Amelioration of Enterotoxigenic Escherichia coli-induced disruption of intestinal epithelium by Manno-oligosaccharide in weaned pigs

Abstract Background: Enterotoxigenic Escherichia coli (ETEC) is one of the major bacterial causes leading to diarrhea and disruption of intestinal epithelium in neonatal animals. Manno-oligosaccharide (MOS) is a prebiotic deprived from natural plants or yeasts. Here, we explored the protective effect of MOS on intestinal epithelium in weaned pigs upon ETEC challenge. Methods: Thirty-two pigs were randomly assigned into four treatments and fed with a basal diet or basal diet containing 0.3% MOS. On day 19, pigs were challenged by ETEC or culture medium. Results: MOS supplementation reduced diarrhea incidence in the pigs upon ETEC challenge (P<0.05). ETEC-challenge elevated the serum concentrations of D-lactate and diamine oxidase (DAO), however, MOS significantly decreased their concentrations in the serum (P<0.05). Moreover, MOS significantly decreased serum concentrations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the ETEC-challenged pigs (P<0.05). Interestingly, MOS enhanced the expression and localization of zonula occludens-1 (ZO-1) protein in the duodenal and jejunal epithelium. Moreover, MOS decreased the cell apoptosis rate (P<0.05), but significantly elevated the content of secretory immunoglobulin A (sIgA), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) in the jejunal mucosa (P<0.05). Importantly, MOS decreased the expression levels of critical genes involving in mucosal inflammatory responses (TNF-α, IL-1β, TLR4, and NF-κB) and the apoptosis (Caspase 3, Caspase 9, and Bax) in the jejunum upon ETEC challenge (P<0.05). Moreover, MOS up-regulated the expression of mucosa functional genes such as the heme oxygenase-1 (HO-1) and nuclear factor E2-related factor 2 (Nrf2) in the jejunum and ileum (P<0.05), and elevated the expression level of β-defensin 114 (PBD-114) in the duodenum upon ETEC challenge. Conclusions: These results suggested that MOS can alleviate ETEC-induced disruption of intestinal barrier in weaned pigs, which was associated with suppressed inflammation and epithelial cell apoptosis, and improved antioxidant capacity and intestinal barrier functions.