(P14-005-24) Anti-inflammatory Effect of Brewer's Spent Grain In Vitro

Objectives: Brewer's spent grain (BSG) is a byproduct produced during the beer brewing process. It is rich in fibers, proteins, and bioactive compounds that have various health benefits such as reducing cholesterol and anti-diabetes effects. Inflammation is the immune response and healing process to remove harmful stimuli, and it is highly associated with the development of chronic diseases like obesity and diabetes. Thus, reducing inflammation is essential for improving human health. Our previous study found that BSG reduced obesity by reducing lipid absorption in the intestine, which suggests a possible beneficial effect of BSG in obesity-induced inflammation in the intestine. Therefore, the purpose of this study is to examine the anti-inflammatory effect of BSG extract using Caco-2 cells in vitro.

Methods: The BSG extract was obtained through a liquid-liquid extraction method using 60% aqueous ethanol (v/v). Caco-2 cells were cultured, differentiated, and then treated with 5, 15, and 30 µg of BSG extract for 12 hours. The cells were successively treated with BSG extract and inflamed for the next 12 hours with lipopolysaccharide (LPS). Genes that are involved in the regulation of inflammation and tight junction were measured using a real-time PCR. The data was analyzed using one-way ANOVA with Tukey's post-hoc test of significance at P < 0.05.

Results: LPS-stimulated Caco-2 cells showed significant increases in interleukin 6, interleukin-12, and monocyte chemoattractant protein-1. BSG extract treatment at 5, 15, and 30 µg suppressed interleukin 6, interleukin-12, and monocyte chemoattractant protein-1 gene expression levels by 29%, 43%, and 57%, 53%, 53%, and 74%, and 16%, 45%, and 77%, respectively. LPS-induced cyclooxygenase-2, tumor necrosis factor α, interleukin-1β genes were reduced by 46%, 26%, and 58% in cells treated with 5 µg BSG, respectively, but there was no additional reduction by higher concentrations of BSG extract. LPS decreased the expression of genes to regulate tight junction function, zonula occuldens-1, claudin 1, claudin 4, and occludin. These genes were upregulated in the Caco-2 cells treated with BSG extract.

Conclusions: Taken together, BSG extract showed the potential to reduce intestinal inflammation. BSG may be a promising dietary resource for enhancing intestinal health.

Funding Sources: This study was supported by USDA.