Effects of topical nonsteroidal antiinflammatory drugs on the expression of matrix metalloproteinases in the cornea

To assess the effects of nonsteroidal antiinflammatory drug (NSAID) eyedrops on the expression of matrix metalloproteinases in corneal tissue. Ocular Microbiology and Immunology Laboratory, Refractive Surgery Research Laboratory, The Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, USA. Seventy rats were divided into 2 groups: intact and debrided epithelium. Uniform central corneal epithelial defects were created in the right eye of the debrided corneal group. Each group was divided into 4 subgroups, each receiving 1 of the following eyedrops or artificial tears: The 3 NSAIDs were diclofenac sodium 0.1% (Falcon® or Voltaren®) and preservative-free ketorolac 0.5% (Acular® PF). The artificial tears were carboxymethylcellulose sodium 0.5% (Refresh Plus® PF). The eyedrops were administered 4 times a day for 1 week. The rats were killed on days 2 and 7. The corneas were excised and processed for immunohistochemical staining, Western blot assay, and zymography studies to determine the localization of the production of the following matrix metalloproteinases (MMPs): MMP-1, MMP-2, MMP-8, and MMP-9. Matrix metalloproteinase-1, MMP-8, and MMP-2 were detected in rat corneas at 48 hours in the debrided and intact epithelium groups treated with NSAID eyedrops. The MMP-1 and MMP-8 expression levels were higher in intact corneas in the diclofenac sodium groups than in the ketorolac and artificial tears groups. The expression was localized mostly in the epithelial cells and occasionally in keratocytes. This study provides preliminary evidence that topical application of some NSAIDs can induce the early expression of MMP-1, MMP-2, and MMP-8 in the cornea, suggesting that MMPs play a role in the corneal cytotoxicity of certain NSAIDs.