Changes in the Gut Microbiome Contribute to Changes in Tissue Gene Expression in Rats Fed Prebiotic Dietary Fibers (P15-022-19)

Abstract

ObjectivesWe investigated the intersection between the gut microbiome and gene expression of colon and liver tissues in rats, using prebiotic dietary fibers to modulate the gut microbiome and elicit health benefits to the host. MethodsMale Wistar rats were fed normal fat (NF) or high fat (HF, 51% fat by kcal) diets containing various fibers (6% fiber + 3% cellulose, by weight); including cellulose (NFC and HFC, non-fermentable), polylactose (HFPL, a novel prebiotic), and polydextrose (HFPD, an established prebiotic). After 10 weeks, tissues were harvested. Transcriptome analysis was performed by RNA sequencing of colon and liver tissues, and cecal contents were utilized for 16S microbiome sequencing. Analyses were conducted in R using DESeq2, DADA2, and phyloseq. ResultsAnalysis of the gut microbiome revealed an increased abundance of probiotic genera, Bifidobacterium and Lactobacillus, in HFPL fed animals when compared to all other groups. These species are galactose fermenters which synthesize short chain fatty acids (SCFAs). This increased taxonomical abundance correlated with an increased FFar3 (SCFA receptor) expression in the colon. This suggests increased FFar3 signaling, leading to increased energy expenditure and GLP-1 and PYY secretion. Additionally, HFPL and HFPD groups had a decreased Firmicutes: Bacteroidetes ratio, which is associated with reduced adiposity due to the Bacteroidetes phylum being poor carbohydrate metabolizers, resulting in reduced energy uptake, yet increased SCFA synthesis.Bacteriodetes are also able to survive in SCFA and bile acid rich environments and are involved in the recycling of bile acids which negatively regulates cholesterol synthesis. This corresponds to reduced liver cholesterol and cholesterol synthesis pathway expression in the HFPL group. Further, liver gene expression revealed reduced lipid synthesis and increased lipid oxidation pathway gene expression in the HFPL group, corresponding to the reduction in fatty liver found in this group. ConclusionsPrebiotic dietary fibers elicit changes in the gut microbiome and gene expression in liver and colon. Changes in gene expression correlated with the abundance of beneficial gut bacteria, providing a connection between the gut microbiome and health benefits to the host. Funding SourcesMidwest Dairy Association. Supporting Tables, Images and/or Graphs▪▪▪