HCV dsRNAActivated Macrophages Inhibit HCV Replication in Hepatocytes

Macrophages play critical roles in innate immune response in the liver. Whether macrophages participate in liver innate immunity against HCV replication is poorly understood The aim of this study was to investigate the role of macrophages in liver innate immunity against HCV replication. Freshly isolated monocytes were purified from peripheral blood of healthy adult donors. Macrophages refer to 7daycultured monocytes in vitro. A hepatoma cell line (Huh7) was infected with HCV JFH1 to generate in vitro HCV infectious system. RTPCR was used to determine HCV RNA and mRNA levels of genes expression. ELISA was used to measure the protein level of interferonα (IFNα) and western blot was used to determine protein expression level of Tolllike receptor 3 (TLR3). HCV dsRNA induced the expression of type I IFN (IFNα/β) in monocytederived macrophages. HCV dsRNA also induced the expression of TLR3 and IFN regulatory factor7 (IRF7), the key regulators of the IFN signaling pathway. When HCV JFH1infected Huh7 cells were cocultured with macrophages activated with HCV dsRNA or incubated in media conditioned with supernatant (SN) from HCV dsRNAactivated macrophages, HCV replication was significantly suppressed. This macrophage SN action on HCV inhibition was mediated through type I IFN, which was evidenced by the observation that antibody to type I IFN receptor could neutralize the macrophagesmediated antiHCV effect. The role of type I IFN in macrophagesmediated antiHCV activity is further supported by the observation that HCV dsRNAactivated macrophages SN treatment induced the expression of several IFNstimulated genes (ISGs), ISG15, ISG56, OAS1, OAS2, MxA and Viperin in HCVinfected Huh7 cells. Macrophages may play an important role in liver innate immunity against HCV replication through a type I IFNdependent mechanism.