The Enemy Within: Gut Bacteria Drive Autoimmune Disease

Source: Yale University

Summary: According to a new study, Bacteria found in the small intestines of mice and humans can travel to other organs and trigger an autoimmune response.

Gut bacteria have been linked to a range of diseases, including autoimmune conditions characterized by immune system attack of healthy tissue. In an autoimmune disease, your immune system attacks healthy cells in your body by mistake. Researchers from the Yale University in a new study found that gut bacteria can travel to other organs and trigger an autoimmune response. They also found that the autoimmune reaction can be suppressed with an antibiotic or vaccine designed to target the bacteria. The team focused on Enterococcus gallinarum, a bacterium they discovered is able to spontaneously “translocate” outside of the gut to lymph nodes, the liver, and spleen. The study findings were published in the journal Science.

Gut bacteria drives autoimmune reaction

The gut bacterium E. gallinarum (blue) travels from the gut to the liver (and lymph nodes, not shown) to stimulate liver and immune cells that lead to inflammation and autoimmune reactions. Liver inflammation leads to autoimmune hepatitis. Autoantibodies generated systemically lead to lupus kidney disease and lupus-related autoimmune clotting called antiphospholipid syndrome. An oral antibiotic or a vaccine into the muscle that is directed against E. gallinarum prevent autoimmune diseases to occur. Credit: Martin Kriegel

In models of genetically susceptible mice, the team observed that in tissues outside the gut, E. gallinarum initiated the production of auto-antibodies and inflammation, hallmarks of the autoimmune response. They confirmed the same mechanism of inflammation in cultured liver cells of healthy people and the presence of this bacterium in livers of patients with autoimmune disease. When they blocked the pathway leading to inflammation, they could reverse the effect of this bug on autoimmunity. The vaccine against E. gallinarum was a specific approach, as vaccinations against other bacteria they investigated did not prevent mortality and autoimmunity. The vaccine was delivered through injection in muscle to avoid targeting other bacteria that reside in the gut. The findings suggest promising new approaches for treating chronic autoimmune conditions.

Senior author Martin Kriegel said, “The findings have relevance for systemic lupus and autoimmune liver disease”, “Treatment with an antibiotic and other approaches such as vaccination are promising ways to improve the lives of patients with autoimmune disease.”

More Information: S. Manfredo Vieira et al, “Translocation of a gut pathobiont drives autoimmunity in mice and humans,” Science (2018). … 1126/science.aar7201

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