Tumour necrosis factor-α, interleukin-6 and interleukin-8 do not promote adhesion of human endometrial epithelial cells to mesothelial cells in a quantitative in vitro model

BACKGROUND: A key factor in the pathogenesis of endometriosis is the endometrial-peritoneal adhesion. To study the pathogenesis of endometriosis, a quantitative in vitro assay (QIVA) was developed to measure in vitro adhesion between human endometrial epithelial cells and mesothelial cells using commercially available cell lines. Using the QIVA, the hypothesis was tested that tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8) promote adhesion of endometrial epithelial cells to mesothelial cells. METHODS: Mesothelial cells were pre-treated with TNF-alpha, IL-6 or IL-8 in various concentrations (ranging from 0 to 1000 IU/ml) for 24 h. Confluent endometrial epithelial cells were labelled with [S-35]methionine, added to the confluent mesothelial cells and incubated for 1 h. After incubation, non-adhering cells were removed and adherent cells were solubilized and their [S-35]methionine radioactivity was counted to quantify the adherence of endometrial epithelial cells to mesothelial cells. RESULTS: The in vitro adhesion of human endometrial epithelial cells to human mesothelial cells was inhibited in a dose-dependent manner by TNF-alpha (P = 0.0007), IL-6 (P < 0.0001) and IL-8 (P = 0.0004). CONCLUSIONS: Using a quantitative in vitro adhesion assay, we were unable to confirm our hypothesis that TNF-alpha, IL-6 and IL-8 promote the in vitro adhesion between endometrial epithelial cells and mesothelial cells.