Abstract
Background Identifying the connection among diet, the intestinal microbiome, and host health is currently an area of intensive research, but the potential of dietary fiber (DF) consumption to ameliorate intestinal inflammation has not been extensively studied. We examined the impacts of the DFs, wheat bran (WB) and resistant starch (RS) on host enteric health. A murine model of acute Th1/Th17 colitis (i.e. incited by Citrobacter rodentium) was used.ResultsDiets enriched with RS increased weight gain in mice inoculated with C. rodentium compared to mice consuming a conventional control (CN) diet. Short-chain fatty acid (SCFA) quantities in the cecum and distal colon were higher in mice consuming DFs, and these mice exhibited higher butyrate concentrations in the distal colon during inflammation. Histopathologic scores of inflammation in the proximal colon on day 14 post-inoculation (p.i.) (peak infection) and 21 p.i. (late infection) were lower in mice consuming DF-enriched diets compared to the CN diet. Consumption of WB reduced the expression of Th1/Th17 cytokines. As well, the expression of bacterial recognition and response genes such as Relmβ, RegIIIγ, and Tlr4 increased in mice consuming the RS-enriched diets. Furthermore, each diet generated a region-specific bacterial community, suggesting a link between selection for specific bacterial communities, SCFA concentrations, and inflammation in the murine colon.ConclusionsCollectively, data indicated that the consumption of DF-rich diets ameliorates the effects of C. rodentium-induced enteritis by modifying the host microbiota to increase SCFA production, and bacterial recognition and response mechanisms to promote host health. Electronic supplementary materialThe online version of this article (doi:10.1186/s13099-016-0149-6) contains supplementary material, which is available to authorized users.
Highlights
Identifying the connection among diet, the intestinal microbiome, and host health is currently an area of intensive research, but the potential of dietary fiber (DF) consumption to ameliorate intestinal inflammation has not been extensively studied
Citrobacter rodentium incited enteritis The presence of C. rodentium was not detected in the feces of mice inoculated with phosphate buffered saline (PBS)
Mice consuming the wheat bran (WB) and resistant starch (RS) diets shed the highest amount of C. rodentium on day 7 p.i., while mice ingesting the control (CN) diet shed the highest counts of C. rodentium on day 10 p.i. (Fig. 1)
Summary
Identifying the connection among diet, the intestinal microbiome, and host health is currently an area of intensive research, but the potential of dietary fiber (DF) consumption to ameliorate intestinal inflammation has not been extensively studied. We examined the impacts of the DFs, wheat bran (WB) and resistant starch (RS) on host enteric health. The intestine is highly influential to host health and contributes greatly to the balance and regulation of the Jiminez et al Gut Pathog (2016) 8:67 microbiota [4, 5]. Certain enteric bacterial species possess specialized metabolic enzymes that ferment specific forms of DFs, and products of fermentation contribute to the bacterial diversity within the intestinal microbiota [4, 7, 8]. By-products of bacterial fermentation are mainly composed of short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate [9, 10] as well as gases. Acetate and propionate are primarily metabolized in the liver and are important for gluconeogenesis and liponeogenesis [11]. Other putative functions of SCFAs within the intestine include maintaining homeostatic intestinal pH and mucosal osmolarity [10], and influencing mucin production and secretion [13], all of which are considered important for both cellular and microbial functions
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