Oxidative stress and aortic valve disease

主动脉瓣置换术是症状性钙化性主动脉瓣狭窄（AVS）患者的主要治疗方法，也是全球最常见的瓣膜外科手术。狭窄瓣膜在组织学上类似于动脉粥样硬化病变，并且申请人的实验室已经显示在高胆固醇血症小鼠中动脉粥样硬化病变和狭窄瓣膜中超氧化物的显著增加（Idlr-/-/ApoBIO 0/100）。然而，虽然动脉粥样硬化病变中的超氧化物由于NAD（P）H氧化酶活性增加而增加，但申请人的初步数据表明，导致狭窄瓣膜中超氧化物增加的机制根本不同，并且可能是由于超氧化物歧化酶（SOD）酶活性降低和一氧化氮合酶解偶联。我们将使用超声心动图和磁共振成像的方法来评估主动脉瓣功能的变化， 高胆固醇血症小鼠随时间的变化，以及共聚焦显微镜和激光捕获显微切割来检查这些变化背后的分子机制。我们提出两个主要目标：1）使用高脂血症MnSOD缺陷和高脂血症MnSOD过表达小鼠来检查源自于动脉的氧化应激对AVS进展的影响。2)确定一氧化氮合酶（NOS）辅因子耗竭和内源性NOS抑制剂不对称二甲基精氨酸（ADMA）对离体正常和狭窄人类瓣膜氧化应激的作用。我们还将研究DDAH 1（一种参与ADMA降解的酶）在AVS进展中的作用，使用高脂血症DDAH 1缺陷和高脂血症DDAH 1过表达小鼠。总的来说，这些研究将为AVS的病理生理学以及高胆固醇血症的治疗效果提供新的见解，从而将导致预防和治疗AVS的新方法。

Replacement of the aortic valve is the primary treatment for patients with symptomatic, calcific aortic valve stenosis (AVS), and is the most common valvular surgical procedure performed worldwide. Stenotic valves are histologically similar to atherosclerotic lesions, and the applicant's laboratory has shown significant ncreases in superoxide in atherosclerotic lesions and stenotic valves in hypercholesterolemic mice {Idlr-/-/ApoBIOO/100). However, while superoxide in atherosclerotic lesions is increased due to increased NAD(P)H oxidase activity, the applicant's preliminary data suggest that mechanisms contributing to increased superoxide in stenotic valves are fundamentally different, and are likely due to reductions in superoxide dismutase (SOD) enzyme activity and uncoupling of nitric oxide synthase. We will use echocardiographic and magnetic resonance imaging methods to evaluate the changes in aortic valve function in hypercholesterolemic mice over time, and confocal microscopy and laser capture microdissection to examine molecular mechanisms underlying these changes. We propose two main goals: 1) to examine the effects of mitochondria-derived oxidative stress on the progression of AVS using hyperlipidemic MnSOD-deficient and hyperlipidemic MnSOD-overexpressing mice. 2) to determine the role of nitric oxide synthase (NOS) cofactor depletion and the endogenous NOS inhibitor asymmetric dimethylarginine (ADMA) on oxidative stress in normal and stenotic human valves ex vivo. We will also examine the role of DDAH1 (an enzyme involved in ADMA degradation) in the progression of AVS using hyperlipidemic DDAH1-deficient and hyperlipidemic DDAH1-overexpressing mice. Collectively, these studies will lend novel insights into the pathophysiology of AVS as well as the effects of treatment of hypercholesterolemia, and thus will lead to new approaches to prevent and treat AVS.