Exploring the mechanisms of action of anti-ADAMTS 13 antibodies in immune thrombotic thrombocytopenic purpura

项目摘要/摘要 免疫性血栓性血小板减少性紫癜(ITTP)是一种由自身免疫引起的血栓性微血管病变 抑制酶ADAMTS13。ADAMTS13的唯一已知底物是von Willebrand因子(VWF)。 需要用ADAMTS13切割VWF，以防止超大VWF多聚体在 微血管形成，导致终末器官损害和潜在的危及生命的后果。抗ADAMTS13 免疫球蛋白负责该酶的抑制。绝大多数抑制性抗体针对的是 ADAMTS13，主要负责与被该酶切割的VWF结构域结合。然而， 抑制这些抗体的机制目前是一个活跃的研究领域，目前尚不清楚它们是否 主要是防止底物结合或降低催化周转率，或者如果不同的抗体抑制不同 机械装置。最近的研究表明，iTTP患者血浆中的ADAMTS13主要以构象形式存在 这暴露了一个隐秘的表位，否则当ADAMTS13处于潜伏状态时就会隐藏起来。当前的范例 ADAMTS13活动将其定义为所谓的“打开”状态，而将潜在状态定义为“关闭”状态。第三个州也是 似乎存在这样的情况，其中ADAMTS13曝光了神秘的插曲，但也能够切割VWF；这是 这里指的是“开放并准备好”状态。针对蛋白质远端结构域的抗ADAMTS13免疫球蛋白 看起来既能引起“开放”状态，又能引起“开放并准备好”状态。不同构象的作用 ADAMTS13在iTTP病理生理学中的作用尚不清楚，远端结构域靶向的潜在作用也不清楚 疾病中的伊戈斯。最后，还不知道ADAMTS13活动是否可以通过引入能够 竞争抗ADAMTS13免疫球蛋白与ADAMTS13的结合。本项目旨在阐明 抗ADAMTS13抗体的抑制机制(S)，表征远端结构域靶向抗ADAMTS13抗体的作用 ADAMTS13抗体在疾病的病理生理学中的作用，并探索分子模拟的结合 抗ADAMTS13免疫球蛋白表位作为疾病的抢救策略。我的职业目标是成为一名 作为内科科学家的独立研究员，专注于iTTP的病理生理学。我目前在 血液科内科助理教授终身教职轨迹 堪萨斯大学医学中心(KUMC)的大型学者，恶性肿瘤和细胞治疗学 中间。我的研究导师是世界知名的iTTP研究员X.龙正博士。我有80%的工资 根据我与大学的协议，我的研究时间受到保护。我的职业发展计划包括 定期与我的职业咨询委员会会面，接受结构生物学技术方面的实践培训 包括在这项提案中，以及持续的临床责任，包括每周半天的诊所，我在那里看到 非恶性血液病患者。

Project Summary/Abstract Immune thrombotic thrombocytopenic purpura (iTTP) is a thrombotic microangiopathy caused by autoimmune inhibition of the enzyme ADAMTS13. The only known substrate of ADAMTS13 is von Willebrand factor (VWF). Cleavage of VWF by ADAMTS13 is needed to prevent accumulation of ultralarge VWF multimers in the microvasculature, leading to end-organ damage and potentially life-threatening consequences. Anti-ADAMTS13 IgGs are responsible for the inhibition of the enzyme. The vast majority of inhibitory antibodies target a region of ADAMTS13 that is principally responsible for binding to the domain of VWF cleaved by the enzyme. However, the mechanism of inhibition of these antibodies is currently an area of active research, and it is not known if they primarily prevent substrate binding or decrease catalytic turnover, or if different antibodies inhibit by different mechanisms. Recent work has shown that ADAMTS13 in iTTP patient plasma exists primarily in a conformation that exposes a cryptic epitope otherwise hidden when ADAMTS13 is in its latent state. The current paradigm of ADAMTS13 activity defines this as a so-called “Open” state, and the latent state as “Closed”. A third state also appears to exist in which ADAMTS13 has the cryptic episode exposed, but also is able to cleave VWF; this is referred to here as the “Open and Primed” state. Anti-ADAMTS13 IgGs that target distal domains of the protein appear capable of inducing both the “Open” and “Open and Primed” state. The role of the different conformations of ADAMTS13 in the pathophysiology of iTTP is unclear, as is the potential role of the distal domain-targeting IgGs in the disease. Lastly, it is not known if ADAMTS13 activity can be rescued by introducing moieties capable of competing for the binding of anti-ADAMTS13 IgGs with ADAMTS13. This project aims to elucidate the mechanism(s) of inhibition of anti-ADAMTS13 antibodies, characterize the role of distal domain-targeting anti- ADAMTS13 antibodies in the pathophysiology of the disease, and explore molecular mimics of the binding epitopes of anti-ADAMTS13 IgGs as a rescue strategy for the disease. My career goal is to become an independent investigator as a physician scientist, with a focus on the pathophysiology of iTTP. I am currently on the tenure-track as an Assistant Professor in the Department of Internal Medicine, Division of Hematologic Malignancies and Cellular Therapeutics, at the University of Kansas Medical Center (KUMC), a large academic center. My research mentor is Dr. X. Long Zheng, a world-renowned researcher in iTTP. I am afforded 80% protected time for research under my agreement with the University. My career development plan includes regular meetings with my Career Advisory Committee, hands-on training in the structural biology techniques included in this proposal, and ongoing clinical responsibilities, including a half-day of clinic weekly where I see patients with non-malignant hematologic disorders.