Expression of extracellular matrix metalloproteinase inducer in human placenta and fetal membranes at term labor

Matrix metalloproteinases (MMPs) are the main mediators of extracellular matrix (ECM) degradation during human parturition. However, the mechanisms involved in regulation of MMP production during parturition remain poorly understood. Recently, an extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to play a key role, as a local regulator, in stimulating MMP production in cancer systems. Whether EMMPRIN is expressed and stimulates MMP production in human placenta and fetal membranes is presently unknown. In this study, we investigated the expression of EMMPRIN at the levels of mRNA and protein in human term placenta and fetal membranes with or without labor. Western blot analysis showed that EMMPRIN protein was detected in term placenta and fetal membranes at two molecular masses of 40 and 65 kDa (glycosylated protein) and one of approximately 30 kDa (nonglycosylated protein). The ratio of 65 kDa EMMPRIN to total EMMPRIN significantly increased (P < 0.05) in term labor chorio-decidua and amnion compared with nonlabor chorio-decidua and amnion. Immunohistochemical analysis revealed that EMMPRIN was expressed in placental syncytiotrophoblast, amniotic epithelial cells, trophoblast cells of chorion laeve, and decidua parietalis. EMMPRIN was also detected at the mRNA level using RT-PCR in cultured placental syncytiotrophoblast, amniotic epithelial cells, and chorionic trophoblast cells. We conclude that human placenta and fetal membranes express EMMPRIN, with the potential to stimulate MMP production, thereby facilitating fetal membrane rupture and leading to detachment of the placenta and fetal membranes from the maternal uterus at the time of parturition.