Effects of Dietary Astragalus Polysaccharide Supplementation on the Th17/Treg Balance and the Gut Microbiota of Broiler Chickens Challenged With Necrotic Enteritis

Abstract

This study aimed to investigate the effects of dietary astragalus polysaccharide (APS) supplementation on the immune function, gut microbiota and metabolism of broiler chickens challenged with necrotic enteritis (NE). Two hundred forty Arbor Acres broiler chicks (one day old) were randomly assigned using a 2 × 2 factorial arrangement into two groups fed different levels of dietary APS (0 or 200 ppm of diet) and two disease challenge groups (control or NE challenged). The results showed that NE infection significantly increased FCR, mortality rate, Th17/Treg (Th17 cells% in blood and ileum, Th17/Treg, IL-17 and IL-17/IL-10 in blood), NO, lysozyme activity and IL-1β in blood, intestinal immune cell proportion and activity (Tc%, Treg% and monocyte phagocytic activity in ileum), intestinal inflammatory cytokines (TLR2, NF-κB, TNF-α and IL- 6) gene expression levels, and the number of Clostridium perfringens in cecum. NE infection significantly reduced body weight gain, thymus index, lymphocyte proliferation activity in blood and ileum, villus height and V/C in jejunum, Th cells% and Mucin2 gene expression in ileum. Dietary APS supplementation significantly increased body weight, feed intake, proportion of immune cells (T cells in blood and Tc, Treg in ileum), lymphocyte proliferation activity, V/C in jejunum, and ZO-1 gene expression in ileum. Dietary APS supplementation significantly reduced FCR and mortality rate, Th17/Treg, Th17%, intestinal pathology scores, intestinal inflammatory cytokine gene expression levels, and the number of Clostridium perfringens in cecum. In addition, broilers challenged with NE significantly increased Staphylococcus and Turicibacter and reduced α diversity of microbiota in ileum. Dietary APS supplementation significantly increased α diversity, Romboutsia, Halomonas, propionic acid, butyric acid, formononetin, taurine, cholic acid and equol and downregulated uric acid, L-arginine and serotonin in ileum. Spearman’s correlation analysis revealed that Romboutsia, Turicibacter, Staphylocpccus, Halomonas, Streptococcus, Escherichia-Shigella, Prevotella, uric acid, L-arginine, jerivne, sodium cholate and cholic acid were related to inflammation and Th17/Treg balance. In conclusion, APS alleviated intestinal inflammation in broilers challenged with NE probably by regulating intestinal immune, Th17/Treg balance, as well as intestinal microbiota and metabolites.

Supplementation with paraformic acid in the diet improved intestinal development through modulating intestinal inflammation and microbiota in broiler chickens

“…Gut dysbiosis and gastrointestinal inflammatory disease are usually characterized by reduced bacterial richness (Clemente et al, 2018). The results in Song et al (2022) showed that necrotic enteritis challenge increased intestinal inflammatory cytokine gene expression levels, inhibited intestinal development, and caused intestinal damage, as well as reduced alpha diversity of microbiota in ileum of broilers. Bacteroidetes and Firmicutes were the most predominant phyla in cecal samples of broilers in this study, which was in accord with the results of previous study (Cui et al, 2021).…”

Quercetin Reduces Inflammation and Protects Gut Microbiota in Broilers

“…The quantitative changes in some specific bacteria in the present study were supported by previous studies. Studies have pointed out that the abundance levels of Halomonas , Peptococcus , and Rubrobacter can be associated with intestinal inflammation, and are increased when intestinal inflammation occurs [ 36 , 37 , 38 ]. Streptomyces and Micromonospora , as members of Actinobacteria , have been shown to have anti-inflammatory and antioxidant effects [ 39 , 40 , 41 ].…”

Abietic acid attenuates LPS-induced acute lung injury by restoring Th17/Treg balance

“…Tregs secrete anti-inflammatory mediators to maintain immune homeostasis [13]. Imbalances in Th and Treg cells contribute to the development of various diseases [14]. Restoration of the balance of Th17 cells and Treg cells has been shown to improve ALI [15].…”