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Role of pvdE Pyoverdine Synthesis in Pseudomonas aeruginosa Keratitis
Takashi Suzuki1,2, Sayuri Okamoto2, Naoko Oka2
1Ishizuchi Eye Clinic, Ehime, Japan.
Purpose:
Pseudomonas aeruginosa produces pyoverdine, encoded by the pvdE gene, for high-affinity iron uptake from transferrin and lactoferrin. This study investigated the contribution of pyoverdine to P. aeruginosa keratitis pathogenesis using in vitro and in vivo models.
Methods:
The P. aeruginosa strains examined were parental strain PAO1 and isogenic mutant strain pvdE (ΔpvdE) defective in pyoverdine. Bacterial growth in vitro was determined by PAO1 and ΔpvdE optical densities in Luria-Bertani (LB) broth. PAO1 or ΔpvdE (10 colony-forming units/mL) was inoculated onto cultured human corneal epithelial cells (HCECs) for 1 hour. The monolayers were examined for bacterial adhesion and invasion. In addition, the corneas of C57BL/6 mice were infected with PAO1 or ΔpvdE. Corneal virulence was evaluated by determining clinical scores and bacterial counts during infection.
Results:
The growth of PAO1 and ΔpvdE in LB broth was similar. Although adhesion of ΔpvdE onto HCECs was significantly increased compared with PAO1, the invasive capacity of ΔpvdE was significantly decreased. Clinical scores and bacterial numbers were significantly lower in ΔpvdE-infected eyes compared with PAO1-infected eyes at 6, 24, and 48 hours (P < 0.001). ΔpvdE was not detected in mouse corneas and did not induce corneal opacity at 6, 24, or 48 hours.
Conclusions:
ΔpvdE lost invasive ability toward HCECs. Moreover, ΔpvdE did not cause keratitis in vivo. Thus, pvdE pyoverdine synthesis has critical roles in proliferation and invasion on ocular surfaces and could be a target for prevention of P. aeruginosa keratitis.
Insights
Pyoverdine, essential for Pseudomonas aeruginosa iron uptake, is crucial for eye infections. A pyoverdine-deficient mutant showed reduced invasion and virulence, suggesting pyoverdine as a target for keratitis prevention.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Pseudomonas aeruginosa utilizes pyoverdine for iron acquisition from host proteins.
- Pyoverdine is synthesized via the pvdE gene and is critical for high-affinity iron uptake.
- The role of pyoverdine in P. aeruginosa keratitis pathogenesis remains to be fully elucidated.
Purpose of the Study:
- To investigate the contribution of pyoverdine to P. aeruginosa keratitis pathogenesis.
- To evaluate the role of the pvdE gene in bacterial virulence and ocular surface infection.
Main Methods:
- Comparison of wild-type PAO1 and isogenic pyoverdine-deficient mutant (ΔpvdE) strains of P. aeruginosa.
- In vitro assessment of bacterial growth, adhesion, and invasion of human corneal epithelial cells (HCECs).
- In vivo evaluation of corneal virulence in C57BL/6 mice, assessing clinical scores and bacterial counts.
Main Results:
- Bacterial growth in vitro was similar between PAO1 and ΔpvdE.
- ΔpvdE exhibited increased adhesion but significantly decreased invasive capacity in HCECs.
- ΔpvdE-infected eyes showed significantly lower clinical scores and bacterial counts compared to PAO1-infected eyes.
Conclusions:
- Pyoverdine synthesis via pvdE is essential for P. aeruginosa invasion of corneal epithelial cells.
- The ΔpvdE mutant did not cause keratitis in a mouse model, indicating pyoverdine's critical role in ocular pathogenesis.
- Pyoverdine represents a potential therapeutic target for preventing P. aeruginosa keratitis.
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