Background
Antiphospholipid syndrome (APS) is characterized by recurrent thromboembolic events in the setting of pathologic autoantibodies, some of which are directed to β2-Glycoprotein 1 (β2GPI). The mechanisms of thrombosis in APS appear to be multifactorial and likely include a component of endothelial activation. Among other things, activated endothelium secretes von Willebrand factor, a hemostatic protein that in excess can increase the risk of thrombosis.
Conclusions
These results suggest that VWF and ADAMTS13 may play a role in the prothrombotic phenotype of APS.
Methods
Isolated anti-β2GPI antibodies from patients with APS were assayed for their ability to induced VWF release from HUVECs and modulate the effects of ADAMTS13 in a shear-dependent assay.
Objective
We hypothesized that anti-β2GPI antibodies could regulate the release and modulation of VWF from endothelial cells. Patients/
Results
We observed that anti-β2GPI antibodies from some patients with APS induced VWF release from human endothelial cells but did not induce formation of cell-anchored VWF-platelet strings. Finally, we also determined that one of the Anti-β2GPI antibodies tested can inhibit the function of ADAMTS13, the main modulator of extracellular VWF. Conclusions: These results suggest that VWF and ADAMTS13 may play a role in the prothrombotic phenotype of APS.