469 results on '"Mycolactone"'
Search Results
2. Current Progress and Prospects for a Buruli Ulcer Vaccine
- Author
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Boakye-Appiah, Justice, Hall, Belinda, Reljic, Rajko, Simmonds, Rachel E., and Christodoulides, Myron, editor
- Published
- 2023
- Full Text
- View/download PDF
3. Alternative boronic acids in the detection of Mycolactone A/B using the thin layer chromatography (f-TLC) method for diagnosis of Buruli ulcer
- Author
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Gideon A. Akolgo, Benjamin M. Partridge, Timothy D. Craggs, and Richard K. Amewu
- Subjects
Buruli ulcer ,Arylboronic acid ,Mycobacterium ulcerans ,Mycolactone ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Mycobacterium ulcerans is the causative agent of Buruli ulcer. The pathology of M. ulcerans disease has been attributed to the secretion of a potent macrolide cytotoxin known as mycolactone which plays an important role in the virulence of the disease. Mycolactone is a biomarker for the diagnosis of BU that can be detected using the fluorescent-thin layer chromatography (f-TLC) technique. The technique relies on the chemical derivatization of mycolactone A/B with 2-naphthylboronic acid (BA) which acts as a fluorogenic chemosensor. However, background interferences due to co-extracted human tissue lipids, especially with clinical samples coupled with the subjectivity of the method call for an investigation to find an alternative to BA. Methods Twenty-six commercially available arylboronic acids were initially screened as alternatives to BA using the f-TLC experiment. UV–vis measurements were also conducted to determine the absorption maximum spectra of mycolactone A/B and myco-boronic acid adducts followed by an investigation of the fluorescence-enhancing ability of the boronate ester formation between mycolactone A/B and our three most promising boronic acids (BA15, BA18, and BA21). LC–MS technique was employed to confirm the adduct formation between mycolactone and boronic acids. Furthermore, a comparative study was conducted between BA18 and BA using 6 Polymerase Chain Reaction (PCR) confirmed BU patient samples. Results Three of the boronic acids (BA15, BA18, and BA21) produced fluorescent band intensities superior to BA. Complexation studies conducted on thin layer chromatography (TLC) using 0.1 M solution of the three boronic acids and various volumes of 10 ng/µL of synthetic mycolactone ranging from 1 µL – 9 µL corresponding to 10 ng – 90 ng gave similar results with myco-BA18 adduct emerging with the most visibly intense fluorescence bands. UV–vis absorption maxima (λmax) for the free mycolactone A/B was observed at 362 nm, and the values for the adducts myco-BA15, myco-BA18, and myco-BA21 were at 272 nm, 270 nm, and 286 nm respectively. The comparable experimental λmax of 362 nm for mycolactone A/B to the calculated Woodward-Fieser value of 367 nm for the fatty acid side chain of mycolactone A/B demonstrate that even though 2 cyclic boronates were formed, only the boronate of the southern side chain with the chromophore was excited by irradiation at 365 nm. Fluorescence experiments have demonstrated that coupling BA18 to mycolactone A/B along the 1,3-diols remarkably enhanced the fluorescence intensity at 537 nm. High-Resolution Mass Spectrometer (HR-MS) was used to confirm the formation of the myco-BA15 adduct. Finally, f-TLC analysis of patient samples with BA18 gave improved BA18-adduct intensities compared to the original BA-adduct. Conclusion Twenty-six commercially available boronic acids were investigated as alternatives to BA, used in the f-TLC analysis for the diagnosis of BU. Three (3) of them BA15, BA18, and BA21 gave superior fluorescence band intensity profiles. They gave profiles that were easier to interpret after the myco-boronic acid adduct formation and in experiments with clinical samples from patients with BA18 the best. BA18, therefore, has been identified as a potential alternative to BA and could provide a solution to the challenge of background interference of co-extracted human tissue lipids from clinical samples currently associated with the use of BA.
- Published
- 2023
- Full Text
- View/download PDF
4. Mycolactone A vs. B: Multiscale Simulations Reveal the Roles of Localization and Association in Isomer-Specific Toxicity.
- Author
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Nguyen, John D. M., da Hora, Gabriel C. A., and Swanson, Jessica M. J.
