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Microbiology Spectrum Jun 2024() as well as nontuberculous mycobacteria are intracellular pathogens whose treatment is extensive and increasingly impaired due to the rise of mycobacterial drug...
UNLABELLED
() as well as nontuberculous mycobacteria are intracellular pathogens whose treatment is extensive and increasingly impaired due to the rise of mycobacterial drug resistance. The loss of antibiotic efficacy has raised interest in the identification of host-directed therapeutics (HDT) to develop novel treatment strategies for mycobacterial infections. In this study, we identified amiodarone as a potential HDT candidate that inhibited both intracellular and in primary human macrophages without directly impairing bacterial growth, thereby confirming that amiodarone acts in a host-mediated manner. Moreover, amiodarone induced the formation of (auto)phagosomes and enhanced autophagic targeting of mycobacteria in macrophages. The induction of autophagy by amiodarone is likely due to enhanced transcriptional regulation, as the nuclear intensity of the transcription factor EB, the master regulator of autophagy and lysosomal biogenesis, was strongly increased. Furthermore, blocking lysosomal degradation with bafilomycin impaired the host-beneficial effect of amiodarone. Finally, amiodarone induced autophagy and reduced bacterial burden in a zebrafish embryo model of tuberculosis, thereby confirming the HDT activity of amiodarone . In conclusion, we have identified amiodarone as an autophagy-inducing antimycobacterial HDT that improves host control of mycobacterial infections.
IMPORTANCE
Due to the global rise in antibiotic resistance, there is a strong need for alternative treatment strategies against intracellular bacterial infections, including () and non-tuberculous mycobacteria. Stimulating host defense mechanisms by host-directed therapy (HDT) is a promising approach for treating mycobacterial infections. This study identified amiodarone, an antiarrhythmic agent, as a potential HDT candidate that inhibits the survival of and in primary human macrophages. The antimycobacterial effect of amiodarone was confirmed in an tuberculosis model based on infection of zebrafish embryos. Furthermore, amiodarone induced autophagy and inhibition of the autophagic flux effectively impaired the host-protective effect of amiodarone, supporting that activation of the host (auto)phagolysosomal pathway is essential for the mechanism of action of amiodarone. In conclusion, we have identified amiodarone as an autophagy-inducing HDT that improves host control of a wide range of mycobacteria.
PubMed: 38916320
DOI: 10.1128/spectrum.00167-24 -
ELife Jun 2024Tuberculosis is a major global health problem and is one of the top 10 causes of death worldwide. There is a pressing need for new treatments that circumvent emerging...
Tuberculosis is a major global health problem and is one of the top 10 causes of death worldwide. There is a pressing need for new treatments that circumvent emerging antibiotic resistance. parasitises macrophages, reprogramming them to establish a niche in which to proliferate, therefore macrophage manipulation is a potential host-directed therapy if druggable molecular targets could be identified. The pseudokinase Tribbles1 (Trib1) regulates multiple innate immune processes and inflammatory profiles making it a potential drug target in infections. Trib1 controls macrophage function, cytokine production, and macrophage polarisation. Despite wide-ranging effects on leukocyte biology, data exploring the roles of Tribbles in infection in vivo are limited. Here, we identify that human Tribbles1 is expressed in monocytes and is upregulated at the transcript level after stimulation with mycobacterial antigen. To investigate the mechanistic roles of Tribbles in the host response to mycobacteria in vivo, we used a zebrafish (Mm) infection tuberculosis model. Zebrafish Tribbles family members were characterised and shown to have substantial mRNA and protein sequence homology to their human orthologues. overexpression was host-protective against Mm infection, reducing burden by approximately 50%. Conversely, knockdown/knockout exhibited increased infection. Mechanistically, overexpression significantly increased the levels of proinflammatory factors and nitric oxide. The host-protective effect of was found to be dependent on the E3 ubiquitin kinase Cop1. These findings highlight the importance of Trib1 and Cop1 as immune regulators during infection in vivo and suggest that enhancing macrophage TRIB1 levels may provide a tractable therapeutic intervention to improve bacterial infection outcomes in tuberculosis.
