安石榴苷通过SIRT1/PGC-1α/NRF1通路对实验性结肠炎小鼠肠黏膜损伤的影响及其机制

Effects of punicalagin on intestinal mucosal injury in experimental colitis mice through SIRT1/PGC-1α/NRF1 pathway

目的从沉默信息调节因子1(SIRT1)/过氧化物酶体增殖物激活受体γ辅助激活因子-1α(PGC-1α)/核呼吸因子-1(NRF1)通路的角度探究安石榴苷(PUN)对实验性小鼠溃疡性结肠炎(UC)肠黏膜损伤的影响,并初步探究其作用机制。方法C57BL/6小鼠随机分为正常对照组、模型组、PUN低、高剂量组、SIRT1抑制剂组、PUN+SIRT1抑制剂组,每组12只。葡聚糖硫酸钠诱导建立实验性UC小鼠模型,观察小鼠UC症状并进行疾病活动指数评分;电镜观察结肠组织肠黏膜屏障结构损伤;HE染色及碘酸雪夫染色观察结肠组织病理损伤;ELISA法检测炎症因子如白细胞介素-12(IL-12)、白细胞介素-17(IL-17)及氧化应激产物-髓过氧化物酶(MPO)、细胞内活性氧(ROS)、丙二醛(MDA)水平;免疫组化染色观察SIRT1阳性表达;Western blot法检测SIRT1/PGC-1α/NRF1通路相关蛋白、抗氧化蛋白-超氧化物歧化酶2(SOD2)及谷胱甘肽S-转移酶(GST)、抗凋亡蛋白(Bcl2)、肠屏障结构相关蛋白(occludin、ZO-1)表达。结果与正常对照组相比,模型组UC疾病活动指数评分升高,小鼠肠黏膜屏障结构损伤、炎症浸润及杯状细胞损伤、凋亡等病理现象加重,炎症因子及氧化应激相关因子表达升高,SIRT1/PGC-1α/NRF1介导的抗氧化、抗凋亡途径激活(P<0.05)。与模型组相比,PUN低、高剂量均可进一步促进SIRT1/PGC-1α/NRF1介导的抗氧化、抗凋亡途径激活,改善小鼠肠黏膜屏障结构损伤、炎症浸润及杯状细胞损伤、凋亡等病理现象,降低UC小鼠疾病活动指数评分(P<0.05)。SIRT1抑制剂可逆转PUN的上述作用(P<0.05)。结论安石榴苷可通过激活SIRT1/PGC-1α/NRF1通路介导的抗炎、抗氧化、抗凋亡保护途径,改善实验性溃疡性结肠炎小鼠肠黏膜病理损伤程度。

This study was designed to explore the effect of punicalagin(PUN)on the intestinal mucosal damage of experimental ulcerative colitis(UC)mice by silent information regulator factor 2 related enzyme 1(SIRT1)/peroxisome proliferator-activated receptor gamma coactivator-1α(PGC-1α)/nuclear respiratory factor-1(NRF1)pathway,and to preliminarily explore its mechanism of action.C57BL/6 mice were randomly divided into normal control group,model group,PUN low-dose and high-dose groups,SIRT1 inhibitor group,PUN+SIRT1 inhibitor group,with 12 mice in each group.The experimental UC mouse model was induced by sodium dextran sulfate,and then the symptoms of UC in mice were observed and the disease activity index was scored;the damage of intestinal mucosal barrier structure in colon tissue was observed with electron microscope;the pathological damages such as inflammation and goblet cell metaplasia were observed by HE staining and iodate-Schiff staining;ELISA method was used to detect the levels of inflammatory factors interleukin-12(IL-12),interleukin-17(IL-17)and oxidative stress products-myeloperoxidase(MPO),intracellular reactive oxygen species(ROS)and malondialdehyde(MDA);the positive expression level of SIRT1 was observed by immunohistochemical staining;Western blot was used to detect the expression of SIRT1/PGC-1α/NRF1 pathway related proteins,antioxidant protein-superoxide dismutase 2(SOD2),glutathione S-transferase(GST),anti-apoptotic protein(Bcl2),intestinal barrier structure related protein(occludin,ZO-1).Compared with the normal control group,the UC disease activity index(UC-DAI)of the model group increased,the mouse intestinal mucosal barrier structure damage,inflammatory infiltration,goblet cell damage,apoptosis and other pathological phenomena aggravated,the expression of inflammatory factors and oxidative stress-related factors increased,and the antioxidant and anti-apoptotic pathways mediated by SIRT1/PGC-1α/NRF1 were activated(P<0.05).Compared with the model group,both low doses and high doses of PUN could further promote the activation of SIRT1/PGC-1α/NRF1-mediated anti-oxidation and antiapoptotic pathways,and alleviate mouse intestinal mucosal barrier structure damage,inflammatory infiltration and goblet cell damage,apoptosis and other pathological phenomena,and reduce UC-DAI in mice(P<0.05).All these effects of PUN mentioned above could be reversed by SIRT1 inhibitors(P<0.05).Taken together,PUN can activate the anti-inflammatory,anti-oxidant,and anti-apoptotic pathways mediated by the SIRT1/PGC-1α/NRF1 pathway,and alleviate the pathological symptoms of intestinal mucosal injury in experimental UC mice.