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.