad Sci U S A 2013; 110:10794-9. [PMID: 23754403 DOI: 10.1073/pnas.1305121110] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Staphylococcus aureus causes diseases ranging from superficial wound infections to more invasive manifestations like osteomyelitis and endocarditis. The evasion of host phagocytes recruited to the site of infection is essential to the success of S. aureus as a pathogen. A single S. aureus strain can produce up to five different bicomponent pore-forming leukotoxins that lyse immune cells by forming pores in the cellular plasma membrane. Although these leukotoxins have been considered redundant due to their cytotoxic activity toward human neutrophils, each toxin displays varied species and cell-type specificities. This suggests that cellular factors may influence which cells each toxin targets. Here we describe the identification of CD11b, the α subunit of the αM/β2 integrin (CD11b/CD18), macrophage-1 antigen, or complement receptor 3, as a cellular receptor for leukocidin A/B (LukAB), an important toxin that contributes to S. aureus killing of human neutrophils. We demonstrate that CD11b renders human neutrophils susceptible to LukAB-mediated killing by purified LukAB as well as during S. aureus infection ex vivo. LukAB directly interacts with human CD11b by binding to the I domain, a property that determines the species specificity exhibited by this toxin. Identification of a LukAB cellular target has broad implications for the use of animal models to study the role of LukAB in S. aureus pathogenesis, explains the toxin's tropism toward human neutrophils and other phagocytes, and provides a cellular therapeutic target to block the effect of LukAB toward human neutrophils.
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Los FCO, Randis TM, Aroian RV, Ratner AJ. Role of pore-forming toxins in bacterial infectious diseases. Microbiol Mol Biol Rev 2013; 77:173-207. [PMID: 23699254 PMCID: PMC3668673 DOI: 10.1128/mmbr.00052-12] [Citation(s) in RCA: 293] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.
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Affiliation(s)
| | - Tara M. Randis
- Department of Pediatrics, Columbia University, New York, New York, USA
| | - Raffi V. Aroian
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, USA
| | - Adam J. Ratner
- Department of Pediatrics, Columbia University, New York, New York, USA
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Uhlemann AC, Kennedy AD, Martens C, Porcella SF, Deleo FR, Lowy FD. Toward an understanding of the evolution of Staphylococcus aureus strain USA300 during colonization in community households. Genome Biol Evol 2013; 4:1275-85. [PMID: 23104992 PMCID: PMC3542572 DOI: 10.1093/gbe/evs094] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus is a frequent cause of serious infections and also a human commensal. The emergence of community-associated methicillin-resistant S. aureus led to a dramatic increase in skin and soft tissue infections worldwide. This epidemic has been driven by a limited number of clones, such as USA300 in the United States. To better understand the extent of USA300 evolution and diversification within communities, we performed comparative whole-genome sequencing of three clinical and five colonizing USA300 isolates collected longitudinally from three unrelated households over a 15-month period. Phylogenetic analysis that incorporated additional geographically diverse USA300 isolates indicated that all but one likely arose from a common recent ancestor. Although limited genetic adaptation occurred over the study period, the greatest genetic heterogeneity occurred between isolates from different households and within one heavily colonized household. This diversity allowed for a more accurate tracking of interpersonal USA300 transmission. Sequencing of persisting USA300 isolates revealed mutations in genes involved in major aspects of S. aureus function: adhesion, cell wall biosynthesis, virulence, and carbohydrate metabolism. Genetic variations also included accumulation of multiple polymorphisms within select genes of two multigene operons, suggestive of small genome rearrangements rather than de novo single point mutations. Such rearrangements have been underappreciated in S. aureus and may represent novel means of strain variation. Subtle genetic changes may contribute to USA300 fitness and persistence. Elucidation of small genome rearrangements reveals a potentially new and intriguing mechanism of directed S. aureus genome diversification in environmental niches and during pathogen-host interactions.
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Affiliation(s)
- Anne-Catrin Uhlemann
- Division of Infectious Diseases, Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, NY, USA.
