Progesterone Acts via the Nuclear Glucocorticoid Receptor to Suppress IL-1β-Induced COX-2 Expression in Human Term Myometrial Cells

Abstract

Progesterone is widely used to prolong gestation in women at risk of preterm labour (PTL), and acts at least in part via the inhibition of inflammatory cytokine-induced prostaglandin synthesis. This study investigates the mechanisms responsible for this inhibition in human myometrial cells. We used reporter constructs to demonstrate that interleukin 1beta (IL-1β) inhibits progesterone driven PRE activation via p65 activation and that IL-1β reduced progesterone driven gene expression (FKBP5). Conversely, we found that the activity of a p65-driven NFκB reporter construct was reduced by overexpression of progesterone receptor B (PRB) alone and that this was enhanced by the addition of MPA and that both MPA and progesterone suppressed IL-1β-driven cyclo-oxygenase-2 (COX-2) expression. We found that over-expressed Halo-tagged PRB, but not PRA, bound to p65 and that in IL-1β-treated cells, with no overexpression of either PR or p65, activated p65 bound to PR. However, we found that the ability of MPA to repress IL-1β-driven COX-2 expression was not enhanced by overexpression of either PRB or PRA and that although the combined PR and GR antagonist Ru486 blocked the effects of progesterone and MPA, the specific PR antagonist, Org31710, did not, suggesting that progesterone and MPA act via GR and not PR. Knockdown using siRNA confirmed that both MPA and progesterone acted via GR and not PR or AR to repress IL-1β-driven COX-2 expression. We conclude that progesterone acts via GR to repress IL-1β-driven COX-2 activation and that although the interaction between p65 and PRB may be involved in the repression of progesterone driven gene expression it does not seem to be responsible for progesterone repression of IL-1β-induced COX-2 expression.

Myometrial cytokines and their role in the onset of labour

“…Our data suggest that P4 represses IL-1β-driven COX-2 expression via the glucocorticoid receptor and not PR, despite the presence of sufficient PR to modulate the expression of the P4-responsive genes (Lei et al 2012). Further, we show that P4 reduced IL-1β-driven COX-2 expression via the inhibition of AP-1 action rather than NFκB (Lei et al 2015).…”

Single-cell transcriptomics of the human placenta: inferring the cell communication network of the maternal-fetal interface

“…However, the fact that RU486 also antagonizes GR, the absence of PGR, and high expression of GR in uterine dendritic cells suggest that the observed effect on dendritic cells is mediated by P4 binding to GR. In accordance, P4 signaling via GR has been recently shown to modulate IL1B-induced COX2 expression in myometrium (Lei et al 2012). …”

Glucocorticoids and Reproduction: Traffic Control on the Road to Reproduction

“…The abortifacient drug RU486 acts as both an anti-progestin and antiglucocorticoid, which prevents discriminating between the GR- and PR-mediated effects in the uterus [114]. Cells in culture have provided a genetically tractable model to dissect the relative contribution of GR and PR, and propose cross-talk between progesterone and GR in cells of the reproductive tract [115–118]. New techniques utilizing cell-specific knockdown or targeted genome editing in vivo will help clarify the specific roles of glucocorticoids in normal reproductive physiology and stress-induced infertility.…”