scholarly journals Multiscale Model of Mycobacterium tuberculosis Infection Maps Metabolite and Gene Perturbations to Granuloma Sterilization Predictions

2016 ◽  
Vol 84 (5) ◽  
pp. 1650-1669 ◽  
Author(s):  
Elsje Pienaar ◽  
William M. Matern ◽  
Jennifer J. Linderman ◽  
Joel S. Bader ◽  
Denise E. Kirschner
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Host Immunity ◽  
New Drugs ◽  
Metabolic Enzyme ◽  
Adaptation To Hypoxia ◽  
Mycobacterium Tuberculosis Infection ◽  
Lipid Inclusion ◽  
Content Type ◽  
The Impact

Granulomas are a hallmark of tuberculosis. Inside granulomas, the pathogenMycobacterium tuberculosismay enter a metabolically inactive state that is less susceptible to antibiotics. UnderstandingM. tuberculosismetabolism within granulomas could contribute to reducing the lengthy treatment required for tuberculosis and provide additional targets for new drugs. Two key adaptations ofM. tuberculosisare a nonreplicating phenotype and accumulation of lipid inclusions in response to hypoxic conditions. To explore how these adaptations influence granuloma-scale outcomesin vivo, we present a multiscalein silicomodel of granuloma formation in tuberculosis. The model comprises host immunity,M. tuberculosismetabolism,M. tuberculosisgrowth adaptation to hypoxia, and nutrient diffusion. We calibrated our model toin vivodata from nonhuman primates and rabbits and apply the model to predictM. tuberculosispopulation dynamics and heterogeneity within granulomas. We found that bacterial populations are highly dynamic throughout infection in response to changing oxygen levels and host immunity pressures. Our results indicate that a nonreplicating phenotype, but not lipid inclusion formation, is important for long-termM. tuberculosissurvival in granulomas. We used virtualM. tuberculosisknockouts to predict the impact of both metabolic enzyme inhibitors and metabolic pathways exploited to overcome inhibition. Results indicate that knockouts whose growth rates are below ∼66% of the wild-type growth rate in a culture medium featuring lipid as the only carbon source are unable to sustain infections in granulomas. By mapping metabolite- and gene-scale perturbations to granuloma-scale outcomes and predicting mechanisms of sterilization, our method provides a powerful tool for hypothesis testing and guiding experimental searches for novel antituberculosis interventions.

scholarly journals Developing New Drugs for Mycobacterium tuberculosis Therapy: What Information Do We Get from Preclinical Animal Models?

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
G. L. Drusano ◽  
Brandon Duncanson ◽  
C. A. Scanga ◽  
S. Kim ◽  
S. Schmidt ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Animal Models ◽  
Scale Up ◽  
New Drugs ◽  
Model Systems ◽  
Infection Model ◽  
New Agents ◽  
Content Type ◽  
Preclinical Animal Models ◽  
The Impact

ABSTRACT Preclinical animal models of infection are employed to develop new agents but also to screen among molecules to rank them. There are often major differences between human pharmacokinetic (PK) profiles and those developed by animal models of infection, and these may lead to substantial differences in efficacy relative to that seen in humans. Linezolid is a repurposed agent employed to great effect for therapy of Mycobacterium tuberculosis. In this study, we used the hollow-fiber infection model (HFIM) to evaluate the impact of different pharmacokinetic profiles of mice and nonhuman primates (NHP) versus humans on bacterial cell kill as well as resistance suppression. We examined both plasma and epithelial lining fluid (ELF) profiles. We examined simulated exposures equivalent to 600 mg and 900 mg daily of linezolid in humans. For both plasma and ELF exposures, the murine PK profile provided estimates of effect that were biased low relative to human and NHP PK profiles. Mathematical modeling identified a linkage between minimum concentrations (Cmin) and bacterial kill and peak concentrations (Cpeak) and resistance suppression, with the latter being supported by a prospective validation study. Finding new agents with novel mechanisms of action against M. tuberculosis is difficult. It would be a tragedy to discard a new agent because of a biased estimate of effect in a preclinical animal system. The HFIM provides a system to benchmark evaluation of new compounds in preclinical animal model systems against human PK effects (species scale-up estimates of PK), to safeguard against unwarranted rejection of promising new agents.

