Induction of surfactant protein A expression by cortisol facilitates prostaglandin synthesis in human chorionic trophoblasts

Abstract

Context: Surfactant protein A (SP-A) may be an important link between the maturation of fetal organs and the initiation of parturition. However, the local expression of SP-A and the effect of SP-A on prostaglandin synthesis in human fetal membranes have not been resolved.

Objective: Our objective was to examine SP-A expression and the effect of SP-A on prostaglandin synthesis in human fetal membranes.

Design: SP-A expression was examined with immunohistochemistry and PCR. The effect of SP-A on prostaglandin synthesis was investigated in cultured human chorionic trophoblasts.

Patients: Patients were normal-term pregnant women undergoing elective cesarean sections.

Results: Both SP-A protein and mRNA were present in amnion epithelial cells, fibroblasts, and chorionic trophoblasts. Cortisol (10(-7) and 10(-6) M, 24 h) induced SP-A expression in cultured chorionic trophoblasts, which could be blocked by the glucocorticoid receptor antagonist RU486. Treatment of chorionic trophoblasts with SP-A (10-100 microg/ml, 24 h) caused a dose-dependent increase of prostaglandin E2 release and an induction of cyclooxygenase type 2 but not cytosolic phospholipase A2 and microsomal prostaglandin E synthase expression.

Conclusions: SP-A can be synthesized locally in human fetal membranes, which can be induced by glucocorticoids. SP-A appeared to induce prostaglandin E2 synthesis in chorionic trophoblasts via induction of cyclooxygenase type 2 expression.