芍药苷对结肠炎小鼠肠道菌群及胆汁酸代谢的调节作用

Paeoniflorin regulates gut microbiota and bile acids metabolism in colitis mice

本研究旨在探讨芍药苷对结肠炎小鼠肠道菌群失调及胆汁酸代谢紊乱的调节作用及相关机制。经西安交通大学伦理委员会审议同意并批准后(批准号:XJTU2019-679),采用3%右旋葡聚糖硫酸钠(DSS)诱导急性结肠炎小鼠模型,同时给药组连续灌胃芍药苷(25、50 mg·kg^(-1)·d^(-1))或5-氨基水杨酸(50 mg·kg^(-1)·d^(-1))7天。实验期间每日监测小鼠体重、粪便黏稠度及便血情况。采用HE染色观察结肠组织病理改变,ELISA检测结肠炎性因子,荧光素异硫氰酸酯(FITC)-葡聚糖检测肠通透性,16S rDNA高通量测序分析肠道菌群组成,最后采用靶向胆汁酸代谢组学方法检测粪便中胆汁酸分子含量的变化。结果表明:芍药苷显著抑制了结肠炎小鼠结肠组织中致炎因子TNF-α、IL-1β、IL-6的水平,促进了抑炎因子IL-10的释放;并且芍药苷可降低结肠炎小鼠的肠通透性,改善肠屏障功能损伤。肠道菌群分析结果显示芍药苷显著改善了DSS引起的小鼠肠道菌群紊乱,尤其提高乳酸杆菌的相对丰度,降低拟杆菌的相对丰度。此外,芍药苷治疗后显著逆转结肠炎小鼠粪便中胆汁酸分子的代谢紊乱(主要包括胆酸、脱氧胆酸、石胆酸以及β-鼠胆酸)。最后,对肠道菌属与粪便中胆汁酸分子水平进行相关性分析发现,乳酸杆菌与具有维持肠道稳态作用的脱氧胆酸和石胆酸呈显著正相关。因此,芍药苷可能通过重塑结肠炎小鼠肠道菌群结构,调节菌群介导的胆汁酸代谢紊乱,进而修复肠屏障损伤、降低肠道炎症,最后对结肠炎小鼠发挥保护作用。

The current study was designed to evaluate the modulatory effects of paeoniflorin on the dysregulated gut microbiota as well as the disturbed fecal bile acids(BAs)in colitis mice.After approved by Xi'an Jiaotong University Ethics Committees(Approval No.XJTU2019-679),the animals were randomly distributed into the control(Con),colitis,low dose paeoniflorin(PF-L,25 mg·kg^(-1)·d^(-1)),high dose paeoniflorin(PF-H,50 mg·kg^(-1)·d^(-1))and 5-aminosalicylic acid(5-ASA,50 mg·kg^(-1)·d^(-1))groups.Colitis was induced by administering 3%(w/v)DSS in drinking water for 7 days.Paeoniflorin and 5-ASA were dissolved in water and administered to the appropriate groups by oral gavage over the 7-day period.The mice were monitored daily,and the disease activity index(DAI)comprising of body weight loss,stool consistency and gross blood was measured.The pathological changes of colon were evaluated by HE staining;the levels of inflammatory cytokines in colonic tissue were determined by ELISA;the gut permeability was measured by FITC-dextran.Microbiota analysis based on 16S rDNA and targeted metabolomics for BAs were used to evaluate the composition of gut microbiota and fecal BAs pool.The results showed that administration of paeoniflorin markedly alleviated the inflammatory response and intestinal barrier dysfunction in DSS-induced colitis.Importantly,these ameliorative effects of paeoniflorin were accompanied by the improvements of disturbed composition of gut microbiota and the dysmetabolism of bile acids in feces.Finally,we performed Spearman's correlation analysis between the fecal BAs and gut microbiota genera,and found that Lactobacillus has a strong positive correlation with DCA and LCA which were reported to confer the beneficial effects of maintaining intestinal homeostasis.Taken together,paeoniflorin might improve the intestinal homeostasis in colitis mice via modulating gut microbiota and fecal BAs metabolism.