基于OAT1/3-MAPK级联/NFκB介导的尿毒素硫酸吲哚酚诱导心肌损伤的分子机制

Patients with chronic kidney diseases are at high risk for cardiovascular diseases, and more than 50% of deaths are due to cardiovascular events. Uremic toxin indoxyl sulfate accumulated in chronic kidney disease patients is an independent risk factor for cardiovascular events. However, the molecular mechanisms of myocardial injury caused by indoxyl sulfate have not been elucidated. We have previously found that the accumulation of indoxyl sulfate accelerates cardiac hypertrophy and interstitial fibrosis induced by chronic heart failure. Antagonist of organic anion transporter 1 and 3 (OAT1/3), probenecid, ameliorates the pro-hypertrophic and pro-fibrotic actions of indoxyl sulfate. All these indicate that OAT1/3 is associated with indoxyl sulfate-induced cardiac remodeling. Based on previous studies, rat model of 5/6 subtotal nephrectomy followed by ligation of left anterior descending coronary artery, and cell culture of cardiomyocytes and fibroblasts will be used in the present project to investigate the molecular mechanisms involved in myocardial injury induced by indoxyl sulfate. This project will report that indoxyl sulfate enters cardiac cells via OAT1/3, and activates intracellular reactive oxygen species, mitogen-activated protein kinase cascade and nuclear factor-kappa B，demonstrating that indoxyl sulfate induces renal-related myocardial injury by regulating oxidative stress. This project will clarify OAT1/3 as an important heart-kidney interaction target, and provide a new research approach for the prevention and treatment of uremic cardiomyopathy.

慢性肾脏病患者是罹患心血管疾病的高危人群，其中死于心血管疾病的患者占50%以上。慢性肾脏病患者体内积累的尿毒素硫酸吲哚酚是导致心血管疾病的独立危险因素，而硫酸吲哚酚诱导心肌损伤的分子机制尚未阐明。课题组前期研究发现，硫酸吲哚酚积累加剧慢性心力衰竭引起的心肌肥厚和间质纤维化，且有机阴离子转运蛋白1和3（OAT1/3）拮抗剂丙磺舒干预硫酸吲哚酚的促肥大和促纤维化作用，提示硫酸吲哚酚引起的心室重构与OAT1/3有关。基于以往工作基础，本课题将应用5/6肾切除合并左冠脉前降支结扎大鼠模型、原代心肌细胞和成纤维细胞模型，研究硫酸吲哚酚诱导心肌损伤的分子机制，报道硫酸吲哚酚经OAT1/3介导进入心肌细胞，并诱导细胞内活性氧生成，引起丝裂原活化蛋白激酶级联和核因子活化，阐明硫酸吲哚酚通过调控氧化应激，造成肾源性心肌损伤，揭示心、肾相互作用的重要靶点OAT1/3，为尿毒素心肌病的防治提供研究新思路。

慢性肾脏病患者是罹患心血管疾病的高危人群。 慢性肾脏病患者体内积累的尿毒素硫酸吲哚酚是导致心血管疾病的独立危险因素，而硫酸吲哚酚诱导心肌损伤的分子机制尚未阐明。本项目通过对大鼠行5/6肾切除合并左冠脉前降支结扎，构建Ⅳ型心肾综合征模型，探讨Ⅳ型心肾综合征的病理生理机制。同时采用乳鼠原代心肌细胞和成纤维细胞模型，研究尿毒素硫酸吲哚酚引起的心肌损伤的潜在分子机制。超声心动图检测发现5/6肾切除合并左冠脉前降支结扎组左室射血分数（42.7±3.5%）较5/6肾切除组（74.3±2.7%）显著下降（ p <0.001）。肾功能检测发现，5/6 肾切除合并左冠脉前降支结扎组肾小球滤过率（0.4±0.3 ml/min/kg）较左冠脉前降支结扎组（8.1±0.5 ml/min/kg）显著下降（ p <0.001）， 硫酸吲哚酚血清含量显著增加（66.19±13.17 vs 10.21±1.02 μmol/L, p <0.01）。组织病理检测发现心功能下降伴随有左心室重构。心肌肥大标志基因、促纤维化基因表达增加，细胞凋亡信号调节激酶通路活化等。硫酸吲哚酚经有机阴离子转运蛋白1和3介导进入心肌细胞后，经丝裂原活化蛋白激酶级联调节，引起心肌肥厚和间质纤维化。细胞凋亡信号调节激酶1抑制剂通过抑制硫酸吲哚酚对心肌细胞的毒性，缓解心室重构。研究结果揭示心、肾相互作用的潜在靶点，发现细胞凋亡信号调节激酶1的激活在硫酸吲哚酚引起的心室重构病理过程中起关键作用，为尿毒素心肌病的防治提供研究新思路。申请人以第一作者于J Cell Mol Med发表JCR 2区论文1篇。与同行报道的单手术模型不同，本研究采用双手术模型，研究了肾衰竭基础病理状态下，发生心肌梗死后，心、肾在功能、结构、分子水平上的改变。此外，申请人针对不同心肾综合征模型，阐述了心肾相互作用的分子机制，以唯一作者于Am J Physiol-Renal Physiol发表JCR 2区综述1篇；针对硫酸吲哚酚在心血管疾病进展中的作用，以通信作者于Life Sci发表JCR 3区综述1篇。