脓毒症大鼠肝组织内IL-6／信号转导和转录激活因子3的表达变化及可能作用

Expression and functional role of interleukin-6 and signal transducer and activator of transcription 3 in liver injury of rats with sepsis

目的研究IL-6／信号转导和转录激活因子3（STA33）信号通路在脓毒症大鼠肝组织中的活化规律及其与肝损害的关系。方法盲肠结扎穿孔（CLP）法制作脓毒症大鼠模型，66只大鼠随机分为正常对照组、CLP组和假手术组，分别于术后2，6，12，24，48h处死，采用实时荧光定量多聚酶链式反应（real-time PCR）和ELISA法分别检测肝组织中IL-6基因与蛋白表达，免疫组织化学法检测肝组织磷酸化STA33（P-STA33）的表达，同时测定血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）水平，光镜观察肝组织形态学变化。结果CLP组大鼠肝组织IL-6与P-STA33表达术后2h开始升高，12h达峰值，血清ALT和AST在术后24h达高峰，肝组织12h后出现炎症改变，P-STAT3表达与IL-6、肝功能变化均呈正相关（P〈0．05）。假手术组大鼠各项指标与正常对照组比较，差异无统计学意义（P〉0．05）。结论IL-6／STA33信号通路可能在诱导脓毒症动物肝脏急性损伤中具有重要作用。

Objective To investigate the activation mechanism of interleukin-6 and signal transducer and activator of transcription 3 （IL-6/STAT3） pathway in the injured liver of rats with sepsis and its possible role in occurrence of liver injury. Methods The rat model of sepsis induced by ceal ligation and puncture （CLP） was established and 66 female Wistar rats were divided randomly into control group （ n = 6）, sham operation group （ n = 30） and CLP group （ n = 30）. Animals in each group were sacrificed at various time points （2, 6, 12, 24, 48 hours after CLP）, Gene and protein expression of IL- 6 and expression of phosphorylated STAT3 （P-STAT3） in the hepatic tissue were detected by real-time fluorescence quantitative PCR （ FQ-PCR）, ELISA and immunohistochemical method respectively. Serum alanine transaminase （ALT） and aspartate aminotransferase （AST） levels were assayed and the changes in hepatic histomorphology were observed under light microscope. Result The expressions of IL-6 and P-STAT3 in CLP group were significantly enhanced at 2-48 hours after CLP （ P 〈 0.01 ）, peaking at thel 2 hour and the serum ALT and AST contents peaked at the 24th hour （ P 〈 0.05 or P 〈 0.01 ）. There were detectable pathological changes in CLP group at the 12 hour after CLP. The difference were not statistically significant between control group and sham group （ P 〉 0.05 ）. It was shown that expression of P-STAT3 was positively correlated with expression of IL-6 and the changes in hepatic function （P 〈 0.05 ）. No significant difference was found in the above indices between sham operation group and control group. Conclusion IL-6/STAT3 pathway may be heavily involved in acute liver injury in rats with sepsis.