Topics: Animals; Protein Serine-Threonine Kinases; Zebrafish; Humans; Intracellular Signaling Peptides and Proteins; Mycobacterium marinum; Disease Models, Animal; Mycobacterium Infections, Nontuberculous; Monocytes; Macrophages; Host-Pathogen Interactions
PubMed: 38896446
DOI: 10.7554/eLife.95980 -
Heliyon May 2024The emergence of multidrug-resistant mycobacterial strains is a significant crisis that has led to higher treatment failure rates and more toxic and expensive...
The emergence of multidrug-resistant mycobacterial strains is a significant crisis that has led to higher treatment failure rates and more toxic and expensive medications for tuberculosis (TB). The urgent need to develop novel therapeutics has galvanized research interest towards developing alternative antimicrobials such as silver nanoparticles (AgNPs). The current study focused on the anti-mycobacterial activity of green-synthesized AgNPs and its polyethylene glycol encapsulated derivative (PEG-AgNPs) with improved stability using the leaves extract of . Different characterization methods were used to analyze them. DLS analysis revealed a lower polydispersity index of PEG-AgNPs, suggesting a more uniform size distribution than that of AgNPs. The HR-TEM results revealed that the AgNPs and PEG-AgNPs have predominantly spherical shapes in the size range of 9-35 nm and 15-60 nm, respectively, while positive values of Zeta potential indicate their stability. FTIR-ATR analysis confirmed the presence of functional groups responsible for reducing and capping the bio-reduced AgNPs, whereas the XRD data established its crystalline nature. Impressively, the PEG-AgNPs exhibited maximum inhibitory activity against different Tubercular and Non-Tuberculous species , and , relative to those of AgNPs and Linezolid. The flow cytometry assay showed that the anti-mycobacterial action was mediated by an increase in cell wall permeability. Notably, the results of AFM confirm their ability to inhibit mycobacterial biofilm significantly. We demonstrated the nontoxic nature of these AgNPs, explicated by the absence of hemolytic activity against human RBCs. Overall, the results suggest that PEG-AgNPs could offer a novel therapeutic approach with potential anti-mycobacterial activity and can overcome the limitations of existing TB therapies.
PubMed: 38799742
DOI: 10.1016/j.heliyon.2024.e31116 -
IScience May 2024Type I interferon (IFN) production is crucial in tuberculosis pathogenesis, yet the bacterial factors initiating this process are incompletely understood. CpsA, protein...
Type I interferon (IFN) production is crucial in tuberculosis pathogenesis, yet the bacterial factors initiating this process are incompletely understood. CpsA, protein of , plays a key role in maintaining bacterial virulence and inhibiting host cell LC3-associated phagocytosis. By utilizing CpsA full deletion mutant studies, we re-verified its essential role in infection-induced pathology and revealed its new role in type I IFN expression. CpsA deficiency hindered IFN production in infected macrophages as well as zebrafish and mice . This effect was linked to the cGAS-TBK1-IRF3 pathway, as evidenced by decreased TBK1 and IRF3 phosphorylation in CpsA-deficient bacterial strain-infected macrophages. Moreover, we further show that CpsA deficiency cause decreased cytosolic DNA levels, correlating with impaired phagosomal membrane rupture. Our findings reveal a new function of mycobacterial CpsA in type I IFN production and offer insight into the molecular mechanisms underlying mycobacterial infection pathology.
PubMed: 38766355
DOI: 10.1016/j.isci.2024.109807 -
Life Science Alliance Jul 2024Developing effective tuberculosis drugs is hindered by mycobacteria's intrinsic antibiotic resistance because of their impermeable cell envelope. Using benzothiazole...
