The Regulation Of IL-17A On Astrocyte Activation And Act1/IRF-1 Pathway In Development Of POCD

Postoperative cognitive dysfunction(POCD)is the main central nervous system complications after surgery,epically in elder and high critical ill patients.Advanced age and critical surgery are high risk factors of POCD.The pathogenesis of POCD is still confusing.Central inflammatory response is the main features of degenerative diseases which contains multiple sclerosis,Alzheimer disease,Parkinson's disease and POCD.With the elder age and stimulating from peripheral environment,the central nervous system of elder or critical patients were in the lightly chronic inflammatory environment.The operation wound may destroy the inflammatory and immunologic balance of central nervous system.Normally,operation wound may activate the astrocyte,microglia cells and oligodendroglia cells to balance the inflammatory immune systems and protect the neuron.But operation wound in the elder and high critical ill patients may stimulate the inflammatory cascade reaction,the inflammatory cytokines release may develop into continuous inflammatory reaction,and destroy the balance of immune system.It will lead to series of complication such as POCD.Astroglia cells are the most widely distributed gliocyte in mammalian central nervous system,which form the blood brain barrier.The astroglia cells could be activated by the immune cells and inflammatory factors,it is also the source of inflammatory cytokines and chemokine in central nervous system.IL-17 A can mediate inflammatory responses of astrocytes.It has been proved that the IL-17 RA receptor was expressed in the cytomembrane of astroglia cells.IL-17 A can influence the astroglia cells in ischemia,inflammatory and retrogression.The IL-17 RA can express in the astroglia cells of human and murine.Act1/IRF-1 pathway can regulate the inflammatory responses in central inflammatory immune response system.Based on the above,we hypothesized that surgery wound may induce the exogenous IL-17 A act on the IL-17 RA to regulate the astroglia cells activation,stimulate the inflammatory cytokines and chemokine release,produce excessive inflammation,which will result in the POCD.Part 1:The effect of IL-17 A to the Postoperative cognitive function and astrocyte cellsObjective: Observe the IL-17 A expression after TFS(tibial fracture surgery)and effects of IL-17A(Abs)to the astrocyte and postoperative cognitive Method: Mice TFS model was established to stimulate surgery stimulation,observe the change of IL-17 A expression in POCD.Study on the effects of Abs to the inflammation of the central nervous system,astrocytes and postoperative cognitive.Culture the astrocytes in vitro,then observe the effect of different concentration of IL-17 A to the astrocytes.ELISA was used to detected the IL-17 A in the serum and hippocampus.TFC and Y-maze was used to test the cognitive function change.RT-q PCR was used to detect the inflammatory cytokines(Il6,Tnf?,Il1?)and chemokine(Ccl2,Ccl5,Cxcl10)levels and the expression of Gfap gene.Western blot was used to detected the astroglia positive cells expression on CA1 and CA2 area;Immunofluorescence and Western blot to monitor the expression of astrocytes.Results: The IL-17 A expression in the serum and hippocampus was increased after 6,12,24 and 48 hours after TFS.After 12 hours of TFS,the IL-17 A in the peak until after operation 48 hours.Astroglia positive cells expression and activation on CA1 and CA3 increase significantly in the surgery group.inflammatory cytokines(Il6,Tnf?,Il1?)and chemokine(Ccl2,Ccl5,Cxcl10)levels and the expression of Gfap gene in hippocampus also increasing markedly;the freeze reaction time of TFC was decrease and the time of Y-maze run to the safe area was increased.After treated with Abs,the astroglia positive cells expression on CA1 and CA2 area were decreased,the activation of astroglia cells also decrease.The expression of inflammatory cytokines(Il6,Tnf?,Il1?)and chemokine(Ccl2,Ccl5,Cxcl10)levels and the expression of Gfap gene also decrease.the freeze reaction time of TFC was decrease and the time of Y-maze run to the safe area was increased,which shown a dose-effect relationship.Conclusion: surgery may induce the IL-17 A secretion increasing,activating the astrocytes and central inflammatory response,lead to POCD;Oppositely,Abs could reduce the activity of astrocytes,restrain the central inflammatory response,improve postoperative cognitive.Part 2:IL-17 A act astrocyte and control the development of POCD in GFAPTK miceObjective: To observe the position of IL-17 A act astrocyte and control the development of POCD in GFAPTK mice Method: In the GFAPTK F1 gene mice,to complete inhibit/act the astrocyte by the drug of ganciclovir(GCV)and exogenous IL-17 A.All GFAPTK gene mice were randomly assigned the four groups,including the control group,GCV group,IL-17 A group and GCV+IL-17 A group.The GCV group,IL-17 A group and GCV+IL-17 A group build the TFS model.ELISA was used to detected the IL-17 A levels in the serum.TFC and Y-maze was used to test the cognitive function change.Immunofluorescence monitor the expression of astrocytes.Results: Astrocytes were compeletly inhibited by GCV in GFAPTK gene mice.The exogenous IL-17 A can be activate the expression of astrocytes.The IL-17 A expression in the serum was increased after TFS.The freezing reaction time of TFC was decrease and the times of Y-maze run to the safe area was increased.After the GCV preconditioning,astrocytes can not be activated by IL-17 A,The freezing reaction time of TFC was increase and the time of Y-maze run to the safe area was decreased.Conclusion: IL-17 A mainly activate the astrocyte and impact the postoperatively cognition function.Part 3:IL-17 A act Act1/IRF-1 pathway in astrocytes and impair the cogntive funcitonObjective: To observe the mechanism of IL-17 A act Act1/IRF-1 pathway in astrocyte and control the development of POCD.Method: Though these two parts of the animal experiment,Western blotting wasused to detected the levels of Act1,TRAF6,NF-?B(p65)and IRF-1 in the hippocamus of wild mice.Immunofluorescence was monitored the Act1 expression in the hippocamus of GFAPTK gene mice.Results: The levels of Act1,TRAF6,NF-?B(p65)and IRF-1 were increased after TFS in the wild mice;However,the pretreatment of Abs could be decreased the levels of Act1,TRAF6,NF-?B(p65)and IRF-1 proteins.After the astrocytes absolutely inhibited by GCV in the GFAPTK gene mice,the levels of Act1 was decreased,but increased the PSD95;exogenous IL-17 A could be increased the Act1 expression of astrocytes without the GCV in the GFAPTK gene mice,meanwhile,the PSD95 was decreased.Conclusion: IL-17 A mainly activate the Act1/IRF-1 pathway in astrocyte and impact cognition function.