Spatial Distribution Of Dentin Matrix Protein 1 In The Brain And Its Effect On Secondary Brain Injury After Intracerebral Hemorrhage In Mice

Background: Intracerebral hemorrhage(ICH)is a cerebrovascular disease with high rate of disability and mortality.It is also one of the common causes of permanent disability in adults.The main feature of secondary brain injury after ICH is vasogenic edema caused by blood brain barrier(BBB)dysfunction.Dentin matrix protein 1(DMP1)is closely related to BBB,but its role in ICH is still unclear.Objective: To observe the expression distribution and cell location of DMP1 in the brain of Kunming mice,as well as the expression changes in brain tissue after ICH,to preliminarily explore the effect of DMP1 on secondary brain injury in mice after ICH and its possible mechanism.Methods: Mice were randomly selected from healthy adult male Kunming mice as experimental subjects.A total of 6 experimental groups were designed,sham operation group(Sham),6h post-ICH group,12 h post-ICH group,24 h post-ICH group,72 h post-ICH group,7d post-ICH group(n=6),the last 5 groups were injected with autologous blood into the basal ganglia to establish cerebral hemorrhage model,and the Sham group was given the same amount of normal saline as a control.Immunofluorescence(IF)and Western Blot(WB)were used to detect the expression and distribution of DMP1 in the brain of Kunming mice;Evans Blue(EB)experiment was used to detect the destruction of the blood-brain barrier at each time point;24h after ICH was selected as the experimental standard point in the following part according to the above experimental results.Small interfering RNA targeting DMP1(DMP1 si RNA)was administered at 72 h prior to ICH;HE staining and Nissl staining were used to observe the pathological changes of mouse brain tissue;modified Garcia score and corner turn test were used to evaluate the neurological scores of mice,Brain Water Content(BWC)was measured by the dry and wet method;the EB was used to detect the permeability of the BBB;Transmission electron microscopy(TEM)was used to detect the swelling of astrocytes and the tightness of tight junction;WB was used to detect the protein changes of zonula occludens-1(ZO-1),occludin,and matrix metalloprotein 9(MMP9).Results: DMP1 is widely expressed in normal Kunming mouse brain,including the cerebral cortex,hippocampus,internal capsule,corpus callosum,thalamus,external capsule,caudate nucleus,and is coexpressed with neuron markers(Neuron-specific nuclear protein,Neu N)and astrocyte markers(glial fibrillary acidic protein,GFAP)and vascular endothelial cell marker(von Wille brand factor,v WF).Compared with the sham operation group,the expression of DMP1 protein increased at 6h after ICH and reached a peak at 24h(P<0.05),and gradually decreased with time.After ICH,the neurological function score of the mice was significantly reduced;pathological changes were obvious,with edema around the hematoma of the brain tissue,loose cell arrangement.The administration of DMP1 si RNA can effectively alleviate the destruction of BBB,brain edema after ICH and improve the score of neurological function.In addition,in the ICH model,the expression of ZO-1 and occludin were down-regulated,while the expression of MMP-9 was up-regulated.Administration of DMP1 si RNA can reverse the expression of ZO-1,occludin,and MMP-9.Conclusion: DMP1 is widely distributed in the brain of mice,and its expression increases after ICH.Administration of DMP1 si RNA reduces the secondary brain damage related to ICH.The role of DMP1 in the destruction of BBB after intracerebral hemorrhage may be related to the activation of MMP-9.