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Antiphospholipid-mediated endothelium perturbation plays a role in antiphospholipid syndrome (APS)-associated vasculopathy. Antiphospholipid antibodies activate endothelium both in vitro and in vivo experimental models by inducing a pro-inflammatory/-coagulant phenotype; the antibodies recognize h2 glycoprotein I (h2GPI) on human endothelial cells (EC) from different parts of the vasculature.In spite of such large in vitro evidence, few studies have addressed the issue whether or not a comparable endothelial perturbation might be detectable in vivo.We investigated several indirect ex vivo parameters of endothelial dysfunction: plasma levels of soluble adhesion molecules (sADM), soluble thrombomodulin (sTM), von Willebrand factor (vWF) and tissue plasminogen activator (t-PA) by solid-phase assays. The study included: patients with primary antiphospholipid syndrome (n=32), with the syndrome secondary to non-active systemic lupus erythematosus (SLE, n=10), six patients with persistent antiphospholipid positivity at medium/high titre without any clinical manifestation of the syndrome. Fifty-two age and sex matched healthy subjects have been enrolled as controls. In addition, circulating endothelial cells identified by flow cytometry and the brachial artery flow-mediated vasodilation (FMV) were evaluated in 26 patients (20 primary and 6 lupus syndromes) and 30 healthy controls.

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Starting from their first description, antiphospholipid antibodies (aPL) were associated with repeated miscarriages and fetal losses. Other complications of pregnancy like preterm birth,with pre-eclampsia or severe placental insufficiency were also frequently reported and are included in the current classification criteria of the antiphospholipid syndrome (APS). The titre, the isotype of the antibodies or their antigen specificity may be important in the risk level determination. Some of the difference in the reported results can be explained by the poor standardization achieved in aPL testing or by the not univocal classification of pregnancy complications. The pathogenesis of pregnancy failures is linked to the thrombophilic effect of aPL but also to different mechanisms including a direct effect of antibodies on the throphoblast differentiation and invasion. The study of experimental animal models provided sound evidence of the pathogenic role of aPL both in lupus prone and naive mice. The definition of APS as a condition linked to high obstetric risk and the application of an effective therapy have completely changed the prognosis of pregnancy in these patients. In fact, despite the high number of complications and preterm delivery, today a successful outcome can be achieved in the large majority of the cases.