干扰素抗病毒蛋白MxA和2',5'-OAS在肝胚瘤细胞株中的差异表达

目的了解α干扰素(interferon-α,IFN-α)诱导的抗病毒蛋白MxA和2',5'-寡腺苷酸合成酶(2',5'-OAS)在人肝胚瘤细胞株HepG2和HBV稳定转染的HepG2.2.15细胞中的表达情况。方法将培养的HepG2和HepG2.2.15细胞用IFN-α刺激6h,分离细胞总RNA,经逆转录、32P标记后与尼龙膜上的探针微矩阵(macroarray法)进行分子杂交;并以此来分析HepG2和HepG2.2.15细胞IFN抗病毒基因表达谱。用免疫印迹分析IFN抗病毒蛋白;如,MxA、2',5'-OAS等在肝胚瘤细胞中的表达。结果分析发现在HepG2和HepG2.2.15细胞仅有部分IFN诱导基因表达,多数IFN诱导基因呈低表达或不表达。比较HepG2和HepG2.2.15细胞,发现两者表达IFN诱导基因有差异,即对IFN应答有差异。研究中发现,MxA蛋白在HepG2.2.15细胞中不表达,而在HepG2细胞中却能正常表达。另一种重要的IFN抗病毒蛋白2',5'-OAS,在HepG2.2.15和HepG2细胞中均能表达;在拉米夫啶处理下,HepG2.2.15细胞甚至比HepG2细胞能更好地表达。结论IFN抗病毒蛋白MxA和2',5'-OAS在人肝胚瘤细胞株HepG2和HBV稳定转染的HepG2.2.15细胞中表现出差异的表达模式;HBV及其抗原成分影响人肝胚瘤细胞株的IFN抗病毒基因表达。

Immunostaining of PD-1/PD-Ls in liver tissues of patients with hepatitis and hepatocellular carcinoma

AIM: To investigate the expression of programmed death (PD)-1,PD ligand 1 (PD-L1) and PD-L2 in liver tissues in the context of chronic hepatitis and hepatocellular carcinoma (HCC).METHODS: Liver biopsies and HCC specimens from patients were collected and histologically examined.The expression of PD-1,PD-L1,and PD-L2 in biopsy specimens of chronic hepatitis and HCC specimens was evaluated by immunohistochemical staining.The association between the expression level of PD-1,PD-L1,and PD-L2 and clinical and pathological variables was analyzed statistically.RESULTS: Expression of PD-1 was found in liverinfiltrating lymphocytes.In contrast,PD-L1 and PD-L2 were expressed in non-parenchyma liver cells and tumor cells.The expression of PD-L1 was significantly correlated with hepatitis B virus infection (1.42 ± 1.165 vs 0.50 ± 0.756,P = 0.047) and with the stage of HCC (7.50 ± 2.121 vs 1.75 ± 1.500 vs 3.00 ± 0.001,P = 0.018).PD-1 and PD-Ls were significantly up-regulated in HCC specimens (1.40 ± 1.536 vs 5.71 ± 4.051,P = 0.000;1.05 ± 1.099 vs 4.29 ± 3.885,P = 0.004;1.80 ± 1.473 vs 3.81 ± 3.400,P = 0.020).CONCLUSION: PD-L1 may contribute to negative regulation of the immune response in chronic hepatitis B.PD-1 and PD-Ls may play a role in immune evasion of tumors.

