慢性丙型肝炎病毒感染引起肝脏脂肪变的机制及脂肪肝诊断治疗的研究进展

丙型肝炎病毒(HCV)感染不仅引起急性和慢性病毒性肝炎,而且还与肝纤维化、肝细胞癌(HCC)的发生发展密切相关.除此之外,HCV的感染还引起肝脏脂肪变、冷球蛋白血症、B细胞淋巴瘤等,但是,这些病变形成的机制目前还不十分清楚.慢性丙型肝炎患者肝脏活检病理学特征,最明显的一点就是肝脏脂肪变,HCV慢性感染的黑猩猩肝脏病理学也有显著的脂肪变,HCV基因的转基因小鼠可引起明显的脂肪变,甚至HCV基因转染的细胞系也有脂滴的形成.所以,HCV感染引起肝脏脂肪变不是偶然的现象.在我们的肝炎病毒致病的分子生物学机制研究中,利用酵母双杂交技术,在国际上率先证实HCV核心蛋白可以与载脂蛋白AI(ApoAI)相结合,而且利用体外免疫共沉淀技术证实了这种结合作用,这一研究结果,促使我们重视HCV感染与慢性丙型病毒性肝炎与肝脏脂肪变的相关性.基于这一思路,我们对于159例慢性丙型肝炎患者肝组织脂肪变的临床与病理学特点、血清中各种脂蛋白、载脂蛋白等水平的改变进行了系统研究,除了在分子水平上证实了HCV感染引起肝脏脂肪变可能的分子生物学机制,而且利用HCV结构基因的转基因小鼠模型,对于HCV结构基因表达与肝脏脂肪变形成之间的相互关系进行了较为系统的观察.至此,在国内较早地系统研究了HCV感染引起的肝脏脂肪变的临床、病理学、血清生物化学、分子生物学和转基因小鼠的特点.虽然这些研究都还是初步的,有待于进一步加强,但是这些研究结果足以提示HCV感染肝脏脂肪变不是个别的现象,而是具有普遍的意义.特别是注意到HCV感染肝脏脂肪变与HCV感染者的肝脏纤维化及对抗病毒治疗的疗效应答有显著的影响,因此HCV感染肝脏脂肪变的研究也是探索HCV感染治疗新方法,乃至最终控制HCV感染,都有十分重要的意义.希望我们关于HCV感染与肝脏脂肪变的关系的研究,对于广大读者的慢性丙型肝炎的研究和临床工作有所裨益.     

HCV感染动物模型的研究进展

理想的HCV感染动物模型的建立,不仅有利于研究慢性丙型肝炎的致病机制(包括病毒-宿主相互作用、病毒变异性、宿主免疫应答规律),还为抗病毒药物的筛选和预防性疫苗的研发提供了更有效的技术途径。介绍了目前大家熟知的动物模型,包括黑猩猩模型、树鼩模型、小鼠模型等,并对各种模型的优势与缺陷进行了分析。近年来HCV感染小动物模型,尤其是转基因小鼠模型的建立,为HCV感染动物模型开创了新领域,是动物模型研究的热点和重点。     

胰岛素抵抗的HCV转基因鼠模型的建立

目的 建立胰岛素抵抗的丙型肝炎病毒(HCV)转基因鼠模型.方法 利用携带HCV Core稳定型表达载体,应用基因重组技术和显微注射技术,制备HCV转基因小鼠,用糖耐量试验和胰岛素耐量试验鉴定HCV转基因鼠出现胰岛素抵抗.结果 RT-PCR和Western blot结果表明成功构建了携带HCV Core转基因小鼠模型.1月龄转基因小鼠胰岛素水平明显高于正常鼠,胰岛素耐量试验异常,出现胰岛索抵抗.6月龄转基因小鼠出现肝脂肪变性.结论 成功制备胰岛素抵抗的HCV转基因鼠模型,为研究HCV核心蛋白所致胰岛素抵抗发病机制奠定了基础.     

调节性T细胞与持续性HCV感染

急性丙型肝炎患者容易转变为持续性HCV感染.近年来的研究表明,在慢性HCV感染中存在具有调节功能的T细胞亚群,它们在HCV感染的发病机制中起重要作用.此文就目前有关调节性T细胞的分化和功能,及其在持续性HCV感染中的意义和作用机制等研究进展作一综述.     

