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Khayata M, Grimm RA, Griffin BP, Xu B. Prevalence, Characteristics, and Outcomes of Infective Endocarditis Readmissions in Patients With Variables Associated With Liver Disease in the United States. Angiology 2024:33197241227502. [PMID: 38215273 DOI: 10.1177/00033197241227502] [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: 01/14/2024]
Abstract
Infective endocarditis (IE) is common in patients with liver disease. Outcomes of IE in patients with liver disease are limited. We aimed to investigate IE outcomes in patients with variables associated with liver disease in the USA. We used the 2017 National Readmission Database to identify index admission of adults with IE, based on the International Classification of Disease, 10th revision codes. The primary outcome was 30-day readmission. Secondary outcomes were mortality and predictors of hospital readmission. We identified 40,413 IE admissions. Patients who were readmitted were more likely to have a history of HCV (19.4 vs 12.3%, P < .001), hyponatremia (25 vs 21%, P < .001), and thrombocytopenia (20.3 vs 16.3%, P < .001). After adjusting for age, hypertension, heart failure, diabetes mellitus, and end stage renal disease, hyponatremia (odds ratio (OR) 1.25; 95% confidence intervals [CI]: 1.17-1.35; P < .001) and thrombocytopenia (OR 1.16; 95% CI: 1.08-1.24; P < .001) correlated with higher odds of 30-day readmission. Mortality was higher among patients with hyponatremia (29 vs 22%, P < .001), thrombocytopenia (29 vs 17%, P < .001), coagulopathy (12 vs 5%, P < .001), cirrhosis (6 vs 4%, P < .001), ascites (7 vs 3%, P < .001), liver failure (18 vs 3%, P < .001), and portal hypertension (3 vs 1.5%, P < .001).
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Affiliation(s)
- Mohamed Khayata
- Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydnell and Arnold Family Heart, Vascular, and Thoracic Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Richard A Grimm
- Section of Cardiovascular Imaging, Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydnell and Arnold Family Heart, Vascular, and Thoracic Institute, Cleveland, OH, USA
| | - Brian P Griffin
- Section of Cardiovascular Imaging, Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydnell and Arnold Family Heart, Vascular, and Thoracic Institute, Cleveland, OH, USA
| | - Bo Xu
- Section of Cardiovascular Imaging, Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydnell and Arnold Family Heart, Vascular, and Thoracic Institute, Cleveland, OH, USA
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2
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Bhattacharya M, Horswill AR. The role of human extracellular matrix proteins in defining Staphylococcus aureus biofilm infections. FEMS Microbiol Rev 2024; 48:fuae002. [PMID: 38337187 PMCID: PMC10873506 DOI: 10.1093/femsre/fuae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 01/26/2024] [Accepted: 02/07/2024] [Indexed: 02/12/2024] Open
Abstract
Twenty to forty one percent of the world's population is either transiently or permanently colonized by the Gram-positive bacterium, Staphylococcus aureus. In 2017, the CDC designated methicillin-resistant S. aureus (MRSA) as a serious threat, reporting ∼300 000 cases of MRSA-associated hospitalizations annually, resulting in over 19 000 deaths, surpassing that of HIV in the USA. S. aureus is a proficient biofilm-forming organism that rapidly acquires resistance to antibiotics, most commonly methicillin (MRSA). This review focuses on a large group of (>30) S. aureus adhesins, either surface-associated or secreted that are designed to specifically bind to 15 or more of the proteins that form key components of the human extracellular matrix (hECM). Importantly, this includes hECM proteins that are pivotal to the homeostasis of almost every tissue environment [collagen (skin), proteoglycans (lung), hemoglobin (blood), elastin, laminin, fibrinogen, fibronectin, and fibrin (multiple organs)]. These adhesins offer S. aureus the potential to establish an infection in every sterile tissue niche. These infections often endure repeated immune onslaught, developing into chronic, biofilm-associated conditions that are tolerant to ∼1000 times the clinically prescribed dose of antibiotics. Depending on the infection and the immune response, this allows S. aureus to seamlessly transition from colonizer to pathogen by subtly manipulating the host against itself while providing the time and stealth that it requires to establish and persist as a biofilm. This is a comprehensive discussion of the interaction between S. aureus biofilms and the hECM. We provide particular focus on the role of these interactions in pathogenesis and, consequently, the clinical implications for the prevention and treatment of S. aureus biofilm infections.
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Affiliation(s)
- Mohini Bhattacharya
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, United States
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, United States
- Department of Veterans Affairs, Eastern Colorado Health Care System, Aurora, CO 80045, United States
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3
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Staphylococcus aureus increases platelet reactivity in patients with infective endocarditis. Sci Rep 2022; 12:12933. [PMID: 35902612 PMCID: PMC9334290 DOI: 10.1038/s41598-022-16681-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 07/13/2022] [Indexed: 01/30/2023] Open
Abstract
Thromboembolism is frequent in infective endocarditis (IE). However, the optimal antithrombotic regimen in IE is unknown. Staphylococcus aureus (SA) is the leading cause of IE. First studies emphasize increased platelet reactivity by SA. In this pilot study, we hypothesized that platelet reactivity is increased in patients with SA− IE, which could be abrogated by antiplatelet medication. We conducted a prospective, observatory, single-center cohort study in 114 patients with IE, with four cohorts: (1) SA coagulase positive IE without aspirin (ASA) medication, (2) coagulase negative IE without ASA, (3) SA coagulase positive IE with ASA, (4) coagulase negative IE with ASA. Platelet function was measured by Multiplate electrode aggregometry, blood clotting by ROTEM thromboelastometry. Bleeding events were assessed according to TIMI classification. In ASA-naïve patients, aggregation with ADP was increased with coag. pos. IE (coagulase negative: 39.47 ± 4.13 AUC vs. coagulase positive: 59.46 ± 8.19 AUC, p = 0.0219). This was abrogated with ASA medication (coagulase negative: 42.4 ± 4.67 AUC vs. coagulase positive: 45.11 ± 6.063 AUC p = 0.7824). Aspirin did not increase bleeding in SA positive patients. However, in SA negative patients with aspirin, red blood cell transfusions were enhanced. SA coagulase positive IE is associated with increased platelet reactivity. This could be abrogated by aspirin without increased bleeding risk. The results of this pilot study suggest that ASA might be beneficial in SA coagulase positive IE. This needs to be confirmed in clinical trials.
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4
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Winskel-Wood B, Padula MP, Marks DC, Johnson L. Cold storage alters the immune characteristics of platelets and potentiates bacterial-induced aggregation. Vox Sang 2022; 117:1006-1015. [PMID: 35579630 DOI: 10.1111/vox.13293] [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: 03/09/2022] [Revised: 04/13/2022] [Accepted: 04/20/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVES Cold-stored platelets are currently under clinical evaluation and have been approved for limited clinical use in the United States. Most studies have focused on the haemostatic functionality of cold-stored platelets; however, limited information is available examining changes to their immune function. MATERIALS AND METHODS Two buffy-coat-derived platelet components were combined and split into two treatment arms: room temperature (RT)-stored (20-24°C) or refrigerated (cold-stored, 2-6°C). The concentration of select soluble factors was measured in the supernatant using commercial ELISA kits. The abundance of surface receptors associated with immunological function was assessed by flow cytometry. Platelet aggregation was assessed in response to Escherichia coli and Staphylococcus aureus, in the presence and absence of RGDS (blocks active conformation of integrin α2 β3 ). RESULTS Cold-stored platelet components contained a lower supernatant concentration of C3a, RANTES and PF4. The abundance of surface-bound P-selectin and integrin α2 β3 in the activated conformation increased during cold storage. In comparison, the abundance of CD86, CD44, ICAM-2, CD40, TLR1, TLR2, TLR4, TLR3, TLR7 and TLR9 was lower on the surface membrane of cold-stored platelets compared to RT-stored components. Cold-stored platelets exhibited an increased responsiveness to E. coli- and S. aureus-induced aggregation compared to RT-stored platelets. Inhibition of the active conformation of integrin α2 β3 using RGDS reduced the potentiation of bacterial-induced aggregation in cold-stored platelets. CONCLUSION Our data highlight that cold storage changes the in vitro immune characteristics of platelets, including their sensitivity to bacterial-induced aggregation. Changes in these immune characteristics may have clinical implications post transfusion.
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Affiliation(s)
- Ben Winskel-Wood
- Research and Development, Australian Red Cross Lifeblood, Alexandria, New South Wales, Australia.,School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Matthew P Padula
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Denese C Marks
- Research and Development, Australian Red Cross Lifeblood, Alexandria, New South Wales, Australia.,Sydney Medical School, The University of Sydney, Camperdown, New South Wales, Australia
| | - Lacey Johnson
- Research and Development, Australian Red Cross Lifeblood, Alexandria, New South Wales, Australia.,School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
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5
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Schwarz C, Töre Y, Hoesker V, Ameling S, Grün K, Völker U, Schulze PC, Franz M, Faber C, Schaumburg F, Niemann S, Hoerr V. Host-pathogen interactions of clinical S. aureus isolates to induce infective endocarditis. Virulence 2021; 12:2073-2087. [PMID: 34490828 PMCID: PMC8425731 DOI: 10.1080/21505594.2021.1960107] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
To evaluate potential pathomechanisms in the induction of infective endocarditis (IE), 34 Staphylococcus aureus (S. aureus) isolates, collected from patients with S. aureus endocarditis and from healthy individuals were investigated both in vitro and in vivo. S. aureus isolates were tested in vitro for their cytotoxicity, invasion and the association with platelets. Virulence factor expression profiles and cellular response were additionally investigated and tested for correlation with the ability of S. aureus to induce vegetations on the aortic valves in vivo. In an animal model of IE valvular conspicuity was assessed by in vivo magnetic resonance imaging at 9.4 T, histology and enrichment gene expression analysis. All S. aureus isolates tested in vivo caused a reliable infection and inflammation of the aortic valves, but could not be differentiated and categorized according to the measured in vitro virulence profiles and cytotoxicity. Results from in vitro assays did not correlate with the severity of IE. However, the isolates differed substantially in the activation and inhibition of pathways connected to the extracellular matrix and inflammatory response. Thus, comprehensive approaches of host-pathogen interactions and corresponding immune pathways are needed for the evaluation of the pathogenic capacity of bacteria. An improved understanding of the interaction between virulence factors and immune response in S. aureus infective endocarditis would offer novel possibilities for the development of therapeutic strategies and specific diagnostic imaging markers.
