内毒素预处理对内毒素血症大鼠肺损伤的影响

Protective Effects of Endotoxin Pretreatment on Lung Injury of Rats with Endotoxemia

目的探讨内毒素预处理对内毒素血症大鼠肺损伤的保护作用。方法将雄性Wistar大鼠72只随机分成对照组、内毒素组和预处理组,每组24只。每组又按时间分为2 h组、4 h组、6 h组、12 h组4个亚组,每组6只。预处理组首次经腹腔注射脂多糖(LPS)0.25 mg/kg,24 h后再经腹腔注射LPS 0.5 mg/kg,其余两组给予等量生理盐水。第二次腹腔注射72 h后,内毒素组和预处理组经尾静脉一次注射LPS 10 mg/kg,对照组给予等量生理盐水。内毒素组和预处理组在第二次注射LPS后2、4、6、12 h,对照组在注射最后一次生理盐水后2、4、6、12 h,各取6只处死取肺组织免疫组化法检测肺组织白细胞间粘附分子1(ICAM-1)的表达,酶联免疫吸附法检测血清肿瘤坏死因子α(TNF-α),比色法检测肺组织丙二醛(MDA)和超氧化物歧化酶(SOD)。结果内毒素血症4 h时内毒素组肺组织ICAM-1、MDA和血清TNF-α水平均显著高于对照组[75.07±0.53比11.98±0.56,(3.93±0.42)μmol/g比(1.24±0.27)μmol/g,(478.62±45.58)pg/mL比(26.67±2.38)pg/mL,P<0.05],肺组织SOD水平显著低于对照组[(6.26±0.31)U/mg比(15.23±0.62)U/mg,P<0.05]。经内毒素预处理后,预处理组肺组织ICAM-1、MDA和血清TNF-α水平较内毒素组显著降低[42.40±0.44,(2.89±0.49)μmol/g,(376.76±43.67)pg/mL],肺组织SOD水平显著上升至(8.79±0.35)U/mg,差异有统计学意义(P<0.05)。结论内毒素预处理可减轻内毒素血症时的肺损伤,其机制可能与减少炎症反应和氧自由基生成有关。

Objective To investigate the protective effects of endotoxin pretreatment on lung injury of rats with endotoxemia. Methods The rat model of acute endotoxemia was established by injecting lipopolysaccharide （LPS） intraperitoneally. Seventy-two male Wistar rats were randomly divided into three groups,/e, a saline control group （ N, n = 24 ）, a LPS-treated group （ L, n = 24 ）, and a LPS pretreated group （P,n =24）. Each group was divided into 2 h,4 h,6 h,and 12 h subgroups. The rats in group P were firstly administered with introperitoneal injection of 0. 25 mg/kg LPS. After 24 hours, they were subjected to the injection of 0. 5 mg/kg LPS. The rats in group N and L received injection of equivalent amount of saline. After 72 hours, the rats in group L and P were challenged with intravenous injection of 10 mg/kg LPS, otherwise saline in group N. Six rats were killed at 2,4,6 and 12 hours respectively after injection of LPS in group L and P. The lungs were removed for detecting intercellular adhesion molecule-1 （ICAM-1）, superoxide dismutase （SOD） , and malondialdehyde （MDA）. Meanwhile the level of tumor necrosis factor- alpha （TNF-α） in serum was measured, and the pathological changes of lung were also examined. Results The contents of ICAM-1, MDA and TNF-α in the LPS-treated 4 h group were 75.07 ± 0. 53, （ 3.93 ±0. 42） ttmol/g,and （478. 62 ± 45.58 ）pg/mL respectively, significantly higher than those in the saline control group. The endotoxin pretreatment reduced the above indexes to 42. 40±0. 44, （2. 89±0. 49） ttmol/g and （376. 76 ± 43.67） pg/mL respectively （P 〈 0. 05 ）. The content of SOD in the LPS-treated 4 h group was （ 6. 26 ± 0. 31 ） U/nag, significantly lower than that in the saline control group. The endotoxin pretreatment increased SOD to （8.79 ±0. 35） U/mg. Conclusion Endotoxin pretreatment can suppress the progress of lung injury in rats with endotoxemia and protect the lung tissue by down-regulating the inflammatory response and oxygen free radical production.