Vam3 And ZZW1 Ameliorate Ionizing Irradiation-Induced Immune System Injury In C57BL/6 Mice

The patients received radiotherapy in clinic and the victims of nuclear accidents might cause different irradiation injuries. Immune system is hypersensitive to irradiation exposure, it is very important to develop novel therapeutic strategies in protection of immune system injury induced by radiation exposure.Our previous works showed that resveratrol had a protective effect on radiation-induced damage of hematopoietic immune system. According to the recent research, Vam3, a dimeric derivative of resveratrol, exhibits antioxidative and anti-inflammatory actions. But the radioprotective effect of Vam3, as a potential radiation protection agent, has not been reported. Melatonin (MT) is a hormone of benzopyrrole secreted from epiphyseal gland and was recently found to be a free radical scavenger and antioxidant. We modified the drug structure of melatonin to synthesize a new chemical compounds called ZZW1, which also has the function of antioxidant, anti-inflammatory and scavenging free radical.The first part of the study aims to observe the protective effect of Vam3 on the injury of irradiation-induced immune cells in C57BL/6 mice. In vitro, Thymus and spleen were isolated sterilely from mice. Single cell suspension was prepared by grinding and filtering thymus as well as spleen. Immune cells were exposed to radiation at a single dose of 1Gy or 4 Gy y-ray from 137Cs after 30 min incubation by vehicle or tested drug, respectively. The immune cells’ viability were measured by bioluminescence; the ROS level were measured by DCFH-DA; y-H2AX were measured by fluorescent antibody labeling; the early apoptosis was detected by FITC-Annexin V and PI labelling using flow cytometry. The results show that Vam3 has protective effects on the acute radiation injury of immune cells on mice, with more efficiency than resveratrol.The second part of the study aims to observe the protective effect of ZZW1, derivative of melatonin, on the injury of irradiation-induced immune system in C57BL/6 mice. The vitro experiments suggests that ZZW1 has protective effects on the acute radiation injury of immune cells in mice, with more efficiency than MT. In vivo experiments, the mice were exposed to a lethal dose (7.2 Gy, for the survival study only) or sublethal dose (6Gy, for other study) of total body irradiation (TBI) and treated with intragastric administration of ZZW1 for 3 days after irradiation exposure. In survival study, Kaplan-Meier analysis was used to evaluate animal survival after exposure to the lethal dose of TBI. The result showed that ZZW1 can improve the survival rate in mice exposed to lethal dose TBI. In the vivo experiments of 6Gy TBI, the mice were divided into 5 groups randomly, there are control group, ZZW1 group, IR group as well as IR+MT group and IR+ZZW1 group. IR+MT group and IR+ZZW1 group were treated with MT 10mg/kg·day and ZZW1 10mg/kg·day, respectively. The treatments began at the day of irradiation, and last for three days. At 7d,14d and 28d after irradiation exposure, thymus and spleen index, apoptosis rate of thymocytes and splenocytes, ROS level, thymus and spleen tissues antioxidant enzyme activity of GPX, SOD and CAT and MDA content were examined. The changes of the lymphocyte phenotypes in thymus and spleen were also analyzed using flow cytometry. The results showed that ZZW1 could ameliorates immune organ damage induced by ionizing radiation, and it also contributes to the recovery of immune function in the short term in mice, with more efficiency than MT.In summary, our studies demonstrate that Vam3 and ZZW1 exhibit the protective effects on immune system damage induced by ionizing radiation, which suggests that Vam3 and ZZW1 may be used as a therapeutic agent. Due to their low toxicity, it deserves a further study for Vam3 and ZZW1 as potential radiation protectants.