Does Diabetic Hyperglycemia Regulate Atherosclerosis Progression and Regression?

Robert L.Raffai博士提出的研究项目摘要： 糖尿病与动脉粥样硬化相关的心血管疾病的发病率增加2到4倍，包括 外周动脉疾病(PAD)。尽管存在这种联系，但人们对这种机制知之甚少。 糖尿病高血糖可加速动脉粥样硬化和PAD的并发症，包括肢体丧失和 过早死亡。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 高血糖增加糖尿病小鼠血浆胆固醇水平的公认效应。研究项目： 哪种高血糖被发现会加速动脉粥样硬化也报告了血浆胆固醇在 糖尿病小鼠。此外，缺乏合适的动脉粥样硬化消退的小鼠模型也阻碍了研究。 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，这是一个有希望的研究 心血管疾病的临床治疗策略。 我们建议通过研究我们新开发的自发性和自发性的小鼠模型来克服这些限制 可逆性血脂异常和动脉粥样硬化称为低密度脂蛋白E缺陷小鼠 密度脂蛋白受体(Apoeh/hLdlr-/-Mx1-Cre小鼠)。当喂食低脂肪食物时，这些小鼠 中度血脂异常，对进一步的高血糖引起的高胆固醇血症具有抵抗力。此外，他们还 12至14个月龄时出现闭塞性外周动脉粥样硬化，易患严重肢体缺血 以及在节食时过早死亡。值得注意的是，他们的血脂异常可以永久性地降低 通过可诱导的Cre激活介导的亚型APOE等位基因的条件性基因修复，从而导致 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，以评估其程度和 12月龄小鼠闭塞性外周动脉粥样硬化的发生率和PAD的症状形式。我们会 也要检验这样的假设，即在没有额外血脂异常的情况下，高血糖会增强全身性 炎症和外周动脉血管细胞的促炎状态。然后我们将测试 假设血管炎症增强会增加外周动脉中单核细胞的募集，以及 高血糖会提高细胞内的游离胆固醇水平，从而促进未折叠蛋白的反应 巨噬细胞泡沫细胞过早凋亡。最后，我们将检验高密度的假设 从高血糖Apoeh/hLdlr-/-Mx1-Cre小鼠中分离出的脂蛋白显示促进 消脂和抑制炎症，认为低密度脂蛋白会起到相反的作用。 Apoeh/hLdlr-/-Mx1-Cre小鼠血脂异常和动脉粥样硬化的快速逆转提供了强大的新的 解决与动脉硬化消退相关的机制的方法。因此，在目标2中，我们将测试 假设高血糖损害血管细胞的转录重编程，从而去除 动脉脂类的减少、巨噬细胞的外泄和胶原蛋白的积聚是对降脂的反应。 接下来，我们将探讨治疗性胰岛素治疗在促进动脉粥样硬化消退中的作用。 高血糖Apoeh/hLdlr-/-Mx1-Cre小鼠。 我们的长期目标是确定可以作为治疗靶点的机制，以延缓 糖尿病患者动脉粥样硬化的进展和加速消退作为PAD的治疗方法。

Summary of the research project proposed by Dr. Robert L. Raffai, PhD: 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.