补中益气汤对AIT小鼠Th17/Treg免疫失衡及Notch1信号通路的影响

Effect of Buzhong Yiqitang on Th17/Treg Immune Imbalance and Notch1 Signaling Pathway in AIT Mice

目的:探讨补中益气汤对自身免疫性甲状腺炎(AIT)小鼠辅助性T细胞17(Th17)/调节性T细胞(Treg)免疫失衡及果蝇双翅边缘缺刻同源基因1(Notch1)信号通路的影响。方法:将60只8周龄NOD.H-2^(h4)小鼠,随机分为正常组、模型组、西药组(硒酵母片,32.5 mg·kg^(-1))、补中益气汤低、中、高剂量组(4.78、9.56、19 g·kg^(-1)),每组10只。正常组饲以蒸馏水,其余各组饲以含0.05%碘化钠水8周,自发形成AIT动物模型后,依据分组灌胃给药8周麻醉处死小鼠。酶联免疫吸附测定法(ELISA)检测血清抗甲状腺球蛋白抗体(TGAb)、促甲状腺激素(TSH)、游离三碘甲状腺原氨酸(FT3)、游离甲状腺激素(FT4)含量;苏木素-伊红(HE)染色法观察甲状腺组织改变;实时荧光定量聚合酶链式反应(Real-time PCR)和蛋白免疫印迹法(Western blot)分别检测甲状腺组织维甲酸相关孤核受体γt(RORγt)、白细胞介素(IL)-17、叉头样转录因子3(FoxP3)、IL-10、Notch1、发状分裂相关增强子1(Hes1)mRNA及蛋白表达水平。结果:与正常组比较,模型组小鼠甲状腺结构破坏严重,淋巴细胞明显浸润,血清TGAb、FT3及FT4含量显著升高,TSH含量显著降低(P<0.01),RORγt、IL-17、Notch1、Hes1 mRNA及蛋白表达水平明显升高,FoxP3、IL-10 mRNA及蛋白表达水平显著降低(P<0.01);与模型组比较,各给药组小鼠甲状腺结构破坏及淋巴细胞浸润程度有所改善,血清TGAb、FT3及FT4含量显著降低,TSH含量升高,RORγt、IL-17、Notch1、Hes1 mRNA及蛋白表达水平均有不同程度降低,FoxP3、IL-10 mRNA及蛋白表达水平均有不同程度升高(P<0.05,P<0.01),以补中益气汤中剂量组干预效果最为显著。结论:补中益气汤可缓解AIT小鼠甲状腺结构损伤,其机制可能与改善Th17/Treg免疫细胞异常分化,抑制Notch1信号通路激活有关。

Objective:To explore the effect of Buzhong Yiqitang on the immune imbalance of helper T cell 17(Th17)/regulatory T cell(Treg)and Notch1 signaling pathway in mice with autoimmune thyroiditis(AIT).Method:A total of 608-week-old NOD.H-2^(h4) mice were randomly divided into the normal group,model group,western medicine group(selenium yeast tablet,32.5 mg·kg^(-1)),and low-dose(4.78 g·kg^(-1)·d^(-1)),middle-dose(9.56 g·kg^(-1)·d^(-1)),and high-dose(19 g·kg^(-1)·d^(-1))Buzhong Yiqitang groups,with 10 mice in each group.The normal group was fed with distilled water,and the other groups were fed with water containing 0.05%sodium iodide for eight weeks.After the animal model of AIT was formed spontaneously,the mice were killed under anesthesia after intragastric administration for eight weeks.Serum anti-thyroglobulin antibodies(TGAb),thyroid-stimulating hormone(TSH),free triiodothyronine(FT3),and free thyroid hormone(FT4)were detected by enzyme-linked immunosorbent assay(ELISA),and thyroid tissue changes were observed by hematoxylin-eosin(HE)staining.The mRNA and protein expressions of retinoid-related orphan receptor-γt(RORγt),interleukin(IL)-17,forkhead box P3(FoxP3),IL-10,Notch1,and hair division-related enhancer 1(Hes1)in thyroid tissue were detected by Real-time fluorescence quantitative polymerase chain reaction(Realtime PCR)and Western blot,respectively.Result:Compared with the normal group,the thyroid structure of the model group was severely damaged,and lymphocytes were infiltrated obviously.The levels of serum TGAb,FT3,and FT4 contents were significantly increased,and TSH content was significantly decreased(P<0.01).The mRNA and protein expression levels of RORγt,IL-17,Notch1,and Hes1 were significantly increased,while those of FoxP3 and IL10 were significantly decreased in the model group(P<0.01).Compared with the model group,thyroid structural damage and lymphocyte infiltration were improved in the treatment groups,and serum TGAb,FT3,and FT4 contents were significantly decreased.TSH content was increased,and mRNA and protein expression levels of RORγt,IL-17,Notch1,and Hes1 were decreased.mRNA and protein expression levels of FoxP3 and IL-10 were increased to different degrees(P<0.05,P<0.01),and the middle-dose Buzhong Yiqitang group had the most significant intervention effect.Conclusion:Buzhong Yiqitang can alleviate the thyroid structural damage in AIT mice,and its mechanism may be related to improving the abnormal differentiation of Th17/Treg immune cells and inhibiting the activation of the Notch1 signaling pathway.