ECDI结合供体脾细胞联合阻断OX40/OX40L通路诱导预致敏小鼠肾移植免疫耐受

It is a tough problem that how to induce immune tolerance in presensitized transplant recipients. Our previous studies have shown that ECDI-fixed donor splenocytes (ECDI-SP) could prolong the kidney allograft survival in rats and mice kidney transplant models, and induction of regulatory T cells (Treg) play a key role in this process, whereas ECDI-SP fail to prolong survival of the kidney allograft in presensitized recipients. Memory T cells (Tm) generated in presensitized recipients have been reported to play important roles in promoting rejection. OX40/OX40L costimulation pathway plays a key role in controlling Tm and Treg, and blockage of this pathway could inhibit Tm while promote Treg expansion. Based on the previous studies, we will investigate whether ECDI-SP combined with blockage of OX40/OX40L pathway can prolong kidney allograft survival in presensitized mice kidney transplant model. We will also investigate whether blockage of OX40/OX40L pathway can inhibit Tm and promote ECDI-SP inducing Treg expansion. In the mixed lymphocytes reaction experiment in vitro, we will further illustrate the possible molecular mechanisms that blockage of OX40/OX40L pathway synergize with ECDI-SP in inducing immune tolerance. The aim of the present study is to explore new methods for clinical application of inducing immune tolerance in presensitized transplant recipients.

如何诱导预致敏移植受者免疫耐受是当前器官移植领域的难题。我们的前期研究证实ECDI结合供体脾细胞（ECDI-SP）能够延长大鼠和小鼠移植肾存活时间，诱导调节性T细胞（Treg）产生在其中起关键作用，但ECDI-SP未能够延长预致敏小鼠移植肾存活时间。预致敏受者体内产生的记忆性T细胞（Tm）是促进排斥反应发生的重要因素，而OX40/OX40L共刺激分子是调控Tm和Treg的关键通路，阻断该通路可抑制Tm，促进Treg产生。本课题拟在前期研究基础上，采用预致敏小鼠肾移植模型，验证ECDI-SP联合阻断OX40/OX40L通路能否协同诱导小鼠移植肾长期存活，探讨阻断OX40/OX40L通路能否抑制Tm、促进ECDI-SP诱导Treg产生，并采用体外MLR实验进一步阐明阻断OX40/OX40L通路协同ECDI-SP诱导免疫耐受的分子机制，为临床诱导预致敏移植受者免疫耐受提供新的方法。

诱导预致敏受者免疫耐受可以避免急慢性排斥反应和长期服用免疫抑制剂相关的感染、肿瘤等并发症，延长移植受者存活时间。我们的研究结果表明，ECDI结合供体脾细胞（ECDI-SPs）联合抗OX40L抗体能够显著延长皮肤移植预致敏小鼠移植心脏存活时间，减轻炎症反应，降低炎症因子和抗供体抗体水平，抑制记忆性T细胞和体外MLR实验中细胞增殖。采用抗CD25抗体清除长期存活小鼠体内的Tregs后，免疫耐受被阻断；而过继输注预致敏小鼠来源T细胞（富含记忆性T细胞）给长期存活的小鼠可抑制Tregs并阻断免疫耐受，提示ECDI-SPs联合阻断OX40/OX40L通路通过抑制记忆性T细胞并促进Tregs产生从而诱导预致敏受者获得免疫耐受。本研究阐述了ECDI-SPs联合阻断OX40/OX40L通路诱导预致敏移植受者免疫耐受的可行性及其机制，为临床诱导预致敏受者免疫耐受提供新的思路。