Expression And Significance Of S100A8and S100A9in Cerebral Ischemia And Reperfusion Injury

OBJECTIVE:TLR4-/-（C3H/HeJ）and wild-type C3H/HeN mice were subjected to establish amiddle cerebral artery occlusion model, to observe the changes of the mice neural functionand brain cells form, to detect the brain infarction volume and the expression level ofS100A8and S100A9. Then further discuss the possible mechanism of S100A8,S100A9and TLR4contribute to cerebral ischemia and repurfusion injury, and for seeking a newentry point of prevention of cerebral ischemia-reperfusion injury.METHODS:Adult male TLR4-/-and wild-type(WT) C3H/HeN mice were subjected to1htransient middle cerebral artery occlusion. Mice weight20-25g,3months old, reared inExperimental Animal Central of Tongji Medical College, and allowed free access to foodand water and maintained at constant temperature(24±2°C), relative humidity(60±5%).Two kinds of mice were randomly divided into two groups (Sham and MCAO). Madeneurological deficit score after1h ischemia in MCAO group, at24h after reperfusion,made TTC staining to calculate the volume of cerebral infarction, and observe the cerebralcell morphological changes, as well as the expression level of S100A8and S100A9inprotein and mRNAlevel. Results:The neurological deficit score of WT model group was significantly higher than theTLR4-/-model group (P<0.01). TLR4-/-mice had significantly smaller lesion volumes whencompared to WT mice(P<0.01). We found that HE staining showed the nerve cells in WTmodel group arranged in disorder, some cell vacuolation, the nucleus owned different sizes,some concentrated and even coagulated, the changes of the cerebral tissue of TLR4-/-model group of edema、degeneration and necrosis seemed significantly lighter than the WTmodel group. Through the immunofluorescence detected that the positive cell number ofexpression S100A8and S100A9protein was tiny in WT normal and TLR4-/-normal group,but two normal groups had no significant statistical difference, in the model group thepositive cell number increased significantly (P<0.01), compared with the TLR4-/-modelgroup, the number of positive cells in WT model group was increased significantly(P<0.01). RT-PCR analysis showed that the mRNA expression level of S100A8andS100A9of each model group than normal group were significantly increased (P <0.01),but the S100A8and S100A9mRNA level was lower in TLR4-/-model group than WTmodel group (P <0.05).Conclusion:S100A8and S100A9involved in the early process of cerebral ischemia-reperfusioninjury, and likely as endogenous TLR4ligand activated TLR4signaling pathway tomediated early cerebral ischemia-reperfusion injury.