RESUMO
ObjectiveTo 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）. MethodA total of 60 8-week-old NOD.H-2h4 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 （Real-time PCR） and Western blot， respectively. ResultCompared 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. ConclusionBuzhong 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.