老年多器官功能障碍综合征肺组织IL-6的变化和意义

Changes and significance of IL-6 in lung tissue in rat model of multiple organ dysfunction syndrome in the elderly

目的探讨肺组织中IL-6含量及mRNA表达在老年大鼠多器官功能障碍综合征(MODS)中的变化和意义。方法 80只SD大鼠分为老年组(20个月龄)和青年组(3个月龄)各40只,建立油酸/脂多糖(OA/LPS)二次致伤老年MODS和青年MODS模型。观察对照组及伤后2、6、24h,重要器官(肺、心、肝、肾)病理及功能的变化,通过ELISA方法检测上述组织中IL-6含量,IL-6 mR-NA表达用RT-PCR法检测。结果 OA/LPS二次致伤MODS模型,肺脏是损害出现最早也是最重的器官,致伤后2 h青年组和老年组PaO_2即显著下降至最低值(P<0.01),伤后6 h,心、肝、肾生化指标达峰值(P<0.05),在相同时相点老年鼠脏器损害重于青年鼠(P<0.05)。致伤2 h后肺、心、肝和肾组织中IL-6 mRNA表达及蛋白含量均显著升高(P<0.05),且持续高于正常对照组(P<0.05),以肺组织中升高幅度最大,老年组显著高于同时相点青年组(P<0.05)。结论老年MODS过程中肺损伤出现最早且严重,其原因可能与OA/LPS致伤早期老年鼠肺组织中IL-6 mRNA表达及蛋白含量迅速升高有关。

Objective To study the changes and roles of interleukin-6 （IL-6） in lung tissue in rat model of multiple organ dysfunction syndrome （MODS） in the elderly. Methods Models of MODS in the elderly and in the young were established by injection of oleic acid （OA） at the dose of 0.25 ml/kg and lipopolysaccharide （LPS） at the dose of 3.5 mg/kg into SD rats （4 h interval）. A total of 40 3-month-old SD rats and 40 20-month-old SD rats were randomly divided into four groups respectively ： control group （ n = 10） and three model groups （n = 10 in each group） of 2, 6, and 24 h groups. The changes of pathomorphology and function of lung, heart, liver and kidney were observed. The IL-6 contents in plasma and in the lung, heart, liver, and kidney were determined with enzyme linked immunosorbent assay （ELISA）. Semiquantitative RT-PCR was used to measure mRNA expression of IL-6 mRNA in lung, heart, liver, and kidney tissues. Results After injection of OA and LPS into the young and elderly rats, the lung was injured first and PaO2 decreased to minimum at 2 h. Biochemical indexes of functional lesion of heart, liver and kidney increased to the peak level at 6 h. Organs were injured more seriously in elderly group than those in young group at the same time points （ P 〈 0.05 ）. The expression of IL-6 mRNA and the concentration of IL- 6 in different tissues increased significantly at 2 h after LPS injection （ P 〈 0.05 ）. The expressions of IL-6 mRNA in different tissues were higher in elderly group than those in young group at the same time points （P 〈 0.05）. Conclusion The early and serious presence of lung injury in elderly MODS rats may be associated with the rapid increase in IL-6 mRNA and protein contents in the lung tissues of elderly rats with OA- LPS-mediated lung injury.