4 research outputs found
The effect of combined inhibition of C5aR1 and CD14 on phagocytosis of E. coli in human whole blood
The effect of combined inhibition of C5aR1 and CD14 on phagocytosis of E. coli in human whole blood
Complement C5 is essential for Escherichia coli-induced coagulation activation, independent of inhibition of cytokines inducing tissue factor
Complement component 5 does not interfere with physiological hemostasis but is essential for Escherichia coli-induced coagulation accompanied by Toll-like receptor 4.
There is a close crossâtalk between complement, Tollâlike receptors (TLRs) and coagulation. The role of the central complement component 5 (C5) in physiological and pathophysiological hemostasis has not, however, been fully elucidated. This study examined the effects of C5 in normal hemostasis and in Escherichia coliâinduced coagulation and tissue factor (TF) upâregulation. Fresh whole blood obtained from six healthy donors and one C5âdeficient individual (C5D) was antiâcoagulated with the thrombin inhibitor lepirudin. Blood was incubated with or without E. coli in the presence of the C5 inhibitor eculizumab, a blocking antiâCD14 monoclonal antibody (antiâCD14) or the TLRâ4 inhibitor eritoran. C5D blood was reconstituted with purified human C5. TF mRNA was measured by quantitative polymerase chain reaction (qPCR) and monocyte TF and CD11b surface expression by flow cytometry. Prothrombin fragment 1+2 (PTF1·2) in plasma and microparticles exposing TF (TFâMP) was measured by enzymeâlinked immunosorbent assay (ELISA). Coagulation kinetics were analyzed by rotational thromboelastometry and platelet function by PFAâ200. Normal blood with eculizumab as well as C5D blood with or without reconstitution with C5 displayed completely normal biochemical hemostatic patterns. In contrast, E. coliâinduced TF mRNA and TFâMP were significantly reduced by C5 inhibition. C5 inhibition combined with antiâCD14 or eritoran completely inhibited the E. coliâinduced monocyte TF, TFâMP and plasma PTF1·2. Addition of C5a alone did not induce TF expression on monocytes. In conclusion, C5 showed no impact on physiological hemostasis, but substantially contributed to E. coliâinduced procoagulant events, which were abolished by the combined inhibition of C5 and CD14 or TLRâ4.publishedVersion© 2018 The Authors. Clinical & Experimental Immunology published by John Wiley & Sons Ltd on behalf of British Society for Immunology This is an open access article under the terms of the Creative Commons AttributionâNonCommercial License