The Role Of Nrf2-ARE Pathway During Traumatic Brain Injury

BackgroundTraumatic brain injury(TBI)refers specifically to a class of diseases caused by severe traumatic brain injury,with high morbidity,high morbidity and high mortality characteristics,and survivors are left behind The degree of neurological and psychological aspects of dysfunction,to the community and the family has brought a huge economic and spiritual burden.TBI treatment is limited,so far,no drug has been confirmed to have the exact clinical efficacy.Therefore,how to study its pathophysiological mechanism and find the appropriate target has been the hot and difficult of TBI research.Pathological mechanism of TBI found that post-TB neuronal damage mechanisms,including primary and secondary injury.Which occurred in the primary injury at the time of injury,for clinical non-intervention factors.And secondary injury occurred within a few minutes to several days after injury,it is on the basis of primary injury gradually developed pathological changes,is caused by brain injury occurred,the development of important reasons.Therefore,the treatment of secondary brain injury is the key to improving the prognosis of patients.Secondary pathology of secondary injury is complex,including excitatory amino acid toxicity,oxygen free radical damage,inflammatory response and calcium overload.At present,it is thought that neuronal damage caused by ischemic brain injury is similar to cerebral ischemia-reperfusion injury,and the oxygen free radical chain reaction is the core pathological part of neuronal damage.Brain damage,a large number of oxygen free radicals,on the one hand directly to the lipid,protein and DNA and other macromolecules damage to damage the cell membrane and other cell structure,on the one hand by stimulating the expression of cytokines and adhesion molecules,mediated inflammation And immune response,increased brain injury.Oxygen free radicals can also inhibit the mitochondrial function and other indirect pathway to activate the apoptotic signaling pathway,causing apoptosis.These links common law development,a vicious circle,eventually leading to neuronal ischemia and necrosis.Therefore,for the mechanism of oxygen free radicals in secondary brain injury,inhibition of oxidative stress and clear oxygen free radicals may be an important strategy for the treatment of TBI.In view of the characteristics of multi-channel mechanism of oxidative stress-induced injury,it is possible to provide a new direction and strategy for clinical treatment of TBI by looking for an endogenous antioxidant pathway with multi-channel anti-oxidative damage.The current study that the body produces oxidative stress at the same time,the body's endogenous antioxidant system is also activated,thereby inhibiting the damage caused by oxidative stress,so that the body in a state of balance.The Nrf2-ARE pathway is a vital pathway in the endogenous antioxidant system in vivo.A variety of antioxidant enzymes,detoxification enzymes,calcium ion steady state protein and so on contain a common promoter-antioxidant response element(antioxidant response element,ARE).In a variety of transcription factors that bind to ARE,the transcription factor NF-E2 2(Nrf2)is currently thought to play a key role and can be induced by external factors.Nrf2 belongs to the transcription factor CNC alkaline leucine zipper family.In the physiological state,Nrf2 mainly concentrated in the cytoplasm,and cytoplasmic junction protein Keapl combined to form a complex.Keap1 is a negative regulator of Nrf2,which mediates the degradation of Nrf2 ubiquitination by proteasomes,thereby maintaining a low activity physiological state of Nrf2.When oxidative stress or other chemical substances are stimulated,Nrf2 is decoupled from Keap 1 by phosphorylation,enters the nucleus,binds to the ARE sequence of the relevant gene,and induces the regulated target gene to express hemeoxygenase 1(heme(NAD(P)H:quinine oxidoreductasel,NQO1),which protects the body from active substances and some toxic substances.The expression of Nrf2 in brain tissue of mice after cerebral ischemia was increased,while activation of Nrf2-ARE pathway increased glutathione content in brain tissue and reduced ischemic brain injury.In addition,Nrf2-ARE pathway also has a protective effect on cerebral hemorrhage,the mechanism is to inhibit theinflammatory response,reduce apoptosis.The protein levels of Nrf2,HO-1 and NQO1 were higher than those of normal control group after TBI,and the expression of Nrf2,HO-1 and NQOI was higher than that of normal control group at daytime And 72h,but still higher than the normal control group(p<0.01).Immunofluorescence showed that Nrf2 was expressed in the normal brain tissue in the normal control group.The confocal results showed that Nrf2 was mainly