Diets containing different fermentable substrates can affect mucosal and systemic immune parameters in rats under homeostatic conditions

The effect of diets containing different fermentable substrates (resistant starch (RS), oat bran (OB) or wheat bran (WB)) on immune parameters in rat gastrointestinal and systemic tissues under homeostatic immune conditions was examined. Only the diet containing WB altered T and B cell populations in mesenteric lymph nodes (MLN) and spleen. Analysis of tissue cytokine profiles showed ileal cytokine-induced neutrophil chemoattractant (CINC)-1, interleukin 4 (IL-4), IL-10 and transforming growth factor (TGF)-β1 levels increased in rats fed WB, whereas CINC-1, IL-6, and TGF-β1 levels were highest in the colon of OB-fed rats. In the liver, levels of TGF-β1 increased in rats fed diets containing RS or OB. Sex-based differences in immune parameters were observed in rats fed WB. It is apparent that different dietary fermentable substrates have distinct effects on immune activity under homeostatic conditions. These findings provide new insight into immunological outcomes associated with fibres and starches as dietary supplements.