Exosomes and Donor Antigen Cross-dressing in Pancreatic Islet Transplantation

项目总结/摘要 胰岛移植的最终目标是达到长期植入的耐受性， 维持免疫抑制一些研究表明，某些细胞外囊泡（外来体）发挥作用， 在涉及同种异体移植的排斥和耐受的免疫应答中起重要作用。 最近，我们报道了小鼠胰岛移植后，许多受体细胞占据供体细胞， 囊泡并在其表面上呈递同种异体MHC分子（allo-MHC交叉敷料）;这一过程导致 体内同种异体反应性T细胞的活化。此外，胰腺分泌胰岛素的β 已知细胞通过自身抗原和RNA的转移促进炎症和糖尿病。 总之，这表明外泌体可能在胰岛同种异体移植物的排斥反应中起关键作用。支持这一 鉴于此，我们已经获得了初步证据，即用2种试剂体内阻断供体外泌体的产生， GW 4869和cambinol抑制小鼠同种异体MHC交叉敷料并延长心脏移植物存活 (up 80天）。与这一建议最相关的是，我们获得的初步数据表明， 体外同种异体胰岛（注射前）与这些GW 4869抑制供体MHC交叉敷料， 在这些胰岛的小鼠受体中消除同种异体反应性T细胞的活化。 与它们在排斥反应中的作用相反，外泌体也被证明可以促进免疫耐受。为 例如，来源于FoxP 3+调节性T细胞的外泌体（Treg-外泌体）抑制炎症，并且可以 介导啮齿动物中自身和同种异体抗原的免疫耐受。另一方面，据我们所知， 由调节性B细胞产生的外泌体（Breg-外泌体）的致耐受性从未被研究过。 我们的目标是：1）研究参与供体外泌体释放的细胞和抗原的性质 和胰岛移植后的交叉敷料，2）测试胰岛移植物的长期存活是否可以 通过抑制供体外泌体产生和/或MHC交叉修饰或通过受体 施用致耐受性外来体。 目标1.研究供体抗原交叉修饰受体细胞的机制， 胰岛移植 目标二。抑制胰岛移植小鼠中供体外泌体释放和交叉敷料 目标3：使用来自调节细胞的外泌体实现胰岛移植物的长期存活 我们预计，我们的提案将1）为启动 胰岛移植后同种免疫和排斥反应过程，2）为设计 在胰岛移植和潜在的自身免疫和其他免疫性疾病中的新的基于外泌体的耐受方案 炎性免疫紊乱

PROJECT SUMMARY / ABSTRACT The ultimate goal of islet transplantation is to achieve tolerance defined as long-tem engraftment without maintenance immunosuppression. Several studies suggest that certain extracellular vesicles (exosomes) play an essential role in the immune responses involved in both rejection and tolerance of allogeneic transplants. Recently, we reported that, after pancreatic islet transplantation in mice, many recipient cells, take up donor vesicles and present allogeneic MHC molecules on their surface (allo-MHC cross-dressing); a process leading to activation of alloreactive T cells in vivo. In addition, exosomes released by pancreatic insulin-secreting beta cells are known to promote inflammation and diabetes through transfer of auto-antigens and RNA. Altogether, this suggests that exosomes might play a key role in the rejection of islet allografts. Supporting this view, we have obtained preliminary evidence that in vivo blocking of donor exosome production with 2 agents, GW4869 and cambinol, inhibited allo-MHC cross-dressing and prolonged survival of heart allografts in mice (up to 80 days). Most relevant to this proposal, we have obtained preliminary data showing that treatment of allogeneic islets in vitro (pre-injection) with these GW4869 suppressed donor MHC cross-dressing and nearly abrogated activation of alloreactive T cells in mice recipient of these islets. Contrasting with their role in rejection, exosomes have also been shown to promote immune tolerance. For instance, exosomes derived from FoxP3+ regulatory T cells (Treg-exosomes) suppress inflammation and can mediate immune tolerance of auto- and allo-antigens in rodents. On the other hand, to our knowledge, the tolerogenicity of exosomes produced by regulatory B cells (Breg-exosomes) has never been investigated. Our objectives are: 1) to investigate the nature of the cells and antigens involved in donor exosome release and cross-dressing after islet transplantation and, 2) test whether long-term islet allograft survival could be achieved through inhibition of donor exosome production and/or MHC cross-dressing or via recipient administration with tolerogenic exosomes. Aim 1. Investigate the mechanisms involved in donor antigen cross-dressing of recipient cells after islet transplantation Aim 2. Inhibit donor exosome release and cross-dressing in islet-transplanted mice Aim 3. Achieve long-term islet allograft survival using exosomes derived from regulatory cells We anticipate that our proposal will 1) bring new insights into the mechanisms underlying the initiation of alloimmunity and rejection process after pancreatic islet transplantation and, 2) set the path for the design of novel exosome-based tolerance protocols in islet transplantation and potentially autoimmune and other inflammatory immunological disorders.