Cardiac Lipotoxicity and Ceramide Metabolism in Heart Failure

描述（由申请人提供）：心力衰竭（HF）的患病率在全球范围内不断增加，发病率和死亡率较高。晚期HF患者会出现严重的代谢异常，包括胰岛素抵抗、细胞因子激活和衰竭心肌中的异常氧化代谢。我们以前的工作已经表明，在失败的人心肌中积累的有毒脂质中间体神经酰胺和甘油二酯，这些有毒脂质诱导转录的变化，受损的细胞能量代谢和抑制胰岛素信号。此外，初步的动物研究表明，在衰竭心肌中长链神经酰胺的积累。一个促凋亡状态和增强的蛋白水解蛋白分解已知与有毒脂质中间体发展在先进的HF。因此，毒性脂质中间体（如长链神经酰胺）的蓄积可能是导致晚期HF功能受损和进行性心脏重塑的细胞代谢改变和蛋白水解之间的关键联系。本申请的中心假设是长链神经酰胺物质的脂毒性积累有助于结构性神经酰胺化。 和功能性心肌改变。我们假设，脂毒性是心肌功能障碍的一个关键手段，但存在不同的特点定义的基础心肌病。在缺血性和非缺血性心肌病患者和非疾病对照的心肌中，我们将使用LC/MS技术分析神经酰胺、二酰基甘油酯、甘油三酯、脂肪酸、酰基肉毒碱、脂氧素和消退素的心肌脂质组成。我们还将研究通过左心室辅助装置（LVAD）放置机械卸载对心肌代谢紊乱（AIM 1）的影响。此外，我们将分析控制基因和microRNA表达的途径，并将其与脂质组成分析的结果联系起来（AIM 2）。最后，我们将分析人类缺血性和非缺血性心肌病动物模型中的心脏脂质组成，并测试神经酰胺合成的从头和补救途径的药理学和遗传抑制是否会影响长链神经酰胺蓄积和进行性心脏重塑（AIM 3）。在实现这一目标的建议，我们将扩大理解的关键机制，心肌结构和功能紊乱的HF。这项研究的一个主要优势是能够测试长链神经酰胺积累对心肌重塑的影响。此外，我们将确定与对照组相比，晚期HF患者的心肌脂质池以及衰竭心肌的机械卸载的影响。这些研究将确定HF患者的新分子和功能靶点。因此，拟议的工作将为更广泛的临床目标奠定重要的基础，以确定和加强治疗策略，以修改HF心脏代谢的分子和转录模式。

DESCRIPTION (provided by applicant): The prevalence of heart failure (HF) is increasing throughout the world with high morbidity and mortality. Patients with advanced HF develop profound metabolic abnormalities including insulin resistance, cytokine activation and abnormal oxidative metabolism in the failing myocardium. Our previous work has shown accumulation of the toxic lipid intermediates ceramide and diacylglycerol in failing human myocardium and that these toxic lipids induce transcriptional changes, impaired cellular energy metabolism and inhibit insulin signaling. Further, preliminary animal studies revealed accumulation of long-chain ceramides in the failing myocardium. A pro-apoptotic state and enhanced proteolytic protein breakdown known to be associated with toxic lipid intermediates develops in advanced HF. Therefore, accumulation of toxic lipid intermediates such as long-chain ceramides might constitute a key link between altered cellular metabolism and proteolysis leading to impaired function and progressive cardiac remodeling in advanced HF. The central hypothesis of this application is that lipotoxic accumulation of long-chain ceramide species contributes to structural and functional myocardial changes in HF. We hypothesize that lipotoxicity is a key means of myocardial dysfunction but that distinct characteristics exist defined by the underlying cardiomyopathy. In myocardium from patients with ischemic and non-ischemic cardiomyopathies and non- diseased controls, we will analyze the myocardial lipid composition of ceramides, diacylglycerides, triglycerides, fatty acids, acylcarnitines, lipoxins and resolvins using LC/MS techniques. We also will study the impact of mechanical unloading through left ventricular assist device (LVAD) placement on myocardial metabolic derangements (AIM 1). Further, we will analyze pathways controlling gene and microRNA expression and link these to the results of the lipid composition analyses (AIM 2). Finally, we will analyze the cardiac lipid composition in animal models of human ischemic and non-ischemic cardiomyopathies and test whether pharmacologic and genetic inhibition of the de novo and salvage pathway of ceramide synthesis affects long-chain ceramide accumulation and progressive cardiac remodeling (AIM 3). In achieving the goals of this proposal, we will expand the understanding of key mechanisms underlying myocardial structural and functional derangements in HF. A major strength of this investigation is the ability to test the impact of long-chain ceramide accumulation on myocardial remodeling. Further, we will define the myocardial lipid pool in patients with advanced HF compared to controls and the impact of mechanical unloading of the failing myocardium. These studies will define new molecular and functional targets in patients with HF. The proposed work will, therefore, lay critical groundwork for broader clinical goals to define and enhance therapeutic strategies to modify molecular and transcriptional patterns of cardiac metabolism in HF.