Objective: To test the hypothesis that endotoxin stimulates the release of interleukin-6 (IL-6) from intestinal epithelial cells and that this effect of endotoxin is regulated by prostaglandin E2 (PGE2).
Design: A rat intestinal crypt cell line, IEC-6, was cultured in the presence of lipopolysaccharide (LPS), 0.1 to 1.0 microgram/mL, and/or PGE2, 1 mumol/L. In other experiments, indomethacin, 20 mumol/L, was added to LPS-treated cells to block the effects of prostaglandins. Control wells contained medium alone. Levels of IL-6 were determined by the B9 murine hybridoma bioassay. Polymerase chain reaction was performed on RNA from control and LPS-treated cells to examine IL-6 message.
Results: Lipopolysaccharide and PGE2 induced IL-6 release from IEC-6 cells in a dose- and time-dependent fashion, and the substances interacted synergistically. Addition of indomethacin blunted the effect of endotoxin on IL-6 production, consistent with a stimulatory role of PGE2. Polymerase chain reaction demonstrated increased IL-6 messenger RNA in endotoxin-treated cells.
Conclusions: Endotoxin and PGE2 stimulate IL-6 production in IEC-6 cells and interact synergistically. The endotoxin-stimulated IL-6 release may be regulated at the transcriptional level.