Inflammatory insults alters apoptotic expression and gelatinase activity in the fetal membranes at the supracervical site

Introduction: Preterm labour and preterm premature rupture of the fetal membranes (PROM) represent major challenges to contemporary obstetrics. Although factors like smoking and infection are associated with PROM and preterm labour, the exact cause of this early rupture remains unclear. Available data support the hypothesis that weakening prior to term combined with collagen remodeling are antecedents to spontaneous fetal membrane (FM) rupture. The mediators involved in the formation of the supracervical site (SCS), however, remain equivocal. The aim of this study, therefore, was to determine the effect of lipopolysaccharide (LPS) and hypoxanthinenxanthine oxidase (HX-XO) on apoptosis and extracellular matrix remodeling in FMsfrom both the SCS and distal sites (DS).Study design: Bonneys blue dye was applied transcervically to the FM prior to term elective Caesarean section (n=6). After delivery, the SCS were visually identifi ed by a blue marking on the chorion facing membranes. FMs were also obtained from a DS, near the peri-placental membranes. Amnion and chorion were separated and fragments were incubated in the absence or presence of 10mg/ml LPS or 0.5mM HX-15mU/ml XO for 24h. Protein expression of various apoptotic endpoints were determined by Western blot and matrix metalloproteinase (MMP)-2 and -9 activities was determined by zymography.Results: After 24h incubation with HX-XO, distal amnion FM increased protein expression of the pro-apoptotic proteins Bax and Smac compared to the basal. Furthermore, LPS treatment signifi cantly increased Smac protein expression in the distal amnion. Secretory MMP-2 and MMP-9 enzyme activity was signifi cantly lower in SCS chorion and distal amnion with HXXO treatment. Conclusion: SCS amnion is less responsive to exogenous inflammatory stimuli and oxidative stress than amnion obtained from distally to this site. This may represent a protective or adaptive mechanism to prevent damage from further oxidative insult in utero. Distal amnion responds to insult by increasing apoptosis which would lead to proteolysis/damage to the structural proteins that compromises FM integrity thus reduce MMP activity.