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1.
BMC Immunol ; 21(1): 34, 2020 06 09.
Article in English | MEDLINE | ID: mdl-32517651

ABSTRACT

BACKGROUND: Tuberculosis is an important health problem worldwide. The only available vaccine is M. bovis/BCG, an attenuated mycobacterium that activates the innate and the acquired immune system after being phagocytosed by macrophages and dendritic cells. Vaccination fails to prevent adult pulmonary tuberculosis although it may have a protective effect in childhood infection. Understanding how BCG interacts with macrophages and other immunocompetent cells is crucial to develop new vaccines. RESULTS: In this study we showed that macrophages phagocytose M. bovis/BCG bacilli with higher efficiency when they are cultured without phosphate. We isolated mycobacterial membranes to search for mycobacterial molecules that could be involved in these processes; by immunoblot, it was found that the plasma membranes of phosphate-deprived bacilli express the adhesins PstS-1, LpqH, LprG, and the APA antigen. These proteins are not detected in membranes of bacilli grown with usual amounts of phosphate. CONCLUSIONS: The interest of our observations is to show that under the metabolic stress implied in phosphate deprivation, mycobacteria respond upregulating adhesins that could improve their capacity to infect macrophages. These observations are relevant to understand how M. bovis/BCG induces protective immunity.


Subject(s)
BCG Vaccine/immunology , Macrophages/immunology , Mycobacterium bovis/immunology , Phagocytosis/immunology , Phosphates/immunology , Tuberculosis, Pulmonary/immunology , Adaptive Immunity/immunology , Animals , Antigens/immunology , Cell Line, Tumor , Cell Membrane/immunology , Immunity, Innate/immunology , Mice , Mice, Inbred BALB C , Vaccination/methods
2.
PLoS One ; 13(12): e0207202, 2018.
Article in English | MEDLINE | ID: mdl-30532264

ABSTRACT

Due to prolonged coevolution with the human being, Mycobacterium tuberculosis has acquired a sophisticated capacity to evade host immunity and persist in a latent state in the infected individual. As part of this evolutive process, mycobacteria have developed a highly complex cell wall that acts as a protective barrier. Herein we studied the effects of Di-O-acyl trehalose, a cell-wall glycolipid of virulent mycobacteria on murine bone marrow-derived dendritic cells. We have demonstrated that Di-O-Acyl-trehalose promotes a tolerogenic phenotype in bone marrow-derived murine DCs activated with mycobacterial antigens and Toll-like receptor agonists. This phenotype included low expression of antigen presentation and costimulatory molecules and altered cytokine production with downregulation of IL-12 and upregulation of IL-10, an anti-inflammatory cytokine. Additional markers of tolerogenicity were the expression of Indoleamine 2,3-dioxygenase and CD25. Furthermore, Di-O-Acyl-Trehalose promoted the expansion of FoxP3+ regulatory T lymphocytes. A better understanding of mycobacterial cell-wall components involved in the evasion of immunity is a prerequisite to designing better strategies to fight tuberculosis.


Subject(s)
Dendritic Cells/drug effects , Dendritic Cells/immunology , Immune Tolerance/drug effects , Mycobacterium tuberculosis/chemistry , Trehalose/analogs & derivatives , Trehalose/pharmacology , Animals , Antigens, Bacterial/immunology , Dendritic Cells/cytology , Dendritic Cells/metabolism , Female , Indoleamine-Pyrrole 2,3,-Dioxygenase/metabolism , Interleukin-10/metabolism , Interleukin-12/biosynthesis , Mice , Mice, Inbred C57BL , T-Lymphocytes, Regulatory/cytology , T-Lymphocytes, Regulatory/drug effects , Up-Regulation/drug effects
3.
PLoS One ; 12(8): e0182126, 2017.
Article in English | MEDLINE | ID: mdl-28767693

ABSTRACT

While homeostatic apoptosis is immunologically silent, macrophage apoptosis during Mycobacterium tuberculosis infection can potentially induce an immune response against the mycobacteria. To examine the role of dendritic cells in this response, macrophage apoptosis was induced by incubating the macrophage with cell wall extracts of mycobacteria expressing LpqH. The apoptogenic proteins of the cell wall extracts were engulfed by the macrophage and then were translocated from the cytosol to the nuclei of the dying cells. Dendritic cells that engulfed the apoptotic macrophages acquired an immunogenic phenotype that included upregulation of MHC-I, increased expression of the costimulatory molecules, CD40, CD80, and CD86, and increased production of IL-12, IL-10, TNF-α, and TGF-ß. In addition, the dendritic cells triggered a proliferative response of CD8+ T cells with IFN-γ production via cross-presentation. Taken together, these findings support a model in which phagocytosis of whole apoptotic cells carrying mycobacterial antigens promotes a potentially protective immune response.


