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Expression of gelatinases A and B, and TIMPs 1 and 2 during corneal wound healing
1Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston 02114, USA.
Purpose:
To determine the expression of gelatinases A and B and the localization of tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 during the early stages of corneal wound healing in rats. METHODS. One eye each of 30 adult Sprague-Dawley rats was treated with excimer laser keratectomy; the other eye was untreated. Frozen sections of corneas obtained 6, 18, and 24 hours and 3 and 7 days after wounding were used to perform immunoconfocal microscopy and in situ hybridization.
Results:
Gelatinase B was immunolocalized to the basement membrane zone and superficial stroma, and its mRNA was exclusively localized to basal epithelial cells migrating across the wound at 18 and 24 hours and 3 days after wounding. Tissue inhibitor of metalloproteinase-1 was also immunolocalized to the basement membrane zone and superficial stroma at the same time points. Gelatinase A was immunolocalized to the epithelium and stroma of normal corneas and was predominant in the basal epithelium and superficial stroma at 3 and 7 days after wounding. In situ hybridization confirmed gelatinase A expression by the epithelial cells and the stromal keratocytes. Tissue inhibitor of metalloproteinase-2 was immunolocalized to the epithelium in normal and wounded corneas. Intense TIMP-2 labeling of the basement membrane zone was noted 3 days after wounding.
Conclusions:
Unlike gelatinase A, gelatinase B is expressed exclusively by migrating basal epithelial cells after wounding. The matrix metalloproteinase-tissue inhibitor of metalloproteinase (MMP)/TIMP systems may play an important role in the early stages of corneal wound healing after excimer laser keratectomy.