Pathogenic Mechanisms of Virus Induced Biliary Atresia

描述(由申请人提供)： 胆道闭锁是新生儿胆汁淤积的最常见原因，如果不进行治疗，会导致终末期肝病(ESLD)和死亡。即使在目前的治疗策略下，大多数儿童仍会发展为进展性肝病，需要肝移植来挽救。胆道闭锁是小儿肝移植的首要适应症。尽管胆道闭锁很重要，但其发病机制尚不清楚。一个可能的原因是环境因素的感染，如易感宿主中的病毒。我们建立了一种实验性的胆道闭锁小鼠模型，发现一种特殊的轮状病毒种-恒河猴轮状病毒(RRV)可以在易感小鼠宿主BALB/c小鼠中诱导胆道损伤，并进展为ESLD和死亡。炎症性胆管病始于胆管上皮细胞水平，反映了婴儿的疾病过程。这个模型将被用来定义调节病毒和胆道系统之间相互作用的分子机制，检验胆道闭锁是由于病毒对胆管上皮细胞(胆管细胞)的异常识别和感染而导致的最重要的假说。这一假设将通过以下具体目的来解决：1)确定诱导小鼠胆道闭锁所必需的特异性RRV基因(S)。2)确定胆囊虫对RRV感染的易感机制。3)确定RRV感染的胆管细胞触发宿主炎症反应的机制。轮状病毒的基因重排特性将被用于鉴定引起胆道闭锁小鼠模型的轮状病毒基因(S)。一种新的RRV能够感染胆管细胞系的体外模型将被用来确定RRV感染胆管细胞的机制。用流式细胞术检测整合素apha2beta1的存在，已知的整合素apha2beta1是轮状病毒感染的易感性。将使用天然配体和针对该蛋白的单抗进行阻断研究，以确定其作用。在体外，RRV感染的胆管细胞产生趋化因子。这可能是启动宿主炎症反应的触发机制。我们将确定在体内是否发生了类似的过程。我们还将确定核因子-kappaB细胞内途径是否是RRV感染诱导趋化因子产生的机制。

DESCRIPTION (provided by applicant): Biliary atresia is the most common cause of neonatal cholestasis and if untreated results in end-stage liver disease (ESLD) and death. Even with current treatment strategies most children develop progressive liver disease and require liver transplantation for salvage. Biliary atresia is the number one indication for pediatric liver transplantation. Despite its importance, the pathogenesis of biliary atresia is unknown. One possible cause is an infection by an environmental agents such as viruses in a susceptible host. We established an experimental mouse model of biliary atresia and found that biliary injury in mice could be induced by a specific rotavirus species - rhesus rotavirus (RRV) in a susceptible murine host - BALB/c mice that progresses to ESLD and death. The inflammatory cholangiopathy is initiated at the biliary epithelial cell level and mirrors the disease process that is found in infants. This model will be used to define the molecular mechanisms regulating the interaction between a virus and the biliary system testing the over-arching hypothesis that the biliary atresia results from the abnormal recognition and infection of biliary epithelial cells (cholangiocytes) by a virus. This hypothesis will be addressed by the following specific aims: 1) Determine the specific RRV gene(s) necessary for the induction of biliary atresia in mice. 2) Determine the mechanism by which the cholangicoyte is susceptible to RRV infection. 3) Determine the mechanism by which RRV infected cholangiocytes triggers a host inflammatory response. The rotavirus property of gene reassortment will be used to identify the RRV gene(s) that cause the murine model of biliary atresia. A novel in vitro model in which RRV is able to infect a cholangiocyte cell line will be used to identify the mechanism by which RRV infects the cholangicoyte. Flow cytometry was used to detect the presence of the integrin apha2beta1 known to confer vulnerabiity to rotavirus infection. Blocking studies using natural ligands and monoclonal antibodies against this protein will be performed to determine its role. In vitro, cholangiocytes infected by RRV produce chemokines. This may be the triggering mechanism by which the host inflammatory response is initiated. We will determine if a similar process occurs in vivo. We will also determine if the NF-kappaB intracellular pathway is the mechansim by which RRV infection induces chemokine production.