Abstract
Purpose :
Degeneration of the retinal pigment epithelial (RPE) underscores the pathology in geographic atrophy (GA), a late stage dry age-related macular degeneration (AMD). Oxidative stress and aging are known to contribute to GA pathogenesis. However, how RPE cells die in GA is still controversial. 4-Hydroxynonenal (4-HNE) is an oxidative stress marker produced by lipid peroxidation, which is accumulated in aging cells and could be related to age-related diseases. The goal of the study is to determine the mechanism of 4-HNE-induced RPE cell death.
Methods :
ARPE-19 cells were treated with 4-HNE at different concentrations to induce cell death. Inhibitors of apoptosis, necroptosis, pyroptosis and ferroptosis pathways, were used to test for their effect on cell viability. Cell morphology and molecular markers (including PYCARD and RIPK3) were examined under a microscope. ATP and ROS levels were measured using standard methods.
Results :
We found that 4-HNE (5-10 ug/ml) induces significant RPE cell death, consistent with significantly decreased cellular ATP but increased ROS levels. Necrosis inhibitor Necrostatin-7 and ferroptosis inhibitors liproxstatin-1 and DFO, but not apoptosis inhibitors, prevented 4-HNE-induced RPE cell death. On the molecular level, both inflammasome and necrosome are activated in RPE cells treated with 4-HNE, as shown by PYCARD and RIPK3 visualization.
Conclusions :
Ferroptosis and/or necroptosis, but not apoptosis, underlie RPE death induced by 4-HNE. Crosstalk between different cell death pathways may occur when RPE cells are under oxidative stress. The inhibitors from our study may have therapeutic implications for GA.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.