Project description: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.

Project description:The woodchuck model of hepatitis B virus (HBV) infection displays many characteristics of human infection and has particular value for characterizing the host immune responses during the development of chronic infection. Using the newly developed custom woodchuck microarray platform, we compared the intrahepatic transcriptional responses of neonatal woodchucks with self-limiting and progressing persistent infection with woodchuck hepatitis virus (WHV). This revealed that WHV does not induce intrahepatic gene expression during the early acute stage of infection (8 weeks), suggesting it is a M-bM-^@M-^\stealthM-bM-^@M-^] virus. At the mid-acute phase of infection (14 weeks), resolution was associated with induction of a prominent cytotoxic T cell signature, with perforin and other markers of immune-mediated cytotolytic response being strongly expressed. Strikingly, this was accompanied by high level expression of PD-1 and various other inhibitory T cell receptors, which likely act to minimize liver damage by cytotoxic T cells during viral clearance. Conversely, self-limiting infection was not associated with a strong interferon-M-NM-1/M-NM-2 (IFN-M-NM-1/M-NM-2) transcriptional response, while the IFN-M-NM-3 signaling response (as measured by expression of CXCL9) in the mid-acute phase was comparable to that in chronically infected adult animals. Nevertheless, viperin and other antiviral genes were differentially expressed during resolving infection, suggesting that a subset of interferon-stimulated genes (ISGs) may play a role in the control of WHV replication. Conclusion: This study identifies new immune pathways associated with the clearance of hepadnavirus infection and reveals novel targets with potential for the treatment of chronic hepatitis B. Neonatal woodchucks of both genders were infected at 3 days of age with the same WHV7P1 inoculum containing 5 x 106 WID50 of WHV strain WHV7-11. Custom microarrays were generated from sequences obtained in transcriptome sequencing of woodchuck liver and PBMCs, and were used to examine liver gene expression in animals which eventually become chronically infected with WHV (8 weeks, n=5; 14 weeks, n=9), animals that eventually resolve WHV infection (8 weeks, n=10;14 weeks, n=7) and uninfected animals (8 weeks, n=5;14 weeks,n=5).

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Homo sapiens

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