Grape Seed Extracts Inhibit the Overexpression of Inflammatory Cytokines in Mouse Retinas and ARPE-19 Cells: Potentially Useful Dietary Supplement for Age-Related Eye Dysfunction.

Aging can cause retinal degeneration, which leads to visual impairment among the elderly population. Age-dependent increases in amyloid beta (A) inducesinflammatory cytokine overexpression in the retinal pigment epithelium (RPE), which promotes the progression of age-related retinal degeneration. However, whether dietary antioxidants are useful for the treatment of RPE degeneration remains to be clarified. This study exposited the protective activities and underlying mechanisms of grape seed extracts (GSEs) against A-induced proinflammatory events in mouse retinas and ARPE-19 cells. The experimental data demonstrated that GSEs attenuated the increases in messenger RNA (mRNA) levels of interleukin 12 (IL-12), interleukin 6 (IL-6), interleukin 1 (IL-1), and interleukin 18 (IL-18) in the retinal tissues of A-treated mice. The experimental results in mice were confirmed by findings in ARPE-19 cells with or without treatment with GSEs. GSEs affected the protein expression levels of endoplasmic reticulum stress markers in ARPE-19 cells exposed to A. Knockdown of Bip blocked the inhibitory activities of GSEs on mRNA levels of IL-6, IL-1, IL-18, and IL-8. We conclude that GSEs may suppress proinflammatory cytokines partly by increasing the expression of Bip.