Differential Expression of CX3CL1 in Hepatitis B Virus-Replicating Hepatoma Cells Can Affect the Migration Activity of CX3CR1 + Immune Cells

Abstract

ABSTRACT In addition to stellate cells and immune cells, inflamed hepatocytes and hepatoma cells express various kinds of chemokines that attract various kinds of immune cells. Previously, we reported that hepatitis B virus (HBV) replication can induce physiological stress. The aim of this study was to analyze the effect of chemokines produced by HBV-infected hepatocytes and hepatoma cells. A real-time PCR array targeting genes related to chemokines and enzyme-linked immunosorbent assay (ELISA) were carried out to detect the specific chemokines produced by Huh7 cells and HepG2 cells infected with various HBV genotypes. A migration assay, flow cytometry analysis, and immunohistochemistry were carried out to analyze the candidate immune cells that can affect the immunopathogenesis of HBV infection. The expressions of CX3CL1 mRNA and protein were significantly different among HBV genotypes A, B, and C and control cells (mock) ( P < 0.05). CD56 + NK cells and CD8 + T cells migrated to the hepatoma cells with HBV replication. Moreover, the migration activity of both immune cells was partially cancelled after the treatment of CX3CL1 neutralizing antibody. The expression level of NKG2D on CX3CR1 + NK cells in HCC with HBV infection was significantly lower than that in hepatocellular carcinoma (HCC) with HCV infection and chronic hepatitis B and C patients ( P < 0.05). On the other hand, the frequency of PD-1 high CX3CR1 + CD8 + T cells in HCC with HBV infection was significantly higher than that in HCC with HCV infection and chronic hepatitis B and C ( P < 0.05). The expression of CX3CL1 in HBV-replicating hepatocytes and hepatoma cells could contribute to the immunopathogenesis of HBV infection. IMPORTANCE The progressions of the disease are significantly different among HBV genotypes. However, it has not been clear that how different HBV genotypes could induce different inflammatory responses. Here, we first report that the levels of expression of CX3CL1 mRNA and protein were significantly different among HBV genotypes A, B, and C and mock. Not only the differential expression of CX3CL1 among the genotypes but also the phenotype of CX3CR1 + NK cells and T cells were gradually changed during the progression of the disease status. In addition to in vitro study, the analysis of immunohistochemistry with human samples and NOG mice with human lymphocytes and hepatoma cells supports this phenomenon. The quantification of CX3CL1 could contribute to better understanding of the disease status of HBV infection. Moreover, modifying CX3CL1 might induce an immune response appropriate to the disease status of HBV infection.