Subject(s)
Bacterial Proteins/metabolism , CD8-Positive T-Lymphocytes/immunology , Dendritic Cells/cytology , Macrophages/cytology , Mycobacterium tuberculosis/metabolism , Tuberculosis/immunology , Animals , Antigen Presentation , Apoptosis , Apoptosis Regulatory Proteins/metabolism , Cell Proliferation , Cells, Cultured , Dendritic Cells/immunology , Lymphocyte Activation , Mice , Phagocytosis
4.
J Immunol Res ; 2016: 3845247, 2016.
Article in English | MEDLINE | ID: mdl-27413759

ABSTRACT

Upon Mycobacterium tuberculosis infection, macrophages may undergo apoptosis, which has been considered an innate immune response. The pathways underlying the removal of dead cells in homeostatic apoptosis have been extensively studied, but little is known regarding how cells that undergo apoptotic death during mycobacterial infection are removed. This study shows that macrophages induced to undergo apoptosis with mycobacteria cell wall proteins are engulfed by J-774A.1 monocytic cells through the mannose receptor. This demonstration was achieved through assays in which phagocytosis was inhibited with a blocking anti-mannose receptor antibody and with mannose receptor competitor sugars. Moreover, elimination of the mannose receptor by a specific siRNA significantly diminished the expression of the mannose receptor and the phagocytosis of apoptotic cells. As shown by immunofluorescence, engulfed apoptotic bodies are initially located in Rab5-positive phagosomes, which mature to express the phagolysosome marker LAMP1. The phagocytosis of dead cells triggered an anti-inflammatory response with the production of TGF-ß and IL-10 but not of the proinflammatory cytokines IL-12 and TNF-α. This study documents the previously unreported participation of the mannose receptor in the removal of apoptotic cells in the setting of tuberculosis (TB) infection. The results challenge the idea that apoptotic cell phagocytosis in TB has an immunogenic effect.


Subject(s)
Apoptosis , Cell Wall/immunology , Lectins, C-Type/physiology , Macrophages/immunology , Mannose-Binding Lectins/physiology , Monocytes/immunology , Mycobacterium smegmatis/immunology , Phagocytosis , Receptors, Cell Surface/physiology , Animals , Cell Line, Tumor , Extracellular Vesicles/ultrastructure , Fluorescent Antibody Technique , Interleukin-10/metabolism , Interleukin-12/metabolism , Lectins, C-Type/genetics , Lysosomal Membrane Proteins/genetics , Lysosomal Membrane Proteins/metabolism , Macrophages/cytology , Macrophages/microbiology , Mannose Receptor , Mannose-Binding Lectins/genetics , Mice , Mycobacterium smegmatis/growth & development , Phagosomes/immunology , Phagosomes/ultrastructure , RNA, Small Interfering , Receptors, Cell Surface/genetics , Transforming Growth Factor beta/metabolism , Tumor Necrosis Factor-alpha/metabolism , rab5 GTP-Binding Proteins/analysis
5.
BMC Immunol ; 16: 38, 2015 Jun 23.
Article in English | MEDLINE | ID: mdl-26100760

ABSTRACT

BACKGROUND: Tuberculosis (TB) remains a serious human health problem that affects millions of people in the world. Understanding the biology of Mycobacterium tuberculosis (Mtb) is essential for tackling this devastating disease. Mtb possesses a very complex cell envelope containing a variety of lipid components that participate in the establishment of the infection. We have previously demonstrated that di-O-acylated trehalose (DAT), a non-covalently linked cell wall glycolipid, inhibits the proliferation of T lymphocytes and the production of cytokines. RESULTS: In this work we show that DAT and the closely related tri-O-acylated trehalose (TAT) inhibits nitric oxide (NO) production and the inducible nitric oxide synthase (iNOS) expression in macrophages (MØ). CONCLUSIONS: These findings show that DAT and TAT are cell-wall located virulence factors that downregulate an important effector of the immune response against mycobacteria.


Subject(s)
Glycolipids/pharmacology , Macrophages/enzymology , Mycobacterium/chemistry , Nitric Oxide Synthase Type II/metabolism , Nitric Oxide/biosynthesis , Trehalose/pharmacology , Acylation/drug effects , Animals , Bone Marrow Cells/cytology , Bone Marrow Cells/drug effects , Bone Marrow Cells/metabolism , Down-Regulation/drug effects , Glycolipids/isolation & purification , Interferon-gamma/pharmacology , Lipopolysaccharides/pharmacology , Macrophages/drug effects , Mice, Inbred BALB C , Trehalose/isolation & purification
6.
Tuberc Res Treat ; 2010: 517547, 2010.
Article in English | MEDLINE | ID: mdl-22567259

ABSTRACT

Patients with tuberculosis frequently develop anergy, a state of T-cell hyporesponsiveness in which defective T-cell costimulation could be a factor. To know if the expression of T-cell costimulatory molecules was altered in tuberculosis, we analyzed the peripheral blood T-cell phenotype of 23 Mexican patients with pulmonary tuberculosis. There was severe CD4 (P < .001) and CD8 (P < .01) lymphopenia and upregulation of costimulatory molecule CD30 on CD4 and CD8 T cells (P < .05); this increase was higher in relapsing tuberculosis. The main finding was severe downregulation of the major costimulatory molecule CD28 on both CD8 and CD4 T cells (P < .001). Depletion of the CD4/CD28 subset, a hitherto undescribed finding, is relevant because CD4 T cells constitute the main arm of the cell-mediated antimycobacterial immune response.

