Effect of Topically Applied Azithromycin on Corneal Epithelial and Endothelial Apoptosis in a Rat Model of Corneal Alkali Burn

Purpose: To investigate the antiapoptotic effect of topically administered azithromycin (AZM) on corneal epithelial and endothelial cells in a rat model of corneal alkali burn. Methods: Twenty-four Wistar albino rats were divided into 4 equal groups as pseudovehicle (group 1), control (group 2), alkali burned (group 3), and treatment (group 4) groups. Alkali injury was induced only in the right corneas of rats belonging to groups 3 and 4 using 1N NaOH. The rats in group 3 and the rats in group 4 were respectively treated either with an artificial tear gel or with 1.5% AZM eye drops for 5 days. At the fifth day of the experiment, the apoptosis in the corneal epithelium and endothelium of all rats was assessed using a terminal dUTP nick-end labeling (TUNEL) assay. In addition, tumor necrosis factor-alpha (TNF-alpha) density in the corneal epithelium was measured in all rats. Results: The mean numbers of TUNEL+ cells in the corneal epithelium and endothelium of rats in group 3 were 117.1 +/- 23.8 and 34.6.+/- 11.3, respectively, whereas in group 4, they were 75.8 +/- 15.7 and 14.7 +/- 3.5, respectively. Also the mean TNF-alpha densities in the corneal epithelium in group 3 and group 4 were 2.65 +/- 1.3 and 1.65 +/- 1.1, respectively. There was a significant decrease in the mean number of TUNEL+ cells in the corneal epithelium and endothelium and in the mean TNF-alpha density in the corneal epithelium of rats in group 4, when compared with group 3. Conclusions: Topically applied AZM can decrease TNF-alpha-induced apoptosis in corneal alkali burn.