- Subjects
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BURULI ulcer , *MEMBRANE proteins , *EXOTOXIN , *PEPTIDES , *MOLECULAR dynamics , *NEGLECTED diseases - Abstract
Mycolactone is an exotoxin produced by Mycobacterium ulcerans that causes the neglected tropical skin disease Buruli ulcer. This toxin inhibits the Sec61 translocon in the endoplasmic reticulum (ER), preventing the host cell from producing several secretory and transmembrane proteins, resulting in cytotoxic and immunomodulatory effects. Interestingly, only one of the two dominant isoforms of mycolactone is cytotoxic. Here, we investigate the origin of this specificity by performing extensive molecular dynamics (MD) simulations with enhanced free energy sampling to query the association trends of the two isoforms with both the Sec61 translocon, using two distinct cryo-electron microscopy (cryo-EM) models as references, and the ER membrane, which serves as a toxin reservoir prior to association. Our results suggest that mycolactone B (the cytotoxic isoform) has a stronger association with the ER membrane than mycolactone A due to more favorable interactions with membrane lipids and water molecules. This could increase the reservoir of toxin proximal to the Sec61 translocon. In one model of Sec61 inhibited by mycolactone, we find that isomer B interacts more closely with residues thought to play a key role in signal peptide recognition and, thus, are essential for subsequent protein translocation. In the other model, we find that isomer B interacts more closely with the lumenal and lateral gates of the translocon, the dynamics of which are essential for protein translocation. These interactions induce a more closed conformation, which has been suggested to block signal peptide insertion and subsequent protein translocation. Collectively, these findings suggest that isomer B's unique cytotoxicity is a consequence of both increased localization to the ER membrane and channel-locking association with the Sec61 translocon, facets that could be targeted in the development of Buruli Ulcer diagnostics and Sec61-targeted therapeutics. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Alternative boronic acids in the detection of Mycolactone A/B using the thin layer chromatography (f-TLC) method for diagnosis of Buruli ulcer.
- Author
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Akolgo, Gideon A., Partridge, Benjamin M., D. Craggs, Timothy, and Amewu, Richard K.
- Subjects
- *
BURULI ulcer , *THIN layer chromatography , *BORONIC acids , *DIAGNOSIS methods , *BORONIC esters , *POLYMERASE chain reaction , *PHOSPHONATES - Abstract
Background: Mycobacterium ulcerans is the causative agent of Buruli ulcer. The pathology of M. ulcerans disease has been attributed to the secretion of a potent macrolide cytotoxin known as mycolactone which plays an important role in the virulence of the disease. Mycolactone is a biomarker for the diagnosis of BU that can be detected using the fluorescent-thin layer chromatography (f-TLC) technique. The technique relies on the chemical derivatization of mycolactone A/B with 2-naphthylboronic acid (BA) which acts as a fluorogenic chemosensor. However, background interferences due to co-extracted human tissue lipids, especially with clinical samples coupled with the subjectivity of the method call for an investigation to find an alternative to BA. Methods: Twenty-six commercially available arylboronic acids were initially screened as alternatives to BA using the f-TLC experiment. UV–vis measurements were also conducted to determine the absorption maximum spectra of mycolactone A/B and myco-boronic acid adducts followed by an investigation of the fluorescence-enhancing ability of the boronate ester formation between mycolactone A/B and our three most promising boronic acids (BA15, BA18, and BA21). LC–MS technique was employed to confirm the adduct formation between mycolactone and boronic acids. Furthermore, a comparative study was conducted between BA18 and BA using 6 Polymerase Chain Reaction (PCR) confirmed BU patient samples. Results: Three of the boronic acids (BA15, BA18, and BA21) produced fluorescent band intensities superior to BA. Complexation studies conducted on thin layer chromatography (TLC) using 0.1 M solution of the three boronic acids and various volumes of 10 ng/µL of synthetic mycolactone ranging from 1 µL – 9 µL corresponding to 10 ng – 90 ng gave similar results with myco-BA18 adduct emerging with the most visibly intense fluorescence bands. UV–vis absorption maxima (λmax) for the free mycolactone A/B was observed at 362 nm, and the values for the adducts myco-BA15, myco-BA18, and myco-BA21 were at 272 nm, 270 nm, and 286 nm respectively. The comparable experimental λmax of 362 nm for mycolactone A/B to the calculated Woodward-Fieser value of 367 nm for the fatty acid side chain of mycolactone A/B demonstrate that even though 2 cyclic boronates were formed, only the boronate of the southern side chain with the chromophore was excited by irradiation at 365 nm. Fluorescence experiments have demonstrated that coupling BA18 to mycolactone A/B along the 1,3-diols remarkably enhanced the fluorescence intensity at 537 nm. High-Resolution Mass Spectrometer (HR-MS) was used to confirm the formation of the myco-BA15 adduct. Finally, f-TLC analysis of patient samples with BA18 gave improved BA18-adduct intensities compared to the original BA-adduct. Conclusion: Twenty-six commercially available boronic acids were investigated as alternatives to BA, used in the f-TLC analysis for the diagnosis of BU. Three (3) of them BA15, BA18, and BA21 gave superior fluorescence band intensity profiles. They gave profiles that were easier to interpret after the myco-boronic acid adduct formation and in experiments with clinical samples from patients with BA18 the best. BA18, therefore, has been identified as a potential alternative to BA and could provide a solution to the challenge of background interference of co-extracted human tissue lipids from clinical samples currently associated with the use of BA. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
