Genetic Modification of Mouse Islets for Transplantation

描述（由申请人提供）：胰岛移植治疗I型糖尿病（T1DM）的成功取决于其控制T细胞介导的同种异体反应和¿-细胞自身免疫的能力。诱导共刺激物(ICOS)/ b7相关蛋白1（B7RP-1）信号传导对Th1和Th2细胞功能的调控至关重要。用ICOS拮抗剂治疗可抑制Th1和Th2介导的炎症、EAE、过敏性气道疾病和粘膜炎症性疾病，并保护异体心脏移植物免受免疫排斥。我们假设，对胰岛进行基因修饰，使其局部表达可溶性ICOS-Ig，可以保护胰岛移植物免受免疫排斥。这种保护的机制可能涉及通过促进效应T细胞的凋亡和/或能量而使其失活。我们将使用重组腺相关病毒（rAAV）将ICOS-Ig或其他控制基因传递到胰岛细胞。AAV是一种非致病性病毒，免疫原性很小，因此在临床应用中可能是安全的。最近的研究表明，通过rAAV转导对胰岛进行遗传修饰可导致报告基因在体内的长期表达，而不干扰胰岛素的产生。最后，局部表达ICOS-Ig可能不影响全身免疫功能，为延长移植胰岛存活提供了一种安全的手段。因此，基于表达ICOS-Ig的胰岛移植抑制效应T细胞的免疫治疗可能对维持同基因和异体胰岛移植物耐受性特别有效。在本应用中，我们将：1)优化表达共刺激抑制剂ICOS-Ig的转基因小鼠胰岛的生成条件；2).观察表达同基因和异体胰岛的ICOS-Ig移植是否能预防糖尿病复发；3)确定ICOS-Ig在移植胰岛功能维持中的作用。

DESCRIPTION (provided by applicant): The success of islet transplantation therapy for Type I diabetes mellitus (T1DM) depends on its ability to control both T cell-mediated alloreactivity and the ¿-cell autoimmunity. Inducible costimulator (ICOS)/B7-related protein 1(B7RP-1) signaling is crucial for regulation of effector Th1 and Th2 cell function. Treatment with ICOS antagonist inhibits Th1 and Th2 mediated inflammation, EAE, allergic airway disease, and mucosal inflammatory disease, and protects allogeneic heart grafts from immunorejection. We hypothesize that genetic modification of the islets to locally express soluble ICOS-Ig may protect the islet-grafts from immunorejection. The mechanism(s) underlying this protection may involve the inactivation of effector T cells by promoting their apoptosis and/or anergy. We will use recombinant adeno-associated virus (rAAV) to deliver the ICOS-Ig or other control genes to the islet cells. AAV is a non-pathogenic virus and has little immunogenicity, may therefore be safe in clinical applications. Recent studies have demonstrated that genetic modification of the islets by rAAV transduction results in the long-term expression of reporter genes in vivo, which does not interfere with insulin production. Finally, the local expression of ICOS-Ig may not affect systemic immunological function, providing a safe means to prolong transplanted islet survival. Therefore, immunotherapy based on transplantation with ICOS-Ig expressing islets to inhibit effector T cells may be especially effective for maintaining syngeneic and allogeneic islet-graft tolerance.In this application, we will: 1). optimize conditions for generation of genetically modified mouse islets which express costimulation inhibitor ICOS-Ig; 2). examine whether transplantation of ICOS-Ig expressing syngeneic and allogeneic islets prevents the recurrence of diabetes; and 3). determine the action of ICOS-Ig in the functional maintenance of transplanted islets. These studies will address fundamental questions concerning the regulatory function of ICOS/B7RP-1 signaling on alloreactive and autoimmune T cell responses. Our findings may provide the basis for novel immunotherapies for the prevention and inhibition of immunorejection of islet grafts in man.