Award Number : W 81 XWH - 07 - 1 - 0121 TITLE : Humanized in vivo Model for Autoimmune Diabetes PRINCIPAL INVESTIGATOR

A human T-cell receptor (TcR) derived from an autoreactive T-cell specific for GAD65, from a subject at high risk for autoimmune diabetes, was introduced into HLA-DR4 transgenic mice. The source of TcR was a CD4þ TH1 þ T-cell clone which responded to an immunodominant epitope of the human islet protein GAD65, an epitope shared with both GAD65 and GAD67 in the mouse. The resulting HLA-DR4/GAD-TcR transgenic mice on a Rag2/I-Ab/B6 background exhibited a CD4þ infiltrate into pancreatic islets that correlated with a loss of insulin in infiltrated islets. These mice also exhibited a subclinical impaired tolerance to exogenously fed glucose as assayed by an intraperitoneal glucose tolerance test. T cells containing the GAD65/67 (555e567) responsive TcR undergo strong negative selection as evidenced by a 10-fold lower thymocyte cellularity compared to non-TcR transgenic mice, and clonotype peripheral T cells represented approximately 1% of CD4þ T cells in Rag2 sufficient mice. Upon in vitro stimulation, GAD65/67 555e567 responsive T cells secrete interferon-g, minimal interleukin (IL)-2 and tumor necrosis factor-a, and no IL-4, IL-5, IL-10, or IL-17, consistent with a TH1 profile. These data demonstrate that CD4 þ T cells specific for a naturally processed epitope within GAD can specifically home to pancreatic islets and lead to impaired islet b-cell function in diabetesassociated HLA-DR4 transgenic mice on the relatively non-autoimmune C57BL/6 background. The relatively slow progression and patchy insulitis are reminiscent of the chronic pre-clinical phase similar to a majority of human at-risk subjects, and models these indolent features of human T1D. 2007 Elsevier Ltd. All rights reserved.