Proteolysis of ultralarge von Willebrand factor and metabolic syndrome-diabetes

描述(申请人提供)：代谢综合征-糖尿病是动脉粥样硬化血栓形成(肥胖、血脂异常、高血压、胰岛素抵抗)的一组高风险，其特征是慢性和系统性炎症，最终演变为动脉粥样硬化和血栓形成。该病早期的一个标志性事件是表达和释放黏附分子的内皮损伤，其中包括von Willebrand因子(VWF)。VWF是血管内皮细胞损伤的最广泛的标志物，但对其黏附特性及其在动脉粥样硬化形成和传播中的作用的研究较少。尽管有研究发现，缺乏VWF的小鼠较少出现动脉粥样硬化病变。我们最近发现，在患有严重全身炎症的患者中，ADAMTS-13的活性降低，这种活性可以切割ULVWF以降低其粘附性。在高胆固醇血症的小鼠身上也观察到了这种下降。我们进一步发现，糖尿病小鼠肝脏中ADAMTS-13的合成严重减少。这些初步结果和已发表的数据使我们假设，在代谢综合征中，由于炎症的内皮细胞持续释放ULVWF并抑制ADAMTS-13的合成和活性，ULVWF的蛋白降解不足或不足。因此，未切割或部分切割内皮细胞上的ULVWF将促进内皮细胞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，以回答四个具体的问题。首先，通过ADAMTS-13活性和血浆VWF的黏附特性来衡量代谢综合征中的ULVWF蛋白降解是否存在缺陷？第二，这种缺陷是否与动脉粥样硬化病变的启动和扩散有关？第三，造成这一缺陷的原因是什么？我们将特别关注炎性脂肪因子、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，我们将定期给患有肥胖症、高胆固醇血症和糖尿病的小鼠服用重组ADAMTS-13。建议的研究将帮助我们了解代谢综合征-糖尿病及其常见的动脉粥样硬化性血栓并发症(和全身炎症)的病理生理学。它们还将为治疗和预防这种疾病提供新的治疗靶点。 项目简介：该项目旨在研究ULVWF的蛋白分解如何在代谢综合征-糖尿病的条件下变得缺乏。它将研究代谢综合征-糖尿病患者、携带该综合征组成部分的小鼠的ADAMTS-13合成和活性的病理生理变化，并进行一系列体外实验。这项研究的结果将有助于我们了解ULVWF蛋白降解缺陷如何促进与该综合征相关的动脉粥样硬化血栓的发展。

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.