Intrahepatic Transcriptional Signature Associated with Response to Interferon-α Treatment in the Woodchuck Model of Chronic Hepatitis B.

Simon P Fletcher,Jade Carter,David C Swinney,Daniel J Chin,Miriam Triyatni,Erik Rasmussen,Junming Yang,Fabian Birzele,Erhard Kopetzki,Roland Schmucki,Lore Gruenbaum,Palanikumar Ravindran,Stephan Menne,Dalal Aldeghaither,Hans Bitter,Paul J Côté ,Marta G Murreddu ,Linta Thampi ,Stefan Lorenz

doi:10.1371/journal.ppat.1005103

Abstract

Recombinant interferon-alpha (IFN-α) is an approved therapy for chronic hepatitis B (CHB), but the molecular basis of treatment response remains to be determined. The woodchuck model of chronic hepatitis B virus (HBV) infection displays many characteristics of human disease and has been extensively used to evaluate antiviral therapeutics. In this study, woodchucks with chronic woodchuck hepatitis virus (WHV) infection were treated with recombinant woodchuck IFN-α (wIFN-α) or placebo (n = 12/group) for 15 weeks. Treatment with wIFN-α strongly reduced viral markers in the serum and liver in a subset of animals, with viral rebound typically being observed following cessation of treatment. To define the intrahepatic cellular and molecular characteristics of the antiviral response to wIFN-α, we characterized the transcriptional profiles of liver biopsies taken from animals (n = 8–12/group) at various times during the study. Unexpectedly, this revealed that the antiviral response to treatment did not correlate with intrahepatic induction of the majority of IFN-stimulated genes (ISGs) by wIFN-α. Instead, treatment response was associated with the induction of an NK/T cell signature in the liver, as well as an intrahepatic IFN-γ transcriptional response and elevation of liver injury biomarkers. Collectively, these data suggest that NK/T cell cytolytic and non-cytolytic mechanisms mediate the antiviral response to wIFN-α treatment. In summary, by studying recombinant IFN-α in a fully immunocompetent animal model of CHB, we determined that the immunomodulatory effects, but not the direct antiviral activity, of this pleiotropic cytokine are most closely correlated with treatment response. This has important implications for the rational design of new therapeutics for the treatment of CHB.

Highlights

250 million individuals live with chronic hepatitis B (CHB), and over half a million people are estimated to die each year due to CHB-associated liver diseases, such as cirrhosis and hepatocellular carcinoma (HCC) [1]
250 million people are chronically infected with hepatitis B virus (HBV), and over 500,000 people die every year because of associated liver diseases
We found that the treatment response did not correlate with the expression of antiviral effector genes that have previously been shown to mediate the direct antiviral effects of IFN-α in vitro

Summary

Introduction

250 million individuals live with chronic hepatitis B (CHB), and over half a million people are estimated to die each year due to CHB-associated liver diseases, such as cirrhosis and hepatocellular carcinoma (HCC) [1]. End-points of therapies for CHB are virological response (durable reduction in serum HBV DNA levels to a degree which varies by therapy), serological response (HBV e antigen (HBeAg) loss and seroconversion to anti-HBe in HBeAg-positive patients) and biochemical response (normalization of ALT levels). Sustained loss of HBV surface antigen (HBsAg) off therapy is currently considered the ideal end-point. Recombinant interferon-α (IFN-α) is licensed for the treatment of CHB, but in contrast to potent nucleos(t)ides, virologic response is limited to a subset of patients [2]. The rate of durable HBsAg loss is higher with IFN-α than with nucleos(t)ides, still only occurs in

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