Ang II, RAGE and Oxidative Stress in Type II Diabetic Coronary Artery Remodeling

2型糖尿病可引起包括冠状动脉疾病在内的心血管并发症。关于糖尿病对冠状动脉结构重塑的影响，我们所知甚少。冠状动脉管腔直径和硬度的改变导致冠状动脉血流储备减少。细胞外基质（ECM）的组成和血管平滑肌细胞（VSMC）的生长都是动脉重塑的关键决定因素。慢性高血糖诱导的晚期糖基化产物（AGEs）的形成和肾素血管紧张素系统（RAS）的激活在2型糖尿病中增加，并与氧化应激增加有关。使用db/db小鼠2型糖尿病模型的初步数据显示冠状动脉氧化应激，AGE积累和AGE受体（RAGE）， AT1受体（AT1R）和NADPH氧化酶的Nox-1亚基的表达增加。这些分子变化发生在冠状动脉僵硬和向内结构重塑增加之前。用NADPH氧化酶抑制剂罗布麻肽或AT1R阻滞剂坎地沙坦预处理可减少血管内重构。与Db/ Db对照组相比，Db/ Db小鼠的冠状动脉和冠状动脉VSMC都增加了激酶信号级联的激活，这对血管重塑至关重要。此外，db/db冠状动脉VSMC对Ang II和AGE/RAGE表现出增加的增殖反应。总体假设是，2型糖尿病中Ang II和年龄依赖性氧化应激的增加改变了冠状动脉VSMC表型，增加了增殖和ECM的产生，导致结构重塑和硬度增加。目的1将利用药物抑制剂和NADPH缺陷小鼠来建立NADPH氧化酶与线粒体诱导的ROS生成在糖尿病诱导的冠状动脉重构中的相对贡献。Aim 2的研究将利用AGE/RAGE通路的分子和转基因破坏来确定AGE/RAGE调节冠状动脉重塑和僵硬的分子机制。Aim 3的研究将确定RAS、AGE/RAGE和氧化应激在调节冠状动脉重构中的分子相互作用。综合的生化和转基因方法将用于定义调节VSMC生长和ECM积累的信号通路。公共卫生相关性：拟议的研究将确定促进2型糖尿病诱导的冠状动脉疾病的独特分子靶点。冠状动脉硬度的增加，以及管腔的变窄，导致运动和劳累时流向心脏的血液减少，导致心肌梗死。

DESCRIPTION (provided by applicant): Type 2 diabetes causes cardiovascular complications including coronary artery disease. Little is known about the effects of diabetes on structural remodeling of coronary arteries. Alterations in coronary artery lumen diameter and stiffness result in reduced coronary flow reserve. Both the composition of the extracellular matrix (ECM) and vascular smooth muscle cell (VSMC) growth are key determinants of artery remodeling. Chronic hyperglycemia-induced formation of advanced glycation products (AGEs) and activation of the renin-angiotensin system (RAS) are increased in Type 2 diabetes and are related to increased oxidative stress. Preliminary data using the db/db mouse model of Type 2 diabetes indicate increased coronary artery oxidative stress, AGE accumulation and expression of AGE receptors (RAGE), AT1 receptors (AT1R) and the Nox-1 subunit of the NADPH oxidase. These molecular changes preceded increased coronary artery stiffness and inward structural remodeling. Pretreatment with the NADPH oxidase inhibitor apocynin or the AT1R blocker candesartan reduced inward vessel remodeling. Compared to Db/db controls, both coronary arteries and coronary VSMC from db/db mice have increased activation of kinase signaling cascades that are crucial for vessel remodeling. Moreover, db/db coronary VSMC exhibit increased proliferative responses to Ang II and AGE/RAGE. The overall hypothesis is that increased Ang II- and AGE-dependent oxidative stress in Type 2 diabetes alters coronary artery VSMC phenotype to increase proliferation and ECM production, leading to structural remodeling and increased stiffness. Aim 1 will utilize pharmacological inhibitors and NADPH deficient mice to establish the relative contribution of the NADPH oxidase vs. mitochondrial-induced ROS generation in diabetes-induced coronary artery remodeling. Studies in Aim 2 will use molecular and transgenic disruption of the AGE/RAGE pathway to define the molecular mechanisms by which AGE/RAGE regulate coronary artery remodeling and stiffness. Studies in Aim 3 will define the molecular interplay between RAS, AGE/RAGE, and oxidative stress in the regulation of coronary artery remodeling. A comprehensive biochemical and transgenic approach will be used to define the signaling pathways that regulate VSMC growth and ECM accumulation. PUBLIC HEALTH RELEVANCE: The proposed studies will identify unique molecular targets that contribute to Type 2 diabetes- induced coronary artery disease. Increased stiffness of coronary arteries, along with narrowing of the lumen, causes decreased blood flow to the heart during exercise and exertion, leading to myocardial infarction.