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Affiliation(s)
- Christian Schwarz
- Translational Research Imaging Center, Clinic for Radiology, University Hospital Muenster, Muenster, Germany
| | - Yasemin Töre
- Translational Research Imaging Center, Clinic for Radiology, University Hospital Muenster, Muenster, Germany
| | - Vanessa Hoesker
- Translational Research Imaging Center, Clinic for Radiology, University Hospital Muenster, Muenster, Germany
| | - Sabine Ameling
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Greifswald, Greifswald, Germany
| | - Katja Grün
- Department of Internal Medicine I, Jena University Hospital, Jena, Germany
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Greifswald, Greifswald, Germany
| | | | - Marcus Franz
- Department of Internal Medicine I, Jena University Hospital, Jena, Germany
| | - Cornelius Faber
- Translational Research Imaging Center, Clinic for Radiology, University Hospital Muenster, Muenster, Germany
| | - Frieder Schaumburg
- Institute of Medical Microbiology, University Hospital Muenster, Muenster, Germany
| | - Silke Niemann
- Institute of Medical Microbiology, University Hospital Muenster, Muenster, Germany
| | - Verena Hoerr
- Translational Research Imaging Center, Clinic for Radiology, University Hospital Muenster, Muenster, Germany.,Institute of Medical Microbiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany.,Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
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6
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Lerche CJ, Schwartz F, Theut M, Fosbøl EL, Iversen K, Bundgaard H, Høiby N, Moser C. Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome. Front Cell Dev Biol 2021; 9:643335. [PMID: 34222225 PMCID: PMC8249808 DOI: 10.3389/fcell.2021.643335] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/04/2021] [Indexed: 12/13/2022] Open
Abstract
Infective endocarditis (IE) is a life-threatening infective disease with increasing incidence worldwide. From early on, in the antibiotic era, it was recognized that high-dose and long-term antibiotic therapy was correlated to improved outcome. In addition, for several of the common microbial IE etiologies, the use of combination antibiotic therapy further improves outcome. IE vegetations on affected heart valves from patients and experimental animal models resemble biofilm infections. Besides the recalcitrant nature of IE, the microorganisms often present in an aggregated form, and gradients of bacterial activity in the vegetations can be observed. Even after appropriate antibiotic therapy, such microbial formations can often be identified in surgically removed, infected heart valves. Therefore, persistent or recurrent cases of IE, after apparent initial infection control, can be related to biofilm formation in the heart valve vegetations. On this background, the present review will describe potentially novel non-antibiotic, antimicrobial approaches in IE, with special focus on anti-thrombotic strategies and hyperbaric oxygen therapy targeting the biofilm formation of the infected heart valves caused by Staphylococcus aureus. The format is translational from preclinical models to actual clinical treatment strategies.
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Affiliation(s)
- Christian Johann Lerche
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Franziska Schwartz
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Marie Theut
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Emil Loldrup Fosbøl
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Kasper Iversen
- Department of Cardiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.,Department of Emergency Medicine, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
| | - Henning Bundgaard
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.,Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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7
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Döhrmann M, Makhoul S, Gross K, Krause M, Pillitteri D, von Auer C, Walter U, Lutz J, Volf I, Kehrel BE, Jurk K. CD36-fibrin interaction propagates FXI-dependent thrombin generation of human platelets. FASEB J 2020; 34:9337-9357. [PMID: 32463151 DOI: 10.1096/fj.201903189r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/11/2020] [Accepted: 04/28/2020] [Indexed: 12/27/2022]
Abstract
Thrombin converts fibrinogen to fibrin and activates blood and vascular cells in thrombo-inflammatory diseases. Platelets are amplifiers of thrombin formation when activated by leukocyte- and vascular cell-derived thrombin. CD36 on platelets acts as sensitizer for molecules with damage-associated molecular patterns, thereby increasing platelet reactivity. Here, we investigated the role of CD36 in thrombin-generation on human platelets, including selected patients with advanced chronic kidney disease (CKD). Platelets deficient in CD36 or blocked by anti-CD36 antibody FA6.152 showed impaired thrombin generation triggered by thrombin in calibrated automated thrombography. Using platelets with congenital function defects, blocking antibodies, pharmacological inhibitors, and factor-depleted plasma, CD36-sensitive thrombin generation was dependent on FXI, fibrin, and platelet signaling via GPIbα and SFKs. CD36-deficiency or blocking suppressed thrombin-induced platelet αIIbβ3 activation, granule exocytosis, binding of adhesion proteins and FV, FVIII, FIX, FX, but not anionic phospholipid exposure determined by flow cytometry. CD36 ligated specifically soluble fibrin, which recruited distinct coagulation factors via thiols. Selected patients with CKD showed elevated soluble fibrin plasma levels and enhanced thrombin-induced thrombin generation, which was normalized by CD36 blocking. Thus, CD36 is an important amplifier of platelet-dependent thrombin generation when exposure of anionic phospholipids is limited. This pathway might contribute to hypercoagulability in CKD.
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Affiliation(s)
- Mareike Döhrmann
- Center for Thrombosis and Hemostasis (CTH), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Stephanie Makhoul
- Center for Thrombosis and Hemostasis (CTH), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Kathrin Gross
- Center for Thrombosis and Hemostasis (CTH), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Manuela Krause
- Deutsche Klinik für Diagnostik HELIOS Klinik, Wiesbaden, Germany
| | | | - Charis von Auer
- Third Department of Medicine, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Ulrich Walter
- Center for Thrombosis and Hemostasis (CTH), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Jens Lutz
- Section of Nephrology, I. Department of Medicine, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany.,Medical Clinic, Section of Nephrology and Infectious Diseases, Gemeinschaftsklinikum Mittelrhein, Koblenz, Germany
| | - Ivo Volf
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Beate E Kehrel
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Muenster, Muenster, Germany
| | - Kerstin Jurk
- Center for Thrombosis and Hemostasis (CTH), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany.,Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Muenster, Muenster, Germany
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8
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Abstract
The main strategies used by pathogenic bacteria to infect eukaryotic tissue include their adherence to cells and the extracellular matrix (ECM), the subsequent colonization and invasion as well as the evasion of immune defences. A variety of structurally and functionally characterized adhesins and binding proteins of gram-positive bacteria facilitate these processes by specifically recognizing and interacting with various components of the host ECM, including different collagens, fibronectin and other macromolecules. The ECM affects the cellular physiology of our body and is critical for adhesion, migration, proliferation, and differentiation of many host cell types, but also provides the support for infiltrating pathogens, particularly under conditions of injury and trauma. Moreover, microbial binding to a variety of adhesive components in host tissue fluids leads to structural and/or functional alterations of host proteins and to the activation of cellular mechanisms that influence tissue and cell invasion of pathogens. Since the diverse interactions of gram-positive bacteria with the ECM represent important pathogenicity mechanisms, their characterization not only allows a better understanding of microbial invasion but also provides clues for the design of novel therapeutic strategies to manage infectious diseases.
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9
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The Role of Platelets in Antimicrobial Host Defense. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00029-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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10
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Binsker U, Kohler TP, Hammerschmidt S. Contribution of Human Thrombospondin-1 to the Pathogenesis of Gram-Positive Bacteria. J Innate Immun 2019; 11:303-315. [PMID: 30814475 PMCID: PMC6738282 DOI: 10.1159/000496033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 12/03/2018] [Indexed: 12/12/2022] Open
Abstract
A successful colonization of different compartments of the human host requires multifactorial contacts between bacterial surface proteins and host factors. Extracellular matrix proteins and matricellular proteins such as thrombospondin-1 play a pivotal role as adhesive substrates to ensure a strong interaction with pathobionts like the Gram-positive Streptococcus pneumoniae and Staphylococcus aureus. The human glycoprotein thrombospondin-1 is a component of the extracellular matrix and is highly abundant in the bloodstream during bacteremia. Human platelets secrete thrombospondin-1, which is then acquired by invading pathogens to facilitate colonization and immune evasion. Gram-positive bacteria express a broad spectrum of surface-exposed proteins, some of which also recognize thrombospondin-1. This review highlights the importance of thrombospondin-1 as an adhesion substrate to facilitate colonization, and we summarize the variety of thrombospondin-1-binding proteins of S. pneumoniae and S. aureus.
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Affiliation(s)
- Ulrike Binsker
- Center for Functional Genomics of Microbes, Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Greifswald University, Greifswald, Germany
- Department of Microbiology, NYU Langone Health, Alexandria Center for the Life Sciences, New York City, New York, USA
| | - Thomas P Kohler
- Center for Functional Genomics of Microbes, Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Greifswald University, Greifswald, Germany
| | - Sven Hammerschmidt
- Center for Functional Genomics of Microbes, Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Greifswald University, Greifswald, Germany,
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11
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Palankar R, Kohler TP, Krauel K, Wesche J, Hammerschmidt S, Greinacher A. Platelets kill bacteria by bridging innate and adaptive immunity via platelet factor 4 and FcγRIIA. J Thromb Haemost 2018; 16:1187-1197. [PMID: 29350833 DOI: 10.1111/jth.13955] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Indexed: 12/15/2022]
Abstract
Essentials Human platelets specifically interact with IgG opsonized bacteria through FcγRIIA. Platelet factor 4 (PF4) binds to polyanions (P) and undergoes a conformational change. Anti-PF4/P IgG opsonizes PF4-coated Gram-positive and Gram-negative bacteria. Platelets specifically kill E.coli opsonized with PF4 and human anti-PF4/P IgG. SUMMARY Background Activated platelets release the chemokine platelet factor 4 (PF4) stored in their granules. PF4 binds to polyanions (P) on bacteria, undergoes a conformational change and exposes neoepitopes. These neoepitopes induce production of anti-PF4/P antibodies. As PF4 binds to a variety of bacteria, anti-PF4/P IgG can bind and opsonize several bacterial species. Objective Here we investigated whether platelets are able to kill bacteria directly after recognizing anti-PF4/P IgG opsonized bacteria in the presence of PF4 via their FcγRIIA. Methods Using platelet-bacteria suspension co-culture experiments and micropatterns with immobilized viable bacteria, in combination with pharmacological inhibitors and human anti- PF4/P IgG we analyzed the role of platelet-mediated killing of bacteria. Results In the presence of PF4, human anti-PF4/P IgG and platelets, E. coli killing (> 50%) with colony forming units (CFU mL-1 ) 0.71 × 104 ± 0.19 was observed compared with controls incubated only with anti-PF4/P IgG (CFU mL-1 3.4 × 104 ± 0.38). Blocking of platelet FcγRIIA using mAb IV.3 (CFU mL-1 2.5 × 104 ± 0.45), or integrin αIIbβ3 (CFU mL-1 2.26 × 104 ± 0.31), or disruption of cytoskeletal functions (CFU mL-1 2.7 × 104 ± 0.4) markedly reduced E. coli killing by this mechanism. Our observation of E. coli killing by platelets on micropatterned arrays is compatible with the model that platelets kill bacteria by covering them, actively concentrating them into the area under their granulomere and then releasing antimicrobial substances of platelet α-granules site directed towards bacteria. Conclusion These findings collectively indicate that by bridging of innate and adaptive immune mechanisms, platelets and anti-PF4/polyanion antibodies cooperate in an antibacterial host response.
