The Role And Mechanism Of Cathepsin Expression In Mononuclear Cells In The Process Of Inflammatory Injury After Intracerebral Hemorrhage

Objective: Cerebral hemorrhage refers to primary non-traumatic intracerebral hemorrhage,accounting for 10-15% of all stroke,and the mortality rate in acute phase is as high as 30-40%.However,only 10% to 20% of the dead cells in brain tissue after intracerebral hemorrhage come from the direct injury of hematoma.Most of the cell death is caused by inflammatory and apoptotic reactions secondary to intracerebral hemorrhage.Secondary brain injury after cerebral hemorrhage is mainly caused by hematoma occupancy and compression effect,brain edema,destruction of blood-brain barrier,and a series of inflammatory reactions.It has been found that cathepsin B and D participate in inflammation after cerebral hemorrhage,but the specific mechanism is not clear.Moreover,peripheral blood mononuclear cells enter brain tissue after cerebral hemorrhage and participate in inflammation of brain tissue.Our study focused on mouse peripheral blood mononuclear cells to investigate the relationship between the expression level of cathepsin in peripheral blood mononuclear cells and inflammatory injury after intracerebral hemorrhage.Methods: 1.A mouse model of cerebral hemorrhage was established by injecting fresh autologous arterial blood.Peripheral blood of healthy control group and mice at different time points after intracerebral hemorrhage was collected by eyeball extirpating.Mononuclear cells were separated from fresh anticoagulant blood samples by density gradient centrifugation and stored at-80℃ rapidly.Total RNA and protein were extracted from mononuclear cells,and the expression level of cathepsin B and D were detected by real-time quantitative fluorescence-polymerase chain reaction(RT-PCR)and Western blot.2.The expression of cathepsin B and D was inhibited by Ca-074 me and Pepstatin A,respectively.And the inhibition effect was verified by RT-PCR and Western blot.The neurological function of mice was assessed by the 28-point neurological deficit scale,the water content in brain tissue was measured by dry-wet weight method,the damage degree of blood-brain barrier was measured by intravenous injection of Evans blue,and the hematoma volume was measured by hemoglobin content measurement.Result: 1.Compared with the normal control group,the expression of cathepsin B and D in peripheral blood mononuclear cells of intracerebral hemorrhage mice increased,and the level of cathepsin B and D reached the peak one day after cerebral hemorrhage.2.The expression of cathepsin B and D was effectively inhibited by intraperitoneal injection of Ca-074 me and Pepstatin A respectively.After cathepsin B and D were inhibited,the neurological deficit score of mice decreased,the water content of brain tissue decreased,the damage of blood-brain barrier was also significantly reduced,and the absorption rate of hematoma was accelerated.Conclusion: 1.The expression of cathepsin B and D in peripheral blood mononuclear cells increased after intracerebral hemorrhage.2.Inhibiting the expression of cathepsin B and D in peripheral blood mononuclear cells can alleviate brain injury after intracerebral hemorrhage.