Antioxidant and osmoprotecting activity of taurine in dry eye models

Purpose: To assess the protective effects of ophthalmic formulations based on taurine (TAU) and sodium hyaluronate (SH) in ocular surface.Methods: Rabbit corneal epithelial cells (SIRCs) were subjected to oxidative stress (1 mM H2O2) and treated with the following formulations: 0.2% SH, 0.4% SH, 0.4% SH + 0.5% TAU. Reactive oxygen species (ROS) were evaluated by commercial kit. Dry eye was induced by atropine sulfate and topical treatment were carried out with the following formulations: 0.2% SH, 0.4% SH, 0.4% SH + 0.5% TAU. Schirmer’s test, tear breakup time (TBUT) and tear osmolarity were evaluated. Furthermore, tear MMP-9 expression was assessed by Western blot. Results: Taurine significantly (p<0.05) decreased ROS production in SIRC after oxidative stress. Topical administration of atropine in the rabbit eye significantly (p<0.05) reduced tear volume and TBUT. Tear osmolarity was also significantly (p<0.05) modified by atropine treatment. All the altered parameters were significantly (p<0.05) reversed by 0.5% TAU + 0.4% SH treatment; further, this formulation was more effective compared to SH alone. Moreover, tear levels of MMP-9 were significantly (p<0.05) lower in the group treated with 0.5% TAU + 0.4% SH. Conclusions: Altogether these data suggest that taurine has a relevant antioxidant effect in corneal epithelial cells and prevents the ocular surface damage elicited by atropine. Therefore, our findings suggest that taurine in combination with sodium hyaluronate may be useful in clinical practice to manage ocular surface diseases.