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目的探讨 PD-L1.Ig 联合1,25(OH)_2D_3对大鼠胰腺移植急性排斥反应的免疫调控作用以及对大鼠移植胰腺存活时间的影响。方法以 F344大鼠为供体,Lewis 大鼠为受体,建立4组原位胰腺移植模型。每组12例,共48例。A 组:对照组、B 组:PD-L1.Ig 组、C 组:1,25(OH)_2D_3组、D 组:PD-L1.Ig+1,25(OH)_2D_3组;观察术后各组血糖变化,移植物存活以及组织病理学改变;流式细胞检测受体血、脾以及移植胰 CD4~+T 细胞、CD8~+T 细胞、CD4~+CD25~+T 细胞表达水平;酶联免疫吸附试验(ELISA)检测移植物局部白细胞介素(IL)-2、-4、-10、-12表达水平;于术后第7天分别杀死各组受体和供体鼠各2只,取受体脾细胞与供体作混合淋巴细胞反应(MLR)。结果与A比较,PD-L1.Ig 组并未显著延长移植胰腺存活时间(P>0.05),C、D 组对改善血糖水平和延长移植胰腺存活时间作用明显(P<0.01),其中,D 组移植胰腺存活时间最长(23.9±0.8)d;与 A 组比较,B 组无明显改善,C 组排斥反应较 A 组明显减弱,而 D 组几乎未发生排斥反应;CD3~+CD8~+T细胞计数 D、C、B 与 A 组比较均有减少,差异有统计学意义(P<0.01)。CD4~+T 细胞 D、C、B 与 A 组的差异有统计学意义(P<0.05)。CD4~+CD25~+调节性 T 细胞 A、B、C、D 组逐渐升高,差异有统计学意义(P<0.01),且以 D 组较为明显(C 组比 A 组 P<0.01);D 组明显抑制移植物局部 Th1型细胞因子 IL-2、IL-12的产生,显著提高 Th2型细胞因子 IL-4、10的水平;与对照组比较,各治疗组受体T淋巴细胞在 MLR 中表现对供体淋巴细胞特异性低反应性,能有效抑制 T 细胞对同种异体抗原的反应。结论共刺激阻断剂 PD-L1.Ig 联合1,25(OH)_2D_3可有效抑制细胞免疫应答,干预急性排斥反应,显著延长大鼠移植胰腺存活时间。
Objective To investigate the immunomodulatory effects of PD-L1.Ig combined with 1,25 (OH) _2D_3 on the acute rejection in rat pancreas transplantation and its effect on the survival time of rat pancreas. Methods F344 rats as donors and Lewis rats as recipients, four groups of orthotopic pancreas transplantation models were established. Each group of 12 cases, a total of 48 cases. Group A: control group, group B: PD-L1.Ig group, group C: 1,25 (OH) _2D_3 group, group D: PD-L1.Ig + 1,25 (OH) _2D_3 group; The changes of blood glucose, graft survival and histopathological changes were observed. The expression of CD4 ~ + T cells, CD8 ~ + T cells and CD4 ~ + CD25 ~ + T cells in recipient blood, spleen and pancreas were detected by flow cytometry. The expression of interleukin (IL) -2, -4, -10 and -12 in the grafts was detected by ELISA. At the 7th day after operation, the rats in each group were killed 2 , Take recipient spleen cells and donor for mixed lymphocyte reaction (MLR). Results Compared with A, the PD-L1.Ig group did not significantly prolong the survival time of transplanted pancreas (P> 0.05), and the effect of C and D group on improving blood glucose level and prolonging the survival time of transplanted pancreas was significant (P <0.01) The survival time of pancreas transplantation group was the longest (23.9 ± 0.8) days. Compared with group A, there was no significant improvement in group B, rejection in group C was significantly weaker than that in group A, and rejection in group D was almost absent. CD3 + CD8 + T cell count D, C, B compared with the A group were reduced, the difference was statistically significant (P <0.01). The difference of CD4 ~ + T cells in groups D, C, B and A was statistically significant (P <0.05). The numbers of CD4 ~ + CD25 ~ + regulatory T cells in groups A, B, C and D increased gradually (P <0.01), especially in group D (P <0.01). D group significantly inhibited the production of local Th1 cytokines IL-2 and IL-12, and significantly increased the level of Th2 cytokines IL-4 and 10. Compared with the control group, the receptor T lymphocytes of all treatment groups showed significant differences in MLR In the performance of donor lymphocyte-specific low reactivity, can effectively inhibit the T-cell response to allogenic antigen. Conclusions Costimulatory blocker PD-L1.Ig combined with 1,25 (OH) _2D_3 can effectively inhibit the cellular immune response, interfere with acute rejection and significantly prolong the survival time of transplanted pancreas in rats.