肝炎病毒感染与胰岛素抵抗

肝炎病毒慢性持续感染主要是由乙型肝炎病毒(HBV)和丙型肝炎病毒(HCV)所致, 除了引起肝脏损害外, 还与一些肝外组织的损害密切相关. 近年来, 研究资料显示慢性HCV和HBV感染与糖尿病和脂肪肝等代谢性疾病的发病密切相关, 而胰岛素抵抗(IR)可能是其发病机制的中心环节. IR也是肝纤维化进展的相关因素, 并影响慢性肝炎病毒感染时抗病毒治疗的疗效. 此外, 糖尿病还可能增加肝炎病毒致癌的作用, 应该引起肝病医师的高度重视. 本文就近年来对HCV和HBV感染中IR发生机制方面的研究, IR在HCV和HBV感染相关的糖尿病和脂肪肝中的作用和影响及其对临床的指导意义作一述评.     

丙型肝炎病毒细胞模型和动物模型的研究

建立丙型肝炎病毒(HCV)的细胞模型及动物模型,对于深入认识HCV病原学特点、复制及发病机制,筛选有效药物及疫苗等极为重要。近年来,国内外学者作了大量探讨,概括如下。 1 HCV细胞模型的研究 1.1 HCV感染类细胞模型 1.1.1 以肝细胞为宿主的HCV感染细胞模型 众所周知,人肝细胞是HCV感染的天然宿主细胞,以成人肝细胞作为感染HCV的细胞模型应有更好的代表性。Ito等直接将HCV阳性血清与丙肝患者肝活检分离出来的肝细胞共培养,发现肝细胞内和培养上清液中可检出大量HCV RNA,用     

丙型肝炎病毒受体研究现状及展望

在HCV感染宿主过程中，病毒首先结合到靶细胞表面，经受体介导进入细胞，然后才能复制、表达病毒蛋白并引起相关的病理变化。因此，HCV宿主细胞表面的受体或辅助受体的研究显得尤为重要。目前难以从感染的血清和组织中分离天然HCV病毒颗粒，此外缺乏有效的体外病毒复制系统和小动物模型，所以，HCV宿主细胞表面受体及HCV感染靶细胞机制仍不太清楚。     

具有cre/loxP转换系统的HCV转基因鼠伴有凋亡性细胞死亡的肝损伤

HCV持续感染的分子机制和肝损伤的发病机制仍不清楚。缺乏适宜的培养系统和动物模型阻碍了目前研究。为建立HCV感染动物模型,我们获得cre/loxP转换表达系统控制下的HCV cDNA 转基因(Tg)鼠。方法:为组建HCV转基因鼠表达单元,将loxP填充序列插入GAG启动子和HCV cNA、CN2(核心ns2)间。构建一种重组非竞争复制腺病毒-Ax-     

载脂蛋白B基因启动子多态性与慢性丙型肝炎病毒感染的关系

丙型病毒性肝炎越来越受到重视，但HCV进入宿主肝细胞的机制尚不明。近年来，不少学者已证实HCV感染与脂代谢相关，低密度脂蛋白受体（LDLR）为HCV受体，HCV与人血清中β脂蛋白结合，通过LDLR感染肝细胞是HCV感染的重要机制之一。     

丙型肝炎病毒感染实验模型的研究新进展

丙型肝炎病毒(HCV)感染是继乙型肝炎病毒之后引起慢性肝炎、肝硬化以及肝细胞癌的又一主要病因.HCV易感宿主选择有限,至今尚不能建立稳定、易行的HCV感染细胞及动物模型系统,使得病毒变异性、复制机制、与宿主蛋白相互作用以及新药与疫苗研发等相关研究受到极大限制.本文就近年来围绕持续稳定的HCV体外细胞或动物感染模型的研究新进展作一综述.     

HCV实验动物模型研究进展

HCV是威胁人类健康的重要病原体之一,可在人体肝脏形成持续性感染,导致慢性肝炎、肝纤维化、肝硬化和肝癌。HCV的实验动物模型不仅是HCV免疫学、病理学和病毒学等基础科学的重要研究手段,还为HCV疫苗和药物的研发提供了关键的工具和平台。黑猩猩是除了人类以外唯一可以被HCV感染的灵长类动物,为HCV的研究做出了重要贡献,但其使用受到了成本及伦理上的限制。近年在利用树鼩和人源化小鼠建立HCV小动物模型的研究上取得良好的进展。本文将总结常用HCV实验动物模型的现状和挑战。     

New animal models for hepatitis C viral infection and pathogenesis studies

Hepatitis C virus (HCV) is a major cause of chronic live disease, cirrhosis and hepatocellular carcinoma (HCC) In man, the pathobiological changes associated wit HCV infection have been attributed to both the immun system and direct viral cytopathic effects. Until now, th lack of simple culture systems to infect and propagat the virus has hampered progress in understandin the viral life cycle and pathogenesis of HCV infection including the molecular mechanisms implicated in HCV induced HCC. This clearly demonstrates the need t develop small animal models for the study of HCV associated pathogenesis. This review describes an discusses the development of new HCV animal models t study viral infection and investigate the direct effects o viral protein expression on liver disease.     