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Affiliation(s)
- R Palankar
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - T P Kohler
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - K Krauel
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - J Wesche
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - S Hammerschmidt
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - A Greinacher
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
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12
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Liesenborghs L, Verhamme P, Vanassche T. Staphylococcus aureus, master manipulator of the human hemostatic system. J Thromb Haemost 2018; 16:441-454. [PMID: 29251820 DOI: 10.1111/jth.13928] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Indexed: 12/15/2022]
Abstract
The coagulation system does not only offer protection against bleeding, but also aids in our defense against invading microorganisms. The hemostatic system and innate immunity are strongly entangled, which explains why so many infections are complicated by either bleeding or thrombosis. Staphylococcus aureus (S. aureus), currently the most deadly infectious agent in the developed world, causes devastating intravascular infections such as sepsis and infective endocarditis. During these infections S. aureus comes in close contact with the host hemostatic system and proves to be a master in manipulating coagulation. The coagulases of S. aureus directly induce coagulation by activating prothrombin. S. aureus also manipulates fibrinolysis by triggering plasminogen activation via staphylokinase. Furthermore, S. aureus binds and activates platelets and interacts with key coagulation proteins such as fibrin(ogen), fibronectin and von Willebrand factor. By manipulating the coagulation system S. aureus gains a significant advantage over the host defense mechanisms. Studying the interplay between S. aureus and the hemostatic system can therefore lead to new innovative therapies for battling S. aureus infections.
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Affiliation(s)
- L Liesenborghs
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KULeuven - University Hospitals Leuven, Leuven, Belgium
| | - P Verhamme
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KULeuven - University Hospitals Leuven, Leuven, Belgium
| | - T Vanassche
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KULeuven - University Hospitals Leuven, Leuven, Belgium
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13
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Hoerr V, Franz M, Pletz MW, Diab M, Niemann S, Faber C, Doenst T, Schulze PC, Deinhardt-Emmer S, Löffler B. S. aureus endocarditis: Clinical aspects and experimental approaches. Int J Med Microbiol 2018. [PMID: 29526448 DOI: 10.1016/j.ijmm.2018.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Infective endocarditis (IE) is a life-threatening disease, caused by septic vegetations and inflammatory foci on the surface of the endothelium and the valves. Due to its complex and often indecisive presentation the mortality rate is still about 30%. Most frequently bacterial microorganisms entering the bloodstream are the underlying origin of the intracardiac infection. While the disease was primarily restricted to younger patients suffering from rheumatic heart streptococci infections, new at risk categories for Staphylococcus (S.) aureus infections arose over the last years. Rising patient age, increasing drug resistance, intensive treatment conditions such as renal hemodialysis, immunosuppression and long term indwelling central venous catheters but also the application of modern cardiac device implants and valve prosthesis have led to emerging incidences of S. aureus IE in health care settings and community. The aetiologic change has impact on the pathophysiology of IE, the clinical presentation and the overall patient management. Despite intensive research on appropriate in vitro and in vivo models of IE and gained knowledge about the fundamental mechanisms in the formation of bacterial vegetations and extracardiac complications, improved understanding of relevant bacterial virulence factors and triggered host immune responses is required to help developing novel antipathogenic treatment strategies and pathogen specific diagnostic markers. In this review, we summarize and discuss the two main areas affected by the changing patient demographics and provide first, recent knowledge about the pathogenic strategies of S. aureus in the induction of IE, including available experimental models of IE used to study host-pathogen interactions and diagnostic and therapeutic targets. In a second focus we present diagnostic (imaging) regimens for patients with S. aureus IE according to current guidelines as well as treatment strategies and surgical recommendations.
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Affiliation(s)
- V Hoerr
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany.
| | - M Franz
- Department of Internal Medicine I, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - M W Pletz
- Institute for Infectious Diseases and Infection Control, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - M Diab
- Department of Cardiothoracic Surgery, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - S Niemann
- Institute of Medical Microbiology, University Hospital Münster, Domagkstr. 10, 48149 Münster, Germany
| | - C Faber
- Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A16, 48149 Münster, Germany
| | - T Doenst
- Department of Cardiothoracic Surgery, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - P C Schulze
- Department of Internal Medicine I, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - S Deinhardt-Emmer
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - B Löffler
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
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14
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Arshad N, Mehreen A, Liaqat I, Arshad M, Afrasiab H. In vivo screening and evaluation of four herbs against MRSA infections. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017; 17:498. [PMID: 29169369 PMCID: PMC5701375 DOI: 10.1186/s12906-017-2001-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/13/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND Recently, we reported high in vitro antibacterial efficacy of Althaea officinalis, Ziziphus jujuba, Cordia latifolia and Thymus vulgaris out of a total 21 plants against wide range of bacteria including MRSA. This study was therefore, designed to confirm efficacy of these four herbs against MRSA in an animal model. METHODS A pilot study was conducted to establish the dose of S. aureus (KY698020) required to induce clinical infection. Afterword, in main trial, efficacy of aforementioned plant extracts on the course of sore throat was checked by evaluating general health, gross lesion score, bacterial load and hematology in mice. RESULTS Pilot study revealed that 40 μl dose of 107 CFU/ml could induce infection which persist upto 08 days post infection. Mice treated with T. vulgaris and Z. jujuba showed reduction in gross lesion score of both heart and lungs. Treatment with only some plants could significantly decrease bacterial load of throat (T. vulgaris) heart, blood and joint (C. latifolia, and T. vulagris). Hematological indicators confirmed in vivo control of MRSA infection in all treatment groups except A. officinalis. CONCLUSION This is first report confirming in vivo anti-MRSA potential of C. latifolia and T. vulgaris and highlight the need to explore bioactive constituents of these plants. Moreover, previously reported in vitro antibacterial efficiency of A. officinalis could not be validated in current study.
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Affiliation(s)
- Najma Arshad
- Department of Zoology, University of the Punjab, Lahore, Punjab, Pakistan.
| | - Arifa Mehreen
- Department of Zoology, University of the Punjab, Lahore, Punjab, Pakistan
| | - Iram Liaqat
- Department of Zoology, Government College University, Lahore, Punjab, Pakistan
| | - Muhammad Arshad
- Department of Zoology, University of Education, Lahore, Punjab, Pakistan
| | - Humera Afrasiab
- Department of Botany, University of the Punjab, Lahore, Punjab, Pakistan
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15
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Bertling A, Brodde MF, Visser M, Treffon J, Fennen M, Fender AC, Kelsch R, Kehrel BE. Components in Plasma-Derived Factor VIII, But Not in Recombinant Factor VIII Downregulate Anti-Inflammatory Surface Marker CD163 in Human Macrophages through Release of CXCL4 (Platelet Factor 4). Transfus Med Hemother 2017; 44:351-357. [PMID: 29070980 DOI: 10.1159/000472157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 03/22/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hemarthrosis, or bleeding into the joints, is a hallmark of hemophilia. Heme triggers oxidative stress, inflammation, and destruction of cartilage and bone. The haptoglobin-CD163-heme oxygenase-1 (HO-1) pathway circumvents heme toxicity through enzymatic degradation of heme and transcription of antioxidant genes. Plasma-derived factor concentrates contain many proteins that might impact on cellular pathways in joints, blood, and vessels. METHODS Activation of platelets from healthy volunteers was assessed by flow cytometry analysis of fibrinogen binding and CD62P expression. Platelet CXCL4 release was measured by ELISA. Human peripheral blood mononuclear cells were exposed to CXCL4 or platelet supernatants (untreated or pre-stimulated with factor VIII (FVIII) products) during their differentiation to macrophages and analyzed for CD163 expression. Some macrophage cultures were additionally incubated with autologous hemoglobin for 18 h for analysis of HO-1 expression. RESULTS Platelet CXCL4 release was increased by all 8 tested plasma-derived FVIII products but not the 3 recombinant products. Macrophages exposed to supernatant from platelets treated with some plasma-derived FVIII products downregulated CD163 surface expression and failed to upregulate the athero- and joint protective enzyme HO-1 in response to hemoglobin. CONCLUSION Plasma-derived FVIII products might promote bleeding-induced joint injury via generation of macrophages that are unable to counteract redox stress.
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Affiliation(s)
- Anne Bertling
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Münster, Germany
| | - Martin F Brodde
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Münster, Germany.,OxProtect GmbH, Münster, Germany
| | - Mayken Visser
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Münster, Germany
| | - Janina Treffon
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Münster, Germany
| | - Michelle Fennen
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Münster, Germany
| | - Anke C Fender
- Institute of Pharmacology and Clinical Pharmacology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Reinhard Kelsch
- Institute of Transfusion Medicine and Transplantation Immunology, University Hospital Münster, Münster, Germany
| | - Beate E Kehrel
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Münster, Germany
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16
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Anderson R, Feldman C. Review manuscript: Mechanisms of platelet activation by the pneumococcus and the role of platelets in community-acquired pneumonia. J Infect 2017; 75:473-485. [PMID: 28943342 DOI: 10.1016/j.jinf.2017.09.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 12/11/2022]
Abstract
There is increasing recognition of the involvement of platelets in orchestrating inflammatory responses, driving the activation of neutrophils, monocytes and vascular endothelium, which, if poorly controlled, may lead to microvascular dysfunction. Importantly, hyperreactivity of platelets has been implicated in the pathogenesis of myocardial injury and the associated particularly high prevalence of acute cardiovascular events in patients with severe community-acquired pneumonia (CAP), of which Streptococcus pneumoniae (pneumococcus) is the most commonly encountered aetiologic agent. In this context, it is noteworthy that a number of studies have documented various mechanisms by which the pneumococcus may directly promote platelet aggregation and activation. The major contributors to platelet activation include several different types of pneumococcal adhesin, the pore-forming toxin, pneumolysin, and possibly pathogen-derived hydrogen peroxide, which collectively represent a major focus of the current review. This is followed by an overview of the limited experimental studies together with a larger series of clinical studies mainly focused on all-cause CAP, which have provided evidence in support of associations between alterations in circulating platelet counts, most commonly thrombocytopenia, and a poor clinical outcome. The final section of the review covers, albeit briefly, systemic biomarkers of platelet activation which may have prognostic potential.
