LAUSR

background and purpose: Celastrol, a quinone methide triterpene isolated from the root extracts of Tripterygium wilfordii, can greatly induce the gene expression activity of heme oxygenase‐1 (HO‐1) to achieve disease prevention and control. HO‐1 induction was recently shown to result in anti‐HCV activity by inducing type I interferon and inhibiting hepatitis C virus (HCV) NS3/4A protease activity. The aim of the present study is to evaluate the anti‐HCV activity of celastrol and characterize its mechanism of inhibition. Methods: The anti‐HCV activity of celastrol was evaluated using the HCV subgenomic replicon and HCVcc infection systems. The anti‐HCV mechanism of celastrol targeting HO‐1 expression was clarified using specific inhibitors against several signaling pathways. The transcriptional regulation of celastrol on target gene expression was determined using promoter‐based reporter activity assay. The synergistic effect of celastrol and a numbers of clinically used anti‐HCV drugs was determined via a drug combination assay. Results: Celastrol inhibited HCV replication in both the HCV subgenomic and HCVcc infection systems with EC50 values of 0.37 ± 0.022 and 0.43 ± 0.019 &mgr;M, respectively. Celastrol‐induced heme oxygenase 1 (HO‐1) expression promoted antiviral interferon responses and inhibition of NS3/4A protease activity, thereby blocking HCV replication. These antiviral effects were abrogated by treatment with the HO‐1‐specific inhibitor SnMP or silencing of HO‐1 expression by transfection of shRNA, which indicates that HO‐1 induction contributes to the anti‐HCV activity of celastrol. JNK mitogen‐activated protein kinase and nuclear factor erythroid 2‐related factor 2 (Nrf2) were confirmed to be involved in the inductive effect of celastrol on HO‐1 expression. Celastrol exhibited synergistic effects in combination with interferon‐alpha, the NS5A inhibitor daclatasvir, and the NS5B inhibitor sofosbuvir. Conclusion: Celastrol can serve as a potential supplement for blocking HCV replication. Targeting the JNK/Nrf2/HO‐1 axis presents a promising strategy against HCV infection. Graphical abstract Figure. No Caption available. HighlightsCelastrol inhibits HCV replication.Celastrol induces HO‐1 production.Celastrol induces interferon‐&agr; production and inhibits HCV NS3/4A protease.Celastrol synergistically inhibits HCV replication in combination with IFN‐&agr;, sofosbuvir or daclatasvir.