title: Exposure of human corneal epithelial cells to contact lenses in vitro suppresses the upregulation of human beta-defensin-2 in response to antigens of Pseudomonas aeruginosa.
abstract: Bacterial keratitis is a sight-threatening complication of contact lens wear, and Pseudomonas aeruginosa is a commonly isolated pathogen. The mechanisms by which lenses predispose the cornea to P. aeruginosa infection are unknown. Corneal epithelial cells express numerous innate defenses, some of which have bactericidal effects against P. aeruginosa. One of these is human beta-defensin-2 (hBD-2), which is upregulated in response to lipopolysaccharide or flagellin antigens. We hypothesized that prior exposure of corneal epithelia to a contact lens would interfere with upregulation of hBD-2 in response to P. aeruginosa. A novel in vitro model was used in which cultured human corneal epithelial cells were exposed to a hydrophilic contact lens for up to 3.5 days prior to challenge with a culture supernatant of P. aeruginosa antigens for 6h. Without prior lens exposure, the supernatant caused >2-fold upregulation of hBD-2 mRNA message and expression of hBD-2 peptide. Prior contact lens exposure blocked this upregulation without obvious effects on cell health. Western immunoblot and luciferase reporter studies showed that Pseudomonas-induced hBD-2 upregulation involved MyD88, c-Jun N-terminal kinase and both AP-1 and NF-kappaB transcription factors. Contact lenses did not affect surface expression of Toll-like receptor-2, -4 or -5, but did block antigen activation of AP-1, but not NF-kappaB, transcription factors. These data show that contact lenses can interfere with epithelial defense responses to bacterial antigens in vitro, and if translated in vivo, could help predispose the cornea to infection.
authors.affiliation: School of Optometry, University of California, Berkeley, CA 94720, USA.
authors.forename: I A
authors.initials: IA
authors.lastname: Maltseva
authors.forename: S M J
authors.initials: SM
authors.lastname: Fleiszig
authors.forename: D J
authors.initials: DJ
authors.lastname: Evans
authors.forename: S
authors.initials: S
authors.lastname: Kerr
authors.forename: S S
authors.initials: SS
authors.lastname: Sidhu
authors.forename: N A
authors.initials: NA
authors.lastname: McNamara
authors.forename: C
authors.initials: C
authors.lastname: Basbaum
mesh_terms: D000890:Anti-Infective Agents / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D002478:Cells, Cultured; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology; D004847:Epithelial Cells / Q000276:immunology; D019573:Epithelium, Corneal / Q000276:immunology / Q000378:metabolism*; D005136:Eye Proteins / Q000276:immunology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000276:immunology; D008954:Models, Biological; D053594:Myeloid Differentiation Factor 88 / Q000276:immunology; D016328:NF-kappa B / Q000276:immunology; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D012333:RNA, Messenger / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015854:Up-Regulation / Q000276:immunology; D023083:beta-Defensins / Q000032:analysis / Q000276:immunology*
chemical_list: D000890:Anti-Infective Agents; D000942:Antigens, Bacterial; C106641:DEFB4A protein, human; D005136:Eye Proteins; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D023083:beta-Defensins