Tripterygium hypoglaucum (Levl.) Hutch extract ameliorates adjuvant-induced arthritis in mice by regulating gut microbiota

This study aimed to investigate the improvement of Tripterygium hypoglaucum (Levl.) Hutch (THH) extract on rheumatoid arthritis (RA) by regulating gut microbiota. The components of THH extract were identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). We proved that THH extract significantly alleviated the severity of RA symptoms like swollen ankle, joint cavity exudation, and articular cartilage destruction in adjuvant-induced arthritis (AIA) mice. Also, THH extract attenuated inflammatory responses in the joint of AIA mice by repressing the activation of TLR4 and p38 MAPK signaling pathway. Using 16S rDNA gene sequencing, gut microbiota dysbiosis was observed in AIA mice. For these changed intestinal bacteria, most of them were restored by THH extract at phylum, family, and genus levels, as indicated by the decreased abundances of pathogenic bacteria and the increased contents of beneficial bacteria. Meanwhile, the alterations of several metabolic pathways of gut microbiota in AIA mice were statistically reversed by THH extract. In addition, THH extract failed to prevent the occurrence of RA in AIA mice with intestinal flora depletion, consolidating the essential role of gut microbiota in THH extract-medicated protective effect on RA. In summary, THH extract can alleviate the development of RA in AIA mice by improving the dysbiosis of gut microbiota.