HDACi联合供体特异性输注诱导心脏移植免疫耐受的作用及其机制研究

The induction of transplant immune tolerance is “Holy Grail”, which is organ transplant experts looking for. Such tolerance induced by biological agents, such as anti-thymocyte globulin or OKT3, only removing peripheral reactive T cells, is not the real immune tolerance, but the sustained immunosuppression. HDACi suppresses the activation and proliferation of T cells, and subsequently promotes the apoptosis of T cells. Simultaneously, HDACi promotes the proliferation of Treg and inhibits the function of effector T cells. In this study, DST is applied for activating effector T cells, and HDACi (FK228) for suppressing the proliferation of the reactive T cells, in order to induce T-cell apoptosis and remove the reactive T-cell clone in allogeneic murine heart transplantation model. Meanwhile, HDACi increases the function of Treg and induces inhibitory cytokine secretion and shifts the balance among Th1, Th2 and Th17 cells to immune supression, which could maintain the antigen-specific immune tolerance. Furthermore, we will investigate the distribution, functional characteristics, mechanisms of intracellular signaling pathway, cell cycle regulation, proliferation and apoptosis of T lymphocytes. This study may provide new strategies for exploring donor antigen-specific immune tolerance.

诱导同种抗原特异性免疫耐受是器官移植致力探寻的“圣杯”。基于抗体等生物制剂清除外周同种反应性T细胞所诱导的耐受，并非真正意义上的耐受，而只是维持一种持续免疫抑制状态。我们前期研究发现组蛋白去乙酰化酶抑制剂（HDACi）可抑制效应T细胞活化增殖，促进其凋亡；同时可促进Treg增殖并增强其抑制功能，延长移植心存活。本研究拟在小鼠心脏移植模型中利用供者特异性输注使受者同种反应性T细胞活化，再给予HDACi抑制活化T细胞增殖，诱导其调亡从而清除该T细胞克隆。同时，利用HDACi对于Treg的效应，通过抑制性细胞因子分泌增加及调节T细胞免疫偏移，诱导移植耐受。此外，通过心脏移植模型、免疫重建模型，在细胞及分子水平对耐受诱导中免疫细胞的分布特点、功能特征及胞内信号传导通路相关机制、细胞周期调控、增殖与凋亡进行探讨，为探索供者特异性耐受策略提供新思路。

诱导同种抗原特异性免疫耐受是器官移植致力探寻的“圣杯”。基于抗体等生物制剂清除 外周同种反应性T细胞所诱导的耐受，并非真正意义上的耐受，而只是维持一种持续免疫抑制状态。我们前期研究发现组蛋白去乙酰化酶抑制剂(HDACi)可抑制效应T细胞活化增殖，促进其凋亡;同时可促进Treg增殖并增强其抑制功能，延长移植心存活。本研究发现在MHC-I错配的小鼠心脏移植模型中利用供者特异性输注（DST）使受者同种反应性T细胞活化，再给予HDACi（FK228）抑制活化T细胞增殖，诱导其调亡从而清除该T细胞克隆，还可抑制供体骨髓来源的树突状细胞活化及炎性因子产生。将FK228与DST联合应用可诱导小鼠MHC-I错配心脏移植物耐受，经二次皮肤移植验证其为对供体的特异性耐受。通过流式、PCR、ELISA、病理组化、WB、免疫共沉淀及免疫荧光方法进一步研究发现FK228可能通过增加组蛋白H3的乙酰化，进而影响IRE1α-XBP1通路及Smad通路发挥作用。目前研究成果证明了FK228联合DST可促进MHC-I错配的小鼠心脏移植模型免疫耐受，有望为新型免疫抑制剂的开发及移植免疫耐受的诱导提供新思路，为进一步的临床应用奠定理论和实验基础。