Does Diabetic Hyperglycemia Regulate Atherosclerosis Progression and Regression?

描述（由申请人提供）： 糖尿病与动脉粥样硬化相关的心血管疾病（包括外周动脉疾病（PAD））增加2至4倍相关。尽管存在这种关联，但对于糖尿病高血糖加速动脉粥样硬化和PAD并发症（包括肢体丧失和过早死亡）的机制知之甚少。此外，尚不清楚高血糖是否会损害动脉粥样硬化的消退。不幸的是，现有的动脉粥样硬化小鼠模型的研究经常被最近认识到的高血糖增加糖尿病小鼠血浆胆固醇水平的影响所破坏。研究发现高血糖会加速动脉粥样硬化，也报告糖尿病小鼠血浆胆固醇增加。此外，缺乏合适的动脉粥样硬化消退的小鼠模型阻碍了旨在解决糖尿病高血糖对动脉粥样硬化消退的影响的研究，这是一种有前途的心血管疾病临床治疗策略。我们建议通过研究我们新开发的自发性和可逆性血脂异常和动脉粥样硬化的小鼠模型来克服这些局限性，该模型被称为低密度脂蛋白受体缺陷的低形态载脂蛋白E小鼠（Apoeh/hLdlr-/-Mx 1-Cre小鼠）。当喂食低脂食物时，这些小鼠虽然中度血脂异常，但对进一步的高血糖诱导的高胆固醇血症具有抗性。此外，他们在12至14个月大时发展为闭塞性外周动脉粥样硬化，在饮食中易患严重肢体缺血和过早死亡。值得注意的是，他们的血脂异常可以通过诱导型Cre激活介导的亚型Apoe等位基因的条件性基因修复永久降低，这导致动脉粥样硬化在2周内消退。在目标1中，我们将研究高血糖和血糖正常的Apoeh/hLdlr-/-Mx 1-Cre小鼠，以评估12月龄小鼠中闭塞性外周动脉粥样硬化和PAD症状形式的程度和频率。我们还将检验以下假设：在没有额外血脂异常的情况下，高血糖症会增强全身炎症和外周动脉血管细胞的促炎状态。然后，我们将测试的假设，增强血管炎症增加外周动脉单核细胞的招聘，高血糖症提高细胞内游离胆固醇水平，从而促进未折叠的蛋白质反应和过早凋亡的巨噬细胞泡沫细胞。最后，我们将检验从高血糖Apoeh/hLdlr-/-Mx 1-Cre小鼠中分离的高密度脂蛋白将显示出降低的促进脂质消除和抑制炎症的能力，而低密度脂蛋白将具有相反的作用的假设。Apoeh/hLdlr-/-Mx 1-Cre小鼠血脂异常和动脉粥样硬化的快速逆转为解决与动脉粥样硬化消退相关的机制提供了一种强大的新方法。因此，在目的2中，我们将检验以下假设：高血糖症损害血管细胞的转录重编程，从而损害动脉脂质的去除、巨噬细胞的流出和胶原蛋白的积累以响应脂质降低。接下来，我们将探索治疗性胰岛素治疗在高血糖Apoeh/hLdlr-/-Mx 1-Cre小鼠中增强动脉粥样硬化消退的效用。我们的长期目标是确定可以作为治疗靶点的机制，以延迟动脉粥样硬化的进展并加速其消退，作为糖尿病患者PAD的治疗方法。 公共卫生相关性： 拟议研究项目与退伍军人当前和未来医疗保健需求的相关性。当全身的动脉被胆固醇和脂肪阻塞时，就会发生外周动脉疾病（PAD）。每年，成千上万的退伍军人接受手术治疗，以恢复他们的腿部，肾脏和大脑的血液流动。还有数千人因截肢而遭受永久残疾的痛苦，许多人必须接受终身透析，其他人则死于中风和心脏病发作。新的实验疗法表明，降低血液胆固醇可以改善阻塞动脉的血流。不幸的是，糖尿病退伍军人患PAD及其并发症的风险更大。为什么糖尿病和高血糖会增加PAD尚不清楚。这项拨款提案中的实验将利用首席研究员开发的基因工程小鼠来研究高血糖如何加速动脉阻塞并延迟血脂降低后的消退。我们的目标是发现新的方法来阻止阻塞和加速患有PAD的糖尿病退伍军人的动脉畅通。

DESCRIPTION (provided by applicant): Diabetes is associated with a 2- to 4-fold increase in atherosclerosis-related cardiovascular disease including peripheral arterial disease (PAD). Despite this association, little is known about the mechanisms by which diabetic hyperglycemia can accelerate atherosclerosis and complication of PAD that include limb loss and premature death. Moreover, whether hyperglycemia can impair the regression of atherosclerosis is not known. Unfortunately, studies of existing mouse models of atherosclerosis were often marred by the recently recognized effect by which hyperglycemia increases plasma cholesterol levels in diabetic mice. Studies in which hyperglycemia was found to accelerate atherosclerosis also reported increased plasma cholesterol in diabetic mice. Moreover, the lack of suitable mouse models of atherosclerosis regression have hampered studies designed to address the effects of diabetic hyperglycemia on atherosclerosis regression, a promising clinical treatment strategy for cardiovascular disease. We propose to overcome these limitations by studying our newly developed mouse model of spontaneous and reversible dyslipidemia and atherosclerosis called hypomorphic apolipoprotein E mice deficient in the low density lipoprotein receptor (Apoeh/hLdlr-/-Mx1-Cre mice). When fed a low-fat chow diet, these mice, while moderately dyslipidemic, are resistant to further hyperglycemia-induced hypercholesterolemia. Moreover, they develop occlusive peripheral atherosclerosis by 12 to 14 months of age, predisposing to critical limb ischemia and premature death while on a chow diet. Remarkably, their