Developing effective tuberculosis drugs is hindered by mycobacteria's intrinsic antibiotic resistance because of their impermeable cell envelope. Using benzothiazole compounds, we aimed to increase mycobacterial cell envelope permeability and weaken the defenses of , serving as a model for Initial hit, BT-08, significantly boosted ethidium bromide uptake, indicating enhanced membrane permeability. It also demonstrated efficacy in the -zebrafish embryo infection model and -infected macrophages. Notably, BT-08 synergized with established antibiotics, including vancomycin and rifampicin. Subsequent medicinal chemistry optimization led to BT-37, a non-toxic and more potent derivative, also enhancing ethidium bromide uptake and maintaining synergy with rifampicin in infected zebrafish embryos. Mutants of resistant to BT-37 revealed that MMAR_0407 (Rv0164) is the molecular target and that this target plays a role in the observed synergy and permeability. This study introduces novel compounds targeting a new mycobacterial vulnerability and highlights their cooperative and synergistic interactions with existing antibiotics.
Topics: Animals; Zebrafish; Benzothiazoles; Drug Synergism; Mycobacterium marinum; Antitubercular Agents; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Humans; Anti-Bacterial Agents; Cell Membrane Permeability; Macrophages; Mycobacterium Infections, Nontuberculous; Cell Membrane; Rifampin
PubMed: 38744470
DOI: 10.26508/lsa.202302509 -
Journal of Infection in Developing... Apr 2024Mycobacterium marinum infection rarely occurs and has atypical symptoms. It is challenging to distinguish disseminated M. marinum infection from multifocal dermatosis...
INTRODUCTION
Mycobacterium marinum infection rarely occurs and has atypical symptoms. It is challenging to distinguish disseminated M. marinum infection from multifocal dermatosis caused by other factors clinically.
CASE PRESENTATION
Herein, we reported a 68-year-old male patient with Human Immunodeficiency Virus (HIV) who presented redness and swelling in his left hand after being stabbed by marine fish for over 2 months. Mycobacterium tuberculosis infection was considered according to biochemical and pathological examinations, while empirical anti-infection treatment was ineffective.
RESULTS
The metagenomic next-generation sequencing (mNGS) detected a large amount of M. marinum sequences, and the patient was finally diagnosed with M. marinum infection. After one month of combination therapy with ethambutol, rifabutin, moxifloxacin, and linezolid, the swelling disappeared significantly. In this case, the successful application of mNGS in diagnosing and treating M. marinum infection has improved the understanding of the microbe both in the laboratory and clinically, especially in patients with HIV.
CONCLUSIONS
For diseases with atypical symptoms or difficulty in determining the pathogens, mNGS is suggested in clinical procedures for rapid and accurate diagnosis and treatment.
Topics: Humans; Male; Mycobacterium Infections, Nontuberculous; Aged; Mycobacterium marinum; HIV Infections; High-Throughput Nucleotide Sequencing; Metagenomics; Ethambutol; Anti-Bacterial Agents
PubMed: 38728638
DOI: 10.3855/jidc.18114 -
Vitamin B uptake across the mycobacterial outer membrane is influenced by membrane permeability in .Microbiology Spectrum Jun 2024Vitamin B (B) serves as a critical cofactor within mycobacterial metabolism. While some pathogenic strains can synthesize B , others rely on host-acquired B. In this...
