髓样分化因子88对小鼠肠缺血再灌注致急性肺损伤的影响

Effect of myeloid differentiation factor 88 on acute lung injury induced by intestinal-ischemia reperfusion in mice

目的观察髓样分化因子88（MyD88）对小鼠肠缺血再灌注致急性肺损伤（ALl）的影响。方法6～8周龄雄性MyD88基因敲除小鼠（MyD88-α）和野生型C57BL／6J小鼠各24只，两种品系小鼠均各随机分入假手术组（sham组，分别为基因敲除sham组和野生型sham组）和肠缺血再灌注组（IR组，分别为基因敲除I／R组和野生型I／R组），每组12只。麻醉后I／R组小鼠制备肠缺血再灌注致ALI模型，sham组小鼠除不钳夹血管外其余操作同I／R组，待再灌注6h后处死小鼠开胸取肺标本，苏木精-伊红染色后在光学显微镜下观察肺组织病理学改变并行肺组织病理半定量评分，计算肺湿千重比，应用酶联免疫吸附试验检测肺组织肿瘤坏死因子（TNF）-α和白细胞介素（IL）一6水平，应用反转录一聚合酶链反应检测Toll样受体4（TLR4）mRNA表达水平。结果野生型I／R组的肺组织病理半定量评分显著高于野生型sham组（P％0．05），而基因敲除I／R组显著低于野生型I／R组（P〈O．05）。野生型I／R组的肺湿干重比显著高于野生型sham组（P〈O．05），而基因敲除I／R组与基因敲除sham组的差异无统计学意义（P〉O．05）。野生型I／R组肺组织TNF-α和IL-6水平均显著高于野生型sham组（P值均〈0．05），而基因敲除I／R组肺组织TNF-α和IL-6水平显著低于野生型I／R组（P值均〈O．05）。野生型I／R组肺组织TLR4mRNA的表达显著高于野生型sham组（P〈O．05），而基因敲除I／R组肺组织TLR4mRNA的表达显著低于野生型I／R组（P〈0．05）。结论MyD88基因敲除可明显减轻小鼠肠缺血再灌注后的ALI，减轻肺水肿和肺血管通透性，下调肺组织TLR4mRNA表达和TNF_a、IL-6水平。

[Abstract] Objective To investigate the effect of myeloid differentiation factor 88 （MyD88） on acute lung injury （ALl） induced by intestinal ischemia-reperfusion （I/R） in mice. Methods Twenty-four wild type 057BL/6J mice were randomly divided into 2 groups （n = 12 each） ： sham operation group and intestinal I/R group. Twenty- four male MyD88 gene knock-out （MyD88-j- ） mice （aged 6-8 weeks） were also randomly divided into 2 groups （n = 12 each）： sham operation group and intestinal I/R group. Intestinal I/R injury was induced by clamping the superior mesenteric artery for 45 min and the mice were sacrificed at 6 h after reperfusion. The lungs were immediately moved and dyed by Hematoxylin-Eosin （H-E） staining for microscopic examination and pathological semiquantitative analysis. The ratio of wet to dry （W/D） lung weight was detected. The levels of tumor necrosis facotr-αlpha （TNF-cc） and interleukin-6 （IL-6） were measured by enzyme-linked immunosorbent assay and Toll-like receptor 4 （TLR4） mRNA expression in the lung tissue was detected by reverse transcriptase polymerase chain reaction. Results The score of pathological semiquantitative assessment of lung tissue in 057BL/6J I/R group was significantly higher than that in 057BL/6J sham operation group （ P〈0.05）, while the score in MyD88-/- I/R group was significantly lower than that in 057BL/6J I/R group （P〈0.05）. The W/D lung weight ratio in 057BL/6J I/R group was significantly higher than that in 057BL/6J sham operation group （P〈0.05）, but there was not significant difference in the W/D lung weight ratio between MyD88＋ I/R group and MyD88-/- sham operation group （P〈0.05）. The levels of TNF-α and IL-6 in 057BL/6J I/R group were significantly higher than those inC57BL/6J sham operation group （both P〈0.05）, while TNF-α and IL-6 levels in MyD88-/- I/R group were significantly lower than those in 057BL/6J I/R group （both P〈0.05）. The expression of TLR4 mRNA in C57BL/6J I/R group was significantly higher than that in 057BL/6J sham operation group （P〈0.05）, while TLR4 mRNA level in MyD88-/- I/R group were significantly lower than that in C57BL/6J I/R group （P〈0.05）. Conclusion The ALl induced by intestinal ischemia reperfusion, pulmonary edema and vasopermeability can be obviously decreased after MyD88 gene knock-out in mice, which may be achieved through decreasing TLR4 mRNA expression and levels of TNF-α and IL-6 in the lung. （Shanghai Med J, 2013, 36： 837-840）