Remote control — triggering of brain autoimmune disease in the gut

•Multiple sclerosis is triggered by a combination of genetic and environmental factors.•Growing evidence in mouse models implicates intestinal microbiota in triggering CNS autoimmune disease.•Intestine provides milieu for T cell differentiation.•Dietary substances contribute to immune functions and regulate autoimmunity.

Converging evidence indicates that multiple sclerosis, an inflammatory demyelinating disease of the central nervous system, is caused by brain-specific, self-reactive T lymphocytes. These are normal components embedded in the human immune system throughout healthy life. Only upon activation in the periphery, the T cells assume properties that enable them to break through the vascular blood–brain barrier and to invade the brain white matter. While activation has been traditionally associated with microbial infections, recently, studies of animal models revealed a critical role of the commensal gut flora as a key triggering factor. These findings may pave the way to new strategies to treat MS and other human autoimmune diseases, and commend a reevaluation of dietary approaches.