The inner lining of the uterus, the endometrium, completely remodels in response to ovarian steroid hormones during the menstrual cycle. Endometriosis is a chronic, debilitating gynaecological disorder that affects more than 10% of women (1), with 30-50% of these women suffering from infertility (2) likely due to disruptions in hormone-driven processes critical for receptivity and embryo implantation. The underlying mechanisms of endometriosis-associated infertility remain largely unknown. Our objective was to utilise human endometrial epithelial organoids (EEO) to investigate the impact of endometriosis on the hormone-responsiveness of endometrial glands and their secreted products.
EEO derived from the eutopic endometrium of patients diagnosed with minimal-mild (stages I-II, n=6), moderate-severe (stages III-IV, n=3) and without endometriosis (control, n=3) were treated with either vehicle control, 17β-estradiol (E2), or E2 and medroxyprogesterone acetate (MPA) to mimic menstrual cycle phases. Gene expression of steroid hormone receptors PGR, ESR1 and ESR2 were examined by RT-qPCR. The basolateral secreted proteome of hormone-treated EEO was analysed by mass spectrometry.
EEO treated with E2+MPA demonstrated progesterone-mediated downregulation of PGR, resembling in vivo cycle phase-dependent expression patterns, in control patients (p<0.05) and stage I-II endometriosis (p<0.05) compared to vehicle treatment, but not in patients with stage III-IV endometriosis. 39 significantly differentially abundant proteins were identified in the basolateral secreted proteome of EEO from patients with endometriosis compared to those without endometriosis and between hormone treatments, including, CRISP3 (FC=20.39, p<0.0001), INHBB (FC=8.17, p<0.001), MGAT1 (FC=4.11, p<0.01) and WNT7A (FC=8.46, p<0.05).
EEO from endometriosis patients demonstrate an impaired response to hormones, leading to an altered steroid hormone receptor expression pattern in patients with moderate-severe endometriosis, and an aberrant secreted proteome in endometriosis. These findings are critical in determining the impact of endometriosis on the hormone-driven processes required for endometrial receptivity and embryo implantation and to develop treatments targeting endometriosis-associated infertility.