Human tear fluid protects against Pseudomonas aeruginosa keratitis in a murine experimental model.

Pseudomonas aeruginosa keratitis is an acute sight-threatening infection. We previously reported that human tear fluid could protect individual human corneal epithelial cells in vitro against invasion by and cytotoxicity due to clinical and laboratory isolates of P. aeruginosa and that the protective mechanism was independent of bacteriostatic activity.

Mutation of lasA and lasB reduces Pseudomonas aeruginosa invasion of epithelial cells.

Pseudomonas aeruginosa is an opportunistic bacterial pathogen implicated in a variety of devastating conditions. Its flexibility as a pathogen is attributed to a myriad of virulence factors and regulatory elements that respond to prevailing environmental conditions. ExoS and ExoT are type III secreted effector proteins, regulated by the transcriptional activator ExsA, that can inhibit invasion of epithelial cells by cytotoxic strains of P.

Modification of Pseudomonas aeruginosa interactions with corneal epithelial cells by human tear fluid.

Both cytotoxic and invasive strains of Pseudomonas aeruginosa can damage corneal epithelial cells in vitro, but neither can infect healthy corneas in vivo. We tested the hypothesis that whole human tear fluid can protect corneal epithelia against P. aeruginosa virulence mechanisms.