移植肺局部IL-35水平增高抗小鼠肺移植急性排斥反应的基础研究

Allograft rejection has been one important problem in the field of organ transplantation. The suppression of T cell functions of recipients gives an effective prevention of immunological rejection post transplantation. Investigations have demonstrated that interleukin-35（IL-35）shows anti-rejection potential because of its amplification and enhancement effects on Tregs cells. And some studies suggested that up-regulation of IL-35 level through IL-35 gene injection inhibited allograft rejection and mitigated acute graft-versus-host disease. However, there were no reports cocerning more benefits of high-level of IL-35 in graft post transplantation. Our previous studies indicated that mesenchymal stem cell (MSC) was easy to be genetically modified and tended to graft retention post lung transplantation. Here, to take full advantage of this property, we will achieve IL-35 local overexpression in lung grafts by retrovirus infection of MSC and intravenous injection to recipient mice received allogeneic lung transplantations. The anti-transplant rejection effect on lung transplant acute rejection will be evaluated combined bioluminescence imaging. The exploration of relevant mechanisms can provide new immunosuppressive strategy for clinical therapy.

移植排斥反应是目前器官移植领域面临的重要问题，抑制受体T细胞功能是阻断器官移植后移植排斥反应的有效方法。白细胞介素-35（IL-35）可增强调节性T细胞（Treg）增殖与功能，具有抗移植排斥反应的潜力。研究证实提高器官移植受体IL-35水平能抑制移植后的排斥反应和减轻抗异基因骨髓移植的急性移植物抗宿主病。但是，目前还没有移植物局部高表达IL-35干预移植后排斥反应的相关研究。本项目利用间充质干细胞（MSC）易于被外源基因修饰以及尾静脉注射后倾向于滞留在移植肺部的特点，拟采用逆转录病毒载体修饰MSC实现IL-35的稳定表达，尾静脉注射到接受异基因肺移植的受体小鼠体内，结合生物发光成像技术探究移植肺局部IL-35过表达对肺移植急性排斥反应的作用及相关机制，为临床免疫抑制治疗提供新的有效方法。

白介素35（interleukin-35，IL-35）是IL-12家族一个新的免疫抑制因子，最早发现由天然型调节性T细胞（natural regulatory T cells，nTregs）特异性分泌，可促进Tregs细胞增殖并减少辅助性T细胞17（T helper 17 cell，Th17）数量，在多种炎症性疾病模型中都表现出良好的治疗作用。作为一种细胞因子，IL-35在体内半衰期短，全身性给药要求剂量较大且有效剂量不好把握，因此局部稳定给药可能是实现IL-35的治疗更安全有效的方式。本研究利用大肠杆菌（E.coli）作为肠道固有菌株以及尾静脉注射的间充质干细胞（mesenchymal stem cells，MSCs）易于在肺部滞留的特性，通过灌胃IL-35修饰的E.coli治疗葡聚糖硫酸酯钠（dextran sulfate sodium，DSS）诱导的小鼠溃疡性结肠炎（ulcerative colitis，UC），并且通过尾静脉注射IL-35修饰的MSCs治疗细菌脂多糖（lipopolysaccharides，LPS）诱导的小鼠急性肺损伤（acute lung injury，ALI），探讨两种给药方式在上述炎症模型中的应用。结果发现两种给药方式可以有效增加IL-35在病灶及血液中的浓度，减轻炎性损伤及炎性细胞的浸润，促进Tregs增殖和IL-10分泌，减少Th17细胞数量和IL-6表达，为炎症性疾病的治疗提供了新的思路和方法。