AMPK在糖尿病抑制腹主动脉瘤形成中的作用及转化医学研究

Diabetes is one of high risk factors in cardiovascular diseases. However, overwhelming data from epidemiological studies and experimental investigations reveal that diabetes is a negative risk factor for abdominal aortic aneurysm (AAA). The cellular and molecular mechanisms by which diabetes delays AAA formation remain poorly understood. AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase involved in the regulation of cellular and organismal metabolism. Deficiency of AMPK in Apoe-/- mice ablated AngII-induced AAA formation. Our exciting preliminary data have revealed that high glucose (or hyperglycemia) suppressed AMPK activity in cultured cells, vascular tissues from animal or human. Administration of metformin significantly aggravated AngII-induced AAA formation. Based on these observations, we propose that inhibition of AMPK by high glucose delays the formation of AAA. In order to test the hypothesis, comprehensive experimental approaches including pharmacological and genetic means will be used (1) to investigate the molecular and cellular mechanisms by which high glucose inactivates AMPK, (2) to determine the essential role of AMPK in diabetes-delayed AAA formation, and (3) to establish the relationship among diabetes, AMPK and AAA in clinical patients. This study will yield important insights to understand how diabetes delays AAA formation, identify the novel biomarker to evaluate the risk of AAA in early stage, and provide a promising approach to the prevention and treatment of AAA.

高血糖作为公认的心血管疾病危险因素，但流行病学证据显示糖尿病与腹主动脉瘤（AAA）的发病呈负相关，其分子机制不明。既往研究发现敲除AMP活化的蛋白激酶（AMPK）基因在Apoe-/-小鼠抑制了血管紧张素II（AngII）所诱导的AAA 形成。本次预实验发现高血糖能抑制血管组织AMPK的活性和延缓AngII所致的AAA形成；反之，激活AMPK则促进了AngII的致AAA作用。据此，我们假设"高血糖通过抑制AMPK而延缓AAA的形成"。本课题拟运用细胞与分子生物学、生物化学、药理学、基因芯片、生物信息学和临床调查等研究手段，体外、体内和临床研究相结合，在分子和细胞水平研究高血糖抑制AMPK的机制，在动物水平研究AMPK在糖尿病延缓AAA形成中的作用，在临床水平确立AMPK与AAA的相关性。本研究将基础研究成果用于解决临床问题，旨在阐明糖尿病抑制AAA形成的分子机制，为临床防治AAA提供新思路。

糖尿病作为大多数心血管疾病的高危因子，但流行病学和实验证据却提示糖尿病与腹主动脉瘤（AAA）的发病呈明显的负相关，其相关机制不明。本课题发现糖尿病高血糖状态下，AMPK的活性显著降低，血管壁胶原沉积减少，弹力纤维断裂，显著促进了AngII所诱导的Apoe-/-小鼠的死亡率和AAA的形成率。在培养的VSMC，高糖促进了AMPKα-M200蛋氨酸的氧化修饰和AMPKβ-C225半胱氨酸的亚硝基化修饰，抑制AMPK的活性，再经AP-2α/miRNA-124/P4Hα1信号通路抑制胶原成熟。普伐他汀通过ROS激活AMPK，再激活AP-2α，显著增加了MMP2的表达和活性，导致弹力纤维断。普伐他汀经AMPK激活AP-2α/MMP2信号通路，进而促进AngII所诱导的Apoe-/-小鼠AAA的形成。沉默AMPK或AP-2α显著抑制了他汀的促AAA作用。阿司匹林和他汀类似，显著抑制了AngII所诱导的Apoe-/-小鼠AAA的形成。服用普伐他汀患者及AAA患者AMPK或者AP-2α的活性上调，而糖尿病患者AMPK活性显著降低。AAA是人体的一枚定时炸弹，其瘤体破裂是临床上心血管患者死亡的主要因素。如何预防AAA的形成是当前心血管学术界急需解决的问题。通过本课题的研究发现，二甲双胍、他汀、阿司匹林等药物能激活AMPK，具有促进AAA形成或破裂的作用，在AAA患者应谨慎使用。