IL-6 PRODUCTION IN HUMAN INTESTINAL EPITHELIAL-CELLS FOLLOWING STIMULATION WITH IL-1-BETA IS ASSOCIATED WITH ACTIVATION OF THE TRANSCRIPTION FACTOR NF-KAPPA-B

Recent studies suggest that interleukin-1 beta (IL-1 beta) stimulates interleukin-6 (IL-6) production in human intestinal epithelial cells, but the intracellular mechanisms of this response are not known. In ot her reports, the nuclear factor-kappa B (NF-kappa B) regulated IL-6 pr oduction in certain cell types. We tested the hypothesis that IL-6 pro duction in the enterocyte is associated with activation of NF-kappa B. Caco-2 cells, a human intestinal epithelial cell line, were grown in tissue culture whereafter they were treated with IL-1 beta (0.5 ng/ml) . Cells were preincubated with pyrrolidine dithicucarbamate (PDTC; 10- 500 mu M), tosyl-lys-chloromethyllretone (TLCK; 10-500 mu M), or genis tein (25-75 mu M), all of which are known inhibitors of NF-kappa B. IL -6 levels in the culture media were measured after 24 hr by enzyme-lin ked immunosorbent assay (ELISA) and IL-6 messenger RNA (mRNA) levels w ere determined after 4 hr by competitive reverse-transcriptase polymer ase chain reaction (RT-PCR). NF-kappa B activity was determined by ele ctrophoretic gel mobility shift assay (ERISA), PDTC, TLCK, and geniste in each inhibited IL-1 beta-induced IL-6 production by the Caco-2 cell s in a dose-dependent fashion. These responses were also associated wi th a decrease in IL 6 mRNA levels. There was no NF-kappa B activity in untreated cells, but the addition of IL-1 beta resulted in the activa tion of NF-kappa B as determined by EMSA. The results suggest that IL- 1 beta-induced IL-6 production in the enterocyte is associated with ac tivation of NF-kappa B. The inhibition of IL-6 production by the NF-ka ppa B inhibitors indicates that the IL-6 production is regulated by NF -kappa B, although further experiments are needed to test that hypothe sis. (C) 1997 Academic Press.