Dong Jing-fei, Moake Joel L, Nolasco Leticia, Bernardo Aubrey, Arceneaux Wendy, Shrimpton Corie N, Schade Alicia J, McIntire Larry V, Fujikawa Kazuo, López José A
Thrombosis Research Section, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
Blood. 2002 Dec 1;100(12):4033-9. doi: 10.1182/blood-2002-05-1401. Epub 2002 Jul 25.
Thrombotic thrombocytopenic purpura (TTP) is a devastating thrombotic disorder caused by widespread microvascular thrombi composed of platelets and von Willebrand factor (VWF). The disorder is associated with a deficiency of the VWF-cleaving metalloprotease, ADAMTS-13, with consequent accumulation of ultralarge (UL) VWF multimers in the plasma. ULVWF multimers, unlike plasma forms of VWF, attach spontaneously to platelet GP Ibalpha, a component of the GP Ib-IX-V complex. We have found that ULVWF multimers secreted from stimulated endothelial cells (ECs) remained anchored to the endothelial surface where platelets and Chinese hamster ovary cells expressing the GP Ib-IX-V complex attached to form long beads-on-a-string structures in the presence of fluid shear stresses in both the venous (2.5 dyne/cm(2)) and arterial (20 and 50 dyne/cm(2)) ranges. Although measurement of the activity of the ADAMTS-13 VWF-cleaving metalloprotease in vitro requires prolonged incubation of the enzyme with VWF under nonphysiologic conditions, EC-derived ULVWF strings with attached platelets were cleaved within seconds to minutes in the presence of normal plasma (containing approximately 100% ADAMTS-13 activity) or in the presence of partially purified ADAMTS-13. By contrast, the strings persisted for the entire period of perfusion (10 minutes) in the presence of plasma from patients with TTP containing 0% to 10% ADAMTS-13 activity. These results suggest that cleavage of EC-derived ULVWF multimers by ADAMTS-13 is a rapid physiologic process that occurs on endothelial cell surfaces.
血栓性血小板减少性紫癜（TTP）是一种由血小板和血管性血友病因子（VWF）组成的广泛微血管血栓引起的毁灭性血栓性疾病。该疾病与VWF裂解金属蛋白酶ADAMTS - 13缺乏有关，导致血浆中超大（UL）VWF多聚体积累。与血浆形式的VWF不同，ULVWF多聚体可自发附着于血小板糖蛋白Ibalpha，后者是糖蛋白Ib - IX - V复合物的一个组成部分。我们发现，受刺激的内皮细胞（ECs）分泌的ULVWF多聚体仍锚定在内皮表面，在静脉（2.5达因/平方厘米）和动脉（20和50达因/平方厘米）范围内的流体剪切应力作用下，表达糖蛋白Ib - IX - V复合物的血小板和中国仓鼠卵巢细胞附着在其上形成长的串珠状结构。尽管在体外测量ADAMTS - 13 VWF裂解金属蛋白酶的活性需要在非生理条件下将该酶与VWF长时间孵育，但在正常血浆（含有约100% ADAMTS - 13活性）或部分纯化的ADAMTS - 13存在的情况下，附着有血小板的EC衍生的ULVWF串在数秒至数分钟内被裂解。相比之下，在含有0%至10% ADAMTS - 13活性的TTP患者血浆存在的情况下，这些串在整个灌注期间（10分钟）都持续存在。这些结果表明，ADAMTS - 13对EC衍生的ULVWF多聚体的裂解是一个在内皮细胞表面发生的快速生理过程。