Animal models for hepatitis C and related liver disease

Persistent infection with hepatitis C virus (HCV) is a major risk toward development of hepatocellular carcinoma (HCC). The elucidation of pathogenesis of HCV-associated liver disease is hampered by the absence of appropriate animal models: there has been no animal model for HCV infection/pathogenesis except for the chimpanzee. In contrast, a number of transgenic mouse lines carrying the cDNA of the HCV genome have been established and evaluated in the study of HCV pathogenesis. The studies using transgenic mouse models, in which the HCV proteins such as the core protein are expressed, indicate the direct pathogenicity of HCV, including oncogenic activities. HCV transgenic mouse models also show a close relationship between HCV and some hepatic and extrahepatic manifestations such as hepatic steatosis, insulin resistance or Sjögren's syndrome. A crucial role of hepatic steatosis and insulin resistance in the pathogenesis of liver disease in HCV infection has been demonstrated, implying hepatitis C to be a metabolic disease. Besides the data connecting liver fibrosis progression and the disturbance in lipid and glucose metabolisms in hepatitis C patients, a series of evidence was found showing the association between these two conditions and HCV infection, chiefly using transgenic mouse carrying the HCV genome. Furthermore, the persistent activation of peroxisome proliferator-activated receptor (PPAR)-α has recently been found, yielding dramatic changes in the lipid metabolism and oxidative stress overproduction in cooperation with the mitochondrial dysfunction. These results would provide a clue for further understanding of the role of lipid metabolism in pathogenesis of hepatitis C including liver injury and hepatocarcinogenesis.     

Effects of HCV proteins in current HCV transgenic models

Hepatits C virus (HCV) is an enveloped virus with positive‐sense single‐stranded RNA genome that causes both acute and persistent infections associated with chronic hepatitis, cirrhosis and hepatocellular carcinoma, which needs fully functional human hepatocytes for its development. Due to the strict human tropism of HCV, only human and higher primates such as chimpanzees have been receptive to HCV infection and development, cognition about pathophysiololgy and host immune responses of HCV infection is limited by lacking of simple laboratory models of infection for a long time. During the past decade, gene transfer approaches have been helpful to the understanding of the molecular basis of human disease. Transgenic cell lines, chimeric and transgenic animal models were developed and had been demonstrated their invaluable benefits. This review focuses on the existing HCV transgenic models and summarize the relative results about probable pathophysical changes induced by HCV proteins.     

Molecular mechanisms of hepatocarcinogenesis in chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection is a major cause of hepatocellular carcinoma (HCC) and chronic liver disease worldwide. Recent developments and advances in HCV replication systems in vitro and in vivo, transgenic animal models, and gene expression profiling approaches have provided novel insights into the mechanisms of HCV replication. They have also helped elucidate host cellular responses, including activated/inactivated signaling pathways, and the relationship between innate immune responses by HCV infection and host genetic traits. However, the mechanisms of hepatocyte malignant transformation induced by HCV infection are still largely unclear, most likely due to the heterogeneity of molecular paths leading to HCC development in each individual. In this review, we summarize recent advances in knowledge about the mechanisms of hepatocarcinogenesis induced by HCV infection.     

Mouse models for the study of HCV infection and virus-host interactions

Hepatitis C virus (HCV) is a major cause of chronic liver disease including steatosis, cirrhosis and hepatocellular carcinoma. The development of transgenic mice expressing HCV proteins and the successful repopulation of SCID/Alb-uPA mice with human hepatocytes provides an important tool for unraveling virus-host interactions in vivo. Several of these mouse models exhibit aspects of HCV-related liver disease. Thus, these in vivo models play an important role to further understand the pathogenesis of HCV infection and to evaluate the pre-clinical safety and efficacy of new antiviral compounds against HCV. This review summarizes the most important mouse models currently used to study HCV pathogenesis and infection. Finally, the perspective of these models for future HCV research as well as the design of novel small animal models is discussed.     

