Human Alveolar and Splenic Macrophage Populations Display a Distinct Transcriptomic Response to Infection With Mycobacterium tuberculosis

ABSTRACT Mycobacterium bovis bacillus Calmette-Guérin (BCG) currently remains the only licensed vaccine for the prevention of tuberculosis. In this study, we used a newly described flow cytometric technique to monitor changes in cell populations accumulating in the lungs and lymph nodes of naïve and vaccinated guinea pigs challenged by low-dose aerosol infection with virulent Mycobacterium tuberculosis. As anticipated, vaccinated guinea pigs controlled the growth of the challenge infection more efficiently than controls did. This early phase of bacterial control in immune animals was associated with increased accumulation of CD4 and CD8 T cells, including cells expressing the activation marker CD45, as well as macrophages expressing class II major histocompatibility complex molecules. As the infection continued, the numbers of T cells in the lungs of vaccinated animals waned, whereas the numbers of these cells expressing CD45 increased. Whereas BCG vaccination reduced the influx of heterophils (neutrophils) into the lungs, an early B-cell influx was observed in these vaccinated animals. Overall, vaccine protection was associated with reduced pathology and lung damage in the vaccinated animals. These data provide the first direct evidence that BCG vaccination accelerates the influx of protective T-cell and macrophage populations into the infected lungs, diminishes the accumulation of nonprotective cell populations, and reduces the severity of lung pathology.

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Transcriptomic Profile of Mycobacterium smegmatis in Response to an Imidazo[1,2-b][1,2,4,5]tetrazine Reveals Its Possible Impact on Iron Metabolism

Frontiers in Microbiology ◽

10.3389/fmicb.2021.724042 ◽

2021 ◽

Vol 12 ◽

Author(s):

Aleksey A. Vatlin ◽

Egor A. Shitikov ◽

Mohd Shahbaaz ◽

Dmitry A. Bespiatykh ◽

Ksenia M. Klimina ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Mechanism Of Action ◽

Iron Metabolism ◽

Mycobacterium Smegmatis ◽

New Drugs ◽

Dependent Manner ◽

Tuberculosis Control ◽

Transcriptomic Response ◽

Dose Dependent ◽

Siderophore Synthesis

Tuberculosis (TB), caused by the Mycobacterium tuberculosis complex bacteria, is one of the most pressing health problems. The development of new drugs and new therapeutic regimens effective against the pathogen is one of the greatest challenges in the way of tuberculosis control. Imidazo[1,2-b][1,2,4,5]tetrazines have shown promising activity against M. tuberculosis and M. smegmatis strains. Mutations in MSMEG_1380 lead to mmpS5–mmpL5 operon overexpression, which provides M. smegmatis with efflux-mediated resistance to imidazo[1,2-b][1,2,4,5]tetrazines, but the exact mechanism of action of these compounds remains unknown. To assess the mode of action of imidazo[1,2-b][1,2,4,5]tetrazines, we analyzed the transcriptomic response of M. smegmatis to three different concentrations of 3a compound: 1/8×, 1/4×, and 1/2× MIC. Six groups of genes responsible for siderophore synthesis and transport were upregulated in a dose-dependent manner, while virtual docking revealed proteins involved in siderophore synthesis as possible targets for 3a. Thus, we suggest that imidazo[1,2-b][1,2,4,5]tetrazines may affect mycobacterial iron metabolism.

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The Glycan-Rich Outer Layer of the Cell Wall of Mycobacterium tuberculosis Acts as an Antiphagocytic Capsule Limiting the Association of the Bacterium with Macrophages

Infection and Immunity ◽

10.1128/iai.72.10.5676-5686.2004 ◽

2004 ◽

Vol 72 (10) ◽

pp. 5676-5686 ◽

Cited By ~ 86

Author(s):

Richard W. Stokes ◽

Raymond Norris-Jones ◽

Donald E. Brooks ◽

Terry J. Beveridge ◽

Dan Doxsee ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Surface Hydrophobicity ◽

