Differential regulation in human amnion epithelial and fibroblast cells of prostaglandin E2 production and prostaglandin H synthase-2 mRNA expression by dexamethasone but not tumour necrosis factor-α

Previous studies have identified both pro-inflammatory cytokines and glucocorticoids as positive regulators of amnion prostaglandin (PG) biosynthesis. The stimulatory effects of dexamethasone (Dex), a glucocorticoid agonist, on prostaglandin endoperoxide H synthase (PGHS)-2 mRNA expression and PG biosynthesis in amnion have been attributed to an atypical response by the mesenchymal cells of the amnion. The objective of this study was to confirm previous findings concerning cell type-dependant Dex-induced upregulation of PGHS-2 mRNA expression and PG production using separated amnion cell populations, in comparison with the effects of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha). Amnion cells from placentae delivered at term by caesarian section were isolated by tryptic digestion and epithelial cells were then separated from mesenchymal cells by differential absorption onto plastic. After 24-72 h, the two cell populations were passaged and sub-cultured. Cells were treated with Dex (10(-9)-10(-6) M) or TNF-alpha (0.1-50 ng/ml) or media alone. Thereafter, PGE(2) production was determined and PGHS-2 mRNA content analysed by a competitive quantitative RT-PCR method established and validated for this study. PGE(2) production in fibroblast-enriched cultures was increased to 310 +/- 41 per cent (mean +/- SEM, n=4 wells per treatment point) of control in the presence of 10(-8) M Dex. Conversely, PGE(2) production in Dex-treated amnion epithelial cells was decreased to 67 +/- 24 per cent of control. Altered PGE(2) biosynthesis was accompanied by the upregulation of PGHS-2 mRNA in amnion fibroblasts but not in epithelial cells. TNF-alpha increased PG output and PGHS-2 expression independent of cell type. Glucocorticoids therefore appear to have opposing effects on PG biosynthesis in the two major cellular components of the human amnion. (C) 2000 Harcourt Publishers Ltd.