Interleukin-17 and lipopolysaccharides synergistically induce cyclooxygenase-2 expression in human intestinal myofibroblasts

Background: Colonic subepithelial myofibroblasts (SEMF) play a role in the modulation of mucosal inflammatory responses via the secretion of various inflammatory mediators. In the present study the effects of interleukin (IL)-17 and lipopolysaccharides (LPS) on cyclooxygenase (COX) expression in colonic SEMF were investigated. Methods: The expression of COX-1 and -2 proteins and mRNAs were determined by western and northern blotting, respectively. Nuclear factor (NF)-κB DNA binding activities were evaluated by electrophoretic gel mobility shift assays (EMSA). Results: The expression of COX-2 protein and mRNA was rapidly induced by the addition of IL-17 and LPS, whereas COX-1 expression was not affected by these factors. The effects of IL-17 and LPS were detected in a dose- and time-dependent manner. Furthermore, IL-17 and LPS synergistically induced COX-2 mRNA and protein expression. The EMSA demonstrated that the addition of IL-17 and LPS induced NF-κB activation within 1.5 h after stimulation, and a blockade of NF-κB activation by a recombinant adenovirus containing a stable form of IκBa markedly reduced the IL-17- and LPS-induced COX-2 mRNA expression. In these cells, the expression of Toll-like receptor (TLR)-4, which is a cellular receptor for LPS, was detected. Conclusion: Interleukin-17 and LPS play an important role in the induction of COX-2 in SEMF. These findings suggest that COX-2 expression and prostaglandin synthesis might be regulated by both T-cell-derived factor (IL-17) and bacterial products (LPS) in the inflamed mucosa.