Targeting antigen to dendritic cells in autoimmune diabetes

在免疫正常的小鼠中，通过嵌合抗体构建物将蛋白质靶向DEC-205会导致抗原特异性的CD4+和CD8+T细胞的克隆性缺失或无能。在NOD小鼠中，一种自身免疫性糖尿病的小鼠模型，我们先前已经证明，抗DEC抗原治疗可以耗尽β细胞特异性CD8+T细胞(MukHopadhaya A等人)。PNAS 2008)。利用DEC-205靶向，我们现在已经确定在自身免疫性NOD小鼠中，CD8树突状细胞不能诱导CD4+T细胞耐受。相反，靶向DEC205+DC的同源抗原可诱导自身反应性CD4T细胞的扩增和干扰素-γ的产生。我们已经证明CD40/CD40L相互作用是在这种情况下很重要的途径之一：当给予抗CD40L特异性封闭抗体和抗DEC-205抗原时，T细胞反应更具耐受性(较少的增殖和干扰素γ的产生)。这项研究发表在今年的《白细胞生物学杂志》上。 CD11b+树突状细胞表面表达DCIR2，针对DCIR2的抗体可用于靶向该DC亚群。我们在NOD小鼠体内检测了抗DCIR2靶向BDC多肽刺激后BDC2.5 TCR转基因T细胞的反应。与DEC205+DC相比，DCIR2+DC能够诱导更多的耐受性反应，其特征是即使在这种慢性自身免疫的情况下，也能诱导更少的扩增、更多的凋亡和更少的干扰素-γ。此外，抗DCIR2靶向的BDC肽可抑制糖尿病的发生。通过比较DEC205+和DCIR2+树突状细胞在体内刺激后早期β细胞特异性T细胞的基因表达，我们已经确定了在DCIR2+树突状细胞刺激的T细胞中高水平表达的基因。

Targeting of proteins to DEC-205 through chimeric antibody constructs causes clonal deletion or anergy of antigen-specific CD4+ and CD8+ T cells in immunologically normal mice. In NOD mice, a mouse model for autoimmune diabetes, we previously have shown that beta cell-specific CD8+ T cells can be depleted by anti-DEC antigen treatment (Mukhopadhaya A, et al. PNAS 2008). Using DEC-205 targeting, we have now determined that in autoimmune NOD mice, CD8 DCs are not able to induce CD4+ T cell tolerance. Instead targeting cognate antigen to DEC205+ DCs induces expansion and IFN gamma production in the autoreactive CD4 T cells. We have shown that CD40/CD40L interactions are one pathway that is important in this setting: when a blocking antibody specific for anti-CD40L was given with anti-DEC-205 antigen, T cell responses were more tolerogenic (less expansion and IFN gamma production). This work was published this year in the Journal of Leukocyte Biology. CD11b+ dendritic cells express DCIR2 on their surface, and antibodies specific for DCIR2 can be used to target antigens to this DC subset. We have measured BDC2.5 TCR transgenic T cell responses in NOD mice after stimulation in vivo with anti-DCIR2-targeted BDC peptide. In contrast to the responses elicited by DEC205+ DCs, DCIR2+ DCs are able to induce a more tolerogenic response, characterized by less expansion, increased apoptosis and less IFN-gamma even in this chronic autoimmune context. In addition, anti-DCIR2-targeted BDC peptide inhibits diabetes development. By comparing gene expression in beta cell-specific T cells early after in vivo stimulation with either DEC205+ or DCIR2+ DCs, we have identified genes that are expressed at higher levels in T cells stimulated with DCIR2+ DCs.