运动对内皮祖细胞微囊泡中miR-126的调节作用及在减轻糖尿病心血管损伤中的意义

Increasing evidence suggests that aerobic exercise can improve vascular function and reduce the risk of cardiovascular events in diabetic patients, though the molecule mechanism remains unclear. Endothelial progenitors (EPCs) could promote endothelial angiogenesis, which is important in promoting endothelial repair and ameliorating vascular function. Cellular microvesicles (MVs) participate in intercellular communication by delivering microRNAs (miRs) and proteins to target cells. Recently, we have shown that the miR-126 level was significantly decreased in circulating EPCs, and the number of EPC-MVs was increased in diabetic patients. EPC-MVs of diabetic patients decreased the level of miR-126 and exhibited detrimental effects on the function of EPCs. It is reported that exercise can increase the level of circulating miR-126. However, whether exercise could modulate miR-126expression in EPC-MVs and whether EPC-MVs-miR-126 could target SPRED1 and TRAF7 to protect ECs and cardiomyocytes against diabetic injury remain unknown. In this proposal, we will determine the role of miR-126 in EPC-MVs in protecting ECs and cardiomyocytes against high glucose-induced injury, and will investigate the correlation of exercise intensity and the level of miR-126 in EPC-MVs. The results will provide theory basis and parameters of optimal exercise intensity for cardiovascular protection in patients with diabetes.

有氧运动能改善心血管的功能和降低糖尿病心血管事件的风险，但其机制不明。内皮祖细胞（EPCs）能促进内皮细胞（ECs）功能和再生，是减轻心血管损伤的重要机制之一。微囊泡（MVs）能在细胞间传递miRNA（miR）等信息。前期实验发现糖尿病人循环EPCs中miR-126水平降低，但EPC-MVs数量增加，与正常EPCs共培养可损伤其功能。另据报道，有氧运动可提高循环miR-126水平，然而，是否可通过EPC-MVs中miR-126及下游靶基因SPRED1和TRAF7改善糖尿病的心血管功能并不清楚。本课题在高糖损伤的模型上通过增加和减少miR-126在EPC-MVs中的水平明确其对ECs和心肌细胞的保护作用和机制，并在糖尿病小鼠模型上探讨运动强度对心血管的效应与EPCs-MVs中miR-126水平的相关性，为糖尿病患者寻找合适的运动强度和评价指标提供理论依据。

糖尿病（T2DM）作为以慢性高血糖和胰岛素抵抗为特征的代谢性疾病，是心血管疾病的重要危险因素，约68%的T2DM患者会死于心血管并发症。内皮祖细胞(EPCs)是减轻心血管损伤的重要机制之一。MicroRNA-126（miR-126）作为一种血管生成调节因子，可通过微囊泡（MVs)和外泌体(EXs）进行细胞间的信号传递降低心血管损伤。适当的运动是预防和治疗T2DM心血管并发症的首要策略。在本项目中，我们通过细胞实验和动物实验探讨了不同强度运动对糖尿病心血管的保护效应和机制，发现：1)在体外高糖环境可刺激EPC-MVs释放，但其内含物miR-126水平显著下降；2)体外实验通过miR-126的抑制剂和模拟物的干预明确了EPCs-MVs-miR-126对高糖导致ECs损伤的保护作用，包括促进小管生成、EC迁移和减少EC凋亡；3)通过对糖尿病小鼠心功能，心肌和主动脉的电镜、HE染色、DHE染色、WGA-AF488染色和α-SMA染色等检测，表明8周中等强度运动干预比小强度和高强度运动在心功能、减少心肌ROS生成和增加血管生成上有更好的保护效应；4)有氧运动干预可有效改善糖尿病小鼠血糖和胰岛素水平，提高循环EPCs，EPC-MVs及miR-126的水平；5)中等强度运动组糖尿病小鼠的循环EPC-EX与EC共培养，发现通过上调miR-126通路降低高糖导致的EC凋亡，改善EC的血管生成功能；6)中等强度运动组的循环EPC数量与循环、主动脉miR-126有显著相关性；7)中等强度运动是通过促进心肌和心血管的miR-126/SPRED1和miR-126/VCAM-1通路促血管生成、miR-126/NF-κB通路抗炎和miR-126/TRAF7/caspase-3抗凋亡作用来保护心血管功能。综上所述，循环EPC-MVs-miR-126可成为有氧运动治疗糖尿病患者心血管病变的评估指标。这些结果对糖尿病心血管病变的防治和预后具有重要的理论意义和临床价值。