Expression of beta chemokines in explants and trophoblasts from early and term human placentae

PROBLEM: Implantation of human embryo requires expression of inflammatory c ytokines and local attraction of T cells and natural killer (NK) cells. Che mokines 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 immunohistoche mistry the presence of three classical beta chemokines Macrophage Inflammat ory Protein 1 (MIP1)alpha, MIP1 beta and Regulated upon activation, normal T cells expressed and secreted (RANTES) in cultures of placental villi or i solated trophoblasts derived from human first trimester and term placenta. RESULTS: Explant culture assays were positive for these three chemokines, w ith important quantitative variations between individuals. Half of the high ly purified trophoblasts cultures were found by ELISA and RT-PCR to secrete in vitro MIP1 alpha and MIP1 beta. RANTES was never detected by ELISA in t rophoblasts cultures, albeit we could detect a low amount of messenger RNA. Immunohistochemistry experiments show that Hofbauer cells and the trophobl ast layer are a secretion site of MIP1 beta in term placenta, and that cyto trophoblasts 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.