Key Laboratory for Animal Disease Resistance Nutrition of the Ministry of Education, Animal Nutrition Institute, Sichuan Agricultural University, Chengdu611130, People's Republic of China.
Sericultural & Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou510610, People's Republic of China.
Br J Nutr. 2020 Oct 28;124(8):797-808. doi: 10.1017/S0007114520001774. Epub 2020 May 21.
Bile acids (BA) have emerged as signalling molecules regulating intestinal physiology. The importance of intestinal microbiota in production of secondary BA, for example, lithocholic acid (LCA) which impairs enterocyte proliferation and permeability, triggered us to determine the effects of oral probiotics on intestinal BA metabolism. Piglets were weaned at 28 d of age and allocated into control (CON, n 14) or probiotic (PRO, n 14) group fed 50 mg of Lactobacillus plantarum daily, and gut microbiota and BA profile were determined. To test the potential interaction of LCA with bacteria endotoxins in inducing damage of enterocytes, IPEC-J2 cells were treated with LCA, lipopolysaccharide (LPS) and LCA + LPS and expressions of genes related to inflammation, antioxidant capacity and nutrient transport were determined. Compared with the CON group, the PRO group showed lower total LCA level in the ileum and higher relative abundance of the Lactobacillus genus in faeces. In contrast, the relative abundances of Bacteroides, Clostridium_sensu_stricto_1, Parabacteroides and Ruminococcus_1, important bacteria genera in BA biotransformation, were all lower in the PRO than in the CON group. Moreover, PRO piglets had lower postprandial glucagon-like peptide-1 level, while higher glucose level than CON piglets. Co-administration of LPS and LCA led to down-regulated expression of glucose and peptide transporter genes in IPEC-J2 cells. Altogether, oral L. plantarum altered BA profile probably by modulating relative abundances of gut microbial genera that play key roles in BA metabolism and might consequently impact glucose homoeostasis. The detrimental effect of LCA on nutrient transport in enterocytes might be aggravated under LPS challenge.
胆汁酸（BA）已成为调节肠道生理的信号分子。例如，肠道微生物在次级 BA（如石胆酸，LCA）生成中的重要性，LCA 会损害肠细胞的增殖和通透性，这促使我们确定口服益生菌对肠道 BA 代谢的影响。仔猪在 28 日龄断奶，分为对照组（CON，n=14）或益生菌组（PRO，n=14），每天喂食 50mg 植物乳杆菌，测定肠道微生物群和 BA 谱。为了测试 LCA 与细菌内毒素相互作用诱导肠细胞损伤的潜力，用 LCA、脂多糖（LPS）和 LCA+LPS 处理 IPEC-J2 细胞，测定与炎症、抗氧化能力和营养转运相关的基因表达。与 CON 组相比，PRO 组回肠总 LCA 水平较低，粪便中乳杆菌属相对丰度较高。相比之下，BA 生物转化的重要细菌属如梭菌属（Clostridium_sensu_stricto_1）、拟杆菌属（Parabacteroides）、真杆菌属（Ruminococcus_1）的相对丰度在 PRO 组均低于 CON 组。此外，PRO 仔猪餐后胰高血糖素样肽-1 水平较低，血糖水平高于 CON 仔猪。LPS 和 LCA 共同给药导致 IPEC-J2 细胞中葡萄糖和肽转运基因表达下调。总之，口服植物乳杆菌可能通过调节在 BA 代谢中起关键作用的肠道微生物属的相对丰度来改变 BA 谱，从而可能影响葡萄糖稳态。LCA 对肠细胞中营养物质转运的有害影响在 LPS 挑战下可能会加剧。
