Matrix metalloproteinases in epithelia from human recurrent corneal erosion

PURPOSE. TO assay for the presence of matrix metalloproteinases (MMPs) in h uman corneal epithelium affected by recurrent erosion compared with that in normal corneal epithelium. METHODS. Corneal epithelial debridement samples were obtained from 13 patie nts with recurrent epithelial erosion. For control specimens, epithelia wer e obtained from healthy patients undergoing photorefractive keratectomy. Zy mography was performed on all samples to identify MMPs. Immunolocalization of MMP-2, laminin, and collagen type VII was determined in two samples with human recurrent epithelial erosion and compared with that in control epith elium. RESULTS. Twelve of 13 erosion samples showed MMP-2 enzymatic activity, one of the 12 also showed MMP-9 activity. Only one erosion sample showed no MMP enzymatic activity. All normal control specimens were negative for MMP. Im munohistochemical analysis of two recurrent erosion samples showed MMP-2 pr esence in basal cells, whereas, in normal epithelium it was not detected. O ne sample with epithelial erosion showed laminin localization in basal epit helial cells and basal lamina. Type VII collagen localized in basal epithel ial cells only in this sample. A second erosion sample showed localization of laminin and type VII collagen in basal epithelial cells only. Normal cor neal epithelium showed presence of laminin and type VII collagen in basal e pithelium and basal lamina. CONCLUSIONS. Matrix metalloproteinase-2 expression is upregulated in human epithelia affected by recurrent erosion compared with that in normal contro l samples. Immunolocalization studies suggest that this enzyme is concentra ted in basal epithelial cells where it may play an important role in degrad ation of the epithelial anchoring system and the recurrent epithelial slipp age and erosion observed in these patients.