Rheumatoid arthritis (RA) is a prevalent systemic autoimmune disease, caused by a combination of genetic and environmental factors. Here we performed 16S sequencing on 30 samples from rheumatoid arthritis patients and controls. We identified the presence of Prevotella copri as strongly correlated with disease in new-onset untreated rheumatoid arthritis (NORA) patients. Increases in Prevotella abundance correlated with a reduction in Bacteroides and a loss of reportedly beneficial microbes in NORA subjects. We also identified unique Prevotella genes that correlated with disease. Prognosis of RA may be predicted based on the presence of some clinical and laboratory evidences. New criteria for classification of RA provide opportunity for earlier treatment. Initiation of treatment particularly by combination of DMARDs concurrent with short duration of corticosteroid is expected to prevent progressive course and even change the natural course of RA. At present any patients with clinical synovitis in at least one joint may have definite RA, requiring agressive treatment.

Keywords: Rheumatoid arthritis, NORA, Prevotella and P.copri