Dynamic Remodeling From Reversible Ischemia and Sudden Cardiac Arrest

 描述(由申请人提供)： 可逆性缺血和心脏骤停的动态重构室颤(VF)引起的心脏骤停(SCA)是影响退伍军人的主要公共卫生问题 大多数患者都患有严重的、无症状的冠状动脉疾病。许多发生室性心动过速的患者没有心肌梗死的证据，缺血和SCA之间的联系仍不清楚。我们在慢性冬眠心肌猪身上完成的工作表明，可逆性缺血导致固有的心肌适应，保护心肌细胞免受损伤，但增加心脏对自发性室颤的易感性。慢性遥测未能发现心肌缺血的ST段改变，但在室颤前交感神经兴奋时，QT缩短和左心室(LV)舒张末压力升高。这与幸存者不同，在SCA前一周不存在。有限的心肌蛋白质组图谱显示多种糖酵解酶减少，这与冬眠心肌存活者的上调形成对比。这些变化可能通过减少糖酵解产生的ATP，开放依赖于ATP的钾通道(导致QT缩短)和降低SR钙ATPase活性(升高细胞内钙和左室舒张末压)来促进致死性室性心律失常。我们的中心假设是，由于冠状动脉狭窄的进展而导致的缺血诱导的适应导致动态的分子重构，在交感神经激活期间短暂地增加了对VT/VF的易感性。我们将初步确定ICD从SCA抢救出来的猪是否存在糖酵解功能障碍(酶活性降低和PET FDG摄取)。Candi-Date血浆生物标记物将进行评估，以确定它们在SCA之前是否有差异升高。这些研究将与基于发现的蛋白质组学方法相辅相成，这些方法使用基于组织和血液的定量无标记离子电流LC/MS图谱。这将使我们能够更全面地识别其他受损的心肌机制，以及识别新的循环血浆生物标记物，这些标记物在发生室速/室颤的动物与存活的动物中升高。我们将通过解决两个特定目标来实现这一点：特定目标1-使用可植入心脏除颤器终止SCA，确定与冬眠心肌存活的动物相比，是否存在不同于缺血诱导的蛋白质重构。假设1A：存活患者的心肌糖酵解酶活性上调，但在室速/室颤发生时下调。假设1B-冬眠心肌存活者糖酵解蛋白和酶活性的减少将伴随FDG摄取的减少和摄取的增加。假设1C-基于发现的基于无标记离子电流的LC/MS组织蛋白质组学分析将识别在发生室速/室颤的动物与存活的动物中发生改变的其他新的蛋白质变化。具体目标2-确定候选生物标记物小组或血清蛋白质组学分析是否可以识别在SCA发展之前选择性预测室速/室颤风险的新生物标记物。假设2A-虽然基于CK-MB的组织坏死将消失，但与幸存者相比，血清TnI和BNP将在SCA之前一过性升高。假设2B-基于Discovery的血清蛋白质组学分析将识别预测SCA风险的新生物标记物与存活冬眠心肌的动物相比。该项目具有很高的翻译相关性，因为它使用了一个临床前模型来研究具有许多慢性冠状动脉疾病特征的SCA。识别分子心肌细胞重构的瞬时靶点以及能够在事件发生前预测SCA风险的新的循环生物标志物将填补关键的知识空白，并导致改善SCA的风险分层和预防。

 DESCRIPTION (provided by applicant): Dynamic Remodeling from Reversible Ischemia and Sudden Cardiac Arrest Sudden cardiac arrest (SCA) from ventricular fibrillation (VF) is a major public health problem affecting Veterans and the majority of victims have severe, asymptomatic coronary artery disease. Many patients developing VF have no evidence of a myocardial infarction and the link between ischemia and SCA remains unclear. Our completed work in swine with chronic hibernating myocardium has demonstrated that reversible ischemia leads to intrinsic myocardial adaptations that protect myocytes from injury yet increase vulnerability of the heart to spontaneous VF. Chronic telemetry has failed to identify ST changes indicative of ischemia but has re- vealed QT shortening and elevated left ventricular (LV) end-diastolic pressure during sympathetic activation immediately preceding VF. This differs from survivors and is not present the week before SCA. Limited myo- cardial proteomic profiling has demonstrated reductions in multiple glycolytic enzymes that contrast with their upregulation in survivors with hibernating myocardium. These changes could promote lethal ventricular ar- rhythmias by reducing glycolytically derived ATP, opening ATP-dependent potassium channels (resulting in QT shortening) and reducing SR calcium ATPase activity (elevating cytosolic calcium and LV end-diastolic pres- sure). Our central hypothesis is that ischemia-induced adaptations resulting from the progression of a coronary stenosis leads to dynamic molecular remodeling that transiently increases the vulnerability to VT/VF during sympathetic activation. We will initially determine whether there is a functional impairment of glycolysis (reduced enzyme activity and PET FDG uptake) in swine rescued from SCA with an ICD. Candi- date plasma biomarkers will be evaluated to identify if they are differentially elevated prior to SCA. These stud- ies will be complimented with discovery-based proteomic approaches employing quantitative label-free ion cur- rent-based LC/MS profiling of tissue and blood. This will allow us to more completely identify additional myo- cardial mechanisms that are impaired as well as identify novel circulating plasma biomarkers that are elevated in animals developing VT/VF vs. survivors. We will accomplish this by addressing two Specific Aims: Specific Aim 1 - Using an implantable cardiac defibrillator to abort SCA, determine whether there is differential ischemia-induced protein remodeling in comparison to animals that survive with hibernating myocardium. Hypothesis 1A - The activity of myocardial glycolytic enzymes is upregulated in survivors but down- regulated at the time that VT/VF develops. Hypothesis 1B - Reductions in glycolytic proteins and enzyme activity will be accompanied by reductions in FDG uptake vs. increased uptake in survivors with hibernating myocardium. Hypothesis 1C - Discovery-based label free ion current-based LC/MS tissue proteomic profiling will identify additional novel protein changes that are altered in animals developing VT/VF vs. survivors. Specific Aim 2 -Determine whether a candidate biomarker panel or serum proteomic profiling can identify novel biomarkers that selectively predict the risk of VT/VF before SCA develops. Hypothesis 2A - While tissue necrosis based on CK-MB will be absent, serum TnI and BNP will be- come transiently elevated prior to SCA as compared to survivors. Hypothesis 2B - Discovery based serum proteomic profiling will identify novel biomarkers predicting the risk of SCA vs. animals with hibernating myocardium that survive. The project has high translational relevance since it employs a preclinical model to study SCA that has many of the features of chronic coronary artery disease. Identifying transient targets of molecular myocyte remodeling as well as novel circulating biomarkers that can predict the risk of SCA before an event would fill a critical knowledge gap and lead to improved risk stratification and prevention of SCA.