Cardiac Lipotoxicity and Ceramide Metabolism in Heart Failure

描述(由申请人提供)：心力衰竭(HF)的患病率在全世界范围内呈上升趋势，发病率和死亡率都很高。晚期心力衰竭患者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的氧化代谢异常。我们以前的工作表明，毒性脂质中间体神经酰胺和二酰甘油在衰竭的人类心肌中积累，这些有毒脂质诱导转录变化，损害细胞能量代谢，并抑制胰岛素信号转导。此外，初步的动物研究显示，在衰竭的心肌中积累了长链神经酰胺。晚期心力衰竭患者出现促凋亡状态和蛋白分解增强，已知与毒性脂质中间体有关。因此，在晚期心力衰竭患者中，毒性脂质中间产物如长链神经酰胺的积聚可能是细胞代谢改变和蛋白分解导致功能受损和进行性心脏重塑的关键环节。这一应用的中心假设是长链神经酰胺物种的脂毒性积累有助于结构 心衰时的心肌功能改变。我们假设脂毒性是心肌功能障碍的关键手段，但潜在的心肌病存在明显的特征。我们将用LC/MS技术分析缺血性和非缺血性心肌病患者和非疾病对照组的心肌组织中神经酰胺、二酰甘油、甘油三酯、脂肪酸、酰卡尼汀、脂氧素和溶血素的脂质组成。我们还将研究通过放置左心室辅助装置(LVAD)进行机械卸载对心肌代谢紊乱的影响(AIM 1)。此外，我们将分析控制基因和microRNA表达的途径，并将这些与脂质成分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的心脏脂质组成，并测试神经酰胺合成的从头和挽救途径的药物和遗传抑制是否影响长链神经酰胺的积累和进行性心脏重构(AIM 3)。为了实现这一建议的目标，我们将扩大对心力衰竭患者心肌结构和功能紊乱的关键机制的理解。这项研究的一个主要优势是能够测试长链神经酰胺积聚对心肌重塑的影响。此外，我们将确定晚期心力衰竭患者与对照组相比的心肌脂质池，以及衰竭心肌机械卸载的影响。这些研究将为心力衰竭患者定义新的分子和功能靶点。因此，拟议的工作将为更广泛的临床目标奠定关键的基础，以定义和加强治疗策略，以改变心衰患者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.