Hepatitis B Virus Causes Epigenetic Induction of Interleukin-8Production which in Turn Inhibits Interferon-alfa Antiviral Activity

Background: Serum interleukin-8 (IL-8) concentrations are increased in chronic hepatitis B (CHB) patients during hepatic flares. Aims of this study were: (1) to determine IL-8 amounts in sera and liver tissues of CHB patients, inactive HBV carriers (IBC) and healthy controls (HC), (2) to analyse the mechanisms implicated in HBV-induced IL-8 gene expression, (3) to study the possible antagonistic activity of IL-8 on INFá-treatment response. Methods: Serum IL-8 amounts were analysed by an ELISA assay. IL-8 mRNA quantification in liver tissues and HBV-replicating cells was performed by real-time PCR. An IL-8 promoter-driven luciferase assay was used to study IL-8 promoter transactivation. The ChIP-assay was applied to analyse IL-8 promoter acetylatilatio/methylation status. A cell-based HBV replication system was used to test the potential antagonistic effect of IL-8 on INFá-treatment response. Results: CHB patients had higher amounts of IL-8 both in serum and liver tissue compared to controls. In HBV-replicating cells, IL-8 promoter transcriptional activity was stimulated up to 100-fold and IL-8 transcription was significantly increased. The luciferase-reporter-assay showed that NFkB and AP-1 are essential for IL-8 induction by HBV. HBx viral protein was recruited onto the IL-8 promoter. Acetylation/methylation status of IL-8 promoter was strongly correlated with IL-8 amounts both in serum and liver tissue. Inhibition of IL-8 by anti-IL8 monoclonal antibodies or IL8-siRNA increased IFN-alfa inhibitory action on HBV replication in transfected cells. Conclusions: (1) Highly replicating HBV is able to induce IL-8 transcription by targeting the epigenetic regulation of IL-8 promoter. (2) The induction of IL-8 by HBV inhibits the INFalpha antiviral activity.