Chemokines and T Cell Recruitment in High Risk Corneal Allograft Rejection

描述（由主要研究者提供）：由于免疫排斥反应，“高风险”血管化角膜床受者的角膜异体移植存活率很低。我们的假设是，这些移植物与其他实体器官血管化异体移植物的命运相似，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细胞的协调募集和浸润介导的。最近，研究实体血管化器官异体移植的免疫排斥反应的研究表明，手术后移植部位早期诱导选择性趋化因子是T细胞进入排斥异体移植物的最佳招募所必需的。我们的数据表明，T细胞的募集进入移植物也是排斥的高风险血管化角膜异体移植物的关键。这与中性粒细胞趋化剂CXCL1/KC的早期产生和T细胞趋化剂CXCL9/Mig （IFN-3诱导的单因子）和CXCL10/IP10 （IFN-3诱导蛋白）的晚期上调有关。虽然体内中和CXCL1/KC可以提高移植物的存活率，但我们最近的数据显示，中和CXCL10/IP10会导致更快更强的排斥反应。在这个应用程序中，我们将测试高风险血管化角膜的行为与血管化实体器官移植的假设。CXCL1/KC的早期产生对于T细胞趋化剂的晚期诱导至关重要，而T细胞趋化剂是将同种异体特异性效应或调节性CD4 T细胞募集到移植物中所必需的。本应用中提出的实验的总体目标是了解血管化的角膜环境如何调节早期CXC趋化因子的产生，以及将启动的异体特异性效应和调节性T细胞募集到移植物中以介导排斥反应。在Aim 1中，我们将使用一种追踪抗原特异性T细胞的新系统进行测试，以监测同种异体特异性T细胞的启动，并测试这种情况是否被高风险的血管化角膜同种异体移植物改变，从而有更多具有不同表型的T细胞被优化用于募集。在Aim 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IFN-?的CXCR2+细胞的浸润来诱导T细胞趋化剂的晚期产生。Aim 3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细胞趋化剂是导致T细胞增加进入移植物的原因。我们还将利用荧光标记效应T细胞和调节性T细胞的新型动物模型来测试植入趋化因子如何改变它们的募集和移植物结果。本提案中描述的实验结果将为开发新的治疗试剂和策略确定目标，以抑制T细胞浸润到高风险的同种异体移植物中。这将最终提高移植物存活率，同时减少对目前可用的广泛性和衰弱性免疫抑制方案的依赖。严重角膜瘢痕导致失明的主要治疗方法是角膜移植。不幸的是，在角膜瘢痕与血管形成相关的患者中，移植的排异率很高。在本应用中提出的实验将研究如何通过趋化因子信号募集免疫细胞负责移植物排斥。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，以保持角膜移植清晰，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.