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Affiliation(s)
- Ronald Anderson
- Department of Immunology and Institute for Cellular and Molecular Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
| | - Charles Feldman
- Division of Pulmonology, Department of Internal Medicine, Charlotte Maxeke Johannesburg Academic Hospital and Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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17
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Wei XB, Liu YH, He PC, Yu DQ, Tan N, Zhou YL, Chen JY. The impact of admission neutrophil-to-platelet ratio on in-hospital and long-term mortality in patients with infective endocarditis. Clin Chem Lab Med 2017; 55:899-906. [PMID: 27987356 DOI: 10.1515/cclm-2016-0527] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/31/2016] [Indexed: 12/20/2022]
Abstract
BACKGROUND Infective endocarditis (IE) is associated with increased neutrophil and reduced platelet counts. We assessed the relationship between the neutrophil-to-platelet ratio (NPR) on admission and adverse outcomes in patients with IE. METHODS Patients diagnosed with IE between January 2009 and July 2015 (n=1293) were enrolled, and 1046 were finally entered into the study. Study subjects were categorized into four groups according to NPR quartiles: Q1<18.9 (n=260); Q2: 18.9-27.7 (n=258); Q3: 27.7-43.3 (n=266); and Q4>43.3 (n=262). Cox proportional hazards regression was performed to identify risk factors for long-term mortality; the optimal cut-off was evaluated by receiver operating characteristic curves. RESULTS Risk of in-hospital death increased progressively with NPR group number (1.9 vs. 5.0 vs. 9.8 vs. 14.1%, p<0.001). The follow-up period was a median of 28.8 months, during which 144 subjects (14.3%) died. Long-term mortality increased from the lowest to the highest NPR quartiles (7.6, 11.8, 17.4, and 26.2%, respectively, p<0.001). Multivariate Cox proportional hazard analysis revealed that lgNPR (HR=2.22) was an independent predictor of long-term mortality. Kaplan-Meier survival curves showed that subjects in Q4 had an increased long-term mortality compared with the other groups. CONCLUSIONS Increased NPR was associated with in-hospital and long-term mortality in patients with IE. As a simple and inexpensive index, NPR may be a useful and rapid screening tool to identify IE patients at high risk of mortality.
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Affiliation(s)
- Xue-Biao Wei
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
| | - Yuan-Hui Liu
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
| | - Peng-Cheng He
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
| | - Dan-Qing Yu
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
| | - Ning Tan
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
| | - Ying-Ling Zhou
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
| | - Ji-Yan Chen
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R
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18
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Koupenova M, Kehrel BE, Corkrey HA, Freedman JE. Thrombosis and platelets: an update. Eur Heart J 2017; 38:785-791. [PMID: 28039338 PMCID: PMC11110018 DOI: 10.1093/eurheartj/ehw550] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 10/03/2016] [Accepted: 10/25/2016] [Indexed: 12/11/2022] Open
Abstract
Haemostasis and thrombosis are complex, multifactorial processes. There is an evolving understanding of the mechanisms influencing vascular occlusion and the role of inflammation and immunity. Despite major advances in elucidating the mechanistic pathways mediating platelet function and thrombosis, challenges in the treatment of vascular occlusive diseases persist. Pharmacological advances have greatly affected thrombotic outcomes, but this has led to the unwanted side effect of bleeding. Detailed assessment of the impact of non-thrombotic diseases on haemostasis and thrombosis is necessary to better evaluate thrombotic risk and establish optimal treatment. This review will focus on recent advances in understanding the contribution of evolving risk factors to thrombosis.
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Affiliation(s)
- Milka Koupenova
- University of Massachusetts Medical School, Albert Sherman Center, 368
Plantation St, Worcester, MA 01605, USA
| | - Beate E. Kehrel
- Westfälische Wilhelms University Muenster, Münster, University Hospital,
Department of Anaesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical
Haemostasis Research, D-48149 Muenster, Germany Mendelstrasse 11, UK
| | - Heather A. Corkrey
- University of Massachusetts Medical School, Albert Sherman Center, 368
Plantation St, Worcester, MA 01605, USA
| | - Jane E. Freedman
- University of Massachusetts Medical School, Albert Sherman Center, 368
Plantation St, Worcester, MA 01605, USA
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19
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Essential roles for platelets during neutrophil-dependent or lymphocyte-mediated defense against bacterial pathogens. Blood Coagul Fibrinolysis 2017; 27:667-72. [PMID: 26588444 DOI: 10.1097/mbc.0000000000000455] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Emerging evidence from animal models suggests that platelets may participate in a wide variety of processes including the immune response against infection. More than 200 whole blood samples from patients and healthy controls were run in the System XE-5000 analyzer, and plasma fractions were separated for the following tests by ELISA, Luminex and light scattering. We describe two mechanisms by which platelets may contribute to immune function against various bacterial pathogens based on increased mean platelet volume in gram-positive bacterial infections and increased platelet counts in gram-negative bacterial infections. Gram-negative bacteria activate platelets to recruit neutrophils, which participate in the immune response against infection. During this process, fractalkine, macrophage inflammatory protein-1β, interleukin-17A, tumor necrosis factor-α and platelet-activating factor were higher in patients infected with Escherichia coli; additionally, giant platelets were observed under the microscope. Meanwhile, we found that platelets played a different role in gram-positive bacterial infections. Specifically, they could actively adhere to gram-positive bacteria in circulation and transfer them to immune sites to promote antibacterial lymphocyte expansion. During this process, complement C3 and factor XI were more highly expressed in patients infected with Staphylococcus aureus; additionally, we detected more small platelets under the microscope. Platelets participate in the immune response against both gram-negative and gram-positive bacteria, although the mechanisms differ. These results will help us understand the complex roles of platelets during infections, and direct our use of antibiotics based on clinical platelet data.
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20
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Koenen RR. The prowess of platelets in immunity and inflammation. Thromb Haemost 2016; 116:605-12. [PMID: 27384503 DOI: 10.1160/th16-04-0300] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/06/2016] [Indexed: 02/07/2023]
Abstract
Platelets not only serve as essential haemostatic cells, they also have important roles in immune defence and inflammation. Despite not having a nucleus, platelets contain physiologically relevant amounts of RNA, which can be spliced and translated into functional proteins. In addition, platelets have the ability to bind to numerous other cells, such as leukocytes and vascular cells. During those interactions, platelets can modulate cellular responses, resulting in e. g. inflammatory activation or apoptosis. Recent studies have demonstrated that platelets can influence the outcomes of bacterial and viral infection, as well as the extent of tissue injury after ischaemia. Platelets also carry considerable amounts of cytokines and growth factors in their secretory granules, preformed for rapid secretion. Those properties in combination with the sheer amount of platelets circulating in the blood stream make them an important force in the immune response during health and disease. In this overview, recent findings concerning those interesting properties of platelets beyond haemostasis are discussed.
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Affiliation(s)
- Rory R Koenen
- Rory R. Koenen, PhD, Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands, Tel.: +31 43 3881674, Fax: +31 43 3884159, E-mail:
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21
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Which are important targets in development of S. aureus mastitis vaccine? Res Vet Sci 2015; 100:88-99. [DOI: 10.1016/j.rvsc.2015.03.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/04/2015] [Accepted: 03/14/2015] [Indexed: 12/21/2022]
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22
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Ferrera C, Vilacosta I, Fernández C, López J, Sarriá C, Olmos C, Vivas D, Sáez C, Sánchez-Enrique C, Ortiz C, San Román JA. Usefulness of thrombocytopenia at admission as a prognostic marker in native valve left-sided infective endocarditis. Am J Cardiol 2015; 115:950-5. [PMID: 25708863 DOI: 10.1016/j.amjcard.2015.01.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 01/03/2015] [Accepted: 01/03/2015] [Indexed: 11/18/2022]
Abstract
In-hospital mortality of patients with infective endocarditis (IE) remains exceedingly high. Quick recognition of parameters accurately identifying high-risk patients is of paramount importance. The objective of this study was to analyze the incidence and severity of thrombocytopenia at presentation and its prognostic impact in patients with native valve left-sided IE. We studied a cohort of 533 consecutive episodes of native valve left-sided IE prospectively recruited. We distinguished 2 groups: group I (n = 175), episodes who had thrombocytopenia at admission, and group II (n = 358) gathered all the episodes who did not. Thrombocytopenia at admission was defined as a platelet count of <150,000/μl. No differences were found in the need for surgery, but in-hospital mortality was significantly higher in patients with thrombocytopenia (p <0.001). Mortality rate was associated with the degree of thrombocytopenia (p <0.001). In the multivariable analysis, thrombocytopenia at admission was an independent predictor of higher mortality (p = 0.002). A synergistic interaction between thrombocytopenia and Staphylococcus aureus on mortality risk was also observed (p = 0.04). In conclusion, thrombocytopenia at admission is an early risk marker of increased mortality in patients with native valve left-sided IE. Mortality rates increased with increasing severity of thrombocytopenia. Thrombocytopenia at admission should be used as an early marker for risk stratification in patients with native valve IE to identify those at risk of complicated in-hospital evolution and increased mortality.
