Monoassociation of Preterm Germ-Free Piglets with Bifidobacterium animalis Subsp. lactis BB-12 and Its Impact on Infection with Salmonella Typhimurium

Abstract

Preterm germ-free piglets were monoassociated with probiotic Bifidobacterium animalis subsp. lactis BB-12 (BB12) to verify its safety and to investigate possible protection against subsequent infection with Salmonella Typhimurium strain LT2 (LT2). Clinical signs of salmonellosis, bacterial colonization in the intestine, bacterial translocation to mesenteric lymph nodes (MLN), blood, liver, spleen, and lungs, histopathological changes in the ileum, claudin-1 and occludin mRNA expression in the ileum and colon, intestinal and plasma concentrations of IL-8, TNF-α, and IL-10 were evaluated. Both BB12 and LT2 colonized the intestine of the monoassociated piglets. BB12 did not translocate in the BB12-monoassociated piglets. BB12 was detected in some cases in the MLN of piglets, consequently infected with LT2, but reduced LT2 counts in the ileum and liver of these piglets. LT2 damaged the luminal structure of the ileum, but a previous association with BB12 mildly alleviated these changes. LT2 infection upregulated claudin-1 mRNA in the ileum and colon and downregulated occludin mRNA in the colon. Infection with LT2 increased levels of IL-8, TNF-α, and IL-10 in the intestine and plasma, and BB12 mildly downregulated them compared to LT2 alone. Despite reductions in bacterial translocation and inflammatory cytokines, clinical signs of LT2 infection were not significantly affected by the probiotic BB12. Thus, we hypothesize that multistrain bacterial colonization of preterm gnotobiotic piglets may be needed to enhance the protective effect against the infection with S. Typhimurium LT2.

Xylo‐oligosaccharide alleviates Salmonella induced inflammation by stimulating Bifidobacterium animalis and inhibiting Salmonella colonization

“…At the same time, the BB12 reduced the abundance of Salmonella in cecal digesta, demonstrating that BB 12 could resist Salmonella colonization on the intestine. Consistently, BB12 and Bifidobacterium boum RP36 and RP37 strains were able to colonize the intestine of germ‐free piglets and without the support of any oxygen‐consuming bacteria 47,48 . The previous association of preterm germ‐free piglets with BB12 downregulated the growth of S .…”

“…In the BB12‐ST group mice were lower concentrations of d ‐lactic acid, suggesting that BB12 may improve the epithelial barrier. Concordantly, no differences in the mRNA expression claudin‐1 and occludin were observed under the influence of B. boum RP36 and RP37 strains or BB12 in S Typhimurium infected germ‐free piglets 47,48 . B. boum strains also had no effects on the relative mRNA expression and secretion of mucin‐2 in S .…”

“…Concordantly, no differences in the mRNA expression claudin-1 and occludin were observed under the influence of B. boum RP36 and RP37 strains or BB12 in S Typhimurium infected germ-free piglets. 47,48 B. boum strains also had no effects on the relative mRNA expression and secretion of mucin-2 in S. Typhimurium infected gnotobiotic piglets. 48 The inflammatory cytokines relative mRNA expression of IL-1β, TNF-α, and CXCL-1 of colonic tissue were lower in the BB12 inoculated mice than in the Salmonella infected mice, as well as IL-1β, IL-6, and TNF-α in colon and serum, suggesting that BB12 reduced inflammatory effects on Salmonella model in mice.…”

“…47,48 The previous association of preterm germ-free piglets with BB12 downregulated the growth of S. Typhimurium in the ileum, its translocation to the liver, and epithelial layer erosion in the ileum. 47 In case of the term gnotobiotic piglets, pig commensal B. boum strain downregulated S. Typhimurium counts in the jejunum, ileum, and colon. However, the mucinolytic B. boum RP36 strain supported the translocation of S. Typhimurium into the blood, liver, and spleen in comparison to non-mucinolytic strain B. boum RP37.…”

“…Consistently, BB12 and Bifidobacterium boum RP36 and RP37 strains were able to colonize the intestine of germ-free piglets and without the support of any oxygen-consuming bacteria. 47,48 The previous association of preterm germ-free piglets with BB12 downregulated the growth of S. Typhimurium in the ileum, its translocation to the liver, and epithelial layer erosion in the ileum. 47 In case of the term gnotobiotic piglets, pig commensal B. boum strain downregulated S. Typhimurium counts in the jejunum, ileum, and colon.…”