Interferon-α response in chronic hepatitis B-transfected HepG2.2.15 cells is partially restored by lamivudine treatment

AIM: To characterize the IFN-response and its modul- ation by the antiviral compound lamivudine in HBV- transfected HepG2.2.15 cells. METHODS: HepG2.2.15 and HepG2 cells were stimulated with various concentrations of IFN-a2a in the presence or absence of lamivudine. Then, total RNA was extracted and analysed by customised cDNA arrays and northern blot for interferon-inducible genes (ISGs). In addition, cellular proteins were extracted for EMSA and western blot. HBV replication was assessed by southern blot or ELISAs for HBsAg and HBeAg. RESULTS: Two genes (MxA, Cig5) with completely abolished and 4 genes (IFITM1, -2, -3, and 6-16) with partially reduced IFN-responses were identified in HepG2.2.15 cells. In 2 genes (IFITM1, 6-16), the response to IFN-a could be restored by treatment with lamivudine. This effect could not be explained by a direct modulation of the Jak/Stat signalling pathway since EMSA and western blot experiments revealed no suppression of Stat1 activation and ISGF3 formation after stimulation with IFN-a in HepG2.2.15 compared to HepG2 cells. CONCLUSION: These results are consistent with the assumption that chronic hepatitis B may specifically modulate the cellular response to IFN by a selective blockage of some ISGs. Antiviral treatment with lamivudine may partially restore ISG expression by reducing HBV gene expression and replication.

New therapeutic vaccination strategies for the treatment of chronic hepatitis B

Chronic hepatitis B virus(CHB) is currently treated with either interferon-based or nucleot(s)idebased antiviral therapies.However,treatment with pegylated interferon alpha results in a durable antiviral response in only about 30%patients and is associated with side effects.Most patients receiving nucleot(s)ide analogue treatment do not establish long-term,durable control of Infection and have rebounding viremia after cessation of therapy.Thus,novel therapy strategies are necessary to achieve the induction of potent and durable antiviral immune responses of the patients which can maintain long-term control of viral replication.Therapeutic vaccination of HBV carriers is a promising strategy for the control of hepatitis B.Here the authors review new therapeutic vaccination strategies to treat chronic hepatitis B which may be introduced for patient treatment in the future.

Sequence diversity of hepatitis C virus: Implications for immune control and therapy

With approximately 3% of the world’s population (170 million people) infected with the hepatitis C virus (HCV), the WHO has declared HCV a global health problem. Upon acute infection about 50%-80% of subjects develop chronic hepatitis with viral persistence being at risk to develop liver cirrhosis and hepatocellular carcinoma. One characteristic of HCV is its enormous sequence diversity, which represents a significant hurdle to the development of both effective vaccines as well as to novel therapeutic interventions. Due to a polymerase that lacks a proofreading function HCV presents with a high rate of evolution, which enables rapid adaptation to a new environment including an activated immune system upon acute infection. Similarly, novel drugs designed to specifically inhibit viral proteins will face the potential problem of rapid selection of drug resistance mutations. This review focuses on the sequence diversity of HCV, the driving forces of evolution and the impact on immune control and treatment response. An important feature of any therapeutic or prophylactic intervention will be an efficient attack of a structurally or functionally important region in the viral protein. The understanding of the driving forces, but also the limits of viral evolution, will be fundamental for the design of novel therapies.

Regulation of Hepatitis C Virus Replication and Gene Expression by the MAPK-ERK Pathway

The mitogen activated protein kinases-extracellular signal regulated kinases (MAPK-ERK) pathway is involved in regulation of multiple cellular processes including the cell cycle. In the present study using a Huh7 cell line Con1 with an HCV replicon, we have shown that the MAPK-ERK pathway plays a significant role in the modulation of HCV replication and protein expression and might influence IFN-α signalling. Epithelial growth factor (EGF) was able to stimulate ERK activation and decreased HCV RNA load while a MAPK-ERK pathway inhibitor U0126 led to an elevated HCV RNA load and higher NS5A protein amounts in Con1 cells. It could be further demonstrated that the inhibition of the MAPK-ERK pathway facilitated the translation directed by the HCV internal ribosome entry site. Consistently, a U0126 treatment enhanced activity of the HCV reporter replicon in transient transfection assays. Thus, the MAPK-ERK pathway plays an important role in the regulation of HCV gene expression and replication. In addition, cyclin-dependent kinases (CDKs) downstream of ERK may also be involved in the modulation of HCV replication since roscovitine, an inhibitor of CDKs had a similar effect to that of U0126. Modulation of the cell cycle progression by cell cycle inhibitor or RNAi resulted consistently in changes of HCV RNA levels. Further, the replication of HCV replicon in Con1 cells was inhibited by IFN-α. The inhibitory effect of IFN-α could be partly reversed by pre-incubation of Con-1 cells with inhibitors of the MAPK-ERK pathway and CDKs. It could be shown that the MAPK-ERK inhibitors are able to partially modulate the expression of interferon-stimulated genes.

