In an experimental model, the investigators demonstrated that passive transfer of human aPL to mice induced a marked endothelial dysfunction assessed ex vivo in small resistance arteries, and an increase in TNFα levels. Moreover, the investigators group have demonstrated that patients with primary arterial APS display endothelial dysfunction and structural arterial changes, associated with a pro-oxidative and pro-coagulant state and with activation of the TLR2 and TLR4 signalling pathways.