The mystery of tuberculosis pathogenesis from the perspective of T regulatory cells

It must be admitted that Mycobacterium tuberculosis (Mtb) is one of the worst microorganisms in nature. This bacterium causes tuberculosis (TB) disease, as a terrible infectious disease with a high rate of mortality and morbidity. However, most cases are afflicted to the non-active (latent) form of diseases. It bases the main arm of the immune response against TB is based on cellular immunity response. As a rule of thumb, contribution between macrophages and dendritic cells as processing cells on one hand, and T lymphocyte cells as fateful cells, have a pivotal role in the eradication of TB infection. But, the excessive presence of immune cells in the infection area leads to tissue damage. Recruitment of T regulatory (T reg) cells can be essential to prevention damage and subsequently creates a state of balance in the site of infection. Some expressed immune protein and cytokines from these cells such as FOXP3 (scurfin) and IL-10 have key importance in quenching of tissue lesions. In the present study, we have discussed the perspective of T reg cells in the TB infection. Based on the information in this study, it is concluded that the excessive presence of cytokines such as IFN-gamma has a damaging effect on infected tissues. T reg cells as the main suppression cell group have a substantial role in the balance of the immune system. The T reg cells possess a broad range of cytokines such as IL-10, IL-35, TGF-beta, granzymes, Galectin-1, CD39, CD73, CTLA4, and also other unknown mechanisms which contribute in their suppressive and balancing effects. In this review we discussed the key roles of T regulatory cells in immune-pathogenesis state of tuberculosis. The findings of this review will have implications for determining role of T reg cells in different forms of tuberculosis and also can open a new avenue for planning novel therapeutic agents against TB.