Interleukin-11, IL-11 receptorα and leukemia inhibitory factor are dysregulated in endometrium of infertile women with endometriosis during the implantation window

Interleukin (IL)-11 is essential for embryo implantation in the mouse and evidence suggests it has a role in implantation in humans. This study has evaluated immunoreactive IL-11, IL-11 receptor (R) α and leukemia inhibitory factor (LIF) in endometrium of infertile women with endometriosis (I/E) and normal fertile women (controls) during the implantation window. Endometrial biopsies from I/E (N = 7) were timed from the LH surge and were post-ovulatory days (POD) 5–10. Control biopsies (N = 8) from women were between days 19 and 24 of the menstrual cycle. Staining intensity of IL-11, IL-11Rα and LIF evaluated using semi-quantitative immunohistochemistry scores. Immunoreactive IL-11, IL-11Rα and LIF were present predominantly in glandular epithelium, while luminal epithelium showed patchy staining. All controls stained positively for IL-11, IL-11Rα and LIF in glandular epithelium. IL-11 and IL-11Rα staining was absent from glandular epithelium in cohorts of I/E. LIF staining intensity in glandular epithelium was significantly lower in I/E compared to controls. The results suggest that reduced endometrial IL-11 and/or LIF may contribute to infertility in some endometriotic women.