Modulators of hepatic response to TGF-ß mediated cellular injury in inbred mice: Identification of modifiers of fibrosis susceptibility

肝纤维化是慢性肝损伤的非特异性反应，两种最常见的原因是病毒性肝炎或酒精滥用。双胞胎研究和种族差异表明，遗传因素在这两种类型的易感性和进展中起作用。与病毒性肝炎相反，迄今尚未发现遗传变异与酒精性肝纤维化易感性之间的确切联系。转化生长因子(TGF)-β被认为是主要的促纤维化细胞因子，在各种损伤模式下驱动纤维化。这一核心作用使得对TGF-β介导的肝损伤反应的每个修饰位点都成为纤维化易感性的候选基因。本项目的目的是利用从遗传上不同的近交系小鼠株分离的肝细胞，鉴定TGF-β介导的损伤的修饰基因。肝细胞对TGF-β高度敏感。它们的死亡导致Kupffer细胞的激活和随后的炎症细胞因子的释放，以及肝星状细胞的激活，生长因子和细胞外基质成分的表达增强。在这里，我们提出利用小鼠自交系C57BL/6J和DBA/2J的后代产生的遗传参考群体，也被称为BXD重组自交系。来自这些小鼠系的基因不同的肝细胞将被TGF-β刺激，表型差异（细胞损伤，基因表达）将被量化以描述反应的差异。数量性状位点定位，即BXD面板中的连锁分析，将使我们能够通过等位基因变异确定对TGF-β的差异反应的遗传位点。这个实验框架将允许我们评估在确定的人类队列中对纤维形成易感性贡献的同源人类区域和候选基因。

Hepatic fibrosis is a non-specific response to chronic liver injury, the two most common causes being viral hepatitis or alcohol abuse. Twin studies and ethnic differences indicate that genetic factors play a role in predisposition to and progression of both types. In contrast to viral hepatitis, no firm associations between genetic variants and susceptibility to alcoholic liver fibrosis have been identified to date. Transforming growth factor (TGF)-β is considered the master pro-fibrogenic cytokine, driving fibrosis in response to various modes of injury. This central role makes every modifier locus of the response to TGF-β mediated hepatic injury a candidate gene for fibrosis susceptibility. The aim of this project is to identify the modifier genes of TGF-β mediated injury, using hepatocytes isolated from genetically distinct inbred mouse strains. Hepatocytes are highly responsive to TGF-β. Their demise leads to activation of Kupffer cells and subsequent release of inflammatory cytokines as well as activation of hepatic stellate cells with enhanced expression of growth factors and extracellular matrix components. Here, we propose to avail of a genetic reference population generated from progeny of inbred mouse lines C57BL/6J and DBA/2J, also known as BXD recombinant inbred lines. The genetically distinct hepatocytes from these mouse lines will be challenged with TGF-β, and phenotypic differences (cellular damage, gene expression) will be quantified to delineate differences in response. Quantitative trait locus mapping, i.e. linkage analysis in the BXD panel, will enable us to identify the genetic loci that underlie differential responses to TGF-β by allelic variation. This experimental framework will allow us to assess the orthologous human regions and candidate genes for contribution to fibrogenesis susceptibility in defined human cohorts.