Identification of Drug Targets and Potential Molecular Mechanisms of Wantong Jingu Tablet in Treatment of Rats with Collagen-Induced Arthritis based on 16S rDNA High-Throughput Sequencing and Metabolomic Analysis

Abstract Background: Wantong Jingu Tablet (WJT), a mixture of traditional Chinese medicine, can reduce the symptoms of rheumatoid arthritis (RA), but its pharmacological mechanism is unclear. The aims of this study were to investigate the therapeutic mechanisms of WJT for RA in vivo.Methods: The effects of WJT on the joint pathology, and the levels of Bax, Bcl-2,caspase-3, cleaved-caspase-3, ERK1/2, pERK1/2, TNF-α, IL-1β, and IL-6 were demonstrated based on several experiments in the model of collagen-induced arthritis (CIA) in rats. 16S rDNA high-throughput sequencing was used to investigate the effect of WJT on the overall structure and composition of gut microbiota. Meanwhile, metabolite changes in faeces were analyzed by metabolomics techniques. Results: The results showed that WJT restored the joint pathology in CIA rats, upregulated Bax and cleaved-caspase-3, downregulated Bcl-2, caspase-3, and pERK1/2, and reduced the levels of pro-inflammatory cytokines. The overall gut microbial structure in CIA rats was altered after WJT treatment. Three bacterial phyla were prominently restored: Bacteroidetes,Tenericutes and Deferribacteres, and three bacterial genera were significantly reversed: Vibrio, Macrococcus and Vagococcus. Furthermore, five specific metabolites associated with these specific bacterial genera were identified by correlation analysis. In addition, WJT supplement trended to down-regulate the other five metabolites according to metabolomic analyses. Conclusions: These results revealed that WJT restored the pathological changes of RA might through activating the mitochondrial apoptosis pathway, inhibited MEK/ERK signaling, and modulating the special bacteria and the special metabolites.