Expression of αvβ3 and α4β1 integrins throughout the putative window of implantation in a cohort of healthy fertile women

Abstract

Background. Blastocyst implantation is a dynamic process requiring a specific cascade of cellular interactions and endometrial changes. The aim of this prospective observational study was to investigate the endometrial expression of αVβ3 and α4β1 integrins throughout the window of implantation in healthy fertile women.Materials and methods. Forty fertile women (mean age 29.7 ± 6.2 years) were recruited for this study. All underwent two endometrial biopsies in a single menstrual cycle. The first biopsy was performed on postovulatory day 6, while the second was taken on postovulatory day 8. Histological dating and immunohistochemical assessments of αVβ3 and α4β1 integrins were analyzed. Oestradiol and progesterone serum concentrations were also measured at the time of biopsy.Results. Second endometrial biopsy could not be performed in two of the 40 women (5%) because their menses had started in advance. No inflammatory or reactive phenomena were observed after biopsy. All the samples showed an in‐phase endometrium. αVβ3 integrin expression was found in 21 out of the 38 first biopsies and in all 38 second biopsies (55.2% vs. 100%, p < 0.001). α4β1 integrin expression was not significantly different between first and second biopsies (68.4% and 76.3%, NS). Oestradiol and progesterone serum concentrations were similar throughout the implantation window. Twelve of the 38 women (31.6%) conceived within 12 months of completing the study. All these had significantly higher αVβ3 integrin expressions in mid‐luteal phase biopsies compared with those who did not conceive.Conclusions. These immunohistochemical findings demonstrate that both αVβ3 and α4β1 integrins have a spatial and temporal expression throughout the implantation window in the endometrium of fertile women. Moreover, the shortage of αVβ3 integrin expression during the mid‐luteal phase results in a detrimental effect for blastocyst implantation.