调节性T细胞在小鼠放射性肺纤维化进程中的动态变化

Dynamic changes of regulatory T cells in the process of radiation-induced pulmonary fibrosis in mice

目的:研究调节性T细胞(Treg细胞)在放射性肺纤维化进程中的动态变化。方法:80只8周龄雌性C57BL/6小鼠随机分成对照组和照射组,每组40只。用15 Gy 6 MV X线单次照射小鼠胸部构建放射性肺纤维化模型。分别于照射后2天、17天、3个月和5个月取小鼠外周血、肺组织、脾脏。用HE染色和Masson染色评估小鼠肺组织的病理情况;用流式细胞仪检测各时间点外周血、肺和脾脏中Treg/CD4+T细胞的比例;采用2×4析因设计方差分析比较是否照射及各组照射后不同时间点Treg/CD4+T细胞比例的差异。结果:照射后2天、17天,照射组小鼠肺组织出现炎性病理特征;照射后5个月,小鼠的肺泡间隔可见大量胶原沉积,照射组肺组织的胶原容积分数明显高于对照组(P<0.01)。照射后2天、17天,照射组小鼠外周血、肺组织和脾脏中Treg细胞比例均明显高于对照组(P<0.01);照射后3个月,小鼠外周血、肺组织和脾脏中Treg细胞比例较照射后17天明显下降(P<0.01);照射后5个月外周血和肺组织中的Treg细胞比例下降至对照组水平,脾脏中的Treg细胞比例则明显低于照射后3个月和对照组(P均<0.01)。对照组各时间点间无显著差异(P>0.05)。结论:Treg细胞在小鼠放射性肺纤维化进程中发生着动态的变化,总体表现出先升高后下降的趋势。

Objective:To investigate the dynamic changes of regulatory T cells(Treg cells)in the progress of radiation-induced pulmonary fibrosis.Methods:Eighty eight-week-old female C57BL/6 mice were randomly divided into control group and irradiation group,forty mice in each group.Mice thoraxes were irradiated with a single dose of 15 Gy 6 MV X-ray delivered by a liner accelerator to establish the mice model of radiation-induced pulmonary fibrosis.The peripheral blood,lungs and spleens of mice were separated on Day 2,Day 17 and Month 3,Month 5 after irradiation.Lungs in irradiation group and control group were subjected to paraffin section,HE staining and Masson staining were performed to analyze pathological changes.The proportion of Treg cells in CD4+T cells in peripheral blood,lungs and spleens was detected by flow cytometry at each time;Using 2×4 factorial design analysis of variance,we detected the differences in the proportion of Treg cells at different time points after irradiation with or without irradiation.Results:The inflammatory pathological characteristics in lungs of irradiation group were observed on the Day 2 and Day 17 after irradiation;on the Month 5 after irradiation,a large amount of collagen deposition was observed in the alveolar space of the irradiated group,the collagen volume fraction in lungs of irradiation group was significantly higher than that of control group(P<0.01).On the Day 2 and Day 17 after irradiation,the proportion of Treg cells in the peripheral blood,lungs and spleens of irradiated group was significantly higher than that of control group(P<0.01);on the Month 3 after irradiation,the proportion of Treg cells in peripheral blood,lungs and spleen of irradiation group gradually decreased(P<0.01);on the Month 5 after irradiation,the proportion of Treg cells in peripheral blood,lungs of irradiated group decreased to the level of control group,while decreased to less than control group in spleen(P<0.01).There was no significance difference between the control group at each time(P>0.05).Conclusion:Treg cells showed dynamic pattern change in the progress of irradiation-induced pulmonary fibrosis in mice,and the overall presented a trend of increasing first and then decreasing.