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LukS-PV induces mitochondrial-mediated apoptosis and G0/G1 cell cycle arrest in human acute myeloid leukemia THP-1 cells. Int J Biochem Cell Biol 2013; 45:1531-7. [PMID: 23702031 DOI: 10.1016/j.biocel.2013.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/11/2013] [Accepted: 05/13/2013] [Indexed: 11/20/2022]
Abstract
The S component (LukS-PV) is one of the two components of Panton-Valentine leukocidin (PVL), which is a pore-forming cytotoxin secreted by Staphylococcus aureus, with the ability to lyse leukocytes. In this study, LukS-PV had the ability to induce apoptosis in the human acute myeloid leukemia (AML) cell line THP-1. Therefore, we investigated the mechanisms of LukS-PV-induced apoptosis in THP-1 cells. THP-1 cells treated with LukS-PV, resulted in a significant inhibition of proliferation in a dose- and time-dependent manner, and induced G0/G1 arrest associated with an inhibition of cell cycle arrest regulatory protein (cyclin D1) in a dose- and time-dependent manner, as measured by flow cytometry (FCM). After 12h exposure to LukS-PV (1.00 μM), annexin V-EGFP/propidium iodide (PI) FCM revealed that 19.5±3.6% of THP-1 cells were apoptotic, and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) staining also revealed THP-1 cells were apoptotic. Chip analysis of 84 apoptosis-related genes demonstrated that 9 genes were up-regulated at least 2-fold and that 5 genes were down-regulated at least 2-fold in the treatment group when compared with levels in the control group. Western blotting reveled that the expression of caspase-8 increased significantly (approximately 4-fold). The levels of caspase-9, -3 and Bax increased significantly, and levels of Bcl-2 decreased rapidly with LukS-PV treatment. These data suggest that LukS-PV acts as an anti-leukemia agent and activates AML cell apoptosis via the mitochondrial pathway. Therefore, LukS-PV may be a multi-targeting drug candidate for the prevention and therapy of AML.
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Role of pore-forming toxins in neonatal sepsis. Clin Dev Immunol 2013; 2013:608456. [PMID: 23710203 PMCID: PMC3655490 DOI: 10.1155/2013/608456] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/27/2013] [Indexed: 11/17/2022]
Abstract
Protein toxins are important virulence factors contributing to neonatal sepsis. The major pathogens of neonatal sepsis, group B Streptococci, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, secrete toxins of different molecular nature, which are key for defining the disease. Amongst these toxins are pore-forming exotoxins that are expressed as soluble monomers prior to engagement of the target cell membrane with subsequent formation of an aqueous membrane pore. Membrane pore formation is not only a means for immediate lysis of the targeted cell but also a general mechanism that contributes to penetration of epithelial barriers and evasion of the immune system, thus creating survival niches for the pathogens. Pore-forming toxins, however, can also contribute to the induction of inflammation and hence to the manifestation of sepsis. Clearly, pore-forming toxins are not the sole factors that drive sepsis progression, but they often act in concert with other bacterial effectors, especially in the initial stages of neonatal sepsis manifestation.
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Genetic nature and virulence of community-associated methicillin-resistant Staphylococcus aureus. Biomedicine (Taipei) 2013. [DOI: 10.1016/j.biomed.2012.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Dai J, Pei D, Wang B, Kuang Y, Ren L, Cao K, Zuo B, Shao J, Li S, Jiang Z, Li H, Li M. A novel DNA vaccine expressing the Ag85A-HA2 fusion protein provides protection against influenza A virus and Staphylococcus aureus. Virol J 2013; 10:40. [PMID: 23369570 PMCID: PMC3598506 DOI: 10.1186/1743-422x-10-40] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 01/14/2013] [Indexed: 11/20/2022] Open
Abstract
Secondary pneumonia due to Staphylococcus aureus (S. aureus) causes significant morbidity and mortality. The aim of the research was designed a novel DNA vaccine encoding the Mycobacterium tuberculosis secreted antigen Ag85A fused with the influenza A virus (IAV) HA2 protein to provide protection against both influenza and secondary infection with S. aureus. The DNA vaccine vector efficiently expressed the encoded antigen in mammalian cells, as determined by RT-PCR, Western blotting and immunofluorescence analysis. Mice were immunized with the vaccine by intramuscular injection before challenge with IAV and S. aureus. The pulmonary and the splenocyte culture IFN-γ levels were significant higher in immunized mice than their respective controls. Although the antibody titer in the HI test was low, the sera of mice immunized with the novel vaccine vector were effective in neutralisation assay in vitro. The vaccine could reduce the loss of body weight in mice during IAV challenge. Both Western blotting and RT-PCR showed that the vaccine markedly enhanced toll like receptor 2 (TLR2) expression in splenocytes after the secondary infection with S. aureus. The survival rate of mice with high TLR2 expression (pEGFP/Ag85A-HA2 or iPR) was significantly increased compared with mice immunized with pEGFP/HA2 after challenge with S. aureus. However, the pulmonary IL-10 concentration and S. aureus titer were significantly decreased in immunized mice, and expression of TLR2 was increased after challenge with S. aureus. These results demonstrated that Ag85A could strengthen the immune response to IAV and S. aureus, and TLR2 was involved in the host response to S. aureus.
