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Oxidative stress inhibits IFN-alpha-induced antiviral gene expression by blocking the JAK-STAT pathway

Danilo Di Bona1, Marco Cippitelli, Cinzia Fionda

  • 1Cattedra e Unità Operativa di Gastroenterologia, Dipartimento Biomedico e di Medicina Specialistica, University of Palermo, Palermo, Italy. dibona@ibim.cnr.it

Journal of Hepatology
|April 6, 2006
PubMed
Abstract

Insights

Oxidative stress significantly impairs interferon-alpha (IFN-alpha) signaling by inhibiting key antiviral gene expression. This mechanism may explain why some chronic hepatitis C patients with high oxidative stress do not respond to IFN-alpha therapy.

Area of Science:

  • Hepatology
  • Virology
  • Molecular Biology

Background:

  • Unresponsiveness to interferon-alpha (IFN-alpha) is a significant challenge in treating chronic hepatitis C.
  • Conditions like advanced age, steatosis, fibrosis, iron overload, and alcohol consumption increase oxidative stress and are linked to reduced IFN-alpha response.

Purpose of the Study:

  • To investigate the hypothesis that oxidative stress negatively impacts the antiviral efficacy of IFN-alpha.
  • To elucidate the molecular mechanisms by which oxidative stress affects IFN-alpha signaling.

Main Methods:

  • Utilized a human hepatocellular carcinoma cell line (Huh-7) to model oxidative stress.
  • Exposed cells to hydrogen peroxide (H2O2) to induce oxidative stress and examined its effects on the IFN-alpha signaling pathway.

Main Results:

  • Hydrogen peroxide (H2O2) pretreatment suppressed IFN-alpha-induced expression of the antiviral protein MxA and IRF-9 mRNA.
  • H2O2 inhibited the IFN-alpha-induced assembly of signal transducer and activator of transcription (STAT) factors.
  • This inhibition occurred via preventing tyrosine phosphorylation of STAT-1 and STAT-2 by inactivating JAK-1 and Tyk-2, a rapid process not requiring protein synthesis.

Conclusions:

  • Oxidative stress demonstrably impairs IFN-alpha signaling pathways.
  • This impairment may contribute to resistance to IFN-alpha antiviral therapy in chronic hepatitis C patients with elevated liver oxidative stress.

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