dnTGF Beta RII Mice and PBC

描述（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，以门道淋巴细胞浸润、胆道上皮细胞选择性破坏和抗线粒体抗体（AMAs）为特征。我们的实验室在推进PBC研究方面发挥了重要作用，这项工作始于近25年前的线粒体自身抗原的鉴定和克隆。然而，PBC的突破需要动物模型，在过去的几年里，我们的实验室已经描述了几个这样的模型。然而，该模型在更大程度上概括了人类PBC的特征，是在CD4启动子的指导下直接表达TGF2受体II型显性阴性形式（dnTGF2-RII）的转基因小鼠。利用R21奖励的资金，我们已经报道了dnTGF2-RII小鼠产生与人类相同特异性的ama，在血清和肝脏中具有相似的细胞因子谱，并且具有与PBC患者相似的肝脏组织学和免疫组织化学。此外，脾脏dnTGF2-RII CD8+ T细胞过继转移到B6 Rag1-/-小鼠体内可转移自身免疫性胆管炎，而dnTGF-2RII CD4+ T细胞的类似转移可转移结肠炎。我们建议利用这些和其他数据，作为R21奖项的合理延伸，广泛剖析导致胆道自身免疫性疾病的免疫致病机制。我们特别提出了三个关键目标。首先，我们已经证明dnTGF2-RII CD8+ T细胞足以将胆道病理转移到Rag1-/-受体，我们建议通过转移和混合骨髓嵌合研究以及CD8+ T细胞的个体发生分析和CD8+ T细胞细胞因子表达分析来确定dnTGF2-RII CD8+ T细胞介导的疾病的机制。其次，我们将利用我们在I类四聚体技术方面的专业知识，并通过使用TCR库受限的dnTGF2-RII小鼠，确定dnTGF2-RII CD8+ T细胞自身免疫是否具有抗原特异性。最后，我们最近发表了在dnTGF2- RII小鼠中删除IL-12p40而不是IFN-3可以防止疾病的发展。鉴于最近在人类PBC全基因组关联研究中显示的IL-12多态性，这是令人兴奋的。我们将利用我们生产独特小鼠结构的能力，我们将剖析产生疾病的细胞因子介导途径。我们将把p35-/-小鼠（缺乏IL-12）、p19-/-小鼠（缺乏IL-23）、p35/19-/-小鼠（缺乏IL-12和IL-23）、p35/40- /-小鼠（缺乏IL-12、IL-23和同二聚体IL-12p40）或p35/IL-17A-/-小鼠（缺乏IL-12和IL-17A）小鼠与dnTGF-2RII小鼠回交。此外，由于血清IL-22在dnTGF-2RII小鼠中显著升高，我们还将IL-22-/-小鼠回交到dnTGF-2RII小鼠上，以进一步确定IL-22的保护或炎症作用。我们认为，使用我们独特的小鼠结构和我们在该模型中对自身免疫性胆管炎机制的严格解剖将为成功调节人类PBC提供重要线索。

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 antimitochondrial antibodies (AMAs). Our lab has been instrumental in advancing the study of PBC, work which began nearly 25 years ago with the identification and cloning of the mitochondrial autoantigens. However, a breakthrough in PBC requires an animal model and over the past several years our laboratory has described several such models. However, the model which recapitulates in greater similarity the features of human PBC, is a mouse transgenic for directed expression of a dominant negative form of TGF2 receptor type II (dnTGF2-RII) under the direction of the CD4 promoter. Using funds from an R21 award that led to the development of this model, we have reported that dnTGF2-RII mice develop AMAs of the identical specificity as humans, similar cytokine profiles in both sera and liver and have liver histology and immunohistochemistry similar to humans with PBC. Further, adoptive transfer of splenic dnTGF2-RII CD8+ T cells into B6 Rag1-/- mice transfers autoimmune cholangitis, whereas similar transfer of dnTGF-2RII CD4+ T cells transfers colitis. We propose to take advantage of these and other data, a logical extension of our R21 award to extensively dissect the immunopathogenic mechanisms that lead to biliary autoimmune disease. In particular, we propose three critical aims. Firstly, we have demonstrated that dnTGF2-RII CD8+ T cells are sufficient to transfer biliary pathology to Rag1-/- recipients and we propose to define the mechanism of dnTGF2-RII CD8+ T cell mediated disease using transfer and mixed bone marrow chimeric studies and an ontogenetic analysis of CD8+ T cells and an analysis of CD8+ T cell cytokine expression. Secondly, we will define whether dnTGF2-RII CD8+ T cell autoimmunity is antigen specific by taking advantage of our expertise in class I tetramer technology and by using dnTGF2-RII mice with a restricted TCR repertoire. Finally, we have recently published that deleting IL-12p40, but not IFN-3, in dnTGF2- RII mice prevents the development of disease. This is exciting in light of recent IL-12 polymorphism demonstrated in genome-wide association studies of human PBC. We will take advantage of our ability to produce unique murine constructs and we will dissect the cytokine mediated pathways that produce disease. We will backcross p35-/- mice (lack IL-12), p19-/- mice (lack IL-23), p35/19-/- mice (lack IL-12 and IL-23), p35/40- /- mice (lack IL-12, IL-23, and homodimeric IL-12p40), or p35/IL-17A-/- mice (lack IL-12 and IL-17A) mice to dnTGF-2RII mice. Furthermore, as sera IL-22 is significantly elevated in dnTGF-2RII mice, we will also backcross IL-22-/- mice onto dnTGF-2RII mice to further define the protective or inflammatory role of IL-22. We submit that use of our unique murine constructs and our rigorous dissection of the mechanism of autoimmune cholangitis in this model will provide important clues towards successful modulation of human PBC. PUBLIC HEALTH RELEVANCE: Primary biliary cirrhosis is a cryptic autoimmune disease of humans characterized by autoantibodies and inflammation of the biliary system of the liver. Progress in this disease has been hampered by the absence of an animal model. Our lab proposes to take advantage of a model that recapitulates many of the features of human PBC and study the mechanisms of disease with the belief that such data will lead to a breakthrough in human PBC.