6. From Bacterial Toxin to Therapeutic Agent: The Unexpected Fate of Mycolactone.
- Author
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Ricci, Daniela and Demangel, Caroline
- Subjects
- *
BURULI ulcer , *NEGLECTED diseases , *VIRUS diseases , *VIRAL transmission , *BACTERIAL toxins , *CHRONIC diseases , *TOXINS - Abstract
"Recognizing a surprising fact is the first step towards discovery." This famous quote from Louis Pasteur is particularly appropriate to describe what led us to study mycolactone, a lipid toxin produced by the human pathogen Mycobacterium ulcerans. M. ulcerans is the causative agent of Buruli ulcer, a neglected tropical disease manifesting as chronic, necrotic skin lesions with a "surprising" lack of inflammation and pain. Decades after its first description, mycolactone has become much more than a mycobacterial toxin. This uniquely potent inhibitor of the mammalian translocon (Sec61) helped reveal the central importance of Sec61 activity for immune cell functions, the spread of viral particles and, unexpectedly, the viability of certain cancer cells. We report in this review the main discoveries that marked our research into mycolactone, and the medical perspectives they opened up. The story of mycolactone is not over and the applications of Sec61 inhibition may go well beyond immunomodulation, viral infections, and oncology. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
7. Mycolactone: A Broad Spectrum Multitarget Antiviral Active in the Picomolar Range for COVID-19 Prevention and Cure.
- Author
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Asiedu, Seth Osei, Gupta, Yash, Nicolaescu, Vlad, Gula, Haley, Caulfield, Thomas R., Durvasula, Ravi, Kempaiah, Prakasha, Kwofie, Samuel K., and Wilson, Michael D.
- Subjects
- *
SARS-CoV-2 Omicron variant , *COVID-19 , *CHIMERIC proteins , *BLOOD platelets , *COATED vesicles , *CLATHRIN - Abstract
We have previously shown computationally that Mycolactone (MLN), a toxin produced by Mycobacterium ulcerans, strongly binds to Munc18b and other proteins, presumably blocking degranulation and exocytosis of blood platelets and mast cells. We investigated the effect of MLN on endocytosis using similar approaches, and it bound strongly to the N-terminal of the clathrin protein and a novel SARS-CoV-2 fusion protein. Experimentally, we found 100% inhibition up to 60 nM and 84% average inhibition at 30 nM in SARS-CoV-2 live viral assays. MLN was also 10× more potent than remdesivir and molnupiravir. MLN's toxicity against human alveolar cell line A549, immortalized human fetal renal cell line HEK293, and human hepatoma cell line Huh7.1 were 17.12%, 40.30%, and 36.25%, respectively. The cytotoxicity IC50 breakpoint ratio versus anti-SARS-CoV-2 activity was more than 65-fold. The IC50 values against the alpha, delta, and Omicron variants were all below 0.020 µM, and 134.6 nM of MLN had 100% inhibition in an entry and spread assays. MLN is eclectic in its actions through its binding to Sec61, AT2R, and the novel fusion protein, making it a good drug candidate for treating and preventing COVID-19 and other similarly transmitted enveloped viruses and pathogens. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
8. BuDb: A Curated Drug Discovery Database for Buruli Ulcer.
- Author
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kwofie, Samuel K., Anyimadu, Daniel Tweneboah, Aryee, Solomon, Asare, Blessing, Kokroko, Natalie, Owusu, Jeffrey A., Afutu, Baron, Agyapong, Odame, Mosi, Lydia, Kyei-Baffour, Edwin, Enninful, Kweku S., Agoni, Clement, and Wilson, Michael D.
