The Role Of Plasmacytoid Dendritic Cells In Primary Hepatocellular Carcinoma

Plasmacytoid dendritic cells (pDCs) are known as type I interferon-producing cells, they are innate immune cells, represent0.2%-0.8%of peripheral blood mononuclear cells in humans. pDCs selectively express Toll-like receptor7(TLR7) and TLR9, they are specialized in rapid massive secretion of type I interferon in response to pathogenic agents or danger signals. Through the production of type I IFNs, pDCs initiate protective immunity by activating classical DCs, T cells, natural killer cells and B cells. Upon activation, pDCs differentiate into mature DCs. Combined with their antigen presentation capacity, this powerful functionality enables pDCs to orchestrate innate and adaptive immune responses. It has been demonstrated that pDCs can coordinate events during the course of viral infections and cancer. It is also reported that pDCs in peripheral blood from hepatocellular carcinoma patients numerically decreased and developmentally immature.Firstly, We took peripheral blood sample from patients with primary hepatocellular carcinoma, analyzed the number of pDCs by flow cytometry in peripheral blood mononuclear cells. Next, we analyzed the relationship between the number of pDCs and age, gender, hepatitis virus, Child-Pugh liver function classification, HCC pathologic differentiation, diameter of HCC, newly diagnosed and recurrent HCC, alpha-fetoprotein levels. We found that alpha-fetoprotein levels have significant impact on the number of pDCs, when alpha-fetoprotein concentration is greater than400μg/l, alpha-fetoprotein concentration dependently affected number of pDCs.Enriched pDCs from healthy human peripheral blood were incubated with alpha-fetoprotein, upon stimulated with CpG-ODN, alpha-fetoprotein suppresses production of IFN-a and cytokines production in pDCs, down-regulated CD80expression on pDCs, which indicated alpha-fetoprotein inhibited pDCs function at concentration dependent manner.Sorafenib is an multi-kinase inhibitor that showed antitumor activity in advanced hepatocellular carcinoma. It was reported that sorafenib have significant impact on the immune cell function. Enriched pDCs and PBMC from healthy human peripheral blood were incubated with sorafenib, upon stimulated with CpG-ODN,we found sorafenib suppressed production of IFN-a and cytokines production in enriched pDCs and PBMC, down-regulated costimulatory molecules express on pDCs. Meanwhile, sorafenib didn’t affect pDC survival in vitro. In addition, we analyzed the production of IFN-a in advanced hepatocellular carcinoma patients who were treated with sorafenib, IFN-a production significantly decreased in patients who were treated with sorafenib compared with hepatocellular carcinoma patients, but sorafenib did not have a significant impact on the number of pDCs in advanced hepatocellular carcinoma patients.We have demonstrated that sorafenib inhibited pDCs function in vivo and in vitro. In order to exploring the mechanisms of sorafenib inhibited pDCs function, GEN2.2cell were incubated with sorafenib, upon stimulated with CpG-ODN, sorafenib suppresses production of IFN-a and IL-6production in GEN2.2cell. By Western Blot analyzed, we found that sorafenib-mediated suppresses production of IFN-a in GEN2.2cell by inhibiting IRF7nuclear translocation.In summary, when alpha-fetoprotein concentration is greater than400ug/l,alpha-fetoprotein concentration dependently affected number of pDCs in vivo, alpha-fetoprotein concentration dependently inhibited pDCs fuction in vitro, sorafenib concentration dependently suppressed pDCs fuction in vivo and in vitro, we found that sorafenib-mediated suppresses production of IFN-a in GEN2.2cell by inhibiting IRF7nuclear translocation.