dyslipidemia can be permanently lowered by conditional gene repair of the hypomorphic Apoe allele mediated by inducible Cre activation, which results in atherosclerosis regression within 2 weeks. In Aim 1, we will study hyperglycemic and normoglycemic Apoeh/hLdlr-/-Mx1-Cre mice to assess the extent and frequency of occlusive peripheral atherosclerosis and symptomatic forms of PAD in 12 month old mice. We will also test the hypothesis that in the absence of added dyslipidemia, hyperglycemia enhances systemic inflammation and the pro-inflammatory state of vascular cells in peripheral arteries. We will then test the hypothesis that enhanced vascular inflammation augments monocyte recruitment in peripheral arteries, and that hyperglycemia raises intracellular free cholesterol levels, thereby promoting the unfolded protein response and premature apoptosis of macrophage foam cells. Lastly, we will test the hypothesis that high density lipoproteins isolated from hyperglycemic Apoeh/hLdlr-/-Mx1-Cre mice will display a reduced ability to promote lipid elimination and suppress inflammation, and that low density lipoproteins will have opposite effects. The rapid reversal of dyslipidemia and atherosclerosis in Apoeh/hLdlr-/-Mx1-Cre mice provides a powerful new approach to address mechanisms associated with atherosclerosis regression. Thus, in Aim 2, we will test the hypothesis that hyperglycemia impairs transcriptional reprogramming of vascular cells and thereby the removal of arterial lipid, the egress of macrophages and the accumulation of collagen in response to lipid lowering. Next, we will explore the utility of therapeutic insulin treatment to enhance atherosclerosis regression in hyperglycemic Apoeh/hLdlr-/-Mx1-Cre mice. Our long-term goals are to identify mechanisms that could serve as therapeutic targets to delay the progression and accelerate the regression of atherosclerosis as treatments for PAD in diabetic individuals. PUBLIC HEALTH RELEVANCE: Relevance of the proposed research project to current and future health care needs among Veterans. Peripheral arterial disease (PAD) occurs when arteries throughout the body become obstructed by cholesterol and fat. Every year, thousands of veterans receive surgical treatments to restore blood flow to their legs, kidneys and brain. Thousands more experience the pain of being permanently disabled because of the amputation of feet and legs, while many must receive lifelong dialysis and others die of strokes and heart attacks. New experimental therapies have shown that lowering blood cholesterol can improve blood flow in obstructed arteries. Unfortunately, diabetic veterans are even more at risk of PAD and its complications. Why diabetes and high blood sugar increase PAD is not known. Experiments in this grant proposal will make use of genetically engineered mice developed by the Principal Investigator to investigate how high blood sugar can accelerate arterial obstructions and delay their resolution after blood lipid lowering. Our goal is to discover new ways to stop the clogging and accelerate the unclogging of arteries in diabetic veterans who suffer from PAD.