Influence of Lactobacillus fermentum I5007 on the intestinal and systemic immune responses of healthy and E. coli challenged piglets.

The effect of feeding Lactobacillus fermentum I5007 on the immune system of weaned pigs with or without E. coli challenge was determined. Twenty-four weaned barrows (6.07 +/- 0.63 kg BW) were randomly assigned to one of four treatments (N = 6) in a factorial design experiment. The first two treatments consisted of healthy piglets with half of the pigs receiving no treatment while the other half was orally administered with L. fermentum I5007 (10(8) CFU/ml) at a daily dose of 20 ml. Pigs in the second two treatments were challenged on the first day with 20 ml of E. coli K88ac (10(8) CFU/ml). Half of these pigs were not treated while the remaining pigs were treated with 20 ml of L. fermentum I5007 (10(8) CFU/ml). Peripheral blood lymphocytes subsets were determined using flow cytometry. The intestinal mucosal immunity of the pigs was monitored by real time polymerase chain reaction. The cytokine content of the pig's serum was also analyzed. Oral administration of L. fermentum I5007 increased blood CD4(+) lymphocyte subset percentage as well as tumor necrosis factor-alpha and interferon-gamma expression in the ileum. Pigs challenged with E. coli had elevated jejunal tumor necrosis factor-alpha while interferon-gamma expression was increased throughout the small intestine. There was no difference in the concentration of the cytokines interleukin-2, interleukin-6, tumor necrosis factor-alpha and interferon-gamma in the serum. CD8(+) and CD4(+)/CD8(+) in peripheral blood were not affected by treatment. In conclusion, L. fermentum I5007 can enhance T cell differentiation and induce ileum cytokine expression suggesting that this probiotic strain could modulate immune function in piglets.