krn-7000 and Tuberculosis

The critical role of peptide antigen-specific T cells in controlling mycobacterial infections is well documented in natural resistance and vaccine-induced immunity against Mycobacterium tuberculosis. However, many other populations of leukocytes contribute to innate and adaptive immunity against mycobacteria. Among these, non-conventional T cells recognizing lipid antigens presented by the CD1 antigen presentation system have attracted particular interest. In this chapter, we review the basic immunobiology and potential antimycobacterial properties of a subset of CD1-restricted T cells that have come to be known as Natural Killer T cells. This group of lipid reactive T cells is notable for its high level of conservation between humans and mice, thus enabling a wide range of highly informative studies in mouse models. As reviewed below, NKT cells appear to have subtle but potentially significant activities in the host response to mycobacteria. Importantly, they also provide a framework for investigations into other types of lipid antigen-specific T cells that may be more abundant in larger mammals such as humans.

Topics: Animals; Antigen Presentation; Antigens, Bacterial; Antigens, CD1d; Cell Membrane; Clonal Selection, Antigen-Mediated; Disease Models, Animal; Endosomes; Galactosylceramides; Glycolipids; Humans; Immunity, Innate; Lymphocyte Activation; Mammals; Mice; Mice, Knockout; Mycobacterium bovis; Mycobacterium tuberculosis; Natural Killer T-Cells; Protein Transport; T-Lymphocyte Subsets; Tuberculosis

Immune-modulating drugs that target myeloid-derived suppressor cells or stimulate natural killer T cells have been shown to reduce mycobacterial loads in tuberculosis (TB). We aimed to determine if a combination of these drugs as adjunct immunotherapy to conventional antibiotic treatment could also increase therapeutic efficacy against TB. In our model of pulmonary TB in mice, we applied treatment with isoniazid, rifampicin, and pyrazinamide for 13 weeks alone or combined with immunotherapy consisting of all-trans retinoic acid, 1,25(OH)

Topics: Animals; Anti-Bacterial Agents; Antitubercular Agents; Cholecalciferol; Combined Modality Therapy; Disease Models, Animal; Female; Galactosylceramides; Immunity, Cellular; Immunotherapy; Lung; Mice, Inbred BALB C; Recurrence; Tretinoin; Tuberculosis; Tumor Necrosis Factor-alpha

Natural killer T (NKT) cells are known to play a protective role in the immune responses of mice against a variety of infectious pathogens. However, little is known about the detailed information of NKT cells in patients with Mycobacterium tuberculosis infection. The aims of this study were to examine NKT cell levels and functions in patients with active M. tuberculosis infection, to investigate relationships between NKT cell levels and clinical parameters, and to determine the mechanism responsible for the poor response to α-galactosylceramide (α-GalCer). NKT cell levels were significantly lower in the peripheral blood of pulmonary tuberculosis and extrapulmonary tuberculosis patients, and the proliferative responses of NKT cells to α-GalCer were also lower in patients, whereas NKT cell levels and responses were comparable in latent tuberculosis infection subjects and healthy controls. Furthermore, this NKT cell deficiency was found to be correlated with serum C-reactive protein levels. In addition, the poor response to α-GalCer in M. tuberculosis-infected patients was found to be due to increased NKT cell apoptosis, reduced CD1d expression, and a defect in NKT cells. Notably, M. tuberculosis infection was associated with an elevated expression of the inhibitory programmed death-1 (PD-1) receptor on NKT cells, and blockade of PD-1 signaling enhanced the response to α-GalCer. This study shows that NKT cell levels and functions are reduced in M. tuberculosis-infected patients and these deficiencies were found to reflect the presence of active tuberculosis.

Topics: Adult; Aged; Animals; Case-Control Studies; Cell Death; Cell Proliferation; Cohort Studies; Female; Galactosylceramides; Gene Expression Regulation; Humans; Male; Mice; Middle Aged; Natural Killer T-Cells; Programmed Cell Death 1 Receptor; Tuberculosis