雷公藤多苷通过抑制 TLR4/NF-κB信号通路抑制小鼠结肠炎症

摘要

背景：临床实践中，雷公藤多苷对溃疡性结肠炎（UC）具有良好的疗效，但确切机制不明。目的：探讨雷公藤多苷对葡聚糖硫酸钠（DSS）诱导的小鼠结肠炎模型的治疗作用及其可能机制。方法：60只健康雄性 BALB/ c 小鼠随机分为6组：模型对照组、低、中、高剂量雷公藤多苷组、空白对照组和正常对照组，前四组自由饮用5% DSS 溶液1周复制结肠炎模型，同时予蒸馏水或相应浓度雷公藤多苷[9.01、27.03、81.09 mg/（ kg·d）]灌胃，持续3周。观察各组动物结肠黏膜组织病理学改变，采用 RT-PCR 和蛋白质印迹法检测 TLR4 mRNA 和蛋白表达，免疫组化染色检测 NF-κB p65表达，ELISA 法检测 IL-1α、TNF-α、IL-13含量。结果：雷公藤多苷组小鼠结肠黏膜出现不同程度的组织损伤和炎症改变，但均轻于模型对照组。各组雷公藤多苷组结肠黏膜组织 TLR4 mRNA 和蛋白表达、NF-κB p65表达和组织匀浆上清中的 IL-1α、TNF-α含量均显著低于模型对照组（P <0.01），中、高剂量组间差异无统计学意义（P >0.05，除 TNF-α），均显著低于低剂量组（P <0.05），但仍高于空白对照组和正常对照组（ P <0.05）。结论：雷公藤多苷对 DSS 小鼠结肠炎有良好的保护作用，其可能通过抑制 TLR4/ NF-κB 信号通路激活及其下游促炎细胞因子表达、分泌而抑制结肠炎症反应。%Background:Tripterygium glycosides(TG)is effective for treatment of ulcerative colitis(UC)in clinical practice, however,the underlying mechanism has not been clarified yet. Aims:To investigate the therapeutic effect of TG on dextran sulfate sodium(DSS)-induced experimental colitis in mice and its possible mechanisms. Methods:Sixty healthy male BALB/ c mice were randomly divided into six groups:model control group,low,medium and high-dose TG group,blank control group and normal control group. Mice in the first four groups drank 5% DSS freely for 7 days to induce experimental colitis;simultaneously,distilled water,9. 01,27. 03 or 81. 09 mg/(kg·d)TG were given intragastrically for 21 days in these four groups,respectively. Histopathological changes of colonic mucosal tissues were observed;expressions of TLR4 mRNA and protein were determined by RT-PCR and Western blotting;expression of NF-κB p65 was detected by immunohistochemistry;concentrations of IL-1α,TNF-α and IL-13 were measured by ELISA. Results:Tissue damage and inflammation in varying degrees were observed in colonic mucosal tissues in TG groups with different dosage,but all were less severe than those in model control group. Expressions of TLR4 mRNA,TLR4 protein,and NF-κB p65 in colonic mucosal tissues,as well as concentrations of IL-1α and TNF-α in supernatant of colonic homogenate were significantly lower in TG groups than those in model control group(P < 0. 01). These parameters in medium and high-dose TG groups were significantly lower than those in low-dose TG group(P < 0. 05),but higher than those in blank control group and normal control group(P < 0. 05). Except for TNF-α,no significant differences were seen between medium and high-dose TG groups(P > 0. 05). Conclusions:TG exerts a protective effect on DSS-induced experimental colitis in mice. The underlying mechanism of its anti-inflammatory effect might be related with the inhibition of TLR4 / NF-κB signaling pathway activation and subsequently suppressing downstream proinflammatory cytokines expression and secretion.