Doctors may have been looking in the wrong place for understanding how rheumatoid arthritis develops - new research suggests it starts from bacteria in the gut. Although medicine knows that rheumatoid arthritis is an auto-immune disease, researchers at Harvard Medical School have discovered that the process is kick-started by bacteria in the gut. As all of us have the bacteria, it seems there are several more elements to the development of the disease. For a start, a person suffering from arthritis is more susceptible to the bugs, and it could be because of genetic or environmental factors, or both. The susceptible person's body produces more of a subset of T cells that the immune system reacts to, triggering the arthritis. (Source: Immunity, 2010; doi: 10.1016/j.immuni.2010.06.001).