Translational studies of the induction and functional role of Th2 polarized CD4+ T-cells in chronic liver damage and hepatic fibrogenesis

免疫机制在肝脏炎症和随后的纤维化和肝硬化中起关键作用。广泛的研究已经揭示，先天性和适应性免疫系统的细胞组分的浸润和局部活化是引发促纤维化级联反应的先决条件。 这是临床相关的，因为尽管迫切需要有效的抗纤维化治疗，但治疗选择仍然有限。在其他器官如肺中的研究表明，CD 4 + T辅助细胞的Th 2极化与重塑过程直接相关。在器官纤维化过程中，包括IL-4和IL-13在内的典型Th 2细胞因子激活间充质细胞，间充质细胞合成大量的细胞外基质化合物。因此，软组织逐渐被结缔组织取代，最终导致器官衰竭。此外，Th 2细胞可以通过细胞-细胞相互作用诱导交替活化的M2巨噬细胞，其也显示促纤维化特性，由此器官纤维化进一步放大。然而，它仍然是广泛未知的，是否Th 2纤维化范例也适用于肝脏。有强有力的证据表明，Th 2-poalrized CD 4 + T细胞在寄生虫性肝病中起关键作用，但它们在无菌、抗原非依赖性肝脏炎症中的作用仍然难以捉摸。这个翻译项目的目的是在肝纤维化的不同阶段解剖T辅助细胞的分化，并在描述性和功能性研究中检查它们对基质沉积的贡献。在全面收集具有不同潜在病因的肝硬化病变组织标本的帮助下，将有可能精确地表征肝纤维化中的肝内T细胞谱和局部免疫环境。在体外细胞培养试验与原代人类细胞将允许研究肝脏募集和局部诱导的Th 2分化的辅助性T细胞的机制。 分析CD 4 + T细胞与肝实质和非实质细胞之间的相互作用将是本项目人类部分的主要重点。所获得的结果将在实验性抗原非依赖性肝纤维化模型中得到验证。在纤维发生期间的规定时间点，将表征浸润T细胞的特征。具有Th 2关键成分遗传缺陷的敲除动物将用于研究这种免疫应答在肝纤维化中的功能相关性。如果这些动物表现出较少的纤维化，则计划过继转移CD 4 + T细胞以阐明该细胞类别或先天免疫系统的成员，例如先天淋巴样细胞或NKT细胞，其也可以分泌Th 2相关细胞因子，基本上促进肝纤维化。通过促进我们对肝纤维化发病机制的理解，该项目可能有助于开发新的治疗工具来对抗肝硬化。

Immune mechanisms are critically involved in liver inflammation and subsequent fibrogenesis and cirrhosis. Extensive research has unravelled that the infiltration and local activation of cellular components of the innate as well as the adaptive immune system are prerequisites for the initiation of profibrotic cascades. This is clinical relevant because the therapeutical options are still limited despite the urgent need for effective antifibrotic treatments. Studies in other organs such as the lung have shown that the Th2 polarization of CD4+ T-helper cells is directly linked to remodeling proceses. During organ fibrosis prototypical Th2 cytokines including IL-4 and IL-13 activate mesenchymal cells which synthesize abundant amounts of extracellular matrix compounds. As a consequence, parenchyma is gradually replaced by connective tissue eventually leading to organ failure. Furthermore, Th2-cells can induce alternatively activated M2 macrophages ,that also display profibrotic properties, through cell-cell interaction, whereby organ fibrosis is further amplified. However, it is still widely unknown, whether the Th2-fibrosis paradigm also applies to the liver. There is robust evidence that Th2-poalrized CD4+ T-cells are critically involved in parasitic liver diseases, but their role in sterile, antigen-independent liver inflammation remains elusive. Aim of this proposed translational project is to dissect the differentiation of T-helper cells at different stages of liver fibrosis and to examine their contribution to matrix depostion in descriptive and functional studies. With the help of a comprehensive collection of tissue specimens of explanted diseased liver with different underlying etiologies, it will be possible to precisely characterize intrahepatic T-cell profiles and the local immune environment in liver fibrosis. In vitro cell-culture assays with primary human cells will allow to study mechanisms of hepatic recruitment and local induction of Th2 differentiated T-helper cells. The analysis of the reciprocal interplay between CD4+ T-cells and liver-resident parenchymal and non-parenchymal cells will be a major focus in the human part of this project. The obtained findings will be validated in experimental antigen-independent liver fibrosis models. At defined time points during fibrogenesis the signature of infiltrating T-cells will be characterized. Knockout animals with a genetic deficiency of Th2 key components will serve to study the functional relevance of this immune response in liver fibrosis. If these animals exhibit less fibrosis adoptive transfer of CD4+ T-cells is planned to unravel whether this cell class or members of the innate immune system, such as innate lymphoid cells or NKT-cells, which can also secrete Th2-related cytokines, essentially booster heptic fibrogenesis. By promoting our understanding of the pathogenesis of liver fibrosis this project may help to develop novel therapeutic tools to combat liver cirrhosis.