Oxidative stress and aortic valve disease

描述(由申请人提供)： 主动脉瓣置换术是有症状的钙化主动脉瓣狭窄(AVS)患者的主要治疗方法，也是最常见的瓣膜外科手术(&gt；每年进行250,000例)。狭窄瓣膜在组织学上类似于动脉粥样硬化病变，申请人的实验室显示，在高胆固醇血症小鼠的动脉粥样硬化病变和狭窄瓣膜中，超氧化物显著增加(LDLR-/-/ApoB100/100)。然而，尽管动脉粥样硬化病变中的超氧化物由于NAD(P)H氧化酶活性的增加而增加，但申请人的初步数据表明，导致狭窄瓣膜中超氧化物歧化的机制是根本不同的，可能是由于超氧化物歧化酶(SOD)活性的降低和一氧化氮合酶的解偶联。申请人开发了超声心动图和磁共振成像方法来评估高胆固醇血症小鼠主动脉瓣功能随时间的变化，并开发了共聚焦显微镜和激光捕获显微解剖来研究这些变化背后的分子机制。申请人提出了两个主要目标：1)研究治疗高胆固醇血症对主动脉瓣疾病进展的影响，2)确定导致主动脉瓣疾病发病的分子机制。在K99/指导阶段的资助中，申请者将研究积极降脂对高脂血症小鼠瓣膜疾病进展的影响，使用“遗传开关”来使胆固醇水平正常化(使用Ldlr-/-/Apob100/100/Mttpfl/fl/Mx1Cre/小鼠，也称为“逆转”小鼠)。在资助的R00/非依赖性阶段，申请者将检查容易发生主动脉瓣狭窄的机制。在R00阶段的第一部分，申请者将使用高脂血症MnSOD缺陷和高脂血症MnSOD过表达的小鼠来确定线粒体衍生的氧化应激在AVS进展中的作用。在Rod阶段的第二部分，申请者将确定一氧化氮合酶(NOS)辅助因子枯竭和内源性NOS抑制剂不对称二甲基精氨酸(ADMA)在体外正常和狭窄人类瓣膜氧化应激中的作用。申请人还将研究DDAH1(一种参与ADMA降解的酶)在高脂血症DDAH1缺陷和高脂血症DDAH1过表达小鼠AVS进展中的作用。总而言之，这些研究将为AVS的病理生理学以及治疗高胆固醇血症的效果提供新的见解，从而将导致预防和治疗AVS的新方法。

DESCRIPTION (provided by applicant): 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 (> 250,000 performed annually). Stenotic valves are histologically similar to atherosclerotic lesions, and the applicant's laboratory has shown significant increases in superoxide in atherosclerotic lesions and stenotic valves in hypercholesterolemic mice (ldlr-/-/ApoB100/100). 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. The applicant has developed 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. The applicant proposes two main goals: 1) to examine the effects of treating hypercholesterolemia on the progression of aortic valve disease, and 2) to identify molecular mechanisms contributing to the pathogenesis of aortic valve disease. During the K99/Mentored phase of the grant, the applicant will examine the effects of aggressive lipid lowering on the progression of valve disease in hyperlipidemic mice, using a "genetic switch" to normalize cholesterol levels (using Ldlr-/-/Apob100/100/ Mttpfl/fl/Mx1Cre+/+ mice, also called "Reversa" mice). During the R00/lndependent phase of the grant, the applicant will examine mechanisms that predispose to the development of aortic valve stenosis. In the first portion of the R00 phase, the applicant will determine the role of mitochondria-derived oxidative stress on the progression of AVS using hyperlipidemic MnSOD-deficient and hyperlipidemic MnSOD-overexpressing mice. In the second portion of the ROD phase, the applicant will 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. The applicant 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.