Combined inhibition of complement and CD14 attenuates bacteria-induced inflammation in human whole blood more efficiently than antagonizing the toll-like receptor 4-MD2 complex

Abstract

<i>Background</i>: Single inhibition of the Toll-like receptor 4 (TLR4)–MD2 complex failed in treatment of sepsis. CD14 is a coreceptor for several TLRs, including TLR4 and TLR2. The aim of this study was to investigate the effect of single TLR4-MD2 inhibition by using eritoran, compared with the effect of CD14 inhibition alone and combined with the C3 complement inhibitor compstatin (Cp40), on the bacteria-induced inflammatory response in human whole blood.<p>

<p><i>Methods</i>: Cytokines were measured by multiplex technology, and leukocyte activation markers CD11b and CD35 were measured by flow cytometry.<p>

<p><i>Results</i>: Lipopolysaccharide (LPS)–induced inflammatory markers were efficiently abolished by both anti-CD14 and eritoran. Anti-CD14 was significantly more effective than eritoran in inhibiting LPS-binding to HEK-293E cells transfected with CD14 and <i>Escherichia coli</i>–induced upregulation of monocyte activation markers (<i>P</i> < .01). Combining Cp40 with anti-CD14 was significantly more effective than combining Cp40 with eritoran in reducing <i>E. coli</i>–induced interleukin 6 (<i>P</i> < .05) and monocyte activation markers induced by both <i>E. coli</i> (<i>P</i> < .001) and <i>Staphylococcus aureus</i> (<i>P</i> < .01). Combining CP40 with anti-CD14 was more efficient than eritoran alone for 18 of 20 bacteria-induced inflammatory responses (mean <i>P</i> < .0001).<p>

<p><i>Conclusions</i>: Whole bacteria–induced inflammation was inhibited more efficiently by anti-CD14 than by eritoran, particularly when combined with complement inhibition. Combined CD14 and complement inhibition may prove a promising treatment strategy for bacterial sepsis.