Microbiology

More Than a Gut Feeling

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Science  06 Aug 2010:
Vol. 329, Issue 5992, pp. 610-611
DOI: 10.1126/science.329.5992.610-c

Shortly after birth, the human gut is colonized by 1000 microbial species, which eventually number hundreds of trillions of cells in an adult, far exceeding the total number of our own cells. Microbes colonize the gut to gain access to a rich food source, and in return they are known to improve human health by enhancing our digestive system and providing extra defenses against pathogens. However, they can also negatively affect the host immune response, and they have been linked to the development of autoimmune diseases, particularly those of the gut such as inflammatory bowel disease. To investigate how gut microbes can cause the development of an autoimmune disease elsewhere, Wu et al. used mice engineered to develop inflammatory arthritis. These mice were reared under germ-free conditions, thereby inhibiting microbial colonization of the gut, which was found to delay the onset of arthritis and to reduce its severity. Initiation of autoimmune arthritis in this model is driven by the adaptive immune response. Consistent with this, the authors found reduced T helper 17 (TH17) cell capabilities in the germ-free mice. TH17 cells can cause autoimmune disease, and gut microbes can induce the production of these cells in the intestine. The authors show that a single commensal gut microbe introduced in the germ-free mice promoted the differentiation of TH17 cells and triggered arthritis, thereby linking a distal autoimmune disease to the gut microbiota.

Immunity 32, 815 (2010).

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