Tifacogin and a synthetic TFPI peptide fragment suppress cytokine production due to Streptococcus pneumoniae and Staphylococcus aureus in whole blood cultures
Abstract number: P950
Dai Y., Schirm S., Liu X., Hardy S.
Objective: Tifacogin, rTFPI, has demonstrated efficacy in acute inflammation after Escherichia coli infection in several animal models of severe sepsis. Tifacogin is currently being evaluated in a phase 3 clinical trial in severe community acquired pneumonia patients. Our goal was to investigate tifacogin activity in bacterially-induced inflammatory disease in an ex vivo model using disease relevant bacteria. The objective of this study was to investigate if cytokine production was reduced by tifacogin and TFPI-derived peptides in an ex vivo model of blood cultures inoculated with S. pneumoniae or S. aureus.
Methods: Tifacogin and synthetic C-terminal peptides derived from TFPI were prepared and their effect on inflammatory cytokine production in 10% human blood cultures containing Gram+ pathogens including S. pneumoniae and S. aureus were measured with and without vancomycin. For cytokine analysis, whole blood assay reactions were incubated for 1820 hours and cell-free supernatants were harvested. Aliquots were used in a custom pro-inflammatory human cytokine panel. Bacterial titers were measured by serial dilution of cultures, plating on appropriate agar and incubation overnight at 37°C.
Results: Addition of tifacogin to vancomycin reduced inflammatory cytokines IL-1B (7 pg/mL compared to 36 pg/mL for vancomycin alone), IL-6 (1100 pg/ml compared to 3450 pg/mL), TNF-a (37 pg/ml compared to 250 pg/mL), and IL-8 (3000 pg/mL compared to 25000 pg/mL) respectively compared to vancomycin alone. Similar changes were noted with other anticoagulants suggesting the effect was tied to clotting inhibition. In combination with vancomycin, a TFPI peptide but not its scrambled control also significantly reduced IL-6, IL-8 and TNF-a levels compared to vancomycin alone. The effects of tifacogin and TFPI peptide reinforced each other to lower cytokines to near baseline levels, suggesting different underlying mechanisms. Similar findings were noted when erythromycin was substituted for vancomycin.
Conclusions: Our results show that tifacogin and an rTFPI peptide demonstrate anti-inflammatory effects by reducing cytokine levels in blood inoculated with S. pneumoniae or S. aureus. These data suggest that tifacogin has antiinflammatory activity in addition to previously demonstrated anticoagulant activity. Tifacogin and rTFPI peptide fragment may have adjunctive antiinflammatory activity in combination with antibiotics.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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