Background: Decidua is in close contact with the fetal trophoblasts, and involved in immune relationship of mother to fetus. However, the roles of decidua and decidual stromal cells (DSC) in materno-fetal immune regulation remain to be elucidated. In the present study, the expression and regulation of chemokines and their receptors in decidua and DSCs were investigated.
Methods and results: The transcription of 18 chemokine receptors in human first-trimester decidual tissue and DSC were first analysed by RT-PCR. Among these receptors, C-C motif chemokine receptor-2 (CCR2) was highly transcribed. It was demonstrated by RT-PCR and immunostaining that both CCR2 and its major ligand, C-C motif chemokine ligand 2 (CCL2, monocyte chemoattractant protein-1), were expressed in decidua and DSC. We then detected CCL2 in the supernatant of primary cultures of DSC by enzyme-linked immunosorbent assay. It was shown that DSC secreted CCL2 spontaneously and continuously over 72 h (21.72 +/- 2.34 ng/ml), and the CCR2 antagonist RS102895 and an inhibitor of the map kinase kinase/mitogen-activated protein kinase (ERK/MAPK) signal pathway decreased significantly the CCL2 secretion of DSC (both P < 0.05). We further studied effects of the pregnancy-associated hormones, estrogen, progesterone or HCG on CCL2 secretion by DSC. CCL2 secretion by DSC was up-regulated by estrogen, progesterone or HCG.
Conclusions: CCR2 and CCL2 are co-expressed by human first-trimester DSC and decidual tissue. CCL2 is secreted in an autocrine manner through the ERK/MAPK pathway, and is up-regulated by the pregnancy-associated hormones, estrogen, progesterone and HCG, which suggests that CCL2 may play an important role at materno-fetal interface.