Novel Gut microbiota as new biomarkers to evaluate the therapeutic effect of different DMARDs in Rheumatoid Arthritis

Abstract Before and after the treatment of RA patients with DMARDs, how the interaction between abnormal intestinal flora and immune cells and cytokines is involved in the pathogenesis of RA remains unclear. Our study found that the α and β diversity of the gut microbiota did not change significantly in the untreated, csDMARDs and csDMARDs + bDMARD-treated RA patients. At the genus level, the relative abundance of Ruminococcaceae_Ruminococcus was decreased in the csDMARDs and csDMARDs + bDMARDs group, while the relative abundance of Faecalibacterium was reduced in the csDMARDs group compared to the untreated group. Ruminococcaceae_Ruminococcus was negatively correlated with Treg and pre-switched memory B cells, while positively correlated with effector memory Tfh and switched memory B cells in RA patients treated with DMARDs. Ruminococcaceae_Ruminococcus was positively interrelated with inflammatory cytokines such as IL-17A, IFN-γ, and TNF-α in RA patients receiving DMARDs. The disturbance of intestinal flora leads to the imbalance of immune cells and cytokines that are involved in the development of RA. Some intestinal flora might be used as novel biomarkers to evaluate the therapeutic effects of different DMARDs. These results provide theoretical support and experimental data for revealing the pathogenesis of RA and finding new targets for RA diagnosis and treatment.