Investigation of Beta2-glycoprotein I Complexes in Antiphospholipid Syndrome

描述(申请人提供)：抗磷脂综合征(APS)是一种自身免疫性疾病，临床特征为血栓形成和/或反复发生的胎儿丢失。β2-糖蛋白I(β2GPI)是APS相关抗体的主要抗原。只有抗2GPI抗体产生的二聚体形式的2GPI具有重要的病理意义，而单体2GPI在血浆中含量丰富。本研究的基本假设是2GPI/抗2GPI抗体复合物与脂蛋白受体和阴离子磷脂的相互作用是干预APS血栓形成的潜在药物靶点。我们在2GPI/抗2GPI抗体复合体中创建了一种二聚体抑制剂来选择性地靶向二聚体2GPI。该抑制剂破坏2GPI/抗体复合体与脂蛋白受体和阴离子磷脂的结合。这些研究将优化阻断2GPI/抗2GPI抗体复合物与脂蛋白受体和阴离子磷脂相互作用的抑制剂；利用该抑制剂、定点突变和细胞内和体内的功能研究来剖析脂蛋白受体和阴离子磷脂在APS血栓形成中的作用。这些研究将使用结构域相互作用的生物物理测量，蛋白质结构的核磁共振和结晶学测定，基于细胞的分析和激光诱导的活体小鼠血栓形成，以追求这些目标。

DESCRIPTION (provided by applicant): Antiphospholipid syndrome (APS) is an autoimmune disease characterized clinically by thrombosis and/or recurrent fetal loss. Beta2-glycoprotein I (¿2GPI) is the major antigen for the antibodies associated with APS. Only the dimeric form of 2GPI generated by anti-2GPI antibodies is pathologically important, in contrast to monomeric 2GPI which is abundant in plasma. The primary hypothesis of the proposed study is that the interaction of 2GPI/anti-2GPI antibody complexes with lipoprotein receptors and anionic phospholipid is a potential drug target for interfering with thrombosis in APS. We created a dimeric inhibitor to selectively target dimeric 2GPI in 2GPI/anti-2GPI antibody complexes. This inhibitor disrupts the binding of 2GPI/antibody complexes with lipoprotein receptors and anionic phospholipid. The proposed studies will optimize the inhibitor that blocks the interaction of 2GPI/anti-2GPI antibody complexes with lipoprotein receptors and anionic phospholipid; use the inhibitor, site-directed mutagenesis, and functional studies in cells and in vivo to dissect the contribution of lipoprotein receptors and anionic phospholipid to thrombosis in APS. The studies will employ biophysical measurements of domain interactions, NMR and crystallographic determination of protein structures, cell-based assays and laser-induced thrombosis in live mice in pursuit of these goals.