高原不同海拔地区大鼠严重烫伤延迟复苏后肾组织细胞凋亡及Bcl-2蛋白的表达

Apoptosis and Bcl-2 protein expression in rat kidney tissue after severe burn with delayed fluid resuscitation in areas of different altitude

目的探讨高原不同海拔地区大鼠严重烫伤延迟复苏后肾脏组织Bcl-2蛋白的表达及其与肾组织细胞凋亡的关系。方法雄性Wistar大鼠240只,分别在1517m和3848m两个海拔高度建立30%TBSAⅢ度高原烫伤模型,随机分为即时复苏组(IFR组,伤后即刻腹腔注射等渗盐水4ml/kg,n=60)、延迟复苏组(DFR组,伤后6h开始按4ml/kg补液,n=50)和假烫对照组(NC组,n=10),分别于伤后1、6、12、24、72和168h取材,采用组织芯片技术和原位末端标记法(TUNEL)检测肾组织细胞的凋亡,免疫组织化学染色与图像分析技术检测肾组织Bcl-2蛋白的表达。结果随着海拔梯度上升,肾小管上皮细胞发生水肿、颗粒变性、坏死及崩解;肾小球毛细血管出现不同程度扩张、充血,内皮细胞变性及坏死;肾间质充血、水肿及炎性细胞浸润。病变程度DFR组较IFR组加重,高海拔地区较低海拔地区加重。肾组织细胞凋亡率和Bcl-2蛋白表达水平DFR组高于IFR组,高海拔地区高于低海拔地区(P<0.001),且二者呈明显正相关(r=0.516,P<0.001)。结论高原严重烧伤导致的肾损伤与肾小管细胞凋亡有关,而凋亡抑制因子Bcl-2的高表达反映了损伤过程中细胞自我保护机制的增强。

Objective To observe the changes in Bcl-2 protein expression in rat kidney tissue after severe burn with delayed fluid resuscitation in areas of different altitude, and explore the relationship between its expression and cell apoptosis. Methods The experiments were performed at two altitudes （1 517m and 3 848m）. A 30%0 TBSAⅢ° scald model was reproduced with 240 male Wistar rats （120 rats for each altitude）. Rats were randomly assigned into delayed fluid resuscitation group （DFR, n=50）, immediate fluid resuscitation group （IFR, n=60） and normal control group （NC, n=10）. Renal tissue samples were harvested at 1, 6, 12, 24, 72 and 168 hours after scald, respectively. The cell apoptosis was detected by tissue chips technic and terminal uridin nick end labeling （TUNEL）. The expression of Bcl-2 was detected by immunohistochemistry and image analysis. Results In higher altitude, cellular edema, granular degeneration, necrosis and disintegration of renal tubular epithelial cells; dilation and engorgement of renal glomerular capillaries, degeneration and necrosis of endothelial cells, and congestion, edema and inflammatory cell infiltration in renal interstitium were found. The pathological changes were more serious in DFR group than that in IFR group, and they were worse in the rats at 3 848m altitude than that in those rats at 1 517m altitude. The levels of cell apoptosis and Bcl-2 protein expression were higher in DFR group than that in IFR group, and in the rats at 3 848m altitude than that in those rats at 1 517m altitude （P〈0. 001）. There existed significant positive correlation between the altitude and the pathological changes, and also between cell apoptosis and Bcl-2 protein expression of the renal tissues of scald rats （r=0. 516, P〈 0. 001）. Conclusion Kidney injuries caused by severe scald at high altitude area are related to apoptosis of renal tubular cells, and the high expression of apoptosis inhibiting factor bcl-2 reflects the enhancement of self-protective mechanism in the course of injury.