To Explore the Mechanism of Isoorientin in the Treatment of Ulcerative Colitis Based on Gal-3/NLRP3/IL-1β Signaling Pathway
Objective To investigate the therapeutic effect of isoorientin on ulcerative colitis(UC)mice induced by dextran sulfate sodium(DSS)and its mechanism.Methods Forty-eight C57BL/6J mice were randomly divided into control group,model group,mesalazine group(600 mg·kg-1),isoorientin low dose group(25 mg·kg-1),isoorientin high dose group(50 mg·kg-1)and isoorientin control group(50 mg·kg-1),with eight mice in each group.Mice were free to drink 2%DSS solution to replicate UC model.After three weeks of experiment,each drug administration group was given corresponding drug by intragastric administration for four weeks.After the last administration,the body weight was weighed,blood was taken from eyeballs,and colon tissue was dissected.The pathological changes of colon were observed by hematoxylin-eosin(HE)and alcian blue-periodic acid-Schiff(AB-PAS)staining.The ultrastructure of colon tissue was observed by transmission electron microscope.Serum levels of interleukin(IL)-6,IL-8,IL-10,IL-1β,tumor necrosis factor α(TNF-α),lipopolysaccharide(LPS)and myeloperoxidase(MPO)were detected by enzyme-linked immunosorbent assay(ELISA).The expression of galectin-3(Gal-3)protein in colon tissue of mice was detected by immunohistochemistry analysis.The expression of MUC2 and the co-localization of NOD-like receptor heat protein domain associated protein 3(NLRP3)and apoptosis-associated speck-like protein(ASC)were detected by immunofluorescence assay.The protein expression of Gal-3,NLRP3,ASC,Caspase-1,IL-1β,IL-18,Occludin,and zonula occludens protein-1(ZO-1)in colon tissue of mice were detected by Western Blot.Results Compared with the control group,the body weight and colon length in the model group were shortened significantly,while the index of colonic weight of mice were increased significantly(P＜0.01).The intestinal mucosal structure of mice was disordered,the microvilli were sparse,the crypt structure was infiltrated by a large number of inflammatory cells,mitochondria were significantly swollen,and goblet cells were obviously decreased.Serum levels of IL-6,IL-8,IL-1β,TNF-α,LPS,and MPO were significantly increased,while IL-10 level was significantly decreased(P＜0.01).The positive expression of MUC2 protein in colon tissue was decreased and the co-localization of NLRP3 and ASC was enhanced.The protein expression of Gal-3,NLRP3,ASC,Caspase-1,IL-1β,and IL-18 in colon tissue were significantly increased,and the protein expression of Occludin and ZO-1 were significantly decreased(P＜0.01).Compared with the model group,the body weight and colon length of mice in isoorientin low-and high-dose groups were significantly increased,the index of colonic weight of mice was apparently decreased(P＜0.05,P＜0.01).The structure of intestinal mucosa,microvilli and mitochondria recovered obviously,inflammatory infiltration was alleviated,and goblet cells were increased obviously.Serum levels of IL-6,IL-8,IL-1β,TNF-α,LPS,and MPO were significantly decreased,while IL-10 level was significantly increased(P＜0.05,P＜0.01).The positive expression of MUC2 protein in colon tissue was increased and the co-localization of NLRP3 and ASC was reduced.The protein expression of Gal-3,NLRP3,ASC,Caspase-1,IL-1β,and IL-18 in colon tissue were significantly decreased,and the protein expression of Occludin and ZO-1 were significantly increased(P＜0.05,P＜0.01).Conclusion Isoorientin has a great therapeutic effect on DSS-induced UC mice.Its mechanism may be related to the protection of intestinal mucosal barrier by Gal-3/NLRP3/IL-1β signaling pathway.
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