located in the cytoplasm of neurons and glial cells.After TBI,the expression of Nrf2 in the injured cortex was significantly increased Highly,confocal results showed that Nrf2 was predominantly located in the nuclei and cytoplasm of neurons and glial cells.The neuroprotective effect of Nrf2-ARE pathway in traumatic brain injury was demonstrated by NITF knockout mice and normal control group,and its protective effect may be through the up-regulation of antioxidant/detoxifying enzyme expression and inhibit oxidative stress injury To achieve.The Nrf2-ARE signaling pathway is an intracellular protective signaling pathway.The study shows that the downstream molecules of this pathway have antioxidant stress,regulate inflammatory injury,antagonize cell apoptosis and alleviate calcium overload.We have demonstrated that the Nrf2-ARE signaling pathway can regulate the multiple pathological damage mechanism after traumatic brain injury,significantly alleviate the degree of secondary brain injury and improve the prognosis of traumatic brain injury.In this study,we investigated the protective effect of Nrf2 signaling pathway on human brain trauma,and evaluated the activation and function of Nrf2-ARE signaling pathway in clinical traumatic brain injury by systematic parameter analysis.Objective:To investigate the dynamic expression and distribution of Nrf2-ARE signaling pathway in human traumatic brain injury,and to explore the relationship between Nrf2-ARE pathway and traumatic brain injury.Method:2014.9-2017.4 Nanjing Drum Tower Hospital established TBI patient database 192 cases.Frontal lobe brain contusion in 79 cases.36 cases of frontal lobe brain contusion patients meet the inclusion criteriaCriteria:(1)the patient sex is not limited,aged 25 to 45 years;(2)patients with brain contusion;(3)patients with surgical indications,conservative treatment of poor results,preoperative confinement to the family to be removed brain tissue contusion,and with family consent;(4)preoperative patients with Glasgow Coma Scale(GCS)<8 points,and acute physiology and chronic health score II(APACHE II)between 15 and 25 points;(5)to exclude open brain injury,excluding trauma after surgery;(6)preoperative exclusion of patients with other neurodegenerative diseases,tumors or infectious diseases;(7)preoperative exclusion of patients with other organ damage,or chronic disease history;(8)preoperative,intraoperative no hypotension,hypoxia occurred According to the patient's condition,the group of 36 patients were treated at different times,including TBI within 3 hours after the operation of 3 patients,3 hours to 6 hours of surgery patients 6,6 to 12 hours surgery patients 5,12 hours to 24(1 day after TBI)hours of operation 4 patients,24 hours to 36 hours of surgery patients 6 people.36 hours to 48 hours of surgery patients 3,48 hours to 72 hours of surgery patients 5,72 hours to 96 hours of surgery patients 4 people.And divided into 8 groups according to different time points of injury,respectively,within 3 hours after injury,3-6 hours after injury group,6-12 hours after injury group,12-24 hours after injury group,24-36 hours after injury Group,26-48 hours after injury,48-72 hours after injury,72-96 hours after injury.The expression of HO-1 and NQO1 protein in Nrf2 and its downstream molecules were detected by RT-PCR.The expression of HO-1 and NQO1 protein in Nrf2 and its downstream molecules were detected by western blot.Histopathological observation:The expression of Nrf2 in TBI was observed by immunohistochemistry.Result:I.The expression of Nrf2,HO-1 and NQO1 protein in the brain tissue of the injured brain increased gradually,and the expression of Nrf2 reached the peak on the third day after injury.The expression of HO-1 and NQO1 was also increased Three days to reach the peak,then began to decline.2.Immunohistochemical results showed that Nrf2 tissue distribution:in the contusion of brain tissue,Nrf2 mainly in glial cells in the expression of neurons will be a small amount of expression.The cells with high Nrf2 content in the slices showed strong positive(brown),and the number of cells expressing Nrf2 was significantly increased after TBI,and the number of positive cells increased gradually with the prolongation of time.The number of positive cells was the highest at the third day after injury,And gradually reduced afterwards.Conclusion:Nrf2 was activated in the early stage of TBI.Nrf2 was mainly expressed in the nucleus and cytoplasm of neurons and glial cells after TBI,and the activated region was consistent with the lesion area after traumatic brain injury.The activation of Nrf2 increased the downstream antioxidant and detoxification enzyme level after TBI,suggesting that the Nrf2-ARE pathway may be involved in the endogenous stress defense mechanism after TBI.