An overview of immunoregulatory roles of PD-1/PD-L1 in HCV treatment

As with high incidence of chronicity, hepatic fibrosis and hepatocellular carcinoma (HCC), hepatitis C virus (HCV) infection has become global problems of public hygiene. How to enhance the immunoregulatory ability of immunocytes turned out to be one of the key factors influencing the results of anti-HCV therapy. This review will summarize the survey of HCV infection and therapy, the association of PD-1 with anti-HCV immune response, and the roles of PD-1/PD-L1 blocking in anti-HCV. In chronic HCV patients, PD-1 level on dysfunctional HCV-specific CD8⁺ T cells was increased, and the virus-induced T cell dysfunction could be partly restored by PD-1/PD-L1 blocking. In HCV infection, the increased PD-1/PD-L1 inhibitory signal participates in the CTLs inhibition and CD8⁺T cell differentiation. It's also reported in clinically that anti-HCV immune response could be enhanced by PD-1/PD-L1 blocking. Therefore, it's of great importance to explore the mechanisms of HCV-induced PD-1 increasing and PD-1/PD-L1 inhibitory signal induced T cell dysfunction, which will contribute to the prophylactic and therapeutic vaccines for HCV infection, and lastly better HCV therapy.