Effect of topical cyclosporin a on herpetic stromal keratitis in a mouse model

Purpose: To study the effect of topical cyclosporin A on herpetic stromal keratitis (HSK) in a mouse model. Methods: The corneas of BALB/c mice were infected with herpes simplex type 1 virus. The mice were divided into 4 groups according to topical treatment methods: vehicle solution, 0.01% cyclosporin A, 0.1% cyclosporin A, and 1% cyclosporin A. The severity of stromal keratitis was graded clinically at 3, 7, 10, and 14 days after treatment. Histologic and immunohistochemical examinations were performed to analyze infiltrating inflammatory cells and T lymphocytes at 14 days after treatment. Flow cytometry was performed to count CD4(+) T cells at 14 days after treatment. Results: On day 3 after treatment, there were no significant differences in mean severity scores of HSK between the vehicle and cyclosporin A-treated groups. On days 7, 10, and 14, the severity scores in the groups treated with 0.1% or 1% cyclosporin A decreased significantly compared with the vehicle group (P < 0.05). However, the scores in the group treated with 0.01% cyclosporin A did not change up to 14 days after treatment. By histologic and immunohistochemical analysis, a significant decrease in the total number of inflammatory cells and T lymphocytes was detected in the groups treated with 0.1% or 1% cyclosporin A. Flow cytometry also showed similar findings. Conclusions: Topical cyclosporin A effectively reduces stromal haze and inflammation in experimental HSK, and cyclosporin A eyedrops with a > 0.1% concentration can be used for the treatment of HSK.