Intestinal allograft tolerance in large animals

项目摘要：尽管最近在免疫抑制方面有所改善，但移植物/患者的小肠存活率 移植(ITX)仍然是次优的，限制了该疗法的广泛应用。授权人的诱因- 对任何器官的特异性耐受性是消除与免疫抑制相关的共病的理想方法 治疗。诱导耐受性对于ITX是特别可取的，因为：(1)对高水平的要求 免疫抑制以预防小肠移植的排斥反应；(2)与重型 免疫抑制；(3)受者的年轻平均年龄。然而，据我们所知，容忍 在临床前模型中，同种异体肠移植尚未得到广泛的研究。即使在啮齿动物模型中，也很少有 报告显示对小肠有耐受性，但一种成功的策略是通过诱导 持久的混合同种异体嵌合体。这项提案的总体目标是开发一种大型动物临床前阶段 ITX后耐性诱导模型及亲本耐受性诱导方案的研究 给儿童(活体捐赠者)ITX。我们最近报告说，临床受者的排斥率似乎更高。 离体肠移植(IITx)与包括供体肝脏的多脏器移植(MVTx)相比， 胃和胰腺。值得注意的是，我们首次发现了T细胞的混合嵌合体 IITx之后没有GVHD，甚至更常见的是MVTx之后没有GVHD，与减少排斥反应有关 费率。我们假设在这些MVTx受体中存在移植物抗宿主反应性(GVHR)克隆 促进包含在移植物中的供体祖细胞的植入，并进一步假设 在GVHR期间移植额外的造血干细胞(HSCs)将增加 即使在iITx受体中也存在嵌合体和耐受诱导。移植物向移植物迁移的早期移植物抗宿主病 受者的外周免疫系统(淋巴造血性GVH反应，或LGVHR)使造血 植入这些造血祖细胞的“空间”。在这项提案中，我们将利用MHC近亲繁殖 小型猪，唯一的大型动物模型，允许定义GVH和GVH可重复移植 宿主对移植物(HVG)的遗传障碍，以解决上述假设并开发临床相关的LD ITX 耐受诱导模型。我们将首先建立一个猪的原位iITx和MvTx模型，与我们的 机构的临床方案，并确定GVH和HVG同种反应性在推动嵌合体和 临床结果(目标1)。然后我们将利用LGVHR和捐赠者的HSCs来实现长期的耐受 AIM 1(AIM 2)模型中的同种异体移植受体。这项建议中的研究可能最终具有临床意义 适用性，可以解决ITX中最有问题的问题，并极大地改善这一结果 治疗方式。

Project Abstract: Despite recent improvements in immunosuppression, graft/patient survival of small intestinal transplantation (ITx) remains suboptimal, limiting the broader application of this therapy. Induction of donor- specific tolerance to any organ is desirable to eliminate co-morbidities associated with immunosuppressive treatment. The induction of tolerance is particularly desirable for ITx due to: (1) the requirement for high levels of immunosuppression to prevent rejection of small bowel grafts; (2) complications associated with heavy immunosuppression; and (3) the young average age of the recipients. However, to our knowledge, tolerance of intestinal allografts has not been extensively studied in preclinical models. Even in rodent models, there are few reports demonstrating tolerance to small intestine, but one successful strategy has been through the induction of durable mixed allogeneic chimerism. The overall goal of this proposal is to develop a large animal preclinical model for tolerance induction following ITx and to develop a protocol appropriate for tolerance induction in parent to child (living donor LD) ITx. We recently reported that rejection rates appear to be higher in clinical recipients of isolated intestinal transplants (iITx) compared to multivisceral transplants (MVTx), which include donor liver, stomach and pancreas. Notably we have found, for the first time, that T cell mixed chimerism which develops without GVHD following iITx and even more commonly following MVTx, is associated with reduced rejection rates. We hypothesize that the presence of graft-vs-host-reactive (GVHR) clones in these MVTx recipients facilitates engraftment of donor progenitor cells contained within the grafts, and further hypothesize that transplantation of additional hematopoietic stem cells (HSCs) during this period of the GVHR will augment chimerism and tolerance induction even in iITx recipients. The early GVHR that migrates from the graft to the recipient’s peripheral immune system (lymphohematopoietic GVH response, or LGVHR) makes hematopoietic “space” for engraftment of these hematopoietic progenitors. In this proposal, we will utilize MHC inbred miniature swine, the only large animal model that allows reproducible transplantation with defined GVH and host-vs-graft (HvG) genetic barriers, to address the above hypotheses and develop a clinically relevant LD ITx tolerance induction model. We will first establish a porcine model of orthotopic iITx and MvTx that parallels our institution’s clinical protocol and determine the role of GVH and HvG alloreactivity in driving chimerism and clinical outcomes (Aim 1). We will then utilize the LGVHR and donor HSCs to achieve tolerance in long-term allograft acceptors in the models in Aim 1 (Aim 2). The studies in this proposal may have eventual clinical applicability that could solve the most problematic issues in ITx and vastly improve the outcomes of this therapeutic modality.