Composite Allografting for Promoting Survival of Corneal Transplants

描述(申请人提供)：角膜移植是角膜失明恢复视力的主要方式--全球第二大致盲原因。然而，超过50%的同种异体角膜移植放置在发炎(或高危)的移植床上，尽管最大限度地抑制了免疫功能，但仍失败了。在不复杂(或“低风险”)的移植物床上的移植成功率完全盖过了这一发生率，在局部类固醇的覆盖下，移植物床的失败率仅为10%。同种异体角膜移植物上皮在同种异体免疫中具有“矛盾”的特性：在作为功能屏障和结构性炎症调节/抑制因子的同时，它也承载着显著的同种异体抗原负荷。后一种特性导致宿主对移植物的同种异体抗原敏感，重要的是，这些同种异体抗原由移植物角膜内皮共享，而角膜内皮是排斥反应的关键靶点。因此，由同种异体吻合口-内皮细胞覆盖的异体第三方供体上皮组成的复合移植物很可能会使受体对第三方同种异体抗原敏感-移植物内皮不共享。因此，我假设这一策略将减少对移植物内皮的同种异体致敏作用，并在高危移植模型中提高移植物存活率。此外，这将提供上皮屏障功能，同时补充免疫调节因子，最大限度地促进同种异体移植物的存活。因此，这项研究的长期目标是使用这种复合移植物来促进移植物存活，这是与国家眼科研究所的任务相关的目标，也是临床领域高度可行的策略。在具体目标1中，我建议研究高危宿主中移植物上皮与基质内皮之间知之甚少的作用。这将通过在原位确定同种异体致敏作用以及通过开发体外测定同种异体致敏作用的方法在体内进行测试，并随后在体内环境中进行验证。在具体目标2中，我建议测试这种复合移植物是否能提高角膜移植的存活率。这将通过测量T细胞对移植物的渗透，通过过继转移试验评估效应性T细胞的体内功能，最后通过生物显微镜测量移植物的存活率来进行测试。外行描述：患有严重炎症的眼睛(所谓的“高危”宿主)的角膜移植成功率非常低。这些眼睛容易通过唤醒移植眼上被称为同种异体抗原的特定蛋白质而发生移植失败。在这项提案中，我将测试移植器官的重建以排除此类同种抗原是否会提高小鼠的移植存活率。C

DESCRIPTION (provided by applicant): Keratoplasty is the principal modality by which vision is restored in corneal blindness-the 2nd leading cause of blindness worldwide. Nevertheless, greater than 50% of corneal allografts placed in inflamed (or 'high-risk') graft beds fail despite maximal immune suppression. This incidence is completely overshadowed by the successful transplantation rates experienced in uncomplicated (or 'low-risk') graft beds, which boast a failure rate of only10% under cover of topical steroids. The epithelium of a corneal allograft has 'paradoxical' properties in alloimmunity: while it serves as a functional barrier and constitutive inflammation regulator/suppressor, it also carries a significant alloantigenic load. The latter property results in sensitization of the host against alloantigens of the graft, and importantly, these alloantigens are shared by the graft corneal endothelium-the critical target in rejection. It is therefore likely that composite grafts, consisting of allogeneic stoma-endothelium covered by an allodisparate 3rd-party donor epithelium, will sensitize the recipient to 3rd-party alloantigens-which are not shared by graft endothelium. I therefore hypothesize that this strategy will diminish allosensitization to graft endothelium and promote graft survival in a model of high-risk transplantation. Furthermore, this will provide epithelial barrier function along with the compliment of immunoregulatory factors to maximally promote allograft survival. Hence, the long-term objective of this study, which is to use such composite grafts to promote graft survival, is a goal relevant to the National Eye Institute mission and a highly feasible strategy in the clinical realm. In Specific Aim 1, I propose to examine the poorly understood roles of graft epithelium versus stroma- endothelium in high-risk hosts. This will be tested in vivo by identifying allosensitization in situ, as well as through the development of an in vitro assay to measure allosensitization, and subsequently verified in an in vivo setting. In Specific Aim 2, I propose to test whether such composite grafts promote corneal transplant survival. This will be tested by measuring T cell infiltration into the graft, assessing in vivo function of effector T cells via adoptive transfer assays, and finally the measurement of graft survival via biomicroscopy. LAY DESCRIPTION: Success rates for corneal transplantation are very poor in eyes with severe inflammation (so-called 'high-risk' hosts). These eyes are prone to graft failure by arousing certain proteins called 'alloantigens' on the transplant. In this proposal, I will test whether the reconstruction of transplants to exclude such alloantigens will promote transplant survival in mice. C