Graft-specific factors promoting intestinal rejection

描述(申请人提供)：肠移植的结果不如其他移植器官，主要是因为同种异体肠移植的免疫原性更强，以及防止排斥所需的大量免疫抑制所产生的并发症。这些事实强调了需要了解导致同种异体肠道移植排斥反应的独特机制，并利用这些知识来设计更有效的免疫抑制。对其他移植器官的研究表明，受体次级淋巴器官在排斥反应过程中起着重要作用。我们假设同种异体小肠移植物中的肠系膜淋巴结(MLN)和Peyer‘s斑块(PP)是唯一和有效地激活同种异体反应性T细胞的部位。由于受体T细胞已经在肠道的淋巴器官中被激活，所以它们表达的运输分子有利于它们随后迁移到肠道上皮细胞，在那里它们介导排斥反应。具体目的1是确定供体MLN和PP中是否可以发生受体同种异体反应性T细胞的启动，如果可以，相对于受体淋巴器官中更传统的T细胞启动过程，这一过程对肠道排斥反应的贡献。在这些实验中，缺乏所有淋巴结和PP(LTalpha-/-和Aly/Aly)的突变小鼠将被用作同种异体肠道移植的受体和/或供体。通过ELISPOT和细胞内细胞因子染色来评估供者和受者淋巴器官中T细胞的激活情况。具体目的2是确定已知调节肠道T细胞运输的趋化因子(CCR6和CCR9)和整合素(CD103和α4beta7)是否也调节受体T细胞对肠道同种异体抗原的运输。这些分子在T细胞转运到同种异体肠道移植物中的作用将通过基因敲除小鼠和针对每个分子的单抗来检验。每种分子的作用将通过活体显微镜、In(111)标记细胞的积累和从移植肠不同部分分离的T细胞的流式细胞术分析来量化。具体目标3是将阻断AIMS 1和AIMS 2中重要步骤的药物与其他小分子或生物免疫抑制剂结合起来，试图设计更特异和有效地防止同种异体肠道移植排斥反应的方案。

DESCRIPTION (provided by applicant): Results of intestinal transplantation are inferior to other transplanted organs primarily due to the greater immunogenicity of intestinal allografts and complications arising from the large amount of immunosuppression required to prevent rejection. These facts underscore the need to understand the unique mechanisms responsible for intestinal allograft rejection and to use this knowledge to design more effective immunosuppression. Studies of other transplanted organs demonstrate an important role for recipient secondary lymphoid organs in the rejection process. We hypothesize that mesenteric lymph nodes (MLN) and Peyer's patches (PP) within intestinal allografts serve as sites that uniquely and efficiently prime alloreactive T cells. By virtue of having been primed in the lymphoid organs of the intestine, recipient T cells express trafficking molecules that favor their subsequent migration to the intestinal epithelium where they mediate rejection. Specific aim 1 is to determine whether priming of recipient alloreactive T cells can occur in donor MLN and PP and if so, the contribution this process to intestinal rejection relative to the more conventional process of T cell priming in recipient lymphoid organs. For these experiments mutant mice that lack all lymph nodes and PP (LTalpha-/- and aly/aly) will be used as recipients and/or donors for intestinal allografts. T cell priming in donor and recipient lymphoid organs will be assessed by Elispot and intracellular cytokine staining. Specific aim 2 is to determine whether chemokines (CCR6 and CCR9) and integrins (CD103 and alpha4beta7) known to regulate intestinal T cell trafficking in response to environmental and microbial antigens also regulate the trafficking of recipient T cells in response to intestinal alloantigens. The role of these molecules in T cell trafficking to intestinal allografts will be examined using knockout mice and monoclonal antibodies specific for each molecule. The effects of each molecule will be quantified using intravital microscopy, accumulation of In(111) labeled cells, and flow cytometric analysis of T cells isolated from the various compartments of intestinal grafts. Specific aim 3 is to combine agents that block those steps shown to be important in aims 1 and 2 with other small molecule or biologic immunosuppressant agents in a attempt to design regimens that more specifically and effectively prevent the rejection of intestinal allografts.