Novel Regulatory Mechanisms in the Human Microcirculation

项目摘要 微血管系统在多种血管病变的发生和后果中起着关键作用。 心血管疾病。对微血管功能的主要评估是通过内皮依赖的NO-1。 介导性扩张作为冠状动脉疾病(CAD)和心肌病的前兆而减少。在……里面 冠状动脉粥样硬化性心脏病患者的人小动脉丧失NO介导的血流介导的扩张(FMD)可通过 内皮线粒体产生过氧化氢(H_2O_2)。虽然两者都是扩张剂，但一氧化氮和过氧化氢 对血管健康的相反作用，NO促进平静，过氧化氢促进血管和 导致动脉粥样硬化的实质炎症。了解导致此切换的机制 介质可能是最大限度地减少组织应激或血管旁分泌氧化还原毒性损伤的关键。 这项研究的目标是确定调控这种从NO到H_2O_2的基本细胞通路。 我们认为，最近被证明是剪切敏感的和细胞功能的基础的两个系统是相连的。 对人体小动脉(HA)的FMD至关重要。第一个是自噬，我们认为这是控制开关 这调节了剪切诱导的NO或过氧化氢的产生。阻止自噬通量减少NO并增强 活性氧(ROS)。第二个途径涉及脂质磷酸酶3(LPP3)，它 通过抑制溶血磷脂酸(LPA)、降低ROS和促进NO来应答切变。单人间 该基因的核苷酸多态在80%的人群中可见，与冠心病的高风险相关。 我们认为，剪切诱导的LPP3激活是维持HA中NO介导的FMD所必需的。 LPP3和自噬都没有与口蹄疫的介体联系起来。我们将研究新鲜的人类冠状动脉 刺激和抑制人微血管内皮细胞中的脂肪小动脉 自噬和LPA以确定它们在口蹄疫中的作用。局部组织的影响可能是深远的，因为 一氧化氮与过氧化氢对心血管功能的影响。我们将检验以下假设： 假设1：自噬在人类冠状动脉中维持NO作为FMD的介体是关键的 微循环。自噬减少会导致转用过氧化氢作为口蹄疫的介体。 假设2：LPP3被微血管内皮细胞剪切上调，导致LPA水解、减弱 内皮ROS，维持一氧化氮合酶依赖的FMD。如果LPP3被机械地链接到 微血管功能障碍，这可能是一个重要的目标，无论是直接或通过LPA，以减少 大量遗传易感冠心病个体的血管炎症。

Project Abstract The microvasculature plays a critical role in the development and consequences of a broad range of cardiovascular diseases. The main assessment of microvascular function is via endothelium-dependent NO- mediated dilation which is reduced as a precursor to coronary artery disease (CAD) and cardiomyopathy. In human arterioles from subjects with CAD loss of NO-mediated flow-mediated dilation (FMD) is compensated by hydrogen peroxide (H2O2) from endothelial mitochondria. Although both are dilators, NO and H2O2 have opposing effects on vascular health, with NO promoting quiescence and H2O2 promoting vascular and parenchymal inflammation leading to atherosclerosis. Understanding mechanisms responsible for this switch in mediator may be key to minimizing tissue stress or injury from vascular paracrine redox toxicity. The goal of this study is to determine fundamental cellular pathways regulating this switch from NO to H2O2. We propose that two systems, recently shown to be shear sensitive and fundamental to cell function are linked as critical for FMD in human arterioles (HA). The first is autophagy which we propose is the controlling switch that regulates shear-induced production of NO or H2O2. Blocking autophagic flux reduces NO and enhances reactive oxygen species (ROS). The second pathway involves lipid phosphate phosphatase 3 (LPP3), which responds to shear by inhibiting lysophosphatidic acid (LPA), lowering ROS and promoting NO. A single nucleotide polymorphism of this gene, seen in 80% of the population is associated with heightened risk for CAD. We propose that shear-induced activation of LPP3 is needed to maintain NO-mediated FMD in HA. Neither LPP3 nor autophagy has been linked to the mediator of FMD. We will study fresh human coronary and adipose arterioles in human microvascular endothelial cells in vitro using stimulators and inhibitors of autophagy and LPA to determine their role in FMD. The local tissue impact can be profound given the different effect of NO vs. H2O2 on cardiovascular function. We will test the following hypotheses: Hypothesis 1. Autophagy is critical in maintaining NO as the mediator of FMD in the human coronary microcirculation. Reduced autophagy leads to a switch to H2O2 as the mediator of FMD. Hypothesis 2. LPP3 is upregulated by microvascular endothelial shear resulting in LPA hydrolysis, attenuation of endothelial ROS, with maintenance of NOS-dependent FMD. If LPP3 is mechanistically linked to microvascular dysfunction, this could be an important target, either directly or through LPA, for reducing the vascular inflammation in a large number of genetically CAD-susceptible individuals.