Li Xinyuan, Fang Pu, Li Yafeng, Kuo Yin-Ming, Andrews Andrew J, Nanayakkara Gayani, Johnson Candice, Fu Hangfei, Shan Huimin, Du Fuyong, Hoffman Nicholas E, Yu Daohai, Eguchi Satoru, Madesh Muniswamy, Koch Walter J, Sun Jianxin, Jiang Xiaohua, Wang Hong, Yang Xiaofeng
From the Centers for Metabolic Disease Research, Cardiovascular Research, Thrombosis Research (X.L., P.F., Y.L., G.N., C.J., H.F., H.S., F.D., S.E., X.J., H.W., X.Y.), Department of Pharmacology (X.L., P.F., Y.L., G.N., C.J., H.F., H.S., F.D., W.J.K., X.J., H.W., X.Y.), Department of Biochemistry (N.E.H., M.M.), Department of Physiology (S.E.), Center for Translational Medicine (N.E.H., M.M., W.J.K.), and Department of Clinical Sciences (D.Y.), Temple University School of Medicine, Philadelphia, PA; Department of Cancer Biology, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA (Y.-M.K., A.J.A.); and Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA (J.S.).
Arterioscler Thromb Vasc Biol. 2016 Jun;36(6):1090-100. doi: 10.1161/ATVBAHA.115.306964. Epub 2016 Apr 28.
Hyperlipidemia-induced endothelial cell (EC) activation is considered as an initial event responsible for monocyte recruitment in atherogenesis. However, it remains poorly defined what is the mechanism underlying hyperlipidemia-induced EC activation. Here, we tested a novel hypothesis that mitochondrial reactive oxygen species (mtROS) serve as signaling mediators for EC activation in early atherosclerosis.
Metabolomics and transcriptomics analyses revealed that several lysophosphatidylcholine (LPC) species, such as 16:0, 18:0, and 18:1, and their processing enzymes, including Pla2g7 and Pla2g4c, were significantly induced in the aortas of apolipoprotein E knockout mice during early atherosclerosis. Using electron spin resonance and flow cytometry, we found that LPC 16:0, 18:0, and 18:1 induced mtROS in primary human aortic ECs, independently of the activities of nicotinamide adenine dinucleotide phosphate oxidase. Mechanistically, using confocal microscopy and Seahorse XF mitochondrial analyzer, we showed that LPC induced mtROS via unique calcium entry-mediated increase of proton leak and mitochondrial O2 reduction. In addition, we found that mtROS contributed to LPC-induced EC activation by regulating nuclear binding of activator protein-1 and inducing intercellular adhesion molecule-1 gene expression in vitro. Furthermore, we showed that mtROS inhibitor MitoTEMPO suppressed EC activation and aortic monocyte recruitment in apolipoprotein E knockout mice using intravital microscopy and flow cytometry methods.
ATP synthesis-uncoupled, but proton leak-coupled, mtROS increase mediates LPC-induced EC activation during early atherosclerosis. These results indicate that mitochondrial antioxidants are promising therapies for vascular inflammation and cardiovascular diseases.
高脂血症诱导的内皮细胞（EC）激活被认为是动脉粥样硬化发生过程中单核细胞募集的起始事件。然而，高脂血症诱导EC激活的潜在机制仍不清楚。在此，我们验证了一个新的假说，即线粒体活性氧（mtROS）作为早期动脉粥样硬化中EC激活的信号介质。
代谢组学和转录组学分析显示，在早期动脉粥样硬化期间，载脂蛋白E基因敲除小鼠的主动脉中，几种溶血磷脂酰胆碱（LPC）种类，如16:0、18:0和18:1，以及它们的加工酶，包括Pla2g7和Pla2g4c，均显著上调。通过电子自旋共振和流式细胞术，我们发现LPC 16:0、18:0和18:1在原代人主动脉EC中诱导mtROS产生，且不依赖于烟酰胺腺嘌呤二核苷酸磷酸氧化酶的活性。机制上，利用共聚焦显微镜和海马XF线粒体分析仪，我们发现LPC通过独特的钙内流介导的质子泄漏增加和线粒体氧还原诱导mtROS产生。此外，我们发现mtROS通过调节激活蛋白-1的核结合并在体外诱导细胞间黏附分子-1基因表达，从而促进LPC诱导的EC激活。此外，我们利用活体显微镜和流式细胞术方法表明，mtROS抑制剂MitoTEMPO可抑制载脂蛋白E基因敲除小鼠的EC激活和主动脉单核细胞募集。
ATP合成解偶联但质子泄漏偶联的mtROS增加介导了早期动脉粥样硬化中LPC诱导的EC激活。这些结果表明，线粒体抗氧化剂有望用于治疗血管炎症和心血管疾病。
