Erythropoietin protects the retinal pigment epithelial barrier against non-lethal H₂O₂-induced hyperpermeability

Abstract

Erythropoietin (EPO) is not limited to hematopoiesis; it may act as a protective cytokine. In this study, the retinal pigment epithelial (RPE) cell viability, cell monolayer integrity, RPE barrier permeability, distribution of the junction proteins ZO-1, occludin and the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were monitored to evaluate the effect of EPO on non-lethal H₂O₂-induced RPE barrier hyperpermeability. Results showed that, EPO increased the viability of H₂O₂-treated RPE cells, the disruption of junction proteins and the higher permeability caused by H₂O₂ was partially prevented by EPO pre-treatment. EPO treatment also induced lower MDA levels and higher SOD activity in H2O2 treated RPE cells. So, it is concluded that, non-lethal concentrations of H₂O₂ could damage RPE barrier and destroy its integrity. EPO showed the protective effects on H₂O₂-induced hyperpermeability by stabilizing the distribution of junction proteins and reducing oxidative stress. These results indicated that, EPO may have the therapeutic potential use in the treatment of eye diseases involving RPE barrier hyperpermeability induced by oxidative stress.

Key words: Erythropoietin, retinal pigment epithelial, oxidative stress, tight junction.