Background: During human pregnancy, 11b-hydroxysteroid dehydrogenase type 2 (11b-HSD2) plays an important role in protecting the fetus from high maternal glucocorticoid concentrations by converting cortisol to inactive cortisone. Furthermore, 11b-HSD2 is indirectly involved in the regulation of the prostaglandin inactivating enzyme 15-hydroxyprostaglandin dehydrogenase (PGDH), because cortisol reduces the gene expression and enzyme activity of PGDH in human placental cells. Objective: To examine developmental changes in placental 11b -HSD2 and PGDH gene expression during the 2nd and 3rd trimesters of human pregnancies. Methods: In placental tissue taken from 20 healthy women with normal pregnancy and 20 placentas of 17 mothers giving birth to premature babies, 11b-HSD2 and PGDH mRNA expression was determined using quantitative real-time PCR. Results: Placental mRNA expression of 11b-HSD2 and PGDH increased signi®cantly with gestational age r 0X55Y P 0X0002 and r 0X42Y P 0X007X In addition, there was a signi®cant correlation between the two enzymes r 0X58Y P , 0X0001X Conclusions: In the course of pregnancy there is an increase in 11b-HSD2 and PGDH mRNA expression in human placental tissue. This adaptation of 11b-HSD2 prevents increasing maternal cortisol concentrations from transplacental passage and is exerted at the gene level. 11b-HSD2 upregulation may also lead to an increase in PGDH mRNA concentrations that, until term, possibly delays myometrial contractions induced by prostaglandins.

Cortisol reduces the activity of the PG-inactivating enzyme 15-hydroxyprostaglandin dehydrogenase (PGDH) in human placental cells. The objective was to investigate a possible relation between 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), converting cortisol to cortisone, and PGDH gene expression in the placenta of patients with preeclampsia. In placental tissue taken from 20 healthy women with normal pregnancy, 20 premature babies born after labor before term, and 18 neonates after preeclamptic pregnancy, 11beta-HSD2 and PGDH messenger RNA (mRNA) expression was determined using quantitative TaqMan real-time PCR and quantitative competitive PCR. When comparing matched pairs, there were 3-fold lower 11beta-HSD2/glyceraldehyde-3-phosphate dehydrogenase (11beta-HSD2/GAPDH) mRNA levels in placentas of patients with preeclampsia than in controls [0.18 +/- 0.04 relative units (RU) and 0.61 +/- 0.10 RU, P = 0.0003]. We also found a 2-fold reduction in placental PGDH/GAPDH mRNA concentrations (0.28 +/- 0.15 RU and 0.50 +/- 0.18 RU, P = 0.0003). PGDH and 11beta-HSD2 mRNA levels correlated significantly (r = 0.66, P < 0.0001). In term placenta, 11beta-HSD2/GAPDH, but not PGDH, showed a significant correlation to birth weight (r = 0.43, P = 0.01) and to placental weight (r = 0.47, P = 0.01). Results could be confirmed by competitive PCR. We conclude that, in preeclampsia, 11beta-HSD2 mRNA expression is reduced, leading to the known decrease of 11beta-HSD2 activity. By means of an autocrine or paracrine mechanism, the diminished conversion of placental cortisol may lead to reduced PGDH mRNA expression as found in the present study.