Host Cells ◽

Microbial Pathogens ◽

Mammalian Host ◽

Human Macrophage ◽

Bacterial Surface ◽

Important Virulence Factor ◽

Complement Receptor 3 ◽

Macrophage Populations

ABSTRACT Mycobacterium tuberculosis, the causative agent of tuberculosis, is a facultative intracellular pathogen that infects macrophages and other host cells. We show that sonication of M. tuberculosis results in the removal of material from the surface capsule-like layer of the bacteria, resulting in an enhanced propensity of the bacteria to bind to macrophages. This effect is observed with disparate murine and human macrophage populations though, interestingly, not with freshly explanted alveolar macrophages. Enhanced binding to macrophages following sonication is significantly greater within members of the M. tuberculosis family (pathogens) than within the Mycobacterium avium complex (opportunistic pathogens) or for Mycobacterium smegmatis (saprophyte). Sonication does not affect the viability or the surface hydrophobicity of M. tuberculosis but does result in changes in surface charge and in the binding of mannose-specific lectins to the bacterial surface. The increased binding of sonicated M. tuberculosis was not mediated through complement receptor 3. These results provide evidence that the surface capsule on members of the M. tuberculosis family may be an important virulence factor involved in the survival of M. tuberculosis in the mammalian host. They also question the view that M. tuberculosis is readily ingested by any macrophage it encounters and support the contention that M. tuberculosis, like many other microbial pathogens, has an antiphagocytic capsule that limits and controls the interaction of the bacterium with macrophages.

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Comparative ‘omics analyses differentiate Mycobacterium tuberculosis and Mycobacterium bovis and reveal distinct macrophage responses to infection with the human and bovine tubercle bacilli

10.1101/220624 ◽

2017 ◽

Cited By ~ 1

Author(s):

Kerri M. Malone ◽

Kévin Rue-Albrecht ◽

David A. Magee ◽

Kevin Conlon ◽

Olga T. Schubert ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Mycobacterium Bovis ◽

Host Preference ◽

Innate Immune ◽

Genetic Identity ◽

Macrophage Infection ◽

Transcriptomic Response ◽

Significant Differential Expression ◽

Host Tropism ◽

High Degree

AbstractMembers of the Mycobacterium tuberculosis complex (MTBC) are the causative agents of tuberculosis in a range of mammals, including humans. A key feature of MTBC pathogens is their high degree of genetic identity, yet distinct host tropism. Notably, while Mycobacterium bovis is highly virulent and pathogenic for cattle, the human pathogen M. tuberculosis is attenuated in cattle. Previous research also suggests that host preference amongst MTBC members has a basis in host innate immune responses. To explore MTBC host tropism, we present in-depth profiling of the MTBC reference strains M. bovis AF2122/97 and M. tuberculosis H37Rv at both the global transcriptional and translational level via RNA-sequencing and SWATH mass spectrometry. Furthermore, a bovine alveolar macrophage infection time course model was employed to investigate the shared and divergent host transcriptomic response to infection with M. tuberculosis or M. bovis. Significant differential expression of virulence-associated pathways between the two bacilli was revealed, including the ESX-1 secretion system. A divergent transcriptional response was observed between M. tuberculosis and M. bovis infection of bovine alveolar macrophages, in particular cytosolic DNA-sensing pathways at 48 hours post-infection, and highlights a distinct engagement of M. bovis with the bovine innate immune system. The work presented here therefore provides a basis for the identification of host innate immune mechanisms subverted by virulent host-adapted mycobacteria to promote their survival during the early stages of infection.ImportanceThe Mycobacterium tuberculosis complex (MTBC) includes the most important global pathogens for humans and animals, namely Mycobacterium tuberculosis and Mycobacterium bovis, respectively. These two exemplar mycobacterial pathogens share a high degree of genetic identity, but the molecular basis for their distinct host preference is unknown. In this work we integrated transcriptomic and proteomic analyses of the pathogens to elucidate global quantitative differences between them at the mRNA and protein level. We then integrated this data with transcriptome analysis of the bovine macrophage response to infection with either pathogen. Increased expression of the ESX-1 virulence system in M. bovis appeared a key driver of an increased cytosolic nucleic acid sensing and interferon response in bovine macrophages infected with M. bovis compared to M. tuberculosis. Our work demonstrates the specificity of host-pathogen interaction and how the subtle interplay between mycobacterial phenotype and host response may underpin host specificity amongst MTBC members.

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