The Effects of 2% Rebapimide Ophthalmic Solution on the Corneal Epithelial Barrier Function of the Superoxide Dismutase-1 (Sod1) Knockout Mice

Abstract

Purpose: SOD-1 knock out mouse has been reported to be a model for age related dry eye disease. We investigated the alterations in the corneal epithelial barrier function in the Sod1^-/- in comparison to the wild type mice with 2% rebamipide eye drop application.

Methods: Ten eyes of 5 Sod1^-/- male mice with C57BL/background and 12 eyes of 6 C57BL6 strain wild-type male mice were examined at 50 weeks before and after application of 2% rebamipide eye drops q.i.d. for 2 weeks in this study. Tear film stability and corneal epithelial damage was evaluated by fluorescein and Lissamine green(LG) stainings. Anterior segment photography was carried out before and after eye drop instillations. Aqueous tear quantity was measured with phenol-red-impregnated cotton threads without anesthesia. Animals were sacrificed and the whole globe specimens underwent HE as well as beta catenin and ZO-1(zonula occludens)immunohistichemistry stainings. Quantitative Real Time-PCR for beta catenin and ZO-1 mRNA expression was also performed. Electron microscopy was also performed before and after rebamipide eye drop application. All studies were performed in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.

Results: The mean pre-treatment fluorescein and LG staining scores were significantly higher and the mean BUT was significantly lower in the Sod1^-/- mice compared to the WT mice. These scores improved significantly in the Sod1^-/- mice after 2 weeks of rebamipide treatment (p<0.01). The beta catenin and ZO-1 staining intensity and m RNA expressions increased significantly with 2% rebamipide treatment (p<0.01). Electron microscopy revealed improvement of epithelial barrier function after 2 weeks of treatment.

Conclusions: The corneal ocular surface disease in the Sod1^-/-mice was associated with tear instability, ocular surface epithelial damage, disruption of corneal epithelial barrier as evidenced by decreased beta catenin and ZO-1 expressions. Two week application of 2% Rebamipide eye drops was found to be effective in terms of improvement of corneal epithelial barrier in the SOD-1 KO mice.