ß-Cell DNA Damage Response Promotes Islet Inflammation in Type 1 Diabetes.

Type 1 diabetes (T1D) is an autoimmune disease where pancreatic ß-cells are destroyed by islet-infiltrating T cells. Although a role for ß-cell defects has been suspected, ß-cell abnormalities are difficult to demonstrate. We show a ß-cell DNA damage response (DDR), presented by activation of the 53BP1 protein and accumulation of p53, in biopsy and autopsy material from patients with recently diagnosed T1D as well as a rat model of human T1D. The ß-cell DDR is more frequent in islets infiltrated by CD45+ immune cells, suggesting a link to islet inflammation. The ß-cell toxin streptozotocin (STZ) elicits DDR in islets, both in vivo and ex vivo, and causes elevation of the proinflammatory molecules IL-1ß and Cxcl10. ß-Cell-specific inactivation of the master DNA repair gene ataxia telangiectasia mutated (ATM) in STZ-treated mice decreases the expression of proinflammatory cytokines in islets and attenuates the development of hyperglycemia. Together, these data suggest that ß-cell DDR is an early event in T1D, possibly contributing to autoimmunity.