State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
Microbiome. 2022 May 28;10(1):79. doi: 10.1186/s40168-022-01269-0.
Antimicrobials are often used to prevent and treat diarrhea induced by enteroaggregative Escherichia coli (EAEC) in young ruminants. However, drug overuse or misuse accelerates the spread of multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing E. coli. Thus, supplementary foods as alternatives to antibiotics are needed to prevent colibacillus diarrhea in neonatal dairy calves. Ursodeoxycholic acid (UDCA), a therapeutic bile acid, helps alleviate colitis. However, how UDCA helps alleviate ESBL-EAEC-induced clinical symptoms and colitis remains unclear.
We investigated the microbial profiles and metabolites of healthy and diarrheic neonatal calves to determine microbial and metabolite biomarkers in early-life development. Both the gut microbiota communities and their associated metabolites differed between healthy and diarrheic calves. Commensal Butyricicoccus, Faecalibacterium, Ruminococcus, Collinsella, and Coriobacterium were key microbial markers that distinguished healthy and diarrheic gut microbiomes. Random forest machine-learning algorithm and Spearman correlation results indicated that enriched UDCA, short-chain fatty acids (SCFAs), and other prebiotics were strongly positively correlated with these five bacterial genera. We explored the effect of ursodiol on bacterial growth, cell adherence, and lipopolysaccharide-treated Caco-2 cells. Adding ursodiol induced direct antibacterial effects, suppressed proinflammatory effects, and reduced cell integrity damage. Oral ursodiol delivery to neonatal mice exhibited significant antibacterial effects and helped maintain colonic barrier integrity in mouse models of peritonitis sepsis and oral infection. UDCA supplementation attenuated colitis and recovered colonic SCFA production. To validate this, we performed fecal microbiota transplantations to inoculate ESBL-EAEC-infected neonatal mice. Microbiotas from UDCA-treated neonatal mice ameliorated colitis and hindgut commensal bacterial damage compared with that of the microbiotas from the control and placebo mice, as evidenced by colonization of abundant bacteria, including Oscillospiraceae, Ruminococcaceae, Lachnospiraceae, and Clostridia_UCG-014, and upregulated SCFA production.
This study provided the first evidence that UDCA could confer diarrhea resistance in ESBL-EAEC-infected newborn dairy calves. UDCA blocked bacterial growth and invasion both in vitro and in vivo, alleviated commensal bacterial dysbiosis during ESBL-EAEC infection in neonatal mouse models of sepsis and colitis via the TGR5-NF-κB axis, and upregulated SCFA production in the hindgut digesta. Our findings provide insight into the UDCA-mediated remission of ESBL-EAEC infections and the potential role of UDCA as an antibiotic alternative. Video abstract.
抗菌药物常被用于预防和治疗幼反刍动物中聚集性大肠埃希菌（EAEC）引起的腹泻。然而，药物的过度使用或滥用会加速产生多药耐药性扩展谱β-内酰胺酶（ESBL）-产大肠埃希菌的传播。因此，需要替代抗生素的补充食品来预防新生奶牛的大肠杆菌腹泻。熊去氧胆酸（UDCA）是一种治疗性胆汁酸，有助于缓解结肠炎。然而，UDCA 如何帮助缓解 ESBL-EAEC 引起的临床症状和结肠炎尚不清楚。
我们研究了健康和腹泻新生小牛的微生物谱和代谢物，以确定生命早期发育过程中的微生物和代谢物生物标志物。健康和腹泻小牛的肠道微生物群落及其相关代谢物不同。共生丁酸球菌、粪杆菌、瘤胃球菌、柯林斯菌和考里氏菌是区分健康和腹泻肠道微生物组的关键微生物标志物。随机森林机器学习算法和 Spearman 相关结果表明，富含 UDCA、短链脂肪酸（SCFAs）和其他益生元与这五个细菌属呈强烈正相关。我们探讨了熊去氧胆醇对细菌生长、细胞黏附和脂多糖处理的 Caco-2 细胞的影响。添加熊去氧胆醇诱导直接抗菌作用，抑制促炎作用，并减少细胞完整性损伤。向新生小鼠口服熊去氧胆醇表现出显著的抗菌作用，并有助于维持腹膜炎败血症和口服感染模型中小鼠的结肠屏障完整性。UDCA 补充剂可减轻结肠炎并恢复结肠 SCFA 产生。为了验证这一点，我们进行了粪便微生物移植以接种 ESBL-EAEC 感染的新生小鼠。与对照和安慰剂小鼠的微生物群相比，来自 UDCA 治疗的新生小鼠的微生物群改善了结肠炎和回肠共生细菌损伤，这表现在大量细菌的定植，包括 Oscillospiraceae、Ruminococcaceae、Lachnospiraceae 和 Clostridia_UCG-014，以及上调的 SCFA 产生。
本研究首次提供了 UDCA 可赋予 ESBL-EAEC 感染新生奶牛腹泻抗性的证据。UDCA 阻断了细菌的生长和入侵，无论是在体外还是体内，通过 TGR5-NF-κB 轴减轻了新生小鼠败血症和结肠炎模型中 ESBL-EAEC 感染期间共生细菌的失调，并上调了回肠内容物中的 SCFA 产生。我们的研究结果为 UDCA 介导的 ESBL-EAEC 感染缓解提供了新的见解，并为 UDCA 作为抗生素替代品的潜在作用提供了新的见解。视频摘要。