- Subjects
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DRUG discovery , *BURULI ulcer , *DATABASES , *PLANT genomes , *DRUG target - Abstract
Buruli ulcer (BU), a severe skin disease is caused by Mycobacterium ulcerans. There are concerns of therapeutic inefficacy of existing drugs coupled with chemoresistance. Databases have been shown to augment data mining and integrative systems pharmacology approaches towards the search for novel therapeutic moieties. So far, there is no known integrated database solely dedicated to BU drug discovery. In this work, Buruli ulcer database (BuDb) is a "one-stop-shop" knowledgebase for supporting BU drug discovery. It contains both manually verified literature and database-curated data on BU. The BuDb provides comprehensive information on the various drug targets, tested compounds, existing drugs, ethnopharmacological plants and information on the genome of M. ulcerans. It also contains cross-referenced links to databases including PubMed, PubChem, DrugBank, NCBI, Gene Ontology (GO), UniProt, Prota4u, String database, KEGG Pathway and KEGG genome database. The BuDb has been implemented with accessibility features such as keyword and specific searches as well as browsing. BuDb is the first useful online repository of its kind integrated with enriched datasets that can aid in the discovery of new biotherapeutic entities for BU. BuDb can be freely accessed at http://197.255.126.13:3000/. BuDb is the first online database that support the discovery of new biotherapeutic entities for Buruli ulcer. BuDb provides comprehensive information on the various drug targets, tested compounds, existing drugs and ethnopharmacological plants. BuDb is cross-referenced to functional genomic data, pathways and gene ontologies relating to Mycobacterium ulcerans. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. Mycolactone A vs. B: Multiscale Simulations Reveal the Roles of Localization and Association in Isomer-Specific Toxicity
- Author
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John D. M. Nguyen, Gabriel C. A. da Hora, and Jessica M. J. Swanson
- Subjects
mycolactone ,Buruli ulcer ,ER membrane ,Sec61 translocon ,molecular dynamics ,membrane permeation ,Medicine - Abstract
Mycolactone is an exotoxin produced by Mycobacterium ulcerans that causes the neglected tropical skin disease Buruli ulcer. This toxin inhibits the Sec61 translocon in the endoplasmic reticulum (ER), preventing the host cell from producing several secretory and transmembrane proteins, resulting in cytotoxic and immunomodulatory effects. Interestingly, only one of the two dominant isoforms of mycolactone is cytotoxic. Here, we investigate the origin of this specificity by performing extensive molecular dynamics (MD) simulations with enhanced free energy sampling to query the association trends of the two isoforms with both the Sec61 translocon, using two distinct cryo-electron microscopy (cryo-EM) models as references, and the ER membrane, which serves as a toxin reservoir prior to association. Our results suggest that mycolactone B (the cytotoxic isoform) has a stronger association with the ER membrane than mycolactone A due to more favorable interactions with membrane lipids and water molecules. This could increase the reservoir of toxin proximal to the Sec61 translocon. In one model of Sec61 inhibited by mycolactone, we find that isomer B interacts more closely with residues thought to play a key role in signal peptide recognition and, thus, are essential for subsequent protein translocation. In the other model, we find that isomer B interacts more closely with the lumenal and lateral gates of the translocon, the dynamics of which are essential for protein translocation. These interactions induce a more closed conformation, which has been suggested to block signal peptide insertion and subsequent protein translocation. Collectively, these findings suggest that isomer B’s unique cytotoxicity is a consequence of both increased localization to the ER membrane and channel-locking association with the Sec61 translocon, facets that could be targeted in the development of Buruli Ulcer diagnostics and Sec61-targeted therapeutics.
