| Objective: Exploring the impact of thoracic X-ray irradiation on the gene expression of Foxp3 and TGF-β1 in lung tissues of mice. Analyzing the clinical significance of change of Foxp3 and TGF-β1. Discussing the impact of thoracic X-ray irradiation on pulmonary inflammation and immune microenvironment.Method:8 week-old C57/BL6 female mice were randomly divided into experiment group and control group. Mice in experiment group received 12Gy X-ray thoracic irradiation at energy of 6MV, while mice of control group were placed in the radiation operation room without radiation. Three mice from each group were sacrificed respectively at different time of 1, 6, 12, 24, 72 hours and 2, 4, 8, 24 weeks post irradiation. Right lungs were immediately stored at - 80℃, while left lungs were fixed in 4% paraformaldehyde for 24 hours to make paraffin sections. RT-PCR was used to detect expression of gene Foxp3 and TGF-β1. Western blot was used in the experiment to detect protein Foxp3 and RORγt. Paraffin sections were for pathological examination and immunohistochemical examination of Foxp3 and masson dying for collagenous fiber to judge whether the lungs post irradiation developed pulmonary fibrosis.Results:1. Foxp3 mRNA expression in experiment group dropped after radiation , especially at time of 6h, 24h, 72h, 2w, 4w and 8w post irradiation. Western blotting showed that Foxp3 decreased to some extent in experiment group at time of 6h, 24h, 72h and 8weeks after radiation. Immunohistochemical findings showed Foxp3 expressed in nucleus and cytoplasm, and mainly in lymphocytes. Foxp3 decreased after radiation. The immunohistochemical score of control group was 5.89±1.53 and experiment group 3.48±1.05 with a statistical significance (P < 0.05). Compared with corresponding control group, the trail group had obvious statistic significances at 6h, 24h, 4w post irradiation(P<0.01) and statistically different at 1h, 12h, 24w after radiation(P<0.05).2. TGF-β1 expression increased after radiation especially at time of 6h, 12h, 2w and 4w.3. RORγt expressed in both groups.4. According to masson staining, mice in experiment group at 24 weeks after radiation developed radioactive lung fibrosis.Conclusions:1. Foxp3 of mice in experiment group decreased at mRNA and protein levels, indicating that X-ray irradiation might down-regulate the expression of Foxp3.2. Expression of TGF-β1 in experiment group was higher than that in control group. Masson staining showed that mice in experiment group developed lung fibrosis 24 weeks after irradiation, confirming the relationship between TGF-β1 and lung fibrosis.3. Thoracic X-ray irradiation could down-regulate Foxp3 expression which might be related with radioactive lung injury. TGF-β1 might have some relationship with radioactive lung injury. Mechanism of down-regulating Foxp3 expression maybe resulted from activation of TGF-β1/RORγt signal pathway, which might control the immune environment. |