Phagocytosis of live and dead Escherichia coli and Staphylococcus aureus in human whole blood is markedly reduced by combined inhibition of C5aR1 and CD14

BACKGROUND: Sepsis is a dysregulated host response to infection. The aim of this study was to investigate the effects of complement- and CD14 inhibition on phagocytosis of live and dead Gram-negative and Gram-positive bacteria in human whole blood. 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.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

In lepirudin-anticoagulated human whole blood challenged with E. coli or S. aureus, combined inhibition of C5aR1 and CD14 reduced 24 of 28 measured inflammatory mediators, more than either inhibitor alone, with C5aR1 inhibition's effect more pronounced than CD14's, particularly for S. aureus.

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