A new animal model signifying a decisive bridge between innate immunity and the pathognomonic morphological characteristics of Type 1 Diabetes

Available animal models for Type 1 Diabetes (T1D) show limited similarities with the human disease and have no predictive value in screening for effective intervention therapies. Heat-inactivated bacteria instilled in the ductal compartment of the pancreas in healthy rats rapidly cause periductal inflammation and accumulation of mainly granulocytes and monocytes in the exocrine pancreas and in the peri-islet area mimicking the acute pancreatic inflammation in subjects with recent onset T1D. After three weeks, the triggered exocrine inflammation had vanished and pancreases showed normal morphology. However, a distinct accumulation of both CD4+ and CD8+ T cells within and adjacent to affected islets was found in one third of the rats, mimicking the pathognomonic insulitis in T1D. As in human T1D, the insulitis affected a fraction of all islets and was observed only in certain lobes of the pancreases. The presented animal model for T1D will allow detailed mechanistic studies to unravel a previously unknown interplay between bacteria-activated innate immunity and an acquired cellular immunity forming the immunopathological events described in humans at different stages of T1D. Summary StatementThe results presented signify a previously unknown decisive bridge between innate immunity and formation of the pathognomonic immunopathological events described in subjects with recent onset T1D.