肺动脉高压内皮损伤中CPT1对ROS调控线粒体自噬和凋亡的影响

Pulmonary arterial hypertension (PAH), characterized by pulmonary vascular remodeling, is a common clinical syndrome. Pulmonary aterial endothelium injury is considered to be the primary alternation that initiates the sequence of events resulting in PAH. However, the underlying mechanism is still unknown. Our previous metabomonic study demonstrated that alternation of glucose and fatty acid metabolic patterns and increased fatty acid oxidation in sera of monocrotaline-induced PAH rats. Furthermore, we found that the rate-limiting enzyme of fatty acid oxidation carnitine palmitoyltransferase (CPT)1 was upregulated in PAH rat lungs. It has been known that CPT1 is involved in the production of reactive oxygen species (ROS) and ROS plays a pivotal role in regulation of mitophagy and apoptosis. As a result,we hypothesized that enhanced fatty acid oxidation which caused the imbalance of mitophagy and apoptosis in mitochondria by overactive ROS reaction induced pulmonary arterial endothelium injury and promoted pulmonary vascular remodeling. This study will focus on the relationship of CPT1 and ROS, the mechanism and relationship of that ROS regulated mitophagy and apoptosis in occurrence and development of PAH, and possibility of CPT1 being a the target of prevention and management of PAH in monocrotaline-induced PAH rats, CPT1 deficieng mice and pulmonary arterial endothelium cells.

肺动脉高压（PAH）是临床上常见的病理生理综合征，肺血管重构是主要病理变化，肺动脉内皮损伤是起始环节，但机制细节尚不明了。我们前期的代谢组学研究发现野百合碱诱导的PAH大鼠血清脂肪酸氧化增强，肺组织中脂肪酸氧化的关键限速酶肉碱棕榈酰转移酶（CPT）1表达增加。已知CPT1参与活性氧簇（ROS）产生的调控，且ROS诱导线粒体自噬和凋亡调控中起重要作用。我们假设：线粒体中脂肪酸氧化增强，通过过度的ROS反应，引起线粒体自噬和凋亡的失衡，导致肺动脉内皮损伤，促进肺血管重构。本项目以野百合碱诱导的肺动脉高压大鼠、CPT1基因敲除小鼠和肺动脉内皮细胞为对象，在整体与细胞两个层面研究PAH发生过程中CPT1与ROS的关系，ROS调节线粒体自噬和凋亡的机制及与PAH发生和发展的关系，探索以CPT1作为防治PAH靶点的可能性。

肺动脉高压（PAH）是临床上常见的病理生理综合征，PAH 的主要病理性改变包括肺血管重构和肺血管张力升高，其中 PASMCs（pulmonary artery smooth muscle cells，肺动脉平滑肌细胞）的异常增殖和迁移在肺血管重构中起主导性作用，但机制细节尚不明了。在该项目的支持下，我们建立了慢性PAH模型通过野百合碱一次性20mg/kg一周两次腹腔内注射两种给药方式都可以建立 PAH 大鼠模型，存活率高，更接近人类慢性的 PAH 病程型。在该模型的基础上，我们发现在PAH进展过程中大鼠肺组织肉碱棕榈酰转移酶（carnitine palmitoyltransferase，CPT1）酶活性升高，ATP表达增多，磷酸化AMPK、p53和 p21的表达均有下降。在体外实验中，发现CPT1能在PASMCs中表达，并定位于线粒体。PDGF-BB干预可上调 CPT1 的表达，呈浓度和时间依赖性，促进细胞增殖。PDGF-BB同时能够促进 ATP 的生成，抑制 AMPK 的磷酸化，降低p53和p21的表达，细胞周期G0/G1期比例减少，G2/M比例增加，这些作用能被CPT1抑制剂 Etomoxir所逆转。而过表达 CPT1 则能够促进 PASMCs 增殖，促进 ATP 的生成，抑制 AMPK 的磷酸化、p21和p53的表达水平。因此，CPT1 可通过AMPK-p53-p21 途径调控PASMCs增殖。CPT1可能可以作为防治PAH靶点。