IL-8 production in human lung fibroblasts and epithelial cells activated by the Pseudomonas autoinducer N-3-oxododecanoyl homoserine lactone is transcriptionally regulated by NF-kappa B and activator protein-2

The destructive pulmonary inflammation associated with Pseudomonas aerugino sa colonization is caused, in part, by the production of the chemokine IL-8 , which recruits neutrophils; into the lung. The Pseudomonas autoinducer, N -3-oxododecanoyl homoserine lactone (3-O-C12-HSL), is a small lipid-soluble molecule that is essential in the regulation of many P. aeruginosa virulen ce factors, but little is known about how it affects eukaryotic cells. In t his report we demonstrate that 3-O-C12-HSL is a potent stimulator of both I L-8 mRNA and protein from human fibroblasts and epithelial cells in vitro. The IL-8 produced from these 3-O-C12-HSL-stimulated cells was found to be f unctionally active by inducing the chemotaxis of neutrophils. To determine a mechanism for this IL-8 induction, deletion constructs of the IL-8 promot er were examined. It was found that the DNA region between nucleotides -148 1 and -546 and the transcription factor NF-KB were essential for the maxima l induction of IL-8 by 3-O-C12-HSL. This was confirmed by EMSAs, where 3-O- C12-HSL induced a shift with both AP-2 and NF-KB consensus DNA. The activat ion of NF-kappaB and subsequent production of IL-8 were found to be regulat ed by a mitogen-activated protein kinase pathway. These findings support th e concept that the severe lung damage that accompanies P. aeruginosa infect ions is caused by an exuberant neutrophil response stimulated by 3-O-C12-HS L-induced IL-8. Understanding the mechanisms of 3-O-C12-HSL activation of l ung structural cells may provide a means to help control lung damage during infections with P. aeruginosa.