# Caffeine Alleviates Oxidative Damage of Retinal Pigment Epithelium Cells

## TL;DR

Caffeine protects retinal cells from oxidative damage and improves retinal health in mice.

## Contribution

This study demonstrates that caffeine reduces oxidative stress and DNA damage in retinal pigment epithelium cells.

## Key findings

- Caffeine increases cell viability and reduces apoptosis in H2O2-treated ARPE-19 cells.
- Caffeine modulates BAX, BCL2, and p21 proteins to exert cytoprotective effects.
- Caffeine alleviates oxidative damage and improves retinal structure in a mouse model of retinal degeneration.

## Abstract

The purpose of this study was to explore the protective effect of caffeine on oxidative damage of RPE cells and NaIO3‐induced retinal degeneration.

H2O2 was used to induce the oxidative damage in ARPE‐19 cells. Cell viability was measured by the CCK‐8 assay. The morphology of ARPE‐19 cells was observed by optical microscope. The apoptosis of ARPE‐19 cells was analyzed by Annexin V/PI staining, and DNA fragmentation was detected using the TUNEL assay. The protein levels of apoptosis markers BAX and BCL2 as well as senescence marker p21 were detected by Western blot. DNA damage was indicated by immunofluorescence staining of γ‐H2AX and observed by fluorescence microscopy. Transcriptome profiling of ARPE‐19 cells was performed by RNA‐seq. In vivo model of retinal oxidative damage was constructed by injecting NaIO3 into the tail vein of C57BL/6 mice. H&E staining was performed after removing the eyeballs.

The CCK‐8 assay showed that caffeine could significantly increase the cell viability inhibited by 200 μM H2O2. Caffeine significantly reduced H2O2‐induced DNA fragmentation and apoptosis in ARPE‐19 cells, as demonstrated by the TUNEL assay and Annexin V/PI staining. The results of Western blot showed that caffeine modulated key proteins associated with apoptosis by decreasing BAX and p21 levels while increasing BCL2 expression in H2O2‐treated ARPE‐19 cells, thereby suggesting its cytoprotective effects. In terms of mechanism, caffeine reduced the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) produced by H2O2. Caffeine treatment attenuated the accumulation of γ‐H2AX, a marker of DNA damage, in ARPE‐19 cells. Importantly, transcriptome profiling revealed that caffeine might affect complement cascade and lipid metabolism in H2O2‐treated ARPE‐19 cells. Finally, in vivo experiment suggested that chronic administration of caffeine could alleviate oxidative damage of the RPE layer and improve the structure of the entire retina in mice with NaIO3‐induced retinal degeneration.

Caffeine can reduce oxidative damage of RPE cells and improve NaIO3‐induced retinal degeneration.