Purified Diets Lacking Fermentable Fiber Reduce Microbial Diversity, Alter Epithelial Transcriptome, and Exacerbate...

Area of Science:

• Microbiome research
• Gastroenterology
• Nutritional science

Background:

• Dietary fibers significantly influence gut microbiome composition and intestinal homeostasis.
• Purified diets lack the complex fiber mixtures found in standard chow, potentially impacting experimental outcomes.
• Fermentable fibers are hypothesized to be essential for maintaining gut health and preventing inflammation.

Purpose of the Study:

• To investigate the impact of fermentable fiber exclusion on gut microbiome, metabolites, and colonic epithelial gene expression.
• To determine if a purified diet lacking fermentable fiber increases susceptibility to chemically induced colitis.
• To elucidate the role of fermentable fibers in maintaining intestinal homeostasis.

Main Methods:

• Mice were fed either a standard grain-based chow or a purified low-fat diet (LFD) with non-fermentable cellulose for ten weeks.
• Analysis included fecal microbiome sequencing, short-chain fatty acid (SCFA) profiling, and colonic epithelial transcriptomics.
• Colitis was induced using dextran sodium sulfate (DSS) to compare disease severity between diet groups.

Main Results:

• The LFD group exhibited reduced microbial diversity and significantly lower SCFA levels compared to the chow group.
• Colonic epithelial transcriptomes showed distinct alterations, with upregulated ribosomal and MHC pathways and downregulated mineral absorption and cellular transport pathways in the LFD group.
• LFD-fed mice displayed increased colonic S100a9 expression and exacerbated DSS-induced colitis.

Conclusions:

• Fermentable fibers are vital for maintaining gut microbial diversity and SCFA production.
• Absence of fermentable fiber in purified diets alters colonic epithelial cell function and increases inflammation.
• Dietary fermentable fibers play a protective role against ulcerative colitis development and severity.