Chemokines and T Cell Recruitment in High Risk Corneal Allograft Rejection

描述(由主要研究人员提供)：由于免疫排斥反应，“高危”血管化角膜床受体的角膜移植物存活率很低。我们的假设是，这些移植物的命运类似于其他实体器官血管化同种异体移植物的命运，这些移植物需要积极的全身免疫抑制来提高存活率。同种异体移植物的排斥反应是通过同种异体特异性T细胞的协调募集和渗透来实现的。最近，对实体血管同种异体器官移植免疫排斥反应的研究表明，术后早期在移植部位诱导选择性趋化因子是T细胞最佳募集到排斥移植物中所必需的。我们的数据显示，T细胞在移植物中的募集也是高危带血管同种异体角膜移植排斥反应的关键。这与中性粒细胞趋化因子CXCL1/KC的早期产生和T细胞趋化因子CXCL9/Mig(由干扰素-3诱导的单核细胞因子)和CXCL10/IP10(干扰素-3诱导的蛋白)的晚期上调有关。虽然体内中和CXCL1/KC导致移植物存活率增加，但我们最近的数据表明，CXCL10/IP10的中和导致更快和更强的排斥反应。在这项应用中，我们将检验这样一种假设，即高危血管化角膜的行为类似于血管化实体器官移植。CXCL1/KC的早期产生对T细胞趋化因子的后期诱导至关重要，T细胞趋化因子是同种异体特异性效应T细胞或调节性CD4T细胞重新进入移植物所必需的。本申请中提出的实验的总体目标是了解带血管的角膜环境如何调节早期CXC趋化因子的产生，以及启动的同种异体特异性效应细胞和调节性T细胞招募到移植物中以介导排斥反应。在目标1中，我们将使用一种新的跟踪抗原特异性T细胞的系统进行测试，以监测异体特异性T细胞的启动情况，并测试高危血管同种异体角膜移植对这种变化的影响，以使更多具有不同表型的T细胞优化招募。在目标2中，我们将确定CXCL1/KC的细胞来源，并测试CXCL1/KC如何通过增加产生干扰素的CXCR2+细胞的渗透来诱导T细胞趋化物质的晚期产生。目标3中的实验将使用中和抗体和缺乏CXCL/9/Mig的小鼠来测试这种T细胞趋化物质是导致T细胞增加到移植物中的原因。我们还将利用带有荧光标记的效应T细胞和调节性T细胞的新型动物模型来测试移植物内趋化因子如何改变它们的招募和移植物结果。这项建议中描述的实验结果将确定开发新的治疗试剂和抑制T细胞渗透到高危移植物中的策略的目标。这最终将提高移植物的存活率，同时减少对现有的全身性和衰弱的免疫抑制方案的依赖。公共卫生相关性严重的角膜瘢痕所致失明的主要治疗方法是角膜移植。不幸的是，在角膜疤痕与血管形成相关的患者中，移植的排斥率很高。这项申请中提出的实验将检验趋化因子信号对免疫细胞的招募如何与移植排斥反应有关。我们相信，这些趋化因子的局部中和将是一种新的治疗形式，可以保持角膜移植的清晰度，并改善血管化瘢痕角膜患者的视力结果。

DESCRIPTION (provided by principal investigator): The survival rate of corneal allografts in "high risk" vascularized corneal bed recipients is poor due to immune rejection. Our hypothesis is that these grafts are similar to the fate of other solid organ vascularized allogeneic grafts that require aggressive systemic immune-suppression to improve survival. The rejection of allografts is mediated through the coordinated recruitment and infiltration of allo-specific T cells. Most recently, studies investigating the immunological rejection of solid vascularized organ allotransplants have shown that the early induction of selective chemokines at the site of transplantation after surgery is required for the optimal recruitment of T cells into rejecting allografts. Our data shows that recruitment of T cells into the graft is also critical in rejection of high risk vascularized corneal allografts. This correlates to the early production of the neutrophil chemoattractant CXCL1/KC and late up-regulation of the T cell chemoattractants: CXCL9/Mig (monokine induced by IFN-3) and CXCL10/IP10 (IFN-3-inducible protein). Although the in vivo neutralization of CXCL1/KC results in increased graft survival, our recent data shows that neutralization of CXCL10/IP10 causes a faster and robust rejection. In this application we will test the hypothesis that a high risk vascularized cornea behaves like a vascularized solid organ transplant. The early production of CXCL1/KC is crucial to the late induction of T cell chemoattractants necessary for the recruitment of allo-specific effector or regulatory CD4 T cells into the graft. The overall goal of the experiments proposed in this application is to understand how the vascularized corneal environment regulates early CXC chemokine production and the recruitment of primed allo-specific effector and regulatory T cells into the graft to mediate rejection reactions. In Aim 1, we will test using a novel system of tracking antigen specific T cells, to monitor allo-specific T cells priming and test this is altered by high risk vascularized corneal allografts in such a way that there are more T cells with a different phenotype optimized for recruitment. In Aim 2, we will identify the cell source of CXCL1/KC and test how CXCL1/KC induces the late production of T cell chemoattractants by increasing infiltration of CXCR2+ cells that produce IFN-?. Experiments in Aim 3 will use neutralizing antibodies and mice deficient in CXCL/9/Mig to test that this T cell chemoattractant is responsible for the increased recruitment of T cells into the graft. We will also utilize novel animal models with fluorescently labeled effector and regulatory T cells to test how intragraft chemokines alter their recruitment and graft outcome. The results from experiments described in this proposal will identify targets for the development of novel therapeutic reagents and strategies to inhibit T cell infiltration into high risk allografts. This will ultimately improve graft survival while decreasing the dependence on the generalized and debilitating immunosuppressive regimens currently available. PUBLIC HEALTH RELEVANCE The main treatment for blindness caused by severe corneal scarring is corneal transplantation. Unfortunately, in patients where corneal scarring is associated with blood vessel formation, the rejection rate of the transplant is high. The experiments proposed in this application will examine how the recruitment of immune cells by chemokine signals is responsible for graft rejection. We believe that the local neutralization of these chemokines will be a novel form of therapy to keep corneal transplants clear and improve the visual outcome in patients with vascularized scarred corneas.