Depletion of CD4+T cells improves the damage of the blood-brain barrier in a mouse model of anti-NMDAR encephalitis

QIU Qinjie; LIU Jiaru; JIN Congli; WANG Yan; ZHOU Haihong

doi:10.20227/j.cnki.2096-3610.2026.01.008

Abstract：Objective To investigate the effect of CD4+T cell depletion on blood-brain barrier(BBB)integrity in a mouse model of anti-N-methyl-D-aspartate receptor(NMDAR)encephalitis.Methods Twenty-four 8-week-old female C57BL/6J mice were randomly divided into 4 groups(n=6 per group).The groups were as follows:the normal group(subcutaneously injected with phosphate-buffered saline on the back),the anti-NMDAR encephalitis model group(abbreviated as the model group,subcutaneously injected with GluN1356-385 polypeptide on the back),the anti-NMDAR encephalitis model intervention group(abbreviated as the model intervention group,in which anti-NMDAR encephalitis model mice were intraperitoneally injected with anti-CD4 monoclonal antibodies),and the anti-NMDAR encephalitis model control group(abbreviated as the model control group,in which anti-NMDAR encephalitis model mice were intraperitoneally injected with isotype control antibodies).Cell-based immunofluorescence was used to detect anti-GluN1 subunit antibodies in the serum of model mice to verify the successful establishment of the model.Western blot was employed to detect the expression changes of tight junction proteins zonula occludens-1(ZO-1),Claudin-5,matrix metalloproteinase 9(MMP-9),and the M1 polarization marker protein CD68 of microglia in the brain tissue.Immunofluorescence was used to detect the morphological changes of microglia.The open-field test and the novel object recognition test were used to detect the behavioral changes in mice.Results Compared with the normal mice,the serum anti-GluN1 subunit antibody was positive in the model mice,indicating successful establishment of anti-NMDAR encephalitis model mice.Compared with the normal group,the expression of tight junction proteins ZO-1 and Claudin-5 in the brain tissue of the model group was significantly decreased.In the hippocampus,the number of microglial branches was significantly increased and the branch length was significantly shortened,and the expression of CD68,a marker protein for M1 polarization of microglia,was significantly upregulated(P<0.001 or 0.05).Compared with the model control group,after depleting CD4+T cells in the model intervention group,the motor and anxiety levels of mice were not affected(P>0.05),while the novel object recognition ability was significantly improved(P<0.05).The expression of tight junction proteins ZO-1 and Claudin-5 in the brain tissue was significantly increased(P<0.05),the number of microglial branches was significantly decreased and the branch length was significantly increased(P<0.001),and the expression of CD68,a marker protein for M1 polarization of microglia,was significantly decreased(P<0.01).Conclusion In a mouse model of anti-NMDAR encephalitis,CD4+T cell depletion helps restore BBB tight junction integrity,improves cognitive function,and shifts microglial polarization from the pro-inflammatory M1 phenotype toward anti-inflammatory M2 phenotype.