内质网应激调控线粒体及炎症小体在高肺血流肺动脉高压中的机制研究

Pulmonary artery hypertension (PAH) is one of most common complications of congenital heart disease and causes an incurable progression to right ventricular failure and death. Recent studies demonstrated the endoplasmic reticulum stress (ERS)， mitochondria dysfunction and inflammasome were involved in triggering and maintaining pulmonary artery remodeling, however, most of previous studies were based on monocrotaline（MCT）or hypoxia-induced rat PAH models. The exact role of ERS, mitochondria dysfunction，inflammasome activation，and their contribution to pulmonary vascular remodeling (PVR) in congenital heart disease related high pulmonary blood flow PAH is still unclear. In previous studies, we have demonstrated that antioxidant substance may reduce the oxidative stress, NLRP3 inflammasome activation, inflammation and PVR in MCT induced-PAH, and that simvastatin may alleviate left common carotid artery to left external jugular vein shunt induced PAH. Our preliminary experiment showed that 4-PBA, as a ERS antagonist, can reduce PVR and pulmonary artery pressure in left common carotid artery to left external jugular vein shunt induced PAH rat model. This research project plans to continue the work above, aims to find out if ERS, mitochondria dysfunction and inflammasome activation participate in the progression of PVR and PAH via applying a modified high pulmonary blood flow rat PAH model (left common carotid artery to left external jugular vein shunt plus right pulmonary artery ligation). Our project is expected to reveal the mechanism of ERS-mediated mitochondrial dysfunction regulating inflammasome activation and inflammation in high pulmonary blood flow PAH. Evidences from this project will provide new insight in the pathophysiologic process of high pulmonary blood flow induced PAH, and facilitate to design novel therapeutic strategies.

肺动脉高压是先天性心脏病常见的并发症，严重影响患者的预后。内质网应激、线粒体功能障碍、炎症小体分别被报道参与了肺血管重塑和肺动脉高压的形成，但既往研究多是基于野百合碱或低氧诱发的动物模型。肺血流增加为特征的先心病相关肺高压的发病机制目前仍不明确。前期研究发现抗氧化物质能够抑制NLRP3炎症小体，缓解肺动脉高压；辛伐他汀能够降低颈动-静脉分流所致肺动脉高压。预实验显示内质网应激抑制剂4-PBA能够减轻颈动-静脉分流大鼠的肺动脉压力和肺血管重构。本课题拟延续以上研究，应用改良高肺血流大鼠肺动脉高压模型（颈动-静脉分流+右肺动脉结扎）更好的模拟先心病相关肺动脉高压；探究内质网应激、线粒体功能障碍、NLRP3炎症小体在高肺血流肺动脉高压中的作用机制；探索内质网应激-线粒体-炎症小体信号通路干预治疗肺动脉高压的可能性。研究目的旨在揭示高肺血流肺动脉高压发展的新机制，试图为药物研发提供新的理论依据。

研究背景：肺动脉高压(Pulmonary artery hypertension, PAH)以肺血管重构、肺动脉压力增高以及右心室肥厚为主要特征。内质网应激（Endoplasmic reticulum stress, ERS）在PAH的发生和发展中发挥着重要作用，直接或间接抑制ERS相关信号通路可以减轻低氧或MCT诱导PAH. 然而有关ERS在高肺血流PAH中的作用未见研究报道。本研究旨在探究4-PBA能否减轻右肺动脉结扎（Right pulmonary artery ligation, RPAL）+左颈总动脉-左颈外静脉（Left common carotid artery-left external jugular vein，LCCA-LEJV）分流大鼠PAH的发生发展过程。.材料方法：雄性Sprague-Dawley大鼠（8-10周，200-220g）随机分为Sham组、PAH组和4-PBA组。4-PBA组大鼠于RPAL+LCCA-LEJV术后第5-12周给予4-PBA (500mg/kg/d)。于术后12周对大鼠进行血流动力学评估、右心肥厚指数测算和肺组织学分析。RNA 测序分析应用于探究PAH大鼠肺组织mRNA及相关信号通路变化，分别运用Western Blot、免疫荧光技术测定肺组织中ERS信号通路的激活情况。.实验结果：RPAL+LCCA-LEJV成功诱导安慰剂治疗PAH组大鼠肺动脉高压形成，伴随肺组织、肺小动脉内ERS相关蛋白的激活。同PAH组相比，4-PBA可以降低右心室收缩期压力、减少肺小动脉血管壁中层增生和右心肥厚。并且，4-PBA干预能够下调肺组织中ERS相关蛋白（ATF-6, GRP78, PERK）的表达，降低炎症体通路相关蛋白(NLRP3、Caspase-1和IL-1β)的水平。.实验结论：ERS参与了先心病相关的高肺血流所致肺动脉高压的形成。4-PBA可以通过抑制肺小动脉壁平滑肌细胞的ERS反应，减轻RPAL+LCCA-LEVJ诱导的高肺血流肺动脉高压的发生和发展，下游通路可能涉及到炎症小体。