During the onset of type 1 diabetes (T1D), the generation of pro-inflammatory signals may be required to facilitate T cell activation. We hypothesize that one of these signals is delivered by the ionotropic purinergic P2X7 receptor (P2X7R) on T cells, which senses extracellular ATP (eATP). Our central hypothesis is that eATP released by stressed, inflamed or damaged pancreatic islets engages P2X7R on T cells, thereby promoting Th1/Th17 cell generation and that the ATP/P2X7R axis may be a common pathway used by the various etiological factors thought to be involved in the onset of T1D in order to activate T cells. The primary goal of this application is to define the mechanisms whereby the ATP/P2X7R immunity promotes T1D and whether ATP/P2X7R targeting may halt T cells response in autoimmunity and prevents T1D onset. Our ultimate goal is to test a novel clinically relevant approach that we have developed and that, by quenching eATP, will prevent ATP/P2X7R immunity. Our preliminary data showed that pancreas/pancreatic islets greatly release eATP during hyperglycemia in a glucose dependent manner both in vitro and in vivo. eATP increased P2X7R expression on T cells in vitro and P2X7R-overexpressing T cells highly convert to Th1/Th17 cells. P2X7R is upregulated in islets infiltrating T cells in NOD mice and P2X7R targeting prevented Th1/Th17 differentiation, the autoimmune response in vitro, and disease onset in NOD mice. Individuals with new-onset T1D also showed increased peripheral P2X7R+T cells. In our experimental plan we will define the effects of ATP/P2X7R immunity and its blockade on T cell structure, function, cytotoxicity, adhesion and metabolism. We will also study whether treatment with a new therapeutic agent (sP2X7R) that quenches eATP, may prevent/delay the onset of T1D in vivo and abrogate immune response in human autoimmune relevant assays in vitro, thus establishing a novel therapeutic opportunity for T1D.