VEGF/PDGF在门静脉高压症侧支形成及内脏高动力循环中的作用及其作为治疗的新靶点研究

Pathological angiogenesis plays an important role in the pathogenesis of portal hypertension. The formation of portal-systemic collaterals and hyperdynamic splanchnic circulations in portal hypertension patients could be regulated by several vascular growth factors. Thus, anti-angiogenic treatment (molecular target therapy) might be a promising therapeutic strategy to prevent the progress of portal hypertensive syndrome. Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) pathways are crucial to angiogenesis, a process that contributes significantly to the pathogenesis of portal hypertension. The aims of this study include to investigate the correlation between VEGF and/or PDGF signaling and the formation of hyperdynamic splanchnic circulation and portosystemic collateralization in rats with developing or established portal hypertension, and to determine the effects of VEGF and/or PDGF signaling in two etiologically different portal hypertension models. In order to achieve these, we have designed following procedures. At first, we will establish an experimental model of portal hypertension in Sprague-Dawley rats through partial portal vein ligation or common bile duct ligation. These rats will then be randomly grouped and treated with Avastin (VEGF signaling inhibitor), Gleevec (PDGF signaling inhibitor), or both simultaneously when portal hypertension is developing or is already fully developed. Finally, the expression of splanchnic angiogenesis mediators, splanchnic hemodynamics, the extent of portosystemic collaterals and the extent of hepatic fibrosis will be observed. Our results will provide new insights into how angiogenesis regulates portal hypertension by demonstrating that the maintenance of increased portal pressure, hyperkinetic circulation, and portosystemic collateralization are regulated by VEGF and PDGF in portal hypertensive rats. Importantly, these findings will suggest that an extended anti-angiogenic strategy (targeting VEGF/PDGF) may be a novel approach to the treatment of portal hypertension.

新生血管生成是门静脉高压症（PH）形成和发展的重要机制，门体侧支和内脏高动力循环形成可能受多种促血管生长因子调控，以控制血管生成为目的的分子靶向治疗可能成为预防或逆转PH的新方法。本课题基于血管内皮生长因子（VEGF）和血小板衍生生长因子（PDGF）在血管生成中的不同作用机制，在建立不同病因PH大鼠实验模型基础上，以PH形成的不同时间点，检测内脏组织VEGF、PDGF表达水平的动态变化和差异；并分别给予大鼠VEGF抑制剂Avastin、PDGF抑制剂Gleevec和联合用药，检测三种给药条件对大鼠内脏血管生成相关因子表达水平、门体侧支分流程度、内脏高动力循环状况和肝纤维化的影响，探讨PH形成过程中和完全形成后，VEGF、PDGF信号通路在门体侧支和内脏高动力循环形成中的作用，并以其为靶点治疗PH的可行性。本研究将揭示PH形成的不同阶段所受血管因子调控的分子机制，为分子靶向治疗PH提供基础。

门静脉高压症（PH）是以门静脉系统血流动力学异常变化为主要特征的一组临床综合征，是肝硬化的重大并发症和致死的主要原因。新生血管生成是门静脉高压症形成和发展的重要机制，以控制血管生成相关因子为目的分子靶向治疗可能成为预防或逆转门静脉高压症的新方法。（1）本课题构建了门静脉高压症大鼠实验模型，并研究了在门静脉高压症形成过程中， VEGF、 PDGF联合阻断对门静脉压力水平的影响，结果发现联合阻断VEGF、 PDGF对于降低PH动物门静脉压力水平的效果欠佳，不足以达到明显降低门静脉高压的作用，提示我们以VEGF、 PDGF作为靶点治疗门静脉高压症的效果可能并不理想。（2）研究中我们发现了介导肝窦血管内皮功能紊乱的缩血管因子通路COX-1/TXA2在调控肝硬化门静脉高压症中的作用。我们成功地构建了四氯化碳诱导的肝硬化门静脉高压症小鼠模型，并利用纳米靶向性基因沉默技术（HA-PEI/COX-1 siRNA），精准调控肝窦血管内皮细胞COX-1/TXA2通路，成功地降低了肝硬化门脉高压症小鼠的门静脉压力，并改善其脾功能亢进指标，达到了预期的研究结果。该研究揭示了门静脉高压症（PH）形成中所受血管因子调控的分子机制，为分子靶向治疗PH提供了前期基础。课题组在国际上首次成功地将靶向肝窦血管内皮细胞的纳米基因治疗（HA-PEI/COX-1 siRNA）应用于肝硬化门静脉高压症的靶向治疗中。我们采用的纳米生物材料为非病毒性基因载体，其高效的基因输送效能，良好的生物兼容性以及低毒性使其具备良好的临床应用前景。（3）在门静脉高压症研究过程中，我们发现炎症反应与肝纤维化的发生发展密切相关。我们选取具备强效抗炎作用的中药单体穿心莲内酯应用于肝纤维化的治疗，成功地降低肝脏炎症反应进而改善了肝纤维化，为通过调控炎症反应来治疗肝纤维化提供了思路和方向。