Effect of endometriosis on the protein expression pattern of follicular fluid from patients submitted to controlled ovarian hyperstimulation for in vitro fertilization.

BACKGROUND The aim of this study was to evaluate protein expression profile and quantify the proteins present in follicular fluid (FF) samples from women with endometriosis and pregnant women without endometriosis. METHODS A prospective case-control study was carried out including women with Stage III or IV endometriosis (Group I) and pregnant women without endometriosis (Group II), both at the maximum age of 35 years. Women were submitted to controlled ovarian stimulation for in vitro fertilization, and FF was collected after ultrasound-guided ovarian aspiration. FF from both ovaries was pooled, and patient samples were pooled according to Group I or II. Pooled protein samples were separated and analyzed by MudPIT (multidimensional protein identification technology followed by Expression(E) and label-free quantification with ProteinLynxGlobalServer 2.4v, Identity(E) and Expression(E) software). RESULTS A total of 416 proteins or randomic sequence were identified, 62 proteins differentially expressed between Groups I and II. One (1.6%) was expressed at a higher level and 36 (58.1%) were uniquely expressed in Group I, whereas 8 (12.9%) were expressed at a higher level and 17 (27.4%) were uniquely expressed in Group II. Of all these, 15 (24.2%) are related to binding, 1 (1.6%) to immune response, 8 (12.9%) to cell division, 3 (4.8%) to cellular metabolism, 16 (25.8%) to general function and 19 (30.6%) do not yet present an identified function. CONCLUSIONS Protein expression profiles of patients with and without endometriosis identified at least 64 proteins differentially expressed, which may be related to the physiopathology of endometriosis. These proteins may additionally be useful in determining potential biomarkers for diagnostics, as well as for therapeutic intervention in women with infertility due to endometriosis.