PD-L1促进大鼠断尾再植成活及可能机制

The possible mechanism of PD-L1 promoting survival in rat tail replantation

目的研究程序性死亡受体-1(PD-L1)对断尾再植成活的影响,探讨可能的机制。方法建立大鼠断尾再植模型,随机选取40只断尾再植模型成功大鼠,分为两组:PD-L1组(术后立即环手术切口浸润注射重组大鼠PD-L1蛋白生理盐水溶液)和生理盐水组(术后立即环手术切口浸润注射生理盐水0.1ml),另取10只正常大鼠作为对照。ELISA检测手术前后各个时间点的血清样本中PD-L1水平,应用重组大鼠PD-L1蛋白干预断尾再植大鼠的断尾成活,评价术后断尾发生血管危象请况,Western blot法检测断尾再植大鼠尾组织中血管内皮生长因子(VEGF)、CD34蛋白表达水平。结果术后PD-L1水平显著增高(<0.05),至术后48 h时达最高值,之后开始降低,至术后7d接近术前水平。经重组大鼠PD-L1蛋白干预的大鼠断尾血液循环较好,血管危象发生几率显著低于生理盐水预处理组。与正常大鼠相比,PD-L1蛋白干预组、生理盐水干预组断尾再植鼠尾组织中VEGF、CD34蛋白表达水平均显著增高(<0.05),与生理盐水干预组相比,PD-L1蛋白干预组术后48h鼠尾组织中VEGF、CD34蛋白表达均显著增高(<0.05),术后12d鼠尾组织中仅见VEGF蛋白表达显著增高(<0.05)。结论 PD-L1促进断尾再植成活可能与上调VEGF及CD34表达相关。

Objective To explore the influence and the possible mechanism of programmed cell death-1（PDL1） on the cut-tail survival after rat tail replantation. Methods Rat tail replantation model was made, 40 successful rat tail replantation models were randomly selected,and divided into two groups：group PD-L1（infiltratively injecting recombinant rat PD-L1 protein in the ring operation incision）and saline group（infiltratively injecting normal saline in the ring operation incision）,another 10 rats were used as control. The serum level of PD-L1 was detected with ELISA method. After applying of recombinant rat PD-L1, the vascular crisis was evaluated in the rat tail replantation model. Vascular endothelial growth factor（VEGF） and CD34 expression levels in the cut-tail were detected by Western blot. Results Compared with preoperative rats, PD-L1 levels of postoperation rats at different time points were increased significantly, and reached the peak at 48 h after operation, then down to nomal level at 7d after operation. After applying of recombinant rat PD-L1, the blood circulation of cut-tail improved and vascular crisis rate was significant lower. Compared with normal rats, levels of VEGF and CD34 increased in cut-tail of model rats（P〈0.05）. The recombinant PD-L1 upregulated the levels of VEGF and CD34 at 48 h postoperation. Conclusion The promotion of cut-tail replantation survival by PD-L1 might be related to the upregulation of VEGF and CD34 expression.