Decreased Progesterone Receptor B/A Ratio in Endometrial Cells by Tumor Necrosis Factor-Alpha and Peritoneal Fluid from Patients with Endometriosis

Abstract

Purpose: Progesterone resistance is thought to be a major factor that contributes to progression of endometriosis. However, it is not clear what causes progesterone resistance in endometriosis. This study aimed to assess whether cytokines or peritoneal fluid can affect progesterone receptor (PR) expression in endometrial cells and to verify whether PR expression is reduced in endometriosis.

Materials and methods: The PR-B/A ratio was measured via real-time polymerase chain reaction after in vitro culture, in which endometrial cells were treated with either tumor necrosis factor-alpha (TNF-α), interleukin-1 beta, or peritoneal fluid obtained from women with advanced-stage endometriosis. Immunohistochemistry was performed to compare PR-B expression between eutopic and ectopic endometrial tissues from women with and without advanced-stage endometriosis.

Results: The PR-B/A ratio was significantly decreased by treatment with either TNF-α (p=0.011) or peritoneal fluid from women with advanced-stage endometriosis (p=0.027). Immunoreactivity of PR-B expression was significantly lower during the secretory phase than during the proliferative phase in endometrial tissues from control subjects (p<0.001). PR-B expression was significantly reduced in the eutopic endometrium (p=0.031) and ovarian endometrioma (p=0.036) from women with advanced-stage endometriosis compared with eutopic endometrium tissues from control subjects.

Conclusion: Progesterone resistance in endometriosis may be caused by proinflammatory conditions in the pelvic peritoneal microenvironment.

Keywords: Endometriosis; cytokine; endometrium; peritoneal fluid; progesterone receptor.

Fig. 1. Effects of tumor necrosis factor-alpha, interleukin-1 beta, and peritoneal fluid obtained from patients with advanced-stage endometriosis on the ratio of progesterone receptor-B (PR-B) to progesterone receptor-A (PR-A) expression in Ishikawa cells (A, B, and E) and endometrial stromal cells (C, D, and F) at 1 h and 6 h. Results on the graph are expressed as percent, where cells treated with vehicle are normalized to 100%. ^*p=0.021 and 0.011 vs. vehicle, ^†p=0.027 vs. vehicle, ^‡p=0.011 and <0.001 vs. vehicle, ^§p=0.027 vs. vehicle. Control, vehicle; T10, tumor necrosis factor-alpha 10 ng/mL; T25, tumor necrosis factor-alpha 25 ng/mL; I10, interleukin-1 beta 10 ng/mL; I25, interleukin-1 beta 25 ng/mL.

Fig. 2. Representative micrographs (A) (×200) of progesterone receptor-B immunostaining in the eutopic endometrium of the control subjects throughout the menstrual cycle and HSCOREs (B). Data of HSCOREs are expressed as mean±SEM. ^*p<0.001 vs. control, ^†p=0.001 vs. control. EP, early proliferative phase; MP, mid-proliferative phase; LP, late-proliferative phase; ES, early-secretory phase; MS, mid-secretory phase; LS, late-secretory phase; N, negative control.

Fig. 3. Representative micrographs of progesterone receptor-B immunostaining in the eutopic endometrium of the controls and patients with endometriosis (A: control subject, B: endometriosis patient) (×400) and HSCOREs (C: glandular cells, D: stromal cells). Data of HSCOREs are expressed as mean±SEM. ^*p=0.031 and <0.001 vs. control, ^†p=0.001, 0.001, and <0.001 vs. control. W, whole menstrual phases put together; P, proliferative phase; S, secretory phase; ES, early secretory phase; MS, mid-secretory phase; LS, late secretory phase.

Fig. 4. Representative micrographs of progesterone receptor-B immunostaining in the eutopic endometrium of the controls and ovarian endometrioma (A: control subject, B: ovarian endometrioma) (×400) and HSCOREs (C). Data of HSCOREs are expressed as mean±SEM. ^*p=0.036 vs. control.