Medium-chain TAG improve intestinal integrity by suppressing toll-like receptor 4, nucleotide-binding oligomerisation domain proteins and necroptosis signalling in weanling piglets challenged with lipopolysaccharide

摘要

This study was conducted to evaluate whether medium-chain TAG (MCT) could alleviate Escherichia coli lipopolysaccharide (LPS)-induced intestinal injury by regulating intestinal epithelial inflammatory response, as well as necroptosis. A total of twenty-four weanling piglets were randomly allotted to one of four treatments in a 2 x 2 factorial arrangement including diet type (5% maize oil v. 4% MCT + 1% maize oil) and immune stress (saline v. E. coli LPS). The piglets were fed diets containing maize oil or MCT for 21 d. On 21 d, piglets were injected intraperitoneally with saline or LPS. The blood and intestinal samples were collected at 4 h post injection. Supplementation with MCT improved intestinal morphology, digestive and barrier function, indicated by increased jejunal villus height, increased jejunal and ileal disaccharidases (sucrase and maltase) activities, as well as enhanced protein expression of claudin-1. Furthermore, the protein expression of heat-shock protein 70 in jejunum and the concentration of TNF-alpha in plasma were reduced in the piglets fed diets supplemented with MCT. In addition, MCT down-regulated the mRNA expression of toll-like receptor 4 (TLR4) and nucleotide-binding oligomerisation domain proteins (NOD) signalling-related genes in jejunum and ileum. Finally, MCT inhibited jejunal and ileal enterocyte necroptosis indicated by suppressed mRNA expression of the receptor-interacting protein 3 and mixed-lineage kinase domain-like protein. These results indicate that MCT supplementation may be closely related to inhibition of TLR4, NOD and necroptosis signalling pathways and concomitant improvement of intestinal integrity under an inflammatory condition.