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Affiliation(s)
- Carlos Ferrera
- Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid, Spain.
| | - Isidre Vilacosta
- Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid, Spain
| | | | - Javier López
- Instituto de Ciencias del Corazón (ICICOR), Hospital Universitario de Valladolid, Valladolid, Spain
| | - Cristina Sarriá
- Servicio de Medicina Interna, Hospital Universitario de la Princesa, Madrid, Spain
| | - Carmen Olmos
- Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid, Spain
| | - David Vivas
- Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid, Spain
| | - Carmen Sáez
- Servicio de Medicina Interna, Hospital Universitario de la Princesa, Madrid, Spain
| | | | - Carlos Ortiz
- Instituto de Ciencias del Corazón (ICICOR), Hospital Universitario de Valladolid, Valladolid, Spain
| | - José Alberto San Román
- Instituto de Ciencias del Corazón (ICICOR), Hospital Universitario de Valladolid, Valladolid, Spain
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Hsu RB, Lin FY. Methicillin Resistance and Risk Factors for Embolism inStaphylococcus aureusInfective Endocarditis. Infect Control Hosp Epidemiol 2015; 28:860-6. [PMID: 17564990 DOI: 10.1086/518727] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Accepted: 12/07/2006] [Indexed: 11/03/2022]
Abstract
Objective.Infective endocarditis caused byStaphylococcus aureusis an ominous prognosis associated with a high prevalence of embolic episodes and neurological involvement. Whether methicillin resistance decreases the risk of embolism in infective endocarditis is unclear. We sought to assess the association between methicillin resistance and risk factors for embolism in S.aureusinfective endocarditis.Design.Retrospective chart review. Data from patients with infective endocarditis due to methicillin-resistantS. aureus werecompared with data from patients with endocarditis due to methicillin-susceptibleS. aureus.Logistic regression was used to identify independent risk factors for embolism.Setting.A 2,000-bed, university-affiliated tertiary care hospital.Patients.Between 1995 and 2005, 123 patients withS. aureusinfective endocarditis were included in the study. There were 74 male patients and 49 female patients, with a median age of 54 years (range, 0-89 years).Results.Of 123 infections, 30 (24%) were nosocomial infections, and 14 (11%) were prosthetic valve infections. Of 123S. aureusisolates, 48 (39%) were methicillin resistant. In total, embolism occurred in 45 (37%) of these patients: pulmonary embolism in 22 (18%), cerebral embolism in 21 (17%), and peripheral embolism in 6 (5%). The independent risk factors for an embolism were injection drug use, presence of a cardiac vegetation with a size of 10 mm or greater, and absence of nosocomial infection. For 83 patients with aortic or mitral infective endocarditis, independent risk factors for an embolism were the presence of a cardiac vegetation with a size of 10 mm or greater and endocarditis due to methicillin-susceptibleS. aureus.Overall, in-hospital death occurred for 32 (26%) of 123 Patients. Methicillin-resistant infection was not an independent risk factor for death.Conclusions.Methicillin-resistant S.aureusinfection was associated with decreased risk of embolism in left-side endocarditis, but was not associated with in-hospital death.
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Affiliation(s)
- Ron-Bin Hsu
- Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan, Republic of China
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24
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Jaglic Z, Desvaux M, Weiss A, Nesse LL, Meyer RL, Demnerova K, Schmidt H, Giaouris E, Sipailiene A, Teixeira P, Kačániová M, Riedel CU, Knøchel S. Surface adhesins and exopolymers of selected foodborne pathogens. MICROBIOLOGY-SGM 2014; 160:2561-2582. [PMID: 25217529 DOI: 10.1099/mic.0.075887-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The ability of bacteria to bind different compounds and to adhere to biotic and abiotic surfaces provides them with a range of advantages, such as colonization of various tissues, internalization, avoidance of an immune response, and survival and persistence in the environment. A variety of bacterial surface structures are involved in this process and these promote bacterial adhesion in a more or less specific manner. In this review, we will focus on those surface adhesins and exopolymers in selected foodborne pathogens that are involved mainly in primary adhesion. Their role in biofilm development will also be considered when appropriate. Both the clinical impact and the implications for food safety of such adhesion will be discussed.
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Affiliation(s)
- Zoran Jaglic
- Veterinary Research Institute, Brno, Czech Republic
| | - Mickaël Desvaux
- INRA, UR454 Microbiologie, F-63122 Saint-Genès Champanelle, France
| | - Agnes Weiss
- Department of Food Microbiology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany
| | | | - Rikke L Meyer
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Katerina Demnerova
- Institute of Chemical Technology, Faculty of Food and Biochemical Technology, Department of Biochemistry and Microbiology, Technicka 5, Prague, 166 28, Czech Republic
| | - Herbert Schmidt
- Department of Food Microbiology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany
| | - Efstathios Giaouris
- Department of Food Science and Nutrition, Faculty of the Environment, University of the Aegean, 81400 Myrina, Lemnos Island, Greece
| | | | - Pilar Teixeira
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal
| | | | - Christian U Riedel
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Susanne Knøchel
- Department of Food Science, University of Copenhagen, Rolighedsvej 30, Frederiksberg C 1958, Denmark
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25
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Kohler TP, Gisch N, Binsker U, Schlag M, Darm K, Völker U, Zähringer U, Hammerschmidt S. Repeating structures of the major staphylococcal autolysin are essential for the interaction with human thrombospondin 1 and vitronectin. J Biol Chem 2013; 289:4070-82. [PMID: 24371140 DOI: 10.1074/jbc.m113.521229] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Human thrombospondin 1 (hTSP-1) is a matricellular glycoprotein facilitating bacterial adherence to and invasion into eukaryotic cells. However, the bacterial adhesin(s) remain elusive. In this study, we show a dose-dependent binding of soluble hTSP-1 to Gram-positive but not Gram-negative bacteria. Diminished binding of soluble hTSP-1 to proteolytically pretreated staphylococci suggested a proteinaceous nature of potential bacterial adhesin(s) for hTSP-1. A combination of separation of staphylococcal surface proteins by two-dimensional gel electrophoresis with a ligand overlay assay with hTSP-1 and identification of the target protein by mass spectrometry revealed the major staphylococcal autolysin Atl as a bacterial binding protein for hTSP-1. Binding experiments with heterologously expressed repeats of the AtlE amidase from Staphylococcus epidermidis suggest that the repeating sequences (R1ab-R2ab) of the N-acetyl-muramoyl-L-alanine amidase of Atl are essential for binding of hTSP-1. Atl has also been identified previously as a staphylococcal vitronectin (Vn)-binding protein. Similar to the interaction with hTSP-1, the R1ab-R2ab repeats of Atl are shown here to be crucial for the interaction of Atl with the complement inhibition and matrix protein Vn. Competition assays with hTSP-1 and Vn revealed the R1ab-R2ab repeats of AtlE as the common binding domain for both host proteins. Furthermore, Vn competes with hTSP-1 for binding to Atl repeats and vice versa. In conclusion, this study identifies the Atl repeats as bacterial adhesive structures interacting with the human glycoproteins hTSP-1 and Vn. Finally, this study provides insight into the molecular interplay between hTSP-1 and Vn, respectively, and a bacterial autolysin.
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Werdan K, Dietz S, Löffler B, Niemann S, Bushnaq H, Silber RE, Peters G, Müller-Werdan U. Mechanisms of infective endocarditis: pathogen–host interaction and risk states. Nat Rev Cardiol 2013; 11:35-50. [DOI: 10.1038/nrcardio.2013.174] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Pappelbaum KI, Gorzelanny C, Grässle S, Suckau J, Laschke MW, Bischoff M, Bauer C, Schorpp-Kistner M, Weidenmaier C, Schneppenheim R, Obser T, Sinha B, Schneider SW. Ultralarge von Willebrand factor fibers mediate luminal Staphylococcus aureus adhesion to an intact endothelial cell layer under shear stress. Circulation 2013; 128:50-9. [PMID: 23720451 DOI: 10.1161/circulationaha.113.002008] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND During pathogenesis of infective endocarditis, Staphylococcus aureus adherence often occurs without identifiable preexisting heart disease. However, molecular mechanisms mediating initial bacterial adhesion to morphologically intact endocardium are largely unknown. METHODS AND RESULTS Perfusion of activated human endothelial cells with fluorescent bacteria under high-shear-rate conditions revealed 95% attachment of the S aureus by ultralarge von Willebrand factor (ULVWF). Flow experiments with VWF deletion mutants and heparin indicate a contribution of the A-type domains of VWF to bacterial binding. In this context, analyses of different bacterial deletion mutants suggest the involvement of wall teichoic acid but not of staphylococcal protein A. The presence of inactivated platelets and serum increased significantly ULVWF-mediated bacterial adherence. ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin motifs 13) caused a dose-dependent reduction of bacterial binding and a reduced length of ULVWF, but single cocci were still tethered by ULVWF at physiological levels of ADAMTS13. To further prove the role of VWF in vivo, we compared wild-type mice with VWF knockout mice. Binding of fluorescent bacteria was followed in tumor necrosis factor-α-stimulated tissue by intravital microscopy applying the dorsal skinfold chamber model. Compared with wild-type mice (n=6), we found less bacteria in postcapillary (60±6 versus 32±5 bacteria) and collecting venules (48±5 versus 18±4 bacteria; P<0.05) of VWF knockout mice (n=5). CONCLUSIONS Our data provide the first evidence that ULVWF contributes to the initial pathogenic step of S aureus-induced endocarditis in patients with an apparently intact endothelium. An intervention reducing the ULVWF formation with heparin or ADAMTS13 suggests novel therapeutic options to prevent infective endocarditis.
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Affiliation(s)
- Karin I Pappelbaum
- Experimental Dermatology, Department of Dermatology, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
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E. Kehrel B, F. Brodde M. State of the art in platelet function testing. Transfus Med Hemother 2013; 40:73-86. [PMID: 23653569 PMCID: PMC3638976 DOI: 10.1159/000350469] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 12/20/2022] Open
Abstract
Platelets perform many functions in hemostasis but also in other areas of physiology and pathology. Therefore, it is obvious that many different function tests have been developed, each one conceived and standardized for a special purpose. This review will summarize the different fields in which platelet function testing is currently in use; diagnostics of patients with bleeding disorders, monitoring patients' response to anti-platelet therapy, monitoring in transfusion medicine (blood donors, platelet concentrates, and after transfusion), and monitoring in perioperative medicine to predict bleeding tendency. The second part of the review outlines different methods for platelet function testing, spanning bleeding time, and platelet counting as well as determining platelet adhesion, platelet secretion, platelet aggregation, platelet morphology, platelet signal transduction, platelet procoagulant activity, platelet apoptosis, platelet proteomics, and molecular biology.
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Affiliation(s)
- Beate E. Kehrel
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Germany
| | - Martin F. Brodde
- Department of Anesthesiology, Intensive Care and Pain Medicine, Experimental and Clinical Hemostasis, University of Münster, Germany
- OxProtect GmbH, Münster, Germany
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Zecconi A, Scali F. Staphylococcus aureus virulence factors in evasion from innate immune defenses in human and animal diseases. Immunol Lett 2013; 150:12-22. [PMID: 23376548 DOI: 10.1016/j.imlet.2013.01.004] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/09/2012] [Accepted: 01/08/2013] [Indexed: 01/04/2023]
Abstract
In the last decades, Staphylococcus aureus acquired a dramatic relevance in human and veterinary medicine for different reasons, one of them represented by the increasing prevalence of antibiotic resistant strains. However, antibiotic resistance is not the only weapon in the arsenal of S. aureus. Indeed, these bacteria have plenty of virulence factors, including a vast ability to evade host immune defenses. The innate immune system represents the first line of defense against invading pathogens. This system consists of three major effector mechanisms: antimicrobial peptides and enzymes, the complement system and phagocytes. In this review, we focused on S. aureus virulence factors involved in the immune evasion in the first phases of infection: TLR recognition avoidance, adhesins affecting immune response and resistance to host defenses peptides and polypeptides. Studies of innate immune defenses and their role against S. aureus are important in human and veterinary medicine given the problems related to S. aureus antimicrobial resistance. Moreover, due to the pathogen ability to manipulate the immune response, these data are needed to develop efficacious vaccines or molecules against S. aureus.