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Affiliation(s)
- Jun Dai
- Department of Microbiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan, PR China
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Ruan Y, Shen T, Wang Y, Hou M, Li J, Sun T. Antimicrobial peptide LL-37 attenuates LTA induced inflammatory effect in macrophages. Int Immunopharmacol 2013; 15:575-80. [PMID: 23375934 DOI: 10.1016/j.intimp.2013.01.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 01/07/2013] [Accepted: 01/15/2013] [Indexed: 01/01/2023]
Abstract
LL-37/hCAP-18, as the only human cathelicidin, plays an important role in inflammation. Lipoteichoic acid (LTA) is an important bacterial component of Staphylococcus aureus, which is one of the common human pathogens for severe respiratory infection with increasing morbidity in recent years. The present study is to investigate the role of LL-37 in LTA induced inflammatory reaction in macrophages. We examined TNF-α and IL-6 production after LL-37 treatment and discussed its signal transduction pathways such as p38MAPK and Akt activation in macrophages. The expression of pro-inflammatory cytokines was analyzed by quantitative real-time RT-PCR and enzyme-linked immunosorbent assay (ELISA). The LL-37 expression was determined by Western blot and immunofluorescence staining. The results showed that LL-37 was upregulated after LTA treatment. It could inhibit LTA induced p38MAPK and Akt phosphorylation and attenuate TNF-α and IL-6 production in macrophages in some specific concentration. These results suggest that LL-37 exerts an anti-inflammatory property and attenuates the pro-inflammatory cytokine release in macrophages.
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Affiliation(s)
- Yang Ruan
- Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
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Prince A. Innate Immune Responses in Ventilator-Associated Pneumonia. MUCOSAL IMMUNOLOGY OF ACUTE BACTERIAL PNEUMONIA 2013. [PMCID: PMC7121904 DOI: 10.1007/978-1-4614-5326-0_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Ventilator-associated pneumonia (VAP) is a common complication of mechanical ventilation, resulting in substantial morbidity, mortality, and health care cost. Early upper airway colonization by pathogenic bacteria and microaspiration are the primary pathogenic events leading to VAP. Patients at risk for VAP have defects in structural/mechanical defenses of the respiratory tract. In addition, critical illness, including sepsis, trauma, and postoperative states, is associated with profound defects in both innate and acquired antibacterial immunity, influencing antimicrobial effector functions of both leukocytes and structural/parenchymal cells. Factors present within the lung microenvironment, including alveolar stretch, cyclical atelectasis, changes in oxygen tension, and respiratory tract microbiota, substantially impact antibacterial host responses. Mechanisms accounting for dysregulated immune homeostasis are incompletely understood, but likely involve: (1) alterations in the balance of pro- and anti-inflammatory cytokines; (2) changes in pathogen recognition receptor and G-protein coupled receptor expression and downstream signaling cascades; and (3) dysregulated cell death responses. Antibiotics and preventive strategies are the mainstay of therapy in patients with VAP. However, novel approaches are needed to reverse immunological reprogramming that occurs during critical illness and/or mechanical ventilation, and to identify patients who are most likely to benefit from immunomodulatory therapy.
