Trophoblast and placental villous core production of lipid peroxides, thromboxane, and prostacyclin in preeclampsia

Abstract

Placentas obtained from women with preeclampsia produce more lipid peroxides and more thromboxane, but less prostacyclin, than normal. The tissue compartments within the placenta that are responsible for this are not known. The placenta is a heterogeneous tissue compartmentalized into trophoblast cells and villous core tissue that is comprised of stromal and vascular tissue. In this study we determined the placental compartments responsible for increased production of lipid peroxides and thromboxane in preeclampsia. Placentas were obtained from six normally pregnant women and seven women with preeclampsia. Trophoblast cells and villous core tissues were isolated and incubated in Dulbecco's Modified Eagle's Medium for 48 h. Samples were collected at 0, 2, 6, 16, 28, and 48 h of incubation and analyzed spectrophotometrically for lipid peroxides by a peroxide equivalent assay and for thromboxane and prostacyclin by RIA of their stable metabolites, thromboxane-B2 and 6-keto-prostaglandin-F1 alpha. Trophoblast cells isolated from preeclamptic placentas produced significantly more lipid peroxides (1972 +/- 502 vs. 1102 +/- 335 pmol/micrograms protein after 48 h of incubation), more thromboxane (328 +/- 57 vs. 153 +/- 53 pg/microgram at 48 h), and more prostacyclin (50 +/- 11 vs. 13 +/- 3 pg/microgram at 48 h, respectively) than trophoblast cells isolated from normal placentas. Villous core tissue isolated from preeclamptic placentas produced significantly more lipid peroxides (455 +/- 107 vs. 241 +/- 34 pmol/microgram) and more thromboxane (148 +/- 51 vs. 76 +/- 14 pg/microgram) than normal villous core tissue, but there was no difference in prostacyclin production (36 +/- 11 vs. 40 +/- 9 pg/microgram). Because of the increase in thromboxane production, the ratio of thromboxane to prostacyclin was higher in preeclamptic than normal villous core tissue (6.29 vs. 2.17). Comparison of production by different compartments within the placenta demonstrated that lipid peroxides and thromboxane were primarily produced by the trophoblast cells and stromal tissue, whereas prostacyclin was primarily produced by the vascular tissue. We conclude that increased placental production of lipid peroxides and thromboxane in preeclampsia originates from both the trophoblast cell and the villous core compartments. As the placenta secretes lipid peroxides, the trophoblast cells could be a source of increased lipid peroxides in the maternal circulation of women with preeclampsia. The increased ratio of thromboxane to prostacyclin in the villous core could be responsible for increased placental vasoconstriction.