Enterovirus 71 Infection And Study The Possible Mechanism Of Injury In Mouse Brain Mitochondria

Development of a Mouse Model for EV71Infection and Mitoehondrial Injury Detection of brainObjective To establish a mouse model for EV71infection and detect mitoehondrial injury of the brain at different times after infectuon..Methods120one day old ICR mice were divided into infected group and control group. Each group included60mice. The mice of infected group were disposed by intraperitoneal injection of EV71and the mice of control group were injected a same volume of DMEM. Symptoms in mice were observed after inoculated, and euthanatized the mice by diethyl ether anesthesia at1,3,5,7,10and14days after inoculation and separated brain, respectively. Fluorescence quantitative RT-PCR technique was used to detect the viral load of EV71in the brain. Mitochondrial membrane potential was evaluated by flow cytometric analysis. Immune histochemical method was used to detect the expression of cytochrome C in the cytoplasm of brain cells. Pathological changes on brain tissues were observed through hematoxylin-eosin staining and ultrasture of brain cells’ mitochondria were observed by electron microscope.Results Symptoms such as arching back, less move and hind limb paralysis occurred in the mice of infected group after3days, followed by weight dropping dramatically at day5. There were significantly higher levels of viral load in mice brain at3days and7days than5days and10days after infection(p<0.01). And EV71RNA could not be detected at1day,14days after infection and in control group. There were inflammatory cells infiltration around brain vessels at3days and microglial nodules in brain at5days after infection. Mice brain mitochondrial membrane potential of infected group at3days and5days were decreased significantly as compared to control group(p<0.01). However, no significant difference was observed in mitochondrial membrane potential in infected group at1,7,10and14days as compared to control group(p>0.05). The mice of infected group at3,5,7days had significantly higher positive rate of cytochrome C as compared to control group. The control group mice had a complete structure of mitochondria membranes and the mitochondrial cristae were clearly discenible in brain cells. The brain cells showed showed mitochondria swelling with disappearance of mitochondrial crista. At10days after infection, mitochondrial ultrastructurealmost mainly restored to normal.Conclusion The EV71infection mouse model was established successfully and severe inflammation was occurred in brain after EV71infection; The decrease of mitochondrial membrane potential and mitochondria ultrastructure changes were occured in the brain at the early phase of EV71infection, which led to mitochondrial injury. The mitochondrial membrane potential and the mitochondria ultrastructure showed a trend of recovery during later stage of EV71infection. Study on the Potential Mechanisms of Brain Mitochondria Injury of EV71Infected mouseObjective To investigate the potential mechanisms of brain mitochondria injury of EV71infected mouse.Methods The levels of inflammatory factors and oxidative stress factors in mice brain were assessed at1,3,5,7,10and14days after EV71infection. Inflammatory factors in brain including interleukin(IL)-6and IL-1β were assessed by enzyme linked immunosorbent assay(ELISA). Oxidative stress factors in brain including malondialdeh-yde(MDA) and nitric oxide(NO) were assessed by colorimetry method and nitrate reduction method, and analyzed the correlation between them and mitochondrial membrane potential to find a potential mechanism of brain mitochondria injury of EV71infection.Results The concentration of IL-1β were significantly higher in infected group at3,5and7days as compared to control group(p<0.01), and it had negative correlation with brain mitochondrial membrane potentia.The concentration of IL-1β had positive correlation with the concentration of MDA and NO in the brain of EV71infected mice. The concentration of IL-6were significantly higher in infected group at3,5,7and10days as compared to control group. However, there was no correlation between IL-6concentration and brain mitochondrial membrane potentia. The level of brain MDA was significantly higher in infected group at3,5and7days as compared to control group(p<0.01). The concentration of brain NO was also significantly higher in infected group at3days and5days postinfection. The concentration of MDA and NO had negative correlation with brain mitochondrial membrane potentia. Conclusion IL-1β could be lead to brain mitochondria injury through aggravating the oxidative stress in the mitochondrial. Oxidative stress was an important causation of EV71infected mice brain mitochondrial injury. And MDA and No play crucial roles in brain oxidative stress injury.