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Affiliation(s)
- Alfonso Zecconi
- Università degli Studi di Milano, Dip. Scienze Veterinarie e Sanità Pubblica, Via Celoria 10, 20133 Milano, Italy.
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Furuya H, Ikeda R. Interaction of triosephosphate isomerase from Staphylococcus aureus with plasminogen. Microbiol Immunol 2012; 55:855-62. [PMID: 22003920 DOI: 10.1111/j.1348-0421.2011.00392.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Triosephosphate isomerase (TPI; EC 5. 3. 1. 1) displayed on the cell surface of Staphylococcus aureus acts as an adhesion molecule that binds to the capsule of Cryptococcus neoformans, a fungal pathogen. This study investigated the function of TPI on the cell surface of S. aureus and its interactions with biological substances such as fibronectin, fibrinogen, plasminogen, and thrombin were investigated. Binding of TPI to plasminogen was demonstrated by both surface plasmon resonance analysis and Far-Western blotting. It is suggested that lysine residues contribute to this binding because the interaction was inhibited by ɛ-aminocaproic acid. Activation of plasminogen to plasmin by staphylokinase or tissue plasminogen activator decreased in the presence of TPI, whereas TPI was degraded by plasmin. In other experiments, intact S. aureus cells had the ability to both increase and decrease plasminogen activation depending on the number of cells. Several molecules expressed on the surface of S. aureus were predicted to interact with plasminogen, resulting in its increased or decreased activation. These findings indicate that S. aureus sometimes localizes and sometimes disseminates in the host, depending on the molecules expressed under various conditions.
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Affiliation(s)
- Hiromi Furuya
- Department of Microbiology, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
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31
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Horn M, Bertling A, Brodde MF, Müller A, Roth J, Van Aken H, Jurk K, Heilmann C, Peters G, Kehrel BE. Human neutrophil alpha-defensins induce formation of fibrinogen and thrombospondin-1 amyloid-like structures and activate platelets via glycoprotein IIb/IIIa. J Thromb Haemost 2012; 10:647-61. [PMID: 22268819 DOI: 10.1111/j.1538-7836.2012.04640.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Human neutrophil α-defensins (HNPs) are important constituents of the innate immune system. Beyond their antimicrobial properties, HNPs also have pro-inflammatory features. While HNPs in plasma from healthy individuals are barely detectable, their level is strongly elevated in septic plasma and plasma from patients with acute coronary syndromes. OBJECTIVES As thrombosis and inflammation are intertwined processes and activation of human polymorphonuclear leukocytes (PMNL) and subsequent degranulation is associated with full activation of surrounding platelets, we studied the effect of HNPs on platelet function. METHODS The effect of HNPs on platelet activation parameters and apoptosis was investigated via aggregometry, flow cytometry, confocal microscopy and the ELISA technique. RESULTS It was found that HNPs activate platelets in pathophysiologically relevant doses, inducing fibrinogen and thrombospondin-1 binding, aggregation, granule secretion, sCD40L shedding, and procoagulant activity. HNPs bound directly to the platelet membrane, induced membrane pore formation, microparticle formation, mitochondrial membrane depolarization and caspase-3-activity. Confocal microscopy revealed the HNP-induced formation of polymeric fibrinogen and thrombospondin-1 amyloid-like structures, which bound microorganisms. Platelets adhered to these structures and formed aggregates. Blocking of glycoprotein IIb/IIIa (GPIIb/IIIa) markedly inhibited HNP-induced platelet activation. In addition, heparin, heparinoid, serpins and α(2)-macroglobulin, which all bind to HNPs, blocked HNP-1-induced platelet activation in contrast to direct thrombin inhibitors such as hirudin. CONCLUSIONS HNPs activate platelets and induce platelet apoptosis by formation of amyloid-like proteins. As these structures entrapped bacteria and fungi, they might reflect an additional function of HNPs in host defense. The described mechanism links again thrombosis and infection.
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Affiliation(s)
- M Horn
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University of Muenster, Muenster, Germany
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Vanassche T, Kauskot A, Verhaegen J, Peetermans WE, van Ryn J, Schneewind O, Hoylaerts MF, Verhamme P. Fibrin formation by staphylothrombin facilitates Staphylococcus aureus-induced platelet aggregation. Thromb Haemost 2012; 107:1107-21. [PMID: 22437005 DOI: 10.1160/th11-12-0891] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/01/2012] [Indexed: 11/05/2022]
Abstract
Interactions of Staphylococcus aureus (S. aureus) and platelets play an important role in the pathogenesis of intravascular infections such as infective endocarditis (IE). A typical feature of S. aureus is the ability to generate thrombin activity through the secretion of two prothrombin activating molecules, staphylocoagulase and von Willebrand factor-binding protein (vWbp), which bind to human prothrombin to form the enzymatically active staphylothrombin complex. The role of staphylothrombin in the interaction between S. aureus and platelets has not yet been studied. We found that in contrast with thrombin, staphylothrombin did not directly activate human platelets. However, the staphylothrombin-mediated conversion of fibrinogen to fibrin initiated platelet aggregation and secondary activation and facilitated S. aureus-platelet interactions. Both the genetic absence of staphylocoagulase and vWbp and pharmacological inhibition of staphylothrombin increased the lag time to aggregation, and reduced platelet trapping by S. aureus in high shear stress conditions. The combined inhibition of staphylothrombin and immunoglobulin binding to platelets completely abolished the ability of S. aureus to aggregate platelets in vitro. In conclusion, although staphylothrombin did not directly activate platelets, the formation of a fibrin scaffold facilitated bacteria-platelet interaction, and the inhibition of staphylothrombin resulted in a reduced activation of platelets by S. aureus.
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Affiliation(s)
- Thomas Vanassche
- Center for Molecular and Vascular Biology, University of Leuven, University Hospitals Leuven, B-3000 Leuven, Belgium.
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McAdow M, Missiakas DM, Schneewind O. Staphylococcus aureus secretes coagulase and von Willebrand factor binding protein to modify the coagulation cascade and establish host infections. J Innate Immun 2012; 4:141-8. [PMID: 22222316 PMCID: PMC3388267 DOI: 10.1159/000333447] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/21/2011] [Indexed: 12/14/2022] Open
Abstract
Clinical isolates of Staphylococcus aureus secrete coagulases, polypeptides that bind to and activate prothrombin, thereby converting fibrinogen to fibrin and promoting the clotting of plasma or blood. Two staphylococcal products, the canonical coagulase (Coa) as well as the recently identified von Willebrand factor binding protein (vWbp), promote similar modifications of the coagulation cascade during host infection. Staphylococcal binding to fibrinogen or fibrin is an important attribute of disease pathogenesis, which leads to the formation of abscesses and bacterial persistence in host tissues and also enables the pathogen to cause lethal sepsis. Circumstantial evidence suggests that the product of coagulase activity, staphylococci captured within a fibrin meshwork, enable this pathogen to disseminate as thromboembolic lesions and to resist opsonophagocytic clearance by host immune cells. In addition, the coagulation products of staphylococci appear to display discrete differences when compared to those of thrombin-mediated coagulation, the latter representing a key innate defense mechanism against many invading pathogens. Preclinical evidence suggests that inactivation or neutralization of coagulases may prevent the pathogenesis of staphylococcal infections, a strategy that could be used to combat the current epidemic of hospital-acquired infections with drug-resistant S. aureus isolates.
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Affiliation(s)
| | | | - Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, Ill., USA
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Gafter-Gvili A, Mansur N, Bivas A, Zemer-Wassercug N, Bishara J, Leibovici L, Paul M. Thrombocytopenia in Staphylococcus aureus bacteremia: risk factors and prognostic importance. Mayo Clin Proc 2011; 86:389-96. [PMID: 21531882 PMCID: PMC3084641 DOI: 10.4065/mcp.2010.0705] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
OBJECTIVE To identify risk factors and outcomes associated with thrombocytopenia at sepsis onset in Staphylococcus aureus bacteremia. PATIENTS AND METHODS This single-center, retrospective, cohort study consists of all adult patients with a first episode of clinical S aureus bacteremia between April 1, 1988, and September 30, 1994, and between January 1, 1999, and December 31, 2007. Thrombocytopenia was defined as a platelet count less than 150 × 10(9)/L. The primary outcome was 30-day all-cause mortality. Risk factors for 30-day all-cause mortality were identified using univariate and multivariable analyses. Multivariable analysis was conducted using forward step logistic regression analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for risk of death. RESULTS A total of 1052 patients had clinical S aureus bacteremia. Thrombocytopenia at sepsis onset was present in 235 patients (22.3%). Thrombocytopenia was associated with community-acquired bacteremia, infections caused by methicillin-sensitive S aureus, high-magnitude bacteremia (defined as >4 positive blood cultures [≥ 3 separate positive blood culture sets]), and endocarditis. Patients with thrombocytopenia presented more commonly with severe sepsis reflected by septic shock and acute renal failure. Thirty-day mortality was significantly higher among patients with thrombocytopenia (132/235 [56.2%]) vs those without thrombocytopenia (281/817 [34.4%]; P<.001). Higher mortality was associated with the degree of thrombocytopenia. In multivariable analysis, thrombocytopenia at baseline remained an independent risk factor for 30-day mortality (OR, 2.82; 95% CI, 1.87-4.24). The adjusted association between thrombocytopenia and death remained similar among the 917 patients with monomicrobial bacteremia (OR, 2.88; 95% CI, 1.83-4.53) and the 945 patients who did not die within the first 48 hours (OR, 2.88; 95% CI, 1.87-4.45.). CONCLUSION We observed a strong association between thrombocytopenia at sepsis onset and all-cause mortality in S aureus bacteremia, possibly related to mechanisms other than sepsis alone.
