Proteolysis of ultralarge von Willebrand factor and metabolic syndrome-diabetes

描述（申请人提供）：代谢综合征-糖尿病代表动脉粥样硬化血栓形成的一组高风险（肥胖、血脂异常、高血压、胰岛素抵抗），其特征为慢性全身性炎症，最终演变为动脉粥样硬化和血栓形成。该疾病的标志性早期事件是表达和释放粘附分子的内皮损伤，其中包括血管性血友病因子（VWF）。VWF是内皮损伤最广泛使用的标志物，但对其粘附特性以及在动脉粥样硬化血栓形成的起始和传播中的作用的研究较少。尽管发现缺乏VWF的小鼠发生较少的动脉粥样硬化病变。我们最近发现，ADAMTS-13的活性，它切割ULVWF，以减少其炎症，在严重的全身性炎症患者降低。在患有高胆固醇血症的小鼠中也观察到这种降低。我们进一步发现ADAMTS-13的合成在糖尿病小鼠的肝脏中严重减少。这些初步结果和已发表的数据使我们假设，由于发炎的内皮细胞持续释放ULVWF和抑制ADAMTS-13的合成和活性，在代谢综合征中ULVWF蛋白水解是缺乏或不足的。因此，内皮细胞上未裂解或部分裂解的ULVWF束缚并聚集血小板和白细胞，从而促进内皮损伤和动脉粥样硬化血栓形成。我们建议通过临床、动物和体外研究来验证这一假设，以回答四个具体问题。首先，通过ADAMTS-13活性和血浆VWF的粘附特性来衡量，在代谢综合征中ULVWF蛋白水解缺陷吗？第二，这种缺乏是否与动脉粥样硬化病变的发生和发展有关？第三，是什么原因造成的缺陷？我们将特别关注炎症性脂肪因子、可溶性VWF、脂质、葡萄糖和胰岛素对ADAMTS-13合成和活性的影响。第四，重组ADAMTS-13能否减轻或延缓血管损伤和动脉粥样硬化病变？为此，我们将定期向患有肥胖症、高胆固醇血症和糖尿病的小鼠施用重组ADAMTS-13。这些研究将有助于我们了解代谢综合征-糖尿病及其常见的动脉粥样硬化血栓并发症（和全身炎症）的病理生理学。同时也为该病的防治提供了新的治疗靶点。 项目叙述：本项目旨在研究在代谢综合征-糖尿病的条件下，ULVWF的蛋白水解如何变得缺乏。它将调查ADAMTS-13的合成和活动的代谢综合征-糖尿病患者的病理生理变化，在小鼠轴承组件的这种综合征，并在一组体外实验。该研究的结果将帮助我们了解缺陷的ULVWF蛋白水解如何促进与该综合征相关的动脉粥样硬化血栓形成的发展。

DESCRIPTION (provided by applicant): Metabolic syndrome-diabetes represents a cluster of high risks for atherothrombosis (obesity, dyslipidemia, hypertension, insulin resistance) and is characterized by chronic and systemic inflammation that evolves eventually to atherosclerosis and thrombosis. A hallmark early event for the disease is endothelial injury that expresses and releases adhesion molecules, among them von Willebrand factor (VWF). VWF is the most widely used marker for endothelial injury, but much less studied for its adhesive properties and roles in the initiating and propagating atherothrombosis. This is despite the findings that mice deficient in VWF develop less atherosclerotic lesions. We have recently found that the activity of ADAMTS-13, which cleaves ULVWF to reduce its adhesiveness, is decreased in patients with severe systemic inflammation. The decrease is also observed in mice with hypercholesterolemia. We further find that ADAMTS-13 synthesis is severely reduced in the liver of diabetic mice. These preliminary results and published data have led us to hypothesize that ULVWF proteolysis is deficient or insufficient in metabolic syndrome due to persistent ULVWF release by inflamed endothelial cells and inhibition of ADAMTS-13 synthesis and activity. As a result, un- or partially cleaved ULVWF on endothelial cells tether and aggregate platelets and leukocytes that promotes endothelial injury and atherothrombosis. We proposed to test this hypothesis by clinical, animal, and in vitro studies to answer four specific questions. First, is ULVWF proteolysis deficient in metabolic syndrome as measure by ADAMTS-13 activity and the adhesive properties of plasma VWF? Second, does the deficiency correlate with the initiation and propagation of atherosclerotic lesions? Third, what causes the deficiency? We will specifically focus on the effects of inflammatory adipokines, soluble VWF, lipids, glucose, and insulin on ADAMTS-13 synthesis and activity. Fourth, can recombinant ADAMTS-13 reduce or delay the vascular injury and atherosclerotic lesions? For this, we will periodically administer recombinant ADAMTS-13 to mice that suffer obesity, hypercholesterolemia, and diabetes. The proposed studies will help us to understand the pathophysiology of metabolic syndrome-diabetes and its common atherothrombostic complications (and systemic inflammation). They will also provide new therapeutic target to treat and prevent the disease. PROJECT NARRATIVE: This is project is designed to study how proteolysis of ULVWF becomes deficient in conditions of metabolic syndrome-diabetes. It will investigate pathophysiological changes in ADAMTS-13 synthesis and activity in patients with metabolic syndrome- diabetes, in mice bearing components of this syndrome, and in a set of in vitro experiments. Results of the study will help us to understand how defective ULVWF proteolysis contributes to the development of atherothrombosis associated with the syndrome.