Oxidative stress, autophagy, and exosome liberation in retinal pigment epithelium cells

Abstract

Purpose : The retinal pigment epithelium (RPE), is very sensitive to suffer oxidative stress insult, specifically due to reactive oxygen species (ROS). Overproduction of ROS activates cellular self-defend mechanisms, but when such production is excessively high, cell death eventually occurs. There are a number of well-known products that produce oxidative stress in the RPE, such is the case of H₂O₂ and rotenone. Lately it has been observed the malignant influence of ethanol (EtOH) in several tissues, including the RPE. Recently, it has been observed that excessive ROS formation in RPE cells can deregulate other physiological mechanisms, such as autophagy and the liberation of extracellular particles known as exosomes. Correlations between autophagy and exosome release has been proposed already. Apparently both mechanisms share common pathways to a certain degree. In fact, during MVB biogenesis, delivery of selected cytosolic proteins into the late endosome seems to occur through a microautophagy-like process. We believe that, under oxidative conditions, both processes collaborate as a defense and communication strategy. We therefore hypothesize that exosomes released by EtOH-stressed RPE cells will be able to control autophagy in neighboring cells. We also believe that autophagy and exosome release will join forces to establish homeostasis in the damaged cells.

Methods : Exosomes derived from ARPE-19 cells (control and treatment) were isolated and quantified proteins of autophagy and apoptosis pathway by flow cytometry and western blot

Results : High concentrations of ethanol induce an increase in number of exosomes and alters the content of this microvesicles, particularly proteins associated with apoptotic and autophagic pathway. In addition, the inhibition or silenced of autphagy affect the exoxomes cargo.

Conclusions : In agreement with other researchers, there is a close relationship between the biogenesis of exosomes and autophagy. In addition, exosome and autophagy pathways are altered upon exposure to ethanol

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.