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Jover E, Tawk MY, Laventie BJ, Poulain B, Prévost G. Staphylococcal leukotoxins trigger free intracellular Ca(2+) rise in neurones, signalling through acidic stores and activation of store-operated channels. Cell Microbiol 2012; 15:742-58. [PMID: 23152983 PMCID: PMC3654557 DOI: 10.1111/cmi.12069] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/18/2012] [Accepted: 11/06/2012] [Indexed: 12/31/2022]
Abstract
Headache, muscle aches and chest pain of mild to medium intensity are among the most common clinical symptoms in moderate Staphylococcus aureus infections, with severe infections usually associated with worsening pain symptoms. These nociceptive responses of the body raise the question of how bacterial infection impinges on the nervous system. Does S. aureus, or its released virulence factors, act directly on neurones? To address this issue, we evaluated the potential effects on neurones of certain bi-component leukotoxins, which are virulent factors released by the bacterium. The activity of four different leukotoxins was verified by measuring the release of glutamate from rat cerebellar granular neurones. The bi-component γ-haemolysin HlgC/HlgB was the most potent leukotoxin, initiating transient rises in intracellular Ca2+ concentration in cerebellar neurones and in primary sensory neurones from dorsal root ganglia, as probed with the Fura-2 Ca2+ indicator dye. Using pharmacological antagonists of receptors and Ca2+ channels, the variations in intracellular Ca2+ concentration were found independent of the activation of voltage-operatedCa2+ channels or glutamate receptors. Drugs targeting Sarco-Endoplasmic Reticulum Ca2+-ATPase (SERCA) or H+-ATPase and antagonists of the store-operated Ca2+ entry complex blunted, or significantly reduced, the leukotoxin-induced elevation in intracellular Ca2+. Moreover, activation of the ADP-ribosyl cyclase CD38 was also required to initiate the release of Ca2+ from acidic stores. These findings suggest that, prior to forming a pore at the plasma membrane, leukotoxin HlgC/HlgB triggers a multistep process which initiates the release of Ca2+ from lysosomes, modifies the steady-state level of reticular Ca2+ stores and finally activates the Store-Operated Calcium Entry complex.
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Affiliation(s)
- Emmanuel Jover
- INCI - UPR-CNRS 3212, Neurotransmission et sécrétion neuroendocrine, 5, rue Blaise Pascal, F- 67084 Strasbourg cedex, France. jover@inci-cnrs
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Lipoteichoic acid from Staphylococcus aureus induces lung endothelial cell barrier dysfunction: role of reactive oxygen and nitrogen species. PLoS One 2012; 7:e49209. [PMID: 23166614 PMCID: PMC3499573 DOI: 10.1371/journal.pone.0049209] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 10/08/2012] [Indexed: 11/29/2022] Open
Abstract
Tunneled central venous catheters (TCVCs) are used for dialysis access in 82% of new hemodialysis patients and are rapidly colonized with Gram-positive organism (e.g. Staphylococcus aureus) biofilm, a source of recurrent infections and chronic inflammation. Lipoteichoic acid (LTA), a cell wall ribitol polymer from Gram-positive organisms, mediates inflammation through the Toll-like receptor 2 (TLR2). The effect of LTA on lung endothelial permeability is not known. We tested the hypothesis that LTA from Staphylococcus aureus induces alterations in the permeability of pulmonary microvessel endothelial monolayers (PMEM) that result from activation of TLR2 and are mediated by reactive oxygen/nitrogen species (RONS). The permeability of PMEM was assessed by the clearance rate of Evans blue-labeled albumin, the activation of the TLR2 pathway was assessed by Western blot, and the generation of RONS was measured by the fluorescence of oxidized dihydroethidium and a dichlorofluorescein derivative. Treatment with LTA or the TLR2 agonist Pam(3)CSK(4) induced significant increases in albumin permeability, IκBα phosphorylation, IRAK1 degradation, RONS generation, and endothelial nitric oxide synthase (eNOS) activation (as measured by the p-eNOSser1177:p-eNOSthr495 ratio). The effects on permeability and RONS were effectively prevented by co-administration of the superoxide scavenger Tiron, the peroxynitrite scavenger Urate, or the eNOS inhibitor L-NAME and these effects as well as eNOS activation were reduced or prevented by pretreatment with an IRAK1/4 inhibitor. The results indicate that the activation of TLR2 and the generation of ROS/RNS mediates LTA-induced barrier dysfunction in PMEM.
