Gut-derived endotoxin stimulates factor VIII secretion from endothelial cells. Implications for hypercoagulability in cirrhosis

Background & Aims: Patients with cirrhosis display enhanced blood levels of factor VIII, which may result in harmful activation of the clotting system; however, the underlying mechanism is unknown. Methods: We performed a cross-sectional study in patients with cirrhosis (n = 61) and matched controls (n = 61) comparing blood levels of factor VIII, von Willebrand factor (vWf), lipopolysaccharide (LPS) and positivity for Escherichia coli DNA. Furthermore, we performed an in vitro study to investigate if LPS, in a concentration range similar to that found in the peripheral circulation of cirrhotic patients, was able to elicit factor VIII secretion from human umbilical vein endothelial cells (HUVEC). Results: Patients with cirrhosis displayed higher serum levels of LPS (55.8 [42.2–79.9] vs. 23.0 [7.0–34.0] pg/ml, p\0.001), factor VIII (172.0 [130.0–278.0] vs. 39.0 [26.0–47.0] U/dl, p\0.0001), vWf (265.0 [185.0–366.0] vs. 57.0 [48.0–65.0] U/dl, p\0.001) and positivity for Escherichia coli DNA (88% vs. 3%, p\0.001, n = 34) compared to controls. Serum LPS correlated significantly with factor VIII (r = 0.80, p\0.001) and vWf (r = 0.63, p\0.001). Only LPS (beta-coefficient = 0.70, p\0.0001) independently predicted factor VIII levels. The in vitro study showed that LPS provoked factor VIII and vWf release from HUVEC via formation and secretion of Weibel-Palade bodies, a phenomenon blunted by pre-treating HUVEC with an inhibitor of Toll-like receptor 4. Conclusions: The study provides the first evidence that LPS derived from gut microbiota increases the systemic levels of factor VIII via stimulating its release by endothelial cells.