dnTGF Beta RII Mice and PBC

描述（由申请人提供）：原发性胆汁性肝硬化（PBC）是一种肝脏特异性自身免疫性疾病，其特征是门道淋巴细胞浸润、胆道上皮细胞选择性破坏和抗线粒体抗体（AMAs）的存在。PBC的研究进展一直受到其发病隐秘性和进入人体肝脏的局限性的阻碍。我们利用转基因小鼠的优势，在CD4启动子的指导下直接表达显性阴性形式的转化生长因子(TGF)-2受体II型（dnTGF2RII），并证明这些小鼠具有PBC的几个关键特征，包括自发产生针对PDC-E2， BCOADC-E2和OGDC-E2的AMAs，这些线粒体自身抗原与患者识别的相同。此外，小鼠线粒体自身抗体识别的表位与人类PBC患者相似，是内脂酰结构域，这些自身抗体也抑制酶的功能。此外，dnTGF2RII小鼠具有由CD4和CD8细胞组成的强烈门静脉周围炎症，以及类似于人PBC的血清细胞因子谱。本文研究的小鼠结构不同于一般的TGF-2-/-小鼠，其病理主要是溃疡性结肠炎。相比之下，dnTGF2RII小鼠存活超过6个月，只有轻微的溃疡性结肠炎，其主要病理表现在肝脏。重要的是，我们的数据表明，在缺乏必要的调节性T细胞影响的情况下，通过分子模仿等机制启动自身免疫并不会激活固有的自反应性T细胞库。我们建议利用dnTGF2RII小鼠对免疫系统进行详细的个体发生分析，以确定特定谱系促进疾病过程的动力学。我们将通过分析先天、体液和细胞免疫系统、肝淋巴亚群、肝脏组织病理学和自身抗体产生动力学来研究小鼠模型的免疫学方面。我们还将过继性地从dnTGF2RII小鼠中转移分离的CD4+和/或CD8+ T细胞，以研究涉及门道炎症的T细胞效应机制。此外，我们将确定在缺乏B细胞的自然历史和免疫病理。我们的目标是扩展我们的试点数据，以严格确定该模型对人类PBC的有效性，并使未来的研究集中在PBC的机制和潜在治疗上。

DESCRIPTION (provided by applicant): Primary biliary cirrhosis (PBC) is a liver specific autoimmune disease, characterized by portal tract lymphocytic infiltration, selective destruction of biliary epithelial cells and the presence of anti-mitochondrial antibodies (AMAs). Advances in the study of PBC have been hampered by its cryptic onset, and limitations in accessing human liver. We have taken advantage of a mouse transgenic for directed expression of a dominant negative form of transforming growth factor (TGF)-2 receptor type II (dnTGF2RII), under the direction of the CD4 promoter, and demonstrated that these mice develop several key features of PBC including spontaneous production of AMAs directed to PDC-E2, BCOADC-E2 and OGDC-E2, the same mitochondrial autoantigens recognized by patients. In addition, the epitope recognized by murine mitochondrial autoantibodies, similar to human patients with PBC, is the inner lipoyl domain and these autoantibodies also inhibit enzyme function. Moreover, dnTGF2RII mice have intense periportal inflammation composed of CD4 and CD8 cells as well as a serum cytokine profile analogous to that of human PBC. The murine construct studied herein is distinct from generic TGF-2-/- mice whose pathology is primarily ulcerative colitis. In contrast, dnTGF2RII mice survive over 6 months with only minimal ulcerative colitis and their dominant pathology is manifest in liver. Importantly, our data point away from initiation of autoimmunity by mechanisms such as molecular mimicry towards activation of an intrinsically self-reactive T cell repertoire in which necessary regulatory T cell influences are lacking. We propose to perform a detailed ontogenetic analysis of the immune system to define the kinetics by which specific lineages contribute to the disease process by utilizing dnTGF2RII mice. We will study the immunological aspects of the mouse model by analyzing the innate, humoral and cellular immune systems, liver lymphoid subpopulations, liver histopathology and kinetics of autoantibody production. We will also adoptively transfer isolated CD4+ and/or CD8+ T cells from dnTGF2RII mice to address T cell effector mechanisms involved in portal tract inflammation. In addition, we will determine the natural history and immunopathology in the absence of B cells. Our goal is to extend our pilot data to rigorously determine the validity of this model for human PBC and to enable focused future studies directed at mechanisms and potential therapy for PBC.