Abstract 13186: Development of Novel, Mechanism-Based Therapies to Prevent the Cardiovascular Complications of the Antiphospholipid Syndrome
Patients with antiphospholipid syndrome (APS) have circulating antiphospholipid antibodies (aPL) and increased risk of thrombosis as well as non-thrombotic vascular disease. Current APS treatment is limited to anticoagulation, which targets only a portion of APS-related disease and has modest efficacy and serious potential complications. We previously showed that aPL antagonism of endothelial NO synthase (eNOS) underlies APS-associated thrombosis. Seeking to develop therapies directed at the initiating processes for both APS-related thrombosis and non-thrombotic vascular disease, we studied the basis for eNOS antagonism by aPL and also determined how aPL impact endothelial repair. In scratch assays with bovine aortic endothelial cells (BAEC), we found that in contrast to IgG from normal healthy subjects (NHIgG) which had no effect, polyclonal aPL from APS patients inhibited migration stimulated by VEGF. The migratory response was restored by the NO donor S-nitroso-N-acetylpenicillamine, a monoclonal antibody (mAb) to the cell surface protein β2GPI had effects identical to aPL, and aPL antagonism of migration was prevented by siRNA knockdown of apolipoprotein E receptor 2 (apoER2). Thus, the β2GPI/apoER2-mediated eNOS antagonism that we previously discovered underlies aPL-induced thrombosis also antagonizes endothelial cell migration. Mimicking the cell culture findings, in C57BL/6 male mice carotid artery reendothelialization was attenuated by aPL treatment, and this was fully prevented by the NO donor molsidomine. We then screened a series of mAb to β2GPI in assays of eNOS activation in BAEC. Whereas many mirrored aPL and antagonized eNOS, one anti-β2GPI mAb designated 1N11 had no effect when tested alone and it fully prevented aPL action. 1N11 also prevented aPL inhibition of endothelial cell migration, and it rescued normal carotid artery reendothelialization in aPL-treated mice. Thus, by bypassing or disrupting how aPL antagonize eNOS, an NO donor or a select mAb to β2GPI can afford protection from the endothelial actions of aPL that underlie the vascular manifestations of APS. Such mechanism-based therapies offer the promise of greater efficacy and fewer complications in patients with this often life-threatening disorder.
- © 2012 by American Heart Association, Inc.