Panos R J, Bak P M, Simonet W S, Rubin J S, Smith L J
Pulmonary Division, Northwestern University Medical School, Chicago, Illinois 60611, USA.
J Clin Invest. 1995 Oct;96(4):2026-33. doi: 10.1172/JCI118250.
Alveolar type II cell proliferation occurs after many forms of lung injury and is thought to play a critical role in alveolar epithelial repair. Keratinocyte growth factor/fibroblast growth factor 7 (KGF) has been shown to promote alveolar type II cell growth in primary culture and alveolar epithelial hyperplasia in vivo. In this study, we used immunohistochemical analysis to determine the intrapulmonary distribution and cellular localization of recombinant human KGF (rhKGF) instilled into the trachea of rats. 6 h after administration, immunoreactive KGF was observed within the lung parenchyma and along alveolar epithelial cell membranes. By 18-24 h, KGF was detected intracellularly in alveolar epithelial cells and intraalveolar macrophages. Immunoreactive KGF was not demonstrable 48 h after delivery or in lung sections from PBS-treated animals. Intratracheal instillation of 5 mg/kg rhKGF stimulated a marked, time-dependent increase in the alveolar type II cell specific labeling index to a maximum level of 33 +/- 3% 48 h after rhKGF administration compared with 1.3 +/- 0.3% after PBS instillation. In addition, this increase in type II cell proliferation in vivo was documented by flow cytometric analysis of isolated type II cells which revealed a nearly fivefold increase in the proportion of cells traversing through the S and G2/M phases of the cell cycle. To test the hypothesis that KGFs effects on type II cells in vivo might affect the response to lung injury, rats were treated with rhKGF and exposed to hyperoxia. Animals that received 1 or 5 mg/kg rhKGF exhibited dramatically reduced mortality (P < 0.001, for both doses). Survival for animals treated with 0.1 mg/kg rhKGF was not significantly different from either untreated rats or animals treated with heat-denatured rhKGF. The lungs of rhKGF-treated animals that survived hyperoxia exposure had minimal hemorrhage and no exudate within the intraalveolar space. These experiments established that intratracheal administration of rhKGF stimulated alveolar type II cell proliferation in vivo and reduced hyperoxia-induced lung injury in rats. Directed delivery of KGF to the lungs may provide a therapeutic strategy to preserve or restore the alveolar epithelium during exposure to hyperoxia or other injurious agents.
在多种形式的肺损伤后会发生肺泡II型细胞增殖，并且被认为在肺泡上皮修复中起关键作用。角质形成细胞生长因子/成纤维细胞生长因子7（KGF）已被证明在原代培养中可促进肺泡II型细胞生长，并在体内促进肺泡上皮增生。在本研究中，我们使用免疫组织化学分析来确定注入大鼠气管的重组人KGF（rhKGF）在肺内的分布和细胞定位。给药后6小时，在肺实质内和沿肺泡上皮细胞膜观察到免疫反应性KGF。到18 - 24小时，在肺泡上皮细胞和肺泡内巨噬细胞内检测到KGF。给药48小时后或在接受PBS处理动物的肺切片中未检测到免疫反应性KGF。气管内注入5mg/kg rhKGF刺激肺泡II型细胞特异性标记指数显著的、时间依赖性增加，在rhKGF给药后48小时达到最高水平33±3%，而注入PBS后为1.3±0.3%。此外，可以通过对分离的II型细胞进行流式细胞术分析来证明体内II型细胞增殖的这种增加，该分析显示穿过细胞周期S期和G2/M期的细胞比例增加了近五倍。为了检验KGF在体内对II型细胞的作用可能影响对肺损伤反应的假设，用rhKGF处理大鼠并使其暴露于高氧环境。接受1或5mg/kg rhKGF的动物死亡率显著降低（两种剂量均P < 0.001）。用0.1mg/kg rhKGF处理的动物的存活率与未处理的大鼠或用热变性rhKGF处理的动物没有显著差异。在高氧暴露后存活的rhKGF处理动物的肺出血极少，肺泡腔内无渗出物。这些实验表明气管内给予rhKGF可刺激体内肺泡II型细胞增殖，并减少大鼠高氧诱导的肺损伤。将KGF定向递送至肺可能提供一种治疗策略，以在暴露于高氧或其他损伤性因素期间保护或恢复肺泡上皮。
