休克期切痂对烫伤大鼠γ干扰素、白细胞介素4 mRNA表达的影响

目的探讨烫伤大鼠伤后不同时间切痂对Th1细胞因子γ干扰素(IFN-γ)和Th2细胞因子白细胞介素4(IL-4)循环水平的变化及其mRNA在脾脏T淋巴细胞表达的影响。方法160只健康雄性Wistar大鼠背部30％Ⅲ度烫伤后,随机分为单纯烫伤对照组和伤后8h、24h、96h切痂组,分别在伤后4、12、24、48、96、120、168h活杀动物,采集血液和脾脏标本。ELISA法检测血浆内IFN-γ、IL-4浓度;Ficoll分离液法、贴壁法和尼龙毛柱吸附法提取纯化脾脏T淋巴细胞,一步法提取细胞总RNA、RT-PCR法扩增目的基因、琼脂糖凝胶电泳分析IFN-γ和IL-4 mRNA的表达。结果烫伤4h大鼠循环内上述细胞因子的浓度大幅升高,同时其mRNA表达迅速上调。Th1型细胞因子IFN-γ及其mRNA表达在烫伤后24h达峰值,其后逐渐下降;Th2型细胞因子IL4的循环浓度及mRNA表达进行性增加;伤后7d出现明显偏向Th2型反应的现象。切痂组两个细胞因子浓度增加及其mRNA表达上调的变化幅度小于单纯烫伤对照组,其中8h切痂组的变化最小,24h和96h切痂组次之。结论休克期切痂有利于抑制严重烧伤后Th2型细胞因子的过度表达。

Effects of escharectomy during burn shock stage on the mRNA expression of IFN-gamma and IL-4 in spleen T lymphocytes in rats after thermal injury

OBJECTIVE: To determine the serum level and mRNA expression of type-1/type-2 cytokines of T lymphocytes in spleens of rats after thermal injury and to investigate the effects of escharectomy during burn shock stage on IFN-gamma and IL-4. METHODS: One hundred and sixty male Wistar rats were randomized into four groups. In group A, animals were not subjected to escharectomy. In groups B, C and D, escharectomy and skin allograft were performed at 8, 24, 96 hours postburn (PB) respectively. At 4, 12, 24, 48, 96, 120 and 168 hours PB, animals were killed and blood and spleens samples were harvested. ELISA was applied to determine the concentration of IFN-gamma and IL-4 in serum. The expression pattern of IFN-gamma and IL-4 were observed at mRNA level in T lymphocytes isolated from spleen by RT-PCR. RESULTS: The serum level of IFN-gamma and IL-4 rose rapidly and significantly after scald injury, expression of IFN-gamma and IL-4 mRNA in rats' T lymphocyte were also up-regulated spontaneously. The serum level of IFN-gamma and its mRNA expression began to rise within 4 hours PB, peaking at 24 hours PB. Whereas IL-4 and its mRNA expression showed a persistent elevation. Thereby leading to a dominant tendency of Th2 cytokine response on 7 d PB. In group A all above parameters revealed most obvious changes compared with controls, then ranked in group D, B and C. CONCLUSION: Escharectomy during burn shock stage is helpful to decrease the harmful over expression of Th2-type lymphocyte after severe thermal injury.