Endometrial expression of LIF and its receptor and peritoneal fluid levels of IL-1α and IL-6 in women with endometriosis are associated with the probability of pregnancy

To investigate whether eutopic endometrial expression of leukaemia inhibitory factor (LIF), LIF receptor (LIFR) and glycoprotein 130 (gp130) in subfertile women with endometriosis and in healthy controls is related to the probability of spontaneous pregnancy. In addition, we aimed to study peritoneal fluid (PF) levels of interleukin (IL)-1 alpha and IL-6 in the same subsets of women. Eutopic endometrial biopsy and PF samples were taken from patients with rASRM stage I-II endometriosis and healthy controls undergoing laparoscopy. Endometrial LIF, LIFR and gp130 immunostaining and PF levels of IL-1 alpha and IL-6 were assessed. Endometrial biopsy samples were obtained again after postoperative goserelin acetate treatment and on-going pregnancies were registered during a 6-month follow-up period. Reduced endometrial staining of LIF, LIFR and gp130, unaffected by surgery and goserelin, was seen in endometriosis patients without a recorded pregnancy during the study. Elevated PF levels of IL-6 and, in particular, IL-1 alpha were detected in these patients. Reduced eutopic endometrial LIF, LIFR and gp130 protein expression may be associated with subfertility in women with minimal-mild endometriosis. Combined surgical and goserelin acetate treatment does not seem to restore the expression of these members of the IL-6 cytokine superfamily. Elevated peritoneal fluid levels of IL-1 alpha and IL-6 may further contribute to the difficulties of achieving pregnancy in these patients.