Impact of Progesterone on Molecular Mechanisms of Preterm Premature Rupture of Membranes.

The role and mechanisms of progesterone in preterm premature rupture of membranes (PPROM) remains unclear. This study aims to investigate the molecular mechanisms of action of progesterone in pre-labor full-term fetal amniotic membrane cells with and without stimulation by microbial, pro-inflammatory, or thrombogenic agents. Fetal amniotic membranes were collected from 30 women with a normal singleton pregnancy undergoing elective cesarean section at term prior to the onset of labor. The human amniotic epithelial cells isolated were pretreated with and without medroxyprogesterone acetate for 24 h. Then, cells were treated with and without TLR/NLR agonists, pro-inflammatory cytokines, or thrombin for 48 h. Semi-quantitative RT-PCR, Western blot, and caspase-3 activity measurement were performed. Progesterone stimulation decreased the expression of TLR2, TLR5, and Nod2 genes (alone and/or in combination with TLR/NLR agonists) and decreased the expression of IL-1β and IL-8 genes increased by stimulation with specific agonists for TLR2, TLR4, TLR5, Nod1, and Nod2. Moreover, progesterone decreased thrombin-induced IL-8 gene expression. Progesterone also decreased expression of Bax and Bid proteins (pro-apoptotic factors) increased by stimulation with pro-inflammatory cytokines (TNF-α, NGAL, IL-18, and IL-1β) and thrombin. Progesterone stimulation alone as well as co-stimulation with TNF-α, NGAL, IL-18, IL-1β, or thrombin with progesterone either increased, decreased, or did not change the expression of Bcl-2, Bcl-XL, or XIAP genes (anti-apoptotic factors). These data suggest progesterone plays protective roles against PPROM through anti-microbial, anti-inflammatory, and anti-thrombogenic actions on human-term fetal amniotic membrane cells. Progesterone alters pro-inflammatory cytokine- and thrombin-induced apoptosis by controlling the expression of pro-apoptotic and anti-apoptotic factors.