LIF and LIF‑R expression in the endometrium of fertile and infertile women: A prospective observational case‑control study.

The aim of the present study was to determine the expression of leukemia inhibitory factor (LIF) and LIF receptor (LIF‑R) in the endometrium of fertile and infertile women during the implantation window. A prospective study was conducted between March 2013 and March 2015 at Iakentro, Infertility Treatment Center (Thessaloniki, Greece) and the 3rd Department of Obstetrics and Gynecology, Aristotle University of Thessaloniki (Thessaloniki, Greece). The patient group consisted of women diagnosed with infertility, whereas the control group consisted of women who had delivered at least one live newborn (fertile women). An endometrial biopsy was obtained using a Pipelle on day 7 or 8 post‑ovulation, and the expression of LIF and LIF‑R was assessed by immunohistochemistry in epithelial and stromal cells. Primary outcomes included positive cellular percentage, staining intensity and H‑score. P<0.05 was considered to indicate a statistically significant difference. Overall, 45 women were included in the present analysis (15 fertile women and 30 infertile women). Mean age was 32.8±6.0 years for the fertile group, and 37.6±3.7 for the infertile group. LIF and LIF‑R expression was significantly reduced in the epithelial cells of infertile women (P=0.05 and P=0.006, respectively). However, no significant differences were detected with regards to the expression of LIF in stromal cells (P=0.95). In addition, LIF‑R expression was relatively higher in the stromal cells of the fertile group; however, the difference did not reach statistical significance (P=0.10). In conclusion, endometrial expression of LIF and LIF‑R is significantly reduced in the epithelial cells of infertile women. Expression patterns of LIF‑R in stromal cells require further research in order to achieve definitive results.