dnTGF Beta RII Mice and PBC

描述（由申请人提供）：原发性胆汁性肝硬化（PBC）是一种胆汁特异性自身免疫性疾病，其特征为门脉淋巴细胞浸润、抗线粒体抗体（AMA）和选择性胆管上皮破坏。虽然PBC通常被认为是一种自身免疫性疾病的模型，并且在定义PBC患者中的晚期自身免疫效应物（自身抗体、T细胞和B/T自身表位）方面已经有了显著的进展，但这些数据尚未转化为新的疗法。在人类PBC中存在延长的无症状临床前阶段，因此，导致胆道损伤的最早事件在很大程度上是未知的。发病和临床症状之间的这种差距阻碍了理解导致自我耐受性破坏的事件的努力。我们的实验室将利用一种独特的PBC小鼠模型，即在CD 4启动子（dnTGF-β RII）控制下表达显性阴性TGF-β受体II基因的小鼠。这些小鼠发展出强烈的炎症性胆道疾病和100%的AMA转移率。我们在当前资助期间取得的进展导致了重要的，新颖的，在某些情况下令人惊讶的结果，使我们能够解决三个关键领域，这些领域有可能定义导致耐受性破坏，胆管炎和肝纤维化的免疫病理学。首先，CD 8 T细胞介导胆道病理学，更重要的是，KLRG 1+效应CD 8 T细胞亚群在肝脏中积累，但仅在存在缺陷性dnTGF-β RII T细胞的情况下。我们的目标将是确定KLRG 1+表型，其转移疾病的能力，以及Treg介导的控制这一关键细胞亚群的机制。其次，我们已经证明dnTGF-β RII小鼠中IL-12 p35的缺失不仅会导致门静脉炎症和胆管损伤，还会导致不同细胞因子的纤维化 profile.我们将利用这一观察结果并连续监测这些事件，以确定在功能失调的TGF-β信号传导过程中病理性细胞因子的来源，以及通过利用缺乏IL-17 A，IL-17 F，IL-22，IL-23 p19或IL-17 RA，以及独特的骨髓嵌合小鼠模型。最后，我们发表的数据表明，microRNA失调在自身反应性CD 8 T细胞介导的胆道病理学中起着重要作用。我们现有的模型和新提出的方法将使我们能够纠正这种失调，并测试纠正的miRNA生物合成对T细胞活化状态的影响，更重要的是，对免疫病理学的影响。我们认为，该提案的结果将提供对CD 8效应子介导的损伤的作用机制的深入了解，将提供开发最早免疫介导的纤维化事件的生物网络的机会，并最终提供关于微小RNA在自身免疫性胆管炎中的作用的关键机制信息。重要的是，我们相信这些数据将有可能确定治疗靶向的新途径。

DESCRIPTION (provided by applicant): Primary biliary cirrhosis (PBC) is a biliary specific autoimmune disease characterized by lymphocytic infiltrates of portal tracts, anti-mitochondrial antibodies (AMAs) and selected destruction of the biliary epithelium. Although PBC is often considered a model autoimmune disease and there have been significant advances in defining the late stage autoimmune effectors (autoantibodies, T cells, and B/T autoepitopes) in PBC patients, such data has not been translated to new therapies. There is an extended silent preclinical phase in human PBC and, as such, the earliest events that lead to biliary damage are largely unknown. This gap between onset and clinical symptoms has frustrated efforts to understand the events that lead to breach of self-tolerance. Our laboratories will take advantage of a unique murine model of PBC, mice that express a dominant-negative TGF-ß receptor II gene under control of the promoter for CD4 (dnTGF-ßRII). These mice develop a robust inflammatory biliary disease and 100% penetrance of AMAs. Our progress during the current period of funding has led to important, novel and in some cases surprising results that allow us to address three critical areas that have the potential to define the immunopathology leading to breach of tolerance, cholangitis and hepatic fibrosis. First, CD8 T cells mediate biliary pathology and, more importantly, the KLRG1+ effector CD8 T cell subset accumulates in the liver, but only in the presence of defective dnTGF-ßRII Tregs. Our goal will be to define the KLRG1+ phenotype, its ability to transfer disease, and the mechanism of Treg-mediated control of this critical cell subset. Second, we have shown that deletion of IL-12p35 in dnTGF-ßRII mice leads not only to portal inflammation and bile duct damage, but also to fibrosis with a distinct cytokine profile. We will take advantage of this observation and serially monitor these events to define the sources of pathologic cytokines in the course of dysfunctional TGF-ß signaling as well as define how IL-17 signaling is cross-regulated by cytokines in the course of a chronic immune response by taking advantage of transgenic dnTGF-ßRII mice that lack IL-17A, IL-17F, IL-22, IL- 23p19 or IL-17RA in addition to unique bone marrow chimeric mouse models. Finally, our published data show that microRNA dysregulation plays a major role in autoreactive CD8 T cell mediated biliary pathology. Our existing models and novel proposed methods will allow us to correct this dysregulation and to test the effect of corrected miRNA biosynthesis on T cell activation status, and, more importantly, on immunopathology. We submit that the results of this proposal will provide insight into the mechanisms of action of CD8 effector mediated damage, will provide the opportunity to develop a biologic network of the earliest immune mediated fibrotic events and finally critical mechanistic information on the role of micro- RNA in autoimmune cholangitis. Importantly, we believe these data will potentially identify new pathways for therapeutic targeting.