Hedgehog信号通路在肝窦内皮细胞介导血管重构致肝硬化中的调控作用

Role of hepatic vascular pathological remodeling in the pathogenesis of cirrhosis is currently an attractive research area in the international hepatology community. Accumulating evidence indicates that Hedgehog (Hh) pathway is critical for regulation of in vivo vascular homeostasis. Liver sinus endothelial cells (LSECs) play a pivotal role in maintenance of hepatic vascular homeostasis. However, the role of Hh signaling in LSECs-involved cirrhosis and the underlying mechanisms have not been reported yet. Our previous experiments showed that LSECs were responsive cells to Hh pathway. Therefore, we for the first time propose that Hh pathway could be a core pathway for modulating hepatic vascular remodeling and formation of cirrhosis. The current program will first establish two kinds of cirrhosis models in rats to examine the activation statues of Hh signaling and its relevance to cirrhosis. Then the specific agonists and inhibitors of Hh pathway, siRNA-mediated gene knockdown and Smo-/- mice with experimental cirrhosis will be employed in accordance with the forward or reverse genetics to explore the effects of Hh pathway on LSEC angiogenesis and on related angiogenic processes during cirrhosis in vivo and in vitro. Next, HiF-1α conditional knockout mice will be used to elucidate the mechanisms underlying Hh signaling modulation of LSEC-mediated cirrhosis vascular remodeling. The results of these studies will uncover new mechanisms of cirrhosis pathology and provide novel therapeutic targets for cirrhosis treatment, which are of high theoretic and clinical values.

肝脏血管病理性重构在肝硬化病理机制中的作用是当前国际研究热点。既往研究发现Hedgehog（Hh）通路在机体血管稳态的调控中具有重要作用，肝窦内皮细胞（LSEC）是维持肝脏血管稳态的关键细胞，但Hh通路与LSEC在肝硬化病变中作用及机制尚未见报导。我们预实验结果显示LSEC是Hh通路的效应细胞，据此我们首次提出：Hh通路可能是LSEC介导肝脏病理性血管重构与肝硬化形成的关键调控途径。本项目拟先以大鼠建立两种肝硬化模型，体内外考察Hh通路活化状态与肝硬化的相关性；再利用Hh通路特异性调控剂、基因沉默技术、Smo-/-小鼠肝硬化模型等正向及反向遗传学研究手段，体内外揭示肝硬化时Hh通路对LSEC的促血管新生及相关因子的调控作用；并利用HiF-1α条件性敲除小鼠深入揭示Hh对LSEC介导的肝硬化血管重构的分子机制，为深入阐释肝硬化的发病机制及为肝硬化治疗提供新靶标，具有重要的理论意义与应用价值。

肝脏血管病理性重构在肝纤维化病理机制中的作用目前是当前国际研究热点。已有研究表明Hedgehog（Hh）通路在机体调控血管稳态中发挥了重要作用，肝窦内皮细胞（LSEC）是构成肝脏微血管的关键细胞。本项目阐明了LSEC介导的肝脏血管病理性重构在肝纤维化病理机制中的作用，以及Hh信号通路活化能够诱导LSECs发生毛细血管化和病理性血管生成的作用及分子机制。实验结果显示Hh信号通路活化能够促进核转录因子HIF-1α及其下游促血管生成因子的表达。进一步深入研究发现YAP（Yes-associated protein）能够增强HIF-1α入核，参与LSEC血管生成。Hh信号通路活化能够促进同源蛋白PROX1的表达，通过招募去泛素化酶USP19抑制HIF-1α的降解，细胞质中HIF-1α大量积累，入核后激活下游VEGF-A，PDGF-BB和Angiopoietin-2等促血管生成因子大量表达，诱导LSECs血管生成，从而引起肝纤维化的作用。本研究为深入阐释肝纤维化的发病机制及为肝纤维化治疗提供新靶标，具有重要的理论意义与应用价值。