Waerhaug Kristine, Kuklin Vladimir N, Kirov Mikhail Y, Sovershaev Mikhail A, Langbakk Bodil, Ingebretsen Ole C, Ytrehus Kirsti, Bjertnaes Lars J
Department of Anesthesiology, Institute of Clinical Medicine, Faculty of Medicine, University of Tromsø, Norway.
Crit Care. 2008;12(4):R104. doi: 10.1186/cc6985. Epub 2008 Aug 15.
Acute lung injury often complicates severe sepsis. In gram-negative sepsis, bacterial endotoxin activates both coagulation and inflammation. Enhanced lung vascular pressures and permeability, increased extravascular lung water content and deteriorated gas exchange characterize ovine endotoxin-induced lung injury, a frequently used model of acute lung injury. Recombinant human activated protein C (rhAPC), with its anticoagulant, anti-inflammatory, fibrinolytic and antiapoptotic effects, reportedly reduces the respirator-dependent days and the mortality of patients with severe sepsis. We speculate whether rhAPC antagonizes endotoxin-induced lung injury in sheep.
Two groups of sheep were exposed to Escherichia coli endotoxin (lipopolysaccharide) 15 ng/kg/minute intravenously from 0 to 24 hours; one group received only lipopolysaccharide throughout (n = 8), and the other group received lipopolysaccharide in combination with rhAPC 24 microg/kg/hour from 4 to 24 hours (n = 9). In addition, one group received rhAPC as above as the only intervention (n = 4), and four sham-operated sheep were used for determination of the alpha and epsilon isoforms of protein kinase C in pulmonary tissue. Data were assessed by one-way analysis of variance for repeated measurements. Biochemical data were analyzed using Student's t test, or using the Mann-Whitney U test when appropriate.
Infusion of endotoxin caused lung injury, manifested by increments in pulmonary artery pressure, in pulmonary micro-occlusion pressure, in pulmonary vascular downstream resistance, in pulmonary vascular permeability index, in extravascular lung water index and in deterioration of oxygenation that were all attenuated by infusion of rhAPC. Endotoxemia led to changes in inflammation and coagulation, including pulmonary neutrophil accumulation paralleled by increased TNFalpha and decreased protein C and fibrinogen in animal plasma, which all improved following infusion of rhAPC. Moreover, rhAPC prevented the translocation of protein kinase C alpha and epsilon isoforms from the cytosolic fraction of lung tissue extracts.
In awake sheep, rhAPC alleviates endotoxin-induced lung injury--as characterized by improvements of oxygenation, coagulation and inflammation, as well as by reversal of pulmonary hemodynamic and volumetric changes.
急性肺损伤常使严重脓毒症复杂化。在革兰氏阴性菌脓毒症中，细菌内毒素可激活凝血和炎症反应。肺血管压力和通透性增强、血管外肺水含量增加以及气体交换恶化是绵羊内毒素诱导的肺损伤的特征，这是一种常用的急性肺损伤模型。重组人活化蛋白C（rhAPC）具有抗凝、抗炎、纤溶和抗凋亡作用，据报道可减少严重脓毒症患者的机械通气依赖天数和死亡率。我们推测rhAPC是否能拮抗绵羊内毒素诱导的肺损伤。
两组绵羊在0至24小时内静脉注射大肠杆菌内毒素（脂多糖），剂量为15 ng/kg/分钟；一组全程仅接受脂多糖（n = 8），另一组在4至24小时内接受脂多糖联合rhAPC，剂量为24 μg/kg/小时（n = 9）。此外，一组接受上述rhAPC作为唯一干预措施（n = 4），四只假手术绵羊用于测定肺组织中蛋白激酶C的α和ε亚型。数据采用重复测量的单向方差分析进行评估。生化数据采用Student's t检验进行分析，或在适当情况下采用Mann-Whitney U检验。
输注内毒素导致肺损伤，表现为肺动脉压、肺微阻塞压、肺血管下游阻力、肺血管通透性指数、血管外肺水指数增加以及氧合恶化，而输注rhAPC可减轻这些损伤。内毒素血症导致炎症和凝血变化，包括肺中性粒细胞积聚，同时动物血浆中TNFα增加、蛋白C和纤维蛋白原减少，输注rhAPC后这些情况均得到改善。此外，rhAPC可防止蛋白激酶Cα和ε亚型从肺组织提取物的胞质部分移位。
在清醒绵羊中，rhAPC可减轻内毒素诱导的肺损伤，其特征为氧合、凝血和炎症改善，以及肺血流动力学和容量变化的逆转。
