Red raspberry supplemented serum reduces inflammatory stress signals in HAPI rat microglial cells, in vitro

Authors: Fisher, Derek; Piccolo, Francesca; XIAO, DI - Illinois Institute Of Technology; BURTON-FREEMAN, B. - Illinois Institute Of Technology; Shukitt-Hale, Barbara

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/3/2023
Publication Date: 7/22/2023
Citation: Fisher, D.R., Piccolo, F.X., Xiao, D., Burton-Freeman, B.M., Shukitt Hale, B. 2023. Red raspberry supplemented serum reduces inflammatory stress signals in HAPI rat microglial cells, in vitro. [Abstract]. 7(Suppl 1):101220. https://doi.org/10.1016/j.cdnut.2023.101220.
DOI: https://doi.org/10.1016/j.cdnut.2023.101220

Interpretive Summary:

Technical Abstract: Objectives: Age-related neurodegeneration and behavioral declines are thought to result from increased susceptibility to oxidative stress and inflammation in the brain. Raspberries contain bioactive phenolic compounds that exhibit potent antioxidant and anti-inflammatory activities. To address challenges of bioaccessibility when testing a food in an in vitro model, we tested the validity of pre-treatment of stressed cells with serum from people fed raspberries as a model system for assessing raspberries’ anti-inflammatory effects. Methods: The effects of acute raspberry supplementation in 25 older (55-70 years old), overweight/obese (BMI 27-35) adults were examined in a double-blind, placebo-controlled, crossover study. Participants consumed a red raspberry (25g freeze-dried powder) or placebo drink with a high-fat breakfast challenge. Blood was collected at baseline (0 hour), then again at 2 and 6 hours post-consumption. HAPI rat microglial cells were treated with 10% serum (for each individual, at each timepoint, in duplicate) for 8 hours prior to stressor application with LPS at 200 ng/mL overnight, and expression of nitric oxide, COX-2, and iNOS were measured by western blot and ELISA as inflammatory indices. Results: Microglia treated with serum from participants who consumed raspberry demonstrated reduced LPS-induced neuroinflammation on all measures, compared to cells treated with placebo, at both 2 and 6 hours (p<0.05). Only iNOS was lower at 2 hours compared to 6 hours, suggesting a temporal effect. These changes also align with the biphasic increase in plasma concentrations of phenolic acid metabolites seen in human studies, with some peaking at 1–2 h and others at 6 hours. Conclusions: These results suggest that parent compounds or metabolites from the berry fruit, which are present in the circulating blood, may be mediating anti-inflammatory effects, but further chronic studies are needed to determine long-term benefits to health in humans.