Sex differences in hepatitis C virus infection: characterisation of 17,β-estradiol-modulated antiviral defences in an HCV cell culture system

Chronic hepatitis C is one of the most widespread liver diseases in the world, with over 170 million individuals infected with the hepatitis C virus (HCV). Several clinical studies have observed a protective effect of female sex against HCV infection and HCV-related liver diseases. Our group have demonstrated that 17,β-estradiol (E2) is able to inhibit HCV life cycle in vitro but the antiviral mechanisms are still unknown. In the first part of the present study, we evaluated the E2-mediated activation of hepatocytes innate immunity. Several studies showed the relationship between hypoxia and E2 signaling pathway and the cellular hypoxic state appears to influence HCV infection and may play a significant role in viral hepatocarcinogenesis. In the second part of the study, we evaluated the relationship between HCV infection, hypoxia (induced by dimethyloxalylglycine (DMOG) treatment) and E2. We evaluated the persistence of the E2-mediated antiviral status after treatment removal and its impact on the infection susceptibility. The E2 antiviral activity loss resulted to be time-treatment dependent. Gene expression analysis of interferon-related genes was performed on E2-treated cells (w and w/o infection). We demonstrated that E2 up-regulate the innate immune gene transcription in naïve or infected cells. Also the conditioned medium (CM) produced by HuH7 cells post E2 treatment showed antiviral properties. Adding to E2 and CM treatment the an inhibitor of the IFN-α/IFNAR interaction, we obtained the complete antiviral effect loss; demonstrating that the E2-induced antiviral agents are linked to the interferon type I system. In the second part of the study, we found that the DMOG exerts opposite effects on viral infection, depending on exposure timing. Using the estrogen receptor (ER) agonist (E2) and antagonist (fulvestrant) compounds in combination with DMOG, we demonstrated a mutual interaction between the ER pathway and DMOG treatment effect on viral infection.