Tao Liu1, You Zhou2, Jiang-You Wang3, Qiang Su1, Zhong-Li Tang1, Yang-Chun Liu1, Lang Li4. 1. Department of Cardiology, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China. 2. Department of Cardiology, Minzu Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China. 3. Department of Cardiology, Wuhan Asia Heart Hospital, Wuhan, Hubei, China. 4. Department of Cardiology, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China drlilang@163.com.
Abstract
BACKGROUND: Cardiomyocyte apoptosis by coronary microembolization (CME) contributes to myocardial dysfunction, in which mitochondrial pathway and death receptor pathway are activated. Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) is a membrane protein involved in apoptosis. The study aimed to explore the role of LOX-1 in the activation of these 2 major apoptotic pathways. METHODS: Twenty Bama miniature swine were randomized into 4 groups (n = 5 per group). The groups were Sham, CME, LOX-1 small-interfering RNA (siRNA), and control siRNA. Microspheres were injected into the left anterior descending artery of swine to establish CME model. Twelve hours after operation, cardiac function, serum c-troponin I level, microinfarct, and apoptotic index were examined. The levels of LOX-1, Bcl-2, Bax, cytochrome c as well as cleaved caspase 9, -8, and -3 were detected. RESULTS: Myocardial dysfunction, enhanced serum c-troponin I, microinfarct, and apoptosis were induced following CME. Moreover, CME induced increased expression of LOX-1, Bax, cytochrome c, cleaved caspase 9, -8, and -3 as well as decreased Bcl-2 expression levels. The LOX-1 siRNA reversed these effects by CME except cleaved caspase 8 expression, while the control siRNA had no effect. CONCLUSION: Coronary microembolization induces cardiomyocyte apoptosis via the LOX-1-dependent mitochondrial pathway and caspase 8-dependent pathway.
BACKGROUND: Cardiomyocyte apoptosis by coronary microembolization (CME) contributes to myocardial dysfunction, in which mitochondrial pathway and death receptor pathway are activated. Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) is a membrane protein involved in apoptosis. The study aimed to explore the role of LOX-1 in the activation of these 2 major apoptotic pathways. METHODS: Twenty Bama miniature swine were randomized into 4 groups (n = 5 per group). The groups were Sham, CME, LOX-1 small-interfering RNA (siRNA), and control siRNA. Microspheres were injected into the left anterior descending artery of swine to establish CME model. Twelve hours after operation, cardiac function, serum c-troponin I level, microinfarct, and apoptotic index were examined. The levels of LOX-1, Bcl-2, Bax, cytochrome c as well as cleaved caspase 9, -8, and -3 were detected. RESULTS:Myocardial dysfunction, enhanced serum c-troponin I, microinfarct, and apoptosis were induced following CME. Moreover, CME induced increased expression of LOX-1, Bax, cytochrome c, cleaved caspase 9, -8, and -3 as well as decreased Bcl-2 expression levels. The LOX-1 siRNA reversed these effects by CME except cleaved caspase 8 expression, while the control siRNA had no effect. CONCLUSION: Coronary microembolization induces cardiomyocyte apoptosis via the LOX-1-dependent mitochondrial pathway and caspase 8-dependent pathway.