scholarly journals 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

2004 ◽  
Vol 72 (10) ◽  
pp. 5676-5686 ◽  
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.

scholarly journals The novel Dbl homology/BAR domain protein, MsgA, of Talaromyces marneffei regulates yeast morphogenesis during growth inside host cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Harshini Weerasinghe ◽  
Hayley E. Bugeja ◽  
Alex Andrianopoulos
Keyword(s):  
Pathogenic Fungi ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Mammalian Host ◽  
Host Immune System ◽  
Nucleotide Exchange ◽  
Phagocytic Cells ◽  
Macrophage Infection ◽  
Bar Domain ◽  
Talaromyces Marneffei

AbstractMicrobial pathogens have evolved many strategies to evade recognition by the host immune system, including the use of phagocytic cells as a niche within which to proliferate. Dimorphic pathogenic fungi employ an induced morphogenetic transition, switching from multicellular hyphae to unicellular yeast that are more compatible with intracellular growth. A switch to mammalian host body temperature (37 °C) is a key trigger for the dimorphic switch. This study describes a novel gene, msgA, from the dimorphic fungal pathogen Talaromyces marneffei that controls cell morphology in response to host cues rather than temperature. The msgA gene is upregulated during murine macrophage infection, and deletion results in aberrant yeast morphology solely during growth inside macrophages. MsgA contains a Dbl homology domain, and a Bin, Amphiphysin, Rvs (BAR) domain instead of a Plekstrin homology domain typically associated with guanine nucleotide exchange factors (GEFs). The BAR domain is crucial in maintaining yeast morphology and cellular localisation during infection. The data suggests that MsgA does not act as a canonical GEF during macrophage infection and identifies a temperature independent pathway in T. marneffei that controls intracellular yeast morphogenesis.

scholarly journals Identification of Metabolically Quiescent Leishmania mexicana Parasites in Peripheral and Cured Dermal Granulomas Using Stable Isotope Tracing Imaging Mass Spectrometry

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Joachim Kloehn ◽  
Berin A. Boughton ◽  
Eleanor C. Saunders ◽  
Sean O’Callaghan ◽  
Katrina J. Binger ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Heavy Water ◽  
Large Population ◽  
Imaging Mass Spectrometry ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Mammalian Host ◽  
Leishmania Mexicana ◽  
First Line

ABSTRACT Leishmania are sandfly-transmitted protists that induce granulomatous lesions in their mammalian host. Although infected host cells in these tissues can exist in different activation states, the extent to which intracellular parasites stages also exist in different growth or physiological states remains poorly defined. Here, we have mapped the spatial distribution of metabolically quiescent and active subpopulations of Leishmania mexicana in dermal granulomas in susceptible BALB/c mice, using in vivo heavy water labeling and ultra high-resolution imaging mass spectrometry. Quantitation of the rate of turnover of parasite and host-specific lipids at high spatial resolution, suggested that the granuloma core comprised mixed populations of metabolically active and quiescent parasites. Unexpectedly, a significant population of metabolically quiescent parasites was also identified in the surrounding collagen-rich, dermal mesothelium. Mesothelium-like tissues harboring quiescent parasites progressively replaced macrophage-rich granuloma tissues following treatment with the first-line drug, miltefosine. In contrast to the granulomatous tissue, neither the mesothelium nor newly deposited tissue sequestered miltefosine. These studies suggest that the presence of quiescent parasites in acute granulomatous tissues, together with the lack of miltefosine accumulation in cured lesion tissue, may contribute to drug failure and nonsterile cure. IMPORTANCE Many microbial pathogens switch between different growth and physiological states in vivo in order to adapt to local nutrient levels and host microbicidal responses. Heterogeneity in microbial growth and metabolism may also contribute to nongenetic mechanisms of drug resistance and drug failure. In this study, we have developed a new approach for measuring spatial heterogeneity in microbial metabolism in vivo using a combination of heavy water (2H2O) labeling and imaging mass spectrometry. Using this approach, we show that lesions contain a patchwork of metabolically distinct parasite populations, while the underlying dermal tissues contain a large population of metabolically quiescent parasites. Quiescent parasites also dominate drug-depleted tissues in healed animals, providing an explanation for failure of some first line drugs to completely eradicate parasites. This approach is broadly applicable to study the metabolic and growth dynamics in other host-pathogen interactions.

