Abstract
Purpose :
The outer retina is subjected to a highly oxidative and cell-damaging milieu. Under healthy conditions, however, oxidative damage is buffered by a large array of defensive mechanisms. By contrast, in age-related macular degeneration (AMD), the appearance of oxidative changes suggests that environmental and genetical alterations in retinal protection mechanisms would allow the destruction of the retinal pigment epithelium (RPE) and photoreceptors. Since enhancement of cellular antioxidant mechanisms could be beneficial for AMD, we have tested caffeic (CAF) and chlorogenic (CHL) acids on H2O2-induced damage of RPE-derived ARPE-19 cells.
Methods :
ARPE-19 cell damage was induced by H2O2 (150 µM) for 90 minutes. Polyphenols were applied before damage (70 µM CAF or 100 µM CHL for 2 hours). Cells were collected at different times to test reactive oxygen species (ROS) using a fluorogenic probe and nuclear damage as reflected by the repair histone p-H2AX and the senescence-associated markers p16 and p21. β-galactosidase (β-gal) activity was also assessed. To evaluate defensive mechanisms, we measured p-CREB and BCL2 by Western blot, and NRF2 and SOD2 expression by qPCR.
Results :
Both polyphenols showed similar effects. They decreased ROS fluorescence and all nuclear damage markers. The repair histone p-H2AX almost disappeared, and senescence markers were significantly decreased. After 12 days, β-gal+ cells were reduced to 50%. By contrast, p-CREB and BCL2 expressions were significantly increased (p < 0.05), and the expression of ROS detoxifying genes NRF2 and SOD2 was enhanced (p < 0.05).
Conclusions :
Our results show that CAF and CHL protected RPE cells from oxidative damage. These polyphenols displayed a direct antioxidant action coupled to a signaling role in antioxidant pathways, as revealed by an immediate drop of ROS levels and the increase of p-CREB, BCL2, NRF2 and SOD2, respectively. Reduction of oxidative stress damage in our model suggests that a role of these polyphenols in the prevention of retinal damage is plausible. Furthermore, prevention could be supported by the intake of foods and beverages containing these molecules, such as yerba mate and coffee.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.