B-cell DNA damage response promotes islet inflammation in type 1 diabetes

Abstract

Type 1 diabetes (T1D) is an autoimmune disease where pancreatic b-cells are destroyed by islet-infiltrating T cells. Although a role for b-cell defects has been suspected, b-cell abnormalities are difficult to demonstrate. We show a b-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 b-cell DDR is more frequent in islets infiltrated by CD45+ immune cells, suggesting a link to islet inflammation. The b-cell toxin streptozotocin (STZ) elicits DDR in islets, both in vivo and ex vivo, and causes elevation of the proinflammatory molecules IL-1b and Cxcl10. b-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 b-cell DDR is an early event in T1D, possibly contributing to autoimmunity.