AURORA, Colo., Feb. 12 (UPI) -- Scientists have identified a hybrid insulin peptide as the possible trigger for the autoimmune response causing type 1 diabetes, according to a new study with mice.
University of Colorado researchers made the finding while working to understand why immune cells attack the body's own tissues, finding a mutation causing the formation of the hybrid peptides.
Type 1 diabetes is an inherited autoimmune disorder, which involves insulin-producing beta cells in the pancreas to be destroyed by immune cells.
"Our lab studies the type of T cell known as a CD4 T cell," said Dr. Kathryn Haskins, a professor of immunology and microbiology at the University of Colorado School of Medicine, in a press release. "We have focused on autoreactive CD4 T cells using a mouse model of autoimmune diabetes. We have been especially interested in identifying the antigens that activate these T cells."
The researchers first worked with mice, using mass spectrometry, to find the peptide targets of CD4 T cells in type 1 diabetes.
They found a new class of antigen present in beta cells consisting of insulin fragments fused to peptides of other proteins, which leads to the generation of hybrid insulin peptides not encoded in an individual's genome. The mutation no longer matching the proper gene is then identified as a foreign body, causing the autoimmune response.
Researchers write in the study, published in the journal Science, that similar hybrid peptides were found in T cells isolated from the pancreatic islets of two people with type 1 diabetes as well. This, they said, suggests future research into their possible role in driving the disease.