Nrp1阳性细胞在移植肾免疫耐受诱导与维持中的调节作用及其机制

Allograft rejection remains a significant challenge to the success of solid-organ transplantation. Immunosuppression, the current anti-rejection therapy, has always been related to problems of morbidity and mortality as it affects the function of all responding T cells irrespective of their antigen specificity. Thus, enormous motivation and interest remains in inducing specific unresponsiveness (tolerance) to clinical solid organ allografts. CD25+ CD4+ Foxp3+ regulatory T cells are one of the key populations responsible for controlling immune responses to alloantigens and preventing rejection in vivo. However,the characterization and manipulation of Treg in vivo are still being retarded by lack of effective surface molecular markers, and by unclear interactions between Treg and other immune cell at the different stages of immune response after transplantation. Neuropilin protein 1 (Nrp1) has been reported to be the surface molecular marker in mouse Treg by us and other teams. However contrary results were found in human studies, and importantly in vivo investigation related to Nrp1 in Treg remains to be performed. Our preliminary studies found that in rejected grafts the percentage of Nrp1 positive cells among lymphocytes decreased significantly, suggesting the immune response status may affect Nrp1 expression in immune cells in vivo. On this basis, this project intends to use the mouse renal transplantation model and clinical transplant recipients biopsy specimens to study the change of immunological characteristics in Nrp1 positive cells after transplantation and its interactions with other immune cells.We intend to investigate the mechanism of immune tolerance induction and maintenance by down/up regulating Nrp1 expression or adoptive transfer of subtype Nrp1 positive T cells. The current project should be useful for future clinical anti-rejection treatment.

调节性T细胞（Treg）是介导移植免疫耐受的关键细胞群，最具临床应用前景，缺乏活化状态的表面标记是其应用瓶颈。国外学者及申请人的前期研究均发现神经纤毛蛋白1（Nrp1）可作为小鼠Treg的表面标记，但在人Treg的研究出现矛盾结果，且缺乏移植背景下的体内研究。根据文献分析和我们的近期研究结果，我们认为移植后免疫微环境可影响Nrp1在免疫细胞的表达，故推测Nrp1仍可能是人类移植受者Treg的重要表面标记，Nrp1+Treg的比例可能反映受者的免疫耐受程度。本课题拟采用小鼠肾移植构建排斥、免疫抑制和免疫耐受实验组，上调/下调Nrp1表达或过继回输亚型Nrp1+T细胞；结合临床肾移植受者标本，研究移植背景下Nrp1+细胞的免疫学特性和与其他免疫细胞交互作用，分析Nrp1+Treg比例与受者免疫状态间的关系，探究其在肾移植免疫耐受诱导与维持中的作用及其机制，为临床治疗排斥反应提供新的理论依据。

调节性T细胞（Treg）是介导移植免疫耐受的关键细胞群，最具临床应用前景，缺乏活化状态的表面标记是其应用瓶颈。国外学者及申请人的前期研究均发现神经纤毛蛋白1（Nrp 1）可作为小鼠Treg的表面标记，但在人Treg的研究出现矛盾结果，且缺乏移植背景下的体内研究。本研究成功建立了小鼠肾移植免疫排斥、免疫抑制和免疫耐受模型。发现免疫耐受组小鼠移植模型中肾组织、淋巴结、脾脏及外周血单核细胞中Nrp1表达明显增加，且Nrp1表达与Foxp3相关。IL-2干预后发现，CD4+Nrp1 high 细胞IL-8和IFN-γ等促炎性因子含量明显低于 CD4+Nrp1 low组，而IL-10和TGF-β等炎性抑制因子含量明显高于CD4+Nrp1 low组，提示Nrp1有可能抑制了炎性因子分泌。随后通过腺病毒转染建立Nrp1稳定表达下调的肾移植模型鼠，结果也表明Nrp1表达下调组受体鼠炎症程度较高。故Nrp1分子可能在免疫耐受中发挥重要作用，具有重要的临床意义。