Salmonella Typhimurium (S. Typhimurium) is a common pathogenic microorganism and poses a threat to the efficiency of poultry farms. As signaling molecules regulating the interaction between the host and gut microbiota, bile acids (BAs) play a protective role in maintaining gut homeostasis. However, the antibacterial effect of BAs on Salmonella infection in broilers has remained unexplored. Therefore, the aim of this study was to investigate the potential role of feeding BAs in protecting against S. Typhimurium infection in broilers. A total of 144 1-day-old Arbor Acres male broilers were randomly assigned to 4 groups, including non-challenged birds fed a basal diet (CON), S. Typhimurium-challenged birds (ST), S. Typhimurium-challenged birds treated with 0.15 g/kg antibiotic after infection (ST-ANT), and S. Typhimurium-challenged birds fed a basal diet supplemented with 350 mg/kg of BAs (ST-BA). BAs supplementation ameliorated weight loss induced by S. Typhimurium infection and reduced the colonization of Salmonella in the liver and small intestine in broilers (P < 0.05). Compared to the ST group, broilers in ST-BA group had a higher ileal mucosal thickness and villus height, and BAs also ameliorated the increase of diamine oxidase (DAO) level in serum (P < 0.05). It was observed that the mucus layer thickness and the number of villous and cryptic goblet cells (GCs) were increased in the ST-BA group, consistent with the upregulation of MUC2 gene expression in the ileal mucosa (P < 0.05). Moreover, the mRNA expressions of Toll-like receptor 5 (TLR5), Toll-like receptor 4 (TLR4), and interleukin 1 beta (IL1b) were downregulated in the ileum by BAs treatment (P < 0.05). 16S rDNA sequencing analysis revealed that, compared to ST group, BAs ameliorated the decreases in Bacteroidota, Bacteroidaceae and Bacteroides abundances, which were negatively correlated with serum DAO activity, and the increases in Campylobacterota, Campylobacteraceae and Campylobacter abundances, which were negatively correlated with body weight but positively correlated with serum D-lactic acid (D-LA) levels (P < 0.05). Dietary BAs supplementation strengthens the intestinal mucosal barrier and reverses dysbiosis of gut microbiota, which eventually relieves the damage to the intestinal barrier and weight loss induced by S. Typhimurium infection in broilers.

中文翻译：

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膳食胆汁酸补充剂通过改善肉鸡的肠道粘膜屏障和肠道微生物群组成来预防鼠伤寒沙门氏菌感染


鼠伤寒沙门氏菌 （S. Typhimurium） 是一种常见的病原微生物，对家禽养殖场的效率构成威胁。作为调节宿主与肠道菌群之间相互作用的信号分子，胆汁酸 （BAs） 在维持肠道稳态方面起着保护作用。然而，BAs 对肉鸡沙门氏菌感染的抗菌作用仍未得到探索。因此，本研究的目的是探讨饲喂 BAs 在预防肉鸡鼠伤寒沙门氏菌感染方面的潜在作用。共将 144 只 1 日龄 Arbor Acres 雄性肉鸡随机分为 4 组，包括饲喂基础日粮 （CON） 的非攻击鸡、鼠伤寒沙门氏菌攻击鸡 （ST）、感染后用 0.15 g/kg 抗生素处理的鼠伤寒沙门氏菌攻击鸡 （ST-ANT） 和饲喂补充 350 mg/kg BAs 的基础日粮 （ST-BA） 的鼠伤寒沙门氏菌攻击鸡。补充 BAs 可改善鼠伤寒沙门氏菌感染引起的体重减轻，并减少沙门氏菌在肉鸡肝脏和小肠中的定植 （P < 0.05）。与 ST 组相比，ST-BA 组肉鸡的回肠粘膜厚度和绒毛高度较高，BAs 也改善了血清中二胺氧化酶 （DAO） 水平的升高 （P < 0.05）。观察到 ST-BA 组粘液层厚度和绒毛和隐匿杯状细胞 （GCs） 数量增加，与回肠粘膜中 MUC2 基因表达的上调一致 （P < 0.05）。此外，BAs 处理下调回肠中 Toll 样受体 5 （TLR5） 、 Toll 样受体 4 （TLR4） 和白细胞介素 1 β （IL1b） 的 mRNA 表达 （P < 0.05）。 16S rDNA 测序分析显示，与 ST 组相比，BAs 改善了拟杆菌科、拟杆菌科和拟杆菌属丰度的降低，这些水平与血清 DAO 活性呈负相关，弯曲杆菌科和弯曲杆菌属丰度的增加，这些水平与体重呈负相关，但与血清 D-乳酸 （D-LA） 水平呈正相关（P < 0.05）。膳食 BAs 补充剂可增强肠道粘膜屏障并逆转肠道菌群失调，最终缓解肉鸡鼠伤寒沙门氏菌感染对肠道屏障的损害和体重减轻。