急性呼吸窘迫综合征发病小鼠细胞外组蛋白对肺内皮细胞的激活作用

Activation of lung endothelial cells by extracellular histone in mice with acute respiratory distress syndrome

目的研究急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)发病小鼠细胞外组蛋白和肺内皮细胞的变化及细胞外组蛋白对肺内皮细胞的激活作用。方法选择健康雄性C67BL/6小鼠30只,吸入不同浓度的盐酸(0.01、0.1、0.3和0.5 mol/L,2 ml/kg),分析盐酸吸入致小鼠急性肺损伤与血浆细胞外组蛋白、肺血管内皮损伤标志物的关系。通过尾静脉注射给予小牛胸腺组蛋白(calf thymus histones,CTH)和抗组蛋白特异抗体分析细胞外组蛋白的致炎作用,检测指标包括肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、可溶性血栓调节素(soluble thrombomodulin,sTM)和肺组织病理改变。通过细胞模型分析细胞外组蛋白对肺内皮细胞的直接激活作用。结果小鼠吸入盐酸后6 h,血浆中组蛋白H4、sTM的水平与吸入盐酸浓度呈正相关(r=0.9180、0.8701,P<0.05)。与对照组比较,0.1 mol/L盐酸组和CTH损伤组血浆中TNF-α、sTM浓度明显升高,差异均有统计学意义(P<0.05)。与0.1 mol/L盐酸组比较,抗H4抗体干预组TNF-α、sTM浓度明显降低,差异均有统计学意义(P<0.05)。0.1 mol/L盐酸组小鼠肺组织内可见大量的炎症细胞浸润,肺血管内皮细胞肿胀,肺泡间隔增宽,肺泡内大量纤维蛋白渗出,小片状或灶状出血;抗H4抗体干预组小鼠肺组织病理损伤改善,炎症细胞浸润、肺水肿和出血减轻。结论细胞外组蛋白是盐酸吸入致小鼠ARDS发病中的重要内源性炎性介质,可直接激活肺内皮细胞而促发炎症反应。

Objective To observe the changes of extracellular histones and pulmonary microvascular endothelial cells,and study the activating role of extracellular histones to pulmonary microvascular endothelial cells in the pathogenesis of acute respiratory distress syndrome(ARDS).Methods The correlation of the severity of acute lung injury with extracellular histones and pulmonary endothelial damage was studied through mice model,and acute lung injury was produced by aspiration of different concentrations of hydrochloric acid(0.01、0.1、0.3 and 0.5 mol/L,2 ml/kg).Tumor necrosis factor-α(TNF-α),soluble thrombomodulin(sTM)and lung pathological change were measured.The pro-inflammatory role of extracellular histones was tested by injecting calf thymus histones(CTH)or specific anti-H4 antibody through tail vein.The direct activating role of extracellular histones to pulmonary microvascular endothelial cells was studied through pulmonary endothelial model.Results The extracellular histones in plasma were increased obviously 6h after aspiration of different concentrations of hydrochloric acid in mice.A positive correlation was seen between extracellular histones and concentrations of aspirated hydrochloric acid(r=0.9180,P<0.05).The sTM in plasma also showed a positive correlation with concentrations of aspirated hydrochloric acid(r=0.8701,P<0.05).Merely administering CTH could not only increase TNF-αand sTM in plasma but also cause obvious lung injury,while specific anti-H4 antibody could relieve the inflammation and lung damage caused by CTH.Extracellular histones could directly damage pulmonary endothelial cells to release sTM in pulmonary endothelial model in vitro,while anti-H4 antibody could protect the endothelial cells.Conclusion Extracellular histones are the key endogenic inflammatory mediators during the pathogenesis of ARDS caused by aspiration of hydrochloric acid,which could promote inflammation by directly activating pulmonary endothelial cells.