NF-κB mediates up-regulation of CFTR gene expression in Calu-3 cells by interleukin-1β

Inflammation of the airways is a major feature of the inherited disease cystic fibrosis. Previous studies have shown that the pro-inflammatory cytokines tumor necrosis factor alpha and interferon gamma reduce the expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene (CFTR) in HT-29 and T84 cells by acting post-transcriptionally. We have investigated the effect of the pro-inflammatory peptide interleukin 1 beta (IL-1 beta) on the expression of the CFTR in Calu-3 cells, IL-1 beta increased the production of CFTR mRNA in a dose- and time-dependent manner. Its action was inhibited by inhibitors of the NF-kappaB pathway, including N-acetyl-L-cysteine, pyrrolidine dithiocarbamate, and a synthetic cell-permeable peptide containing the NF-kappaB nuclear localization signal sequence. Gel shift analysis showed that IL-1 beta activated NF-kappaB in Calu-3 cells, and transfection experiments using p50 and RelA expressing vectors showed that exogenous transfected NF-kappaB subunits increased the concentration of CFTR mRNA. Gel shift analysis with antibody supershifting also showed that IL-1 beta caused the binding of NF-kappaB to a kappaB-like response element at position -1103 to -1093 in the CFTR 5'-flanking region. Transfection experiments using -2150 to +52 CFTR reporter gene constructs showed that the activity of the CFTR promoter is enhanced by exogenous transfected NF-kappaB and IL-1 beta and that this enhancement is due, at least in part, to the -1103 to -1093 kappaB site. We conclude that the intracellular signaling that; leads to increased CFTR mRNA in response to IL-1 beta in Calu-3 cells includes the binding of NF-kappaB to the -1103 kappaB element and a subsequent increase in CFTR promoter activity.