Vitamin B (B) serves as a critical cofactor within mycobacterial metabolism. While some pathogenic strains can synthesize B , others rely on host-acquired B. In this investigation, we studied the transport of vitamin B in using B-auxotrophic and B-sensitive strains by deleting or , respectively. These two enzymes rely on B in different ways to function as methionine synthases. We used these strains to select mutants affecting B scavenging and confirmed their phenotypes during growth experiments . Our analysis of B uptake mechanisms revealed that membrane lipids and cell wall integrity play an essential role in cell envelope transport. Furthermore, we identified a potential transcription regulator that responds to B. Our study demonstrates that can take up exogenous B and that altering mycobacterial membrane integrity affects B uptake. Finally, during zebrafish infection using B-auxotrophic and B-sensitive strains, we found that B is available for virulent mycobacteria .IMPORTANCEOur study investigates how mycobacteria acquire essential vitamin B. These microbes, including those causing tuberculosis, face challenges in nutrient uptake due to their strong outer layer. We focused on , similar to TB bacteria, to uncover its vitamin B absorption. We used modified strains unable to produce their own B and discovered that can indeed absorb it from the environment, even during infections. Changes in the outer layer composition affect this process, and genes related to membrane integrity play key roles. These findings illuminate the interaction between mycobacteria and their environment, offering insights into combatting diseases like tuberculosis through innovative strategies. Our concise research underscores the pivotal role of vitamin B in microbial survival and its potential applications in disease control.
Topics: Mycobacterium marinum; Vitamin B 12; Animals; Zebrafish; Bacterial Outer Membrane; Bacterial Proteins; Cell Membrane Permeability; Biological Transport; Cell Membrane; Mycobacterium Infections, Nontuberculous
PubMed: 38722177
DOI: 10.1128/spectrum.03168-23 -
Microbiology Spectrum Jun 2024Four species of non-tuberculous mycobacteria (NTM) rated as biosafety level 1 or 2 (BSL-1/BSL-2) organisms and showing higher genomic similarity with () than previous...
Four species of non-tuberculous mycobacteria (NTM) rated as biosafety level 1 or 2 (BSL-1/BSL-2) organisms and showing higher genomic similarity with () than previous comparator species and were subjected to genomic and phenotypic characterization. These species named , , and might represent "missing links" between low-virulent mycobacterial opportunists and the highly virulent obligate pathogen . We confirmed that is the closest NTM species to currently known and found that it has an optimal growth temperature of 32°C-35°C and not 37°C. showed resistance to rifampicin, isoniazid, and ethambutol, whereas and showed resistance to isoniazid and ethambutol. was sensitive to all three first-line TB drugs, and all four species were sensitive to bedaquiline, a third-generation anti-TB drug. Our results suggest these four NTM may be useful models for the identification and study of new anti-TB molecules, facilitated by their culture under non-BSL-3 conditions as compared to was the most virulent of the four species in cellular and mouse infection models. also multiplied in THP-1 cells at 35°C but was growth impaired at 37°C. Genomic comparisons showed that the locus, essential for the secretion of ESX-1 proteins in , was present only in , which was able to secrete ESAT-6 and CFP-10, whereas secretion of these antigens varied in the other species, making the four species interesting examples for studying ESX-1 secretion mechanisms.IMPORTANCEIn this work, we investigated recently identified opportunistic mycobacterial pathogens that are genomically more closely related to () than previously used comparator species and . We confirmed that is the currently closest known species to the tubercle bacilli, represented by and strains. Surprisingly, the reference strain of (DSM 45176), which was purchased as a biosafety level 1 (BSL-1)-rated organism, was the most virulent of the four species in the tested cellular and mouse infection models, suggesting that a BSL-2 rating might be more appropriate for this strain than the current BSL-1 rating. Our work establishes the four NTM species as interesting study models to obtain new insights into the evolutionary mechanisms and phenotypic particularities of mycobacterial pathogens that likely have also impacted the evolution of the key pathogen .
Topics: Mycobacterium tuberculosis; Antitubercular Agents; Nontuberculous Mycobacteria; Humans; Genome, Bacterial; Genomics; Phenotype; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous; Phylogeny; Animals; Tuberculosis; Drug Resistance, Bacterial; Mice
PubMed: 38700329
DOI: 10.1128/spectrum.04126-23 -
MSphere May 2024The mycobacterial cell envelope is a major virulence determinant in pathogenic mycobacteria. Specific outer lipids play roles in pathogenesis, modulating the immune...
