GDF11对高糖状态下血管内皮细胞保护作用及机制研究

Hyperglycemia damages vascular endothelium, and plays a key role in the development of diabetic angiopathy. However, the underlying mechanisms are not fully clear. It was reported that growth differentiation factor 11 (GDF11) could reverse age-related cardiac hypertrophy in old mice, improve the function of brain and skeletal muscle in aging mice via Smad2/3 signal pathway, and restore “Rejuvenation function”. However, the data are not available on the protective roles of GDF11 in the damage of endothelium and artery under diabetic conditions. Our preliminary experiments results revealed that GDF11 could attenuate the endothelial cell apoptosis induced by high glucose, up-regulate Bcl-2, and down-regulate Bax expression. Therefore, we hypothized that GDF11 can protect endothelial damage and ameliorate atherosclerosis induced by high glucose. In this programme, ① In vitro study, endothelial cells will be treated with high glucose and GDF11, and the protective effects of GDF11 on endothelial cell apoptosis will be detected. ② In vivo study, apolipoprotein E-null diabetic mice will be treated with GDF11 and an adeno-associated virus vector, and the protective roles of GDF11 on endothelium and artery will be investigated. ③ In both in vitro and in vivo studies, Smad2/2 signal and Akt/eNOS signal pathways will be detected using gene silencing, some inhibitors, western blot as well as other techniques to test whether or not these signal pathways are involved in the protective roles of GDF11 on endothelial dysfunction induced by high glucose. Through these works, we aim of reveal the new mechanisms of diabetic angiopathy, which would provide a new therapeutic target and a new drug for the treatment of diabetic vascular complications.

高糖损伤血管内皮，在糖尿病（DM）血管病变的发生发展中起重要作用，但其机制还未完全阐明。文献报道，生长分化因子11(GDF11)通过Smad2/3通路，改善老年鼠心肌肥厚、大脑和骨骼肌功能，具有“返老还童”作用。但GDF11能否逆转DM引起的内皮和动脉损伤尚未见报道。申请者的预实验显示，GDF11具有抗高糖诱导的内皮细胞凋亡作用，使Bcl-2表达增加，Bax表达降低。据此，申请者提出如下假说：GDF11对高糖状态下血管内皮及动脉具有保护作用。本项目拟探讨：①体外实验探讨GDF11对高糖状态下内皮细胞凋亡的保护作用；②体内试验采用重组GDF11和腺相关病毒等方法探讨GDF11对血管内皮及动脉的保护作用；③采用基因沉默、免疫印迹等方法从体外和体内试验探讨Smad2/3和Akt/eNOS通路是否介导GDF11的内皮保护作用。旨在探讨DM血管病变发病新机制，为防治DM血管病变提供新靶点及新药物。

2型糖尿病是一种年龄相关性疾病，高糖损伤血管内皮，在糖尿病(DM)血管病变的发生发展中起重要作用，但其机制还未完全阐明。文献报道，生长分化因子11(GDF11) 改善多种器官衰老表型，具有“返老还童”作用。但GDF11能否逆转DM引起的内皮和动脉损伤尚未见报道。该项目计划从体外细胞学和在体动物实验2个层面，系统探讨GDF11对DM状态下血管内皮损伤的保护作用及机制。该项目进展顺利，证实了GDF11通过激活TGF-β/Smad和AMPK/eNOS信号转导途径发挥抗动脉粥样硬化的作用。鉴于GDF11对机体多组织器官均发挥重要作用，在较好完成项目基本任务前提下，我们进一步探讨了GDF11对DM小鼠胰岛β细胞功能及数量的影响和GDF11对DM大鼠缺血下肢血管新生的影响。此外，我们将思路转向内分泌领域的研究热点-DPP-4抑制剂，探讨DPP-4抑制剂Alogliptin对高脂饮食小鼠的寿命和生活质量的影响及其作用机制，为提高肥胖和超重个体的生活质量并延长其寿命提供潜在的治疗策略及理论依据。.在GDF11相关研究中：1.抗动脉粥样硬化方面，GDF11可改善内皮依赖性舒张功能障碍，减少血管内皮细胞凋亡，减小动脉粥样硬化斑块表面积及横断面积, 促进内皮细胞增殖，其保护作用与激活TGF-β/Smad和AMPK/eNOS信号途径有关。2.对胰岛β细胞的影响方面，GDF11可能通过激活TGF-β/Smad2及PI3K/AKT/FoxO1信号通路改善DM小鼠糖脂代谢，抑制胰高血糖素的释放，保护胰岛β细胞功能，减少β细胞凋亡；使用抗体中和血液中GDF11可诱导相反作用。3.在缺血下肢血管新生的影响方面，GDF11可能通过激活TGF/Smad2/3及AKT/HIF1信号通路改善内皮祖细胞(EPCs)功能，促进DM大鼠下肢缺血恢复；使用抗体中和循环中GDF11可引起相反作用。.在Alogliptin相关研究中，Alogliptin干预可以延长高脂饮食小鼠的寿命并提高其生活质量，激活自噬可能是Alogliptin干预发挥有益作用的内在机制。.上述结果提示，GDF11可延缓动脉粥样硬化的发生与发展，在防治动脉粥样硬化方面具有良好的临床应用前景；此外，GDF11可能在胰岛β细胞功能及含量中扮演重要角色，并且可能通过改善EPCs功能促进DM下肢缺血恢复，为探讨DM及血管并发症的防治方法提供了新的思路。