Predictors of Pregnancy Outcome in Systemic Lupus Erythematosus (SLE) and Antiphospholipid Syndrome (APS)

Thrombosis and pregnancy loss are common features of systemic lupus erythematosus (SLE), particularly in the presence of antiphospholipid (aPL) antibodies. The in vivo mechanisms by which aPL antibodies lead to vascular events and, specifically, to recurrent fetal loss are largely unknown. Studies in a mouse model of antiphospholipid antibody syndrome (APS) indicate that in vivo complement activation is necessary for fetal loss caused by aPL antibodies. This study represents an effort to translate these research observations on the potential role of complement activation in the pathogenesis of aPL antibody-mediated pregnancy loss to a clinically relevant human study. In addition, studies in humans and mice have shown 1) that the balance of circulating angiogenic and antiangiogenic factors predicts preeclampsia and fetal growth restriction in healthy women, 2) circulating antiangiogenic factors cause endothelial dysfunction and abnormal placental development in animal models, and 3) complement activation leads to elevated levels of circulating antiangiogenic factors and complement inhibition prevents increased levels of antiangiogenic factors, placental dysfunction and fetal growth restriction in a mouse model of APS. This study will permit testing the hypothesis that, like in healthy women, the balance of circulating angiogenic and antiangiogenic factors predict complications in women with SLE and APS and to translate the findings in animal models into humans. The PROMISSE Study is a prospective observational study that will follow 700 pregnant patients who will be grouped and analyzed according to the presence or absence of aPL antibodies and preexisting SLE. The patients are followed regularly during the course of the pregnancy, collecting medical and obstetrical information as well as serial blood specimens for complement and cytokine assays. The data obtained will be analyzed and used to identify mechanisms and predictors of poor fetal outcome. We expect that the insights provided through this study will suggest means to prevent, arrest or modify these conditions.