Altered composition of gut microbiota in rheumatoid arthritis patients

Manifestation of rheumatoid arthritis (RA) can be attributed to both genetic and environmental factors. Some researchers have been focusing on intestinal microbiota which is thought to be one of the environmental factors that may enhance the development of RA. The advancement of culture-independent, high throughput microbial DNA sequencing had enabled us to understand the interplay between intestinal microbiota and host immune systems. In this study, we have reviewed the previous findings in animal and human studies with respect to the role of intestinal microbiota in RA. Mouse models of arthritis have demonstrated that gut microbiota plays a critical role in the disease development. K/BxN and IL-1 receptor-antagonist knock-out mice did not develop disease in germ free condition, however, colonization of particular intestinal bacteria was sufficient to induce arthritis. Moreover, the dysbiosis was observed in the human RA patients from United States, China and Finland. Thus, we believe that endeavors to improve the dysbiosis would serve as a novel therapeutic or preventive strategy in RA patients.