Graft-specific factors promoting intestinal rejection

描述（由申请人提供）：肠道移植的结果不如其他器官移植，主要是由于肠道同种异体移植物具有更大的免疫原性，以及需要大量免疫抑制以防止排斥反应而产生的并发症。这些事实强调需要了解肠道同种异体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过程中起着重要作用。我们假设肠同种异体移植物内的肠系膜淋巴结（MLN）和Peyer’s patches （PP）是唯一且有效地启动同种异体反应性T细胞的部位。由于受体T细胞在肠道淋巴器官中被激活，因此受体T细胞表达转运分子，有利于它们随后迁移到肠上皮，在那里它们介导排斥反应。具体目的1是确定受体同种异体T细胞的启动是否可以在供体MLN和PP中发生，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的突变小鼠（LTalpha-/-和aly/aly）将被用作肠道同种异体移植的受体和/或供体。T细胞在供体和受体淋巴器官中的启动将通过Elispot和细胞内细胞因子染色进行评估。特异性目的2是确定趋化因子（CCR6和CCR9）和整合素（CD103和alpha4beta7）是否在环境和微生物抗原反应下调节肠道T细胞运输，也调节受体T细胞响应肠道异体抗原的运输。这些分子在T细胞运输到肠道同种异体移植物中的作用将使用敲除小鼠和针对每种分子的特异性单克隆抗体进行检测。每个分子的作用将通过活体显微镜，In（111）标记细胞的积累，以及从肠移植物的各个隔室分离的T细胞的流式细胞术分析来量化。具体目标3是将阻断目标1和目标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，试图设计出更特异性和更有效地预防肠道同种异体移植物排斥反应的方案。

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.