Ethanol-mediated stimulation of HCV replication in vitro: Role of MAP Kinase activity and generation of radical oxygen species

Aims: In chronic hepatitis C the natural course of the disease is more aggressive in alcoholics and leads earlier to liver cirrhosis. Furthermore, the sustained virological reponse upon interferon therapy is diminished in alcoholics.

Aim: To clarify the effect of ethanol on viral replication in the replicon system.

Methods: All experiments were done in the replicon system. We used a replicon with a stably replicating subgenomic HCV RNA which also carries the firefly luciferase as an reporter gene. The replicon was stimulated with different concentrations of ethanol and modulated by MAP kinase inhibitors (SB 203580, UO 126), proteasome inhibitor (MG 132) or n-acetycystein. The change in replication was measured 72 hours after stimulation with a luciferase assay. Proliferation was determined by the MTT-assay.

Results: Ethanol increased HCV replication in a dose dependent manner about 40%. Ethanol had no effect on the inhibitory action of interferon. Inhibition of the p38 MAP Kinase suppressed the ethanol effect about 50%. Acetylcystein diminished ethanol action about 35%. Interestingly, inhibition of p42/p44 MAPK augmented the replication about 20%, without a synergystic effect of ethanol. MG 132 suppressed replication of HCV about 65% without an antagonistic effect of ethanol. Proliferation was unchanged under this condition.

Conclusion: Ethanol increases the replication of HCV, potentially involving p38-MAPK activity and generation of radical oxygen species. p42/p44-MAPK activity and proteasome function could be important targets for inhibition of HCV replication.

Keywords: Alkohol, Hepatitis C, Replikon