Effects of Toona sinensis bark alcohol extract on mucosal barrier and gut microbiota in mice with ulcerative colitis
AIM:To investigate the effects and underlying mechanism of Toona sinensis bark extract(TAE)on the colon mucosal barrier and gut microbiota in mice with ulcerative colitis(UC)induced by dextran sulfate sodium(DSS).METHODS:Sixty C57BL/6J mice were randomly assigned to control,model,and mesalazine(0.2 g/kg)groups,as well as TAE groups(low,medium,and high-doses equal to crude drug concentrations of 2.3,4.6 and 9.2 g/kg,respectively).The UC model was induced by drinking of 2.5％DSS,and mean while the drugs were administered for 10 days.The mice were then evaluated in terms of weight,disease activity index(DAI),colon length,spleen index,and pathological changes in the colon tissues.In addition,the level of apoptosis in colon tissues was assessed by terminal de-oxynucleotidyl transferase dUTP nick-end labeling(TUNEL)fluorescence staining,and the expression of related proteins was evaluated by Western blot,levels of inflammatory factors were determined by enzyme-linked immunosorbent assays(ELISA),and the activities of total superoxide dismutase(T-SOD)and catalase(CAT)and malondialdehyde(MDA)content were assessed by biochemical assays.Furthermore,the constitution and diversity of the gut microbiota were inves-tigated by 16S rRNA gene sequencing.RESULTS:Compared with the control group,mice in the model group showed significantly reduced body weights(P<0.01),and the colon length was shortened significantly(P<0.05).Marked in-creases in the DAI and spleen index were observed(P<0.01),along with severe damage to the colon mucosa(P<0.01).Mechanistically,the level of intestinal epithelial cell apoptosis was significantly raised(P<0.01).The model group showed markedly reduced expression of occludin and claudin-1(P<0.01),the level of IL-10,and activities of T-SOD and CAT in the colon tissues(P<0.01).While the levels of IL-6,IL-1β,TNF-α,and the MDA content were increased signif-icantly(P<0.05).The abundance and diversity of the gut microbiota were decreased in the model group(P<0.05).Com-pared with the model group,all these indicators were ameliorated by the administration of TAE(P<0.05).The abundance of pathogenic bacteria,including Proteobacteria and Escherichia-Shigella,was decreased remarkably(P<0.05),while that of probiotics,including Bacteroidota and Muribaculaceae,were increased significantly(P<0.05).The abundance and diversity of the gut microbiota were increased.CONCLUSION:Taken together,Toona sinensis bark alcohol extract can alleviate damage to the intestinal mucosa by suppressing the apoptosis of intestinal epithelial cell,reducing the inflam-matory response,and mitigating oxidative stress.Treatment with TAE could also maintain the homeostasis of the gut micro-biota by regulating the abundance,ultimately meliorate the function of intestinal mucosal barrier.
Toona sinensis bark alcohol extractulcerative colitisinflammatoryoxidative stressapopto-sisgut microbiota
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