Matrix metalloproteinase expression in Macaca mulatta endometrium: Evidence for zone-specific regulatory tissue gradients

Matrix metalloproteinases (MMPs) are highly expressed in the human endometrium during menstruation, and these enzymes participate in the cyclic destruction and regeneration characteristic of the primate endometrium. To examine hormonal regulation of MMPs in vivo, we evaluated MMP expression and localization in the endometrium of ovariectomized rhesus macaques under various hormonal conditions. Although all MMPs were up-regulated by progesterone (P₄) withdrawal, their expression declined spontaneously after menstruation in the absence of P₄. Of 7 MMPs examined, only matrilysin and stromelysin-3 were suppressed any further when P₄ levels were experimentally re-elevated. MMP expression was confined to the upper functionalis zone during menstruation, but after menstrual breakdown was complete, matrilysin and the tissue inhibitor of MMPs, TIMP-1, shifted expression from the functionalis to the basalis zone in the absence of both estradiol and P₄. The spiral arteries in the functionalis, but not the basalis, were intense foci of MMP and TIMP-1 expression. Menstruation and MMP expression after P₄ withdrawal were similar in both the presence and absence of estradiol. In sum, endometrial MMPs in vivo are strongly up-regulated by P₄ withdrawal, but zone-specific tissue gradients greatly influence the pattern and degree of MMP expression.