Objective:To explore effect of IgG receptor FcγRⅡB on neuronal injury and imbalance of Th17/Treg in experi-mental autoimmune encephalomyelitis(EAE)model mice.Methods:C57BL/6 mice were randomly divided into control group,EAE group,FcγRⅡB group and EAE+FcγRⅡB group,with 15 mice in each group.EAE model was induced by subcutaneous injection of MOG35-55 peptide and treated with FcγRⅡB lentiviral solution.After modeling was established,body weight of mice was weighed every day,and neurological function was scored for 30 d;after 30 days,mice were sacrificed.HE staining was used to observe patho-logical changes of brain tissue,LFB staining was used to assess structural changes of spinal cord myelin,and immunofluorescence staining was used to detect spinal cord cerebral cortex neuron nuclear antigen(NeuN)and Caspase-3 expressions,TUNEL staining was used to detect apoptosis of neurons,ELISA was used to detect serum IL-6,IL-17,IL-10 and TGF-β levels,flow cytometry was used to analyze proportion of Th17 and Treg cells in spleen,Western blot was used to determine protein expressions of retinoic acid-related orphan receptor γt(RORγt)and Forkhead family transcription factor 3(Foxp3)in spinal cord tissue.Results:Compared with control group,mice in EAE group had decreased body weight,increased neurological function scores,obvious infiltration of inflamma-tory cells in brain tissue,and signs of demyelination in spinal cord,fluorescence expression intensity of NeuN was weakened and fluorescence expression intensity of Caspase-3 was enhanced,there were more TUNEL-positive stained cells,number of apoptotic cells was increased,levels of IL-6 and IL-17 in serum were increased,and levels of IL-10 and TGF-β were decreased,proportion of Th17 cells in spleen was increased,proportion of Treg was decreased,expression of RORγt protein in spinal cord tissue was up-regu-lated while relative expression of Foxp3 protein was down-regulated(P<0.05);compared with EAE group,weight of mice in EAE+FcγRⅡB group was increased,neurological function score was decreased,infiltration of inflammatory cells in brain tissue was reduced,demyelination of spinal cord was improved,fluorescence expression intensity of NeuN was enhanced,and fluorescence expression intensity of Caspase-3 was weakened,there were fewer TUNEL-positive stained cells,number of apoptotic cells was decreased,levels of IL-6 and IL-17 in serum were decreased,while levels of IL-10 and TGF-β were increased,at the same time,proportion of Th17 cells in spleen was decreased and proportion of Treg was increased,expression of RORγt protein in spinal cord tissue was down-regulated,while expression of Foxp3 protein was up-regulated(P<0.05).Conclusion:FcγRⅡB has neuroprotective effect on EAE mice,and can reduce infiltration of inflammatory cells and demyelination in brain tissue,whose mechanism may be related to regulation of cytokine levels and immune balance of Th17/Treg cells.

Objective:To investigate the effect of glucocorticoids on brain injury in rats with Streptococcus pneumoniae(SP)meningitis,as well as the changes of cerebrospinal fluid immunoglobulin levels under this effect.Methods:A total of 40 SD rats were divided into control group,model group,low-dose methylprednisolone sodium succinate group(Low-MSS)and high-dose methylpred-nisolone sodium succinate group(High-MSS)according to random table method,with 10 rats in each group.Except for the control group,SP meningitis models were established in other groups.Rats in Low-MSS group and High-MSS group were injected with methyl-prednisolone sodium succinate by tail vein at doses of 5 mg/kg and 10 mg/kg,respectively,once a day for 21 days.Neurobehavioral scores of rats after modeling were performed by Loeffler method;contents of immunoglobulin IgA,IgM and IgG in cerebrospinal fluid of rats were detected by immunoturbidimetry;levels of inflammatory cytokines TNF-α,IL-6 and IFN-γ in supernatant of rats brain ho-mogenate were determined by ELISA;HE staining was used to detect pathological changes of rats brain tissue;Nissl staining was used to detect the number of neuronal cells in rats brain tissue;TUNEL staining was used to detect the number of apoptotic cells in rats brain tissue;immunofluorescence staining was used to detect expressions of GFAP and S-100b,the marker proteins of rat brain tissue injury.Results:Before SP injection,there was no difference in neurobehavioral scores between control group and model group(P>0.05),at 24 h,48 h and 72 h after SP injection,neurobehavioral scores in model group were significantly lower than those in control group(P<0.05).Compared with control group,contents of IgA,IgM and IgG in cerebrospinal fluid of rats in model group were in-creased,and contents of TNF-α,IL-6 and IFN-γ in supernatant of the brain homogenate were also increased,the tissue was obviously damaged,accompanied by a large number of inflammatory cells infiltration,the number of neuronal cells were decreased,the number of apoptotic cells were increased,and the fluorescence density values of S-100b and GFAP were increased(P<0.05);compared with model group,contents of IgA,IgM and IgG in cerebrospinal fluid of rats in Low-MSS group and High-MSS group were decreased,and contents of TNF-α,IL-6 and IFN-γ in brain homogenate supernatant were also decreased(P<0.05),brain tissue damage was alleviated,inflammatory cell infiltration was significantly reduced,neuronal cells were increased,the number of apoptotic cells were decreased,and the fluorescence density values of S-100b and GFAP were also decreased(P<0.05).In addition,the improvement effect of various indexes and brain tissue damage in High-MSS group was better than that in Low-MSS group,and the difference were statistically signifi-cant(P<0.05).Conclusion:Glucocorticoid methylprednisolone sodium succinate can effectively improve the brain tissue damage in SP meningitis rats,regulate the levels of immunoglobulin IgA,IgM and IgG,and has a protective effect on SP meningitis rats.