Autophagy protects retinal pigment epithelial cells from hydroquinone‐induced toxicity

Abstract

AbstractPurpose: Age‐related macular degeneration (AMD) is a complex disease and the most common cause of blindness among the elderly in the Western world. Dysfunctional cellular clearance and increased oxidative stress are known to play a role in retinal pigment epithelial (RPE) cell death and dysfunction, which secondarily leads to photoreceptor degeneration and a loss of central vision. Smoking, which increases oxidative stress on a cellular level is a known risk factor for AMD. Here we assess the role of autophagy in the survival of ARPE‐19 cells exposed to the cigarette smoke component hydroquinone and in the secretion of the vascular endothelial growth factor (VEGF).Methods: We exposed ARPE‐19 cells to 100 μM hydroquinone following either 1 h or 24 h of serum‐starvation, which induced autophagic clearance. At the same time, autophagy was inhibited either at the early or the late stage using 3‐Methyladenine or bafilomycin A1, respectively. Cytotoxicity was assessed using the lactate dehydrogenase (LDH) or the MTT assay. VEGF secretion was measured from the medium using ELISA.Results: Hydroquinone exposure reduced cell viability to 50% of control when hydroquinone was added following a 1 h serum starvation. Inversely, if cells were starved for 24 h prior to hydroquinone exposure, no toxicity was observed. Inhibition of autophagy at the early but not the late stage significantly reduced the survival of cells starved for 24 h prior to hydroquinone exposure. At the same time, autophagy inhibition significantly reduced VEGF secretion to the medium.Conclusions: Autophagy activation effectively prevented oxidative stress‐induced cytotoxicity in RPE cells, highlighting the importance of functional autophagy in RPE cells and in the prevention of AMD.