scholarly journals Evaluation of a Mouse Model of Necrotic Granuloma Formation Using C3HeB/FeJ Mice for Testing of Drugs against Mycobacterium tuberculosis

2012 ◽  
Vol 56 (6) ◽  
pp. 3181-3195 ◽  
Author(s):  
Emily R. Driver ◽  
Gavin J. Ryan ◽  
Donald R. Hoff ◽  
Scott M. Irwin ◽  
Randall J. Basaraba ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Drug Therapy ◽  
Mouse Model ◽  
Bacterial Load ◽  
Lung Lesions ◽  
Content Type ◽  
Liquefactive Necrosis ◽  
Progression Of Disease ◽  
Staining Techniques ◽  
Late Stages

ABSTRACTPersistence ofMycobacterium tuberculosisremains a significant challenge for the effective treatment of tuberculosis in humans. In animals that develop necrotic lung lesions following infection withM. tuberculosis, drug-tolerant bacilli are present and persist in an extracellular microenvironment within the necrotic cores. In this study, we examined the efficacy of drug treatment in C3HeB/FeJ (Kramnik) mice that develop lesions with liquefactive necrosis, in comparison to BALB/c mice that develop nonnecrotic lesions following aerosol challenge. To accomplish this, Kramnik and BALB/c mice were infected by aerosol withM. tuberculosisand treated for 7 to 8 weeks with monotherapy using drugs with different modes of action. The efficacy of drug therapy was quantified by enumeration of bacterial load. The progression of disease and location and distribution of bacilli within lesions were visualized using various staining techniques. In the late stages of infection, Kramnik mice developed fibrous encapsulated lung lesions with central liquefactive necrosis containing abundant extracellular bacilli, whereas BALB/c mice formed nonnecrotic lesions with primarily intracellular bacilli. Necrotic lesions in Kramnik mice showed evidence of hypoxia by pimonidazole staining. Kramnik mice were significantly more refractory to drug therapy, especially for pyrazinamide. Metronidazole showed no bactericidal activity in either model. There were significantly higher numbers of drug-resistant colonies isolated from the Kramnik mice compared to BALB/c mice. These results suggest that the Kramnik mouse model will be a valuable model to test antituberculosis drugs, especially against bacilli that persist within necrotic lesions.

scholarly journals Efficacy and Improved Resistance Potential of a Cofactor-Independent InhA Inhibitor of Mycobacterium tuberculosis in the C3HeB/FeJ Mouse Model

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
Gregory T. Robertson ◽  
Victoria A. Ektnitphong ◽  
Michael S. Scherman ◽  
Matthew B. McNeil ◽  
Devon Dennison ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mouse Model ◽  
Promising Alternative ◽  
Lung Lesions ◽  
Content Type ◽  
Drug Levels ◽  
Lower Resistance ◽  
Inha Inhibitor

ABSTRACT AN12855 is a direct, cofactor-independent inhibitor of InhA in Mycobacterium tuberculosis. In the C3HeB/FeJ mouse model with caseous necrotic lung lesions, AN12855 proved efficacious with a significantly lower resistance frequency than isoniazid. AN12855 drug levels were better retained in necrotic lesions and caseum where the majority of hard to treat, extracellular bacilli reside. Owing to these combined attributes, AN12855 represents a promising alternative to the frontline antituberculosis agent isoniazid.

scholarly journals Monitoring Tuberculosis Drug Activity in Live Animals by Using Near-Infrared Fluorescence Imaging

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
Raphael Sommer ◽  
Stewart T. Cole
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Near Infrared ◽  
Imaging System ◽  
Limit Of Detection ◽  
Bacterial Load ◽  
Genetically Engineered ◽  
Fluorescent Imaging ◽  
Effective Vaccine ◽  
Content Type ◽  
Immunodeficient Mice

ABSTRACT Worldwide, tuberculosis (TB) is the leading cause of death due to infection with a single pathogenic agent, Mycobacterium tuberculosis. In the absence of an effective vaccine, new, more powerful antibiotics are required to halt the growing spread of multidrug-resistant strains and to shorten the duration of TB treatment. However, assessing drug efficacy at the preclinical stage remains a long and fastidious procedure that delays the progression of drugs down the pipeline and towards the clinic. In this investigation, we report the construction, optimization, and characterization of genetically engineered near-infrared (NIR) fluorescent reporter strains of the pathogens Mycobacterium marinum and Mycobacterium tuberculosis that enable the direct visualization of bacteria in infected zebrafish and mice, respectively. Fluorescence could be measured precisely in infected immunodeficient mice, while its intensity appeared to be below the limit of detection in immunocompetent mice, probably because of the lower bacterial load obtained in these animals. Furthermore, we show that the fluorescence level accurately reflects the bacterial load, as determined by CFU enumeration, thus enabling the efficacy of antibiotic treatment to be assessed in live animals in real time. The NIR fluorescent imaging system disclosed here is a valuable resource for TB research and can serve to accelerate drug development.

