虹膜-睫状体-房水：角膜移植排斥防治的新途径及其机制研究

There are above 3 million blind people waiting for corneal transplantation to recover the sight. However, postoperative rejection is still the most important reason that causes the failure of transplantation. Classical theory cannot explain the corneal endothelium-type rejection, and conventional clinical anti-rejection therapy seems ineffective to prolong donor corneal survival periods. Our study has found that the iris-ciliary body-aqueous humor shows numerous immune cell infiltration during corneal graft rejection. Moreover, the implantation of immunosuppressive drug-delivery system in the anterior chamber seems to be more effective than conventional treatments to control the corneal transplantation rejection. These findings suggest that the intraocular “iris-ciliary body-aqueous humor" may represent another important pathway that mediates immune rejection of corneal transplantation. However, the corneal endothelial antigen recognition and the initiating mechanism of immune rejection in the intraocular pathway remained unclear. Therefore, in the present study, we will explore the mechanisms of corneal endothelial antigen recognition and immune rejection initiation, the influence of anterior chamber microenvironment change on the c-Rel/mTOR activity and function of Treg cells. The aim of this project is to clarify the function of "iris-ciliary body-aqueous humor" pathway in the rejection reaction of corneal transplantation, and the targets of anterior chamber-implanted sustained releasing immunosuppressive drugs for preventing the corneal graft rejection. The results will be helpful for the development and clinical application of new drug forms for the prevention of corneal transplantation rejection.

我国有300万角膜盲人需行角膜移植复明，术后免疫排斥是失败的最重要原因。经典的“角膜缘免疫排斥途径”理论难以解释临床常见的内皮型排斥现象，且防治效果不佳。我们研究发现：角膜移植排斥发生时，眼内虹膜-睫状体-房水中出现大量免疫细胞，眼前房植入免疫抑制缓释药物能有效防治排斥反应。由此提出，“虹膜-睫状体-房水途径”可能是造成角膜移植免疫排斥的另一重要通路，但供体角膜内皮细胞抗原在该通路中如何被识别并启动免疫排斥发生的机理仍不清楚。因此，本课题拟对眼前房中抗原递呈细胞识别异体角膜内皮抗原、启动免疫排斥反应的信号机制，以及眼前房免疫微环境变化对虹膜-睫状体中Treg细胞c-Rel/mTOR活性和免疫抑制功能的影响进行研究，旨在阐明“虹膜-睫状体-房水途径”在角膜移植免疫排斥过程中的作用及其机理，并进一步揭示眼前房植入免疫抑制缓释药物防治角膜移植排斥的靶点，指导新剂型的研发和应用。

角膜移植手术是角膜盲复明的主要手段，但术后的免疫排斥是导致移植失败的最主要原因。目前在角膜移植领域主要存在两大科学问题：角膜移植免疫排斥的机理不清楚、术后常规药物治疗效果不佳。本课题主要围绕“虹膜-睫状体-房水”途径在角膜移植排斥中的关键作用与机制开展系列研究，并取得如下研究进展：①通过比较不同给药方式对角膜移植免疫排斥的影响，证实“虹膜-睫状体-房水”途径是防治角膜移植免疫排斥反应的另一关键途径。②揭示角膜移植早期“虹膜-睫状体-房水”途径启动的关键机制：从蛋白质组学层面上发现虹膜-睫状体组织内的同种异体免疫活性在角膜移植免疫排斥出现前就已显著增强；机制上，移植应激引起的供体角膜衰老、供体角膜植片产生的外泌体以及手术创伤引起的神经肽P物质的释放等诸多因素协同参与启动虹膜-睫状体内的同种异体免疫反应。③明确效应阶段该途径促进角膜移植免疫排斥反应的作用机制：眼内免疫排斥微环境破坏Treg细胞的免疫抑制功能，并呈现效应T细胞功能；在机制上，Treg细胞免疫功能下降与NF-κB转录因子c-Rel活性增强、天冬酰胺酶Caspase8导致Foxp3蛋白稳定性降低等密切相关。此外，免疫微环境中的细胞外ATP通过激活NLRP3炎症小体引起Th17免疫反应，并最终促进角膜移植免疫排斥。④阐明眼前房植入CsA缓释药物（CsA-DDS）防治角膜移植免疫排斥反应的机理：从蛋白质组学层面上发现CsA-DDS通过同时抑制“虹膜-睫状体-房水”途径与角巩膜缘途径发挥抗排斥效果，并重点从虹膜-睫状体内的血-房水屏障、眼前房免疫偏离等角度明确CsA-DDS防治角膜移植免疫排斥反应的作用机理。本课题的系列研究表明“虹膜-睫状体-房水”途径是防治角膜移植排斥反应的另一关键途径，不仅在理论上丰富角膜移植免疫排斥理论体系，还对抗排斥药物新剂型的研发和临床应用具有现实的指导意义。到目前为止，在本项目的资助下发表学术论文48篇；授权专利2项（PCT专利1项）；“眼内植入缓释药物”专利获得成功转让。