In the present study, we examined the embryonic regulation ofβ 3 integrin in human endometrial epithelial cells (EEC) at the protein level and analyzed putative embryonic factors responsible for this regulation. The model employed is based on a clinical in vitro fertilization program in which single human embryos were cocultured with EEC until blastocyst stage and then transferred back to the uterus. After embryo transfer, EEC wells were divided according to the embryonic status reached: EEC with embryos that achieved the blastocyst stage, EEC with arrested embryos, and EEC without embryos. Immunostaining for β3 was positive in plasma membrane of EEC. Flow cytometry showed a mean percentage ofβ 3-stained cells of 24.1 ± 5.7 in EEC cocultured with embryos that achieved the blastocyst stage (n = 13) vs. 9.5 ± 1.6 (P < 0.05) in those EEC cultured with arrested embryos (n = 12). Immunostaining for α1 and α4 integrins was negative in EEC monolayers studied, regardless of the presence or absence of embryos, and these findings were confirmed by flow cytometry. The possibility that the embryonic IL-1 system and leukemia inhibitory factor were involved in the endometrial β3 up-regulation was investigated by neutralizing experiments demonstrating a significant inhibition of β3-stained cells when EEC monolayers were cultured in the presence of EEC/blastocyst-conditioned media with (n = 4) vs. without (n = 8) antihuman interleukin (IL)-1α + IL-1β (1.65% vs. 14.6%; P < 0.05). Dose-response experiments further demonstrated an up-regulation of β3 positive cells when IL-1α + IL-1β were added to the medium at a concentration of 10 pg/mL compared with control medium without added cytokines (40% vs. 20%, n = 4). The functional relevance of the EEC β3 up-regulation was tested using a mouse blastocyst adhesion assay. More mouse blastocysts attached to EEC previously in contact with human blastocyst (72.7%) compared with those EEC previously in contact with arrested embryos (40%). Our results demonstrate the selective effect of a developing human embryo on EEC expression of β3, which is maximal when a human blastocyst instead of an arrested embryo is considered. Furthermore, the embryonic IL-1 system seems to be involved in the EECβ 3 up-regulation, reinforcing the concept of precise paracrine cross-talk between blastocyst and endometrial epithelium during embryonic implantation.
Hormonal and embryonic regulation of chemokine receptors CXCR1, CXCR4, CCR5 and CCR2B in the human endometrium and the human blastocyst
