Exendin-4 Protects Human Retinal Pigment Epithelial Cells from H₂O₂-Induced Oxidative Damage via Activation of NRF2 Signaling

Abstract

Aims: Oxidative damage plays a vital role in the pathogenesis of age-related macular degeneration (AMD). Exendin-4 (EX4), a glucagon-like peptide-1 receptor agonist, possesses several pharmacological functions, such as anti-inflammatory and antioxidative properties. However, the effects and mechanism of EX4 on oxidative stress in retinal pigment epithelial (RPE) cells induced by hydrogen peroxide (H 2 O 2) remain unclear. The present study aimed to investigate the protective mechanism of EX4 on human RPE cells subjected to oxidative stress. Methods: Human RPE ARPE-19 cells were treated with H 2 O 2 to induce oxidative damage. Cell viability was determined by Cell Counting Kit-8 and lactate dehydrogenase assay. Levels of intracellular reactive oxygen species (ROS), malonyldialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH) were measured using commercial kits. The expression of nuclear factor erythroid 2-related factor-2 (NRF2), heme oxygenase-1 (HO-1), and NAD(P)H:quinone oxidoreductase-1 (NQO-1) was measured using reverse transcription quantitative polymerase chain reaction assay and western blot, respectively. Results: H 2 O 2 significantly induced oxidative stress to reduce viability of RPE cells and increased intracellular ROS generation. EX4 significantly ameliorated H 2 O 2-induced oxidative damage by reducing intracellular ROS generation, decreasing MDA concentration, and increasing antioxidant enzymes activities (SOD and GSH). In addition, EX4 markedly increased expression of NRF2, HO-1, and NQO-1 and significantly improved protein expression of NRF2 and HO-1 in H 2 O 2-treated ARPE-19 cells, caused by increased nuclear NRF2 protein expression. NRF2 knockdown by targeted siRNA alleviated EX4-mediated HO-1 expression and significantly nullified EX4-mediated RPE cell protection against H 2 O 2. Conclusions: EX4 attenuated oxidative damage induced by H 2 O 2 in ARPE-19 cells through the activation of the NRF2 signaling pathway. The findings suggested that EX4 may be a potential therapeutic agent for the treatment of AMD.

Spermidine Attenuates Oxidative Stress-Induced Apoptosis via Blocking Ca2+ Overload in Retinal Pigment Epithelial Cells Independently of ROS

“…Dysfunction and cell death in RPE cells are hallmarks of AMD; mechanistically, oxidative stress and reactive oxygen intermediates are believed to contribute to RPE cell death in AMD [26]. To identify the pathological mechanism of RPE dysfunction in AMD, numerous studies have evaluated RPE cell death in response to oxidative stress using pro-oxidants such as H 2 O 2 and tert-butyl hydroperoxide (tBH) [27][28][29][30]. In the present study, we found that H 2 O 2 led to cytotoxicity above 200 µM in ARPE-19 cells and accompanied apoptotic morphological changes.…”

Alisol A 24-acetate protects oxygen–glucose deprivation-induced brain microvascular endothelial cells against apoptosis through miR-92a-3p inhibition by targeting the B-cell lymphoma-2 gene

“…Production of ROS and MDA was widely used to reflect the level of oxidative stress; conversely, SOD, which acts as an antioxidant, is essential to decrease the overproduction of ROS and MDA to prevent vascular injury and cell death (Cui et al. 2020 ). OGD induces inflammatory responses and oxidative stress by increasing the levels of TNF-a, IL-1β, IL-6, ROS and MDA and decreasing SOD activity (Zhao et al.…”

Eye-Light on Age-Related Macular Degeneration: Targeting Nrf2-Pathway as a Novel Therapeutic Strategy for Retinal Pigment Epithelium

“…In the context of Keap1/Nrf2/ARE signaling pathway as a druggable target for AMD and other pathologies, various natural and synthetic Nrf2 activators have been recently tested in both in vitro and in vivo studies to evaluate their protective effects against different pro-oxidant stimuli (Pietrucha-Dutczak et al, 2018;Cui et al, 2019;Shao et al, 2019;Zhou et al, 2019;Fresta et al, 2020). In this panorama, our NIHs look as noteworthy pharmacological molecules, displaying a good profile of tolerability ( Figure 3) and uncommon cytoprotective effects in RPE cells under three different types of AMD-related oxidative stress.…”