Increased phospholipase A2 and thromboxane but not prostacyclin production by placental trophoblast cells from normal and preeclamptic pregnancies cultured under hypoxia condition

In this study we determined whether hypoxia could promote vasoactivator thromboxane (TX) and prostacyclin (PGI(2)) as well as phospholipase A(2) (PLA(2)) production by placental trophoblast cells (TCs) from normal and preeclamptic (PE) pregnancies. Placentas were obtained immediately after delivery from normal (n = 9) and preeclamptic (n = 9) pregnancies. TCs were isolated by dispase digestion of villous tissue and purified by Percoll gradient centrifugation. TCs (5 x 10(6) cells/well) were cultured with Dulbecco's Modified Eagles Medium (DMEM) under hypoxia condition (2% O-2/5% CO2/93% N-2) for 48 h. TCs Cultured under normoxia condition (5% CO2/air) were used as control. Culture medium was collected at the end of incubation. Productions for TX, PGI(2) and PLA(2) were measured by ACE (TM) competitive enzyme immunoassay (EIA). Comparisons were made using the Mann-Whitney U test or paired t-test and the data arc expressed as mean +/- SE (pg/mu g cellular protein). Significance was set at a p-value of < 0.05. We found: (1) PE-TCs produced more TXB2 and PLA(2) than normal-TCs under normoxia conditions, TXB2: 4.33 +/- 1.03 vs. 1.84 +/- 0.29 pg/mu g protein, p < 0.05; PLA(2): 0.38 +/- 0.08 vs. 0.21 +/- 0.03 pg/mu g protein, p < 0.05, respectively. (2) Hypoxia promoted both PE- and normal-TCs to generate more TXB2 and PLA(2), TXB2: 6.36 +/- 1.72 vs. 3.05 +/- 0.45 pg/mu g; PLA(2): 0-52 +/- 0.10 vs. 0.30 +/- 0.04 pg/mu g, respectively. (3) No change in 6-keto PGF1 alpha production was observed for normal-TCs or PE-TCs when compared under normoxia vs. hypoxia condition, normal-TCs: 0.20 + 0.05 vs. 0,21 +/- 0.05 pg/mu g; PE-TCs: 0.38 +/- 0.05 vs. 0.36 +/- 0.04 pg/mu g, respectively. We concluded that hypoxia promotes both PLA(2) and TX, but not PGI(2), production by placental trophoblast cells cultured under hypoxia condition. These results suggest that increased PLA(2) release may alter the arachidonic acid cascade and promote TX synthesis. Relative hypoxia could contribute to the increase in TX production and result in vasoconstriction in placental vasculature in preeclampsia. (c) 2004 Elsevier Ltd. All rights reserved.