scholarly journals Integrative Analysis of Human Macrophage Inflammatory Response Related to Mycobacterium tuberculosis Virulence

2021 ◽  
Vol 12 ◽  
Author(s):  
Pauline Bade ◽  
Fabrizio Simonetti ◽  
Stephanie Sans ◽  
Patricia Laboudie ◽  
Khadija Kissane ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Inflammatory Response ◽  
Genetic Networks ◽  
Host Cells ◽  
Human Macrophage ◽  
Human Macrophages ◽  
Adaptive Immune ◽  
Adaptive Immune Cells ◽  
Main Host ◽  
Host Inflammatory Response

Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis, kills 1.5 to 1.7 million people every year. Macrophages are Mtb’s main host cells and their inflammatory response is an essential component of the host defense against Mtb. However, Mtb is able to circumvent the macrophages’ defenses by triggering an inappropriate inflammatory response. The ability of Mtb to hinder phagolysosome maturation and acidification, and to escape the phagosome into the cytosol, is closely linked to its virulence. The modulation of the host inflammatory response relies on Mtb virulence factors, but remains poorly studied. Understanding macrophage interactions with Mtb is crucial to develop strategies to control tuberculosis. The present study aims to determine the inflammatory response transcriptome and miRNome of human macrophages infected with the virulent H37Rv Mtb strain, to identify macrophage genetic networks specifically modulated by Mtb virulence. Using human macrophages infected with two different live strains of mycobacteria (live or heat-inactivated Mtb H37Rv and M. marinum), we quantified and analyzed 184 inflammatory mRNAs and 765 micro(mi)RNAs. Transcripts and miRNAs differently modulated by H37Rv in comparison with the two other conditions were analyzed using in silico approaches. We identified 30 host inflammatory response genes and 37 miRNAs specific for H37Rv virulence, and highlight evidence suggesting that Mtb intracellular-linked virulence depends on the inhibition of IL-1β-dependent pro-inflammatory response, the repression of apoptosis and the delay of the recruitment and activation of adaptive immune cells. Our findings provide new potential targets for the development of macrophage-based therapeutic strategies against TB.

scholarly journals Rv0180c contributes to Mycobacterium tuberculosis cell shape and to infectivity in mice and macrophages

2021 ◽  
Vol 17 (11) ◽  
pp. e1010020
Author(s):  
Delphine Payros ◽  
Henar Alonso ◽  
Wladimir Malaga ◽  
Arnaud Volle ◽  
Serge Mazères ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Shape ◽  
Cell Envelope ◽  
Membrane Receptors ◽  
Host Cells ◽  
Wild Type ◽  
Genes Encoding ◽  
The Difference ◽  
Complement Receptor 3 ◽  
New Perspective