scholarly journals The Endothelin System Has a Significant Role in the Pathogenesis and Progression of Mycobacterium tuberculosis Infection

2014 ◽  
Vol 82 (12) ◽  
pp. 5154-5165 ◽  
Author(s):  
Andre F. Correa ◽  
Alexandre M. Bailão ◽  
Izabela M. D. Bastos ◽  
Ian M. Orme ◽  
Célia M. A. Soares ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Tuberculosis Infection ◽  
Content Type ◽  
Host Interactions ◽  
Endothelin System ◽  
Etb Receptor ◽  
The Impact ◽  
The Relationship ◽  
Host Tissues

ABSTRACTTuberculosis (TB) remains a major global health problem, and although multiple studies have addressed the relationship betweenMycobacterium tuberculosisand the host on an immunological level, few studies have addressed the impact of host physiological responses. Proteases produced by bacteria have been associated with important alterations in the host tissues, and a limited number of these enzymes have been characterized in mycobacterial species.M. tuberculosisproduces a protease called Zmp1, which appears to be associated with virulence and has a putative action as an endothelin-converting enzyme. Endothelins are a family of vasoactive peptides, of which 3 distinct isoforms exist, and endothelin 1 (ET-1) is the most abundant and the best-characterized isoform. The aim of this work was to characterize the Zmp1 protease and evaluate its role in pathogenicity. Here, we have shown thatM. tuberculosisproduces and secretes an enzyme with ET-1 cleavage activity. These data demonstrate a possible role of Zmp1 for mycobacterium-host interactions and highlights its potential as a drug target. Moreover, the results suggest that endothelin pathways have a role in the pathogenesis ofM. tuberculosisinfections, and ETA or ETB receptor signaling can modulate the host response to the infection. We hypothesize that a balance between Zmp1 control of ET-1 levels and ETA/ETB signaling can allowM. tuberculosisadaptation and survival in the lung tissues.

scholarly journals Adaptation of Mycobacterium tuberculosis to Impaired Host Immunity in HIV-Infected Patients

2016 ◽  
Vol 214 (8) ◽  
pp. 1205-1211 ◽  
Author(s):  
Nicholas D. Walter ◽  
Bouke C. de Jong ◽  
Benjamin J. Garcia ◽  
Gregory M. Dolganov ◽  
William Worodria ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Alternative Pathway ◽  
Acid Fast Bacillus ◽  
Host Immunity ◽  
Immune Genes ◽  
Human Genes ◽  
Dosr Regulon ◽  
The Impact ◽  
Lower Expression

AbstractBackground.  It is unknown whether immunosuppression influences the physiologic state of Mycobacterium tuberculosis in vivo. We evaluated the impact of host immunity by comparing M. tuberculosis and human gene transcription in sputum between human immunodeficiency virus (HIV)–infected and uninfected patients with tuberculosis.Methods.  We collected sputum specimens before treatment from Gambians and Ugandans with pulmonary tuberculosis, revealed by positive results of acid-fast bacillus smears. We quantified expression of 2179 M. tuberculosis genes and 234 human immune genes via quantitative reverse transcription–polymerase chain reaction. We summarized genes from key functional categories with significantly increased or decreased expression.Results.  A total of 24 of 65 patients with tuberculosis were HIV infected. M. tuberculosis DosR regulon genes were less highly expressed among HIV-infected patients with tuberculosis than among HIV-uninfected patients with tuberculosis (Gambia, P < .0001; Uganda, P = .037). In profiling of human genes from the same sputa, HIV-infected patients had 3.4-fold lower expression of IFNG (P = .005), 4.9-fold higher expression of ARG1 (P = .0006), and 3.4-fold higher expression of IL10 (P = .0002) than in HIV-uninfected patients with tuberculosis.Conclusions.  M. tuberculosis in HIV-infected patients had lower expression of the DosR regulon, a critical metabolic and immunomodulatory switch induced by NO, carbon monoxide, and hypoxia. Our human data suggest that decreased DosR expression may result from alternative pathway activation of macrophages, with consequent decreased NO expression and/or by poor granuloma formation with consequent decreased hypoxic stress.

