Adverse Pregnancy Outcome in Antiphospholipid Antibodies Syndrome: Pathogenic Mechanisms and Clinical Management

Abstract

The term antiphospholipid antibodies syndrome (APS) defines an autoantibody induced thrombophilia, associated to recurrent thrombosis and pregnancy complications (Hughes, 1993). Diagnosis of APS requires both serological positivity for antiphospholipid antibodies (aPL), a heterogeneous family of autoantibodies directed against protein phospholipid complexes, and the onset of the diagnostic clinical manifestations (see more below). Indeed, it has been widely shown that aPL are not sufficient per se to determine clinical manifestations of APS and that the likelihood that aPL may contribute to the pathogenesis of thrombosis or pregnancy complications, or both, varies between clinical settings (Meroni et al., 2004). To better define this complex syndrome, it must clarify that APS is commonly distinguished between “primary APS”, not associated to other autoimmune diseases, and “secondary APS”, when aPL serological positivity and clinical features of APS occur in the context of a known autoimmune disease. The majority of patients with secondary APS are affected from Systemic Lupus Erythematosus (SLE) and develop aPL serological positivity. About 40% of patients with SLE have aPL positivity (Mok et al., 2005) but less than 40% of them will eventually have thrombotic events (Ruiz-Irastorza et al., 2004; Tektonidou et al., 2009). Actually, it is still unknown if APS and SLE are two manifestations of the same disease or if underlying SLE could favour the development of APS (Miyakis et al., 2006). Accordingly, distinction between primary or secondary APS it is not so easy and have to be made carefully (Miyakis et al., 2006).