Effects Of Mycobacterium Neoaurum On Spleen Tregs Phenotype And Function Of Mice

In recent years,clinical cases of nontuberculous mycobacteria disease continue to increase,and nontuberculous mycobacteria disease has become a serious problem that endangers human life and health.There is no cure for nontuberculous mycobacteria disease currently.Regulatory T cells are a class of T cell subsets that negatively regulate the body's immune response,which can not only inhibit the body's immune response,but also limit the scope and extent of immune response.Therefore,this study was conducted to investigate C57 BL / 6 mice infected with Mycobacterium neoaurum,and analyze the phenotype and function of Tregs subgroup during infection.Therefore we will understand the immune mechanism of Tregs during nontuberculous mycobacteria infection further.Female C57BL/6 mice were infected intraperitoneally with Mycobacterium neoaurum.Dynamic change of the percentage of CD₄⁺CD₂₅⁺Fox P3⁺and CD8⁺CD₂₅⁺Fox P3⁺ Treg cell in spleen were detected by flow cytometry at 1,2,3,4,5,6,7,9,11,13,16,18 and 23 weeks after infection.Inhibitory function was detected by using CD152 at the time that phenotype changed significantly.CD₄⁺CD₂₅⁺Treg and CD₄⁺CD₂₅-T cells were isolated from the splenic tissue by magnetic cell sorting?MACS?system and tested for MTT proliferation suppression assay.Through quantitative real PCR,Foxp3,IFN-?,TGF-? and IL-10 m RNA were detected in CD₄⁺CD₂₅⁺Treg cells.The results showed that :1.In the spleen of mice infected with M.neoaurum,the Tregs subgroup mainly existed as CD₄⁺CD₂₅⁺Fox P3⁺Treg phenotype and had the highest proportion of cells at 6th week.The percentage of CD₄⁺CD₂₅⁺Fox P3⁺Treg reached about 2%.CD₄⁺CD₂₅⁺CD152⁺ Treg and CD₄⁺CD₂₅⁺Fox P3⁺ Treg cells were positively correlated.2.The purity of CD₄⁺CD₂₅⁺Treg and CD₄⁺CD₂₅-T cells isolated by MACS was high.The percentage of CD₄⁺CD₂₅-T cells could reach 82.5%.CD₄⁺CD₂₅⁺ Treg could reach 79.15%.CD₄⁺CD₂₅⁺Treg can inhibit CD₄⁺CD₂₅-T cells by direct contact.3.The expression of FoxP3,IL-10 and TGF-? mRNA in CD₄⁺CD₂₅⁺Treg in M.neoaurum infected mice was significantly different from that in control group,and the expression of IFN-? had no significant difference between infected mice and control group.In conclusion,the Tregs subgroup mainly existed as CD₄⁺CD₂₅⁺Fox P3⁺Treg phenotype in the spleen of mice infected with M.neoaurum and played an important role in immunosuppressive effects.CD₄⁺CD₂₅⁺Treg could inhibit the proliferation of CD₄⁺CD₂₅-T cells in vitro.It was confirmed that CD₄⁺CD₂₅⁺Treg could exert inhibitory function by direct contact.CD₄⁺CD₂₅⁺Treg cells played an immunosuppressive role mainly by secreting cytokines TGF-? and IL-10.