Reactive oxygen species mediate inflammatory cytokine release and EGFR-dependent mucin secretion in airway epithelial cells exposed to Pseudomonas pyocyanin

Despite the long-appreciated in vivo role of the redox-active virulence factor pyocyanin in Pseudomonas airway infections and the importance of airway epithelial cells in combating bacterial pathogens, little is known about pyocyanin's effect on airway epithelial cells. We find that exposure of bronchiolar epithelial cells to pyocyanin results in MUC2/MUC5AC induction and mucin secretion through release of inflammatory cytokines and growth factors (interleukin (IL)-1 beta, IL-6, heparin-bound epidermal growth factor, tissue growth factor-alpha, tumor necrosis factor-alpha) that activate the epidermal growth factor receptor pathway. These changes are mediated by reactive oxygen species produced by pyocyanin. Microarray analysis identified 286 pyocyanin-induced genes in airway epithelial cells, including many inflammatory mediators elevated in cystic fibrosis (granulocyte colony-stimulating factor (G-CSF), granulocyte-monocyte CSF, chemokine (C-X-C motif) ligand 1 (CXCL1), serum amyloid, IL-23) and several novel pyocyanin-responsive genes of potential importance in the infection process (IL-24, CXCL2, CXCL3, CCL20, CXCR4). This comprehensive study uncovers numerous details of pyocyanin's proinflammatory action and establishes airway epithelial cells as key responders to this microbial toxin.