thromboplastin and Staphylococcal-Infections

Although streptococcal and S. aureus IE share the same primary site of infection, their pathogenesis and clinical evolution present several major differences. Streptococci adhere to cardiac valves with pre-existing endothelial lesions. In contrast, S. aureus can colonize either damaged endothelium or invade physically intact endothelial cells. These interactions are mediated by multiple surface adhesins, some of which have been only partially characterized. Streptococci produce surface glucans (gtf and ftf), ECM adhesins (e.g., fibronectin-binding proteins, FimA), and platelet aggregating factors (phase I and phase II antigens, pblA, pblB, and pblT), all of which have been.

Topics: Adhesins, Bacterial; Antigens, Surface; Bacterial Proteins; Blood Platelets; Endocarditis, Bacterial; Extracellular Matrix; Heart Valves; Humans; Staphylococcal Infections; Staphylococcus; Streptococcal Infections; Streptococcus; Thromboplastin

TFPI-tissue factor pathway inhibitor appears to play a primary role in regulating TF-induced coagulation. During CAPD procoagulant and anticoagulant activities of the mesothelium are balanced under normal conditions. The aim of the work was to assess TF and TFPI concentrations during peritonitis in CAPD patients. The study was performed in 9 CAPD subjects with peritonitis and 14 clinically stable CAPD patients. TF, total, free and truncated TFPI, thrombomodulin concentrations were measured in plasma and dialysate; C-reactive protein and tumor necrosis factor-TNF alpha were assayed in serum. In 8 patients with S. aureus peritonitis TF and TFPI were not found in dialysate, but were detectable in a case with E. coli peritonitis. C-reactive protein and TNF alpha significantly elevated at the beginning of peritonitis, fell sharply after the therapy. Further studies are needed to establish whether the kind of bacterial peritonitis (Gram-positive or negative) may affect TF and TFPI in plasma and dialysate in CAPD patients.

Topics: Adult; Aged; Anticoagulants; Bacterial Infections; C-Reactive Protein; Dialysis Solutions; Humans; Lipoproteins; Middle Aged; Peritoneal Dialysis, Continuous Ambulatory; Peritonitis; Staphylococcal Infections; Thrombomodulin; Thromboplastin; Tumor Necrosis Factor-alpha

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Blood Coagulation; Coagulase; Female; Fibrin; Fibrinogen; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Peritonitis; Prothrombin; Staphylococcal Infections; Staphylococcus aureus; Thromboplastin

Essentials Complement, Toll-like receptors and coagulation cross-talk in the process of thromboinflammation. This is explored in a unique human whole-blood model of S. aureus bacteremia. Coagulation is here shown as a downstream event of C5a-induced tissue factor (TF) production. Combined inhibition of C5 and CD14 efficiently attenuated TF and coagulation.. Background There is extensive cross-talk between the complement system, the Toll-like receptors (TLRs), and hemostasis. Consumptive coagulopathy is a hallmark of sepsis, and is often mediated through increased tissue factor (TF) expression. Objectives To study the relative roles of complement, TLRs and TF in Staphylococcus aureus-induced coagulation. Methods Lepirudin-anticoagulated human whole blood was incubated with the three S. aureus strains Cowan, Wood, and Newman. C3 was inhibited with compstatin, C5 with eculizumab, C5a receptor 1 (C5aR1) and activated factor XII with peptide inhibitors, CD14, TLR2 and TF with neutralizing antibodies, and TLR4 with eritoran. Complement activation was measured by ELISA. Coagulation was measured according to prothrombin fragment 1 + 2 (PTF

Topics: Antibodies, Neutralizing; Bacteremia; Bacterial Load; Blood Coagulation; Complement Activation; Complement C5a; Complement Inactivating Agents; Host-Pathogen Interactions; Humans; Lipopolysaccharide Receptors; Microbial Viability; Monocytes; Receptor, Anaphylatoxin C5a; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus; Thromboplastin; Time Factors; Toll-Like Receptor 2

The key effector molecule of the natural protein C pathway, activated protein C (aPC), exerts pleiotropic effects on coagulation, fibrinolysis, and inflammation. Coagulation-independent cell signaling by aPC appears to be the predominant mechanism underlying its highly reproducible therapeutic efficacy in most animal models of injury and infection. In this study, using a mouse model of Staphylococcus aureus sepsis, we demonstrate marked disease stage-specific effects of the anticoagulant and cell signaling functions of aPC. aPC resistance of factor (f)V due to the R506Q Leiden mutation protected against detrimental anticoagulant effects of aPC therapy but also abrogated the anti-inflammatory and mortality-reducing effects of the signaling-selective 5A-aPC variant that has minimal anticoagulant function. We found that procofactor V (cleaved by aPC at R506) and protein S were necessary cofactors for the aPC-mediated inhibition of inflammatory tissue-factor signaling. The anti-inflammatory cofactor function of fV involved the same structural features that govern its cofactor function for the anticoagulant effects of aPC, yet its anti-inflammatory activities did not involve proteolysis of activated coagulation factors Va and VIIIa. These findings reveal a novel biological function and mechanism of the protein C pathway in which protein S and the aPC-cleaved form of fV are cofactors for anti-inflammatory cell signaling by aPC in the context of endotoxemia and infection.

