基于Gal-3/NLRP3/IL-1β信号通路探讨异荭草苷治疗溃疡性结肠炎的作用机制

To Explore the Mechanism of Isoorientin in the Treatment of Ulcerative Colitis Based on Gal-3/NLRP3/IL-1βSignaling Pathway

目的探讨异荭草苷对葡聚糖硫酸钠(DSS)诱导的溃疡性结肠炎(UC)小鼠的治疗效果及其作用机制。方法将48只C57BL/6J小鼠随机分为正常组、模型组、美沙拉嗪组(600 mg·kg^(-1))、异荭草苷低剂量组(25 mg·kg^(-1))、异荭草苷高剂量组(50 mg·kg^(-1))及异荭草苷对照组(50 mg·kg^(-1)),每组8只。小鼠自由饮用2%DSS溶液复制UC模型,实验进行3周后,各给药组给予相应药物灌胃治疗4周。给药结束后,称取体质量,摘眼球取血,剖取结肠组织。采用苏木素-伊红(HE)、阿利新蓝-过碘酸-雪夫染色(AB-PAS)法观察小鼠结肠组织病理形态变化;透射电子显微镜观察小鼠结肠组织超微结构;酶联免疫吸附试验(ELISA)检测小鼠血清白细胞介素(IL)-6、IL-8、IL-10、IL-1β、肿瘤坏死因子α(TNF-α)、脂多糖(LPS)和髓过氧化物酶(MPO)水平;免疫组化法检测小鼠结肠组织中半乳糖凝集素(Gal-3)蛋白表达;免疫荧光法检测黏蛋白(MUC2)表达及NOD样受体热蛋白结构域相关蛋白3(NLRP3)和凋亡相关斑点样蛋白(ASC)共定位情况;免疫印迹(Western Blot)法检测小鼠结肠组织中Gal-3、NLRP3、ASC、半胱氨酸蛋白酶1(Caspase-1)、IL-1β、IL-18、闭合蛋白(Occludin)、闭锁小带蛋白1(ZO-1)蛋白表达。结果与正常组比较,模型组小鼠体质量明显下降,结肠长度明显缩短,肠质量指数明显增加(P<0.01);小鼠肠黏膜结构紊乱,微绒毛稀疏,隐窝结构见大量炎性细胞浸润,线粒体肿胀明显,杯状细胞明显减少;血清IL-6、IL-8、IL-1β、TNF-α、LPS和MPO水平明显升高,IL-10水平明显降低(P<0.01);结肠组织MUC2蛋白阳性表达减少及NLRP3和ASC共定位增强;结肠组织中Gal-3、NLRP3、ASC、Caspase-1、IL-1β和IL-18蛋白表达明显增加,Occludin和ZO-1蛋白表达明显降低(P<0.01)。与模型组比较,异荭草苷低、高剂量组小鼠体质量明显上升,结肠长度明显增长,肠质量指数明显降低(P<0.05,P<0.01);肠黏膜、微绒毛及线粒体结构明显恢复,炎性浸润减轻,杯状细胞明显增加;血清IL-6、IL-8、IL-1β、TNF-α、LPS和MPO水平明显降低,IL-10水平明显升高(P<0.05,P<0.01);结肠组织MUC2蛋白阳性表达增加,NLRP3和ASC共定位减弱;结肠组织中Gal-3、NLRP3、ASC、Caspase-1、IL-1β和IL-18蛋白表达明显降低,Occludin和ZO-1蛋白表达明显增加(P<0.05,P<0.01)。结论异荭草苷对DSS诱导的UC小鼠具有良好的治疗效果,其机制可能与抑制Gal-3/NLRP3/IL-1β信号通路,保护肠黏膜屏障有关。

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 factorα(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-1βsignaling pathway.