Re-evaluating the role of HDL in coronary artery disease (RETRO HDL)

 描述（由申请人提供）：与普通人群相比，1型糖尿病（T1 D）患者患冠状动脉疾病（CAD）的风险大大增加，尽管传统脂质和其他心血管风险因素仅存在微小差异。尽管T1 D患者的高密度脂蛋白胆固醇（HDL-C）水平普遍升高，但其仍能反向预测CAD风险。令人惊讶的是，对我们的糖尿病并发症流行病学（EDC）研究的18年随访分析显示，女性中HDL-C高度升高（>80 mg/dL）的CAD发病率增加，其中未注意到超过50 mg/dL的渐进性保护。在男性中，最初的强负相关关系在整个HDL-C水平范围内保持不变，尽管只有两个HDL-C高于80 mg/dL。因此，我们假设这些明显矛盾的发现，即高HDL-C存在时风险升高，反映了T1 D患者HDL功能受损。事实上，HDL-C功能障碍的假说在其最关键的活动，胆固醇逆向转运，长期以来一直提出在T1 D，虽然它还没有正式测试使用目前可用的新措施的HDL功能。 最近报道的结合珠蛋白（Hp）2等位基因与糖尿病CAD发病率之间的关联也被认为至少部分与这些个体中受损的HDL功能有关，即受损的胆固醇逆向转运。幽门螺杆菌是一种急性期血浆蛋白，其主要功能是结合游离血红蛋白，从而抑制血红素铁的释放，从而减少血红蛋白诱导的氧化性组织损伤。在T1 D中，我们发现Hp 2-2显著增加CAD风险，并且随着Hp 2等位基因的数量呈线性趋势增加风险。此外，在我们的HapE干预研究中，HDL介导的胆固醇流出与Hp 2等位基因的数量呈线性下降，而维生素E改善Hp 2-2携带者的胆固醇流出。 鉴于这些数据，我们的目的是使用新的复杂方法来确定：a）与非糖尿病对照相比，T1 D中HDL功能（固醇流出）是否受损（总体和按性别）; B）HDL功能预测T1 D中CAD的能力（按性别）;和c）HDL功能在多大程度上解释了所报道的T1 D中Hp- CAD关联。因此，我们提出使用充分验证的测定来量化巨噬细胞的HDL流出能力，并用HDL颗粒和HDL的蛋白质货物的浓度/大小的最新技术水平的量化来补充这些研究（提供关于HDL的抗炎和抗氧化性质的信息）。蛋白质组学分析，虽然本质上更具探索性，但将提供关于HDL的抗炎/抗氧化性质的数据，这将是非常令人感兴趣的，因为炎症/氧化应激在动脉粥样硬化发展中起作用，并且因为Hp是具有抗氧化性质的急性期蛋白。 因此，通过这项研究，我们的目标是进一步了解影响HDL对T1 D患者心脏保护作用的因素，并阐明性别差异以及该人群中与Hp 2等位基因相关的CAD风险增加的机制。

 DESCRIPTION (provided by applicant): Individuals with type 1 diabetes (T1D) are at greatly increased risk of coronary artery disease (CAD) compared to the general population, despite only minor differences in traditional lipid and other cardiovascular risk factors. Although generally elevated in T1D patients, high density lipoprotein cholesterol (HDL-C) levels still inversely predict CAD risk. Surprisingly, analyses of the 18-year follow-up of our Epidemiology of Diabetes Complications (EDC) study showed an increased CAD incidence with highly elevated (>80 mg/dL) HDL-C in women, in whom no progressive protection above 50 mg/dL was noted. In men, the original strong inverse relationship held throughout the range of HDL-C levels, though only two had HDL-C above 80 mg/dL. We therefore hypothesize that these apparently contradictory findings of elevated risk in the presence of high HDL- C reflect impaired HDL functionality in T1D. Indeed, the hypothesis of dysfunctional HDL-C in terms of its most critical activity, reverse cholesterol transport, has long been proposed in T1D, although it has not been formally tested using currently available novel measures of HDL function. The recently reported association between the Haptoglobin (Hp) 2 allele and CAD incidence in diabetes is also thought, at least partially, to relate to impaired HDL function, i.e. impaired reverse cholesterol transport, in these individuals. Hp is an acute phase plasma protein whose main function is to bind free hemoglobin, thereby inhibiting heme iron release and thus reducing hemoglobin-induced oxidative tissue damage. In T1D, we showed a significantly increased CAD risk with Hp 2-2 and a linear trend toward increased risk with the number of Hp 2 alleles. Additionally, in our HapE intervention study, HDL-mediated cholesterol efflux decreased linearly with the number of Hp 2 alleles, whereas vitamin E improved efflux among Hp 2-2 carriers. Given these data, our aim, using novel sophisticated methods, is to determine: a) whether HDL function (sterol efflux) is impaired in T1D compared to non-diabetic controls (overall and by gender); b) the ability of HDL function to predict CAD in T1D by gender; and c) to what extent HDL function explains the reported Hp- CAD association in T1D. We thus propose to quantify HDL efflux capacity with macrophages using a well- validated assay, and complement these studies with state-of-the art quantification of the concentration/size of HDL particles and HDL's protein cargo (providing information on HDL's anti-inflammatory and anti-oxidative properties). The proteomic analyses, though more exploratory in nature, will provide data on HDL's anti- inflammatory/anti-oxidative properties, which would be of great interest as inflammation/oxidative stress play a role in atherosclerosis development and as Hp is an acute phase protein with anti-oxidative properties. With this research we therefore aim to further our understanding of factors that influence HDL's cardioprotective effects in patients with T1D and shed light on gender differences as well as the mechanisms underlying the increased CAD risk associated with the Hp 2 allele in this population.