Purpose: In cornea matrix metalloproteinases (MMPs) are upregulated during the degradation of epithelial and stromal tissues. We investigated the levels, degree of activation, and molecular forms of MMP-2, -9 -8 and -13 and their tissue inhibitors TIMP-1 and TIMP-2 in tear fluid of patients with climatic droplet keratopathy (CDK).
Methods: 17 patients with CDK and 10 control subjects living in Argentine Patagonia received a complete eye examination . MMPs and TIMP-1/2 were determined by immunofluorometric assay (IFMA), gelatin zymography and Western immunoblot analysis in reflex tear samples.
Results: 14/17 patients had a bilateral disease. Cornea had severe hypoesthesia in advanced cases. The MMPs detected existed mostly in their latent forms. The levels of MMP-9 and MMP-2 were found to be elevated in CDK patients; there was no significant difference in the level of MMP-13, whereas latent and active polymorphonuclear neutrophil-type MMP-8 levels were significantly enhanced in control subjects. TIMPs were found to be mostly in their complex (>50 kDa) forms. Significantly augmented MMP-9 and -2/free TIMP ratios were found in CDK patients.
Conclusion: The enhanced MMP-2 and -9 levels found in CDK patients suggest that these enzymes play a role in corneal scarring in this disease. Elevated levels of PMN-type MMP-8 may reflect defensive role of this MMP in inflammatory reactions associated with recurring corneal traumas. Overall, MMPs and TIMPs are involved in both tissue destruction and host protection in CDK.
