Phagocytosis of live and dead Escherichia coli and Staphylococcus aureus in human whole blood is markedly reduced by combined inhibition of C5aR1 and CD14
AuthorSkjeflo, Espen Waage; Christiansen, Dorte; Landsem, Anne; Stenvik, Jørgen; Woodruff, T. M.; Espevik, Terje; Nielsen, Erik Waage; Mollnes, Tom Eirik
Methods - Lepirudin-anticoagulated blood was incubated with live or dead E. coli or S. aureus at 37 °C for 120 min with or without the C5aR1 antagonist PMX53 and/or anti-CD14. Granulocyte and monocyte phagocytosis were measured by flow cytometry, and five plasma cytokines by multiplex, yielding a total of 28 mediators of inflammation tested for.
Results - 16/28 conditions were reduced by PMX53, 7/28 by anti-CD14, and 24/28 by combined PMX53 and CD14 inhibition. The effect of complement inhibition was quantitatively more pronounced, in particular for the responses to S. aureus. The effect of anti-CD14 was modest, except for a marked reduction in INF-β. The responses to live and dead S. aureus were equally inhibited, whereas the responses to live E. coli were inhibited less than those to dead E. coli.
Conclusion - C5aR1 inhibited phagocytosis-induced inflammation by live and dead E. coli and S. aureus. CD14 blockade potentiated the effect of C5aR1 blockade, thus attenuating inflammation.