Local Expression of TNFα in Neonatal NOD Mice Promotes Diabetes by Enhancing Presentation of Islet Antigens

Abstract

The relationship of inflammation to autoimmunity has been long observed, but the underlying mechanisms are unclear. Here, we demonstrate that islet-specific expression of TNFα in neonatal nonobese diabetic mice accelerated diabetes. In neonatal transgenic mice, disease was preceded by apoptosis of some β cells, upregulation of MHC class I molecules on residual islet cells, and influx and activation of both antigen-presenting cells bearing MHC–islet peptide complexes and T cells. Infiltrating dendritic cells/macrophages, but not B cells, from neonatal islets activated islet-specific T cells in vitro. Thus, inflammation can trigger autoimmunity by recruiting and activating dendritic cells/macrophages to present self-antigens to autoreactive T cells.