One major cause of human blindness is autoimmune uveitis, which is triggered by the activation of T cells, but exactly how and where the T cells become activated in the first place has been a long-standing mystery. A study, published as an open-access “Featured Article” in the August 18, 2015 issue of the journal Immunity, reveals that gut microbes produce a molecule that mimics a retinal protein, which most likely activates the T cells responsible for the disease. The article is titled “Microbiota-Dependent Activation of an Autoreactive T Cell Receptor Provokes Autoimmunity in an Immunologically Privileged Site." By shedding light on the cause of autoimmune uveitis in mice, the study could contribute to a better understanding of a broad range of autoimmune disorders and pave the way for novel prevention strategies in the future. "Given the huge variety of commensal bacteria, if they can mimic a retinal protein, it is conceivable that they could also mimic other self-proteins that are targets of inappropriate immune responses elsewhere in the body," says senior study author Dr. Rachel Caspi of the National Institutes of Health. "We believe that activation of immune cells by commensal bacteria may be a more common trigger of autoimmune diseases than is currently appreciated." Autoimmune uveitis, which accounts for up to 15% of severe visual handicap in the Western world, affects the working-age population and significantly affects public health. Patients often have detectable immune responses to unique retinal proteins involved in visual function, and these proteins can elicit the disease in animal models.Login Or Register To Read Full Story