Abstract
Purpose:
Pseudomonas aeruginosa produces pyoverdin for high-affinity iron uptake from transferrin and lactoferrin. However, little is known about a role of pyoverdin in keratitis. This study was designed to investigate the possible contribution of pyoverdin in the pathogenesis of P. aeruginosa keratitis using in vitro and in vivo model.
Methods:
The strains used were P. aeruginosa parental strain (PAO1) and isogenic P. aeruginosa mutant defective in pyoverdin because of mutation in the pvdE gene (ΔpvdE). Experiment1: Bacterial growth in vitro was measured by determining the optical density of both PAO1 and ΔpvdE in Luria-Bertani (LB) broth. Either of PAO1 or ΔpvdE (108CFU/ml) was inoculated onto human cultured corneal epithelial cells (HCEC). Following incubation for 1 h, bacteria were removed and monolayers were washed. And bacterial adhesion were examined. Experiment2: Cornea of C57BL/6 mice were infected with PAO1 or ΔpvdE. Corneal virulence was evaluated by determining and comparing clinical scores and bacterial enumeration throughout the infection.
Results:
Experiment 1: The growth of PAO1 and ΔpvdE in LB broth were similar. The capacity of a pyoverdin deficient isogenic strain to attach HCEC increased, compared to PAO1 (p <0.05). Experiment 2 :The clinical score and bacterial numbers in eyes infected with ΔpvdE were significantly lower than in those infected with PAO1 at 6, 24 and 48 h (p <0.001). ΔpvdE strain was not detected from mice cornea, and could not induce corneal opacity at 6, 24 and 48 h.
Conclusions:
Although ΔpvdE had similar growth in vitro to parental strain and more ability adhesion to HCEC in vitro, it could not cause keratitis in vivo. The pyoverdin plays critical roles in proliferation on ocular surface and it could be target for prevention of P. aeruginosa keratitis.
Keywords: 664 pseudomonas •
573 keratitis •
557 inflammation