Intestinal trefoil factor induces decay-accelerating factor expression andenhances the protective activities against complement activation in intestinal epithelial cells

Mucosal damage induces a massive influx of serum complement components into the lumen. The epithelium produces a number of factors that can potentiall y ameliorate injury including intestinal trefoil factor (ITF), a small prot ease-resistant peptide produced and secreted onto the mucosal surface by go blet cells, and decay-accelerating factor (DAF), a protein produced by colu mnar epithelium which protects the host tissue from autologous complement i njury. However, coordination of these intrinsic defensive products has not been delineated. DAF protein and mRNA expression were evaluated by immunobl otting and Northern blotting, respectively. NF-kappaB-DNA binding activity and DAF promoter activity were assessed by an electrophoretic gel mobility shift assay and a reporter gene luciferase assay, respectively. ITF induced a dose- and time-dependent increase in DAF protein and mRNA expression in human (HT-29 and T84) and rat (IEC-6) intestinal epithelial cells. In diffe rentiated T84 cells grown on cell culture inserts, basolateral stimulation with ITF strongly enhanced DAF expression, but apical stimulation had no ef fects. The C3 deposition induced by complement activation was significantly blocked by the treatment with ITF. In HT-29 cells, ITF increased the stabi lity of DAF mRNA. ITF also enhanced the promoter activity of the DAF gene v ia NF-kappaB motif and induced activation of NF-kappaB-DNA binding activity . ITF promotes protection of epithelial cells from complement activation vi a up-regulation of DAF expression, contributing to a robust mucosal defense .