Aromatase expression in endometriotic tissues and cell cultures of patients with endometriosis.

Cytochrome P-450 aromatase is responsible for catalysing the conversion of androstendione into estrone, so its expression in endometriotic tissue could contribute to the development of endometriosis. The aims of this study were, on the one hand, to determine the presence of aromatase in eutopic and ectopic endometrium, healthy peritoneum, myometrium and leiomyomas from patients with (n = 61) and without endometriosis (n = 12) and, on the other hand, to determine the effect of peritoneal fluid (PF), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNFalpha) on aromatase activity from endometriotic stromal cells and subcutaneous adipocytes. After immunohistochemical analysis, aromatase expression was detected in the endometriotic tissue of 61% of patients, whereas the rest of the tissues, as well as those from disease-free women, were negative. Cell cultures were made to determine aromatase activity in endometriotic stromal cells and adipocytes. The addition of PF, TNFalpha and especially IL-6 (P < 0.05) stimulated the basal enzymatic activity observed in both cell types. Our findings confirm the presence of aromatase in endometriosis and probably the existence of a local estrogen production that may be stimulated by some factors such as cytokines present in the PF of these patients. Therefore, the use of aromatase inhibitors combined with immunomodulator agents could be a novel approach to be investigated in future clinical trials.