T Cell-Mediated Mechanisms of Autoimmunity in Murine and Human Biliary Atresia

描述（由申请人提供）：项目摘要。胆道闭锁（BA）是一种进行性、炎性、硬化性肝外和肝内胆管病变，发生于婴儿期，可导致胆管梗阻和胆汁性肝硬化。大多数患者的肝内胆管炎症和硬化进展导致80%的患者需要肝移植，占所有儿科肝移植的一半。目前对BA的治疗是不充分的，因为BA的病因和发病机制尚不清楚，但是围产期感染和自身免疫介导的胆管损伤的作用已被提出参与。在这个提议中要检验的假设是BA是一种病毒诱导的胆道系统自身免疫性疾病，其中T细胞介导的自身免疫反应靶向胆管上皮。由于BA的稀有性和对人体组织的有限可及性，在这些研究中将使用恒河猴轮状病毒（RRV）诱导的BA小鼠模型。我们将研究已知感染触发自身免疫性疾病的两种不同机制：分子模拟和旁观者激活。本申请的初步数据表明，自身反应性胆管上皮特异性T细胞浸润RRV诱导的BA小鼠的肝脏，并且这些T细胞过继转移到naTve SCID受体中导致胆管靶向炎症。还将使用人BA组织进行补充研究。在人BA中，导管周围炎症由Th1细胞和巨噬细胞组成。我们最近已经确定，T细胞是寡克隆的性质，这表明特异性抗原驱动的T细胞活化。因此，本提案的具体目的是详细研究T细胞介导的自身免疫机制在小鼠和人BA胆管损伤中的作用。具体目的I是确定从BA小鼠产生的肝T细胞杂交瘤的抗原特异性。杂交技术是一种用于研究T细胞受体对抗原识别的精细特异性的有力工具。具体目的II是通过从胆管上皮cDNA表达文库中分子克隆来鉴定作为T细胞活化的靶点的胆管上皮肽。在特定目标III中，我们将分析来自人BA肝脏和肝外胆管残留物的T细胞，并确定负责T细胞活化和增殖的刺激蛋白（病毒或胆管上皮细胞）。本案无关该建议的意义在于仔细定义BA在小鼠模型中的免疫发病机制，然后将其转化为BA婴儿组织中的研究。在BA的小鼠模型中描绘自身免疫介导的损伤的途径应该刺激针对人类的新的医学干预措施的开发，旨在抑制免疫应答和减少胆管损伤。这项研究计划的总体目标是利用这些分子和免疫学的见解作为基础，为这一重要疾病的未来治疗和预防策略的发展。

DESCRIPTION (provided by applicant): Project Summary. Biliary atresia (BA) is a progressive, inflammatory, sclerosing extrahepatic and intrahepatic cholangiopathy which presents in infancy and leads to bile duct obstruction and biliary cirrhosis. Intrahepatic biliary inflammation and sclerosis progresses in most patients with the resulting need for liver transplantation in 80% of patients, accounting for half of all pediatric liver transplants. Current therapy for BA is inadequate because the etiology and pathogenesis of BA is not understood, however the role of perinatal infection and autoimmune-mediated bile duct injury have been proposed to be involved. The hypothesis to be tested in this proposal is that BA is a viral-induced autoimmune disease of the biliary system, in which T cell-mediated autoimmune responses target bile duct epithelia. Due to the rarity of BA and the limited accessibility to human tissue, the Rhesus rotavirus (RRV)-induced murine model of BA will be utilized in these investigations. We will examine two distinct mechanisms by which infections are known to trigger autoimmune disease: molecular mimicry and bystander activation. Preliminary data for this application demonstrate that autoreactive bile duct epithelial-specific T cells infiltrate the livers of RRV-induced BA mice, and that adoptive transfer of these T cells into naTve SCID recipients leads to bile duct targeted inflammation. Complementary studies will also be performed with human BA tissue. In human BA, the periductal inflammation is composed of Th1 cells and macrophages. We have recently determined that the T cells are oligoclonal in nature, suggesting specific antigen-driven T cell activation. Thus, the specific aims of this proposal are to investigate in detail the role of T cell-mediated autoimmune mechanisms in bile duct injury in both murine and human BA. Specific Aim I is to determine the antigen specificity of liver T cell hybridomas generated from BA mice. Hybridoma technology is a powerful tool used to study the fine specificity of antigen recognition by the T cell receptor. Specific Aim II is to identify the bile duct epithelial peptide that is the target of T cell activation by molecular cloning from a bile duct epithelial cDNA expression library. In Specific Aim III we will analyze the T cells from human BA livers and extrahepatic bile duct remnants and determine the stimulating protein (virus or bile duct epithelia) responsible for the T cell activation and proliferation. Relevance. The significance of this proposal lies in carefully defining the immunopathogenesis of BA in the murine model which will then be translated into investigations in tissues from infants with BA. Delineating the pathways of autoimmune mediated injury in the murine model of BA should stimulate development of novel medical interventions for humans aimed at suppressing the immune response and decreasing bile duct injury. The overall goal of this research program is to use these molecular and immunological insights as a basis for development of future therapeutic and preventative strategies for this important disease.