Mycobacterium tuberculosis, the main causative agent of human tuberculosis, is transmitted from person to person via small droplets containing very few bacteria. Optimizing the chance to seed in the lungs is therefore a major adaptation to favor survival and dissemination in the human population. Here we used TnSeq to identify genes important for the early events leading to bacterial seeding in the lungs. Beside several genes encoding known virulence factors, we found three new candidates not previously described: rv0180c, rv1779c and rv1592c. We focused on the gene, rv0180c, of unknown function. First, we found that deletion of rv0180c in M. tuberculosis substantially reduced the initiation of infection in the lungs of mice. Next, we established that Rv0180c enhances entry into macrophages through the use of complement-receptor 3 (CR3), a major phagocytic receptor for M. tuberculosis. Silencing CR3 or blocking the CR3 lectin site abolished the difference in entry between the wild-type parental strain and the Δrv0180c::km mutant. However, we detected no difference in the production of both CR3-known carbohydrate ligands (glucan, arabinomannan, mannan), CR3-modulating lipids (phthiocerol dimycocerosate), or proteins in the capsule of the Δrv0180c::km mutant in comparison to the wild-type or complemented strains. By contrast, we established that Rv0180c contributes to the functionality of the bacterial cell envelope regarding resistance to toxic molecule attack and cell shape. This alteration of bacterial shape could impair the engagement of membrane receptors that M. tuberculosis uses to invade host cells, and open a new perspective on the modulation of bacterial infectivity.

scholarly journals Actin-Based Motility of Intracellular Microbial Pathogens

2001 ◽  
Vol 65 (4) ◽  
pp. 595-626 ◽  
Author(s):  
Marcia B. Goldberg
Keyword(s):  
Molecular Mechanisms ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Mammalian Host ◽  
Cell Periphery ◽  
Actin Assembly ◽  
Cell Cytoplasm ◽  
Shigella Spp ◽  
The Subject ◽  
Actin Rearrangement

SUMMARY A diverse group of intracellular microorganisms, including Listeria monocytogenes, Shigella spp., Rickettsia spp., and vaccinia virus, utilize actin-based motility to move within and spread between mammalian host cells. These organisms have in common a pathogenic life cycle that involves a stage within the cytoplasm of mammalian host cells. Within the cytoplasm of host cells, these organisms activate components of the cellular actin assembly machinery to induce the formation of actin tails on the microbial surface. The assembly of these actin tails provides force that propels the organisms through the cell cytoplasm to the cell periphery or into adjacent cells. Each of these organisms utilizes preexisting mammalian pathways of actin rearrangement to induce its own actin-based motility. Particularly remarkable is that while all of these microbes use the same or overlapping pathways, each intercepts the pathway at a different step. In addition, the microbial molecules involved are each distinctly different from the others. Taken together, these observations suggest that each of these microbes separately and convergently evolved a mechanism to utilize the cellular actin assembly machinery. The current understanding of the molecular mechanisms of microbial actin-based motility is the subject of this review.

scholarly journals Bordetella pertussis filamentous hemagglutinin interacts with a leukocyte signal transduction complex and stimulates bacterial adherence to monocyte CR3 (CD11b/CD18).

1994 ◽  
Vol 180 (4) ◽  
pp. 1225-1233 ◽  
Author(s):  
Y Ishibashi ◽  
S Claus ◽  
D A Relman
Keyword(s):  
Signal Transduction ◽  
Bordetella Pertussis ◽  
Whooping Cough ◽  
Bacterial Pathogen ◽  
Binding Activity ◽  
Host Cells ◽  
Bacterial Surface ◽  
Filamentous Hemagglutinin ◽  
Complement Receptor 3 ◽  
Leukocyte Response

Bordetella pertussis, the causative agent of whooping cough, adheres to human monocytes/macrophages by means of a bacterial surface-associated protein, filamentous hemagglutinin (FHA) and the leukocyte integrin, complement receptor 3 (CR3, alpha M beta 2, CD11b/CD18). We show that an FHA Arg-Gly-Asp site induces enhanced B. pertussis binding to monocytes, and that this enhancement is blocked by antibodies directed against CR3. Enhancement requires a monocyte signal transduction complex, composed of leukocyte response integrin (alpha? beta 3) and integrin-associated protein (CD47). This complex is known to upregulate CR3 binding activity. Thus, a bacterial pathogen enhances its own attachment to host cells by coopting a host cell signaling pathway.

scholarly journals Human Macrophage Gamma Interferon Decreases Gene Expression but Not Replication of Mycobacterium tuberculosis: Analysis of the Host-Pathogen Reciprocal Influence on Transcription in a Comparison of Strains H37Rv and CMT97

