Oxysterols, Estrogen Receptor Antagonism, and Vascular Disease

描述（由申请人提供）：雌激素有可能提供有效的心血管保护。然而，有一些机制可以改变雌激素的血管作用，特别是如果疾病已经存在。在目前的资助期间，我们确定了27-羟基胆固醇（27 HC），这是升高与高胆固醇血症，作为第一个内源性选择性雌激素受体调节剂（SERM）。我们发现，27 HC拮抗内皮和血管平滑肌（VSM）中的雌激素受体（ER）功能，并导致E2诱导的小鼠再内皮化受损。最近对代谢27 HC的Cyp 7 b1无效小鼠的初步研究表明，27 HC也可能促进动脉粥样硬化形成，减弱E2诱导的新生内膜形成保护，并损害E2对体重的调节。后一个发现也可能表明葡萄糖稳态受损。我们的总体目标是现在确定27 HC如何直接和间接地促进血管疾病的发病机制，以及如何改变27 HC水平和作用以减轻血管疾病。目的1是确定27 HC给药如何影响血管疾病的发病机制。将在apoE+/+ vs. apoE-/-雄性和卵巢切除安慰剂vs. E2处理雌性小鼠中评价27 HC诱导的动脉粥样硬化病变丰度和特征的变化。我们还将确定27 HC如何影响E2介导的内膜增生保护，并将在培养中研究27 HC对E2调节巨噬细胞和VSM细胞功能的影响。目的2是确定27 HC如何影响体重调节和葡萄糖稳态，这是影响心血管健康的第二个因素。将在对照组与27 HC处理的卵巢切除安慰剂组与E2处理的雌性C57 BL/6小鼠中定量食物摄入、能量消耗和肥胖，所述雌性C57 BL/6小鼠置于对照组与西方饮食组。将对葡萄糖耐量和胰岛素敏感性以及决定它们的机制进行评价。将通过27 HC的脑室内递送来区分27 HC对ER代谢调节的CNS与外周作用。目的3是确定如何预防高胆固醇血症发生的27 HC升高影响E2对动脉粥样硬化和代谢的保护作用。通过静脉注射编码Cyp 7 b1的腺病毒使Cyp 7 b1在肝脏过表达，以及通过产生肝脏特异性Cyp 7 b1转基因小鼠，血清27 HC将降低。目的4是开发新的策略来减弱血清27 HC水平和27 HC在靶细胞中的作用。使用一种新的双核SERM，我们开发了在小鼠体内使用，非核ER信号在肝Cyp 7 b1上调E2细胞培养研究中提出的作用将在体内划定。使用通过噬菌体展示鉴定的肽独特地结合到27 HC配体的ER，将在培养的细胞中追求用于选择性阻断由核以及非核ER介导的27 HC作用的方法。通过实现这些目标，我们将增加我们对血管健康和疾病背景下唯一已知的内源性SERM生物学的基本理解。 公共卫生相关性：27-羟基胆固醇是胆固醇的代谢物，当循环胆固醇水平高时，其在血液中升高，并且其在患病动脉中与胆固醇一起积累。我们已经发现，27-羟基胆固醇在许多细胞类型和器官中改变雌激素的作用。拟议的研究计划将确定27-羟基胆固醇如何通过其对雌激素作用的影响促进血管疾病的发展以及体重和葡萄糖调节受损。

DESCRIPTION (provided by applicant): Estrogen has the potential to provide potent cardiovascular protection. However, there are mechanisms that modify the vascular actions of estrogen, particularly if disease is already present. In the current funding period we identified 27-hydroxycholesterol (27HC), which is elevated with hypercholesterolemia, as the first endogenous selective estrogen receptor modulator (SERM). We showed that 27HC antagonizes estrogen receptor (ER) function in endothelium and vascular smooth muscle (VSM), and that it causes impaired E2- induced reendothelialization in mice. Recent preliminary studies in mice null for Cyp7b1, which metabolizes 27HC, suggest that 27HC may also promote atherogenesis, attenuate E2-induced protection from neointima formation, and impair E2 regulation of body weight. The latter finding is also likely indicative of impaired glucose homeostasis. Our Overall Objective is to now determine how 27HC contributes directly and indirectly to vascular disease pathogenesis, and how 27HC levels and actions can be modified to lessen vascular disease. Aim 1 is to determine how administered 27HC impacts vascular disease pathogenesis. 27HC-induced changes in atherosclerotic lesion abundance and characteristics will be evaluated in apoE+/+ vs. apoE-/- male and ovariectomized placebo vs. E2-treated female mice. We will also determine how 27HC impacts E2-mediated protection from intimal hyperplasia, and effects of 27HC on E2 regulation of macrophage and VSM cell function will be investigated in culture. Aim 2 is to determine how 27HC impacts body weight regulation and glucose homeostasis, which secondarily influence cardiovascular health. Food intake, energy expenditure and adiposity will be quantified in control vs. 27HC-treated ovariectomized placebo vs. E2-treated female C57BL/6 mice placed on control vs. Western diet. Glucose tolerance and insulin sensitivity and the mechanisms that determine them will be evaluated. CNS vs. peripheral actions of 27HC on ER regulation of metabolism will be distinguished by intraventricular delivery of 27HC. Aim 3 is to determine how prevention of the elevation in 27HC that occurs with hypercholesterolemia impacts the protective actions of E2 on atherosclerosis and metabolism. Serum 27HC will be lowered by hepatic overexpression of Cyp7b1 by IV injection of adenovirus encoding the enzyme and also by creation of a liver-specific Cyp7b1 transgenic mouse. Aim 4 is to develop new strategies to attenuate serum 27HC levels and 27HC actions in target cells. Using a novel extranuclear SERM we developed for in vivo use in mice, the role of non-nuclear ER signaling in hepatic Cyp7b1 upregulation by E2 suggested in cell culture studies will be delineated in vivo. Using peptides identified by phage display to uniquely bind to 27HC-liganded ER, approaches for the selective blockade of 27HC actions mediated by nuclear as well as non-nuclear ER will be pursued in cultured cells. By accomplishing these aims, we will increase our basic understanding of the biology of the only known endogenous SERM in the context of vascular health and disease. PUBLIC HEALTH RELEVANCE: 27-hydroxycholesterol is a metabolite of cholesterol that is elevated in the blood when circulating cholesterol levels are high, and it accumulates with cholesterol in diseased arteries. We have discovered that 27-hydroxycholesterol modifies the actions of estrogen in numerous cell types and organs. The proposed research program will determine how 27-hydroxycholesterol, through its impact on estrogen action, contributes to the development of blood vessel disease and to impaired body weight and glucose regulation.