[Study on the relationship between altered expression of annexin A4 and endometrial receptivity during the implantation window in infertile patients with endometriosis].

OBJECTIVE: To identify the differential expressed proteins, and to investigate the relationship between altered expression of annexin A4 during window of implantation [WOI (at day-6 after ovulatory day)] in infertile patients with endometriosis and endometrial receptivity. METHODS: Two-dimensional fluorescence differential in-gel electrophoresis (2D-DIGE) and matrix-assist laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) were used to detect protein expression in endometrial WOI in 10 infertile cases with endometriosis as endometriosis group and 10 infertile cases with tubal factors as control group. The semi-quantitative validation of annexin A4 in the eutopic endometrial tissue during WOI was analyzed by western blot. RESULTS: By comparing protein profiles, there were 7 meaningful differential proteins during WOI in infertile patients with endometriosis. One protein with an isoelectric point of 5.84 and relative molecular weight of 36 100 were down regulated 348% in samples of endometriosis group. It was identified as annexin A4 by mass spectrometry. By western blot, relative intensity of annexin A4 in endometriosis group was 7.2 ± 0.9, which was lower than 17.8 ± 2.6 in control group significantly (t = 7.654, P = 0.002). CONCLUSION: Lower expression of annexin A4 during WOI in infertile patients with endometriosis might be associated with the decrease of endometrial receptivity.