Structural and Functional Alterations in the Colonic Microbiome in a Rat Model of Stress Induced Irritable Bowel Syndrome

Authors

• NH Fourie
• D Wang
• SK Abey
• AL Creekmore
• S Hong
• C Martin
• JW Wiley
• WA Henderson

Abstract

Stress is implicated in the pathogenesis of irritable bowel syndrome (IBS) and exacerbates IBS symptoms (e.g. dysmotility, visceral hypersensitivity and colonic permeability). We investigated the effects of chronic stress, which causes persistent IBS-like symptoms in the rat, on the structure and function of the colonic microbiome. V4 16S sequencing was used to characterize the bacterial diversity and abundance of the colonic mucosa-adherent microbiome of control animals (C, n = 13) and animals repeatedly exposed to a water avoidance stressor (WA, n = 13). In silico analysis of the functional domains of microbial communities was done by inferring metagenomic profiles from 16S data. WA animals exhibited higher alpha-diversity and moderate divergence in microbial community structure (beta-diversity) compared to controls. Several microbial clades were consistently modified in the WA animals. The WA microbiome exhibited higher alpha-diversity and moderate divergence in community structure (beta-diversity) compared to controls. Specific clades and taxa were consistently and significantly modified in the WA animals. The WA microbiome was particularly enriched in Proteobacteria and depleted in several probiotic taxa (including Akkermansia muciniphila). The WA microbiome exhibited a decreased capacity for metabolic domains, including energy- and lipid-metabolism, and an increased capacity for fatty acid and sulfur metabolism. The stressed condition favored the proliferation of a greater diversity of functionally similar microbes, resulting in a functionally poorer microbiome with implications for epithelial health. Microbial sulfur metabolism is implicated in visceral nerve sensitization and should be further investigated as a target metabolic domain in microbial ecological restoration.

Scientific Focus Area: Microbiology and Infectious Diseases

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