NALP3在低氧肺损伤大鼠肺组织中的表达及意义

Expression and significance of NALP3 in the hypoxic lung lnjury in rats

目的:探讨SD大鼠在急性低氧肺损伤形成过程中N A L P 3炎性体的表达变化及其意义。方法:将40只SD大鼠随机分为4组:正常对照组、模拟海拔5 000 m 1 d组、3 d组、7 d组。分别在进入模拟海拔5 000 m后1、3、7 d取肺组织。血气分析仪检测动脉血气;电子天平称量肺组织湿干重并计算湿/干比值;显微镜下观察肺组织形态结构变化和超微结构变化;免疫组化法检测肺组织NALP3、caspase-1、IL-1β蛋白表达水平;ELISA法检测血清IL-1β水平。结果:肺组织病理炎症评分的等级实验各组均高于对照组(P<0.05),3 d组高于1 d、7 d组(P<0.05);电镜结果显示:实验组肺泡II型上皮细胞内有空泡,肺泡腔内较多巨噬细胞;免疫组化结果显示:NALP3、caspase-1、I L-1β的表达1 d开始增加,3 d达到高峰,7 d下降(P<0.0 5),与肺损伤程度呈正相关(r=0.8 1,P=0.01;r=0.76,P=0.03;r=0.84,P=0.01)。实验各组血清IL-1β水平高于对照组(P<0.05),3 d组高于1 d、7 d组(P<0.05)。结论:低氧急性肺损伤早期,NALP3炎性体被激活,通过caspase-1的活化,下游信号IL-1β成熟释放增加,引发肺损伤,提示NALP3炎性体可能在高原低氧急性肺损伤的发生发展中发挥作用。

Objective： To discuss the expression and significance of NALP3 （NACHT-LRR-PYD- containing protein3） inflammasome in SD rats of acute lung injury in simulated hypoxic environment. Methods： Forty SD rats were randomly divided into 4 groups： control and 1, 3, 7 d groups respectively. The rats kept in hypoxic chamber which simulated the environment of 5 000 m altitude for 1, 3, 7 days. After that, the rats were sacrificed and lung tissues were obtained. Meanwhile we examined the arterial blood-gas, wet/dry mass ratio of lung tissues, and the pathological and ultrastructural changes of lungs were also been detected. At last, the protein expression levels of NALP3, caspase-land IL-1β were analyzed by immunohistochemical method, the serum level of IL-1 βwas tested by ELISA assay Results： The lung inflammation scores in actue injury groups were significantly higher than those in control group （P〈0.05）. The 3 day group was the highest than those in i d, 7 d groups （P〈0.05）. In the electron microscope, there were physalides in cytoplasm of AT II cell in study group, and there were many macrophages in the alveolar cavity were observed. Expressions of NALP3, caspase-1 and IL-1β were increased from the first day at the same time, and reached the peak levels in the third day3 but decreased from the seventh day, those trends were positively correlated with the degree of lung injury. The serum level of IL-1β was higher in study group than that in control group, but the 3d group is the highest in the study group （P〈0.05）. Conclusion： At the early stage of hypoxic acute lung injury3 the NALP3 inflammasome is activated through caspase-1 pathway, and which increased the release of IL-lβ and lead to the pathogensis of lung injur our result suggests that NALP3 inflammasome may play an important role in the occurrence and development of the acute lung injury exposed in high altitude.