甘草酸苷调节内质网应激PERK-elF2α-NF-κB信号通路治疗溃疡性结肠炎的机制研究

Study on the mechanism of glycyrrhizin regulating PERK-elF2 alpha-NF-kappa B signaling pathway of endoplasmic reticulum stress to treat ulcerative colitis

目的从PERK-elF2α-NF-κB信号通路角度研究甘草酸苷(GL)对溃疡性结肠炎(UC)小鼠结肠炎症的治疗作用和可能机制。方法BALB/c小鼠90只,随机分为6组:正常对照组、模型对照组、阳性对照组和GL低、中、高剂量组。通过右旋葡聚糖硫酸钠(DSS)法制备UC模型,GL低、中、高剂量组造模同时予GL灌胃10d。观察小鼠的一般状态、结肠大体形态和组织病理特点;运用ELISA酶联法检测结肠中TNF-α、IL-1β、IL-6、IL-17和IL-10的水平;分别运用免疫组织化学SP法和荧光定量PCR法检测结肠中GRP78、PERK、elF2α和NF-κB蛋白和mRNA的表达水平。结果与模型小鼠相比,GL各剂量组小鼠的临床症状、结肠大体损伤和组织病理损伤均减轻,GL高剂量组的DAI、CMDI和TDI均显著降低(P<0.01),GL中、高剂量组的TNF-α、IL-1β、IL-6、IL-17水平均明显降低(P<0.01),IL-10的含量明显升高(P<0.01),上述通路蛋白的表达及其mRNA水平均降低(P<0.05)。结论GL能有效治疗UC小鼠的结肠炎症,其作用机制可能与抑制PERK-eIF2α-NF-κB信号通路活化、减轻IECs炎症损伤有关。

Objective To investigate the therapeutic effect of glycyrrhizin(GL)on colon inflammation in ulcerative colitis(UC)mice and its possible mechanism from the perspective of PERK-elF2α-NF-κB signaling pathway.Methods Ninety BALB/c mice were divided into six groups randomly as follows:normal control group,model control group,salazosulfapyridine(SASP)/positive control group,low-dose GL group,middle-dose GL group and high-dose GL group.UC model was established by dextran sulphate sodium(DSS),and daily GL gavage administration was given for ten days at the same time in GL groups.The general state,gross morphology and histopathological characteristics of colon of mice were observed;TNF-α,IL-1β,IL-6,IL-17 and IL-10 were determined by ELISA;the expressions level of GRP78,PERK,elF2 alpha and NF-kappa B protein and mRNA in colon tissues were detected by immunohistochemical SP method and fluorescence quantitative PCR respectively.Re⁃sults Compared with UC mice,the clinical symptoms,colon gross injury and histopathological injury of GL groups were all re⁃duced;DAI,CMDI and TDI of high-dose GL group were all greatly declined(P<0.01);the contents of TNF-α,IL-1β,IL-6,IL-17of medium-and high-dose GL group were all significantly descended(P<0.01);the content of IL-10 was dis⁃tinctly ascended(P<0.01);and the protein and mRNA levels of those pathway proteins were all decreased(P<0.05).Con⁃clusion The therapeutic effect of GL on colon inflammation of UC is efficient,the mechanism may be related to its inhibition of activation of PERK-elF2α-NF-κB signaling pathway,and the reduction of IECs inflammatory injury.