scholarly journals Efficient 5-OP-RU-Induced Enrichment of Mucosa-Associated Invariant T Cells in the Murine Lung Does Not Enhance Control of Aerosol Mycobacterium tuberculosis Infection

2020 ◽  
Vol 89 (1) ◽  
pp. e00524-20 ◽  
Author(s):  
Charles Kyriakos Vorkas ◽  
Olivier Levy ◽  
Miroslav Skular ◽  
Kelin Li ◽  
Jeffrey Aubé ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Bacterial Infections ◽  
Cell Activation ◽  
Bacterial Load ◽  
Cell Subset ◽  
Mycobacterium Tuberculosis Infection ◽  
Class I Mhc ◽  
Content Type ◽  
Mait Cells ◽  
Mait Cell

ABSTRACTMucosa-associated invariant T (MAIT) cells are an innate-like T cell subset in mammals that recognize microbial vitamin B metabolites presented by the evolutionarily conserved major histocompatibility complex class I (MHC I)-related molecule, MR1. Emerging data suggest that MAIT cells may be an attractive target for vaccine-induced protection against bacterial infections because of their rapid cytotoxic responses at mucosal services to a widely conserved bacterial ligand. In this study, we tested whether a MAIT cell priming strategy could protect against aerosol Mycobacterium tuberculosis infection in mice. Intranasal costimulation with the lipopeptide Toll-like receptor (TLR)2/6 agonist, Pam2Cys (P2C), and the synthetic MR1 ligand, 5-OP-RU, resulted in robust expansion of MAIT cells in the lung. Although MAIT cell priming significantly enhanced MAIT cell activation and expansion early after M. tuberculosis challenge, these MAIT cells did not restrict M. tuberculosis bacterial load. MAIT cells were depleted by the onset of the adaptive immune response, with decreased detection of granzyme B+ and gamma interferon (IFN-γ)+ MAIT cells relative to that in uninfected P2C/5-OP-RU-treated mice. Decreasing the infectious inoculum, varying the time between priming and aerosol infection, and testing MAIT cell priming in nitric oxide synthase 2 (NOS2)-deficient mice all failed to reveal an effect of P2C/5-OP-RU-induced MAIT cells on M. tuberculosis control. We conclude that intranasal MAIT cell priming in mice induces early MAIT cell activation and expansion after M. tuberculosis exposure, without attenuating M. tuberculosis growth, suggesting that MAIT cell enrichment in the lung is not sufficient to control M. tuberculosis infection.

scholarly journals Mycobacterium tuberculosis Lsr2 Is a Global Transcriptional Regulator Required for Adaptation to Changing Oxygen Levels and Virulence

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
I. L. Bartek ◽  
L. K. Woolhiser ◽  
A. D. Baughn ◽  
R. J. Basaraba ◽  
W. R. Jacobs ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mouse Model ◽  
Oxygen Tension ◽  
Reactive Oxygen ◽  
Transcriptional Regulator ◽  
Oxygen Availability ◽  
World Population ◽  
Lung Pathology ◽  
Content Type ◽  
Oxygen Levels

ABSTRACTTo survive a dynamic host environment,Mycobacterium tuberculosismust endure a series of challenges, from reactive oxygen and nitrogen stress to drastic shifts in oxygen availability. The mycobacterial Lsr2 protein has been implicated in reactive oxygen defense via direct protection of DNA. To examine the role of Lsr2 in pathogenesis and physiology ofM. tuberculosis, we generated a strain deleted forlsr2. Analysis of theM. tuberculosisΔlsr2strain demonstrated that Lsr2 is not required for DNA protection, as this strain was equally susceptible as the wild type to DNA-damaging agents. Thelsr2mutant did display severe growth defects under normoxic and hyperoxic conditions, but it was not required for growth under low-oxygen conditions. However, it was also required for adaptation to anaerobiosis. The defect in anaerobic adaptation led to a marked decrease in viability during anaerobiosis, as well as a lag in recovery from it. Gene expression profiling of the Δlsr2mutant under aerobic and anaerobic conditions in conjunction with published DNA binding-site data indicates that Lsr2 is a global transcriptional regulator controlling adaptation to changing oxygen levels. The Δlsr2strain was capable of establishing an early infection in the BALB/c mouse model; however, it was severely defective in persisting in the lungs and caused no discernible lung pathology. These findings demonstrateM. tuberculosisLsr2 is a global transcriptional regulator required for control of genes involved in adaptation to extremes in oxygen availability and is required for persistent infection.IMPORTANCEM. tuberculosiscauses nearly two million deaths per year and infects nearly one-third of the world population. The success of this aerobic pathogen is due in part to its ability to successfully adapt to constantly changing oxygen availability throughout the infectious cycle, from the high oxygen tension during aerosol transmission to anaerobiosis within necrotic lesions. An understanding of howM. tuberculosiscopes with these changes in oxygen tension is critical for its eventual eradication. Using a mutation inlsr2, we demonstrate that the Lsr2 protein present in all mycobacteria is a global transcriptional regulator in control of genes required for adaptation to changes in oxygen levels.M. tuberculosislackinglsr2was unable to adapt to both high and very low levels of oxygen and was defective in long-term anaerobic survival. Lsr2 was also required for disease pathology and for chronic infection in a mouse model of TB.

