Exosomes derived from RPE cells under oxidative stress mediate inflammation and apoptosis of normal RPE cells through Apaf1/caspase‐9 axis

Abstract

This study aims to explore the effects of exosomes, secreted by retinal pigment epithelial (RPE) cells under oxidative stress (OS), on apoptosis and inflammation of normal RPE cells. Exosomes secreted by normal RPE cells (named as exo) and rotenone (2.5 µmol/L) stimulated RPE cells (named as rot-exo) were isolated and extracted by multi-step differential centrifugation for morphology observation under a transmission electron microscopy. pcDNA3.1a, pcDNA3.1a-Apaf1, and p3xFlag-CMV-caspase-9 plasmids were constructed and transfected into ARPE-19 cells. Exosomes secreted by ARPE-19 cells were injected into the vitreous body of rats to verify the effect of Apaf1 and caspase-9 on cell apoptosis and inflammation. Co-immunoprecipitation was applied to clarify the interaction of Apaf1 with caspase-9. Exosomes secreted by rotenone stimulated ARPE-19 cells could induce cell apoptosis, oxidative injury, and inflammation in ARPE-19 cells. Exosomes secreted under OS can damage retinal functions of rats and have upregulated expression of Apaf1. Overexpression of Apaf1 in exosomes secreted under OS can cause the inhibition of cell proliferation, the increase of cell apoptosis and elicitation of inflammatory response in ARPE-19 cells. Exosomes derived from ARPE-19 cells under OS regulate Apaf1 expression to increase cell apoptosis and to induce oxidative injury and inflammatory response through a caspase-9 apoptotic pathway. K E Y W O R D S caspase-9, cell apoptosis, exosomes, reactive oxygen species, retinal pigment epithelium cells 1 | INTRODUCTION Retinal pigment epithelium (RPE) is a monolayer of cells that undertake the function and viability of photoreceptor cells. 1 RPE could provide nutrients to secure visual function and could impact the formation of the outer blood-retinal barrier which avoids nonspecific diffusion and material transportation from the choroid. 2 The degradation of RPE cells is part of the pathology involved in age-related macular degeneration (AMD) whose etiology remains to be largely determined. 3 RPE is vulnerable to oxidative stress (OS), particularly to reactive oxygen species (ROS). 4 OS is Yifeng Ke and Xiaoe Fan contributed equally to this work.

Extracellular Vesicles in HTLV-1 Communication: The Story of an Invisible Messenger

“…These EVs promoted angiogenesis in endothelial cells [ 208 ]. Another study showed that EVs obtained from RPE cells treated with an oxidative stressor (i.e., Rotenone) caused a reduction in cell proliferation and survival of normal RPE in a dose-dependent manner [ 209 ]. These EVs contained high level of apoptotic protease activating factor 1 (Apaf1) that most likely enhanced the induction of apoptosis and inflammatory response in the normal RPE cells [ 209 ].…”

“…Another study showed that EVs obtained from RPE cells treated with an oxidative stressor (i.e., Rotenone) caused a reduction in cell proliferation and survival of normal RPE in a dose-dependent manner [ 209 ]. These EVs contained high level of apoptotic protease activating factor 1 (Apaf1) that most likely enhanced the induction of apoptosis and inflammatory response in the normal RPE cells [ 209 ]. Lastly, Tax has been found to stimulate the production of reactive oxygen species (ROS) in primary human cells resulting in cellular DNA damage and cellular senescence [ 210 ].…”

A Comprehensive Review on Factors Influences Biogenesis, Functions, Therapeutic and Clinical Implications of Exosomes

“…Exosomes derived from ARPE-19 cells under OS regulate Apaf1 expression to increase apoptosis and to induce oxidative injury and inflammatory response through a caspase-9 apoptotic pathway. 172 Collectively, these findings highlight the critical role of exosomes in inflammation and suggest the possibility of utilizing exosomes as an inducer to attenuate inflammation and restore impaired immune responses in various diseases including cancer.…”

Emerging Role of Exosomes in Retinal Diseases

“…On the other hand, oxidative stress can not only promote the release of exosomes from RPEs, but also make receptor cells engulf exosomes more quickly in the progression of AMD disease ( Nicholson et al, 2020a ; Yang et al, 2020 ). Exosomes under oxidative stress can also increase apoptosis of ARPE-19 cells through overexpression of Apaf1 and induce oxidative damage and inflammation through caspase-9 apoptosis pathway ( Ke et al, 2020 ). In another study exosome from J-cybrids reduced transepithelial resistance (TER) in receptor ARPE-19 cells, and this is associated with high risk of AMD ( Nicholson et al, 2020b ).…”