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Early weaning usually causes intestinal disorders, enteritis, and diarrhea in young animals and human infants. Astragalus polysaccharides (APS) possesses anti‐inflammatory activity. To study the anti‐inflammatory mechanisms of APS and its potential effects on intestinal health, we performed an RNA sequencing (RNA‐seq) study in lipopolysaccharide (LPS)‐stimulated porcine intestinal epithelial cells (IPEC‐J2) in vitro. In addition, LPS‐stimulated BALB/c mice were used to study the effects of APS on intestinal inflammation in vivo. The results from the RNA‐seq analysis show that there were 107, 756, and 5 differentially expressed genes in the control versus LPS, LPS versus LPS+APS, and control versus LPS+APS comparison groups, respectively. The results of Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the mitogen‐activated protein kinase (MAPK) and nuclear factor‐κB (NF‐κB) signaling pathways play significant roles in the regulation of inflammatory factors and chemokine expression by APS. Further verification of the above two pathways by using western blot and immunofluorescence analysis revealed that the gene expression levels of the phosphorylated p38 MAPK, ERK1/2, and NF‐κB p65 were inhibited by APS, while the expression of IκB‐α protein was significantly increased (p <.05), indicating that APS inhibits the production of inflammatory factors and chemokines by the inhibition of activation of the MAPK and NF‐κB inflammatory pathways induced by LPS stimulation. Animal experiments further demonstrated that prefeeding APS in BALB/c mice can alleviate the expression of the jejunal inflammatory factors interleukin 6 (IL‐6), IL‐Iβ, and tumor necrosis factor‐α induced by LPS stimulation and improve jejunal villus morphology. [ABSTRACT FROM AUTHOR]

Salmonella typhimurium (S. t.) is one of the main pathogens that causes acute gastroenteritis. To evaluate the anti-inflammatory mechanism of Astragalus polysaccharide (APS) in vivo and its influence on the intestinal flora, BALB/c mice were infected with S. t. to establish a model of diarrhea. The disease activity index (DAI) scores showed that APS attenuated S. t.-induced weight loss and diarrhea in mice. APS significantly reduced the index of the liver and spleen as well as the ALT and AST levels in serum (P < 0.05). Hematoxylin and eosin (H&E) results indicated that APS significantly increased jejunum villus height and crypt depth and reduced the infiltration of inflammatory cells (P < 0.05). Additionally, APS increased the tight junction (TJ) proteins expression levels of ZO-1, Occludin and Claudin-1 in the jejunum. The results of 16S rDNA showed that APS significantly increased the number of Lactobacillus and Bifidobacterium spp. to normal levels (compared with the control group). In addition, APS significantly decreased the mRNA expression levels of the proinflammatory cytokines TNF-α, IL-1β, IL-6 and IL-17 in the jejunum (P < 0.01) as well as the proteins expression levels of COX-2 and iNOS (P < 0.05). Western blot confirmed that prefeeding with APS inhibited S. t. -induced expression of TLR4 and MyD88 in the jejunum and further inhibited nuclear factor-κB (NF-κB) activation, including the nuclear translocation of the p65 NF-κB subunit and the phosphorylation and degradation of IκB-α. This was the key to APS inhibition of the production of inflammatory factors and inflammatory mediators in the jejunum. • In our study, APS relieved inflammation through inhibiting body weight loss and reducing the liver and spleen index of infected mice. • APS increased the intestinal barrier function by repairing damaged structures of the jejunum villi and balancing intestinal flora. • PS is expected to be an alternative to antibiotics for the treatment of intestinal inflammation caused by bacterial infections. [ABSTRACT FROM AUTHOR]