Hepatitis C virus: Morphogenesis,infection and therapy

Hepatitis C virus(HCV) is a major cause of liver diseases including liver cirrhosis and hepatocellular carcinoma. Approximately 3% of the world population is infected with HCV. Thus, HCV infection is considered a public healthy challenge. It is worth mentioning, that the HCV prevalence is dependent on the countries with infection rates around 20% in high endemic countries. The review summarizes recent data on HCV molecular biology, the physiopathology of infection(immune-mediated liver damage, liver fibrosis and lipid metabolism), virus diagnostic and treatment. In addition, currently available in vitro, ex vivo and animal models to study the virus life cycle, virus pathogenesis and therapy are described. Understanding of both host and viral factors may in the future lead to creation of new approaches in generation of an efficient therapeutic vaccine.     

Animal models for the study of hepatitis C virus infection and replication

Hepatitis C virus (HCV) hepatitis, initially termed non-A, non-B hepatitis, has become one of the leading causes of cirrhosis and hepatocellular carcinoma worldwide. With the help of animal models, our understanding of the virus has grown substantially from the time of initial discovery. There is a paucity of available animal models for the study of HCV, mainly because of the selective susceptibility limited to humans and primates. Recent work has focused modification of animals to permit HCV entry, replication and transmission. In this review, we highlight the currently available models for the study of HCV including chimpanzees, tupaia, mouse and rat models. Discussion will include methods of model design as well as the advantages and disadvantages of each model. Particular focus is dedicated to knowledge of pathophysiologic mechanisms of HCV infection that have been elucidated through animal studies. Research within animal models is critically important to establish a complete understanding of HCV infection, which will ultimately form the basis for future treatments and prevention of disease.     

Current status of a hepatitis C vaccine: Encouraging results but significant challenges ahead

Persistent hepatitis C virus (HCV) infection affects 170 million people worldwide. Acute HCV infection is often asymptomatic, but many infected individuals develop persistent infections that may lead to development of end-stage liver diseases, including liver cirrhosis and hepatocellular carcinoma. Thus, an HCV vaccine that could significantly lower the chronicity rate would have a major impact on the disease burden. Unfortunately, HCV is a highly mutable virus, and escape mutations can undermine vaccine-induced virus-specific immunity. Also, HCV exists as multiple genotypes, and so genotype-specific vaccines might be required to achieve broad protection. Finally, vaccine development has been hampered by the lack of a small animal model and cell culture systems, but these are currently being established. Despite these obstacles, several vaccine candidates tested in the chimpanzee HCV model have shown some encouraging results.     

Validation of connective tissue growth factor (CTGF/CCN2) and its gene polymorphisms as noninvasive biomarkers for the assessment of liver fibrosis

Summary.  Clinical and experimental studies have demonstrated that connective-tissue growth factor (CTGF) expression is increased in fibrotic human liver and experimental animal models of liver fibrogenesis. CTGF has been linked to transforming growth factor-beta (TGF-β) pathways in fibroproliferative diseases and specific polymorphisms within the CTGF gene may predispose for fibrosis in systemic sclerosis. As CTGF is detectable in various human fluids (serum, plasma and urine), it may provide information about fibrotic remodelling processes and reflect hepatic TGF-β bioactivity. We established a novel ELISA for the measurement of serum CTGF and tested its clinical value in patients with chronic hepatitis C virus (HCV) infection and chronic liver disease (CLD). HCV infected patients ( n  =   138) had significantly higher serum CTGF levels than healthy controls. CTGF was linked to the histological degree of liver fibrosis. To expand the results to other aetiologies, a separate cohort of CLD patients ( n  =   129) was evaluated, showing higher serum CTGF than healthy controls and again an association with advanced stages of liver cirrhosis (Child B and C). Although independent of the underlying aetiology, serum CTGF was most powerful in indicating fibrosis/advanced disease states in HCV-related disorders. The genotyping of six polymorphisms (rs6917644, rs9399005, rs6918698, rs9493150, rs2151532 and rs11966728) covering the CTGF locus in 365 patients suffering from chronic hepatitis C revealed that none of these polymorphisms showed a genotypic or allelic association with the severity of hepatic fibrosis. Taken together, serum CTGF is suitable for determination of hepatic fibrosis and most powerful in patients with chronic HCV infection.