- Published
- 2023
- Full Text
- View/download PDF
10. Transcriptional adaptation of Mycobacterium ulcerans in an original mouse model: New insights into the regulation of mycolactone
- Author
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Marie Robbe-Saule, Mélanie Foulon, Isabelle Poncin, Lucille Esnault, Hugo Varet, Rachel Legendre, Alban Besnard, Anna E. Grzegorzewicz, Mary Jackson, Stéphane Canaan, Laurent Marsollier, and Estelle Marion
- Subjects
mycobacterium ulcerans ,host-bacterium interaction ,mycolactone ,rna-sequencing ,metabolism ,Infectious and parasitic diseases ,RC109-216 - Abstract
Mycobacterium ulcerans is the causal agent of Buruli ulcer, a chronic infectious disease and the third most common mycobacterial disease worldwide. Without early treatment, M. ulcerans provokes massive skin ulcers, caused by the mycolactone toxin, its main virulence factor. However, spontaneous healing may occur in Buruli ulcer patients several months or years after the disease onset. We have shown, in an original mouse model, that bacterial load remains high and viable in spontaneously healed tissues, with a switch of M. ulcerans to low levels of mycolactone production, adapting its strategy to survive in such a hostile environment. This original model offers the possibility to investigate the regulation of mycolactone production, by using an RNA-seq strategy to study bacterial adaptation during mouse infection. Pathway analysis and characterization of the tissue environment showed that the bacillus adapted to its new environment by modifying its metabolic activity and switching nutrient sources. Thus, M. ulcerans ensures its survival in healing tissues by reducing its secondary metabolism, leading to an inhibition of mycolactone synthesis. These findings shed new light on mycolactone regulation and pave the way for new therapeutic strategies.
- Published
- 2021
- Full Text
- View/download PDF
11. Buruli ulcer: An epidemiological update from Japan.
- Author
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Fukaura R, Ato M, Murase C, Miyamoto Y, Sugawara-Mikami M, Takahashi T, Hoshino Y, Fujimoto N, Akiyama M, Ishii N, and Yotsu R
- Abstract
Japan is one of the rare non-tropical countries with documented cases of Buruli ulcer (BU). Mycobacterium ulcerans subsp. shinshuense has been identified as the causative agent. The first report of BU in Japan dates back to 1982, with sporadic reports thereafter. Recently, the number of cases has been on the increase, and 50 cases (57.7%) are from the past decade alone, out of a total of 87 cases reported to date. Japan's well-developed healthcare facilities play a crucial role in enabling detailed investigations and providing appropriate treatment for patients, contributing to a favorable prognosis. However, the rarity of the disease results in lack of awareness among healthcare professionals, leading to frequent delays in diagnosis. This article aims to offer an updated overview of BU cases in Japan and to raise awareness of BU among dermatologists and other healthcare professionals in a non-endemic setting., (© 2024 The Author(s). The Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Dermatological Association.)
- Published
- 2024
- Full Text
- View/download PDF
12. From Bacterial Toxin to Therapeutic Agent: The Unexpected Fate of Mycolactone
- Author
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Daniela Ricci and Caroline Demangel
- Subjects
mycolactone ,Mycobacterium ulcerans ,Sec61 ,immunomodulation ,viral infection ,cancer ,Medicine - Abstract
“Recognizing a surprising fact is the first step towards discovery.” This famous quote from Louis Pasteur is particularly appropriate to describe what led us to study mycolactone, a lipid toxin produced by the human pathogen Mycobacterium ulcerans. M. ulcerans is the causative agent of Buruli ulcer, a neglected tropical disease manifesting as chronic, necrotic skin lesions with a “surprising” lack of inflammation and pain. Decades after its first description, mycolactone has become much more than a mycobacterial toxin. This uniquely potent inhibitor of the mammalian translocon (Sec61) helped reveal the central importance of Sec61 activity for immune cell functions, the spread of viral particles and, unexpectedly, the viability of certain cancer cells. We report in this review the main discoveries that marked our research into mycolactone, and the medical perspectives they opened up. The story of mycolactone is not over and the applications of Sec61 inhibition may go well beyond immunomodulation, viral infections, and oncology.
- Published
- 2023
- Full Text
- View/download PDF
13. Density Functional Theory-Based Studies Predict Carbon Nanotubes as Effective Mycolactone Inhibitors.
- Author
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Suleiman, Nafiu, Yaya, Abu, Wilson, Michael D., Aryee, Solomon, and Kwofie, Samuel K.
