title: Pseudomonas aeruginosa MucD protease mediates keratitis by inhibiting neutrophil recruitment and promoting bacterial survival.
abstract: OBJECTIVE
  Pseudomonas aeruginosa is a leading pathogen of blinding keratitis worldwide. In this study, the role of the serine protease in the pathogenesis of P. aeruginosa keratitis in the mouse cornea was investigated by comparing the parent and rescue strains.
  
  
  METHODS
  Cornea of C57BL/6 mice were infected with P. aeruginosa strain PAO1, serine protease (MucD protease or PA3535) mutants (ΔmucD or ΔPA3535), or a complemented strain. Corneal virulence was evaluated by determining clinical scores and bacterial enumeration. A myeloperoxidase assay was performed to determine the number of polymorphonuclear (PMN) cells infiltrating the cornea. An ELISA was used to quantify inflammatory cytokines and chemokines in the cornea.
  
  
  RESULTS
  The clinical score and bacterial numbers in eyes infected with ΔmucD were significantly lower than in those infected with PAO1, ΔPA3535, or the MucD rescue strain after 48 hours (P < 0.001). A larger number of infiltrating PMN cells was observed in eyes infected with ΔmucD at 12 and 24 hours, compared with eyes infected with PAO1. IL-1β, KC, and MIP2 levels were higher in eyes infected with ΔmucD than in those infected with PAO1 after 12 hours.
  
  
  CONCLUSIONS
  The MucD protease suppressed IL-1β, KC, and MIP2 during the early stages of the infection and inhibited neutrophil recruitment in the cornea. Therefore, the MucD protease contributes significantly to the pathogenesis of keratitis. MucD protease plays a critical role in the establishment of Pseudomonas aeruginosa keratitis by facilitating evasion of the immune response.
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Toon, Ehime, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mochizuki
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Naoko
authors.initials: N
authors.lastname: Oka
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Naoki
authors.initials: N
authors.lastname: Hayashi
authors.forename: Naomasa
authors.initials: N
authors.lastname: Gotoh
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D015818:Eye Infections, Bacterial / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D005260:Female; D007150:Immunohistochemistry; D007634:Keratitis / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D020556:Neutrophil Infiltration; D009504:Neutrophils / Q000378:metabolism*; D011552:Pseudomonas Infections / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000302:isolation & purification; D012697:Serine Endopeptidases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C097649:MucD protein, Pseudomonas aeruginosa; D012697:Serine Endopeptidases
keywords: MIP-2; MucD gene; Pseudomonas aeruginosa; keratitis; neutrophil