应用OCT探寻硫化氢调控高糖高脂状态下平滑肌细胞表型转换的机制研究

Diabetic cardiovascular complications are the leading causes of death in diabetes. Glucose-lipid metabolism dysfunction caused by diabetes is an important factor in the incidence of atherosclerosis (AS). Studies have shown that AMPKα2 regulates vascular smooth muscle (VSMCs) from contractile to synthetic phenotype, and participate in the formation of AS plaques. Our previous research have revealed that administration of H2S reduce diabetes-induced cellular apoptosis in cardiomyocytes, smooth muscle cells and endothelial cells ,along with the occurrence of autophagy. Our team also confirm that the stability of vulnerable plaques using optical coherence tomography (OCT) correlates with blood glucose, lipid levels, and serum H2S levels in AS patients. Meanwhile , H2S treatment decrease reactive oxygen species (ROS) in VSMCs and up-regulates the expression of AMPKα2 in hyperglycemia and hyperlipidemia-induced mice, which has not been reported. We set up a hypothesis that 'Increasing the level of H2S in VSMCs might activate AMPKα2 and inhibit the proliferation of VSMCs'. The present project will combine using OCT and molecular biology technology to reveal the mechanism of H2S mediated hyperglycemia and hyperlipidemia-induced VSMCs phonotypic switching. It is reasonable to speculate that our project will bring new dawning for stabilizing vulnerable plaque and preventing the process of diabetic atherosclerosis.

糖尿病诱发的心血管疾病死亡是糖尿病患者首要死亡原因。糖尿病引起的糖脂代谢异常是造成糖尿病动脉粥样硬化（AS）发生率较高的重要因素。研究表明AMPKα2可以调控血管平滑肌（VSMCs）由收缩型向合成型转换，参与AS斑块的形成。我们前期的研究发现，给予H2S处理能降低糖尿病诱导心肌细胞、平滑肌细胞、内皮细胞的凋亡，并发现自噬现象的产生。应用光学相干断层成像（OCT）发现易损斑块稳定性与AS患者血清H2S水平具有相关性，同时H2S能够降低高糖高脂小鼠模型中VSMCs活性氧水平，增加AMPKα2表达。因此我们推测“增加VSMCs中H2S含量可以激活AMPKα2抑制VSMCs增殖”。本项目将联合OCT从组织、细胞和分子信号水平多维度揭示H2S调控高糖高脂状态下VSMCs表型转换机制，此研究将为延缓糖尿病AS进展，增加斑块稳定性提供新的理论依据和潜在治疗靶点。

高糖培养（HG）刺激诱导血管平滑肌细胞（VSMCs）的细胞表型转换；然而，对VSMC表型转换的调节仍知之甚少。在这里，我们表明HG刺激激活AMP激活激酶（AMPK），这反过来限制了HG状态下VSMCs中的蛋白质合成。培养的VSMC暴露于HG下或外源性羟基过氧化氢（TBHP）引起时间和剂量依赖性AMPK激活，表现为AMPK-Thr172和乙酰辅酶A羧化酶-Ser79（AMPK的下游酶）的磷酸化增加。而H2S显著减弱HG诱导的AMPK激活。VSMCs氧化应激诱导AMPK激活，表明HG激活的AMPK由氧化应激介导。与此一致，VSMCs暴露于高糖或TBHP，外源性给予H2S呈时间和浓度依赖性地恢复了内质网和线粒体的功能。此外，我们进一步评估了其在2型糖尿病动物模型中激活主动脉AMPK的潜力，并发现腹腔注射12周H2S可导致ob/ob或db/db小鼠主动脉AMPK激活。总之，H2S可能通过AMPK激活抑制高糖诱导的VSMC增殖和迁移。