Matrix metalloproteinase-9 and tissue inhibitor of matrix metalloproteinase-1: a possible role in the pathogenesis of endometriosis

BACKGROUND: Matrix metalloproteinases (MMPs) are a family of endopeptidases which play a role in the degradation and turnover of extracellular matrix proteins. Their action is regulated by specific tissue inhibitors called tissue inhibitors of metalloproteinases (TIMPs). METHODS: We measured the concentrations of total and active MMP-9 in peritoneal fluid of infertile women with mild or moderate endometriosis (n = 22) and compared them with those in a control group of infertile patients (n = 21). RESULTS: We found that the mean (+/-SD) total concentrations of MMP-9 in the peritoneal fluid of patients with endometriosis was 6.2 +/- 1.8 ng/ml, in comparison with 2.9 +/- 2.6 ng/ml in the control group (P = 0.001). Concentrations of active MMP-9 did not differ significantly between the groups. The concentrations of TIMP-1, after logarithmic transformation, were significantly lower (P = 0.017) in endometriotic peritoneal fluids than in peritoneal fluid of control women, 1.02 +/- 0.21 ng/ml and 1.16 +/- 0.18 ng/ml respectively. No correlation between stage of disease, steroid hormone concentration, MMP-9 (total and active) and TIMP-1 was found. CONCLUSIONS: These results suggest that a disturbed equilibrium exists between MMP-9 and TIMP-1 in peritoneal fluid of women with endometriosis. This may play an important role in the pathogenesis of the disease.