title: Matrix metalloproteinase-9 amplifies the immune response to Pseudomonas aeruginosa corneal infection.
abstract: OBJECTIVE
  The purpose of this study was to determine the role of matrix metalloproteinases (MMP) in Pseudomonas aeruginosa keratitis.
  
  
  METHODS
  Gene array and selective real-time PCR examined MMP expression in the cornea of susceptible (C57BL/6, B6) versus resistant (BALB/c) mice before and after infection; zymography tested enzyme activity for MMP-2 and -9. Clinical score, Langerhans cell (LC), and Neutrophil (PMN) quantitation were done in recombinant (r) MMP-9, antibody neutralized, and MMP-9(-/-) mice. The chemotactic potential of MMP-9 was tested in a Boyden chamber assay; light and transmission microscopy and immunostaining for collagen IV and MMP-9 were used to examine the effects and the source of MMP-9 after infection. ELISA was used to assess IL-1beta and MIP-2 levels.
  
  
  RESULTS
  Gene array (confirmed by PCR) revealed sixfold more MMP-9, and zymography showed greater enzyme activity in the infected cornea of B6 over BALB/c mice. rMMP-9 injection of BALB/c mice enhanced, whereas MMP-9 antibody neutralization in B6 mice and its absence in MMP-9(-/-) mice decreased corneal disease. MMP-9(-/-) and antibody neutralized mice had fewer LCs in cornea; rMMP-9-treated mice had more. A myeloperoxidase (MPO) assay showed a similar pattern for PMN. MMP-9 was not chemotactic for LC or PMN. The basement membrane was more intact in MMP-9(-/-) over wild-type infected mice and correlated with staining for collagen IV; PMN was a source of MMP-9. IL-1beta and MIP-2 were increased in rMMP-9 but decreased in MMP-9 antibody neutralized and MMP-9(-/-) over control groups.
  
  
  CONCLUSIONS
  MMP-9 regulates immune function in cornea by proteolysis, potentiating P. aeruginosa keratitis by degrading collagen IV and upregulating chemotactic cytokines/chemokines IL-1beta and MIP-2.
authors.affiliation: Department of Anatomy/Cell Biology, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, Michigan 48201, USA.
authors.forename: Sharon A
authors.initials: SA
authors.lastname: McClellan
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Barrett
authors.forename: Shahrzad
authors.initials: S
authors.lastname: Lighvani
authors.forename: Yunfan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Dawn
authors.initials: D
authors.lastname: Richiert
authors.forename: Linda D
authors.initials: LD
authors.lastname: Hazlett
mesh_terms: D000818:Animals; D000917:Antibody Formation; D054426:Chemokine CXCL2; D018925:Chemokines / Q000378:metabolism; D002634:Chemotaxis, Leukocyte / Q000502:physiology; D024141:Collagen Type IV / Q000378:metabolism; D003320:Corneal Ulcer / Q000201:enzymology / Q000276:immunology*; D004198:Disease Susceptibility; D004797:Enzyme-Linked Immunosorbent Assay; D015818:Eye Infections, Bacterial / Q000201:enzymology / Q000276:immunology*; D005260:Female; D007113:Immunity, Innate; D007375:Interleukin-1 / Q000378:metabolism; D007801:Langerhans Cells / Q000276:immunology*; D020780:Matrix Metalloproteinase 9 / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009504:Neutrophils / Q000276:immunology*; D020411:Oligonucleotide Array Sequence Analysis; D011552:Pseudomonas Infections / Q000201:enzymology / Q000276:immunology*; D011550:Pseudomonas aeruginosa / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: D054426:Chemokine CXCL2; D018925:Chemokines; D024141:Collagen Type IV; C404915:Cxcl2 protein, mouse; D007375:Interleukin-1; D020780:Matrix Metalloproteinase 9