The role of γδT cells in the pathogenesis of Tuberculosis

Author: Tekle Kalichava
Keywords: Tuberculosis, γδT cell, immune response
Annotation:

Infectious disease Tuberculosis (TB) is a global health problem of the world in our days. Georgia belongs to the high TB incidence countries. In Georgia, 3611 tuberculosis cases were notified in 2015, out of these 73% were new cases. Despite the fact, that some progress has been made over the last decade to reduce TB incidents and mortality, according to the classification of World Health Organization, TB remains a leading cause of morbidity and mortality in developing countries. Due to the alarming incidence of TB in Georgia with a high proportion of MDR, studying immune responses to Mycobacterium tuberculosis with the aim of possible immunomodulation treatment is of paramount importance. Of the immune components involved in the recognition and responses to Mycobacterium tuberculosis infection, γδ T cells have recently became the focus of attention. With increasing appreciation of their importance in the surveillance and/or resistance to this microorganism. Some studies have indicated that γδ T cells are a source of IL17 in response to Mycobacterium tuberculosis and are likely to be involved in protective innate immunity. There is no information of which γδ T cell subset is responsible for producing the IL17. The major aim of our research represented to investigate the effect of TB infection on the γδ T cell subset. The research objects were the first time diagnosed(utreated) patients with active pulmonary tuberculosis. The role of δ T cell subsets in TB is a relatively new research topic, and no such studies have been carried out in the Georgian population. Particularly important was a comparison of the characteristics of δ T cells and their subsets in patients with active TB. The parameters, which we have chosen for studying this research, gave the opportunity to characterize the influence of TB infection`s effect on γδ T cell. The role of γδ T cell subsets in TB is a relatively new research topic. This research allowed us to discuss about the role of the γδ T cells subsets in the pathogenesis of Tuberculosis. We determined to activate subsets of γδ T cells with activation marker CD69 and formation of IL17 in subtypes of γδ T cells. As a result of our research, we received that in the peripheral blood of patients whith suffering disease, there is no significant increase or decrease in the total number of T lymphocytes, but its subpupulation, the number of γδ T cells is increased compared to the control group. Although the γδ T cells number increase is small, it is noticeable the ratio changing between the subpopulations inside it. Compared to the control group, the number of Vδ1 T cells is reduced and the number of cells Vδ2 T is increased. Vδ1 T cells activation level is reduced compared to the control group and increased Vδ2 T cells activation level. Both subgroups of γδ T cells are responsible for the production of IL 17 and the same way have been found to increase IL 17 production by Vδ2 T cells in the disease patients. Based on the results obtained, it may be concluded that the γδ T cells are involved in the pathogenesis of tuberculosis. The origination of IL17 may be responsible Vδ2 T cells subsets. since it is unknown which population is responsible for the formation of IL17. Functional study of IL17 may be the basis for the development of immunotherapy.