A mouse model for the study of recurrent corneal epithelial erosions: α9β1 integrin implicated in progression of the disease

Abstract

PURPOSE. TO describe an in vivo mouse model for the study of recurrent corneal erosion syndrome (RCES) in mice and to characterize the changes in α9 integrin expression during wound healing. METHODS. Corneal epithelial debridement wounds of two sizes (1.5 and 2.5 mm) were made on the ocular surface of BALB/c mice and were evaluated at various times after wounding. Corneas were processed either as whole mounts and stained with propidium iodide and an antibody against α9 integrin or for bromodeoxyuridine analyses of cell proliferation. A separate study involved analyses of corneal wound healing over time in individual mice with large and small debridement wounds. Mice were anesthetized once per week and their corneas stained with fluorescein to assess the quality of the corneal epithelium. After 6 weeks, mice were killed and eyes processed for study by immunofluorescence in either whole mounts or frozen sections. RESULTS. Whole mount confocal microscopy showed open wounds on the ocular surface of mice at 1 and 2 weeks after large wounds were created, but not after small wounds. In addition, α9 integrin was upregulated during healing, and changes were observed in α9 integrin localization at the limbus with large wounds but not with small wounds. Although only 1 of 16 corneas with small wounds had erosions at 1 and 2 weeks, 11 of 16 with large wounds had erosions. However, by 6 weeks, 13 of 16 eyes showed signs of erosion whether wounds were small or large. With large wounds, RCES corneas frequently showed numerous goblet cells adjacent to a limbus lacking α9 integrin. Corneas from mice with documented RCES showed both retention of α9 integrin and tenascin-C expression at the anterior stromal-epithelial interface as well as impaired relocalization of α3β1 integrin to the basement membrane zone. CONCLUSIONS. These data show that spontaneous recurrent corneal erosions occur in a mouse model after manual creation of a single wound by debridement. Differences between the healing of small (1.5 mm) and large (2.5 mm) wounds were observed. Large wounds often resulted in the presence of goblet cells on the central cornea and a loss of α9 integrin at the limbus. Small wounds never showed differences in the localization of α9 integrin at the limbus, and no goblet cells were observed in the central cornea. More studies are needed to understand the causes of erosions in these mice.