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[摘要]：OBJECTIVE-Immunotherapy using peptides from the beta-cell antigen GAD65 can preserve glucose homeostasis in diabetes-prone NOD mice; however, the precise mechanisms that arrest islet-reactive T cells remain unresolved. Our previous work revealed that a dominant GAD65 epitope contained two overlapping I-A(g7)-restricted determinants, 524-538 and 530-543, with the former associated with amelioration of hyperglycemia. Here, we sought to discover whether p524-538-specific T cells could directly regulate islet-reactive T cells. RESEARCH DESIGN AND METHODS-Prediabetic NOD mice were used to determine the relationship between peptide p524-538-induced interleukin (IL)-13 and regulation of islet autoimmunity. Pancreatic lymph node (PLN) cells from mice at distinct stages of islet inflammation, peri-insulitis versus invasive insulitis, were harvested to establish the expression pattern of IL-13 receptor alpha 1 (IL-13R alpha 1) on islet-associated T cells. RESULTS-Peptide p524-538 preferentially induced IL-13-producing T cells that antagonized the release of gamma-interferon by spontaneously arising GAD65 autoinununity, and recombinant human IL-13 inhibited proliferation of islet-reactive clonotypic T cells. A subset of CD4(+) T cells in NOD and NOD.BDC2.5 T cell receptor transgenic mice expressed functional IL-13R alpha 1, which induced phosphorylation of signal transducer and activator of transcription 6 in the presence of cognate cytokine. Notably, the number of IL-13R alpha 1(+) T cells was heightened in the PLN of young NOD mice when compared with older female counterparts with advanced insulitis. Immunization with p524-538 preserved IL-13R alpha 1 expression on PLN T cells. CONCLUSIONS-IL-13 may be important for regulating autoimmunity in the early stages of insulitis, and the loss of IL-13R alpha 1 on islet-reactive T cells may be a biomarker for fading regional immune regulation and progression to overt diabetes. Diabetes 60:1716-1725, 2011 |
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