scholarly journals Mode of Action of Clofazimine and Combination Therapy with Benzothiazinones against Mycobacterium tuberculosis

2015 ◽  
Vol 59 (8) ◽  
pp. 4457-4463 ◽  
Author(s):  
Benoit Lechartier ◽  
Stewart T. Cole
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Bacterial Load ◽  
Multidrug Resistant ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Drug Resistant Strains ◽  
Transfer Chain

ABSTRACTClofazimine (CZM) is an antileprosy drug that was recently repurposed for treatment of multidrug-resistant tuberculosis. InMycobacterium tuberculosis, CZM appears to act as a prodrug, which is reduced by NADH dehydrogenase (NDH-2), to release reactive oxygen species upon reoxidation by O2. CZM presumably competes with menaquinone (MK-4), a key cofactor in the mycobacterial electron transfer chain, for its reduction by NDH-2. We studied the effect of MK-4 supplementation on the activity of CZM againstM. tuberculosisand found direct competition between CZM and MK-4 for the cidal effect of CZM, against nonreplicating and actively growing bacteria, as MK-4 supplementation blocked the drug's activity against nonreplicating bacteria. We demonstrated that CZM, like bedaquiline, is synergisticin vitrowith benzothiazinones such as 2-piperazino-benzothiazinone 169 (PBTZ169), and this synergy also occurs against nonreplicating bacteria. The synergy between CZM and PBTZ169 was lost in an MK-4-rich medium, indicating that MK-4 is the probable link between their activities. The efficacy of the dual combination of CZM and PBTZ169 was testedin vivo, where a great reduction in bacterial load was obtained in a murine model of chronic tuberculosis. Taken together, these data confirm the potential of CZM in association with PBTZ169 as the basis for a new regimen against drug-resistant strains ofM. tuberculosis.

scholarly journals High Mycobacterium tuberculosis Bacillary Loads Detected by Tuberculosis Molecular Bacterial Load Assay in Patient Stool: a Potential Alternative for Nonsputum Diagnosis and Treatment Response Monitoring of Tuberculosis

2022 ◽  
Author(s):  
Emmanuel Musisi ◽  
Abdul Sessolo ◽  
Sylvia Kaswabuli ◽  
Josephine Zawedde ◽  
Patrick Byanyima ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Treatment Response ◽  
Bacterial Load ◽  
Diagnosis And Treatment ◽  
Response Monitoring ◽  
Sample Type ◽  
Content Type ◽  
Potential Alternative

This paper highlights the value of stool as a sample type for diagnosis of tuberculosis. While other studies have used DNA-based assays like the Xpert MTB/RIF and culture to detect Mycobacterium tuberculosis in stool, this is the first study that has applied TB-MBLA, an RNA-based assay, to quantify TB bacteria in stool.

scholarly journals New Evidence and Insights on Dalbavancin and Wound Healing in a Mouse Model of Skin Infection

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Oriana Simonetti ◽  
Guendalina Lucarini ◽  
Gianluca Morroni ◽  
Fiorenza Orlando ◽  
Raffaella Lazzarini ◽  
...  
Keyword(s):  
Wound Healing ◽  
Growth Factor ◽  
Mouse Model ◽  
Granulation Tissue ◽  
Skin Infection ◽  
Protein Extraction ◽  
Bacterial Load ◽  
Treated Group ◽  
Content Type ◽  
Matrix Metalloproteinase 1

