Proteolysis of ultralarge von Willebrand factor and metabolic syndrome-diabetes

描述（由申请人提供）：代谢综合征-糖尿病代表一组动脉粥样硬化血栓形成的高风险（肥胖、血脂异常、高血压、胰岛素抵抗），并以慢性和全身性炎症为特征，最终演变为动脉粥样硬化和血栓形成。该疾病的一个标志性早期事件是内皮损伤，内皮损伤表达和释放粘附分子，其中包括血管性血液病因子（VWF）。VWF是应用最广泛的内皮损伤标志物，但其粘附特性及其在动脉粥样硬化血栓形成过程中的作用研究较少。尽管研究发现缺乏VWF的小鼠发生较少的动脉粥样硬化病变。我们最近发现，在患有严重全身性炎症的患者中，ADAMTS-13的活性下降，ADAMTS-13可以切割ULVWF以降低其粘连性。在高胆固醇血症小鼠中也观察到这种降低。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，由于炎症内皮细胞持续释放ULVWF和抑制ADAMTS-13的合成和活性，代谢综合征中ULVWF蛋白水解不足或不足。因此，内皮细胞上未或部分裂解的ULVWF系住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粘附特性来衡量代谢综合征中ULVWF蛋白水解是否不足？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，是什么导致了维生素缺乏症？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、高胆固醇血症和糖尿病的小鼠注射重组ADAMTS-13。提出的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形成并发症（和全身性炎症）的病理生理学。它们也将为治疗和预防这种疾病提供新的治疗靶点。

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.