Differential Macro- and Micro-Vascular Remodeling in Type 2 Diabetes and Metabolic Syndrome

描述（由申请人提供）：2型糖尿病（T2DM）患者的心脏病与冠状动脉疾病（CAD）的严重程度直接相关，导致冠状动脉血流受损和心肌梗死（MI）的风险增加。由于心血管疾病是2型糖尿病患者死亡的主要原因，占糖尿病患者死亡总数的65%，因此这在美国和全世界造成了非常严重的健康和经济负担。此外，糖尿病患者发生心肌梗死的可能性是非糖尿病患者的2-4倍。虽然已知动脉粥样硬化和内皮功能障碍是心肌梗死的诱因，但冠状动脉微血管（CRM）重构与大血管（导管动脉）重构在t2dm诱导的心脏病中的相对作用仍不清楚。我们之前的研究表明，从T2DM db/db小鼠或临床前Ossabaw猪met模型中分离的crm在面对大血管僵硬度增加（教条）时，会发生与僵硬度降低相关的内向肥厚重塑（新的和反教条）。CRM重塑伴随着冠状动脉血流量减少，部分依赖于血管平滑肌细胞（VSMC）增殖、弹性细胞外基质（ECM）表达增加和局灶黏附/细胞骨架蛋白表达减少。相比之下，T2DM小鼠大血管的局灶黏附/细胞骨架和ECM蛋白表达增加。这些发现表明，细胞硬度与大血管和冠状动脉微血管ECM之间的密切相互作用决定了T2DM患者的整体血管硬度。我们还观察到，CRM VSMC表现出增生性表型，这与晚期糖基化终产物(AGE)/RAGE通路的信号增强和富含半胱氨酸蛋白2 （CRP2）的表达减少有关，CRP2是VSMC增殖的负调节因子。目前还没有直接研究僵硬度对T2DM VSMC表型的影响。根据我的初步数据，较不僵硬的主动脉壁促进体内增殖性VSMC表型，而较僵硬的主动脉（大血管）壁有利于合成VSMC表型。这些数据表明，CRM重塑的机制与调节大血管重塑的机制有着根本的不同，并且可能代表了决定VSMC表型的病理机制，从而导致糖尿病性心肌梗死。因此，我的总体假设是，宏观和冠状动脉微血管重塑和僵硬的改变反映了细胞的不同贡献

DESCRIPTION (provided by applicant): Heart disease in type 2 diabetes mellitus (T2DM) is directly related to the severity of coronary artery disease (CAD), which results in impaired coronary flow and increased risk of myocardial infarction (MI). This poses a very significant health and economic burden in the U.S. and worldwide since cardiovascular disease is the leading cause or mortality in T2DM, accounting for >65% of all deaths in diabetic patients. Moreover, diabetic patients are 2-4 times more likely to experience MI than non-diabetic patients. While atherosclerosis and endothelial dysfunction are known contributors to MI, the relative contribution of coronary resistance microvessel (CRM) remodeling versus macrovessel (conduit artery) remodeling to T2DM-induced cardiac disease remains largely unknown. We previously showed that CRMs isolated from either T2DM db/db mice or the pre-clinical Ossabaw porcine model of MetS undergo inward hypertrophic remodeling associated with reduced stiffness (novel and anti-dogmatic) in the face of increased macrovascular stiffness (dogmatic). CRM remodeling was accompanied by reduced coronary blood flow and was partially dependent upon vascular smooth muscle cell (VSMC) proliferation, increased expression of elastic extracellular matrix (ECM), and decreased expression of focal adhesion/cytoskeletal proteins. In contrast, focal adhesion/cytoskeletal and ECM protein expression were increased in macrovessels of T2DM db/db mice. These findings point to an intimate interaction between cellular stiffness and the ECM in macro- and coronary micro-vessels that dictates overall vascular stiffness in T2DM. We also observed that CRM VSMCs exhibit a proliferative phenotype that is associated with enhanced signaling by the advanced glycation end products (AGE)/RAGE pathway and decreased expression of cysteine rich-protein 2 (CRP2), which is a negative regulator of VSMC proliferation. There are currently no studies that have directly investigated the effect of stiffness on T2DM VSMC phenotype. Based on my preliminary data, a less stiff CRM wall promotes an in vivo proliferative VSMC phenotype, while the stiffer aortic (macrovascular) wall favors a synthetic VSMC phenotype. These data demonstrate that mechanisms underlying CRM remodeling are fundamentally different from those that regulate macrovascular remodeling and may represent pathologic mechanisms dictating VSMC phenotype, contributing to diabetic MI. Thus, my overall hypothesis is that alterations in macro- and coronary micro-vascular remodeling and stiffness reflect differential contributions of cellular and ECM stiffness that controls VSMC phenotype and may be dictated in part by AGE/RAGE and/or CRP2. The studies outlined in this proposal will investigate these mechanisms comprehensively utilizing a novel decellularization technique in aorta and CRMs, primary VSMC cultures, isolated coronary resistance microvessels, and in vivo analysis of vascular remodeling and blood flow in diabetic mice. During the mentored phase, we will determine the relative contribution of both the ECM and VSMCs to overall vascular stiffness further assess whether stiffness can modulate classical VSMC phenotypes in both macro-vessels and CRMs. The mentored studies will focus heavily on determining the cellular and biomechanical mechanisms underlying these alterations in primary VSMC cultures. During the independent phase, I will determine whether the interplay of stiffness, AGE/RAGE, and CRP2 modulates the phenotype of VSMCs isolated from both diabetic mice and pre-clinical pigs with MetS. Finally, I will evaluate the therapeutic potential of a novel RAGE antagonist, FPS-ZM1, in reducing adverse vascular remodeling in T2DM mice. This transition award will allow me access to additional mentoring necessary for future success as a competitive and successful independent investigator. This proposal includes a comprehensive training plan that will be overseen by members of a mentoring committee with expertise that encompasses vascular signaling and biomechanics, extracellular matrix, and coronary complications of diabetes and metabolic syndrome. Once complete, I will have gained additional expertise in hypothesis generation, experimental design, and data interpretation related to in vitro cellular signaling, vascular mechanics, ECM, and the coronary circulation that will enhance my already sound expertise in ex vivo and in vivo physiology. It will further provide a solid foundation for future studies in whch I would like to investigate (1) the role of endothelial cells in adverse vascular remodeling in T2DM, and (2) the dynamic cross-talk between the coronary circulation and the diabetic heart, since the coronary circulation lies within a complex tissue that exhibits signs of diastolic dysfunction in metabolic conditions such as diabetes and metabolic syndrome. I am committed to maintaining extramural funding from sources such as the NIH to maintain an independent laboratory and training environment, while continuing to make inroads in the cardiovascular complications of metabolic diseases. My past performance is a testament to my excellent technical skills, problem-solving skills, work ethic, and drive that will collectively make me well poised for success.