Regulatory Mechanism Of Microglia-mediated Neuroinflammation In Sepsis-associated Encephalopathy

ObjectiveSepsis-associated encephalopathy(SAE)is the most common and most serious complication of sepsis,and cognitive impairment in SAE is associated with hippocampal damage.Neuroinflammation is the most important pathological basis of cognitive dysfunction in SAE,and microglial migration plays a crucial role in the occurrence and development of neuroinflammation.Forkhead box protein C1(Foxcl)is a member of the forkhead transcription factor family and is involved in cell migration.However,the mechanism by which Foxc1 plays a role in SAE neuroinflammation remains unclear.The purpose of this paper is to study:①LPS-induced neuroinflammation and apoptosis in microglia;②the effect of Foxc1 on LPS-induced neuroinflammation and neuronal apoptosis;③Foxc1 overexpression on hippocampal inflammation and cognition in SAE mice Molecular mechanisms of dysfunctional effects.Methods①The inflammatory response of microglia was induced by endotoxin(LPS),and Foxcl-overexpressing BV-2 microglia were constructed at the same time;②The mice were infected with adenovirus to prepare Foxc1 knockdown mice;③The cecal ligation was used The SAE model was created by perforation(CLP)surgery;④The water maze test(Morris Water Maze,MWM)test was used to evaluate the changes of cognitive function of mice before and after modeling.⑤Molecular biology experiments were used to detect the expression changes of Foxc1,inflammatory factors,neuronal apoptosis proteins and other related proteins.Results(1)In vitro experiments showed that:①LPS-induced inflammatory response in microglia manifested as increased expression of IL-1βand TNF-α:LPS treatment of microglia resulted in down-regulated expression of Foxcl and IκB-α,and increased expression of p65.Flow cytometry showed that the apoptosis ratio of neurons cultured with LPS-treated microglia supernatant was significantly higher than that of the control group.②Foxcl overexpression inhibited LPS-induced inflammatory response and neuronal apoptosis in microglia,manifested as up-regulation of IκB-α expression,down-regulation of p65 expression,decreased secretion of pro-inflammatory factors IL-1β,TNF-α.The percentage of neuronalapoptosis decreased.③Migration assay results showed that Foxcl overexpression inhibited the migration of microglia,and after siRNA-IκB-αinhibited the expression of IκB-αin microglia,Foxcl overexpression inhibited the migration of microglia and neuronal apoptosis was significantly reversed.(2)In vivo experiments showed that:①CLP surgery can lead to neurocognitive dysfunction in septic mice.Foxcl overexpressed adenovirus infection and CLP surgery did not affect the exercise capacity of mice.One week after CLP surgery,mice showed reduced cognitive ability.It is manifested that the latency of mice to find the platform is prolonged,the number of times of passing through the area where the platform is located and the residence time in the quadrant where the platform is located are reduced;after Foxcl overexpression,the latency of mice is shortened,and the number of times the mouse is located in the area where the platform is located and the residence time in the quadrant where the platform is located increases.②The structure of hippocampus of SAE mice was damaged:HE staining showed that the structure of hippocampus in CLP operation group was disordered,and the cytoplasm of neuron cells increased.③ CLP surgery can lead to an inflammatory response in the hippocampus of mice,and the expressions of Foxcl and IκB-α are down-regulated,and the expressions of p65,Iba-1,IL-1 β and TNF-α are up-regulated.④Foxcl overexpression improved the damage of hippocampal tissue in SAE mice.The hippocampal structure of Foxcl overexpression group became orderly,the cell volume became smaller,and the cytoplasmic edema was improved compared with the CLP group.⑤Foxcl overexpression inhibited the inflammatory response in the hippocampus of SAE mice,the expression of IκB-α was up-regulated,and the expression of p65,IL-1β and TNF-α was down-regulated.⑥Foxcl overexpression inhibited the migration of microglial cells and neuronal apoptosis in the hippocampus of SAE mice:Compared with the CLP group,the Foxcl OE group had down-regulated Iba-1 expression,decreased the number of microglia and decreased neuronal apoptosis.Conclusion Both in vivo and in vitro methods confirm that Foxcl can improve the cognitive dysfunction in SAE mice by regulating the expression of IκB-α protein,inhibiting NF-κB signaling pathway,neuroinflammation and neuronal apoptosis.