Impaired interferon type I signalling in the liver modulates the hepatic acute phase response in hepatitis C virus...

The immunomodulatory active hepatitis C virus (HCV) has been shown to interfere with antiviral interferon (IFN) type I functions. The aim of the study was to determine whether further basic innate immunologic functions are influenced by HCV.

The acute phase response (APR) was induced in HCV transgenic (tg) mice and C57BL/6J control mice using lipopolysaccharide. Activation of transcription factors, mRNA expression and production of cytokines and acute phase proteins (APP) were determined. IFN type I and tumor necrosis factor (TNF) alpha signalling were investigated after polyI:C or TNF-alpha treatment.

HCV tg mice showed an attenuated APR: hepatic activation of nuclear factor kappa B (NFkappaB) and interferon-stimulated gene factor 3 (ISGF3), hepatic expression of interleukin (IL) 6, IL-10, and IFN-gamma mRNA, serum concentrations of IL-6 and IFN-gamma and production of type II acute phase proteins were reduced compared to wild-type mice. While no differences in NFkappaB activation could be detected after TNF-alpha injection, HCV tg mice showed reduced activation of ISGF3 and reduced transactivation of IFN target genes after polyI:C treatment.

Besides antiviral defence mechanisms, interruption of IFN type I signalling by HCV modulates the APR which is aimed at a variety of pathogens.