CD38/NAADP信号调控自噬参与糖尿病性冠状动脉粥样硬化的机制研究

Diabetic atherosclerosis is a common vascular complication of diabetes. However, the mechanisms underlying the diabetic atherosclerosis are still unclear. CD38 is a multifunctional enzyme responsible for the production and metabolism of nicotinic acid adenine dinucleotide phosphate (NAADP), a new potent Ca2+ mobilizer in lysosomes. Primary mouse coronary arterial myocytes (CAMs) from wild-type and CD38 gene knockout mice are treated with high glucose or advanced glycation end products (AGEs). It is investigated that CD38/NAADP signal pathway regulates autolysosome formation and activity, which is responsible for the degradation of sequestosome1 (SQSTM1/p62), a selective substrate for autophagy. Further study is performed that p62 plays a critical role on the dedifferentiation and proliferation in CAMs. Next, the mouse model of type 2 diabetic atherosclerosis is established with streptozotocin (STZ) and high-fat diet to detect the role of CD38/NAADP signal pathway in pathological process and vascular function. Lastly, based on the upstream mechanisms of CD38/NAADP signal pathway, L-2-oxothiazolidine-4-carboxylic acid (OTC) and other potential anti-diabetic agents are used to test their therapeutic role on coronary atherosclerosis in diabetes. Our study reveals new mechanisms of coronary dysfunction in diabetes, which is of great theatrical and practical significance to improve diabetic vascular complications.

糖尿病性动脉粥样硬化是糖尿病常见的大血管并发症，发病机制极其复杂，尚未完全阐明。白细胞分化抗原38(CD38)催化NAADP的合成和降解，NAADP是一种新的诱导溶酶体Ca2+释放的第二信使。本项目利用CD38基因敲除的小鼠冠状动脉平滑肌细胞，建立高糖或者糖基化终末产物诱导细胞损伤的模型，分析CD38/NAADP信号通路调控自噬溶酶体形成和活性，进而影响p62蛋白水平，参与血管平滑肌细胞分化和增殖的机制。同时，利用高脂饲料联合STZ诱导的2型糖尿病性冠状动脉粥样硬化模型，研究CD38/NAADP信号参与小鼠冠状动脉血管平滑肌病理改变和功能损伤。最后，基于CD38/NAADP信号上游调控机制的研究，评估CD38激活剂丙半胱氨酸和其他潜在抗糖尿病药物对糖尿病性冠状动脉粥样硬化的改善作用。本项目揭示糖尿病性冠状动脉功能失调的新机理，对靶向性改善糖尿病血管并发症具有重要理论意义和应用价值。

冠状动脉粥样硬化是冠心病的最常见的原因，2型糖尿病性冠状动脉粥样硬化的发生率几乎是非糖尿病人群的4倍，而且病变进展快，危害比非糖尿病患者冠状动脉粥样硬化严重,防治冠状动脉粥样硬化有赖于对发病机制的深入了解。血管平滑肌细胞（VSMCs）是动脉粥样硬化斑块主要的细胞成分，也是粥样硬化斑块形成的主要启动子。人类冠状动脉的组织学研究提示易于发生粥样硬化病变的区域含有较多VSMCs，而不易发生的部位VSMCs较少。糖尿病的高血糖、胰岛素抵抗、脂类代谢紊乱和慢性炎症状态均可促使VSMCs从收缩型转化为合成型，从而获得增殖和迁移的能力，而VSMCs增殖和迁移是动脉粥样硬化病变形成和发展的关键环节，但血管平滑肌细胞损伤的明确机制尚未完全阐明。本研究发现高糖抑制血管平滑肌细胞自噬，而依赖AKT/mTOR调控的自噬介导高糖诱导的血管平滑肌细胞表型转化，参与了糖尿病导致的血管收缩功能障碍。另外，Syk/NLRP3炎性小体和Nox4/AMPK信号通路分别调控糖尿病血管内膜增生，参与糖尿病诱导的颈动脉血管狭窄。白细胞分化抗原38(Cluster of differentiation 38, CD38)通过NLRP3炎性小体调控高糖诱导VSMCs重构，这与cADPR/Ca2+诱导的VSMCs线粒体损伤有关。基于以上机制，我们发现前列地尔，尼克酰胺，成纤维细胞生长因子21（FGF21），二甲双胍/利格列汀均可以改善糖尿病诱导的VSMCs损伤。同时我们在VSMCs功能密切相关的血管内皮细胞，血管成纤维细胞，血管内皮祖细胞开展了相关的研究。本项目发现多项调控糖尿病诱导血管平滑肌细胞损伤的机制，揭示了糖尿病性动脉功能失调的新机理，这对靶向性改善糖尿病血管并发症，开发有效治疗药物具有重要理论意义和应用价值。