Matrix metalloproteinases (MMPs) play an important role in menstruation and endometriosis; however, the membrane-type matrix metalloproteinases (MT-MMPs) are not well studied in endometriosis and adenomyosis. We analyzed MT2-MMP (MMP15) and MT3-MMP (MMP16) in eutopic endometrium with and without endometriosis and with and without adenomyosis and ectopic endometrium of deep infiltrating endometriosis (DIE), peritoneal endometriosis (PE), and ovarian endometriosis (Ov) by immunohistochemistry. Preferential expression of both proteins was observed in the glandular and luminal epithelial cells of the eutopic endometrium of patients with and without endometriosis with a ~2.5-fold stronger expression of MT3-MMP compared to MT2-MMP. We did not observe any differences during menstrual cycling and in eutopic endometrium of patients with and without endometriosis. Similarly, eutopic endometrium and adenomyotic tissue with and without endometriosis showed similar protein levels of MT2-MMP and MT3-MMP. In contrast, MT2-MMP and MT3-MMP protein was decreased in ectopic compared to eutopic endometrium and adenomyosis. The similar expression of MT2-MMP and MT3-MMP in eutopic endometrium in patients with and without endometriosis in contrast to the impaired expression in ectopic endometrium suggests that alterations occur after and not before endometrial implantation possibly by distinct interactions with the different environments. The differential protein expression of MT2/3-MMP in adenomyosis compared to endometriosis might suggest a different pathogenesis pathway for the two diseases.
Keywords: adenomyosis; endometriosis; endometrium; membrane type-2 matrix metalloproteinase; membrane type-3 matrix metalloproteinase.