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低氧诱导因子-1a的表达

Cell apoptosis and expression of hypoxia-inducible transcription factor-1a in kidney tissue after severe burn with delayed fluid resuscitation in rats 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组织低氧诱导因子-1a（HIF—1a）的表达及与细胞凋亡的关系。方法雄性Wistar大鼠240只，建立高原烫伤模型[30％总体表面积（TBsA）Ⅲ度烫伤]，分别在1517m和3840m两个海拔高度将大鼠随机分为延迟复苏组（DFR，n=50）、即时复苏组（IFR，n=60）和正常对照组（CG，n=10）。分别于伤后1、6、12、24、72和168h从右肾组织取材，采用大组织芯片技术和原位末端缺刻标记法（TUNEL）检测肾组织细胞凋亡，用免疫组化染色技术与图像分析技术检测肾组织HIF—1a的表达。结果随海拔梯度上升，肾小管上皮细胞水肿、颗粒变性、坏死及崩解；肾小球毛细血管不同程度扩张、充血，内皮细胞变性、坏死；肾间质充血、水肿，炎性细胞浸润。DFR组较IFR组、高海拔较低海拔地区病变均明显加重。随海拔梯度上升，细胞凋亡和HIF—1a表达均增强，阳性表达均位于肾小管上皮细胞的胞核上；其表达强度DFR组和IFR组均高于CG组，高海拔组高于低海拔组，同一海拔高度DFR组高于IFR组（P均〈0．01）。细胞凋亡指数与HIF—1a阳性表达灰度值呈负相关（r=0．651，P〈0．01）。结论高原地区不同海拔高度严重烫伤可导致HIF—1a表达增强，同时伴肾小管细胞凋亡增加。肾损伤与肾组织细胞凋亡有关；表明HIF—1a可能参与了肾组织细胞凋亡。

Objective To explore the relationship of cell apoptosis and expression regularity of hypoxia-inducible transcription factor （HIF）-1a after severe burn with delayed fluid resuscitation in areas of different altitude. Methods A total of 240 male Wistar rats, which were raised in areas of different altitude （1 517 and 3 840 meters）, were employed as the experimental models [They received a 30% total body surface area （TBSA） Ⅲ degree scald injury ], and then they were randomly divided into 3 groups： delayed fluid resuscitation group （DFR, n=50）, immediate fluid resuscitation group （IFR, n = 60） and control group （CG, n= 10）. Renal tissue samples were harvested at 1, 6, 12, 24, 72 and 168 hours after burn, respectively. Cell apoptosis was detected by tissue chip technology and terminal deoxynucleotidyl transferase- mediated dUTP biotin nick end labeling （TUNEL）. The expression of HIF-1a was assessed by immunohistochemistry and image analysis. Results With increase in altitude, cellular edema, degeneration, necrosis and disintegration of renal tissue were gradually worsening, the capillaries of renal glomeruli became dilated and engorged, with degeneration and necrosis of endothelial cells, engorgement and edema of renal interstium, and infiltration of inflamatory cells. Pathological changes in DFR group were more serious than that of IFR group. Cell apoptosis and the expression of HIF-1a were both enhanced, the latter mainly appeared in nuclei of renal cells, and they were more marked at 3 840 meters compared with those at 1 517 meters. They were more marked in experimental groups than in control group, especially so in DFR group （P〈0.01）. Cell apoptosis was positively correlated with the expression of HIF-1a （r = 0. 651, P〈0. 01）. Conclusion Severe burn at high attitude plateau results in high expression of HIF-1a and an increase in apoptosis of renal cells. HIF-1a plays a role in kidney cell apoptosis.