急性肺损伤小鼠外周血树突状细胞数量及功能状态的变化

Changes in the number and function of peripheral blood dendritic cells in mice with acute lung injury

目的探讨急性肺损伤（ALI）小鼠外周血树突状细胞（DC）数量及功能状态的变化。方法雄性SPF级C57BL／6小鼠36只，6～8周龄，体重18～22g，采用随机数字表法，将小鼠分为2组（n=18）：对照组（c组）和ALI组。Au组气管内注射脂多糖2mg／kg，以制备ALI模型，C组注入等容量的PBS。于注入LPS或PBS后6、12和24h（T1-T3）时随机取6只小鼠，麻醉后开胸取右心室血样，采用流式细胞仪检测外周血DC数量及DC表达CD80、MHCII的水平；随后处死小鼠，取肺组织，计算湿重／体重（WW／BW）比，光镜下观察病理学结果，行肺损伤评分，采用ELISA法检测肺组织IL-6含量。结果ALI组可见肺泡间隔增宽、充血、出血及大量炎性细胞浸润等病理改变。与C组比较，ALI组各时点肺组织WW／BW比、IL-6含量、肺损伤评分升高，T1时外周血DC数量减少，L时增多，T2、T3时DC表达MHCⅡ水平上调（P〈0．05）。与T1时比较，Au组T2时肺组织IL-6含量升高，T2、T3时外周血DC数量增多，DC表达MHCⅡ水平上调（P〈0．05）；与T2时比较，ALI组L时外周血DC数量增多（P〈0．05）；2组各时点外周血DC表达CD80水平差异无统计学意义（P〉0．05）。结论ALI小鼠外周血DC数量早期减少，随后逐渐增多，功能呈渐成熟状态。

Objective To investigate the changes in the number and function of peripheral blood dendritic cells （DCs） in mice with lipopolysaecharide （LPS）-induced acute lung injury （ALI）. Methods Thirty-six SPF C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were randomly divided into 2 groups （ n = 18 each） ： control group and ALI group. ALI was induced by intra-tracheal injection of LPS 2 mg/kg in 30 μl of PBS in group ALI, while group C received the equal volume of PBS. Six mice were chosen at 6, 12 and 24 h after LPS or PBS admin- istration （T1-3） and anesthetized. The chest was opened and venous blood samples were collected from the fight ventricle for measurement of the number of DCs and the phenotype of DCs （CD80, MHC Ⅱ ） in the peripheral blood by flow cytometry. The mice were then sacrificed and lungs were removed for microscopic examination and for determination of IL-6 content in lung tissues （by ELISA）. The pathological changes of the lung were scored. Wet lung weight/body weight ratio was calculated. Results Microscopic examination showed widened alveolar sep-turn, congestion, bleeding and massive inflammatory cell infiltration in ALI group. Compared with group C, wet lung weight/body weight ratio, IL-6 content and lung injury scores were significantly increased at each time point, the number of peripheral blood DCs was decreased at T1 , while enlarged at T3, and the expression of MHC Ⅱ was up-regulated at T2,3 in group ALI（ P 〈 0.05）. IL-6 content was significantly higher at T2, and the number of pe- ripheral blood DCs was larger and the expression of MHC Ⅱ was up-regulated at T2,3 than at T1 in group ALI（ P 〈 0.05）. The number of peripheral blood DCs was significantly larger at T3 than at T2 in group ALl （ P 〈 0.05）. There was no significant change in CD50 expression at each time point between the two groups （P 〉 0,05）. Conclusion The number of peripheral blood DCs is decreased at the early period and then increased gradually and the function becomes gradually mature.