7.
J Clin Lab Anal ; 20(3): 80-6, 2006.
Article in English | MEDLINE | ID: mdl-16721821

ABSTRACT

While the detrimental consequences of opportunistic tuberculosis (TB) in the course and outcome of HIV-1 infection are well studied, little information about the impact of the mycobacterial infection on the phenotype of T lymphocytes is available. In this study we analyzed by cytofluorimetry the peripheral blood T cell phenotype of 13 patients with AIDS, 23 HIV-1 negative patients with active pulmonary TB, nine HIV-1/Mycobacterium tuberculosis coinfected individuals, and 21 age- and sex-matched healthy controls. CD4+ T cells were equally depleted in AIDS and coinfection (P<0.001). The findings suggest a rescuing effect of the added mycobacterial infection. CD3 T cell loss was not observed in coinfection, whereas it was severe in AIDS (P<0.001). Similar (albeit less striking) effects were observed with other markers (CD45RA, CD45RO, and CD27) that were diminished in CD4+ T cells of AIDS patients. Apparent detrimental effects of the added mycobacterial infection were the increased expression of the proapoptotic molecule CD95 on CD4+ T cells, and decreased expression of the major costimulatory molecule CD28 on CD8+ T cells. In this work we show that M. tuberculosis infection modifies the T cell phenotype of the HIV-1 infected individual.


Subject(s)
AIDS-Related Opportunistic Infections/immunology , CD4-Positive T-Lymphocytes/immunology , HIV-1/immunology , Immunocompromised Host , Tuberculosis, Pulmonary/immunology , AIDS-Related Opportunistic Infections/blood , AIDS-Related Opportunistic Infections/pathology , Adult , Aged , Female , Flow Cytometry , HIV-1/isolation & purification , Humans , Immunophenotyping , Male , Middle Aged , Tuberculosis, Pulmonary/blood , Tuberculosis, Pulmonary/pathology
8.
Microb Pathog ; 39(3): 97-107, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16098710

ABSTRACT

Identification of mycobacterial adhesins is needed to understand better the pathogenesis of tuberculosis and to develop new strategies to fight this infection. In this work, THP-1 monocytic cells were incubated with Mycobacterium tuberculosis culture filtrate proteins labelled with biotin and a dominant 19-kDa adhesin was found. This adhesin was characterized as the glycosylated and acylated 19-kDa antigen (Rv 3763). These findings were confirmed in assays with culture filtrate proteins and cell-wall fractions from a recombinant Mycobacterium smegmatis strain that overexpresses the 19-kDa antigen. Further, fluorescent microspheres coated with recombinant culture filtrate proteins adhere to cells in higher numbers than microspheres coated with native M. smegmatis proteins. The binding of the 19-kDa antigen to cells was inhibited with mannose receptor competitor sugars, Ca(2+) chelators and with a monoclonal antibody to the human mannose receptor. Phagocytosis assays showed high-level binding of bacilli to THP-1 cells that was inhibited with alpha-methyl-mannoside, mannan, EDTA and mAbs to the mannose receptor and to the 19-kDa M. tuberculosis antigen. Immunoprecipitation, cell-surface ELISA and immunostaining confirmed the expression of the mannose receptor by THP-1 cells. In conclusion, here we show that the macrophage mannose receptor, considered a pathogen pattern recognition receptor, may interact with mannose residues of mycobacterial glycoproteins that could promote the phagocytosis of mycobacteria.


Subject(s)
Adhesins, Bacterial/immunology , Lectins, C-Type/immunology , Mannose-Binding Lectins/immunology , Monocytes/immunology , Mycobacterium tuberculosis/immunology , Phagocytosis/immunology , Receptors, Cell Surface/immunology , Tuberculosis/microbiology , Acetylglucosamine/pharmacology , Adhesins, Bacterial/metabolism , Antigens, Bacterial/immunology , Bacterial Adhesion , Enzyme-Linked Immunosorbent Assay , Humans , Immunoblotting , Immunoprecipitation , Lectins, C-Type/metabolism , Mannans/pharmacology , Mannose Receptor , Mannose-Binding Lectins/metabolism , Methylmannosides/pharmacology , Monocytes/metabolism , Monocytes/microbiology , Mycobacterium tuberculosis/metabolism , Protein Binding/immunology , Receptors, Cell Surface/metabolism
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