Protective effects of theaflavins on radiation injury of thymus

HAN Xiao-dan; ZHANG Jun-ling; XUE Xiao-lei; ZHAO Yu; FAN Sai-jun

doi:10.11958/20170481

Abstract：Objective To investigate the protective effect of theaflavins on thymus injury caused by total body irradiation (TBI).Methods Twenty-five C57BL/6 mice were randomly divided into 5 groups:control group,4 Gy TBI group,4 Gy TBI + 25 mg/kg theaflavins group,4 Gy TBI + 50 mg/kg theaflavins group and 4 Gy TBI + 100 mg/kg theaflavins group.Thymus index and total number of thymocytes were detected at the 14th d post-irradiation to determine the optimal dose of theaflavins.According to this optimal dose,32 C57BL/6 mice were randomly divided into 4 groups:control group,theaflavins group,4 Gy TBI group and 4 Gy TBI + theaflavins group.Thymus histomorphology,CD4CD8 T cell subsets,and reactive oxygen species (ROS) in thymocytes were examined at the 14th d post-irradiation.Results The irradiated thymus exhibited decreased thymus index and total number of thymocytes (P ＜ 0.05),aberrant histomorphology and T cell subsets (P ＜ 0.05),and increased ROS level in thymocytes (P ＜ 0.05).Compared with 4 Gy TBI group,the thymus index and total number of thymocytes were significantly increased in 4 Gy TBI + 50 mg/kg theaflavins group (P ＜ 0.05).The total number of thymocytes was significantly higher in 4 Gy TBI + 50 mg/kg theaflavins group than that in 4 Gy TBI + 25 mg/kg theaflavins group (P ＜ 0.05).Therefore,50 mg/kg theaflavins was chosen as the optimal dose for subsequent experiments.Moreover,the aberrant histomorphology of irradiated thymus was alleviated by theaflavins.A decline in the percentage of CD4-CD8-T cells and an elevation of CD4+CD8-and CD4+CD8+ T cells were found in irradiated mice administered with theaflavins (P ＜ 0.05).Compared with 4 Gy TBI group,the ROS level was significantly decreased in 4 Gy TBI + theaflavins group (P ＜ 0.05).Conclusion Theaflavins exhibits a protective effect on radiation-induced thymus injury.