减阻剂通过调控切应力对肺动脉高压的作用及其机制

Pulmonary hypertension is the key pathological changes of a variety of cardiopulmonary diseases, characterized by a progressive and fatal disease which seriously affects human’s health. .There have been no effective methods or medicines to cure pulmonary hypertension until now. Reducing pulmonary artery resistance is the key to prevent and treat pulmonary hypertension .Drag-reducing polymers (DRPs) are blood-soluble macromolecules that can increase blood flow and reduce vascular resistance. Our previously work has found that DRPs can significantly increase the internal diameter of small pulmonary arteries, reduce medial wall thickness and vascular resistance of pulmonary arteries, ultimately leading to the decline of pulmonary artery pressure,but the mechanism is not clear.Pulmonary hypertension model of rats, pulmonary vascular ring model in vitro, and Bioflux 200 shear microfluidic cell culture system are chosen in this study. Therefore，the study aims at researching DRPs inhibiting cell skeleton reconstruction．Taking the key protein which induces cytoskeletal remodeling--RLC phosphorylation as the breakthrough point ,the study focuses on the two key pathways of DRPs inducing phosphorylation of RLC ：MLCK pathway and ROCK kinase pathway．The study is designed to investigate the roles and mechanisms of DRPs in regulating hemodynamics of pulmonary hypertension.DRPs may offer a new potential approach for the treatment of pulmonary hypertension, which may has theoretical significance and application value to society.

肺动脉高压是多种心肺疾病发生发展的关键病生环节，是一类严重威胁人类健康的进展性和致命性疾病，目前尚无有效治疗方法。减低肺动脉阻力是预防和治疗肺动脉高压的关键介入点。减阻剂是一类可以降低流体阻力作用的高分子聚合物。前期研究发现，减阻剂可以显著减低肺血管阻力、降低肺小动脉血管壁厚度、并增加肺小动脉内径，从而降低肺动脉压力,但是机制不明。本研究通过大鼠肺动脉高压模型、离体肺动脉血管环模型、Bioflux200控剪切力微流通道细胞培养技术，从血流切应力角度分析减阻剂改善肺动脉内皮细胞骨架重构为目的，从诱导细胞骨架重构的关键蛋白—调节轻链(RLC)的磷酸化为切入点，研究减阻剂对介导RLC磷酸化的两条关键通路：MLCK和ROCK信号途径的干预作用，探讨减阻剂改善肺动脉高压血流动力学的作用机制。本研究将对肺动脉高压的防治提供一种新思路，其成果必将具有一定的理论意义和应用价值。

肺动脉高压(pulmonary hypertension，PH)是指肺动脉压力超过一定界值的血流动力学异常状态，是多种心肺疾病发生发展的关键病生环节，预后差，病死率高，是一类涉及多个学科的严重威胁人类健康的进展性和致命性疾病。目前尚无有效治疗方法。减低肺动脉阻力是预防和治疗肺动脉高压的关键介入点。减阻剂是一类可以降低流体阻力作用的高分子聚合物。前期研究发现，减阻剂可以显著减低肺血管阻力、降低肺小动脉血管壁厚度、并增加肺小动脉内径，从而降低肺动脉压力,但是机制不明。本研究第一部分目的是探讨DRPs对低氧性肺动脉高压血流动力学的作用。雄性Wistar大鼠随机分为4组(I组:常氧+生理盐水;II组:常氧+ PEO, III组:低氧+生理盐水，IV组:低氧+ PEO).4周后，分别比较以下几个方面:平均肺动脉压(mPAP)、右心室收缩压(RVSP)、右心室肥厚、肺动脉干壁厚、右心室肥厚指数、心肌细胞横截面积(CM CSA)及右心室超微结构。与组1、组2比较，组3组和组4肺动脉主干内外侧膜增厚，但是组3和组4之间肺动脉主干内侧壁厚度无统计学差异。这些结果表明PEO在低氧状态下作用机制主要是改善肺小肺动脉的重构，而不是肺动脉主干的重构。本实验第二、三部分采用Bioflux200控剪切力微流细胞培养系统探讨低切应力对肺动脉内皮细胞骨架重排的调控作用和其作用机制。1dyn/cm2低切应力诱导的钙离子荧光强度明显高于10dyn/cm2切应力干预组（P<0.05）。减阻剂PEO干预后，低切应力PEO处理组较单纯低切应力组荧光强度明显下降。1dyn/cm2低切应力刺激后肺动脉内皮细胞TRPC1相对表达量较正常对照组和10dyn/cm2切应力刺激组升高，加入减阻剂PEO处理后，低切应力PEO处理组较单纯低切应力组钙转运蛋白（TRPC1）表达下降。低切应力干预后，F-actin、MLCK、ROCK表达显著升高(p<0．05)，说明低切应力可以显著诱导细胞骨架相关蛋白表达。在PEO干预下，可以显著抑制低切应力组诱导F-actin、MLCK、ROCK等表达的作用。DRPs可能会提供一种新的潜在方法，对肺动脉高压的治疗具有一定的理论意义和社会应用价值。