Mechanisms of cardiovascular dysfunction in diabetes

描述(由申请人提供)：糖尿病相关的内皮损伤和血管功能障碍与局部的、自由基相关的过程有关。这种内皮细胞死亡和损伤的药理调节可能为晚期糖尿病血管功能障碍的实验性治疗提供新的途径。在之前的资助期间，我们获得了培养内皮细胞的数据，显示在高血糖期间内皮细胞附近产生的氧化剂触发了由核酶多聚(ADP-核糖)聚合酶(PARP)控制的细胞内级联反应。这会导致PARP的激活，从而启动能量消耗的代谢循环，导致细胞功能障碍。我们的数据还表明，高糖在体外激活内皮细胞中的PARP途径。PARP的药物抑制或遗传失活可减少氧化剂或高糖介导的内皮损伤的发生。链脲佐菌素破坏大鼠的功能性胰岛细胞导致慢性高血糖、血管外氧化剂的产生、内皮细胞内PARP的激活和内皮功能的丧失。在胰岛破坏后开始抑制PARP，维持和恢复了正常的血管反应性，尽管持续存在严重的高血糖。现在，我们建议进行机制研究和其他明确的体内研究，以确定PARP在糖尿病血管衰竭中的作用。我们将建立导致糖尿病患者PARP激活的分子触发因素。此外，我们还将描述内皮损伤的前哨标志物的变化，以及PARP途径的作用。体内研究将得到体外研究的补充，研究高糖诱导的大血管和微血管内皮细胞中PARP的激活和细胞死亡的模式。另一个目的是在慢性大鼠糖尿病模型上进行研究，以描绘PARP在糖尿病相关的视网膜病变、肾病和神经病变发展中的作用。我们还将把研究范围从血管功能障碍扩展到心肌功能障碍(糖尿病心肌病)。本研究的最终目的是研究PARP在人类微血管系统中的激活情况，以及PARP的激活程度与人类内皮功能障碍的程度之间的关系。

DESCRIPTION (provided by applicant): Diabetes-associated endothelial injury and vascular dysfunction is related to local, free radical-related processes. Pharmacological modulation of this endothelial cell death and injury may provide novel avenues for the experimental therapy of the vascular dysfunction in advanced diabetes. In the prior funding period, we obtained data in cultured endothelial cells showing that oxidants produced in the Vicinity of endothelial cells during hyperglycemia trigger an intracellular cascade culminating governed by the nuclear enzyme poly (ADP-ribose) polymerase (PARP). This results in activation of PARP, which initiates an energy consuming metabolic cycle, with resultant cell dysfunction. Our data also show that high glucose activates the PARP pathway in endothelial cells in vitro. Pharmacological inhibition or genetic inactivation of PARP reduces the development of oxidant- or high glucose mediated endothelial injury. Destruction of functional islet cells with streptozotocin in rats induced chronic hyperglycemia, extravascular production of oxidants, activation of PARP in the endothelium, and a loss of endothelial function. PARP inhibition, starting after the time of islet destruction, maintained and restored normal vascular responsiveness, despite the persistence of severe hyperglycemia. Now we propose mechanistic studies and additional, definitive in vivo studies to establish the role of PARP in diabetic vascular failure. We will establish the molecular triggers leading to PARP activation in diabetes. In addition, we will characterize changes in sentinel markers of endothelial injury, and the role of the PARP pathway. The in vivo studies will be complemented by in vitro studies investigating the mode of high glucose induced PARP activation and cell death in macro- and microvascular endothelial cells. A further aim is to perform studies in chronic rat diabetes models to delineate the role of PARP in the development of retinopathy, nephropathy and neuropathy associated with diabetes mellitus. We will also extend the studies from the vascular dysfunction to the myocardial dysfunction (diabetic cardiomyopathy). The final aim of the study is to investigate the activation of PARP in human microvasculature, and to correlate the degree of PARP activation with the degree of endothelial dysfunction in humans.