Mueller G A, Quinlan W M, Doyle N A, Doerschuk C M
Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University, Indianapolis.
Am J Respir Crit Care Med. 1994 Aug;150(2):455-61. doi: 10.1164/ajrccm.150.2.8049829.
The cytoskeletal proteins, actin and tubulin, are critical in modulating many aspects of the structural, mechanical, and biochemical properties of cells. This study determined if rearrangements of microtubules or filamentous actin were necessary for neutrophil margination within the pulmonary microvasculature or emigration into the alveolar spaces in response to Streptococcus pneumoniae. Microtubule assembly was inhibited using colchicine, and F-actin depolymerization was inhabited using phalloidin. Anesthetized rabbits received an intrabronchial instillation of S. pneumoniae either after intravenous pretreatment with colchicine (1 mg/kg every 2 h) or combined with TRITC-phalloidin (2 microM in instillate). Four hours later, the lungs were fixed and removed. The results show that the intravenous injection of colchicine caused a rapid decrease in circulating neutrophil counts, most likely caused by sequestration within the pulmonary microvasculature, that gradually recovered. In the pneumonic region, colchicine inhibited neutrophil emigration by 74 +/- 5%, but it did not prevent the stimulus-induced increase in margination. Phalloidin inhibited neutrophil emigration by 83 +/- 4%. These studies suggested that microtubule reassembly occurs during neutrophil transit through the normal pulmonary microvasculature and that it is required for migration but not sequestration during pneumonia. Rearrangement of actin filaments in lung cells but not neutrophils are required for neutrophil emigration induced by S. pneumoniae.
细胞骨架蛋白肌动蛋白和微管蛋白在调节细胞的结构、力学及生化特性的诸多方面起着关键作用。本研究确定了微管或丝状肌动蛋白的重排对于嗜中性粒细胞在肺微血管内的边缘化或响应肺炎链球菌而迁移至肺泡腔是否必要。使用秋水仙碱抑制微管组装，使用鬼笔环肽抑制F-肌动蛋白解聚。麻醉的兔子在静脉注射秋水仙碱（每2小时1mg/kg）预处理后或与TRITC-鬼笔环肽（灌洗液中2μM）联合使用后接受支气管内肺炎链球菌滴注。4小时后，将肺固定并取出。结果显示，静脉注射秋水仙碱导致循环嗜中性粒细胞计数迅速下降，这很可能是由肺微血管内的隔离所致，随后逐渐恢复。在肺炎区域，秋水仙碱抑制嗜中性粒细胞迁移74±5%，但并未阻止刺激诱导的边缘化增加。鬼笔环肽抑制嗜中性粒细胞迁移83±4%。这些研究表明，微管重组装发生在嗜中性粒细胞通过正常肺微血管的过程中，并且它是肺炎期间迁移而非隔离所必需的。肺炎链球菌诱导的嗜中性粒细胞迁移需要肺细胞而非嗜中性粒细胞中的肌动蛋白丝重排。
