大鼠小肠移植中细胞凋亡发生的阶段性及其意义

Development of apoptosis after small bowel transplantation in rats

目的研究同种异体大鼠小肠移植后移植肠缺血再灌注、排斥反应与细胞凋亡的关系以及相关肠系膜淋巴结(GALT)中出现凋亡细胞的意义。方法选用近交系F344/N和封闭群Wistar/A大鼠建立异位小肠移植模型,同时根据移植肠是否缺血预处理分为4组:同基因移植组(A组)、同基因缺血预处理组(A+组)、异基因移植组(B组)、异基因缺血预处理组(B+组),未行移植F344/N大鼠为空白对照。每组术后2h、1d、3d、5d、7d分别处死4只大鼠,获取移植肠及相关肠系膜淋巴结分别行组织病理学检查、TUNEL法检测细胞凋亡以及电镜观察。结果术后2h:A+、B+组移植肠细胞凋亡数量显著增加;术后1d:A+、B+组移植肠细胞凋亡数量均明显减少,而B、B+组相关肠系膜淋巴结细胞凋亡数量明显增加;术后3d、5d、7d:B、B+组移植肠细胞凋亡数量呈渐进性增加,而相关肠系膜淋巴结细胞凋亡数量呈渐进性减少。结论排斥反应和缺血再灌注损伤均可引起细胞凋亡,早期移植肠第1次出现凋亡细胞系缺血再灌注损失所致,移植肠第2次细胞凋亡数量增加则是排斥反应的标志。早期移植肠相关肠系膜淋巴结细胞凋亡数量增加与排斥反应有关并发生于排斥反应出现前。

Objective To investigate the development of apoptosis during ischemia/reperfusion （IR） injury and acute rejection, and to explore the significance of apoptosis in the Graft Mesenteric Lymph Node （GALT） in a rat heterotopic small bowel transplant （SBT） model. Methods SBT was performed in F344/N rats with either freshly harvested or preserved （4 h, in ringer lactate solution at 4 ℃ ） syngeneic and allogeneic （Wistar/A-F344/N） grafts. Bowel and GALT samples were collected 2 h after reperfusion and on small bowel transplant postoperative days （POD） 1, 4, and 7. Histopathology assessment of the graft and GALT were prepared for hematoxylin-eosin （H＆E） staining. Apoptosis was detected by the TUNEL and the electron microscope. Results The number of apoptotic cells 2 h after reperfusion increased profoundly in association with preservation. After a significant decrease on POD 1, the apoptotic cells rose again between POD 3 and 7 only in allogeneic grafts. On the other hand, the apoptotic cells in allogeneic GLAT markedly increased from POD 1 to day 3; at that time point, neither histological findings of rejection nor increase in apoptotic crypt cells were present in the graft jejunum. Conclusion IR injury and acute rejection may both induce extensive apoptosis. The graft jejunum distinct second increase in apoptosis may be an early and specific sign of acute rejection. Apoptosis of GLAT cells was well correlated with and ahead of progression of acute rejection.