乙型肝炎病毒对干扰素-γ受体表达及其信号通路的影响

The influence of HBV on interferon gamma receptor 1 expression and its signal pathway

目的 探索乙型肝炎病毒 (HBV)持续存在和复制对干扰素 γ受体 (IFN γR)、IFN γ/STAT 1信号及MHC Ⅰ诱导表达的影响。方法 采用流式细胞术、Western blot及半定量逆转录 聚合酶链反应 (RT PCR)等方法 ,检测HepG2 .2 .15与HepG2肝母细胞瘤细胞株及人正常细胞株LO2的IFN γR表达 ;同时检测细胞IFN γR1对IFN γ的结合能力。观测不同时间段的IFN γ/p STAT1信号活化及IFN γ/MHC Ⅰ诱导效应。结果 HepG2 .2 .15细胞膜结合型及全细胞内IFN γR1表达高于其母源性细胞HepG2及正常肝细胞株LO2细胞 ;HepG2 .2 .15 细胞IFN γR1mRNA量显著高于HepG2及LO2细胞 (t=9.35 ,P <0 .0 1) ;HepG2 .2 .15 细胞全细胞IFN γR2表达低于HepG2及LO2细胞 ;两株肿瘤细胞存在内源性 p STAT1条带 ;HepG2 .2 .15细胞IFN γ/p STAT1、IFN γ/MHC Ⅰ诱导效应较母源细胞低下。拉米夫定抑制HBVDNA后 ,可上调HepG2 .2 .15细胞的IFN γ/MHC Ⅰ表达。结论 HBV持续存在和复制可降低IFN γ/STAT1及IFN γ/MHC Ⅰ诱导表达的敏感性 ;并能上调IFN γR1表达、下调IFN γR2表达。

Objective To investigate whether hepatitis B virus will influence interferon gamma receptor expression and IFN γ/STAT1 signal of the target cells. Methods Two human hepatoblastoma cell lines, HepG2 and its HBV whole genome transgenic cell line named HepG2.2.15,as well as normal liver cell line LO2, were used in the experiments. Expression of interferon gamma receptor 1 was determined by flow cytometry and Western blots. The expression of the mRNA of interferon gamma receptor 1 was also assessed by semi quantitive RT PCR. The integrity of the interferon gamma siganal pathways was determined by Western blot to assess phosphorylated signal transducer and activator of transcription STAT1 and by flow cytometry to investigate the up regulation of MHC class I. HLA class I expression were analyzed on lamivudine treated HepG2.2.15 by quantitative flow cytometry. Results Expression level of interferon gamma receptor 1 in the membrane was significantly higher in HepG2.2.15 cell line compared with HepG2 cell line and LO2 cell line (95.7% vs 55.5%,47.2%, P < 0.01). Similarly, the mRNA expression of receptors was drastically higher in HepG2.2.15 cell line than other two cell lines (0.92±0.12 vs 0.35 ±0.09 ,0.43±0.10, P <0.01). The initial level of the pSTAT1 was up regulated on HepG2 and HepG2.2.15 cells in the case of IFN γ stimulation. Moreover, there's no significant difference in time response required for nuclear translocation of phosphorylated STAT1 and dose response for the up regulation of MHC class I in HepG2.2.15 cell lines. Lamivudine treatment clearly increases the level of HLA class I on HepG2.2.15 under IFN γ stimuli. Conclusions Our results indicate that persistent existence of HBV replication can desensitize IFN gamma/STAT1 signaling in HepG2 cell line and down regulation of IFN gamma R2 chain surface expression.