title: Oxygen regulation of placental 11 beta-hydroxysteroid dehydrogenase 2: physiological and pathological implications.
abstract: Preeclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality. The genesis of PE is related to deficient trophoblast invasion of maternal spiral arteries, which might result in a reduction of placental (PL) oxygen (O(2)). An absence of increased O(2) that normally occurs around the 10-12th wk of gestation results in aberrant expression of genes that might contribute to the pathophysiology of PE. We examined the expression and regulation of PL 11 beta-hydroxysteroid dehydrogenase 2 (11 beta-HSD) in normal pregnancies and in PE. Two types of 11 beta-HSD exist in the placenta, 11 beta-HSD1 and 11 beta-HSD2. 11 beta-HSD2 is thought to protect the fetus from cortisol excess. In PE, both the expression and activity of PL 11 beta-HSD2 were reduced significantly compared with those in age-matched controls. As PE is associated with a reduction of PL O(2), we next investigated whether in normal pregnancy 11 beta-HSD2 expression changes at the time of the increase in O(2). 11 beta-HSD2 was detected as early as 5 wk, with expression limited to the syncytiotrophoblast (ST). At 10-12 wk, this expression increased and was also found in the cytotrophoblast and extravillous trophoblast. These results were substantiated by Western blot. The ability of O(2) to regulate 11 beta-HSD2 was determined both in cultures of villous explant from early gestation and in term trophoblast cells after incubation under 3% or 20% O(2). Villous explants cultured under 20% O(2) showed higher enzyme activity and expression compared with 3% O(2). Term trophoblast cells also exhibited higher enzyme activity at 20% vs. 3% O(2). No change in 11 beta-HSD1 expression was observed in early pregnancy or in PE. This is the first report to suggest that 11 beta-HSD2 is O(2) dependent in first and third trimester placenta during human gestation.
mesh_terms: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D015153:Blotting, Western; D002478:Cells, Cultured; D005260:Female; D005865:Gestational Age; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases / Q000032:analysis* / Q000378:metabolism; D007150:Immunohistochemistry; D010100:Oxygen / Q000008:administration & dosage / Q000494:pharmacology*; D010920:Placenta / Q000201:enzymology*; D011225:Pre-Eclampsia / Q000201:enzymology; D011247:Pregnancy; D014018:Tissue Distribution; D014327:Trophoblasts / Q000201:enzymology
chemical_list: D006913:Hydroxysteroid Dehydrogenases; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; C468387:HSD11B2 protein, human; D010100:Oxygen