title: Corticosteroid and doxycycline suppress MMP-9 and inflammatory cytokine expression, MAPK activation in the corneal epithelium in experimental dry eye.
abstract: We investigated the effects of corticosteroid and doxycycline on expression of matrix metalloproteinase (MMP)-9 and inflammatory cytokines and activation of mitogen-activated protein kinase (MAPK) signaling pathways, c-jun N-terminal kinases (JNK), extracellular-regulated kinases (ERK) and p38, in experimental murine dry eye. Experimental dry eye (EDE) was created in C57BL6 mice, with or without or topical treatment consisting of 1% methylprednisolone, 0.025% doxycycline or balanced salt solution four times per day. MMP-9 expression in the cornea epithelia was evaluated by laser scanning confocal microscopy. Gelatinase activity in the cornea was evaluated by in situ zymography and MMP-9 activity in tear washings was evaluated by gelatin zymography. Total and phosphorylated MAPKs (JNK1/2, ERK1/2, p38) were detected by Luminex immunobead assay. Levels of MMP-9, interleukin (IL)-1alpha, IL-1beta and tumor necrosis factor (TNF)-alpha RNA transcripts were evaluated by real-time PCR. MMP-9 immunoreactivity was localized to the apical corneal epithelial cell membranes in normal control eyes. Desiccating stress significantly increased production of MMP-9 by the corneal epithelium and increased its activity in the corneal epithelium and tear fluid. Dryness also increased expression of IL-1alpha, IL-1beta and TNF-alpha mRNA and stimulated phosphorylation of JNK1/2, ERK1/2 and p38 MAPKs in the corneal epithelium. Both methylprednisolone and doxycycline reduced expression and activity of MMP-9, decreased levels of inflammatory cytokines transcripts and reduced activation of MAPKs in the corneal epithelium in response to EDE. Desiccating stress stimulates expression of MMP-9, IL-1alpha, IL-1beta and TNF-alpha mRNA , as well as activates MAPK signaling pathways in the corneal epithelium. Both corticosteroid and doxycycline suppressed this molecular stress response.
authors.affiliation: Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, 6565 Fannin Street, NC 205, Houston, TX 77030, USA.
authors.forename: Cintia S
authors.initials: CS
authors.lastname: De Paiva
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Corrales
authors.forename: Arturo L
authors.initials: AL
authors.lastname: Villarreal
authors.forename: William J
authors.initials: WJ
authors.lastname: Farley
authors.forename: De-Quan
authors.initials: DQ
authors.lastname: Li
authors.forename: Michael E
authors.initials: ME
authors.lastname: Stern
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Pflugfelder
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D003864:Depression, Chemical; D004318:Doxycycline / Q000627:therapeutic use*; D015352:Dry Eye Syndromes / Q000188:drug therapy* / Q000201:enzymology / Q000276:immunology; D019573:Epithelium, Corneal / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D005938:Glucocorticoids / Q000627:therapeutic use*; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000032:analysis; D048031:JNK Mitogen-Activated Protein Kinases / Q000032:analysis; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020780:Matrix Metalloproteinase 9 / Q000032:analysis; D008775:Methylprednisolone / Q000627:therapeutic use*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis; D023421:Models, Animal; D010539:Permeability / Q000187:drug effects; D012601:Scopolamine; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D048051:p38 Mitogen-Activated Protein Kinases / Q000032:analysis
chemical_list: D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D012601:Scopolamine; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9; D004318:Doxycycline; D008775:Methylprednisolone