Background: Endometrial breakthrough bleeding is characterized by an inflammatory reaction and increased production of proinflammatory mediators, one of which may be epithelial neutrophil-activating peptide-78 (ENA-78), a chemokine with neutrophil-activating properties.
Methods and results: We therefore investigated the endometrial expression of ENA-78 in Norplant users as progestin-only contraceptive with various bleeding patterns (n=35) as compared with non-users with a normal menstrual cycle (n=55). The endometrial stromal cells (ESCs) were the major site of ENA-78 expression with the highest levels found during the secretory phase. The expression of ENA-78 was increased in Norplant users with irregular bleeding as compared with those with regular cycles and amenorrhoea. The levels of ENA-78 detected in uterine washes and sera after the use of Norplant for 3-6 months (n=25) increased compared with baseline (P < 0.05). These levels did not significantly change in Norplant users who received doxycycline (Dox) therapy (25 mg/twice daily for 6 months) when measured midway through or at the conclusion of study when compared with the baseline (n=25). Treatments with medroxyprogesterone acetate (MPA) and tumour necrosis factor-alpha (TNF-alpha) (25 ng/ml), but not 17beta-estradiol (E2) or E2 + MPA (10(-8) M), representing endometrium exposed to contraceptive and inflammatory conditions, respectively, increased the levels of ENA-78 production by ESCs, and this was reduced by co-treatments with Dox (25 microg/ml) (P < 0.05).
Conclusions: The endometrial production of ENA-78 is altered in progestin-only contraceptive users experiencing breakthrough bleeding and is regulated by MPA and TNF-alpha in ESCs. Although Dox therapy did not alter uterine ENA-78 secretion, its suppression in ESCs suggests that Dox, acting site-specifically and through an anti-inflammatory mechanism, may influence the outcome of breakthrough bleeding in contraceptive users.