纳米二氧化硅颗粒调控线粒体SIRT3/ROS/CaMKⅡ致心律失常作用及机制研究

Atmospheric particulate matter is closely related to cardiovascular disease. Silica nanoparticle is one of the inert nuclei of atmospheric particulate matter. Our previous research found that silica nanoparticles did damage on the mitochondria of myocardium, inhibited the activity of SIRT3, reduced myocardial contractility and heart rate. In this study, Wistar rats and myocardial cells differentiated from human induced pluripotent stem cells, hIPSCs, were used to investigate the effects of silica nanoparticles on the occurrence and development of arrhythmia, and its related mechanisms. The in vivo rat model with low-dose silica nanoparticles exposure was performed, and the cardiac structure, function, electrocardiogram, oxidative stress, mitochondrial membrane potential, energy metabolism, ATP content, NAD+/NADH ratio, SIRT3, CaMK II, calcium content and calcium channel proteins were all determined to explore the induction of arrhythmia by silica nanoparticles from the perspective of "mitochondrial SIRT3-ROS-CaMKⅡ-calcium overload-electrophysiological conduction abnormality". In the mechanism study, the hIPSCs-differentiated myocardial cells as cell model, and the antioxidant N-acetylcysteine, SIRT3 over-expression and CaMK II-specific inhibitor, KN-93, were used to validate the regulatory role of SIRT3-ROS-CaMKⅡ in cardiac arrhythmias induced by silica nanoparticles. The research would provide evidence for early prevention and control of cardiovascular disease and the development of standards for atmospheric particulate matter.

大气颗粒物与心血管疾病密切相关。纳米SiO2是大气颗粒物惰性核之一，课题组前期发现其损伤心肌线粒体，抑制SIRT3活性，导致心肌收缩力减弱、心率降低。本研究拟采用Wistar大鼠和人诱导性多能干细胞（hIPSCs）分化的心肌细胞研究纳米SiO2颗粒在心律失常发生发展中的作用及机理。体内实验建立纳米SiO2低剂量染毒大鼠模型，检测心脏结构、功能、心电图、氧化应激、线粒体膜电位、能量代谢、ATP、NAD+/NADH、SIRT3、CaMKⅡ、钙和钙通道蛋白，从“线粒体SIRT3-ROS-CaMKⅡ-钙超载-电生理传导异常”角度探讨纳米SiO2致心律失常作用。机制研究采用抗氧化剂N-乙酰半胱氨酸、SIRT3过表达和CaMKⅡ特异抑制剂KN-93，利用hIPSCs分化的心肌细胞，验证SIRT3/ROS/CaMKⅡ在纳米SiO2致心律失常中的调控作用，为心血管疾病早期防治和大气颗粒物标准制订提供依据。

纳米二氧化硅（silica dioxide，SiO2）是我国乃至世界上工业化大规模生产产量最高的一种纳米材料，随着其全球产量和应用范围的逐渐增大，最终将不可避免的进入生态圈及大气环境中。纳米SiO2也广泛存在于煤、石油等矿物质燃烧产物中，是大气超细颗粒的重要组分之一。因此，加强纳米SiO2颗粒有害生物效应研究是保护环境和保障公众健康的重大需求。课题组在前期研究基础上，首先采用体内实验建立纳米SiO2多次染毒动物模型，并利用体外细胞模型（人诱导性多能干细胞hIPSCs分化的心肌细胞、人心肌细胞株AC16）进行体内实验现象的验证及其调控作用机制探讨。体内研究证实，纳米SiO2暴露可造成心肌损伤、心脏收缩功能降低甚至心室重构，且存在剂量效应；体外研究显示，纳米SiO2染毒导致心肌细胞收缩力减弱、心脏跳动频率异常，造成心肌细胞凋亡。线粒体是纳米SiO2发挥心肌细胞毒性的重要靶点，ROS/Ca2+/CaMKⅡ信号通路的激活可能是纳米SiO2致心肌损伤、收缩障碍和心率紊乱的重要调控作用机制。此外，颗粒粒径是影响纳米SiO2心肌毒性的重要因素。本项目研究结果对于纳米SiO2安全性评价、标准制订提供实验依据，对于保护环境、促进公众健康及加强纳米安全具有重要意义。目前项目已发表SCI论文7篇，中文核心期刊2篇，参加国内学术交流6次，做分会场报告1次，发表会议论文1篇。