Altered expression of interleukin-18 in the ectopic and eutopic endometrium of women with endometriosis

OBJECTIVE: This study has investigated the expression of interleukin (IL)-18 in the eutopic and ectopic endometrium of women with endometriosis and the role of IL-18 on the pathogenesis of endometriosis. METHODS: Endometriotic tissue specimens and endometrium specimens were obtained from patients with endometriosis. IL-18 protein was determined by immunohistochemical analysis. Expression levels of IL-18 mRNA were analyzed by reverse transcriptase (RT)-PCR. RESULTS: IL-18 was detected in the glandular epithelial and stromal cells of eutopic and ectopic endometrium. RT-PCR analysis showed that endometrial IL-18 mRNA expression levels were significantly higher at the secretory phase than the proliferative phase in normal women, but not in patients with endometriosis. IL-18 mRNA expression levels were lower in the ectopic endometrium than in the eutopic endometrium of women with endometriosis. IL-18 mRNA levels in both ectopic and eutopic endometrium of patients with endometriosis were lower than in endometrium of women without endometriosis. CONCLUSION: Ectopic and eutopic endometrial IL-18 was down-regulated in women with endometriosis, suggesting that IL-18 might play a pathogenic role in the formation of endometriosis.