scholarly journals Gut Microbiota Metabolite Indole Propionic Acid Targets Tryptophan Biosynthesis in Mycobacterium tuberculosis

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Dereje Abate Negatu ◽  
Yoshiyuki Yamada ◽  
Yu Xi ◽  
Mei Lin Go ◽  
Matthew Zimmerman ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Gut Microbiota ◽  
Propionic Acid ◽  
De Novo ◽  
Feedback Inhibition ◽  
New Drugs ◽  
Anthranilate Synthase ◽  
Content Type ◽  
Allosteric Inhibitor

ABSTRACT Indole propionic acid (IPA), produced by the gut microbiota, is active against Mycobacterium tuberculosis in vitro and in vivo. However, its mechanism of action is unknown. IPA is the deamination product of tryptophan (Trp) and thus a close structural analog of this essential aromatic amino acid. De novo Trp biosynthesis in M. tuberculosis is regulated through feedback inhibition: Trp acts as an allosteric inhibitor of anthranilate synthase TrpE, which catalyzes the first committed step in the Trp biosynthesis pathway. Hence, we hypothesized that IPA may mimic Trp as an allosteric inhibitor of TrpE and exert its antimicrobial effect by blocking synthesis of Trp at the TrpE catalytic step. To test our hypothesis, we carried out metabolic, chemical rescue, genetic, and biochemical analyses. Treatment of mycobacteria with IPA inhibited growth and reduced the intracellular level of Trp, an effect abrogated upon supplementation of Trp in the medium. Missense mutations at the allosteric Trp binding site of TrpE eliminated Trp inhibition and caused IPA resistance. In conclusion, we have shown that IPA blocks Trp biosynthesis in M. tuberculosis via inhibition of TrpE by mimicking the physiological allosteric inhibitor of this enzyme. IMPORTANCE New drugs against tuberculosis are urgently needed. The tryptophan (Trp) analog indole propionic acid (IPA) is the first antitubercular metabolite produced by human gut bacteria. Here, we show that this antibiotic blocks Trp synthesis, an in vivo essential biosynthetic pathway in M. tuberculosis. Intriguingly, IPA acts by decoupling a bacterial feedback regulatory mechanism: it mimics Trp as allosteric inhibitor of anthranilate synthase, thereby switching off Trp synthesis regardless of intracellular Trp levels. The identification of IPA’s target paves the way for the discovery of more potent TrpE ligands employing rational, target-based lead optimization.

scholarly journals The Combination of Sulfamethoxazole, Trimethoprim, and Isoniazid or Rifampin Is Bactericidal and Prevents the Emergence of Drug Resistance in Mycobacterium tuberculosis

2012 ◽  
Vol 56 (10) ◽  
pp. 5142-5148 ◽  
Author(s):  
Catherine Vilchèze ◽  
William R. Jacobs
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Multidrug Resistant ◽  
New Drugs ◽  
Drug Resistant ◽  
Content Type ◽  
The Past ◽  
Tb Treatment

ABSTRACTThe challenges of developing new drugs to treat tuberculosis (TB) are indicated by the relatively small number of candidates entering clinical trials in the past decade. To overcome these issues, we reexamined two FDA-approved antibacterial drugs, sulfamethoxazole (SMX) and trimethoprim (TMP), for use in TB treatment. SMX and TMP inhibit folic acid biosynthesis and are used in combination to treat infections of the respiratory, urinary, and gastrointestinal tracts. The MICs of SMX and TMP, alone and in combination, were determined for drug-susceptible, multidrug-resistant (MDR), and extensively drug-resistantMycobacterium tuberculosisstrains. While TMP alone was not effective againstM. tuberculosis, the combination of TMP and SMX was bacteriostatic againstM. tuberculosis. Surprisingly, the combination of SMX and TMP was also active against a subset of MDRM. tuberculosisstrains. Treatment ofM. tuberculosiswith TMP-SMX and a first-line anti-TB drug, either isoniazid or rifampin, was bactericidal, demonstrating that the combination of TMP and SMX with isoniazid or rifampin was not antagonistic. Moreover, the addition of SMX-TMP in combination with either isoniazid or rifampin also prevented the emergence of drug resistancein vitro. In conclusion, this study further illustrates the opportunity to reevaluate the activity of TMP-SMXin vivoto prevent the emergence of drug-resistantM. tuberculosis.

