Isoleucine attenuates infection induced by E. coli challenge through modulation of intestinal endogenous antimicrobial peptide expression and inhibition of the increase of plasma endotoxin and IL-6 in weaned pigs
Enteric infection is a major cause of morbidity and mortality in both humans and animals worldwide. Immunotherapy against intestinal infection is a well-known antibiotic alternative strategy. Herein, we demonstrated that isoleucine significantly suppressed the multiplication of E. coli in the presence of IPEC-J2 cells. Isoleucine supplementation enhanced concentrations of total plasma protein and IgA of pigs compared with alanine control diet, while inhibited the increase of plasma endotoxin and IL-6 contents induced by E. coli challenge. A significant interaction between E. coli challenge and diet treatment was found in red blood cell volume. Isoleucine improved expression of porcine β-defensin-1 (pBD-1), pBD-2, pBD-3, pBD-114 and pBD-129 in jejunum and ileum of pigs with or without E. coli challenge. Conclusively, Isoleucine attenuated the infection caused by E. coli challenge possibly through increasing intestinal β-defensin expression and inhibiting the increase of plasma endotoxin and IL-6 in weaned pigs.