全反式维甲酸诱导小鼠同种异基因角膜移植后“调节性T细胞－Th17细胞平衡”偏移及其机制研究

Immunological rejection is the major cause of graft failure after allogenic penetrating keratoplasty. Regulatory T cells(Treg)-Th17 balance plays a crucial role in determining the outcome of allogenic cornea grafts. CD4+CD25+Foxp3+ Tregs have strong immunosuppressive potent and anti-inflammatory properties, inducing immunological tolerance of grafts and prolonging transplant function. Meanwhile, Th17 are involved in acute allograft rejection. It can be proposed that skewing the response towards Treg and away Th17 might be beneficial for graft. It has been shown that in vitro studies, all-trans retinoic acid(ATRA) has been shown to upregulate the expression of Foxp3, prohibit the activation of Th17, and skew Treg-Th17 balance towards Treg, meaning for its protective effect on allogenic graft. However, its in vivo effect on Treg-Th17 balance and molecular mechanism remains unclear or controversial. Therefore, we plan to evaluate the effect of ATRA on Treg-Th17 balance after allogenic penetrating keratoplasty in mice, determine the shift of Treg-Th17 profile caused by ATRA, evalute its correlation with graft outcome, and explore its molecular mechanism by focusing on signal transduction and transcription regulation. Our study not only has great significance in introducing the application of ATRA in the treatment of immunological rejection, but also provides a potential therapeutic direction in treating immunological rejection after solid organ or tissue transplantation.

Treg-Th17在角膜移植免疫排斥反应中的作用是近年的研究热点，前者能延长角膜植片存活时间，而后者则促进植片排斥；两者处于动态平衡，一定条件下可以相互转化。全反式维甲酸(ATRA)在体外可以促进Treg活化、抑制Th17分化，促使Treg-Th17平衡向Treg偏移，有利于保护移植物。但是ATRA对Treg-Th17的体内效应及其调控Treg-Th17平衡的作用机制尚存争议。本研究以小鼠异基因角膜移植模型为基础，研究ATRA对受体Treg-Th17平衡的影响，及其与植片预后的相关性；观察ATRA能否阻止Treg向Th17转化，明确ATRA对Treg-Th17平衡的作用位点；使用蛋白质芯片、染色质免疫共沉淀（CHIP）等手段探讨ATRA影响Treg－Th17轴平衡偏倚的分子机制。本研究不但对于将ATRA开发为抗排斥药物具有积极意义，而且为角膜移植术后免疫排斥反应领域的研究提供新的发展方向。

角膜移植是角膜盲患者脱盲增视的主要手段，免疫排斥反应是造成手术失败的主要原因。角膜移植后的免疫排斥反应与活化的调节性T细胞（Treg） 水平降低和Th17 水平升高均存在联系。Treg-Th17细胞的动态平衡对决定移植物的最终预后具有重要意义。本项目利用小鼠同种异基因角膜移植模型，探讨反式维甲酸（All-trans retinoic acid, ATRA）在体内和体外环境下对Treg-Th17细胞平衡点偏移的调控效应、分析Treg-Th17细胞平衡点偏移与植片的存活时间之间的相关性。在此基础上，深入探讨ATRA调控Treg-Th17细胞平衡点偏移的作用机制，重点研究ERK信号通路和P38信号通路在ATRA调控机制中发挥的作用。本研究不但对于将ATRA开发为抗排斥药物具有积极意义，而且为角膜移植术后免疫排斥反应领域的研究提供新的发展方向。