Black Raspberry Supplementation Alters the Gut Microbiome and Improves Alpha Diversity in a Mouse Model of Inflammation-Associated Colorectal Cancer

Abstract

ObjectivesAnti-inflammatory bioactives in black raspberries (BRB) have been shown to have protective effects on the colon epithelium and may influence gut microbiome. The goal of this study was to determine the effects of dietary intervention with BRB on the dynamic composition of the gut microbiome composition in mice. MethodsUsing a 2 × 2 factorial design, C57BL/6J male mice were fed the standard AIN93G diet or the total Western diet (TWD) for 16 weeks with or without 10% (w/w) whole, freeze-dried BRB powder. The azoxymethane + dextran sodium sulfate model of inflammation-associated colorectal cancer was employed to assess the dynamic response of the gut microbiome to basal diet and BRB treatment prior to, during, and after active colitis and at the study end. Microbiome composition was determined using 16s rRNA sequencing followed by diversity analyses (alpha and beta) and identification of discriminating taxa by with linear discriminant analyses by effect size (lefse). ResultsAlpha diversity was markedly reduced during colitis for mice consuming either AIN93G or TWD, with some improvement noted by the recovery phase. Of note, consumption of BRB for two weeks significantly increased alpha diversity measures, and BRB improved alpha diversity in mice fed the AIN93G diet during colitis. Alternatively, BRB appeared less effective in mice fed TWD. Beta diversity was also significantly affected with notable clustering of microbiomes by BRB treatment during and after colitis. Consumption of BRB affected the relative abundance of several key taxa over the course of colitis and recovery from gut injury, including Erysipelotrichaceae, Bifidobacteriaceae, Streptococcaceae, Rikenellaceae, Ruminococcaceae and Akkermansiaceae, among others. ConclusionsDietary supplementation with BRB shifted the composition of the gut microbiome during colitis and recovery from gut injury, though the effects were inconsistent with respect to the basal diet consumed. Funding SourcesUSDA NIFA AFRI grant no. 2018-67017-27,516 and 2014-67017-21755.