Antiphospholipid antibodies inhibit prostaglandin release by decidual cells of early pregnancy: possible involvement of extracellular secretory phospholipase A2.

To investigate the effect of antiphospholipid antibodies on eicosanoid production by human decidual cells and the in vitro interaction between antiphospholipid antibodies and secretory phospholipase A2.Cultures of human decidual cells from early pregnancy.All decidual specimens were obtained from the Obstetrics and Gynecology Department of the Catholic University, Rome, Italy.Patients were undergoing operative laparoscopy for extrauterine pregnancy, with a period of amenorrhea ranging from 6 to 9 weeks.Decidual samples were collected at laparoscopy by routine uterine curettage.Decidual cells were incubated with antiphospholipid antibodies, and eicosanoids (prostaglandin [PG] E2, PGF2alpha, and thromboxane B2) were assayed by RIA after 24 hours of culture. In vitro interactions between antiphospholipid antibodies and secretory phospholipase A2 were investigated with use of a modified ELISA for phospholipase A2.Antiphospholipid antibodies reduced eicosanoid release from decidual cells in a dose-dependent fashion. In vitro assays showed that antiphospholipid antibodies bound secretory phospholipase A2 and that a competition occurred between antiphospholipid antibodies and secretory phospholipase A2 for the common substrate cardiolipin.In light of the critical role played by eicosanoids in decidual function, we suggest that an interaction between antiphospholipid antibodies and secretory phospholipase A2 occurring in vivo might impair important cellular communications at the decidual level in the antiphospholipid antibody syndrome.The presence of antiphospholipid antibodies is often associated with poor obstetric histories, including recurrent abortion, intrauterine growth retardation, and preeclampsia. While it has been suggested that these antibodies can affect the function of vascular endothelial cells at the decidual and placental levels, their cellular target and mode of action remain to be determined. Findings are presented from a study to investigate the effect of antiphospholipid antibodies upon eicosanoid production by human decidual cells and the in vitro interaction between antiphospholipid antibodies and secretory phospholipase A2. Specimens of decidualized endometrium were obtained by routine curettage from patients undergoing operative laparoscopy for extrauterine pregnancy in the Obstetrics and Gynecology Department of the Catholic University in Rome, Italy. Analysis determined that antiphospholipid antibodies reduce eicosanoid release from decidual cells in a dose-dependent manner, while in vitro assays showed that antiphospholipid antibodies bound secretory phospholipase A2 and that competition occurred between antiphospholipid antibodies and secretory phospholipase A2 for the common substrate cardiolipin. An interaction between antiphospholipid antibodies and secretory phospholipase A2 occurring in vivo may impair important cellular communications at the decidual level in the antiphospholipid antibody syndrome.