Administration of Pediococcus acidilactici or Saccharomyces cerevisiae boulardii modulates development of porcine mucosal immunity and reduces intestinal bacterial translocation after Escherichia coli challenge.

In this study, the influence of the probiotics, Pediococcus acidilactici (PA) and Saccharomyces cerevisiae boulardii (SCB), on intestinal immune traits and resistance to enterotoxigenic Escherichia coli (ETEC) infection was evaluated in pigs. Two weeks before farrowing, 30 sows and their future litters were allocated to the following treatments: 1) control group without antibiotic or probiotic treatment (CTRL), 2) control with antibiotic (tiamulin) added to weanling feed (ABT), or litters treated with 3) PA, 4) SCB, or 5) PA+SCB from 24 h after birth. During lactation, PA, SCB, or PA+SCB were given to piglets 3 times a week by gavage. After weaning at 21 d of age, probiotics or ABT were added to the diet. Four pigs per litter were chosen to evaluate performance and blood concentrations of folic acid and vitamin B(12). Three of these were orally challenged with an ETEC strain on d 49 to 51 and killed on d 52. Three piglets from the rest of the litter were slaughtered on d 18 and 3 others on d 24. Blood, ileum, and mesenteric lymph node (MLN) samples were taken to characterize leukocyte populations, determine IgA concentrations in ileal flushes, and evaluate bacterial translocation in MLN. No treatment effect on postweaning performance and on blood concentrations of folic acid and vitamin B(12) was observed. In the ileum, the percentage of CD4(-)CD8(+low) T cells was greater (P = 0.05) in 18-d-old nursed piglets treated with PA than in those of the CTRL and PA+SCB groups. In the MLN, the percentage of CD8(+) T cells was not affected by any of the treatments at d 18 and 24 but decreased (P = 0.006) after weaning. In the blood, CD8(+) T cells were not affected by treatments or weaning. After the ETEC challenge (d 52), bacterial translocation to MLN was reduced (P = 0.05) in pigs treated with PA, SCB, PA+SCB, or ABT compared with CTRL. No treatment effect was observed on blood leukocyte populations after ETEC challenge, although a time effect (d 42 vs. 52) indicated that blood CD4(+) and gammadelta-T lymphocytes were increased (P < 0.05) on d 52 compared with d 42, whereas CD4(-)CD8(+low) T lymphocytes and monocytes were markedly reduced (P < 0.01). Finally, the IgA concentration in ileal flushes collected on d 42 and 52 was greater in SCB and CTRL piglets than in ABT and PA piglets. In conclusion, probiotics may have the potential to modulate establishment of lymphocyte populations and IgA secretion in the gut and to reduce bacterial translocation to MLN after ETEC infection.