醛固酮通过caveolin-1介导的非基因组效应对HSC收缩、肝窦血管生成和重构的调节作用：门脉高压调控的新途径

In liver fibrosis, the level of aldosterone significantly upregulates and induces oxidative stress which initiatively contributes to angiogenesis and reconstruction of liver sinusoids. Non-genomic effect mediated by caveolin-1 (CAV-1) is the important manner regulated by aldosterone. Through this way, aldoterone could rapidly induced angiogenesis and oxidizing reaction in heart and kidney. However, the reports about how to regulate portal hypertension have not been found. Our previous study showed that aldosterone could induce hepatic stellate cells (HSCs) contraction, upregulate the expressions of CAV-1, PDGF, VEGF and then potentially promoted angiogenesis and reconstruction in liver sinusoids. Thus, we supposed that aldosterone induced hepatic oxidative stress which caused HSCs contraction, liver sinusoids angiogenesis and reconstruction via non-genomic effect mediated by CAV-1. We would investigate the regulation mechanism integrated HSC with LSEC of aldosterone including HSC contraction, the preservation of LSEC phenotype and nitric oxide (NO) synthesis, LSEC migration and vascular neogenesis, HSC chemotaxis and neogenesis stabilization. These results would provide novel strategy for regulation mechanism of aldosterone on portal hypertension.

肝纤维化状态下，肝内醛固酮（Aldo）水平显著上调，它所诱发的氧化应激反应是肝窦血管生成和重构的始动因素。小窝蛋白-1（CAV-1）介导的非基因组效应是Aldo的重要调节方式，具有快捷、高效的特点，是近年的研究热点。Aldo可通过该途径诱导心脏和肾脏氧化应激反应及血管生成，但是否影响门脉高压尚不明确。本前期研究发现：Aldo可诱导HSC收缩、促进CAV-1表达，具有增强PDGF、VEGF促肝窦血管生成和重构的潜能。本研究紧密围绕"Aldo经CAV-1介导的氧化应激反应促使HSC收缩、肝窦血管生成和重构" 这一假说，以紧密相关的肝星状细胞（HSC）和肝窦内皮细胞（LSEC）为一整体，从体内、外层面探讨Aldo通过CAV-1介导的氧化应激反应对HSC收缩、LSEC表型及NO生成、LSEC迁移及血管新生、HSC趋化及稳定新生血管的调控机制。本研究为拓展Aldo在门脉高压的调控机制提供新思路。

本课题从体内、外探讨醛固酮对肝星状细胞（HSC）激活、收缩和肝窦内皮细胞（LSEC）去窗孔、肝窦毛细血管化的影响及其机制。深入研究醛固酮通过Cav1介导的非基因组效应影响NLRP3炎症小体和自噬，进而调节HSC收缩、LSEC去窗孔化和肝窦血管生成的分子机理。体内研究发现，肝纤维化患者血清醛固酮较正常人显著升高，其肝组织MR（盐皮质激素受体）、Cav1和LC3均在肝窦高表达。胆管结扎（BDL）大鼠肝内Cav1表达、氧化应激和自噬随着HSC增殖和LSEC去窗孔化而增加；醛固酮拮抗剂螺内酯、抗氧化剂或自噬抑制剂作用后，Cav1表达、氧化应激和自噬水平下降，HSC活化及收缩减少、LSEC去窗孔化减轻，肝纤维化程度得以缓解。此外，我们首次发现持续注入醛固酮可促进LSEC去窗孔化和HSC增殖，Cav1表达、氧化应激和自噬水平升高；螺内酯或自噬抑制剂可抑制自噬和氧化应激，维持LSEC窗孔，提示醛固酮通过Cav1介导氧化应激和自噬促进肝纤维化形成。体外研究发现，醛固酮刺激HSC或LSECs后，可通过Cav1募集NOX4和MR到小窝，调控下游通路：一方面，通过上调NLRP3炎症小体诱导HSC收缩、迁移；另一方面，激活AMPK-ULK1-依赖的自噬通路促使骨架重构，并抑制NO/eNOS/sGC/cGMP/PKG通路，促进LSEC去窗孔化和毛细血管形成。螺内酯或依普利酮及抗氧化剂通过下调氧化应激和炎症小体相关蛋白，从而减轻HSC的活化；同时也下调自噬水平从而维持LSEC窗孔。自噬抑制剂3MA和巴弗洛霉素可通过抑制自噬并减轻氧化应激维持LSEC窗孔。但醛固酮如何通过炎症小体调控HSC的胶原生成？为何自噬促进剂和抑制剂均能减轻肝纤维化等科学问题有待进一步深入研究。结论：醛固酮通过Cav1/MR介导的氧化应激反应，上调HSC NLRP3炎症小体以及LSEC的自噬水平， 进而促进HSC活化、迁移、收缩以及LSEC去窗孔化及肝窦毛细血管化，最终加剧肝纤维化及导致门脉高压的发生。