Raspberry Protects Against High-Fat, High-Sucrose Diet-Induced Vascular Oxidative Stress via NRF2

Abstract

ObjectivesElevated free fatty acids in obesity and high-fat diets can negatively impact artery function, increasing the risk of cardiovascular diseases. Raspberries (RB) are a concentrated source of polyphenols which can mediate cellular pathways in a protective manner. Thus, the objective of this study was to examine whether RB consumption could mitigate the detrimental effects of a high-fat high-sucrose (HFHS) diet in the aorta of mice in vivo and human aortic endothelial cells (HAECs) in vitro. MethodsEight-week-old male C57BL/6 mice were fed an AIN-93M control diet with or without 10% w/w freeze-dried RB supplementation for 4 weeks. At week 4, animals were randomized into three groups: control, HFHS, or RB + HFHS. After 24 weeks of dietary treatment, mice were sacrificed and aortas dissected for immunohistochemistry analysis. HAECs were cultured in endothelial cell growth medium and treated with 200 μg/ml of RB extract in starvation medium. After 2 h, cells were treated with 100 μM of palmitic acid (PA) for 6 h. Cells were then collected for protein expression analysis via western blot. Data were normalized to control. Statistical analysis was conducted with ANOVA followed by Dunnett’s multiple comparisons test. ResultsIn aorta, nitrotyrosine was increased in the HFHS group compared with control and RB + HFHS group. Additionally, inducible nitric oxide synthase was increased in both HFHS and RB + HFHS compared to control, but expression was not different between HFHS groups. In HAECs, PA alone had no effect on phosphorylation of endothelial nitric oxide synthase (p-eNOSSer1177) compared to control. However, p-eNOSSer1177 expression was significantly increased in RB + PA -treated cells compared to both control and PA alone. Nuclear factor erythroid 2–related factor 2 (NRF2) and heme oxygenase (HO)-1 expression was also significantly increased with RB + PA treatment compared to control and PA alone. ConclusionsRaspberry consumption may reduce vascular oxidative stress induced by a HFHS diet via reduced NO oxidation despite increased iNOS in vivo. Further in vivo investigation is needed to confirm whether these effects are mediated by increased NRF2 activity. Funding SourcesLewis College Foundation and Agriculture and Food Research Initiative (grant no. 2019–67,017-29,257/project accession no. 1,018,642) from the USDA National Institute of Food and Agriculture.