Effect Of Costimulatory Molecules B7-H4 On T Lymphocyte Subsets In Non-obese Diabetic Mice Model Of Sj(?)gren’s Syndrome

Objective To investigate the effect of co-stimulatory molecule B7-H4 on the regulation of T cell subsets in NOD mice induced by Sj?gren’s syndrome(SS).Methods NOD mice were randomly divided into baseline group,normal saline(NS)group,B7-H4-Fc protein group,Ig G2a-Fc group,Anti-B7-H4 m Ab group and Ig G isotype control group.After 0 days,15 days and 30 days,blood was taken from the canthus of the mice after anesthesia,and the spleen and submandibular glands were taken out.The changes of lymphocyte subsets in spleen single cell suspension were detected by flow cytometry,and the submandibular gland tissue was stained with HE and immunohistochemistry.Statistical analysis was carried out by single factor analysis of variance or two independent sample t test.Results(1)Costimulatory molecule B7-H4 protein was mainly expressed in cytoplasm of submandibular gland ductal endothelial cells in NOD mice.A low expression of B7-H4 protein was found in a large number of lymphocytes infiltrated in the submandibular gland.(2)The degree of inflammatory infiltration of submandibular gland in NOD mice was significantly reduced after intraperitoneal injection of B7-H4-Fc fusion protein at day 30.The percentages of CD4+ Foxp3+ T cells in spleen were significantly increased in B7-H4-Fc group compared with Ig G2a-Fc group,NSgroup and baseline group respectively(P = 0.005,P = 0.020,P = 0.012).The percentage of CD4+ IFN-γ + T cells in B7-H4-Fc group was significantly lower than that in Ig G2a-Fc group,NS group and baseline group(P <0.001,P <0.001,P = 0.013).There was no significant difference in the proportion of CD4+IL-17+T cells in the spleen between the three groups in the proportion of CD4+T cells.(3)The percentage of CD4+Foxp3+T cells in CD4+T cells was significantly lower(P=0.012)and CD4+IFN-γ +T cells in CD4+T cells was higher(P=0.007)in Anti-B7-H4 m Ab group compared to Ig G control group at day 15.There was no statistical difference in the proportion of CD4+IL-17+T cells in CD4+T cells.Conclusion B7-H4 protein can delay the infiltration of lymphocyte in the submandibular gland of NOD mice,reduce the level of inflammatory cytokines and inhibit the progress of autoimmune inflammation.