Topics: Animals; Factor V; Mice; Mice, Transgenic; Protein C; Protein S; Sepsis; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus; Thromboplastin

Topics: Animals; Factor V; Protein C; Sepsis; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus; Thromboplastin

During severe sepsis, microvesicles that are positive for tissue factor (TF) are at increased levels within blood and in pulmonary lavage. These microvesicles potentially disperse TF, the major initiator of the coagulation cascade, throughout multiple organ systems, initiating fibrin deposition and resultant ischemia. The source of these microvesicles has remained incompletely defined. Although TF(+) microvesicles are shed from cells that express nascent TF transcript in response to injury, recent findings revealed that circulating, full-length TF protein is detectable prior to these nascent transcripts. This finding suggested that the protein is released from constitutive sources as an acute response. We examined whether Staphylococcus aureus, the Gram-positive bacteria that is emerging as one of the most common etiologic agents in sepsis, is capable of stimulating the release of TF(+) microvesicles from a pulmonary cell line that constitutively expresses TF protein. We found that host cell invasion stimulated an acute release of TF(+) microvesicles and that these microvesicles mediated the transfer of the protein to TF-negative endothelial cells. We also found that transfer was inhibited by cholesterol-lowering simvastatin. Taken together, our findings reveal that S. aureus pathogenesis extends to the acute release of TF(+) microvesicles and that inhibiting dispersal by this mechanism may provide a therapeutic target.

Topics: Cell Line; Cytoplasmic Vesicles; Host-Pathogen Interactions; Humans; Lung; Protein Transport; Sepsis; Simvastatin; Staphylococcal Infections; Staphylococcus aureus; Thromboplastin

The Staphylococcus aureus fibronectin (Fn) -binding protein A (FnBPA) is involved in bacterium-endothelium interactions which is one of the crucial events leading to infective endocarditis (IE). We previously showed that the sole expression of S. aureus FnBPA was sufficient to confer to non-invasive Lactococcus lactis bacteria the capacity to invade human endothelial cells (ECs) and to launch the typical endothelial proinflammatory and procoagulant responses that characterize IE. In the present study we further questioned whether these bacterium-EC interactions could be reproduced by single or combined FnBPA sub-domains (A, B, C or D) using a large library of truncated FnBPA constructs expressed in L. lactis. Significant invasion of cultured ECs was found for L. lactis expressing the FnBPA subdomains CD (aa 604-877) or A4(+16) (aa 432-559). Moreover, this correlates with the capacity of these fragments to elicit in vitro a marked increase in EC surface expression of both ICAM-1 and VCAM-1 and secretion of the CXCL8 chemokine and finally to induce a tissue factor-dependent endothelial coagulation response. We thus conclude that (sub)domains of the staphylococcal FnBPA molecule that express Fn-binding modules, alone or in combination, are sufficient to evoke an endothelial proinflammatory as well as a procoagulant response and thus account for IE severity.

Topics: Adhesins, Bacterial; Cells, Cultured; Endothelial Cells; Fibronectins; Humans; Lactococcus lactis; Mutant Proteins; Staphylococcal Infections; Staphylococcus aureus; Thromboplastin

Sepsis-induced abnormalities of coagulation may contribute to mortality during severe bacterial infection. The aim of this study was to examine changes in coagulation parameters and to assess the role of protein C supplementation during murine S. aureus sepsis. Gram-positive sepsis was characterized by a hypercoagulable state with predominant activation of the external coagulation pathway, registered as an early increase of tissue factor activity and concomitant reduction in protein C. The internal coagulation pathway was unaffected. No correlation between the changes of coagulation parameters and the intensity of inflammation, determined as serum IL-6 levels, was found. Supplementation with neither protein C or APC favoured survival in S. aureus sepsis. Reduction in thrombin generation in response to protein C supplementation was associated with significantly increased survival.

Topics: Animals; Anticoagulants; Bacteremia; Blood Coagulation; Blood Coagulation Factors; Interleukin-6; Mice; Protein C; Staphylococcal Infections; Staphylococcus aureus; Thrombin; Thromboplastin

In vitro infection of cultured human cardiac valve endothelium (HCVE) with Staphylococcus aureus was used as a model to study potential mechanisms of vegetation formation in infective endocarditis. S. aureus was observed to adhere to and be ingested by HCVE. Infection for 8 h resulted in increased levels of procoagulant activity in HCVE, shown to be tissue factor by a specific assay. Mean activity in infected HCVE was 662 +/- 149 (mU/10(5) HCVE +/- 1 SD) versus 221 +/- 78 in control HCVE; surface-expressed activity was 57 +/- 25 in infected monolayers and undetectable (less than or equal to 10) in controls. Bacteria alone had no activity. These results suggest that endothelium may have a functional role in the pathogenesis of S. aureus endocarditis and may provide one potential mechanism for activating coagulation to initiate vegetation formation on a colonized cardiac valve.

Topics: Cell Survival; Culture Techniques; Endocarditis; Endothelium; Heart Valves; Humans; Microscopy, Electron; Staphylococcal Infections; Thromboplastin; Time Factors