scholarly journals Killer Cell Lectin-Like Receptor G1 Deficiency Significantly Enhances Survival after Mycobacterium tuberculosis Infection

2013 ◽  
Vol 81 (4) ◽  
pp. 1090-1099 ◽  
Author(s):  
Joshua C. Cyktor ◽  
Bridget Carruthers ◽  
Paul Stromberg ◽  
Emilio Flaño ◽  
Hanspeter Pircher ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Differentiation ◽  
T Cell ◽  
Killer Cell ◽  
T Cell Differentiation ◽  
Mycobacterium Tuberculosis Infection ◽  
Differentiation Markers ◽  
Content Type ◽  
Differentiation Marker

ABSTRACTThe expression of T cell differentiation markers is known to increase duringMycobacterium tuberculosisinfection, and yet the biological role of such markers remains unclear. We examined the requirement of the T cell differentiation marker killer cell lectin-like receptor G1 (KLRG1) duringM. tuberculosisinfection using mice deficient in KLRG1. KLRG1−/−mice had a significant survival extension afterM. tuberculosisinfection compared to wild-type controls, and maintained a significantly lower level of pulmonaryM. tuberculosisthroughout chronic infection. Improved control ofM. tuberculosisinfection was associated with an increased number of activated pulmonary CD4+T cells capable of secreting gamma interferon (IFN-γ). Our report is the first to show anin vivoimpact of KLRG1 on disease control.

scholarly journals The Lung Mucosa Environment in the Elderly Increases Host Susceptibility to Mycobacterium tuberculosis Infection

2019 ◽  
Vol 220 (3) ◽  
pp. 514-523 ◽  
Author(s):  
Juan I Moliva ◽  
Michael A Duncan ◽  
Angélica Olmo-Fontánez ◽  
Anwari Akhter ◽  
Eusondia Arnett ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
The Elderly ◽  
Surfactant Protein ◽  
Host Susceptibility ◽  
Surfactant Protein D ◽  
Mycobacterium Tuberculosis Infection ◽  
Increased Risk ◽  
The Impact

AbstractAs we age, there is an increased risk for the development of tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection. Few studies consider that age-associated changes in the alveolar lining fluid (ALF) may increase susceptibility by altering soluble mediators of innate immunity. We assessed the impact of adult or elderly human ALF during Mtb infection in vitro and in vivo. We identified amplification of pro-oxidative and proinflammatory pathways in elderly ALF and decreased binding capability of surfactant-associated surfactant protein A (SP-A) and surfactant protein D (SP-D) to Mtb. Human macrophages infected with elderly ALF–exposed Mtb had reduced control and fewer phagosome–lysosome fusion events, which was reversed when elderly ALF was replenished with functional SP-A/SP-D. In vivo, exposure to elderly ALF exacerbated Mtb infection in young mice. Our studies demonstrate how the pulmonary environment changes as we age and suggest that Mtb may benefit from declining host defenses in the lung mucosa of the elderly.

scholarly journals Three-dimensional in situ morphometrics of Mycobacterium tuberculosis infection within lesions by optical mesoscopy and novel acid-fast staining

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Robert J. Francis ◽  
Gillian Robb ◽  
Lee McCann ◽  
Bhagwati Khatri ◽  
James Keeble ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Three Dimensional ◽  
Large Field ◽  
Staining Procedure ◽  
3D Analysis ◽  
Mycobacterium Tuberculosis Infection ◽  
In Vivo Models ◽  
Novel Approach

