Objective: To evaluate the local matrix metalloproteinase 1 (MMP-1), estrogen receptor (ER) alpha, and ERbeta protein expression in eutopic and dystopic tissue from patients with endometriosis and to compare the endometrial expression pattern in women with and without endometriosis.
Design: Immunohistochemical analysis of MMP-1, ERalpha, and ERbeta in paired samples of uterine and endometriotic endometrium from cycling women with endometriosis and in endometrial tissue from 37 healthy women.
Setting: Research laboratory at a medical school.
Patient(s): Thirty-seven matched samples from endometriotic and corresponding endometrial biopsies obtained during the proliferative and secretory phase. Thirty-seven endometrial biopsies obtained from healthy women during comparable cycle phases.
Intervention(s): Sampling of endometrial and endometriotic tissue.
Main outcome measure(s): Matrix metalloproteinase 1, ERalpha, and ERbeta protein expression in paraffin-embedded tissue biopsies was measured by IHC.
Result(s): In patients with endometriosis, epithelial and stromal cells from endometriotic lesions both express significantly higher levels of MMP-1 and lower levels of ERalpha than corresponding cells in uterine endometrium. Endometriotic epithelium also expresses higher levels of ERbeta than of ERalpha. In both endometrial glands and corresponding endometriotic epithelium, the distribution of MMP-1 is correlated with ERbeta. No significant differences in endometrial ERalpha, ERbeta, or MMP-1 expression could, however, be detected when patients with endometriosis and healthy controls were compared.
Conclusion(s): We have shown that MMP-1 and ERbeta are coexpressed and up-regulated in endometriotic lesions, whereas local ERalpha expression is down-regulated. The altered ERbeta/ERalpha ratio in endometriotic glands suggests that estrogenic effects on MMP-1 are primarily mediated via ERbeta, and the local control of MMP-1 in eutopic endometrium is not different from that observed in healthy cycling women.