The Regulatory Role And Mechanism Of Hepatitis C Virus On The Production Of Myeloid-derived Suppressor Cells In Peripheral Blood Mononuclear Cells

Background Hepatitis C virus(HCV) infection is one of the serious social and public health problem in the world. In acute HCV infection, about 80% of the population will become chronic hepatitis C, and eventually develop into cirrhosis and liver cancer. The mechanism of chronicity and escaping from the host immune clearance has been a hotspot and difficulty. Chronic HCV infection is related to low or absent cellular or humoral immune function, causing the body can not effectively remove the virus, resulting in chronic infection, especially T cell dysfunction plays an important role in chronic HCV infection. Myeloid-derived suppressor cells(MDSCs) are heterogeneous group of immune cells from the myeloid lineage with the function of inhibiting T cell response. At present, the researches on MDSCs are mainly focused on the tumor, which is related to the invasion, metastasis and long-term prognosis of the tumor. Moreover, MDSCs is considered to play an important role in tumor escape from immune surveillance. The researches on mechanism of MDSCs have also focused on its inhibition of T cell function. Studies on the correlation between MDSCs and HCV infection are few, and the conclusions are controversial. Whether and how HCV induces MDSCs production are unclear. Therefore, this study is to investigate whether HCV could induce MDSCs from peripheral blood mononuclear cells(PBMCs), as well as the mechanism of induction. Provide an important theoretical basis for elucidating the mechanism of chronic HCV infection, targeting MDSCs may open a new treatment of HCV persistent infection.Objective 1. To study whether HCV could induce MDSCs from PBMCs; 2. To explore mechanisms of HCV regulating MDSCs production.Contents and Methods 1. Through immunomagnetic sorting method, we isolated fresh CD14+ PBMCs from peripheral blood concentrated lymphocytes of healthy donors, HCV core protein(HCVc) and polyinosinic:polycytodylic acid(poly I:C) simulated HCV infection and treated CD14+ PBMCs. Peripheral blood concentrated lymphocytes were from Changchun Blood Center. 2. Identification of MDSCs. Using flow cytometry(FCM) to detect cell phenotypes, real-time quantitative polymerase chain reaction(RT-PCR) to find the expression of related genes(Arg-1, i NOS, IDO), enzyme-linked immunosorbent assay(ELISA) to test the secretion of IFN-γ, T cell proliferation assay to show T cell proliferation. 3. Study on the mechanism of HCV regulating MDSCs production. Neutralizing antibody(Anti-Human IL-1β, IL-10, TNF-α, IFN-β, IFN-α) and pathway inhibitors(PI3-Kinase Inhibitor, PI3Ki) treated CD14+ PBMCs. The related detections were performed by FCM, ELISA and RT-PCR.Results 1. HCV induces and regulates the production of MDSCs. CD14+ PBMCs treated with HCVc developed a CD14+HLADR-/low phenotype with up-regulated expression of IDO, and suppress T-cell proliferation. We successfully induced MDSCs production from PBMCs. We also found that poly I:C inhibits the production of MDSCs induced by HCVc. Therefore, HCV can regulate the production of MDSCs in PBMCs. 2. HCV regulates MDSCs production through PI3 K pathway and autocrine cytokines. HCVc induces the production of IL-10 and TNF-α by activating the PI3 K pathway, which promotes the production of MDSCs. Poly I:C induces the secretion of type I interferon by activating the PI3 K pathway, which inhibits the production of MDSCs induced by HCVc. 3. IL-10 plays a central regulatory role in autocrine cytokines. HCVc and poly I:C induce the secretion of TNF-α, IL-1β, IL-10 and typeⅠinterferon by PI3 K pathway. Among these cytokines, TNF-α and IL-1β promote the production of IL-10, then IL-10 inhibits the secretion of type I interferon. In turn, type I interferon promotes the secretion of IL-10, subsequently IL-10 inhibits TNF-α and IL-1β to produce. Therefore, form a regulatory network, and IL-10 plays a central regulatory role.Conclusions HCVc could induce the production of MDSCs from PBMCs, but poly I:C inhibits the induction of HCVc. HCV via PI3 K signaling pathway and autocrine cytokines to regulate MDSCs production. Among these autocrine cytokines, IL-10 play a central regulatory role.