Xu Xiaodong, Yu Xiaojie, Deng Xiaozhao, Yue Ming, Zhang Jinhai, Zhu Danyan, Zhou Zhenxian, Zhai Xiangjun, Xu Ke, Zhang Yun
Department of Biochemistry and Molecular Biology, School of Basic Medicine, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.
School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu 210009, P.R. China.
Mol Med Rep. 2014 Feb;9(2):730-6. doi: 10.3892/mmr.2013.1816. Epub 2013 Nov 20.
The hepatitis C virus (HCV) alternate reading frame protein (ARFP or F protein) of the HCV 1b genotype is a double-frameshift product of the HCV core protein (Core). The discovery of HCV F protein challenges various biological functions attributed to Core. However, the specific characteristics of the host cellular immune response to F protein during HCV infection have yet to be fully elucidated. Therefore, the present study investigated the cytokine response to HCV Core or F protein in peripheral blood mononuclear cells (PBMCs) and plasmacytoid dendritic cells (PDCs) from patients with chronic HCV and healthy donors in vitro. The results demonstrated that the levels of interferon (IFN)-α, analyzed by an enzyme-linked immunosorbent assay, secreted by PBMCs in patients positive for the anti-F protein antibody, were lower than those of patients negative for the anti-F protein antibody. Moreover, the frequency of PDCs in patients negative for the anti-F protein antibody, were higher than in the group positive for the anti-F protein antibody. Furthermore, HCV F protein and Core not only inhibited specific unmethylated CpG oligonucleotide sequences of type A (CpG‑A)-induced IFN-α production by PBMCs and PDCs, but also upregulated the production of interleukin (IL)-10 by PBMCs in patients with chronic HCV and healthy controls. Notably, following neutralization of IL-10 in the media and in vitro Core or F protein stimulation, levels of IFN-α were increased. Moreover, the results revealed that the roles of F protein and Core were similar with regard to the induction of apoptosis of PDCs in patients with chronic HCV. These findings suggest that F protein may inhibit PBMC IFN-α secretion by regulating the production of IL-10, and may contribute to an increase in the rates of apoptosis in PDCs. In conclusion, the results have revealed a potential involvement of F protein in the mechanisms of chronic hepatitis C.
丙型肝炎病毒（HCV）1b基因型的丙型肝炎病毒交替阅读框蛋白（ARFP或F蛋白）是HCV核心蛋白（Core）的双移码产物。HCV F蛋白的发现对归因于Core的各种生物学功能提出了挑战。然而，HCV感染期间宿主细胞对F蛋白的免疫反应的具体特征尚未完全阐明。因此，本研究在体外调查了慢性HCV患者和健康供体的外周血单核细胞（PBMC）和浆细胞样树突状细胞（PDC）对HCV Core或F蛋白的细胞因子反应。结果表明，通过酶联免疫吸附测定分析，抗F蛋白抗体阳性患者的PBMC分泌的干扰素（IFN）-α水平低于抗F蛋白抗体阴性患者。此外，抗F蛋白抗体阴性患者的PDC频率高于抗F蛋白抗体阳性组。此外，HCV F蛋白和Core不仅抑制PBMC和PDC对A型特异性未甲基化CpG寡核苷酸序列（CpG-A）诱导的IFN-α产生，还上调慢性HCV患者和健康对照的PBMC产生白细胞介素（IL）-10。值得注意的是，在培养基中中和IL-10并进行体外Core或F蛋白刺激后，IFN-α水平升高。此外，结果显示F蛋白和Core在慢性HCV患者的PDC凋亡诱导方面作用相似。这些发现表明，F蛋白可能通过调节IL-10的产生来抑制PBMC IFN-α分泌，并可能导致PDC凋亡率增加。总之，结果揭示了F蛋白可能参与慢性丙型肝炎的发病机制。
