| Purpose:Radiation-induced lung injury is the common complication in the radiation therapy of chest tumor and the pretreatment of bone marrow transplantation, It has a serious impact on the effectiveness of radiation therapy and the patients' quality of life,And it can be serious respiratory dysfunction or even death. Theory widely accepted is that many kinds of cells and cell factors all effect on lung injury after irradiation.Transforming growth factor-β1 (TGF-β1) may play a key role. At present, there are no truly effective measures on the prevention of radiation injury. Injury of lungs, particular fibrosis induced by radiation is often irreversible. So, it is extremely necessary for the prevention.The aim of this study was observing the preventive and therapeutic effect of Prednisolone in radioaction injury of lungs.Methods: 45 male New Zealand white rabbits were randomly divided into three groups by random card。They were the blank group (a), the irradiated only group (b) and the combined with irradiation and Prednisolone Group (c), each has 15 New Zealand white rabbits. Group (a) has not given other treatment. Group (b) intraperitoneal injected Sodium Chloride began at the first day of being irradiated , with 0.1 ml / kg / d for 4 weeks. Group (c) intraperitoneal injected Prednisolone began at the first day of irradiation , with 0.4 mg/ kg / d for 4 weeks. Each group was observed general state of health after irradiation. Measured the serum levels of TGF-β1 by ELISA method and CT scanning before irradiation and the 1,3,5 months after irradiated. The animals were killed by broken neck after 1,3,5 months of radiation .The right lungs were removed to give HE staining and immunohistochemical staining to carry out the histological evaluation.Results:1.Observing the breathing, weight, and death of New Zealand rabbits:Animals in group a were weight gain, body fit and good appetite, hair shiny. The animals in group b have different levels of spiritual worse, shortness of breath, decreased activity, diet reductions, the respiratory rate increase , and the fur began shedding within the radiation field after 2 to 3 weeks of irradiation. The animals in group c were the spirit of short-term poor, reduction activities, restaurants reductions after 2 to 3 weeks of irradiation, which was better than in group b.Weight change: 1.5 months after the irradiation, In group b and group c , the body weight of animals was significantly lower than in group a(p<0.001)。The weight of animals in group b was significantly lower than in group c(p<0.001)。The changes of respiratory rate: there was no changes of breathing frequency in group a .But in group b and group c , the respiratory rate markedly accelerated after two weeks of irradiation, and significantly higher than that of group a(p<0.05)。In the same period, the breathing frequency in group b was faster than that in group c(p<0.05)。2. CT scanning performance:Imaging performance of group a had no significant change. One month after irradiation, three New Zealand rabbits in five which accepting CT scan were Flake ground glass-like changes in group b .And in the same period, two in group c. Three months after irradiation, four New Zealand rabbits in five were high-density video Flake in group b. Group c only has two ,and the scope is less than group b. Five months after irradiation, Group b has five New Zealand rabbits with the radiation field of high-density fibrosis lesions, and group c has five with scattered and patchy high-density video, the scope and the degree is less than the same period of group b.3. Pathological changes:3.1 General information:The fur of New Zealand rabbits in the radiation field started falling out and the hair is sparse gradually in three weeks after irradiation, continuing to 20 weeks. One month after irradiation: the tissues of lung of animals in group a, group b, and group c, are powder-white. 3 months after irradiation: the lungs of rabbits in group a were powder-white. In group b, the radiation field was kermesinus and with a little bleeding. In group c , the radiation field was kermesinus and with a little bleeding, which were less than group b . Five months after irradiation: the lungs in group a were powder-white, without special focus. In group b, the lungs were flake white lesions. In group c , the flake white lesions of the lung tissue were less than group b.3.2 light microscopy findings:One month after irradiation, the lung tissue were acute inflammatory response , such as exudation, hemorrhage, edema, alveolar epithelial cells desquamated. The pathological changes of group b were the most Severe in the three groups. Three months after Irradiation, acute inflammation performance disappear, a large number of fibroblast proliferation and the specific performance of mesenchymal cells increased, alveolar wall thickening, fibroblast cells increased, reducing the number of blood vessels. Group b is the most obvious. Five months after Irradiation, pulmonary fibrosis Obviously, the structure disappeared replaced by interstitial collagen fibers and collagen organizations, alveolar space was narrow , capillary wall thickening, Group b is the most obvious.4. Immunohistochemical results:One month, three months, and five months after irradiation, the number of positive cells were significantly higher in radiation only group than the other (P <0.01), especially in the first month .The number of cells in the combined with irradiation and Prednisolone group was between the both side things. But it is still significantly lower than radiation alone group (P <0.01).5.The results of assaying the TGF-β1 protein level :There was no significant difference in group a of TGF-β1 from 1 to 5 months; In the third month after radiation , TGF-β1 protein level in the group b was significantly higher than that in group c (P <0.05), group c was significantly higher than that in group a (P <0.05).In the fifth month after radiation, TGF-β1 protein level in group b was significantly higher than that in group c (P <0.05) ,and in group c was significantly higher than that in group a (P <0.05).Conclusion:1.At the high dose irradiation of the lung of New Zealand rabbit tissue can be successfully established radiation-induced lung injury in animal models. It is feasible and reliable to study the dynamic changes and drug early intervention in clinic of the radiation-induced lung injury.2.Prednisolone can reduce the radiation– induced lung injury and fibrosis by inhibiting the immune and anti-inflammatory effects and inhibiting the expression of TGF-β1.3.Prednisolon can reduce the radiation-induced lung injury in rabbits New Zealand, and has a certain preventive effect.
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