Project 4: Lipoproteins and CVD risk in diabetes

我们的研究计划旨在通过增加动脉粥样硬化的水平来确定促进动脉粥样硬化形成的可改变因素 导致动脉粥样硬化的脂蛋白和/或通过损害高密度脂蛋白从动脉壁巨噬细胞中去除胆固醇的能力。 与大多数研究人员不同，我们首先确定了预测心血管疾病的蛋白质和脂蛋白 然后根据这些结果在小鼠身上进行机制研究。一位少校 这种方法的组成部分是设计高通量的最先进的分析方法，用于 临床研究。我们对糖尿病动脉粥样硬化性疾病特别感兴趣，因为没有- 1型糖尿病患者(T1 DM)和2型糖尿病患者已确定的脂蛋白危险因素 (T2 DM)使用他汀类药物治疗仍然有很大的心血管疾病风险。 我们令人信服的初步数据表明，被糖尿病环境改变的小高密度脂蛋白颗粒强烈地预测 健康T1 DM患者的未来心血管事件(n=181，P=0.0008)。同时，我们从19例T2 DM患者中分离出高密度脂蛋白 受试者和20名对照组，并显示小高密度脂蛋白的胆固醇流出能力一个建议的指标 在高密度脂蛋白的心脏保护作用中，在T2 DM受试者中明显受损。这些观察结果表明 对T1 DM和T2 DM患者高密度脂蛋白的两个特定缺陷--大小和无法清除胆固醇 来自动脉壁--这可能会增加心血管疾病的风险。小的高密度脂蛋白颗粒明显 随后经历心血管事件的健康T1糖尿病患者的升高与这种高水平的教条相矛盾 高密度脂蛋白的水平总是对心脏有保护作用。这项提议的一个主要目标是确定 小高密度脂蛋白与心血管疾病的关系。首先，我们建议确认和扩大我们的发现在 两项针对T1和T2 DM受试者的大型临床研究。我们还计划探索脂肪分解的假说 富含甘油三酯的脂蛋白将高度致动脉粥样硬化的残余脂蛋白(RLP)的产生与 将高密度脂蛋白重塑为功能失调的小颗粒。第二，我们将使用一只表达人载脂蛋白A1的小鼠， 高密度脂蛋白的主要蛋白，以检测磷脂转移蛋白(PLTP)在RLP形成中的作用和小分子 糖尿病小鼠体内的高密度脂蛋白颗粒。我们基于PLTP推动了 在小鼠体内，无论是小的还是大的高密度脂蛋白颗粒，PLTP都能增加肝脏VLDL的产生(VLDL的前身 RLP)，而PLTP在孟德尔随机研究中与心血管疾病风险增加相一致 高密度脂蛋白-胆固醇水平升高，小高密度脂蛋白比例增加。重要的是，PLTP还预测了 我们对T1 DM患者的心血管事件研究。总而言之，我们提议的实验将提供一个强大的测试 假设高水平的小的、功能失调的高密度脂蛋白是高血压的标志，或者可能是调停物 糖尿病患者心血管疾病风险增加。

Our research program aims to identify modifiable factors that promote atherogenesis by increasing levels of atherogenic lipoproteins and/or by impairing HDL’s ability to remove cholesterol from artery wall macrophages. In contrast to most investigators, we first identify proteins and lipoproteins that predict cardiovascular disease risk (CVD) risk in humans and then perform mechanistic studies in mice based on those results. A major component of this approach has been to devise high-throughput state-of-the-art analytical methods for use in clinical studies. We have a particular interest in diabetic atherosclerotic disease because there are no well- established lipoprotein risk factors in type 1 diabetic patients (T1DM) and because type 2 diabetic patients (T2DM) treated with statins still have a substantial risk for CVD. Our compelling preliminary data suggest that small HDL particles altered by the diabetic milieu strongly predict future CVD events in healthy T1DM patients (n=181, P=0.0008). In parallel, we isolated HDL from 19 T2DM subjects and 20 control subjects and showed that small HDL’s cholesterol efflux capacitya proposed metric of HDL’s cardioprotective effectswas markedly impaired in the T2DM subjects. These observations point to two specific defects in HDL of T1DM and T2DM patients—size and inability to remove cholesterol from the artery wall—that may increase CVD risk. The demonstration that small HDL particles are markedly elevated in healthy T1DM patients who subsequently experience CVD events contradicts the dogma that high levels of HDL are always cardioprotective. A major goal of this proposal is to identify the mechanisms underlying the association of small HDL with CVD. First, we propose to confirm and extend our findings in two large clinical studies of T1DM and T2DM subjects. We also plan to explore the hypothesis that lipolysis of triglyceride-rich lipoproteins couples the generation of highly atherogenic remnant lipoproteins (RLPs) with remodeling of HDL into small, dysfunctional particles. Second, we will use a mouse expressing human APOA1, HDL’s major protein, to test the role of phospholipid transfer protein (PLTP) in the formation of RLPs and small HDL particles in diabetic mice. We base this approach on the demonstration that PLTP drives the generation of both small and large HDL particles in mice, that PLTP increases hepatic production of VLDL (the precursor of RLPs), and that PLTP associates in Mendelian randomization studies with increased CVD risk in concert with increased HDL-cholesterol levels and a larger percentage of small HDL. Importantly, PLTP also predicted incident CVD in our study of T1DM patients. Collectively, our proposed experiments will provide a powerful test of the hypothesis that a high level of small, dysfunctional HDL is a marker, and perhaps a mediator, of increased CVD risk in patients with diabetes.