Proteomic analysis of uterine flushings from infertile women in the proliferative phase of the menstrual cycle with respect to estrogen level

Objectives: To identify those proteins differentially expressed in the uterine cavity according to cycle day or estrogen level and to produce a two-dimensional protein map of proliferative phase uterine flushings. Materials and Methods: Uterine flushings were obtained from 31 women undergoing evaluation for infertility prior to assisted reproductive technology treatment (ART). Five patients exhibiting the lowest estrogen (E2) levels were compared with the five patients having the highest values. The uterine flushings were subjected to 2D electrophoresis before the gels were silver stained, digitally captured and subjected to semi-quantitative computerized analysis. Results: Nineteen protein spots were differentially expressed between the two groups. Seven protein spots appeared significantly more frequently in the low E2 group (p<0.05). Three proteins exhibited significantly higher mean expression in the low E2 group (p<0.05) and nine spots showed significantly higher mean expression in the high E2 group (p<0.05). Several spots that were upregulated in the high E2 group were identified as, Serotransferrin, Hemopexin precursor, Fibrinogen β-chain, α-1-antichymotrypsin and complement C4. Conclusions: The identified proteins upregulated in the high E2 group are involved in iron transport, coagulation, tissue remodelling and complement activation. The relevance of these findings in relation to uterine processes in infertility