Lipopolysaccharide promoted proliferation of endometriotic stromal cells via induction of tumor necrosis factor a and interleukin-8 expression

Abstract

We have previously shown that the peritoneal fluid (PF) levels of tumor necrosis factor alpha (TNFa) and interleukin-8 (IL-8) were significantly higher in patients with endometriosis. We also demonstrated that TNFa action mediated by IL-8 might contribute to progression of endometriosis by promoting the growth of endometriotic cells through activation of nuclear factor-kB (NF-kB). The purpose of this study is to evaluate the effect of lipopolysaccharide (LPS) on the expression of TNFa and IL-8 protein in endometriotic stromal cells (ESC) and on their proliferation. Molecular and biological studies in human endometriotic tissues. Chocolate cyst linings of the ovaries in patients with endometriosis (n=17) were a source of endometriotic tissue. LPS exerted its effects by binding with cognate receptor toll-like receptor 4 (TLR4). We therefore examined the expression of TLR4 in the ESC by RT-PCR and immucytochemical stainings. We determined the effect of LPS, IL-8 antisense oligonucleotide (AS) and NF-kB inhibitor on production of TNFa and IL-8 using ELISA. We examined the effects of IL-8 AS and NF-kB inhibitor on LPS-promoted ESC proliferation by BrdU assay. The gene and protein expression of TLR4 in cultured ESC was observed by RT-PCR and immunocytochemical staining. LPS-stimulated ESC produced significant amounts of TNFa and IL-8 in a dose-dependent fashion. Adding LPS promoted ESC proliferation. Anti-TNFa and anti-IL-8 antibody inhibited the stimulatory effects of LPS. IL-8 AS and NF-kB inhibitor significantly decreased LPS-induced IL-8 protein production and LPS-induced proliferation. LPS, bacterial endotoxin, promoted proliferation of ESC by enhancing IL-8 expression via TNFa and NF-kB activation. We suggest for the first time that pelvic inflammation may promote the progression of endometriosis.