Doxycycline alters the expression of inflammatory and immune-related cytokines and chemokines in human endometrial cells: implications in irregular uterine bleeding.

BACKGROUND Increased production of pro-inflammatory mediators is considered central in the manifestation of events leading to irregular uterine bleeding in progestin-only contraceptive users. Evidence suggests that in addition to its antimicrobial property, doxycycline (Dox) acts as an anti-inflammatory agent mainly through the suppression of pro-inflammatory mediators. METHODS We tested this hypothesis in the endometrial environment using an in vitro model consisting of isolated human endometrial glandular epithelial and stromal cells and a human endometrial surface (HES) epithelial cell line cultured under defined conditions. RESULTS We found that Dox at doses ranging from 1 to 100 microg/ml had a limited growth-inhibitory effect on these cells, whereas Dox in a dose-dependent manner inhibited the production of tumour necrosis factor-alpha (TNF-alpha). Using multiplex cytokine/chemokine protein analysis to test a broader range of Dox activity, we found that Dox at 25 microg/ml either alone or in the presence of 17beta-estradiol (E2), medroxyprogesterone acetate (MPA) and E2+MPA (10(-8) M) as well as TNF-alpha (25 ng/ml), representing the endometrial environment exposed to contraceptives as well as inflammatory conditions, respectively, altered the production of multiple cytokines and chemokines as compared with untreated controls. These actions of Dox occurred in cell-, ovarian steroid- and cytokine/chemokine-dependent manners. Although Dox reduced the regulatory action of steroids on the production of these cytokines/chemokines, it was less effective on TNF-alpha-treated cells. CONCLUSIONS The results support the hypothesis that Dox, by modulating the endometrial expression of multiple inflammatory-related cytokines/chemokines in a cell- and cytokine/chemokine-dependent manner, may have a therapeutic potential in patients experiencing irregular uterine bleeding, in particular in progestin-dominant contraceptive users.