Article révisé par les pairs
Résumé : In chronic liver disease, high circulating interleukin (IL)-6 contrasts with a poor acute phase response. We evaluated the impact of liver and circulating IL-6-receptor (IL-6R) forms on IL-6 bioactivity in chronic liver disease. IL-6, soluble IL-6-receptor and sgp130 levels were assayed in plasma from 45 patients with alcoholic liver disease, 84 with hepatitis C virus (HCV) infection undergoing transjugular liver biopsies and 15 healthy subjects. IL-6R mRNA was quantified on liver extracts from 54 patients with alcoholic liver disease with or without cirrhosis and 18 HCV-infected patients. The effect of gp130-Fc on fibrinogen secretion induced by IL-6 trans-signalling was evaluated on hepatocyte cultures. Levels of plasma IL-6 and sgp130, but not soluble IL-6R, increased with the stage of chronic liver disease, and correlated significantly with disease severity. Alcoholic liver disease patients had higher plasma IL-6 levels than hepatitis C, but lower liver IL-6R expression. In alcoholic and HCV-related liver diseases, liver IL-6R expression decreased with advanced fibrosis stage. In vitro, on hepatocytes, gp130-Fc blunted the acute phase response while soluble IL-6R enhanced IL-6 stimulation. In advanced chronic liver disease, high plasma IL-6 is associated with low liver IL-6R expression. This situation enables high plasma sgp130 to act as a major negative regulator of liver IL-6 trans-signalling, as demonstrated functionally here on hepatocytes. This might explain the poor acute phase response induced by IL-6 in chronic liver disease.

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