Dual Functionality of Ceramide in Human Microvascular Endothelial Function

项目摘要 血浆神经酰胺水平升高是主要不良心脏事件(MACE)的独立危险因素 与心血管疾病有关，包括冠状动脉疾病(CAD)和心力衰竭 保留射血分数(HFpEF)。内皮微血管功能障碍，一氧化氮(NO)的丧失- 中介性扩张为血流(Flow-Induced Diplation；FID)，先于CAD发展，随后发生 长期接触外源性神经酰胺。在疾病期间、在急性应激之后(例如，高压)或在 慢性神经酰胺治疗，FID是通过利用线粒体衍生的过氧化氢(H_2O_2)维持的。 尽管过氧化氢在引起扩张方面有效，但与一氧化氮的抗炎作用不同，过氧化氢促进炎症反应。 血管系统和周围实质组织内的环境。神经酰胺的作用机制(S) 促进线粒体过氧化氢介导的FID尚不清楚。有趣的是，神经酰胺也被牵连到 作为NO产生过程中的一个关键信号成分。神经酰胺代谢物鞘氨醇-1-磷酸 (S1P)对血管内皮细胞起相反作用，促进NO的形成，并可能解释阳性反应 神经酰胺相关的血管效应。关于的双重功能存在很大的知识差距 人体微血管内皮细胞内的神经酰胺。我们假设神经酰胺的形成是一种 NO介导的FID中的关键机械成分，长时间暴露会启动一系列信号级联反应 结果剪切力引起线粒体过氧化氢的释放。我们的目标是：1)确定 神经酰胺在维持人体微循环内NO介导的FID中的必要作用，以及2) 应激或疾病中神经酰胺形成启动FID转化的机制(S) 从NO到线粒体来源的过氧化氢的介体。使用一种新的方法，这些机械研究将被 作为补充，首次进行了人体活体研究，以检验血浆神经酰胺升高对外周血的影响 微血管功能。本申请中提出的翻译研究将加深我们对 神经酰胺在健康、疾病和急性应激后的信号转导。这一信息将提供新的目标 对心血管疾病的高危人群进行治疗干预，包括冠心病和 HFpEF。

Project Summary Elevated levels of plasma ceramide are an independent risk factor for major adverse cardiac events (MACE) and are associated with cardiovascular diseases including coronary artery disease (CAD) and heart failure with preserved ejection fraction (HFpEF). Endothelial microvascular dysfunction, the loss of nitric oxide (NO)- mediated dilation to flow (flow-induced dilation; FID), precedes the development of CAD and occurs following chronic exposure to exogenous ceramide. During disease, following acute stress (e.g. high pressure), or after chronic ceramide treatment, FID is maintained by utilizing mitochondrial-derived hydrogen peroxide (H2O2). Although effective at eliciting dilation, unlike the anti-inflammatory effects of NO, H2O2 promotes an inflammatory environment within the vasculature and surrounding parenchymal tissue. The mechanism(s) by which ceramide promotes mitochondrial H2O2-mediated FID remains unknown. Interestingly, ceramide has also been implicated as a critical signaling component in the generation of NO. The ceramide metabolite sphingosine-1-phosphate (S1P) exerts opposing effects on the endothelium, promotes the formation of NO, and may explain the positive vascular effects associated with ceramide. A large knowledge gap exists regarding the dual functionality of ceramide within the human microvascular endothelium. We hypothesize that while ceramide formation is a critical mechanistic component in NO-mediated FID, prolonged exposure initiates a signaling cascade that results in the release of mitochondrial H2O2 in response to shear. Our aims are as follows; 1) determine the necessary role of ceramide in maintaining NO-mediated FID within the human microcirculation, and 2) investigate the mechanism(s) by which ceramide formation during stress or disease initiates the transition in FID mediator from NO to mitochondrial-derived H2O2. Using a novel approach, these mechanistic studies will be complemented by the first human in vivo study to examine the effect of elevated plasma ceramide on peripheral microvascular function. The translational studies proposed in this application will enhance our understanding of ceramide signaling during health, disease, and following acute stress. This information will provide new targets for therapeutic intervention in individuals at risk for developing cardiovascular disease including CAD and HFpEF.