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增加2到4倍，包括外周动脉疾病(PAD)。尽管存在这种关联，但人们对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，高血糖是否会损害动脉粥样硬化的消退尚不清楚。不幸的是，对现有的小鼠动脉粥样硬化模型的研究经常受到最近公认的高血糖增加糖尿病小鼠血浆胆固醇水平的影响的影响。发现高血糖加速动脉粥样硬化的研究也报告了糖尿病小鼠血浆胆固醇的增加。此外，缺乏合适的动脉粥样硬化消退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限制，该模型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-/-Mx1-Cre小鼠)。当喂食低脂饮食时，这些小鼠虽然有中度的血脂异常，但对进一步的高血糖诱导的高胆固醇血症具有抵抗力。此外，他们在12到14个月大的时候会出现闭塞性外周动脉粥样硬化，在饮食中容易出现严重的肢体缺血和过早死亡。值得注意的是，通过诱导Cre激活介导的APOE等位基因条件性修复，可以永久性地降低他们的血脂异常，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正常血糖Apoeh/hLdlr-/-Mx1-Cre小鼠，以评估12月龄小鼠闭塞性外周动脉粥样硬化的程度和频率以及PAD的症状形式。我们还将检验这一假设，即在没有额外的血脂异常的情况下，高血糖会增强全身炎症和外周动脉血管细胞的促炎状态。然后，我们将检验这一假说，即增强的血管炎症增加了外周动脉中单核细胞的募集，高血糖提高了细胞内游离胆固醇水平，从而促进了巨噬细胞泡沫细胞的未折叠蛋白反应和过早凋亡。最后，我们将测试从高血糖Apoeh/hLdlr-/-Mx1-Cre小鼠中分离出的高密度脂蛋白将显示出促进脂质清除和抑制炎症的能力降低的假设，而低密度脂蛋白将具有相反的作用。Apoeh/hLdlr-/-Mx1-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有力的新方法。因此，在目标2中，我们将检验这一假设，即高血糖损害血管细胞的转录重编程，从而损害动脉脂肪的清除，巨噬细胞的外泄和胶原的积累，以响应降脂。接下来，我们将探索治疗性胰岛素治疗在促进高血糖Apoeh/hLdlr-/-Mx1-Cre小鼠动脉粥样硬化消退方面的作用。我们的长期目标是确定可以作为治疗靶点的机制，以延缓和加速动脉粥样硬化的进展和消退，作为糖尿病患者PAD的治疗方法。 公共卫生相关性： 建议的研究项目与退伍军人当前和未来的卫生保健需求的相关性。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。每年，数以千计的退伍军人接受手术治疗，以恢复腿部、肾脏和大脑的血液流动。还有数千人因双脚和双腿被截肢而遭受永久性残疾的痛苦，许多人必须接受终身透析，另一些人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液流动。不幸的是，糖尿病退伍军人患PAD及其并发症的风险更大。糖尿病和高血糖增加PAD的原因尚不清楚。这项拨款计划中的实验将利用首席调查员开发的基因工程小鼠来研究高血糖如何在降血脂后加速动脉阻塞和延迟它们的消退。我们的目标是找到新的方法来阻止动脉阻塞，并加速患有PAD的糖尿病退伍军人的动脉疏通。

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.