Pseudomonas aeruginosa quorum-sensing signal molecules induce IL-8 production by human corneal epithelial cells

The aim of the present study was to evaluate whether the quorum-sensing molecules of Pseudomonas aeruginosa could induce the production of interleukin-8 (IL-8) in human corneal epithelial (HCE) cells in vitro.

A confluent monolayer of immortalized HCE cells was treated with 12.5 to 50 microM n-(3-oxododecanoyl)-L-homoserine lactone (OdDHL) or n-butanoyl-L-homoserine lactone (BHL) for 18 hours, or challenged with a wild-type P. aeruginosa PAO1 and its quorum-sensing mutants PAO-JP1 (lasI(-)), PDO100 (rhlI(-)), and PAO-JP2 (lasI(-)/rhlI(-)) for 1 hour. The levels of IL-8 in the culture supernatants were determined using an enzyme-linked immunosorbent assay.

OdDHL stimulated the production of IL-8 in HCE cells in a dose dependent manner. IL-8 production was seen with low concentrations of BHL (12.5 and 25 microM), but not at higher levels. There was significantly less IL-8 production in the HCE cells challenged with quorum-sensing mutants compared with the wild-type strain PAO1-challenged cells.

These findings suggest that quorum-sensing signal molecules OdDHL and BHL may directly contribute to the induction of the inflammatory response in Pseudomonas keratitis.