"Many autoimmune arthritis researchers are less focused on the stealthy bacteria of a leaky gut than on the community of gut microbes as a whole. Their work is an outgrowth of the Human Microbiome Project, a National Institutes of Health initiative to catalog all the microbes in our system. What’s already clear is that changes in our bacterial populations are associated with changes in our health. In a still-unpublished study, Dr. Scher and his team identified a particular microbe that was common in a large cohort of rheumatoid-arthritis patients but was much less prevalent in the healthy group. In two related studies, researchers discovered a microbe that can activate an immune response; in germ-free mice that were genetically predisposed to autoimmune arthritis, it was enough to cause the disease."
The Boy With a Thorn in His Joints - NYTimes.com