Gene expression profiling of primary human hepatocytes treated with IFN-alpha or IFN-gamma

Approximately 50% of patients with chronic hepatitis C (CHC) have a sustained virologic response (SVR) to treatment with pegylated interferon (pegINF)-α and ribavirin. Non-response to treatment is associated with constitutively increased expression of IFN-stimulated genes (ISGs) in the liver. Treatment of patients with acute hepatitis C (AHC) is more effective, with SVR rates >90%. We investigated mechanisms of the different responses of patients with CHC and AHC to pegIFN-α therapy. We analyzed IFN signaling and ISG expression in liver samples from patients with acute hepatitis C (AHC), patients with chronic hepatitis (CHC), and individuals without hepatitis C (controls) using microarray, immunohistochemical, and protein analyses. Findings were compared with those from primary human hepatocytes stimulated with IFN-α or IFN-γ, as reference sets. Expression levels of 100s of genes, primarily those regulated by IFN-γ, were altered in liver samples from patients with AHC compared with controls. Expression of IFN-γ–stimulated genes was induced in liver samples from patients with AHC, whereas expression of IFN-α–stimulated genes was induced in samples from patients with CHC. In an expression analysis of negative regulators of IFN-α signaling, we did not observe differences in expression of SOCS1 or SOCS3 between liver samples from patients with AHC and those with CHC. However, USP18 (another negative regulator of IFN-α signaling), was upregulated in liver samples of patients with CHC that did not respond to therapy, but not in AHC. In conclusion, differences in expression of ISGs might account for the greater response of patients with AHC, compared to those with CHC, to treatment with pegINF-α and ribavirin. Specifically, USP18 is upregulated in liver samples of patients with CHC that do not respond to therapy, but not in patients with AHC. (Interferon-γ Stimulated Genes, but not USP18, are Expressed in Livers of Patients with Acute Hepatitis C; Dill MT, Makowska Z et al, Gastroenterology 2012 (in press)) Primary human hepatocytes from 2 donors were analyzed. From each donor there are 5 samples: untreated cells, cells treated with interferon alpha (1000 IU/ml) for 6 and 24 hours and cells treated with interferon gamma (1000 IU/ml) for 6 and 24 hours.