Increased circulating MMP-2 levels in infertile patients with moderate and severe pelvic endometriosis

The current study compares the levels of matrix metalloproteinase (MMP)-2 and MMP-9 in the follicular fluid (FF) of infertile patients with and without endometriosis submitted to ovarian stimulation for in vitro fertilization and the levels of MMP-2 in the serum of the same patients. We also evaluated whether the severity of endometriosis can influence serum and/or FF concentration of these metalloproteinases. A cross-sectional study was conducted on 30 patients: stage I/II endometriosis (n = 10), stage III/IV endometriosis (n = 10), and control (infertility due to tubal and/or male factor; n = 10). Blood samples for the analysis of MMP-2 levels were obtained during the early follicular phase of the menstrual cycle. The FF samples for the analysis of MMP-2 and MMP-9 were obtained on the day of oocyte retrieval. The concentrations of MMP-2 and MMP-9 were determined by zymography. No intragroup or intergroup difference was observed in MMP-2 or MMP-9 levels in FF. Significantly higher MMP-2 levels were detected in the serum of infertile women with stage III/IV endometriosis compared to women with stage I/II endometriosis. In conclusion, no differences were observed in the follicular levels of MMP-2 and MMP-9 between infertile patients with and without endometriosis. However, the levels of MMP-2 were significantly higher in the serum of infertile women with advanced stages of endometriosis. Taken together, the present results demonstrate that advanced pelvic endometriosis severity is related to higher serum MMP-2 levels but does not influence follicular MMP-2 or MMP-9 levels in periovulatory follicles obtained from stimulated cycles.