Quercetin alleviates 4-hydroxynonenal-induced cytotoxicity and inflammation in ARPE-19 cells.

Retinal pigment epithelium (RPE) plays the principal role in age-related macular degeneration (AMD), a progressive eye disease with no cure and limited therapeutical options. In the pathogenesis of AMD, degeneration of RPE cells by multiple factors including increased oxidative stress and chronic inflammation precedes the irreversible loss of photoreceptors and central vision. Here, we report that the plant-derived polyphenol, quercetin, increases viability and decreases inflammation in stressed human ARPE-19 cells after exposure to the lipid peroxidation end product 4-hydroxynonenal (HNE). Several previous studies have been conducted using the direct oxidant H2O2 but we preferred HNE since natural characteristics predispose RPE cells to the type of oxidative damage evoked by lipid peroxidation. Quercetin improved cell membrane integrity and mitochondrial function as assessed in LDH and MTT tests. Decreased production of proinflammatory mediators IL-6, IL-8, and MCP-1 were indicated at the RNA level by qPCR and at the protein level by the ELISA technique. In addition, we probed the signaling behind the effects and observed that p38 and ERK MAPK pathways, and CREB signaling are regulated by quercetin in ARPE-19 cells. In conclusion, our present data suggests that HNE is highly toxic to serum-starved ARPE-19 cells but quercetin is able to reverse these adverse effects even when administered after an oxidative insult.