Anticardiolipin Antibodies and Oxidized Phospholipids

抗磷脂抗体综合征(APS)患者具有对某些磷脂(APL)的自身抗体，如心磷脂和/或狼疮抗凝剂，临床上有反复静脉或动脉血栓形成、胎儿死亡和自身免疫性血小板减少的病史。在其他健康的男性中，APL的增加似乎也预示着中风和心肌梗死风险的增加。然而，关于APL的靶抗原存在争议，甚至大学实验室也无法就谁的APL滴度升高达成一致。反过来，由于缺乏潜在的假设来解释为什么应该对PL这样普遍存在的化合物形成抗体，临床管理受到了阻碍。我们提出了一个新的假设，即许多APL针对氧化磷脂(OxPL)的表位和/或OxPL与相关PL结合蛋白的共价加合物，如Beta2GPI。我们的假设认为，炎症或动脉粥样硬化中发生的脂质过氧化状态会导致PL的氧化(如在低密度脂蛋白中或在凋亡或濒临死亡的细胞膜中)，从而产生新的自主决定因素和免疫原性表位。然后，产生的自身抗体可以针对许多组织中的这些新表位，并可能产生各种生物学后果。心磷脂(CL)是检测APL最常用的PL。我们已经证明，APS血浆与OxCL或OxCL与Beta2GPI的加合物特异结合，而不与天然CL结合。我们建议通过确定其他OxPL抗体是否也存在于狼疮样综合征患者和小鼠的血清中来进一步验证我们的假设。我们将从(NZWxBXSB)F1雄性小鼠中产生一组这样的OxPL小鼠单克隆。类似的Fab和ScFv抗体将从人噬菌体展示文库中产生。我们将确定它们结合的表位及其对体外和体内凝血的影响，重点是蛋白C途径。我们将用有效的抗氧化剂治疗易患狼疮的小鼠，看看APL滴度和/或其他临床参数是否发生变化。了解一些APL的病因不仅应该导致开发更标准化的检测方法，这将提高我们检测高危个体的能力，而且还应该考虑APL和APS患者的新治疗方式(例如，积极的抗炎和/或抗氧化干预)。

Patients with the antiphospholipid antibody syndrome (APS) have autoantibodies to certain phospholipids (aPL) such as cardiolipin and/or the lupus anticoagulant and clinically experience recurrent venous or arterial thrombosis, history of fetal death and autoimmune thrombocytopenia. Increased aPL also appear to predict increased risk of stroke and myocardial infarction in otherwise healthy men as well. However, controversy exists about the target antigens of aPL, and even university laboratories cannot agree who has elevated aPL titers. In turn, clinical management is hampered by lack of an underlying hypothesis to explain why antibodies should form to such ubiquitous compounds as PL. We have developed the novel hypothesis that many aPL are directed against epitopes of oxidized PL (OxPL) and/or against covalent adducts of OxPL and associated PL binding proteins, such as beta2GPI. Our hypothesis suggests that states of enhanced lipid peroxidation, as occurs in inflammation or atherosclerosis, leads to oxidation of PL (such as in LDL or in membranes of apoptotic or dying cells) which creates neo self-determinants and immunogenic epitopes. The resultant autoantibodies can then target such neoepitopes in many tissues, and may have a variety of biological consequences. Cardiolipin (CL) is the most common PL used to test for aPL. We have shown that APS plasma bind exclusively to OxCL, or to OxCL adducts with beta2GPI, and not to native CL. We propose to further test our hypothesis by determining if antibodies to other OxPL are also present in sera from patients and mice with lupus- like syndromes. We will generate a panel of such aOxPL murine monoclonals from (NZWxBXSB) F1 males. Similar Fab and scFv antibodies will be generated from a human phage-display library. We will determine the epitopes to which they bind and their impact on in vitro and in vivo coagulation, with an emphasis on the Protein C pathway. We will treat lupus-prone mice with potent antioxidants to see if changes in aPL titers and/or other clinical parameters occur. Understanding the etiology of even some of the aPL should lead not only to development of more standardized assays, which should improve our ability to detect high risk individuals, but also to consideration of new therapeutic modalities for patients with aPL and APS (e.g. aggressive anti-inflammatory and/or antioxidant interventions).