Aldose reductase inhibitor counteracts the enhanced expression of matrix metalloproteinase-10 and improves corneal wound healing in galactose-fed rats

PURPOSE: We investigated the effect of an aldose reductase inhibitor (ARI) and the role of matrix metalloproteinase (MMP)-10 on recovery after corneal epithelium removal in a rat diabetic keratopathy model. METHODS: Three-week-old Sprague-Dawley rats were fed the following diets for 6 weeks: normal MF chow (MF), 50% galactose (Gal), and 50% Gal containing 0.01% ARI (Gal +ARI). The corneal epithelium was removed using n-heptanol, and the area of epithelial defects was photographed and measured every 24 h. Real-time reverse transcriptase PCR, western blotting, and immunohistochemistry were used to determine the expression profile of MMP-10 and integrin α3. RESULTS: Compared to the MF control group, the amount of galactitol in the Gal group increased approximately 200-fold, which was reduced to sevenfold by ARI treatment. The area of corneal erosion in the Gal group was significantly larger than in the MF group at 72 h and thereafter (p<0.01, unpaired t test). The expression level of MMP-10 was enhanced at both the protein and mRNA levels by exposure to a high concentration of Gal, while integrin α3 expression decreased at the protein level but remained unchanged at the mRNA level. Delayed epithelial wound healing and alterations in the expression levels of MMP-10 and integrin α3 were normalized by ARI. The corneal erosion closure rate was significantly decreased with topical recombinant MMP-10. CONCLUSIONS: These studies confirm that the increased expression of MMP-10 induced by Gal feeding is counteracted by ARI treatment and suggest a role of MMP-10 in modulating corneal epithelial wound healing.