Role of prostaglandin E2 in the experimental L-carnitine-induced endometriosis-like inflammatory model

Abstract

Purpose Ectopic implantation of endometrium leading to endometriosis has been correlated with various immune and non-immune parameters. Inflammatory cytokines including IL-2, IFN-γ, TNF-α, increase in serum and peritoneal fluid of endometriotic patients, while elevated levels of prostaglandins PGE1 and PGE2 have been accused of facilitating the inflammation process. Using the experimental model of L-carnitine (L-Cn)-induced endometriosis, the aim of this study was to explore the role of PGE1 and PGE2 in endometriosis development and define whether L-Cn had a direct effect on endometrial cells. Methods During treatment with L-Cn, experimental mice were injected with indomethacin or specific PGE1 and PGE2 analogs and their effect on the L-Cn-induced inflammatory state was examined. Primary uterine cells or human endometrial adenocarcinoma cell lines were used to assess the direct or indirect effect of L-Cn. Results The seven-day treatment of virgin females with L-Cn induced obvious endometrial abnormalities with accumulation of CD90 and CD11 cells. Administration of indomethacin alleviated some of the L-Cn-induced effects, but could not inverse the phenotype. Interestingly, 11-deoxy-PGE1 aggravated the L-Cn-induced effects, whereas 17-phenyl-trimor-PGE2 reversed them. In vitro experiments showed that the effect of L-Cn depended on the nature of endometrioma cells. L-Cn could aggravate the inflammatory state of Ishikawa-inoculated mice, but could alleviate symptoms from MFE-319 inoculated females. Conculsions Although PGE2 appeared to play a key role in the L-Cn-induced uterus inflammation, the actual role of L-Cn depends on the nature of endometrioma cells and can aggravate or protect from inflammation according to the induced regulatory pathways.