摘要
目的探讨烫伤后不同组织肿瘤坏死因子(TNF-α)mRNA 的动态表达及其与内毒素血症的关系。方法采用大鼠35%体表面积Ⅲ度烫伤模型,实验动物随机分为正常对照组、烫伤组、多粘菌素 B 治疗组。血浆内毒素水平采用改良过氯酸预处理血浆偶氮显色法鲎试验定量测定;组织 TNF-α mRNA 含量采用逆转录聚合酶链反应检测。结果烫伤后门静脉及体循环内毒素水平均显著升高,8h 达高峰,24h 则逐渐下降。给予低剂量多粘菌素 B 治疗可显著降低门静脉内毒素峰值(P<0.05)。另一方面,烫伤后2h 肺、肝、肠、肾等组织 TNF-α mRNA 表达较伤前值即有显著升高(P<0.05～0.01),烫伤后8h 达高峰,约为伤前值的1.7～2.6倍,且一直持续至伤后24h。给予多枯菌素 B 抗内毒素治疗后可不同程度抑制 TNF-α mRNA 的表达(P<0.05～0.01)。相关分析显示,门静脉内毒素水平同肺、肠、肾组织 TNF-α mRNA 呈显著正相关关系(r 值分别为0.365,0.381,0.484,P<0.05),但与肝组织无显著相关。结论肺、肝、肠、肾等组织 TNF-α mRNA 表达在烫伤早期即显著增多,并呈一逐渐升高的趋势。创伤后内毒素血症对机体多种组织 TNF-α基因表达具有重要影响。
Objective To investigate the dynamic changes in tumor necrosis factor-α(TNF-α) mRNA expression and the relationship between TNF-α mRNA and gut-derived endotoxemia in rats after thermal injury.Methods 56 male Wistar rats were subjected to a 35% total body surface area full-thick- ness thermal injury and randomly divided into 3 groups:normal controls,35% Ⅲ° injury group,and polymyxin B treatment group.Plasma endotoxin was measured by limulus amebocyte lysate test,and tis- sue TNF-α mRNA expression was determined by reverse transcription polymerase chain reaction(RT- PCR).Results It was found that a significant elevation of endotoxin concentration in both portal and systemic circulation was observed at 2 hours after thermal injury,peaking at 8 hours(P<0.05～0.01) and lowering at 24 hours.Meanwhile,TNF-α mRNA expression significantly increased in liver,lung,in- testine,and kidney at 2 hours,peaking at 8 hours,and a high level was maintained till 24 hours.Howev- er,treatment with a low-dose polymyxin B could lower both portal and systemic endotoxin levels,and markedly inhibit TNF-α mRNA expression in various organs.In addition,a positive correlation between portal endotoxin concentration and puhnonary,intestinal and renal TNF-α mRNA expression was noted (r=0.365～0.484,all P<0.05).Conclusion This study suggests that major burns can lead to a marked elevation of tissue TNF-α mRNA expression in vital organs,which may be associated with gut-de- rived endotoxemia caused by acute thermal injury.
基金
本课题受全军九五医药卫生青年基金及中国工程科技奖助基金资助(编号:96Q116)
