Toll样受体4在失血性休克复苏致小鼠急性肺损伤中的作用

Role of Toll-like receptor 4 in acute lung injury induced by hemorrhagic shock and resuscitation in rats

目的探讨Toll样受体4（TLR4）在失血性休克复苏致小鼠急性肺损伤中的作用。方法TLR4基因突变型C3H／HeJ小鼠和野生型C3H／HeN小鼠各24只，两种品系小鼠各随机分为2组：假手术组（S组，n=6）、失血性休克复苏组（HSR组，n=18）制备失血性休克复苏模型，并于复苏后6、24、48h时各取6只小鼠颈动脉放血处死后开胸取肺组织，免疫组织化学法检测p38 MAPK表达水平，酶联免疫吸附法测定白细胞介素（IL）-10和IL-6含量，透射电镜下观察肺组织超微结构。结果与C3H／HeN小鼠比较，C3H／HeJ小鼠复苏后肺组织p38MAPK表达下调，IL-6和IL-10含量降低（P〈0．05或0．01），病理损伤程度减轻。两种品系小鼠中，与S组比较，HSR组复苏后24h时肺组织IL-6和IL-10含量增加，复苏后48h时肺组织IL-6含量增加（P〈0．05或0．01）；C3H／HeN小鼠中，与S组比较，HSR组复苏后6h和24h时肺组织p38MAPK蛋白表达上调，复苏后48h时肺组织IL-10含量增加（P〈0．01）。结论TLR4参与小鼠失血性休克复苏致急性肺损伤的发生，其机制与激活p38 MAPK信号转导通路有关。

Objective To investigate the role of Toll-like receptor 4 （TLR4） in acute lung injury （ALI） induced by hemorrhagic shock and resuscitation （HS-R） in rats. Methods Twenty-four male C3H / HeN mice （ wild-type mice） and 24 male C3 H/HeJ （ containing a point mutation of TLR4） aged 10-12 weeks weighing 20-25 g were used in this study. Each type of animals were randomly divided into 2 groups： group Ⅰ control （C） （ n = 6） ; group Ⅱ HS-R （n = 18）. The animals were anesthetized with chloral hydrate 400 mg/kg, tracheostomized and mechanically ventilated. Right internal carotid artery was cannulated for MAP monitoring. Right femoral artery and tail vein were cannulated for blood-letting and fluid infusion. Hemorrhagic shock （HS） was induced according to the methods described by Ayala and Fan. MAP was reduced to 35-45 mm Hg within 15 min and maintained for 60 min. The animals were then resuscitated for 30 min with blood transfusion and infusion of lactated Ringer＇s solution. Arterial blood samples were obtained at 6, 24 and 48 h （6 animals at each time point） after the end of resuscitation for blood gas analysis in group HS-R. The animals were then sacrificed. The lungs were harvested for determination of the expression of p38 MAPK protein （by immuno-histochemistry） and IL-6 and IL-10 content （by ELISA） in the lungs. Ultrastructure of the lung was examined under electron microscope. Results The p38 MAPK protein expression in the lung was significantly down-regulated and the IL-6 and IL-10 content in the lung were significantly decreased in C3H/HeJ mice as compared with C3H/HeN mice. The lung histologic damage induced by hemorrhagic shock and resuscitation was significantly less severe in C3H/HeJ mice than in C3H/HeN mice. The IL-6 and IL-10 contents and the expression of p38 MAPK protein in the lung tissue were significantly increased at 24 h after hemorrhagic shock and resuscitation and the IL-6 content in the lung were significantly increased at 48 h after HS-R in both C3H/HeN and C3H/HeJ mice. p38 MAPK protein was significantly increased at 6 h and 24 h after HS-R and IL-10 content was significantly increased at 48 h after HS-R in C3H/HeN mice. Conclusion TLR4 is involved in the development of ALl induced by hemorrhagic shock and resuscitation by activating p38 MAPK signal transduction pathway.