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Affiliation(s)
- Anat Gafter-Gvili
- Department of Medicine E, Rabin Medical Center, Beilinson Hospital, Petah-Tikva 49100, Israel.
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Abstract
Although their central role is to control bleeding and to induce thrombosis, platelets are important inflammatory and immune cells as well as modulators of angiogenesis. This review focuses on the different roles of platelets in hemostasis, thrombosis, inflammation, arteriosclerosis, angiogenesis, antimicrobial host defense and hematogenous tumor metastasis. Platelets are the central regulators of hemostasis. On their surface the important thrombin burst takes place. Platelets cause atherothrombotic vascular occlusions. However, they are probably involved in early stages of arteriosclerosis, e.g. extravasation of leukocytes at sites of vascular injury, formation of foam cells and proliferation of smooth muscle cells. These processes are triggered by secretion of proinflammatory substances and growth factors as well as by platelet-cell interactions via specific adhesive axes. During infections platelets kill pathogens through secretion of antimicrobial substances and extracellular traps or nets. Platelets facilitate the revascularisation of ischemic tissue and therefore even promote tumor growth.
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Affiliation(s)
- K Jurk
- Experimentelle und Klinische Hämostaseologie, Klinik und Poliklinik für Anästhesiologie und operative Intensivmedizin, Universitätsklinikum Münster, Mendelstraße 11, 48149, Münster, Deutschland
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Gray platelet syndrome: natural history of a large patient cohort and locus assignment to chromosome 3p. Blood 2010; 116:4990-5001. [PMID: 20709904 DOI: 10.1182/blood-2010-05-286534] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Gray platelet syndrome (GPS) is an inherited bleeding disorder characterized by macrothrombocytopenia and absence of platelet α-granules resulting in typical gray platelets on peripheral smears. GPS is associated with a bleeding tendency, myelofibrosis, and splenomegaly. Reports on GPS are limited to case presentations. The causative gene and underlying pathophysiology are largely unknown. We present the results of molecular genetic analysis of 116 individuals including 25 GPS patients from 14 independent families as well as novel clinical data on the natural history of the disease. The mode of inheritance was autosomal recessive (AR) in 11 and indeterminate in 3 families. Using genome-wide linkage analysis, we mapped the AR-GPS gene to a 9.4-Mb interval on 3p21.1-3p22.1, containing 197 protein-coding genes. Sequencing of 1423 (69%) of the 2075 exons in the interval did not identify the GPS gene. Long-term follow-up data demonstrated the progressive nature of the thrombocytopenia and myelofibrosis of GPS resulting in fatal hemorrhages in some patients. We identified high serum vitamin B(12) as a consistent, novel finding in GPS. Chromosome 3p21.1-3p22.1 has not been previously linked to a platelet disorder; identification of the GPS gene will likely lead to the discovery of novel components of platelet organelle biogenesis. This study is registered at www.clinicaltrials.gov as NCT00069680 and NCT00369421.
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Yeaman MR. Bacterial-platelet interactions: virulence meets host defense. Future Microbiol 2010; 5:471-506. [PMID: 20210555 DOI: 10.2217/fmb.09.112] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Platelets have historically been viewed as cell fragments that only mediate blood coagulation. Yet, platelets have as - or perhaps even more - important roles in tissue remodeling, modulation of inflammation and antimicrobial host defense. It is evident that platelets interact with prokaryotes directly and indirectly through multiple molecular and cellular mechanisms. The important roles of platelets in antibacterial host defense can be exemplified through contemporary themes in platelet immunobiology. Platelets have unambiguous structures and functions of host defense effector cells. Recent discoveries reveal platelet expression of toll-like and purinonergic receptors, which enable detection and response to bacterial infection, degranulation of an array of microbicidal peptides and coordination of other molecular and cellular host defenses. From multiple perspectives, platelets are now increasingly recognized as critical innate immune effector cells that also bridge and facilitate optimization of adaptive immunity. It follows that clinical deficiencies in platelet quantity or quality are now recognized correlates of increased risk and severity of bacterial and other infections. Along these lines, new evidence suggests that certain prokaryotic organisms may be capable of exploiting platelet interactions to gain a virulence advantage. Indeed, certain bacterial pathogens appear to have evolved highly coordinated means by which to seize opportunities to bind to surfaces of activated platelets, and exploit them to establish or propagate infection. Hence, it is conceivable that certain bacterial pathogens subvert platelet functions. From these perspectives, the net consequences of bacterial virulence versus platelet host defenses likely decide initial steps towards the ultimate result of infection versus immunity.
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Affiliation(s)
- Michael R Yeaman
- Department of Medicine, David Geffen School of Medicine at UCLA, Harbor-UCLA Medical Center, 1124 West Carson Street, RB-2, Torrance, CA 90502, USA.
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38
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Abstract
Platelets interact with bacterial pathogens through a wide array of cellular and molecular mechanisms. The consequences of this interaction may significantly influence the balance between infection and immunity. On the one hand, recent data indicate that certain bacteria may be capable of exploiting these interactions to gain a virulence advantage. Indeed, certain bacterial pathogens appear to have evolved specific ways in which to subvert activated platelets. Hence, it is conceivable that some bacterial pathogens exploit platelet responses. On the other hand, platelets are now known to possess unambiguous structures and functions of host defense effector cells. Recent discoveries emphasize critical features enabling such functions, including expression of toll-like receptors that detect hallmark signals of bacterial infection, an array of microbicidal peptides, as well as other host defense molecules and functions. These concepts are consistent with increased risk and severity of bacterial infection as correlates of clinical abnormalities in platelet quantity and quality. In these respects, the molecular and cellular roles of platelets in host defense against bacterial pathogens are explored with attention on advances in platelet immunobiology.
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Affiliation(s)
- Michael R Yeaman
- Division of Infectious Diseases, St. John's Cardiovascular Research Center, Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, Torrance, CA 90502, USA.
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Schroeder K, Jularic M, Horsburgh SM, Hirschhausen N, Neumann C, Bertling A, Schulte A, Foster S, Kehrel BE, Peters G, Heilmann C. Molecular characterization of a novel Staphylococcus aureus surface protein (SasC) involved in cell aggregation and biofilm accumulation. PLoS One 2009; 4:e7567. [PMID: 19851500 PMCID: PMC2761602 DOI: 10.1371/journal.pone.0007567] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 09/01/2009] [Indexed: 01/30/2023] Open
Abstract
Background Staphylococci belong to the most important pathogens causing implant-associated infections. Colonization of the implanted medical devices by the formation of a three-dimensional structure made of bacteria and host material called biofilm is considered the most critical factor in these infections. To form a biofilm, bacteria first attach to the surface of the medical device, and then proliferate and accumulate into multilayered cell clusters. Biofilm accumulation may be mediated by polysaccharide and protein factors. Methology/Principal Findings The information on Staphylococcus aureus protein factors involved in biofilm accumulation is limited, therefore, we searched the S. aureus Col genome for LPXTG-motif containing potential surface proteins and chose the so far uncharacterized S. aureus surface protein C (SasC) for further investigation. The deduced SasC sequence consists of 2186 amino acids with a molecular mass of 238 kDa and has features typical of Gram-positive surface proteins, such as an N-terminal signal peptide, a C-terminal LPXTG cell wall anchorage motif, and a repeat region consisting of 17 repeats similar to the domain of unknown function 1542 (DUF1542). We heterologously expressed sasC in Staphylococcus carnosus, which led to the formation of huge cell aggregates indicative of intercellular adhesion and biofilm accumulation. To localize the domain conferring cell aggregation, we expressed two subclones of sasC encoding either the N-terminal domain including a motif that is found in various architectures (FIVAR) or 8 of the DUF1542 repeats. SasC or its N-terminal domain, but not the DUF1542 repeat region conferred production of huge cell aggregates, higher attachment to polystyrene, and enhanced biofilm formation to S. carnosus and S. aureus. SasC does not mediate binding to fibrinogen, thrombospondin-1, von Willebrand factor, or platelets as determined by flow cytometry. Conclusions/Significance Thus, SasC represents a novel S. aureus protein factor involved in cell aggregation and biofilm formation, which may play an important role in colonization during infection with this important pathogen.
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Affiliation(s)
- Katrin Schroeder
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Mario Jularic
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Samantha M. Horsburgh
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Nina Hirschhausen
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Claudia Neumann
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Anne Bertling
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University Hospital of Münster, Münster, Germany
| | - Anja Schulte
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University Hospital of Münster, Münster, Germany
| | - Simon Foster
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Beate E. Kehrel
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University Hospital of Münster, Münster, Germany
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Christine Heilmann
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
- * E-mail:
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Broekhuizen CAN, de Boer L, Schipper K, Jones CD, Quadir S, Feldman RG, Vandenbroucke-Grauls CMJE, Zaat SAJ. The influence of antibodies on Staphylococcus epidermidis adherence to polyvinylpyrrolidone-coated silicone elastomer in experimental biomaterial-associated infection in mice. Biomaterials 2009; 30:6444-50. [PMID: 19716173 DOI: 10.1016/j.biomaterials.2009.08.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2009] [Accepted: 08/09/2009] [Indexed: 11/30/2022]
Abstract
Biomaterial-associated infection (BAI) is a major problem in modern medicine, and is often caused by Staphylococcus epidermidis. We aimed to raise monoclonal antibodies (mAbs) against major surface protein antigens of S. epidermidis, and to assess their possible protective activity in experimental BAI. Mice were vaccinated with a cell wall protein preparation of S. epidermidis. A highly immunodominant antigen was identified as Accumulation-associated protein (Aap). mAbs against Aap and against surface-exposed lipoteichoic acid (LTA) were used for passive immunization of mice in experimental biomaterial-associated infection. Neither anti-Aap nor anti-LTA mAbs showed protection. Either with or without antibodies, tissue surrounding the implants was more often culture positive than the implants themselves, but bacterial adherence to the implants was significantly increased in mice injected with anti-LTA. In vitro, anti-Aap and anti-LTA did show binding to S. epidermidis, but no opsonic activity was observed. We conclude that antibodies against S. epidermidis LTA or Aap showed no opsonic activity and did not protect mice against BAI. Moreover, the increase in binding to implanted biomaterial suggests that passive immunization may increase the risk for BAI.