The mycobacterial cell envelope is a major virulence determinant in pathogenic mycobacteria. Specific outer lipids play roles in pathogenesis, modulating the immune system and promoting the secretion of virulence factors. ESX-1 (ESAT-6 system-1) is a conserved protein secretion system required for mycobacterial pathogenesis. Previous studies revealed that mycobacterial strains lacking the outer lipid PDIM have impaired ESX-1 function during laboratory growth and infection. The mechanisms underlying changes in ESX-1 function are unknown. We used a proteo-genetic approach to measure phthiocerol dimycocerosate (PDIM)- and phenolic glycolipid (PGL)-dependent protein secretion in a non-tubercular mycobacterial pathogen that causes tuberculosis-like disease in ectothermic animals. Importantly, is a well-established model for mycobacterial pathogenesis. Our findings showed that strains without PDIM and PGL showed specific, significant reductions in protein secretion compared to the WT and complemented strains. We recently established a hierarchy for the secretion of ESX-1 substrates in four (I-IV) groups. Loss of PDIM differentially impacted secretion of Group III and IV ESX-1 substrates, which are likely the effectors of pathogenesis. Our data suggest that the altered secretion of specific ESX-1 substrates is responsible for the observed ESX-1-related effects in PDIM-deficient strains.IMPORTANCE the cause of human tuberculosis, killed an estimated 1.3 million people in 2022. Non-tubercular mycobacterial species cause acute and chronic human infections. Understanding how these bacteria cause disease is critical. Lipids in the cell envelope are essential for mycobacteria to interact with the host and promote disease. Strains lacking outer lipids are attenuated for infection, but the reasons are unclear. Our research aims to identify a mechanism for attenuation of mycobacterial strains without the PDIM and PGL outer lipids in . These findings will enhance our understanding of the importance of lipids in pathogenesis and how these lipids contribute to other established virulence mechanisms.
Topics: Mycobacterium marinum; Bacterial Proteins; Virulence Factors; Glycolipids; Virulence; Lipids; Antigens, Bacterial
PubMed: 38661343
DOI: 10.1128/msphere.00005-24 -
Open Forum Infectious Diseases Apr 2024The objective of our study is to describe the clinical presentation, management, and outcome of a large cohort with nontuberculous mycobacteria (NTM) hand infection.
BACKGROUND
The objective of our study is to describe the clinical presentation, management, and outcome of a large cohort with nontuberculous mycobacteria (NTM) hand infection.
METHODS
We reviewed the medical records of all adults (≥18 years) managed at the Mayo Clinic (Rochester, MN) for NTM hand infection between 1998 and 2018.
RESULTS
Our cohort included 81 patients. The median age was 61.3 (interquartile range 51.7, 69.6) years; 39.5% were immunocompromised, and 67.9% reported a triggering exposure preceding infection. Infection was deep in 64.2% and disseminated in 3.7%. Up to 16.0% received intralesional steroids because of misdiagnosis with an inflammatory process. Immunocompromised patients had deeper infection, and fewer reports of a triggering exposure. , complex, and complex were the most common species. The median antibiotic duration was 6.1 (interquartile range 4.6, 9.9) months. Deep infection and infection with species other than were associated with using a greater number of antibiotics for combination therapy and an extended duration of treatment. Immunosuppression was also associated with longer courses of antibiotic therapy. Surgery was performed in 86.5% and 32.4% required multiple procedures. Ten patients, mostly with superficial infections, were treated with antibiotics alone. The 5-year cumulative rate of treatment failure was 30.3% (95% confidence interval, 20.9-44.0). Immunosuppression and intralesional steroid use were risk factors for failure.
CONCLUSIONS
Treatment of NTM hand infection usually requires surgery and antibiotics, but antibiotics alone may occasionally be attempted in select cases. Immunosuppression and intralesional steroids are risk factors for treatment failure.
PubMed: 38651140
DOI: 10.1093/ofid/ofae152