急性肺损伤大鼠呼吸膜AQP1和AQP5的表达

目的确定水通道蛋白AQP1及AQP5是否在大鼠肺泡毛细血管膜(呼吸膜)表达,进而研究急性肺损伤(ALI)大鼠AQP1和AQP5的表达调节及激素干预的作用。方法采用亲和的抗人AQP1和AQP5抗体,应用免疫组化及免疫电镜的方法研究AQP1及AQP5在呼吸膜的分布。选用肺泡内灌注脂多糖(LPS)制作大鼠ALI动物模型,研究ALI时呼吸膜AQP1及AQP5的变化。结果免疫染色显示AQP1主要表达于正常肺组织的微血管内皮,而AQP5主要表达于肺泡I型上皮细胞。免疫组化分析进一步表明LPS灌注后4h~48h AQP1及AQP5在呼吸膜的表达均下降;AQP1蛋白于LPS灌注后24h及激素干预后有部分恢复(P0.05),而AQP5无这种恢复现象。结论 ALI时AQP1及AQP5在呼吸膜的表达减少,提示ALI时AQP1和AQP5的下降表达可能与其液体转运的异常有关。

Expression of AQP1 and AQP5 is decreased in the alveolar-capillary membrane in rats with acute lung injury

Objective To determine if aquaporin1 (AQP1) and aquaporin5 (AQP5) are expressed in the alveolar-capillary membrane in rats, and to investigate the changes of AQP1 and AQP5 expression in the rat with acute lung injury. Methods The distribution of AQP1 and AQP5 in alveolar capillary membrane was investigated by immunohistochemistry and immunoelectron microscopy with affinity-purified antibodies to human AQP1 and AQP5. The possibility that alveolar capillary membrane AQP1 and AQP5 undergo altered regulation was studied by a rat model established using intra-tracheal instillation of lipopolysaccharide (LPS). Results Immunolabelling showed that AQP1 was stained primarily in the microvascular endothelium of normal lungs, while AQP5 was expressed in type I pneumocytes. Immunohistochemical analysis showed a significant decrease in the expression of AQP1 and AQP5 in injured lungs at 4-48 h after LPS instillation. AQP1 protein was resumed partly at 24 h after LPS instillation and steroid administration, whereas AQP5 was unchanged. Conclusions The decreased expressions of AQP1 and AQP5 in injured lungs suggest that both of them may play a role in abnormal fluid transportation.