肌球蛋白轻链激酶在急性肺损伤模型的表达及意义

Expression of myosin light chain kinase in acute lung injury

目的通过建立细菌脂多糖(LPS)诱导的小鼠肺损伤模型,并观察其炎症程度和肌球蛋白轻链激酶(MLCK)的表达,探讨MLCK在急性肺损伤发病机制中的作用。方法20只BALB/c雌性小鼠,按随机数字表法分为LPS组(n=10)和生理盐水对照组(n=10),LPS组鼻内注入30μL含20μg LPS的生理盐水,对照组仅用生理盐水。比较两组的病理学、湿干比重、肺泡灌洗液(BALF)总细胞计数的不同,并采用免疫组化法观察MLCK在肺组织的表达,用RT-PCR法检测肺组织中MLCK mRNA的表达。结果与对照组比较,LPS组表现为明显的肺充血、水肿、中性粒细胞浸润,肺含水量增加,BALF细胞总数含量增高(P<0.05或P<0.01);免疫组化结果显示,LPS组MLCK表达较对照组更明显;RT-PCR结果显示LPS组MLCK mRNA吸光度值较对照组高。结论LPS能导致急性肺损伤,MLCK活性上调在其发病机制中起一定作用。

Objective To study the inflammation and expression of myosin light chain kinase（MLCK） through establishing acute lung injury animal model of mice induced by lipopolysacchride（LPS） , and approach the role of MLCK in the mechanism of acute lung injury. Methods Twenty female BALB/c mice were randomly divided into LPS group（ n = 10） and control group（ n = 10）. The BALB/c mice of LPS and control groups were induced by 30 μL 0. 9% NaCl via intranasal instillation, while only LPS group was treated with LPS （20 μg/each mice）. The pathology, wet/dry lung weight ratio and the total cell quantitation in bronchoalveolar lavage fluid（BALF） were compared between these two groups. Furthermore, immunohistochemistry assays were used to determine the status of MLCK expression in the lung. And RT-PCR was adopted to determine the status of MLCKmRNA in the lung. Results Compared with the control group, the LPS group showed more serious pulmonary hemorrhage, edema and infiltration of neutrophils, significantly increased water content in the lungs and total cell quantitation in BALF （ P 〈 0.05 or P 〈 0.01 ）. It was suggested by immunohistochemistry assays that MLCK was more significantly expressed in the LPS group than the control group, and it was revealed by RT-PCR that the absorbance of MLCK mRNA in the lung of LPS group was significantly higher than that of the control group. Conclusion Acute lung injury was found in mice treated with lipopolysacchride, and the upregulation of MLCK activity may play a possible role in the pathogenesis of acute lung injury.