2001 ◽  
Vol 69 (12) ◽  
pp. 7262-7270 ◽  
Author(s):  
Giulia Cappelli ◽  
Pietro Volpe ◽  
Alessandro Sanduzzi ◽  
Alessandra Sacchi ◽  
Vittorio Colizzi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mycobacterium Tuberculosis ◽  
Transforming Growth Factor ◽  
Gamma Interferon ◽  
Host Cells ◽  
Cytokine Gene Expression ◽  
Interleukin 12 ◽  
Pcr Analysis ◽  
Human Macrophage ◽  
Ifn Γ

ABSTRACT Mycobacterium tuberculosis is an intracellular pathogen that readily survives and replicates in human macrophages (MΦ). Host cells have developed different mycobactericidal mechanisms, including the production of inflammatory cytokines. The aim of this study was to compare the MΦ response, in terms of cytokine gene expression, to infection with the M. tuberculosis laboratory strain H37Rv and the clinical M. tuberculosis isolate CMT97. Both strains induce the production of interleukin-12 (IL-12) and IL-16 at comparable levels. However, the clinical isolate induces a significantly higher and more prolonged MΦ activation, as shown by reverse transcription-PCR analysis of IL-1β, IL-6, IL-10, transforming growth factor beta, tumor necrosis factor alpha, and gamma interferon (IFN-γ) transcripts. Interestingly, when IFN-γ transcription is high, the number of M. tuberculosis genes expressed decreases and vice versa, whereas no mycobactericidal effect was observed in terms of bacterial growth. Expression of 11 genes was also studied in the two M. tuberculosis strains by infecting resting or activated MΦ and compared to bacterial intracellular survival. In both cases, a peculiar inverse correlation between expression of these genes and multiplication was observed. The number and type of genes expressed by the two strains differed significantly.

scholarly journals The novel Dbl homology/BAR domain protein, MsgA, of Talaromyces marneffei regulates yeast morphogenesis during growth inside host cells

2018 ◽  
Author(s):  
Harshini Weerasinghe ◽  
Hayley E. Bugeja ◽  
Alex Andrianopoulos
Keyword(s):  
Pathogenic Fungi ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Mammalian Host ◽  
Host Immune System ◽  
Nucleotide Exchange ◽  
Phagocytic Cells ◽  
Macrophage Infection ◽  
Bar Domain ◽  
Talaromyces Marneffei

AbstractMicrobial pathogens have evolved many strategies to evade recognition by the host immune system, including the use of phagocytic cells as a niche within which to proliferate. Dimorphic pathogenic fungi employ an induced morphogenetic transition, switching from multicellular hyphae to unicellular yeast that are more compatible with intracellular growth. A switch to mammalian host body temperature (37°C) is a key trigger for the dimorphic switch. This study describes a novel gene, msgA, from the dimorphic fungal pathogen Talaromyces marneffei that controls cell morphology in response to host cues rather than temperature. The msgA gene is upregulated during murine macrophage infection, and deletion results in aberrant yeast morphology solely during growth inside macrophages. MsgA contains a Dbl homology domain, and a Bin, Amphiphysin, Rvs (BAR) domain instead of a Plekstrin homology domain typically associated with guanine nucleotide exchange factors (GEFs). The BAR domain is crucial in maintaining yeast morphology and cellular localisation during infection. The data suggests that MsgA does not act as a canonical GEF during macrophage infection and identifies a temperature independent pathway in T. marneffei that controls intracellular yeast morphogenesis.

scholarly journals Mycobacterium tuberculosis Cpn60.2 and DnaK Are Located on the Bacterial Surface, Where Cpn60.2 Facilitates Efficient Bacterial Association with Macrophages

