Protein profiling of human endometrial tissues in the midsecretory and proliferative phases of the menstrual cycle

Objective To identify the proteins displaying differential expression in midsecretory phase endometrium as compared with proliferative phase endometrium. Design Prospective study with two groups of women in the midsecretory or proliferative phase. Setting Clinical research outpatient department. Patient(s) Healthy, regularly cycling women of proven fertility. Intervention(s) Collection of endometrial biopsy samples. Main Outcome Measure(s) Image analysis software was used to compare two-dimensional protein maps of midsecretory phase endometrial tissues (MSE) with maps of proliferative phase endometrial tissues (PROE) and midsecretory phase uterine fluids (MSU). Matrix-assisted laser desorption/ionization time of flight in tandem (MALDI-TOF-TOF) analysis was carried out to identify eight proteins that were differentially expressed between the two phases and also to identify the spots that shared similar coordinates in the two-dimensional maps of MSE and MSU. Result(s) Densitometry analysis and subsequent MALDI-TOF-TOF analysis revealed up-regulation of calreticulin, the β chain of fibrinogen, adenylate kinase isoenzyme 5, and transferrin in the PROE and of annexin V, α1-antitrypsin, creatine kinase, and peroxidoxin 6 in MSE compared with the other phase. Superimposition of the two-dimensional maps of MSE on those of MSU revealed the presence of heat-shock protein 27, transferrin, and α1-antitrypsin precursor in both endometrial tissues and uterine secretions. Conclusion(s) Differentially expressed proteins identified in the present study could be of relevance in endowing the endometrium with receptivity.