Recent Advances in Research on Hepadnaviral Infection in the Woodchuck Model

The woodchuck model is an excellent animal model to study hepadnaviral infection. The new progresses in this model made possible to examine the T-cell mediated immune responses in acute and chronic hepadnaviral infection. Recently, a new assay for cytotoxic T-cells based on detection of CD107 was established for the woodchuck model. In addition, new immunotherapeutic approaches based on combination of potent antiviral treatment and DNA-protein vaccines were proven to be useful for treatment of chronic hepatitis B.

FOREWORD

Chronic viral hepatitis continues to be a major public health problem and the most common cause of liver disease worldwide. It is estimated that 350 million people are carriers of hepatitis B virus (HBV) and 170 million are

新型低密度cDNA Macroarray的建立及其应用于干扰素抗HBV的研究

目的了解人肝胚瘤细胞株HepG2和稳定转染HBV全基因组细胞株HepG2.2.15的干扰素(IFN)抗病毒基因表达谱。方法选择与IFN抗病毒及其信号转导途径相关的288个IMAGE克隆,经聚合酶链反应(PCR)扩增相应的基因片段,将扩增的DNA片段纯化后点样于阳离子尼龙膜上以制备成人工芯片。HepG2和HepG2.2.15细胞经IFN处理后,分离细胞总RNA,进行逆转录并且同时以32P标记;将标记的cDNA靶基因与尼龙膜上的探针进行分子杂交。经Cyclone扫描系统和OptiQuantTM软件处理,将图像信号转换成数据信息;再经Excel软件分析、处理形成Macroarray数据值。结果Macroarray分析提示,在HepG2和HepG2.2.15细胞仅有部分IFN诱导基因表达,多数IFN诱导基因呈低表达或不表达。通过比较HepG2和HepG2.2.15细胞,发现两者表达IFN诱导基因有差异,即对IFN应答有差异。进一步分析还发现,尽管与HepG2细胞存在差异的IFN应答,HepG2.2.15细胞的IFN信号转导途径(JakSTAT途径)却是开放的、未受损伤的。结论HepG2和HepG2.2.15细胞具有差异的IFN抗病毒基因表达谱。

土拨鼠肝炎病毒核心蛋白的高效表达和B细胞表位鉴定

目的建立高效表达土拨鼠肝炎病毒核心蛋白(WHcAg)的方法并对其B细胞表位进行鉴定。方法分别构建不同截短型WHcAg的质粒以了解能大量表达并形成WHV核心颗粒的区段,利用变性WHcAg制备单克隆抗体以寻找能与WHcAg线性B细胞表位结合的单克隆抗体。结果WHcAg前144或149氨基酸残基能够大量表达并能形成颗粒样结构。这2种截短型WHcAg能够在大肠杆菌中表达并组装成直径为34 nm的核心颗粒,最终纯化获得毫克级的核心蛋白。截短型WHcAg保留了全长WHcAg的抗原性,而且变性WHcAg存在另外的B细胞线性表位,利用变性WHcAg进行免疫制备单克隆抗体获得的5株抗体均针对WHcAg的N末端表位,该表位在WHcAg和HBcAg高度保守。结论建立了高效表达WHcAg的方法,制备了针对WHcAg单克隆抗体。并对WHcAg的线性B细胞表位进行了鉴定,发现WHcAg和HBcAg的N末端存在共同的线性B细胞表位。