AbstractTuberculosis (TB) preclinical testing relies on in vivo models including the mouse aerosol challenge model. The only method of determining colony morphometrics of TB infection in a tissue in situ is two-dimensional (2D) histopathology. 2D measurements consider heterogeneity within a single observable section but not above and below, which could contain critical information. Here we describe a novel approach, using optical clearing and a novel staining procedure with confocal microscopy and mesoscopy, for three-dimensional (3D) measurement of TB infection within lesions at sub-cellular resolution over a large field of view. We show TB morphometrics can be determined within lesion pathology, and differences in infection with different strains of Mycobacterium tuberculosis. Mesoscopy combined with the novel CUBIC Acid-Fast (CAF) staining procedure enables a quantitative approach to measure TB infection and allows 3D analysis of infection, providing a framework which could be used in the analysis of TB infection in situ.

scholarly journals Exogenous Alginate Protects Staphylococcus aureus from Killing by Pseudomonas aeruginosa

2019 ◽  
Vol 202 (8) ◽  
Author(s):  
Courtney E. Price ◽  
Dustin G. Brown ◽  
Dominique H. Limoli ◽  
Vanessa V. Phelan ◽  
George A. O’Toole
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Physical Space ◽  
Late Time ◽  
Protective Effects ◽  
Content Type ◽  
Alginate Production ◽  
The Impact

ABSTRACT Cystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are monoinfected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can coexist with S. aureus in vitro due to the transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here, we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm coculture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to the transcriptional downregulation of pvdA, a gene required for the production of the iron-scavenging siderophore pyoverdine as well as the downregulation of the PQS (Pseudomonas quinolone signal) (2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that coculture of mucoid P. aeruginosa with nonmucoid P. aeruginosa strains can mitigate the killing of S. aureus by the nonmucoid strain of P. aeruginosa, indicating that the mechanism that we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability to kill S. aureus at late time points and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the S. aureus-protective effects of mucoidy in a strain-specific manner. IMPORTANCE CF patients are chronically infected by polymicrobial communities. The two dominant bacterial pathogens that infect the lungs of CF patients are P. aeruginosa and S. aureus, with ∼30% of patients coinfected by both species. Such coinfected individuals have worse outcomes than monoinfected patients, and both species persist within the same physical space. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus coexistence, despite evidence that P. aeruginosa kills S. aureus when these organisms are cocultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to coexist in proximal physical space, will lead to better-informed treatments for chronic polymicrobial infections.

scholarly journals Neither Primary nor Memory Immunity to Mycobacterium tuberculosis Infection Is Compromised in Mice with Chronic Enteric Helminth Infection

2015 ◽  
Vol 83 (3) ◽  
pp. 1217-1223 ◽  
Author(s):  
Wasiulla Rafi ◽  
Kamlesh Bhatt ◽  
William C. Gause ◽  
Padmini Salgame
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Regulatory Cells ◽  
Helminth Infection ◽  
Treg Cells ◽  
Helminth Species ◽  
Nippostrongylus Brasiliensis ◽  
T Regulatory Cell ◽  
Chronic Infections ◽  
Mycobacterium Tuberculosis Infection ◽  
Content Type

Previously we had reported thatNippostrongylus brasiliensis, a helminth with a lung migratory phase, affected host resistance againstMycobacterium tuberculosisinfection through the induction of alternatively activated (M2) macrophages. Several helminth species do not have an obligatory lung migratory phase but establish chronic infections in the host that include potent immune downregulatory effects, in part mediated through induction of a FoxP3+T regulatory cell (Treg) response. Treg cells exhibit duality in their functions in host defense againstM. tuberculosisinfection since their depletion leads to enhanced priming of T cells in the lymph nodes and attendant improved control ofM. tuberculosisinfection, while their presence in the lung granuloma protects against excessive inflammation.Heligmosomoides polygyrusis a strictly murine enteric nematode that induces a strong FoxP3 Treg response in the host. Therefore, in this study we investigated whether host immunity toM. tuberculosisinfection would be modulated in mice with chronicH. polygyrusinfection. We report that neither primary nor memory immunity conferred byMycobacterium bovisBCG vaccination was affected in mice with chronic enteric helminth infection, despite a systemic increase in FoxP3+T regulatory cells. The findings indicate that anti-M. tuberculosisimmunity is not similarly affected by all helminth species and highlight the need to consider this inequality in human coinfection studies.

Sign in / Sign up

Export Citation Format

Share Document