Effect Of Mitochondrial DNA Release On Barrier Function Of Lung Bronchial Epithelial Cells After Hip Fracture In Elderly Patients

BACKGROUND AND SIGNIFICANCEAccording to WHO 2003 guidelines,elderly hip fractures refer to the three categories of femoral neck fractures,intertrochanteric fractures and subtrochanteric fractures of patients aged 65 years or older.Orthopaedic surgeons often refer to hip fractures as the "last fracture of life," because the mortality rate in elderly patients is 15 to 35 percent within a year.Existing studies have shown that complications of pulmonary infection caused by hip fracture in the elderly are the leading cause of death in patients.The traditional view is that long-term bed rest is the direct cause of pulmonary infection.With the progress of surgery,patients’ bed rest time has been greatly shortened.However,studies have shown that the incidence of complications and the resulting mortality of patients with pulmonary infection have not been significantly reduced.The prevention and treatment of pulmonary infection is still a difficult point in the clinical treatment of elderly hip fracture.Recent studies have suggested that the occurrence of pulmonary infection complications after hip fracture in the elderly is related to the disruption of the dynamic balance of anti-inflammatory substances and pro-inflammatory substances in the body’s internal environment and the inducing of systemic inflammatory response.Elderly patients with insufficient compensatory capacity are prone to excessive inflammatory reaction after traumatic injury caused by hip fracture,leading to acute lung tissue injury,barrier function destruction,and susceptibility to pathogenic microorganisms invasion and lung infection.Therefore,it is of great significance to explore the mechanism of lung injury caused by inflammatory reaction after elderly hip fracture and further explore effective target therapy for reducing the incidence of pulmonary infection complications and improving the survival rate of patients with elderly hip fracture.Objective:The purpose of this study was to investigate the mechanism by which the body releases mtDNA to trigger an inflammatory pathway that affects lung bronchial epithelial cells(16-HBE)to destroy the airway barrier after hip fracture.Methods:the extraction and purification of mitochondrial DNA mixture concentration gradient,and intervene in the 16 HBE-24 hours after harvest each cell,CCK8 experiment tests each cell vitality,by immunofluorescence barrier function to each cell connection protein response,by western blot test 16 HBE connection protein Ecalcium adhesion protein expression,by western blot test 16 HBE cells TLR9,NFkB p65 protein expression,by PCR detection of intracellular TLR9 mRNA expression.According to the comprehensive analysis of the above results,the final conclusion is drawn.Results:After the intervention of mitochondrial DNA,the viability of 16-HBE cells was not significantly affected.The expression of junction protein E-cadherin was decreased in 16-HBE cells.The connections of 16-HBE cells became looser than before,and the connections were interrupted at several places.The expression of TLR9 and NF-kB p65 protein in 16-HBE cells increased.TLR9 mRNA expression was increased in 16-HBE cells.Conclusion:1.Mitochondrial DNA can disrupt cell barrier function by interfering with the level of 16-HBE E-cadherin2.Mitochondrial DNA concentration was positively correlated with the expression of inflammatory response pathway protein TLR9.3.Whether mitochondrial DNA concentration is correlated with the expression of the inflammatory response pathway protein NF-kB p65 still needs further study.