Ferulic acid mediates microbial fermentation of arabinoxylan to enhance host immunity by suppressing TLR4/NF-κB signaling.

The study was conducted to explore the relationship between arabinoxylan (AX) structure and microbial fermentation characteristics, and reveal molecular mechanism of AX on regulating immune function of the host. Results indicated that the group of wheat bran AX showed greater activity of feruloyl esterase, production of short chain fatty acids and ferulic acid compared with the blank group (P < 0.05). The AX increased sIgA concentration and protein expression of protein expression of TLR4 and NF-κB (p65), but decreased mRNA expression of pro-inflammatory cytokines in the ileum of weaned pig model, leading to the reduced diarrhea (P < 0.05). The AX increased an abundance of Bifidobacterium pseudocatenulatum, production of butyric acid and ferulic acid in the ileal digesta of pigs (P < 0.05). In a LPS-treated mouse model, butyric acid and ferulic acid combination increased IL-10 concentration and abundance of Bifidobacterium pseudocatenulatum, but reduced mRNA expression of IL-6 and gene expression of TLR4 and NF-κB (p65) in the jejunum. In summary, AX is fermented by gut microbiota to produce ferulic acid, as well as butyric acid, which improved host immunity by promoting relative abundance of Bifidobacterium pseudocatenulatum and suppressing activation of TLR4/NF-κB signaling.