Witzenrath Martin, Gutbier Birgitt, Hocke Andreas C, Schmeck Bernd, Hippenstiel Stefan, Berger Katharina, Mitchell Timothy J, de los Toyos Juan R, Rosseau Simone, Suttorp Norbert, Schütte Hartwig
Charité-Universitätsmedizin Berlin, Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Berlin, Germany.
Crit Care Med. 2006 Jul;34(7):1947-54. doi: 10.1097/01.CCM.0000220496.48295.A9.
Acute respiratory failure is a significant complication of severe pneumococcal pneumonia. In a mouse model, we observed early-onset lung microvascular leakage after pulmonary infection with Streptococcus pneumoniae, and we hypothesized that the important virulence factor pneumolysin may be the direct causative agent.
Controlled, in vivo, ex vivo, and in vitro laboratory study.
Laboratory.
Female mice, 8-12 wks old.
Ventilated and blood-free perfused murine lungs were challenged with recombinant pneumolysin via the airways as well as via the vascular bed. In addition, we analyzed the impact of pneumolysin on electrical cell impedance and hydraulic conductivity of human umbilical vein endothelial cell (HUVEC) and alveolar epithelial cell (A549) monolayers.
Aerosolized pneumolysin dose-dependently increased capillary permeability with formation of severe lung edema but did not affect pulmonary vascular resistance. Intravascular pneumolysin caused an impressive dose-dependent increase in pulmonary vascular resistance and in lung microvascular permeability. By immunohistochemistry, pneumolysin was detected mainly in endothelial cells of pulmonary arterial vessels, which concomitantly displayed strong vasoconstriction. Moreover, pneumolysin increased permeability of HUVEC and A549 monolayers. Interestingly, immunofluorescence of endothelial cell monolayers exposed to pneumolysin showed gap formation and moderate stress fiber generation.
Pneumolysin may play a central role for early-onset acute lung injury due to severe pneumococcal pneumonia by causing impairment of pulmonary microvascular barrier function and severe pulmonary hypertension.
急性呼吸衰竭是重症肺炎球菌肺炎的一种重要并发症。在小鼠模型中，我们观察到肺炎链球菌肺部感染后早期出现肺微血管渗漏，我们推测重要的毒力因子肺炎溶血素可能是直接致病因素。
对照的体内、体外和实验室研究。
实验室。
8 - 12周龄雌性小鼠。
对通气且无血灌注的小鼠肺脏经气道以及经血管床用重组肺炎溶血素进行攻击。此外，我们分析了肺炎溶血素对人脐静脉内皮细胞（HUVEC）和肺泡上皮细胞（A549）单层的电阻抗和水力传导率的影响。
雾化的肺炎溶血素剂量依赖性地增加毛细血管通透性并形成严重肺水肿，但不影响肺血管阻力。血管内注射肺炎溶血素导致肺血管阻力和肺微血管通透性显著剂量依赖性增加。通过免疫组织化学检测，肺炎溶血素主要在肺动脉血管内皮细胞中被检测到，这些细胞同时表现出强烈的血管收缩。此外，肺炎溶血素增加了HUVEC和A549单层的通透性。有趣的是，暴露于肺炎溶血素的内皮细胞单层的免疫荧光显示形成间隙并产生中度应力纤维。
肺炎溶血素可能通过导致肺微血管屏障功能受损和严重肺动脉高压，在重症肺炎球菌肺炎所致的早期急性肺损伤中起核心作用。
