Fermentable Fibers Enhance Aspects of Innate and Adaptive Immunity in Piglets infected with Salmonella Typhimurium.

OBJECTIVE: To test the hypothesis that fermentable fiber prevents Salmonella typhimurium infection-associated symptoms by enhancing innate and adaptive immune system in neonatal pigs. METHODS: Two-d-old piglets (n=120) were randomized to receive either a nutritionally complete sow milk replacer formula (CON), or supplemented with methylcellulose (MCEL-non-fermentable), soy polysaccharides (SPS-moderately fermentable), or fructooligosaccharides (FOS-highly fermentable). On d7, piglets received an oral gavage of S. typhimurium-798, and continued receiving the same diets up to 48h post-infection. Ileal mucosal samples were obtained for further analyses. RESULTS: A reduction in chloride secretion was observed in FOS when compared to other diets (p<0.0003). The number of ileal sulfo-acidomucins was higher (p<0.05) in FOS before infection compared with other diets. NFkB was inhibited in FOS following infection (p<0.05), when compared with CON. IL-1ß expression was increased at 4h post-infection (p<0.05) in CON; however, this response was attenuated in the fiber groups. IL-6 expression was higher (p<0.05) in CON post- infection, higher in SPS at 24h (p<0.05), but unchanged in MCEL and FOS when compared to pre-infection values. FOS had a higher expression of neutrophil-chemoattractant IL-8 before infection (p<0.05) compared to other groups. CONCLUSION: The reduction in chloride secretion, proinflammatory cytokines expression and NFkB activation, and increased number of sulfo-acidomucins, and IL-8 expression in the fiber groups, indicates that the degree of fermentability impacts the innate and adaptive immune system, and could be the mechanisms by which dietary fibers reduce S. typhimurium infection-associated-symptoms in neonatal pigs and apply these results to infants.

Neutrophil and small intestinal lymphocyte migration after Salmonella typhimurium infection: impact of fermentable fiber.

OBJECTIVES: Formula-fed infants have more episodes of acute diarrhea and intestinal infection than do breast-fed infants. Nutrient additions to infant formula that could confer some of the immune benefits of breast milk to formula-fed infants are currently under investigation. This study examined the impact of enteral formulas supplemented with fermentable substrates on small intestinal lymphocyte and neutrophil migration in piglets infected with Salmonella typhimurium. Small intestinal proinflammatory cytokine messenger RNA abundance and in vitro lipopolysaccharide-stimulated interleukin-6 release in whole blood were assessed. METHODS: Piglets were randomized to receive sow milk replacer formula supplemented with methylcellulose (control), soy polysaccharides (SPS) or fructooligosaccharides (FOS). On day 7, half of the piglets were infected with S. typhimurium. Intestinal lymphocyte, neutrophil and whole blood samples were obtained on day 14. RESULTS: After infection, there was decreased lymphocyte migration in the control group but not in the SPS and FOS groups. The SPS group had greater neutrophil migration compared with the control and FOS groups, regardless of infection. Small intestinal abundance of proinflammatory cytokine messenger RNA was not significantly changed by either infection or diet. Blood from the FOS group challenged with lipopolysaccharide for 2 hours exhibited decreased interleukin-6 production compared with blood from the control and SPS groups, regardless of infection. CONCLUSIONS: Supplementation of enteral formulas with SPS maintains the migratory function of small intestinal lymphocytes while increasing that of neutrophils.

Fermentable fiber reduces recovery time and improves intestinal function in piglets following Salmonella typhimurium infection.

Diarrhea is a leading cause of morbidity and mortality in infants. The addition of fiber to infant formulas reduces recovery time following pathogenic infection in infants > 6 mo old, but effects on neonates are unknown. The hypothesis that fermentable fiber reduces infection-associated symptoms and enhances intestinal structure and function in neonates was examined. Piglets (2 d old) were randomly assigned to receive formula alone (control) or formula containing methylcellulose (MCEL), soy polysaccharides (SPS) or fructooligosaccharides (FOS) for 14 d. On d 7, piglets were further randomly assigned to receive an oral gavage of Salmonella typhimurium or serve as noninfected controls. S. typhimurium infection produced diarrhea in controls and MCEL groups, but not in the SPS and FOS groups. Postinfection physical activity was lower (P = 0.0001) in the controls than in all other groups. Ileal lactase activity was reduced (P < 0.05) following infection in the control group but not in the MCEL, SPS and FOS groups. Ileal mucosal barrier function, measured as resistance, was impaired by infection (P < 0.05) in the control and SPS groups, but was unaltered in the jejunum and colon. Total ion transport and basal short-circuit current were higher (P < 0.05) in jejunum than in ileum and colon, irrespective of diet or infection. SPS and FOS increased (P < 0.05) ileal glutamine transport relative to piglets fed MCEL, irrespective of infection. Because fermentable fiber enhances intestinal function and reduces the severity of S. typhimurium infection-associated symptoms, it may be a cost-effective way in which to reduce the severity of pathogenic infection-associated symptoms in infants.