Protection of CpG ODN 1826 against radiation pulmonary fibrosis in rats

Objective To explore the protectional function of CpG ODN 1826 against radiation pulmonary fibrosis in rats.Methods The rat left lung was exposed to 20 Gy of 6 MV X-rays for establishing a radiation pulmonary fibrosis model.SD rats were randomly divided into control group,irradiated group and intervention group,with 30 rats in each group.CpG ODN 1826 was intraperitoneally injected into rats at 0,1,2,5 and 7 d post-irradiation.The rats were terminated at 5,15,30 and 90 d post-irradiation,and the lung indexes were recorded.Paraffin sections of the radiated lung were conducted with HE staining and Masson staining,the pulmonary fibrosis scores were recorded.The serum concentrations of TGF-β1 and hydroxyproline (Hyp) were measured.Results The radiation pulmonary fibrosis rat model was successfully established.The lung indexes of the control group were lower than those of the irradiated and intervention groups at 5 d post-irradiation (t =3.046,2.252,P ＜ 0.05).The lung indexes of the intervention group were lower than those of the irradiated group (t =4.120,5.226,5.719,P ＜ 0.05).Pulmonary fibrosis scores of intervention group were lower than those of irradiated group (t =3.212,4.959,P ＜ 0.05).The serum concentrations of TGF-β1 of irradiated group were higher than those of the intervention group (t =4.138,5.924,4.138,5.924,P ＜ 0.05).The Hyp in the lung of irradiated group was higher than that of intervention group (t =7.527,8.416,P ＜ 0.05).Conclusions CpG ODN1826 will not worse the radiation pulmonary fibrosis,on the contrary,it could reduce the serum concentrations of TGF-β1 and the lung content of Hyp in radiation pulmonary fibrosis,and protects rat against radiation pulmonary fibrosis. Key words: Unmethylated cytosine-phosphate-guanine ligodeoxynucleotide (CpG ODN) 1826 ;  Radiation pulmonary fibrosis;  Radiation protection