摘要：
目的·探讨Toll样受体4(Toll-like receptor 4,TLR4)在脂肪栓塞综合征动物模型病理损伤中的作用.方法·将120只雄性C57BL/6小鼠随机分成10组,设置1组为空白对照组,其余9组经尾静脉依次注射1、2……9μL/g不同剂量的同种异体肾周脂肪,统计各组死亡率,Bliss法计算小鼠脂肪注射的半数致死量(median lethal dose,LD50),建立小鼠脂肪栓塞LD50模型;蛋白质印迹(Western blotting)检测上述建模后存活小鼠的肺组织TLR4蛋白表达量.另将60只雄性C57BL/6小鼠随机分为对照组(尾静脉注射等计量的生理盐水)和实验组(即为2 h、8 h、24 h及48 h组,尾静脉注射LD50脂肪),Western blotting检测注射脂肪后不同时间小鼠肺组织TLR4蛋白表达量.记录20只TLR4基因敲除小鼠(TLR4-/-)注射LD50脂肪后的死亡率,并与60只注射LD50脂肪的野生型小鼠的死亡率进行比较.结果·小鼠脂肪栓塞模型的LD50为(3.93±0.78)μL/g.注射1～7μL/g不同剂量的脂肪后,小鼠的肺组织TLR4蛋白表达量均有所增加(均P=0.000).在小鼠脂肪栓塞LD50模型中,注射LD50脂肪2 h后,TLR4蛋白表达量较对照组有所增加(P=0.005),随后其表达量逐渐降低,在注射后48 h时与对照组间差异无统计学意义.TLR4-/-小鼠注射LD50脂肪后,死亡率低于野生型小鼠(P=0.043).结论·TLR4参与了脂肪栓塞综合征病理损伤过程,TLR4基因敲除可降低脂肪栓塞小鼠的死亡率.TLR4及其介导的非感染性炎症反应可能是脂肪栓塞综合征生化损伤的重要分子机制.阻断由TLR4介导的信号通路的激活可能改善脂肪栓塞综合征的预后,也可为其预防、评估和治疗提供新的依据.%Objective · To investigate the effect of Toll-like receptor 4 (TLR4) in the pathological injury in fat embolism mice model. Methods · One hundred and twenty male C57BL/6 mice were randomly divided into 10 groups. One group was set as blank control group, and others were injected separately with 1, 2…9 μL/g of allogeneic perirenal fat via tail vein, respectively. The mortality of each group was counted, median lethal dose (LD50) of fat injection in mice was calculated by Bliss method, and the fat embolism LD50 mice model was established. The TLR4 protein expression in the pulmonary tissue of surviving mice was detected by Western blotting. Sixty male C57BL/6 mice were randomly divided into the control group (the same dose of saline was given via tail vein) and the experimental groups (group 2 h, group 8 h, group 24 h and group 48 h, the LD50 fat was given via tail vein).The TLR4 protein expression at different time after fat injection was detected by Western blotting. The mortality of 20 TLR4 gene-knockout mice (TLR4-/-mice) was recorded and compared with 60 wild-type mice after LD50 fat injection. Results · The LD50 of fat embolism mice model was (3.93±0.78) μL/g.After the injection of 1-7 μL/g fat, the expressions of TLR4 protein in the pulmonary tissue of all seven groups were significantly increased, compared with the control group (all P=0.000). In the fat embolism LD50 mice model, compared with the control group, the expressions of TLR4 protein in group2 h were significantly increased (P=0.005). Then, expression level of TLR4 protein was gradually reduced after 2 h, and there was no significant difference between the control group and group 48 h. The mortality of TLR4-/- mice injected with LD50 fat was lower than that of wild-type mice (P=0.043).Conclusion · TLR4 protein involves in the pathologic process of fat embolism syndrome. The knockout of TLR4 gene can reduce the mortality of fat embolism mice. TLR4 and its correlated non-infectious inflammatory response may be an important molecular mechanism of biochemical injury in fat embolism syndrome. Blocking the activation of TLR4-mediated signaling pathway can significantly improve the prognosis, which provides new basis for the prevention, evaluation and treatment of fat embolism syndrome.