ABSTRACT Dalbavancin is an effective antibiotic that is widely used to treat skin infection. Our aim was to determine the effect of dalbavancin administration on wound healing compared to that of vancomycin and to elucidate if epidermal growth factor receptor (EGFR), matrix metalloproteinase 1 (MMP-1), MMP-9, and vascular endothelial growth factor (VEGF) could be involved in its therapeutic mechanism. A mouse model of methicillin-resistant Staphylococcus aureus (MRSA) skin infection was established. Mice were treated daily with vancomycin (10 mg/kg) and weekly with dalbavancin at day 1 (20 mg/kg) and day 8 (10 mg/kg). After 14 days, wounds were excised, and bacterial counts were performed. Wound healing was assessed by histological and immunohistochemical staining, followed by protein extraction and immunoblotting. Our microbiological results confirmed that both dalbavancin and vancomycin are effective in reducing the bacterial load in wounds. The dalbavancin group showed a strong effect compared with infected untreated animals and the vancomycin-treated group. The wounds treated with dalbavancin showed robust epidermal coverage with reconstitution of the regular and keratinized epidermal lining and well-organized granulation tissue with numerous blood vessels, although slightly less than that in the uninfected group. While in the vancomycin-treated group the epithelium appeared, in general, still hypertrophic, the granulation tissue appeared even less organized. We observed elevated EGFR and VEGF expression in both treated groups, although it was higher in dalbavancin-treated mice. MMP-1 and MMP-9 were decreased in uninfected tissue and in both treated tissues compared with untreated infected wounds. This study showed faster healing with dalbavancin treatment that might be associated with higher EGFR and VEGF levels.

scholarly journals Deficiency of Double-Strand DNA Break Repair Does Not Impair Mycobacterium tuberculosis Virulence in Multiple Animal Models of Infection

2014 ◽  
Vol 82 (8) ◽  
pp. 3177-3185 ◽  
Author(s):  
Brook E. Heaton ◽  
Daniel Barkan ◽  
Paola Bongiorno ◽  
Petros C. Karakousis ◽  
Michael S. Glickman
Keyword(s):  
Dna Damage ◽  
Mycobacterium Tuberculosis ◽  
Animal Models ◽  
Bacterial Load ◽  
Dna Breaks ◽  
Dsb Repair ◽  
Content Type ◽  
Dna Break ◽  
Repair Systems ◽  
Double Strand Dna

ABSTRACTMycobacterium tuberculosispersistence within its human host requires mechanisms to resist the effector molecules of host immunity, which exert their bactericidal effects through damaging pathogen proteins, membranes, and DNA. Substantial evidence indicates that bacterial pathogens, includingM. tuberculosis, require DNA repair systems to repair the DNA damage inflicted by the host during infection, but the role of double-strand DNA break (DSB) repair systems is unclear. Double-strand DNA breaks are the most cytotoxic form of DNA damage and must be repaired for chromosome replication to proceed.M. tuberculosiselaborates three genetically distinct DSB repair systems: homologous recombination (HR), nonhomologous end joining (NHEJ), and single-strand annealing (SSA). NHEJ, which repairs DSBs in quiescent cells, may be particularly relevant toM. tuberculosislatency. However, very little information is available about the phenotype of DSB repair-deficientM. tuberculosisin animal models of infection. Here we testedM. tuberculosisstrains lacking NHEJ (a ΔkuΔligDstrain), HR (a ΔrecAstrain), or both (a ΔrecAΔkustrain) in C57BL/6J mice, C3HeB/FeJ mice, guinea pigs, and a mouse hollow-fiber model of infection. We found no difference in bacterial load, histopathology, or host mortality between wild-type and DSB repair mutant strains in any model of infection. These results suggest that the animal models tested do not inflict DSBs on the mycobacterial chromosome, that other repair pathways can compensate for the loss of NHEJ and HR, or that DSB repair is not required forM. tuberculosispathogenesis.

scholarly journals Mechanistic Modeling of Mycobacterium tuberculosis Infection in Murine Models for Drug and Vaccine Efficacy Studies

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Nan Zhang ◽  
Natasha Strydom ◽  
Sandeep Tyagi ◽  
Heena Soni ◽  
Rokeya Tasneen ◽  
...  
Keyword(s):  
Immune Response ◽  
Mycobacterium Tuberculosis ◽  
Vaccine Efficacy ◽  
Vaccine Development ◽  
Bacterial Load ◽  
Mechanistic Modeling ◽  
Response Dynamics ◽  
Content Type ◽  
Immune Effect ◽  
Adaptive Immune

ABSTRACT Tuberculosis (TB) drug, regimen, and vaccine development rely heavily on preclinical animal experiments, and quantification of bacterial and immune response dynamics is essential for understanding drug and vaccine efficacy. A mechanism-based model was built to describe Mycobacterium tuberculosis H37Rv infection over time in BALB/c and athymic nude mice, which consisted of bacterial replication, bacterial death, and adaptive immune effects. The adaptive immune effect was best described by a sigmoidal function on both bacterial load and incubation time. Applications to demonstrate the utility of this baseline model showed (i) the important influence of the adaptive immune response on pyrazinamide (PZA) drug efficacy, (ii) a persistent adaptive immune effect in mice relapsing after chemotherapy cessation, and (iii) the protective effect of vaccines after M. tuberculosis challenge. These findings demonstrate the utility of our model for describing M. tuberculosis infection and corresponding adaptive immune dynamics for evaluating the efficacy of TB drugs, regimens, and vaccines.

Sign in / Sign up

Export Citation Format

Share Document