In Type 1 diabetes, the body develops immune cells that target pancreatic beta cells, which play a critical role in the production and secretion of insulin. One of the earliest targets of this immune response is a specific sequence of amino acids, or peptide, within the insulin molecule, although what triggers this autoimmune response has to date been unknown.
Researchers at Joslin Diabetes Center and Boston College have now identified a species of human gut bacterium that makes a protein containing a sequence of amino acids that mimics the insulin peptide targeted by the immune system in Type 1 diabetes.
Analysis has revealed that the immune cells that target the insulin peptide in Type 1 diabetes cross-react with the similar sequence from the gut bacterial peptide, and that the presence of this bacterium can accelerate onset of Type 1 diabetes in a mouse model. Further investigation also revealed a link between the presence of the gut bacterium and the development of Type 1 diabetes in children at genetic risk of this disease.
“Although genetics and family history contribute to the risk of developing type 1 diabetes,” said C. Ronald Kahn, MD, Chief Academic Officer, Joslin Diabetes Center. “our findings demonstrate a new link in which there is molecular mimicry between a peptide made by normal gut microbes and the autoimmune response in Type 1 diabetes. This suggests the potential to develop new tools, including vaccines, antibiotics or probiotics, for the prevention and treatment of Type 1 diabetes and perhaps other autoimmune diseases.”
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