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Nishiyama A, Isobe H, Iwao Y, Takano T, Hung WC, Taneike I, Nakagawa S, Dohmae S, Iwakura N, Yamamoto T. Accumulation of staphylococcal Panton-Valentine leukocidin in the detergent-resistant membrane microdomains on the target cells is essential for its cytotoxicity. ACTA ACUST UNITED AC 2012; 66:343-52. [PMID: 22924956 DOI: 10.1111/j.1574-695x.2012.01027.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 07/24/2012] [Accepted: 07/27/2012] [Indexed: 12/23/2022]
Abstract
The mechanisms for the cytotoxicity of staphylococcal Panton-Valentine leukocidin (PVL), a pore-forming toxin consisting of LukS-PV and LukF-PV, in human immune cells are still unclear. Because LukS-PV binds to ganglioside GM1, a constituent of detergent-resistant membrane microdomains (DRMs) of the plasma membrane, the role of DRMs in PVL cytotoxicity was examined in human polymorphonuclear neutrophils (PMNs), monocytes, HL-60 cells, and THP-1 cells. PVL binding capacities in HL-60 and THP-1 cells were higher than those in PMNs and monocytes; however, the PVL concentration to obtain more than 80% cell lysis in HL-60 cells was 10 times higher than that in PMNs and PVL even at such concentration induced < 10% cell lysis in THP-1 cells. After incubation of PMNs with LukS-PV, more than 90% of LukS-PV bound to the detergent-soluble membranes. Subsequent incubation with LukF-PV at 4 °C induced the accumulation of more than 70% of PVL components and 170- to 220-kDa complex formation in DRMs in an actin-independent manner. However, only 30% of PVL was found, and complex formation was under detectable level in DRMs in HL-60 cells. PVL did not accumulate in DRMs in THP-1 cells. Our observations strongly indicate that PVL accumulation in DRMs is essential for PVL cytotoxicity.
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Affiliation(s)
- Akihito Nishiyama
- Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Holzinger D, Gieldon L, Mysore V, Nippe N, Taxman DJ, Duncan JA, Broglie PM, Marketon K, Austermann J, Vogl T, Foell D, Niemann S, Peters G, Roth J, Löffler B. Staphylococcus aureus Panton-Valentine leukocidin induces an inflammatory response in human phagocytes via the NLRP3 inflammasome. J Leukoc Biol 2012; 92:1069-81. [PMID: 22892107 DOI: 10.1189/jlb.0112014] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The Staphylococcus aureus pore-forming toxin PVL is most likely causative for life-threatening necrotizing infections, which are characterized by massive tissue inflammation and necrosis. Whereas the cytotoxic action of PVL on human neutrophils is already well established, the PVL effects on other sensitive cell types, such as monocytes and macrophages, are less clear. In this study, we used different types of human leukocytes (neutrophils, monocytes, macrophages, lymphocytes) to investigate cell-specific binding of PVL subunits and subsequent proinflammatory and cytotoxic effects. In all PVL-sensitive cells, we identified the binding of the subunit LukS-PV as the critical factor for PVL-induced cytotoxicity, which was followed by binding of LukF-PV. LukS-PV binds to monocytes, macrophages, and neutrophils but not to lymphocytes. Additionally, we showed that PVL binding to monocytes and macrophages leads to release of caspase-1-dependent proinflammatory cytokines IL-1β and IL-18. PVL activates the NLRP3 inflammasome, a signaling complex of myeloid cells that is involved in caspase-1-dependent IL-1β processing in response to pathogens and endogenous danger signals. Specific inhibition of this pathway at several steps significantly reduced inflammasome activation and subsequent pyronecrosis. Furthermore, we found that PAMPs and DAMPs derived from dying neutrophils can dramatically enhance this response by up-regulating pro-IL-1β in monocytes/macrophages. This study analyzes a specific host signaling pathway that mediates PVL-induced inflammation and cytotoxicity, which has high relevance for CA-MRSA-associated and PVL-mediated pathogenic processes, such as necrotizing infections.
