The Heme oxygenase 1 product Biliverdin interferes with HCV replication by increasing anti-viral interferon response

Abstract

Background and Aims: The anti-apoptotic and hepatoprotective protein heme oxygenase-1 (HO-1) has been shown to interfere with replication of viruses, e.g. hepatitis B virus (HBV) and hepatitis C virus (HCV). Since HO-1 degrades heme to carbon monoxide (CO), iron and biliverdin, we investigated the effect of each product on HCV replication in vitro. Methods: HO-1 was induced using cobalt-protoporphyrin-IX (CoPP). Huh-5–15 cells, stably expressing HVC genes NS3 to NS5B, and LucUbiNeo-ET cells, containing additionally the firefly luciferase gene, were used to monitor HCV replication. Biliverdin was added in neutral solution. CO was provided by incubating cells in the presence of the CO donor methylene chloride (MC). To investigate the influence of iron on HCV replication, FeCL3, the iron donor lactoferrin or deferoxamine (DFO) were used. Real time RT-PCR for HO-1, antiviral interferons (IFN) alpha2 and alpha17, IFN-induced genes, e.g. oligoadenylate synthase (OAS) as well as protein kinase R (PKR) was performed. Results: The HO-1 product iron was not able to reduce HCV replication, while CO had a transient inhibitory effect. In contrast, incubation of replicon cells in the presence of biliverdin dose dependently and efficiently interfered with HCV replication in both assay systems, without displaying negative effects on cellular metabolism or cell proliferation. In cells incubated in the presence of biliverdin, anti-viral interferon expression as well as expression of IFN-induced genes was increased, while HO-1 expression was not induced. Conclusions: Inhibition of HCV replication seems to be mediated basically by the HO-1 product biliverdin. The underlying mechanism seems to be based on interference with oxidative stress, which is able to promote viral replication by down-regulation of anti-viral interferons. Biliverdin is well tolerated in vitro as well as in vivo. Further investigations are needed to validate the benefits of biliverdin treatment on HCV infection.