Histological characteristics and altered expression of interleukins (IL) IL-13 and IL-15 in endometria of levonorgestrel users with different uterine bleeding patterns

Abstract

To determine the relationship between uterine bleeding patterns in levonorgestrel users with endometrial histology and expression of interleukins (IL) IL-13 and IL-15. Prospective observational study. Academic research center. Questionnaires were sent to patients (n = 578) who had levonorgestrel implants concerning bleeding patterns; 35 of these patients were identified to have regular cycle (n = 13), amenorrhea (n = 8), or metrorrhagia (n = 14). Endometrial biopsies, serum, histology, and immunostaining. Endometrial histological assessment and immunostaining for IL-13 and IL-15 and for blood levonorgestrel, E2, and progesterone levels by ELISA or RIA. No correlation was found between circulating levonorgestrel, E2, or progesterone levels with the bleeding patterns, although a trend toward a lower E2 level was observed in patients with amenorrhea who had inactive endometrium. There was a direct correlation between bleeding patterns and endometrial histology, as well as IL-13 and IL-15 expression in patients with regular cycles and metrorrhagia, demonstrating secretory and proliferative endometrium, respectively. Some patients in each group were also identified as demonstrating endometritis. Endometrial histology may assist directing therapy and subsequently increasing compliance in progestin-only contraceptive users with irregular bleeding who fail to respond to standard therapies. Altered endometrial expression of IL-13 and IL-15, key cytokines in inflammatory and immune cell trafficking, may influence events, leading to irregular bleeding.