Maki Takemura

17β-Estradiol Up-Regulates Prostacyclin Production in Cultured Human Uterine Myometrial Cells Via Augmentation of Both Cyclooxygenase-1 and Prostacyclin Synthase Expression

Objective: To investigate whether 17β-estradiol elevates prostacyclin (PGI2) production in human myometrial cells in the middle of gestation. Methods: The concentration of 6-keto-PGF1α, a stable metabolite of PGI2, in the culture medium was assessed using enzyme-linked immunosorbent assay (ELISA). Western blot analysis and quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) using TaqMan (Applied Biosystems, Foster City, CA) technology were performed to evaluate the expression of cytosolic phospholipase A2 (cPLA2), cyclooxygenase-1 (COX-1), COX-2, and prostacyclin synthase (PGIS) in cultured human myometrial cells prepared from second trimester pregnant women (n = 3) after stimulation with 17β-estradiol. Results: Treatment with 17β-estradiol (4-400 nM) dose-dependently elevated PGI2 secretion from cultured human myometrial cells. Western blot analysis detected cPLA2 and COX-1 and PGIS protein expression in the cultured human myometrial cells; however, COX-2 protein expression was below the detection sensitivity. Stimulation with 40-nM 17β-estradiol significantly up-regulated protein and mRNA expression of both COX-1 and PGIS. Conclusion: 17βEstradiol from placenta may contribute to the augmentation of PGI2 production in the human myometrium in the middle of gestation via up-regulation of both COX-1 and PGIS expression.

Cyclic mechanical stretching and interleukin-1α synergistically up-regulate prostacyclin secretion in cultured human uterine myometrial cells

Prostacyclin (PGI2), a potent uterine smooth muscle relaxant, is postulated to be a major prostaglandin (PG) secreted from the human myometrium. PGI2metabolite concentrations in the maternal plasma were reported to be elevated during pregnancy, especially during labor. Recently, we developed cultured human myometrial cells from pregnant women and reported that cyclic mechanical stretching mimicking labor increased PGI2secretion from these cells by up-regulating PGI2synthase promoter activities. Since elevation of cervical/vaginal interleukin-1α (IL-1α) concentrations is also a characteristic feature of delivery, and IL-1α is a known stimulator of PGsynthesis, we investigated a possible synergistic effect of cyclic mechanical stretching and IL-1α on PGI2production in cultured human myometrial cells. Treatment with IL-1α (10 ng/ml) significantly augmented (4- to 60-fold) the secretion of PGI2, prostaglandin E2(PGE2), prostaglandin F2α(PGF2α) and thromboxane A2(TXA2) from cultured human myometrial cells obtained from non-pregnant and pregnant women as well as in cultured human umbilical artery and cultured human coronary artery smooth muscle cells (p<0.05 for all comparisons). However, labor-like cyclic mechanical stretching up-regulated IL-1α-augmented PGI2secretion from myometrial cells obtained from nonpregnant and pregnant women 2.1- to 2.8-fold (p<0.05 for all comparisons), but not PGE2, PG F2αnor TXA2. Moreover, such an augumentation of PGI2secretion by cyclic mechanical stretching was not observed in cultured human umbilical artery nor in cultured human coronary artery smooth muscle cells. These results suggest that cyclic mechanical stretching by labor, in concert with IL-1α stimulation, contributes to the increase in myometrial PGI2secretion during delivery.