High-Fat Diet Enriched with Bilberry Modifies Colonic Mucus Dynamics and Restores Marked Alterations of Gut Microbiome in Rats

Abstract

Scope: Emerging evidence suggests that high-fat diet (HFD) is associated with gut microbiome dysbiosis and related disorders. Bilberry is a prebiotic food component with known health benefits. Herein, the dynamics of the colonic mucus layer and microbiome during HFD and bilberry supplementation are addressed.

Methods and results: The effects on colonic mucus thickness in vivo and gut microbiota composition (Illumina sequencing, quantitative real-time PCR) are investigated in young rats fed a low-fat diet or HFD with or without bilberries for 8 weeks (n = 8). HFD induced significant local colonic effects, despite no observed weight gain or systemic inflammation, as HFD causes epithelial upregulation of inducible nitric oxide synthase, which is counteracted by bilberry. The firmly adherent mucus layer becomes thicker and the mRNA levels of Muc2 and Tff3 are increased by HFD with or without bilberry. In parallel, HFD reduced the colonic abundance of mucolytic bacterial species Akkermansia muciniphila and Bacteroides spp. Finally, bilberry prevents HFD-induced microbiota dysbiosis, including expansion of pathobionts, for example, Enterobacteriaceae.

Conclusion: HFD expand firmly adherent mucus thickness and reduce mucus-foraging bacteria populations in the colon prior to obesity. Enriching HFD with bilberry protects against intestinal inflammation and marked microbiota encroachment.

Keywords: Akkermansia muciniphila; bilberries; gut microbiome; high-fat diet; mucus.