Corticosteroid and doxycycline suppress MMP-9 and inflammatory cytokine expression, MAPK activation in the corneal epithelium in experimental dry eye

Exp Eye Res. 2006 Sep;83(3):526-35. doi: 10.1016/j.exer.2006.02.004. Epub 2006 Apr 27.


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.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / therapeutic use*
  • Depression, Chemical
  • Doxycycline / therapeutic use*
  • Dry Eye Syndromes / drug therapy*
  • Dry Eye Syndromes / enzymology
  • Dry Eye Syndromes / immunology
  • Epithelium, Corneal / drug effects
  • Epithelium, Corneal / enzymology*
  • Epithelium, Corneal / immunology
  • Glucocorticoids / therapeutic use*
  • Immunohistochemistry
  • Interleukin-1 / analysis
  • JNK Mitogen-Activated Protein Kinases / analysis
  • MAP Kinase Signaling System / drug effects
  • Matrix Metalloproteinase 9 / analysis
  • Methylprednisolone / therapeutic use*
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Confocal
  • Mitogen-Activated Protein Kinases / analysis
  • Models, Animal
  • Permeability / drug effects
  • Scopolamine
  • Tumor Necrosis Factor-alpha / analysis
  • p38 Mitogen-Activated Protein Kinases / analysis


  • Anti-Inflammatory Agents
  • Glucocorticoids
  • Interleukin-1
  • Tumor Necrosis Factor-alpha
  • Scopolamine
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Matrix Metalloproteinase 9
  • Doxycycline
  • Methylprednisolone