2009 ◽  
Vol 77 (8) ◽  
pp. 3389-3401 ◽  
Author(s):  
Tyler B. M. Hickey ◽  
Lisa M. Thorson ◽  
David P. Speert ◽  
Mamadou Daffé ◽  
Richard W. Stokes
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Molecular Chaperones ◽  
Polyacrylamide Gel Electrophoresis ◽  
Host Cells ◽  
Outer Cell ◽  
Dependent Manner ◽  
Bacterial Surface ◽  
Bacterial Binding ◽  
Capsular Material ◽  
Bacterial Association

ABSTRACT Mycobacterium tuberculosis, the causative agent of tuberculosis, initially contacts host cells with elements of its outer cell wall, or capsule. We have shown that capsular material from the surface of M. tuberculosis competitively inhibits the nonopsonic binding of whole M. tuberculosis bacilli to macrophages in a dose-dependent manner that is not acting through a global inhibition of macrophage binding. We have further demonstrated that isolated M. tuberculosis capsular proteins mediate a major part of this inhibition. Two-dimensional polyacrylamide gel electrophoresis analysis of the capsular proteins showed the presence of a wide variety of protein species, including proportionately high levels of the Cpn60.2 (Hsp65, GroEL2) and DnaK (Hsp70) molecular chaperones. Both of these proteins were subsequently detected on the bacterial surface. To determine whether these molecular chaperones play a role in bacterial binding, recombinant Cpn60.2 and DnaK were tested for their ability to inhibit the association of M. tuberculosis bacilli with macrophages. We found that recombinant Cpn60.2 can inhibit ∼57% of bacterial association with macrophages, while DnaK was not inhibitory at comparable concentrations. Additionally, when polyclonal F(ab′)2 fragments of anti-Cpn60.2 and anti-DnaK were used to mask the surface presentation of these molecular chaperones, a binding reduction of ∼34% was seen for anti-Cpn60.2 F(ab′)2, while anti-DnaK F(ab′)2 did not significantly reduce bacterial association with macrophages. Thus, our findings suggest that while M. tuberculosis displays both surface-associated Cpn60.2 and DnaK, only Cpn60.2 demonstrates adhesin functionality with regard to macrophage interaction.

scholarly journals Evolutionary Genetics of Mycobacterium tuberculosis and HIV-1: “The Tortoise and the Hare”

2021 ◽  
Vol 9 (1) ◽  
pp. 147
Author(s):  
Ana Santos-Pereira ◽  
Carlos Magalhães ◽  
Pedro M. M. Araújo ◽  
Nuno S. Osório
Keyword(s):  
Genetic Diversity ◽  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Evolutionary Dynamics ◽  
Evolutionary Genetics ◽  
Host Cells ◽  
Whole Genome Sequencing Data ◽  
Host Immune System ◽  
Viral Mutant ◽  
Hiv 1

The already enormous burden caused by Mycobacterium tuberculosis and Human Immunodeficiency Virus type 1 (HIV-1) alone is aggravated by co-infection. Despite obvious differences in the rate of evolution comparing these two human pathogens, genetic diversity plays an important role in the success of both. The extreme evolutionary dynamics of HIV-1 is in the basis of a robust capacity to evade immune responses, to generate drug-resistance and to diversify the population-level reservoir of M group viral subtypes. Compared to HIV-1 and other retroviruses, M. tuberculosis generates minute levels of genetic diversity within the host. However, emerging whole-genome sequencing data show that the M. tuberculosis complex contains at least nine human-adapted phylogenetic lineages. This level of genetic diversity results in differences in M. tuberculosis interactions with the host immune system, virulence and drug resistance propensity. In co-infected individuals, HIV-1 and M. tuberculosis are likely to co-colonize host cells. However, the evolutionary impact of the interaction between the host, the slowly evolving M. tuberculosis bacteria and the HIV-1 viral “mutant cloud” is poorly understood. These evolutionary dynamics, at the cellular niche of monocytes/macrophages, are also discussed and proposed as a relevant future research topic in the context of single-cell sequencing.

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