It is still unknown why people with rheumatoid arthritis develop an immune response to Subdoligranulum didolesgii. But we think it may be the culprit when it comes to rheumatoid arthritis because this bacteria is found only in the intestines of people with rheumatoid arthritis, and not in the intestines of healthy people.
While many immune responses happen in the intestines, they are usually self-contained and do not spread to other areas of the body. However, we believe that a particularly strong intestinal immune response against Subdoligranulum didolesgii could allow antibodies to bypass the intestinal “firewall” and spread to the joints.
Source: Rheumatoid arthritis: This gut bacteria could hold the key to a treatment