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Affiliation(s)
- Dirk Holzinger
- Institute of Immunology, Department of General Pediatrics, University Children’s Hospital Münster, Münster, Germany
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Watkins RR, David MZ, Salata RA. Current concepts on the virulence mechanisms of meticillin-resistant Staphylococcus aureus. J Med Microbiol 2012; 61:1179-1193. [PMID: 22745137 DOI: 10.1099/jmm.0.043513-0] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Meticillin-resistant Staphylococcus aureus (MRSA) strains are prevalent bacterial pathogens that cause both health care and community-associated infections. Increasing resistance to commonly prescribed antibiotics has made MRSA a serious threat to public health throughout the world. The USA300 strain of MRSA has been responsible for an epidemic of community-associated infections in the US, mostly involving skin and soft tissue but also more serious invasive syndromes such as pneumonia, severe sepsis and endocarditis. MRSA strains are particularly serious and potentially lethal pathogens that possess virulence mechanisms including toxins, adhesins, enzymes and immunomodulators. One of these is Panton-Valentine leukocidin (PVL), a toxin associated with abscess formation and severe necrotizing pneumonia. Earlier studies suggested that PVL was a major virulence factor in community-associated MRSA infections. However, some recent data have not supported this association while others have, leading to controversy. Therefore, investigators continue to search for additional mechanisms of pathogenesis. In this review, we summarize the current understanding of the biological basis of MRSA virulence and explore future directions for research, including potential vaccines and antivirulence therapies under development that might allow clinicians to more successfully treat and prevent MRSA infections.
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Affiliation(s)
- Richard R Watkins
- Division of Infectious Diseases, Akron General Medical Center, Akron, OH 44302, USA
| | - Michael Z David
- Departments of Medicine and Health Studies, The University of Chicago, Chicago, IL, USA
| | - Robert A Salata
- Division of Infectious Diseases and HIV Medicine, University Hospitals Case Medical Center, Cleveland, OH, USA
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Immune-activating properties of Panton-Valentine leukocidin improve the outcome in a model of methicillin-resistant Staphylococcus aureus pneumonia. Infect Immun 2012; 80:2894-904. [PMID: 22665379 DOI: 10.1128/iai.06360-11] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Panton-Valentine leukocidin (PVL) is a cytotoxin expressed by many methicillin-resistant Staphylococcus aureus (MRSA) strains that cause community-acquired infections (CA-MRSA). Its role in virulence however, is controversial, with clinical data suggesting that PVL-producing strains may cause less severe disease in humans. PVL is capable of lysing human white blood cells, but at sublytic amounts, PVL can activate protective host immunity in the absence of cell damage. The concentration-dependent reactions it elicits from host cells could be the reason for seemingly contradictory results about PVL's role in virulence. We hypothesized that a key to understanding PVL's action on host cells and, possibly, outcomes from infection is the amount of toxin present, a hypothesis previously supported in studies using a low-inoculum skin infection model, where low levels of PVL augmented innate immune resistance to infection. Here, we present additional data supporting this hypothesis using a mouse model of MRSA pneumonia, wherein we found increased virulence of isogenic Δpvl strains and further confirmed PVL's capacity to activate proinflammatory responses from mouse and human neutrophils and pulmonary cells. Activation was measured as the production of phosphorylated p38 mitogen-activated protein kinase (MAPK) and proinflammatory cytokines interleukin-8 (IL-8) and KC (from human and mouse cells, respectively), as well as the release of antibacterial factors. Conversely, PVL lowered the levels of tumor necrosis factor alpha (TNF-α) produced in active pulmonary infection, while low doses induced apoptosis, suggesting that PVL also has the capacity to regulate inflammation. Our data indicate that, independent of its cytotoxic effects, PVL also plays an important and positive immunomodulatory role during MRSA infections.
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Graves SF, Kobayashi SD, Braughton KR, Whitney AR, Sturdevant DE, Rasmussen DL, Kirpotina LN, Quinn MT, DeLeo FR. Sublytic concentrations of Staphylococcus aureus Panton-Valentine leukocidin alter human PMN gene expression and enhance bactericidal capacity. J Leukoc Biol 2012; 92:361-74. [PMID: 22581932 DOI: 10.1189/jlb.1111575] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
CA-MRSA infections are often caused by strains encoding PVL, which can cause lysis of PMNs and other myeloid cells in vitro, a function considered widely as the primary means by which PVL might contribute to disease. However, at sublytic concentrations, PVL can function as a PMN agonist. To better understand this phenomenon, we investigated the ability of PVL to alter human PMN function. PMNs exposed to PVL had enhanced capacity to produce O(2)(-) in response to fMLF, but unlike priming by LPS, this response did not require TLR signal transduction. On the other hand, there was subcellular redistribution of NADPH oxidase components in PMNs following exposure of these cells to PVL--a finding consistent with priming. Importantly, PMNs primed with PVL had an enhanced ability to bind/ingest and kill Staphylococcus aureus. Priming of PMNs with other agonists, such as IL-8 or GM-CSF, altered the ability of PVL to cause formation of pores in the plasma membranes of these cells. Microarray analysis revealed significant changes in the human PMN transcriptome following exposure to PVL, including up-regulation of molecules that regulate the inflammatory response. Consistent with the microarray data, mediators of the inflammatory response were released from PMNs after stimulation with PVL. We conclude that exposure of human PMNs to sublytic concentrations of PVL elicits a proinflammatory response that is regulated in part at the level of gene expression. We propose that PVL-mediated priming of PMNs enhances the host innate immune response.
