Expression of β Chemokines in Explants and Trophoblasts from Early and Term Human Placentae

PROBLEM Implantation of human embryo requires expression of inflammatory cytokines and local attraction of T cells and natural killer (NK) cells. Chemokines are chemoattractants for these cells in classical inflammation. We speculated that they could also be involved in implantation. METHOD OF STUDY We assessed by enzyme-linked immunosorbent assay (ELISA), reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry the presence of three classical beta chemokines Macrophage Inflammatory Protein 1 (MIP1)alpha, MIP1beta and Regulated upon activation, normal T cells expressed and secreted (RANTES) in cultures of placental villi or isolated trophoblasts derived from human first trimester and term placenta. RESULTS Explant culture assays were positive for these three chemokines, with important quantitative variations between individuals. Half of the highly purified trophoblasts cultures were found by ELISA and RT-PCR to secrete in vitro MIP1alpha and MIP1beta. RANTES was never detected by ELISA in trophoblasts cultures, albeit we could detect a low amount of messenger RNA. Immunohistochemistry experiments show that Hofbauer cells and the trophoblast layer are a secretion site of MIP1beta in term placenta, and that cytotrophoblasts are able to secrete this chemokine in early placenta. CONCLUSION Human placenta is a site of secretion of chemokines that could be involved in establishment of pregnancy.