脓毒症大鼠肝脏组织Toll样受体4和髓样分化蛋白-2基因表达的变化规律

Regularity of change in gene expression of Toll-like receptor 4 and myeloid differentiation-2 mRNA in the liver of septic rats

目的探讨脓毒症大鼠肝脏组织内毒素复合受体--Toll样受体4 (TLR4)/髓样分化蛋白-2(MD-2)mRNA的表达变化,研究其与肝脏组织肿瘤坏死因子-α(TNF-α)mRNA表达的关系.方法腹腔注射内毒素(LPS)5mg/kg制作大鼠脓毒症模型.动物分为正常对照组(20只)及内毒素注射后1h、2h、6h组(各20只),检测肝脏组织TLR4/MD-2以及TNF-α mRNA的表达.结果 LPS注射后1h,TLR4/MD-2及TNF-α mRNA表达开始升高并达高峰,伤后2～6h逐渐下降,各时间点的表达量均显著高于对照组(P<0.01),TLR4与MD-2 mRNA的表达呈明显正相关(P<0.05),且分别与TNF-α mRNA的表达呈显著正相关(P<0.05).结论 LPS可迅速上调肝脏组织TLR4/MD-2的基因表达并诱导早期炎症细胞因子TNF-α的基因表达.脓毒症时TLR4识别LPS是可能以TLR4/MD-2复合体的形式完成的,且在识别过程中MD-2是TLR4必需的作用分子.

Objective To investigate the changes in Toil-like receptor 4 （TLR4） and myeloid differential protein-2 （MD-2） gene expression in the liver of septic rats, and to elucidate the relationship between the expression of TLR4/MD-2 mRNA and TNF-α mRNA. Methods .Sepsis model was reproduced in rats hy intraperitoneaI injection of LPS （5mg/kg）. 80 Wistar rats were randomly divided into 4 groups：normal control and lh, 2h, 6h after I.PS injection （20 rats for each group）. Rats were sacrificed at different time points, and the expression of TLR4/MD-2 mRNA and TNF-α mRNA in the Iiver was measured by RT-PCR. Results The expressions of TLR4/MD-2 mRNA and TNF-α mRNA were up-regulate, peaking lh after LPS injection, and then declined gradually 2-6h after LPS challenge. The expressions at every time point were higher than that in control group （P〈0.01）. The expression of TLR4 mRNA showed a positive correlation with that of MD-2 mRNA （P〈0.05）, and both of them showed a positive correlation with that of TNF-α mRNA （P〈0.05）. Conclusions LPS could lead to a quick up-regulation of TLR4/MD-2 mRNA expression in the liver, and induce the TNF-α expression in the early pro-inflammatory cells. The recognition of LPS by TLR4 must go through the TLR4/MD-2 complex, and MD-2 is a key regulatory molecule in sepsis.