Phagocytosis of live and dead Escherichia coli and Staphylococcus aureus in human whole blood is markedly reduced by combined inhibition of C5aR1 and CD14. (August 2019)

• Record Type: Journal Article
• Authors: Skjeflo, E.W.; Christiansen, D.; Landsem, A.; Stenvik, J.; Woodruff, T.M.; Espevik, T.; Nielsen, E.W.; Mollnes, T.E.
• Is Part Of: Molecular immunology. Volume 112(2019:Aug.)
• Page Start: 131
• Page End: 139
• Publication Date: 2019-08
• Subjects: Complement -- Toll-like receptors -- Bacteremia -- Inflammation -- Innate immune response -- Phagocytosis; Immunochemistry -- Periodicals; Molecular biology -- Periodicals; Immunochemistry -- Periodicals; Allergy and Immunology -- Periodicals; Molecular Biology -- Periodicals; Immunochimie -- Périodiques; Biologie moléculaire -- Périodiques; Immunochemistry; Molecular biology; Periodicals; Electronic journals; 571.96
• DOI: 10.1016/j.molimm.2019.03.014
• Languages: English
• ISSNs: 0161-5890

Abstract

Highlights: Blocking C5aR1 and CD14 reduced phagocytosis and cytokine release in response to S. aureus and E. coli over time in blood. The effect ofPMX-53 was potentiated by combined CD14 inhibition. C5aR1 and CD14 seem attractive targets for inhibition of phagocytosis-induced inflammation induced by S. aureus and E. coli: Opsonisation of microbes by C3 and the lytic C5b-9 pathway are preserved. C5a-mediated pro-inflammatory responses are prevented. Abstract: 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.