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Affiliation(s)
- Corine A N Broekhuizen
- Department of Medical Microbiology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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Platelet antistaphylococcal responses occur through P2X1 and P2Y12 receptor-induced activation and kinocidin release. Infect Immun 2008; 76:5706-13. [PMID: 18824536 DOI: 10.1128/iai.00935-08] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelets (PLTs) act in antimicrobial host defense by releasing PLT microbicidal proteins (PMPs) or PLT kinocidins (PKs). Receptors mediating staphylocidal efficacy and PMP or PK release versus isogenic PMP-susceptible (ISP479C) and -resistant (ISP479R) Staphylococcus aureus strains were examined in vitro. Isolated PLTs were incubated with ISP479C or ISP479R (PLT/S. aureus ratio range, 1:1 to 10,000:1) in the presence or absence of a panel of PLT inhibitors, including P2X and P2Y receptor antagonists of increasingly narrow specificity, and PLT adhesion receptors (CD41, CD42b, and CD62P). PLT-to-S. aureus exposure ratios of > or = 10:1 yielded significant reductions in the viability of both strains. Results from reversed-phase high-performance liquid chromatography indicated that staphylocidal PLT releasates contained PMPs and PKs. At ratios below 10:1, the PLT antistaphylococcal efficacy relative to the intrinsic S. aureus PMP-susceptible or -resistant phenotype diminished. Apyrase (an agent of ADP degradation), suramin (a general P2 receptor antagonist), pyridoxal 5'-phosphonucleotide derivative (a specific P2X(1) antagonist), and cangrelor (a specific P2Y(12) antagonist) mitigated the PLT staphylocidal response against both strains, correlating with reduced levels of PMP and PK release. Specific inhibition occurred in the presence and absence of homologous plasma. The antagonism of the thromboxane A(2), cyclooxygenase-1/cyclooxygenase-2, or phospholipase C pathway or the hindrance of surface adhesion receptors failed to impede PLT anti-S. aureus responses. These results suggest a multifactorial PLT anti-S. aureus response mechanism involving (i) a PLT-to-S. aureus ratio sufficient for activation; (ii) the ensuing degranulation of PMPs, PKs, ADP, and/or ATP; (iii) the activation of P2X(1)/P2Y(12) receptors on adjacent PLTs; and (iv) the recursive amplification of PMP and PK release from these PLTs.
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Staphylococcal Presence Alters Thrombus Formation Under Physiological Shear Conditions in Whole Blood Studies. Ann Biomed Eng 2008; 36:349-55. [DOI: 10.1007/s10439-007-9434-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Accepted: 12/26/2007] [Indexed: 10/22/2022]
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Rennemeier C, Hammerschmidt S, Niemann S, Inamura S, Zähringer U, Kehrel BE. Thrombospondin-1 promotes cellular adherence of gram-positive pathogens via recognition of peptidoglycan. FASEB J 2007; 21:3118-32. [PMID: 17507668 DOI: 10.1096/fj.06-7992com] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Thrombospondin-1 (TSP1) is a matricellular glycoprotein that has key roles in interactions between human cells and components of the extracellular matrix. Here we report a novel role for the lectin TSP1 in pathogen-host interactions. Binding assays and flow cytometric analysis demonstrate that Streptococcus pneumoniae and other gram-positive pathogens including S. pyogenes, Staphylococcus aureus, and Listeria monocytogenes interact specifically with human TSP1. We also show for the first time that host cell-bound TSP1 promotes adherence of gram-positive pathogens to human epithelial and endothelial cell lines. Pretreatment of bacteria with sodium periodate but not Pronase E substantially reduced TSP1-mediated bacterial adherence to host cells, suggesting that a glycoconjugate on the bacterial cell surface functions as the receptor for TSP1. Lipoteichoic acids did not affect TSP1-mediated adherence of S. pneumoniae to host cells. In contrast, attachment of S. pneumoniae and other gram-positive pathogens to host cells via TSP1 was blocked by soluble peptidoglycan, indicating recognition of bacterial peptidoglycan by TSP1. In conclusion, our results demonstrate that recognition of gram-positive pathogens by TSP1 promotes bacterial colonization of host tissue cells. In this scenario, peptidoglycan functions as adhesin and TSP1 acts as a molecular bridge linking gram-positive bacteria with receptors on the host cell.
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Affiliation(s)
- Claudia Rennemeier
- University of Wuerzburg, Research Center for Infectious Diseases, Wuerzburg, Germany
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44
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Antimicrobial Host Defense. Platelets 2007. [DOI: 10.1016/b978-012369367-9/50802-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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45
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Abstract
In recent years, the frequency of serious cardiovascular infections such as endocarditis has increased, particularly in association with nosocomially acquired antibiotic-resistant pathogens. Growing evidence suggests a crucial role for the interaction of bacteria with human platelets in the pathogenesis of cardiovascular infections. Here, we review the nature of the interactions between platelets and bacteria, and the role of these interactions in the pathogenesis of endocarditis and other cardiovascular diseases.
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Affiliation(s)
- J Ross Fitzgerald
- Centre for Infectious Diseases, The Chancellor's Building, New Royal Infirmary, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
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46
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Fitzgerald JR, Loughman A, Keane F, Brennan M, Knobel M, Higgins J, Visai L, Speziale P, Cox D, Foster TJ. Fibronectin-binding proteins of Staphylococcus aureus mediate activation of human platelets via fibrinogen and fibronectin bridges to integrin GPIIb/IIIa and IgG binding to the FcgammaRIIa receptor. Mol Microbiol 2006; 59:212-30. [PMID: 16359330 DOI: 10.1111/j.1365-2958.2005.04922.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Staphylococcus aureus is a leading cause of infective endocarditis (IE). Platelet activation promoted by S. aureus resulting in aggregation and thrombus formation is an important step in the pathogenesis of IE. Here, we report that the fibrinogen/fibronectin-binding proteins FnBPA and FnBPB are major platelet-activating factors on the surface of S. aureus from the exponential phase of growth. Truncated derivatives of FnBPA, presenting either the fibrinogen-binding A domain or the fibronectin-binding BCD region, each promoted platelet activation when expressed on the surface of S. aureus or Lactococcus lactis, indicating two distinct mechanisms of activation. FnBPA-promoted platelet activation is mediated by fibrinogen and fibronectin bridges between the A domain and the BCD domains, respectively, to the low affinity form of the integrin GPIIb/IIIa on resting platelets. Antibodies recognizing the FnBPA A domain or the complex between the FnBPA BCD domains and fibronectin were essential for activation promoted by bacteria expressing the A domain or the BCD domain respectively. Activation was inhibited by a monoclonal antibody (IV-3) specific for the FcgammaRIIa IgG receptor on platelets. We propose that the activation of quiescent platelets by bacteria expressing FnBPs involves the formation of a bridge between the bacterial cell and the platelet surface by (i) fibronectin and fibrinogen interacting with the low affinity form of GPIIb/IIIa and (ii) by antibodies specific to FnBPs that engage the platelet Fc receptor FcgammaRIIa. Platelet activation by S. aureus clinical IE isolates from both the exponential and stationary phases of growth was completely inhibited by monoclonal antibody IV-3 suggesting that the IgG-FcgammaRIIa interaction is of fundamental importance for platelet activation mediated by this organism. This suggests new avenues for development of therapeutics against vascular infections.
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Affiliation(s)
- J Ross Fitzgerald
- Department of Microbiology, Moyne Institute of Preventive Medicine, University of Dublin, Trinity College, Dublin, Ireland
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Fish JM, Welchons DR, Kim YS, Lee SH, Ho WK, Antzelevitch C. Dimethyl lithospermate B, an extract of Danshen, suppresses arrhythmogenesis associated with the Brugada syndrome. Circulation 2006; 113:1393-400. [PMID: 16534004 PMCID: PMC1475954 DOI: 10.1161/circulationaha.105.601690] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Dimethyl lithospermate B (dmLSB) is an extract of Danshen, a traditional Chinese herbal remedy, which slows inactivation of INa, leading to increased inward current during the early phases of the action potential (AP). We hypothesized that this action would be antiarrhythmic in the setting of Brugada syndrome. METHODS AND RESULTS The Brugada syndrome phenotype was created in canine arterially perfused right ventricular wedge preparations with the use of either terfenadine or verapamil to inhibit INa and ICa or pinacidil to activate IK-ATP. AP recordings were simultaneously recorded from epicardial and endocardial sites together with an ECG. Terfenadine, verapamil, and pinacidil each induced all-or-none repolarization at some epicardial sites but not others, leading to ST-segment elevation as well as an increase in both epicardial and transmural dispersions of repolarization (EDR and TDR, respectively) from 12.9+/-9.6 to 107.0+/-54.8 ms and from 22.4+/-8.1 to 82.2+/-37.4 ms, respectively (P<0.05; n=9). Under these conditions, phase 2 reentry developed as the epicardial AP dome propagated from sites where it was maintained to sites at which it was lost, generating closely coupled extrasystoles and ventricular tachycardia and fibrillation. Addition of dmLSB (10 micromol/L) to the coronary perfusate restored the epicardial AP dome, reduced EDR and TDR to 12.4+/-18.1 and 24.4+/-26.7 ms, respectively (P<0.05; n=9), and abolished phase 2 reentry-induced extrasystoles and ventricular tachycardia and fibrillation in 9 of 9 preparations. CONCLUSIONS Our data suggest that dmLSB is effective in eliminating the arrhythmogenic substrate responsible for the Brugada syndrome and that it deserves further study as a pharmacological adjunct to implanted cardioverter/defibrillator usage.
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Affiliation(s)
- Jeffrey M Fish
- Masonic Medical Research Laboratory, Utica, NY 13501-1787, USA.
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Hauck CR, Ohlsen K. Sticky connections: extracellular matrix protein recognition and integrin-mediated cellular invasion by Staphylococcus aureus. Curr Opin Microbiol 2006; 9:5-11. [PMID: 16406780 DOI: 10.1016/j.mib.2005.12.002] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 12/15/2005] [Indexed: 10/25/2022]
Abstract
Staphylococcus aureus is a leading cause of hospital-acquired and often persistent infections. A key feature of pathogenic S. aureus is the expression of an array of extracellular matrix-binding proteins. In particular, the fibronectin-binding proteins FnBP-A and FnBP-B afford the pathogen the ability to connect to cellular integrins and to trigger internalization into host cells. Recent work has highlighted the role of host cell invasion in the pathogenesis of S. aureus, the structure-function relationship of FnBPs, and the host factors required to allow bacterial uptake. Understanding the invasive capacity of S. aureus should open up new avenues to control this microorganism in diverse disease settings.
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Affiliation(s)
- Christof R Hauck
- Zentrum für Infektionsforschung and Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, 97070 Würzburg, Germany.
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