Mechanism of Buzhong Yiqi decoction (补中益气汤) for Hashimoto's thyroiditis: insights from gut microbiota and metabolomics

OBJECTIVE: To investigate the effect of Buzhong Yiqi decoction (补中益气汤BZYQ) and its potential mechanism by conducting a comprehensive analysis of intestinal microbiota and metabolomics in autoimmune thyroiditis (AIT) rats. METHODS: An AIT model with antibiotic cocktail were established. After 8 weeks of intervention with BZYQ, the levels of anti-thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TGAb) were measured. Pathological changes were assessed using hematoxylin and eosin staining. Changes of gut microbiota and fecal metabolites were analyzed through 16S RNA sequencing and metabolomics analysis. RESULTS: BZYQ intervention improved pathological damage of thyroid gland in AIT rats and significantly reduced the levels of anti-thyroid antibodies. Additionally, it had an ameliorative effect on the pathological damage of the colon. Also, BZYQ increased the abundance of Lactobacillus reuteri, reversing the dysbiosis of the gut microbiota. And BZYQ could regulate tryptophan metabolism of tryptophan to reverse metabolic disorders in HT. The correlation analysis indicated a close relationship between tryptophan metabolism and Lactobacillus reuteri. CONCLUSIONS: BZYQ is a promising therapeutic approach for HT. Its mechanism in treating HT may be associated with the regulation of gut microbiota dysbiosis and the improvement of gut-derived metabolic disorders.