[Involvement of MAPKs and NF-kappaB pathways in Pseudomonas pyocyanin-induced interleukin-8 expression by human airway epithelial cells].
To investigate the molecular mechanisms of signaling transduction by which Pseudomonas pyocyanin induces IL-8 expression in human airway epithelial cells, A549 and SPC-A-1 cells were challenged with P. aeruginosa conditioned medium or pyocyanin. Chemokine interleukin-8 (IL-8) release from the challenged cells was measured by ELISA, and Western blot was performed to analyze the degradation of IkappaB-alpha and the phosphorylation of MAPKs (mitogen-activated protein kinases) in the extracts from cells stimulated with pyocyanin. Both of P. aeruginosa conditioned medium and pyocyanin remarkably increased IL-8 expression by human airway epithelial cells. Degradation of IkappaB-alpha was found shortly after A549 cells were stimulated with pyocyanin. Western hybridization analysis also demonstrated that pyocyanin caused phosphorylation of MAPKs including ERK1/2, p38 and JNK in A549 cells. Pretreatment of A549 cells with U0126 (10 micromol/L), a selective inhibitor of MEK1/2 (ERK1/2 kinase) or with SB203580 (10 micromol/L), a specific inhibitor of p38 MAPK, diminished the pyocyanin-induced IL-8 production. These findings suggest that Pseudomonas pyocyanin can increase IL-8 expression by human airway epithelial cells through MAPKs signaling pathways and the activation of NF-kappaB is also involved in this process.