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Affiliation(s)
- Shawna F Graves
- Laboratory of Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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Ma X, Chang W, Zhang C, Zhou X, Yu F. Staphylococcal Panton-Valentine leukocidin induces pro-inflammatory cytokine production and nuclear factor-kappa B activation in neutrophils. PLoS One 2012; 7:e34970. [PMID: 22529963 PMCID: PMC3329533 DOI: 10.1371/journal.pone.0034970] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 03/08/2012] [Indexed: 12/21/2022] Open
Abstract
Panton-Valentine leukocidin (PVL) is a cytotoxin secreted by Staphylococcus aureus and associated with severe necrotizing infections. PVL targets polymorphonuclear leukocytes, especially neutrophils, which are the first line of defense against infections. Although PVL can induce neutrophil death by necrosis or apoptosis, the specific inflammatory responses of neutrophils to this toxin are unclear. In this study, both in vivo and in vitro studies demonstrated that recombinant PVL has an important cytotoxic role in human neutrophils, leading to apoptosis at low concentrations and necrosis at high concentrations. Recombinant PVL also increased the levels of pro-inflammatory cytokine secretion from neutrophils. The up-regulation of pro-inflammatory cytokines was due to nuclear factor-kappa B (NF-κB) activation induced by PVL. Moreover, blocking NF-κB inhibited the production of inflammatory cytokines. To test the role of neutrophil immune responses during the pathogenesis of PVL-induced acute lung injury, we used immunocompetent or neutropenic rabbits to develop a model of necrotizing pneumonia. Immunocompetent rabbits challenged with PVL demonstrated increased inflammation containing neutrophilic infiltrates. In addition, there were elevated levels of inflammatory cytokines (IL-6, IL-8, TNF-α and IL-10) and NF-κB in the lung homogenate. In contrast, the lung tissues from neutropenic rabbits contained mild or moderate inflammation, and the levels of inflammatory cytokines and NF-κB increased only slightly. Data from the current study support growing evidence that neutrophils play an important role in the pathogenesis of PVL-induced tissue injury and inflammation. PVL can stimulate neutrophils to release pro-inflammatory mediators, thereby causing an acute inflammatory response. The ability of PVL to induce inflammatory cytokine release may be associated with the activation of NF-κB or its pore-forming properties.
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Affiliation(s)
- Xiaoling Ma
- Department of Laboratory Medicine, Anhui Provincial Hospital, Anhui Medical University, Hefei, China.
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Toll-like receptors (TLRs) in innate immune defense against Staphylococcus aureus. Int J Artif Organs 2012; 34:799-810. [PMID: 22094559 DOI: 10.5301/ijao.5000030] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2011] [Indexed: 01/01/2023]
Abstract
Toll-like receptors (TLRs) are the most important class of innate pattern recognition receptors (PRRs) by which host immune and non-immune cells are able to recognize pathogen-associated molecular patterns (PAMPs). Most mammalian species have 10 to 15 types of TLRs. TLRs are believed to function as homo- or hetero-dimers. TLR2, which plays a crucial role in recognizing PAMPs from Staphylococcus aureus, forms heterodimers with TLR1 or TLR6 and each dimer has a different ligand specificity. Staphylococcal lipoproteins, Panton-Valentine toxin and Phenol Soluble Modulins have been identified as potent TLR2 ligands. Conversely, the ligand function attributed to peptidoglycan and LTA remains controversial. TLR2 uses a MyD88-dependent signaling pathway that results in NF-kB translocation into the nucleus and activation of the expression of pro-inflammatory cytokine genes. Recognition rouses both an inflammatory response, culminating in the phagocytosis of bacteria, and an adaptive immune response, with the presentation of resulting bacterial compounds to T cells. Here, recent advances on the recognition of S. aureus by TLRs are presented and discussed, as well as the new therapeutic opportunities deriving from this new knowledge.
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