IL-1β Treatment Does not Co-ordinately Up-regulate mPGES-1 and COX-2 mRNA Expression, but Results in Higher Degree of Cellular and Intracellular Co-localization of their Immunoreactive Proteins in Human Placenta Trophoblast Cells

PGE2 is involved in initiation and progression of labor in many species. Biosynthesis of PGE2 is mediated by cyclooxygenases (COX) and prostaglandin E synthases (PGES). mPGES-1 and COX-2 form an inducible pathway for PGE2 production in many cell systems.In this study we investigated whether mPGES-1 is involved in cytokine induced PGE2 biosynthesis in human trophoblast cells.We have evaluated the cellular and intracellular co-localization of mPGES-1 and COX-2, as well as cPGES and COX-1 in human trophoblast cells by dual immunofluorescent staining. The effect of IL-1β on mPGES-1 and COX-2 co-localization, such as would occur with infection, and the regulatory effects of pro-inflammatory cytokines IL-1β and TNF-α on transcriptional activity of mPGES-1 and COX-2 in these cells were also studied. We found that in cultured unstimulated trophoblasts, some cells expressed predominantly either mPGES-1 or COX-2, though there were cells co-expressing both enzymes. With IL-1β treatment, mPGES-1 and COX-2 became more consistently co-localized. mPGES-1 was not transcriptionally co-induced with COX-2 by the cytokine treatment. We conclude that mPGES-1 is not involved in the inducible COX-2 mediated pathway for PGE2 biosynthesis at the transcriptional level, however, the treatment with IL-1β results in a higher degree of co-ordination of the mPGES-1 and COX-2 protein immunolocalization, eliciting PGE2 synthesis.