Neutrophil Extracellular Traps Release In Acute Lung Injury After Traumatic Brain Injury

Objective:As one of the serious public health problems in the world,traumatic brain injury leads to a large number of deaths and disabilities every year,resulting in a huge social and personal economic burden.Acute lung injury is one of the common complications of traumatic brain injury,which has high morbidity and mortality.The pathogenesis of acute lung injury caused by traumatic brain injury includes the release of cytokines,the production of HMGB1 and the glymphatic system,etc.Furthermore,inflammation is also one of the pathogenesis of acute lung injury.Neutrophils,as the first defensive line of body immunity,play an important role in the inflammatory response.Neutrophil extracellular traps(NETs)are one of the bactericidal methods of neutrophils.They are mainly composed of DNA,neutrophil elastase,myeloperoxidase and histones.It is a kind of reticular complex,which can capture and digest pathogenic microorganisms.However,the NETs are double-edged swords,and excessive NETs harm the body.We explore whether neutrophil extracellular traps are involved in the pathogenesis of secondary acute lung injury after traumatic brain injury,to find a new target for the prevention and treatment of secondary acute lung injury after traumatic brain injury.Methods:Male Sprague-Dawley rats(weight 250-300g)were fed at 25? for 12 hours under a light/dark cycle with sufficient food and water.7%chloral hydrate(0.5ml/100g body weight)was anesthetized by intraperitoneal injection,and the brain injury model was made by fluid percussion injury.Grouping:according to the time after traumatic brain injury,the rats were divided into five groups:5min,30min,1h,6h and 12h group.The sham group underwent the same treatment,including craniotomy but without fluid percussion injury.The blood samples and lung tissue samples of rats in each group were taken to detect the related indexes of lung injury and NETs,including lung wet/dry weight ratio,tissue section morphology,myeloperoxidase content,neutrophil elastase content,histone H3 content and frozen section immunofluorescence examination.And the contents of myeloperoxidase,neutrophil elastase and histone H3 in serum were assayed.Results:The rats in the traumatic brain injury group showed obvious pulmonary edema,destruction of alveolar structure and infiltration of neutrophils and erythrocytes in lung tissue.The contents of myeloperoxidase,neutrophil elastase and histone H3 in serum and lung tissue of rats with traumatic brain injury increased.The immunofluorescence of frozen sections of lung tissue of rats with traumatic brain injury showed that there were markers of NETs.Conclusion:The NETs are involved in the pathogenesis of secondary acute lung injury after traumatic brain injury,which may become a new target for the prevention and treatment of secondary acute lung injury after traumatic brain injury.