冠状动脉微血管内皮细胞释放的神经调节蛋白-1对缺血/再灌注心肌的作用及其机制探讨

Role of neuregulin-1 released from cardiac microvascular endothelial cells in ischemia/reperfusion myocardium and its mechanism of action

目的探讨大鼠缺血/再灌注损伤(I/RI)时,神经调节蛋白-1(NRG-1)在冠状动脉微血管内皮细胞(CMECs)-心肌细胞共培养中的作用及其机制。方法分离培养大鼠CMECs和心肌细胞,建立CMECs-心肌细胞共培养(Coculture)模型和体外模拟缺血/再灌注(SI/R)模型,收集CMECs培养上清。MTT法检测心肌细胞活性,TUNEL法检测心肌细胞凋亡指数,Western blot法检测CMECs培养上清中NRG-1表达、心肌细胞p Erb B2、p ERK基因和环氧化酶-2(COX-2)水平,含半胱氨酸的天冬氨酸蛋白水解酶-3(caspase-3)酶活性反应心肌细胞凋亡。结果在心肌细胞中,与对照组相比,SI/R(4 h/4 h)组细胞活性明显降低(P<0.01),SI/R+Coculture组细胞活性升高(P=0.02)。CMECs在SI/R 4 h/4 h时,NRG-1的分泌较对照组增加最明显(P<0.01)。心肌细胞SI/R组凋亡指数和Caspase-3酶活性比对照组明显升高(27.97±0.90比3.58±0.23,P<0.01;375.93±11.76比100.00±0.00,P<0.01)。共培养或NRG-1处理细胞后,凋亡指数和Caspase-3酶活性较SI/R组降低(16.82±1.03比27.97±0.90,P<0.01;166.16±15.15比375.93±11.76,P<0.01),且Erb B2和ERK磷酸化水平以及COX-2表达明显增加(均为P<0.01)。用Erb B2或ERK1/2抑制剂预处理心肌细胞后,共培养和NRG-1的作用消失(均为P<0.01)。结论在I/RI过程中,CMECs释放NRG-1,抑制I/RI诱导的心肌细胞凋亡,其保护作用与增加Erb B2、ERK磷酸化和COX-2表达可能有关。

Objective To explore the effects and mechanism of neuregulin-1（ NRG-1） in rat cardiac microvascular endothelial cells（ CMECs）-cardiomyocytes coculture,during ischemia / reperfusion injury. Methods Cardiac myocytes were isolated from the hearts of neonatal rats and CMECs from the adult rats. CMECs-cardiomyocytes coculture model was established. Then cells were endured simulated I / R（ 4 h/4 h）. Collected CMECs culture medium during SI/R. The cell viability of cardiomyocytes was measured by MTT assay. The apoptosis of cardiomyocytes was detected by TUNEL method. The expression of secreted NRG-1 in CMECs culture medium,phosphorylation of Erb B2 and ERK and COX-2 in cardiac myocytes were analyzed by Western blot. Measured Caspase-3 activity reflected the apoptosis of cardiomyocytes. Results The cardiomyocytes viability was impaired in the SI / R（ 4 h /4 h） group（ P〈0. 01）while increased in the SI / R ＋ Coculture group（ P = 0. 02）. Within the groups of CMECs,the secretion ofNRG-1 was remarkable increased in the time of 4 h /4 h under SI / R（ P〈0. 01） when compared with the Control group. Within the groups of cardiomyocytes,the apoptosis index and Caspase-3 activity were increased after SI / R when compared with the Control group（ 27. 97 ± 0. 90 vs. 3. 58 ± 0. 23,P〈0. 01; 375. 93 ± 11. 76 vs. 100. 00 ± 0. 00,P〈0. 01）. While trained with Coculture or NRG-1 during SI / R could reduce the apoptosis index and Caspase-3 activity when compared with the SI / R group（ 16. 82 ± 1. 03 vs. 27. 97 ± 0. 90,P〈0. 01; 166. 16 ± 15. 15 vs. 375. 93 ± 11. 76,P〈0. 01）. Besides,they can significant up-regulate the level of phosphorylation of ErbB 2 and ERK and the expression of COX-2（ P〈0. 01 vs. Control and SI / R）. However,when cardiomyocytes were pretreated with ErbB 2 or ERK1 /2 inhibitor,the effect of Coculture and NRG-1vanished（ P〈0. 01）. Conclusions The process of I / RI,the secretion of NRG-1in CMECs protect cardiomyocytes against ischemic reperfusion injury through up-regulation of pE rbB 2,pE RK and COX-2.