Inhibition of IκB kinase by thalidomide increases hepatitis C virus RNA replication

. Hepatic fibrosis is an integral element in the progression of chronic liver disease. Elevated hepatic interleukin (IL)-8 is an important contributor to fibrosis in patients chronically infected with the hepatitis C virus (HCV). Thalidomide has been used to reduce liver inflammation and fibrosis in HCV-infected patients, but its impact on HCV replication remains unclear. This study examined the effect of thalidomide on HCV replication in vitro. Results revealed that while thalidomide reduced IL-8 and nuclear factor kappa B (NF-?B) activity by 95% and 46% in Huh-7 cells, increasing concentrations of thalidomide correlated with a linear rise in HCV replication (17-fold at 200 mu m). The NF-?B inhibitors, wedelolactone and NF-B activation inhibitor-1, which mimic the actions of thalidomide by preventing phosphorylation and activation of I?B kinase (IKK) and hence block NF-B activity, increased HCV RNA by 18- and 19-fold, respectively. During in vitro HCV replication in Huh-7 cells, we observed a 30% increase in IKKa protein and 55% decrease in NF-B(p65)/RelA protein relative to cellular beta-actin. Ectopic expression of IKKa to enhance the inactive form of IKK in cells undergoing virus replication led to a 13-fold increase in HCV RNA. Conversely, enhanced expression of NF-B(p65)/RelA in infected cells resulted in a 17-fold reduction in HCV RNA. In conclusion, HCV RNA replication was significantly augmented by the inhibition of IKK activation and subsequent NF-B signalling, whereas a restoration of NF-?B activity by the addition of NF-B/RelA markedly reduced HCV replication. This study lends added importance to the role of the NF-?B signalling pathway in controlling HCV replication.