Study On The Effects Of Ntm On The Differentiation Of CD~4+T Cells In Mice

Nontuberculous mycobacterium(NTM) belong to the Mycobacterium except the MTC and M. leprae, which are a kind of environmental pathogens. It widely exists in the natural environment. At present, the cases of NTM infection had been reported. In addition, a lot of NTM had been isolated from animals. Thus it can be seen that non-tuberculosis mycobacteria have posed a threat to human health. But most studies about NTM are mainly concentrated on the epidemiological investigation, laboratory diagnosis and drug sensitive experiment research, the research of NTM pathogenic mechanism is less. CD4+T cells are the core of immune cells in anti mycobacterium immune, CD4+T cells can divide into Th1, Th2, of Th17 and Treg cells, and the four cell function are different. To a certain extent, the differentiation of CD4+T cell reflects the body’s immune condition and also help to study of pathogenic mechanism in anti mycobacterium infection.In order to explore the differentiation of CD4+T cell after infection with the mycobacterium tuberculosis bacteria, the C57BL/6 mice are attacked by 3 log10 CFU of M.gilvum or M.neoaurum through abdominal cavity, we also set up the normal saline control group, made the pathological slices of lung tissue and acid-fast staining for detecting the NTM in lung on 20 th, 32 th, 44 th and 56 th day after infection; we alse observed the dynamic of the transcription of T-bet, GATA-3, RORγt and Foxp3 mRNA by qRT-PCR, and the dynamic of the percentage of Th1, Th2, Th17 and Treg cell by using flow cytometry on 20 th, 32 th, 44 th and 56 th day.The result shows that: We observed the infiltration of inflammatory cells in lung tissue pathological slices on 20 th, 32 th, 44 th and 56 th. after infection, but the pathological slices were a slight of difference in mice. on the 20 th day, the alveolar walls of M.gilvum group were thicker than the M.neoaurum’s, on the 44 th day, there were inflammatory cells and exudate in alveolar space after infecting M.gilvum, howerer, there were inflammatory cells infiltration and the necrosis of epithelial cell alveolar in lung tissue after infecting M.neoaurum.There were not typical pathological changes of tuberculosis in two groups. We detected NTM in lung on 20 th, 32 th, 44 th and 56 th day after infecting M.gilvum or M.neoaurum by acid fast stain. when we studied the differentiation of CD4+T cell in mice’s lung after infecting with NTM, we found that the relative levels of GATA-3 mRNA、the percentage of Th2 cells、the relative levels of RORγt mRNA and the percentage of Th17 cells were significantly higher than the control group(P<0.05), but the relative levels of T-bet mRNA、the percentage of Th1 cells、the relative levels of Foxp3 mRNA and the percentage of Treg cells significantly lower than the control group(P<0.05)on the 20 th day after infecting with M.gilvum; on the 44 th and 56 th after infecting with M.gilvum, the relative levels of RORγt mRNA and the percentage of Th17 cells are lower than the control group,the relative levels of Foxp3 mRNA and the percentage of Treg cells are higher than the control group, the results all had the biological statistic significance(P<0.05). nevertheless, on the 20 th day, the relative levels of T-bet mRNA and the percentage of Th1 cells were significantly higher than the control group(P<0.05) after infecting with M.neoaurum; the relative levels of GATA-3 mRNA on the 32 th and 44 th day,and the percentage of Th2 cells on the 44 th and 56 th day after infection were significantly higher than the control group(P<0.05); the relative levels of Foxp3 mRNA and percentage of Treg cells were significantly higher than the control group on the 56 th day after infection(P<0.05), however, the relative levels of RORγt mRNA and the percentage of Th17 cells were lower at this time(P<0.05). The results above suggest: CD4+T cell can differentiate into the different cell subgroups at different time after infecting with these two kinds of NTM. On the 20 th day, CD4+T cells differentiate into the Th2 and Th17 cell, and inhibit the Th1 and Treg cells after infecting with M.gilvum, on the 44 th and 56 th day CD4+T cells differentiate into Treg cells, and inhibit the the differentiation of Th17 cell after infection. At the same time, on the 20 th day, CD4+T cells differentiate into the Th1 cell after infecting with M.neoaurum, on the 56 th day, CD4+T cells differentiate into Th2 and Treg cells, and inhibited the Th17 cell differentiation after infection.This experiment first studied the influence of M.gilvum and M.neoaurum on the differentiation of CD4+T cell in mice. It help us to understand the body’s immunity after infecting with NTM, and also provide the reference and new ways to the pathogenesis of NTM、 diagnosis and NTM prevention.