Using dendritic cells to present beta cell antigens in vivo for manipulation of diabetes pathogenesis

为了寻找DC靶向胰岛素多肽改变糖尿病发病机制的条件，我们正在使用嵌合抗体，这种抗体可以靶向DCIR2+DC的几个来自胰腺β细胞自身抗原的多肽。之所以选择DCIR2+DC，是因为我们之前发表的数据表明，在NOD小鼠中，这一亚群比DEC205+DC更具耐受性。我们可以通过MHC II类I-Ag7四聚体染色跟踪抗原特异性T细胞，包括效应者和调节性细胞，并用适当的自体多肽在体内识别β细胞特异性CD4T细胞。我们现在正在测试同时给予抗原和IL-2如何改变NOD小鼠的抗原特异性效应T细胞和Foxp3+Tregs。低剂量的IL-2已经被证明可以选择性地增强Tregs，但抗原特异性细胞还没有得到明确的跟踪。虽然我们确实发现这种联合治疗增加了抗原特异性Tregs，但由于自身反应性效应器T细胞也可以表达高CD25，这些致病细胞也被扩增。在内源性抗原暴露的部位，即使没有添加DC靶向抗原，也可以观察到这种对自身抗原特异性Treg和TJeff的影响。由于目前使用IL-2治疗自身免疫的临床试验，这些结果是及时的，表明Foxp3+Tregs的外周扩张可能不是疾病治疗的良好生物标志物。

In order to find conditions in which DC-targeted insulin peptide can alter diabetes pathogenesis, we are using chimeric antibodies that can target several peptides derived from pancreatic beta cell self-antigens to DCIR2+ DCs. DCIR2+ DCs were chosen because of our previously published data showing this subset is more tolerogenic than DEC205+ DCs in NOD mice. We can follow antigen specific T cells, both effectors and regulatory cells using staining of MHC class II I-Ag7 tetramers with the appropriate self peptide for identifying beta cell-specific CD4 T cells in vivo. We are now testing how giving both antigen and IL-2 alters antigen-specific effector T cells and Foxp3+ Tregs in NOD mice. Low-dose IL-2 has been shown to selectively enhance Tregs, but antigen-specific cells have not been clearly followed. Although we do find that this combined treatment increases antigen-specific Tregs, because the autoreactive effector T cells can also express high CD25, these pathogenic cells are also expanded. In sites of endogenous antigen exposure, this effect on both auto-antigen specific Treg and Teff was observed even without addition of DC-targeted antigen. Because of current clinical trials using IL-2 to treat autoimmunity, these results are timely, and suggest that peripheral expansion of Foxp3+ Tregs may not be a good biomarker for disease treatment.