Dynamic changes of regulatory T cells in the process of radiation-induced pulmonary fibrosis in mice
WANG Cai-hong1,2, PAN Xiao-xian1,2, CHEN Jin-mei2,3,4, HUANG Fei3,4,5, WU Jian-dong2, HONG Jin-sheng2,3,4
(1. The First Clinical College, Fujian Medical University, Fuzhou Fujian 350005; 2. Department of Radiotherapy, the First Affiliated Hospital of Fujian Medical University, Fuzhou Fujian 350005; 3. Key Laboratory of Radiation Biology, Fujian Higher Education, Fuzhou Fujian 350005; 4. Fujian Key Laboratory of Individualized Active Immunotherapy,Fuzhou Fujian 350005; 5. Central Laboratory, the First Affiliated Hospital of Fujian Medical University, Fuzhou Fujian 350005,China)
Abstract:[Abstract]Objective: To investigate the dynamic changes of regulatory T cells(Treg cells) in the progress of radiationinduced pulmonary fibrosis. Methods: Eighty eightweekold 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 Xray delivered by a liner accelerator to establish the mice model of radiationinduced 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 irradiationinduced pulmonary fibrosis in mice, and the overall presented a trend of increasing first and then decreasing.
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