Antigen-specific tolerance in T1 diabetes by IDO loaded functionalized dendrimers

描述（由申请人提供）：抗原特异性耐受的诱导被认为是治疗T1 D的圣杯，无论是在发病后早期还是在胰岛移植后。尽管T1 D自身抗原的列表远未完成，并且仍然不知道T1 D自身抗原是什么。 其中一个（如果有的话）是最“重要”的一个，越来越多的证据表明，胰岛素是NOD小鼠和人类1型糖尿病中致病性T细胞的关键靶点，它甚至可能是这种疾病中长期寻求的“起始抗原”。鉴于树突状细胞（DC）在建立外周T细胞耐受中的重要作用，基于DC的策略正在被探索为促进耐受的重要途径。事实上，对胎儿-母体和肿瘤诱导的耐受性的理解的进展突出了表达吲哚胺-2，3双加氧酶（IDO）的致耐受性DC在该过程中发挥的关键作用。此外，DC的体外转染显示IDO足以诱导致耐受性表型。目前基于DC的方案旨在诱导耐受性，需要在体外制备和转染自体DC，然后再输注到患者体内。因此，手术的成本和技术挑战似乎是压倒性的，需要高度专业化的中心。为了克服这一限制，我们提出使用一种新的纳米结构基因为基础的疫苗输送，有效地和特异性靶向抗原呈递细胞（APC）。因此，我们的策略是基于选择性靶向DC以使用我们的纳米平台在体内共同递送作为DNA的疾病相关自身抗原以及IDO。我们预期，在靶向DNA转染后，DC同时表达胰岛素和IDO将诱导耐受性应答，这将减轻/停止胰岛的自身免疫破坏。该平台基于与MHC II类结合肽共价缀合的聚酰胺胺（PAMAM）树状聚合物（作为DNA加载表面），所述MHC II类结合肽充当靶向APC（特别是DC）的配体。该平台将在NOD小鼠中进行测试，评估：1）其在过继转移的胰岛素特异性T细胞中诱导耐受性的能力和2）其在预防糖尿病或糖尿病发作时的治疗功效。所提出的用于体内靶向基因递送的肽-树枝状聚合物平台应产生与传统的APC制备方法相同（或甚至更高）的致耐受性功效，具有相当大的优点，包括：i）低成本（一剂肽-树枝状聚合物估计花费1美元），和ii）制备和施用简单，减少了对专门中心的需要。此外，通过使用INS B 9-B29靶向肽，其不仅以高亲和力结合IAg 7 MHC II类分子，而且结合人HLA DQ 8分子，该平台开启了将阳性结果容易地转化为临床的现实可能性。

DESCRIPTION (provided by applicant): Induction of antigen-specific tolerance is perceived as the Holy Grail for the treatment of T1D, either early after onset or following islet transplantatio. Although the list of auto-antigens in T1D is far from being complete, and it is still unknown which one (if any) is the most "important" one, accumulating evidence suggests that insulin is a key target of pathogenic T cells in type 1 diabetes in both NOD mice and humans, and that it may even be the long-sought-after 'initiating antigen' in this disease. Given the important role of dendritic cells (DCs) in the establishment of peripheral T cell tolerance, DC-based strategies are being explored as an important route to promote tolerance. In fact, advancements in the understanding of fetal-maternal and of tumor-induced tolerance highlight the key role that tolerogenic DC expressing Indoleamine-2,3 Dioxygenase (IDO) play in this process. Moreover, in vitro transfection of DC shows that IDO is sufficient to induce a tolerogenic phenotype. Current DC-based protocols aimed at the induction of tolerance require the in vitro preparation and transfection of autologous DC before reinfusion into patients. As such, the cost and technical challenges of the procedure appear overwhelming and require highly specialized centers. To overcome this limit, we propose the use of a novel nanostructure gene-based vaccine delivery that efficiently and specifically targets antigen-presenting cells (APC). Our strategy is therefore based on the selective targeting of DCs to co-deliver, as DNA, a disease-relevant autoantigen together with IDO in vivo using our nano-platform. We expect that, following targeted DNA transfection, the simultaneous expression of insulin and IDO by DC will induce a tolerogenic response that will mitigate/halt autoimmune destruction of islets. This platform is based on polyamidoamine (PAMAM) dendrimer (as a DNA loading surface) covalently conjugated to an MHC class II binding peptide that acts as a ligand to target APC, in particular DCs. The platform will be tested in NOD mice by evaluating: 1) its capacity to induce tolerance in adoptively transferred insulin-specific T cells and 2) its therapeutic efficacy in prevention of or at diabetes onset. The proposed peptide-dendrimer platform for in vivo targeted gene delivery should result in the same (or even a higher) tolerogenic efficacy seen with traditional methods for APC preparation, with sizable advantages including: i) low cost (one dose of peptide-dendrimer is estimated to cost 1$), and ii) simplicity in preparation and administration reducing the need for specialized center. Moreover, by using the INS B9-B29 targeting peptide that binds with high affinity not only the IAg7 MHC class II molecule, but also the human HLA DQ8 molecule, this platform opens the realistic possibility of an easy translation of positive findings towards the clinic.