- Subjects
- *
CARBON nanotubes , *BORON nitride , *DENSITY functional theory , *TOXINS , *NANOTUBES , *CHEMICAL properties - Abstract
Fullerenes, boron nitride nanotubes (BNNTs), and carbon nanotubes (CNTs) have all been extensively explored for biomedical purposes. This work describes the use of BNNTs and CNTs as mycolactone inhibitors. Density functional theory (DFT) has been used to investigate the chemical properties and interaction mechanisms of mycolactone with armchair BNNTs (5,5) and armchair CNTs (5,5). By examining the optimized structure and interaction energy, the intermolecular interactions between mycolactone and nanotubes were investigated. The findings indicate that mycolactone can be physically adsorbed on armchair CNTs in a stable condition, implying that armchair CNTs can be potential inhibitors of mycolactone. According to DOS plots and HOMO–LUMO orbital studies, the electronic characteristics of pure CNTs are not modified following mycolactone adsorption on the nanotubes. Because of mycolactone's large π-π interactions with CNTs, the estimated interaction energies indicate that mycolactone adsorption on CNTs is preferable to that on BNNTs. CNTs can be explored as potentially excellent inhibitors of mycolactone toxins in biological systems. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
14. Co-infection of HIV in patients with Buruli ulcer disease in Central Ghana
- Author
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Yaw Ampem Amoako, Aloysius Dzigbordi Loglo, Michael Frimpong, Bernadette Agbavor, Mohammed Kabiru Abass, George Amofa, Elizabeth Ofori, Edwin Ampadu, Kingsley Asiedu, Ymkje Stienstra, Mark Wansbrough-Jones, Tjip van der Werf, and Richard Odame Phillips
- Subjects
Buruli ulcer ,Human immunodeficiency syndrome ,Coinfection ,Mycolactone ,Interferon-gamma ,Antiretroviral therapy ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Previous studies have reported that presence and severity of Buruli ulcer (BU) may reflect the underlying immunosuppression in HIV infected individuals by causing increased incidence of multiple, larger and ulcerated lesions. We report cases of BU-HIV coinfection and the accompanying programmatic challenges encountered in central Ghana. Methods Patients with PCR confirmed BU in central Ghana who were HIV positive were identified and their BU01 forms were retrieved and reviewed in further detail. A combined 16S rRNA reverse transcriptase / IS2404 qPCR assay was used to assess the Mycobacterium ulcerans load. The characteristics of coinfected patients (BU+HIV+) were compared with a group of matched controls. Results The prevalence of HIV in this BU cohort was 2.4% (compared to national HIV prevalence of 1.7%). Eight of 9 BU+HIV+ patients had a single lesion and ulcers were the most common lesion type. The lesions presented were predominantly category II (5/9) followed by category I lesions. The median (IQR) time to healing was 14 (8–28) weeks in the BU+HIV+ compared to 28 (12–33) weeks in the control BU+HIV− group (p = 0.360). Only one BU+HIV+ developed a paradoxical reaction at week 16 but the lesion healed completely at week 20. The median bacterial load (16SrRNA) of BU+HIV+ patients was 750 copies /ml (95% CI 0–398,000) versus 500 copies/ml (95% CI 0–126,855,500) in BU+HIV− group. Similarly, the median count using the IS2404 assay was 500 copies/ml (95% CI 0–500) for BU+HIV+ patients versus 500 copies/ml (95% CI 500–31,000) for BU+HIV− patients. BU+HIV− patients mounted a significantly higher interferon-γ response compared to the BU+HIV+ co-infected patients with respective median (range) responses of [1687(81.11–4399) pg/ml] versus [137.5(4.436–1406) pg/ml, p = 0.03]. There were challenges with the integration of HIV and BU care in this cohort. Conclusion The prevalence of HIV in the BU+ infected population was not significantly increased when compared to the prevalence of HIV in the general population. There was no clear relationship between BU lesion severity and HIV viral load or CD4 counts. Efforts should be made to encourage the integration of care of patients with BU-HIV coinfection.
- Published
- 2021
- Full Text
- View/download PDF
15. Mycolactone: A Broad Spectrum Multitarget Antiviral Active in the Picomolar Range for COVID-19 Prevention and Cure
- Author
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Seth Osei Asiedu, Yash Gupta, Vlad Nicolaescu, Haley Gula, Thomas R. Caulfield, Ravi Durvasula, Prakasha Kempaiah, Samuel K. Kwofie, and Michael D. Wilson
- Subjects
COVID-19 ,Mycobacterium ulcerans ,mycolactone ,SARS-CoV-2 ,viral cell entry and exit ,treatment ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
We have previously shown computationally that Mycolactone (MLN), a toxin produced by Mycobacterium ulcerans, strongly binds to Munc18b and other proteins, presumably blocking degranulation and exocytosis of blood platelets and mast cells. We investigated the effect of MLN on endocytosis using similar approaches, and it bound strongly to the N-terminal of the clathrin protein and a novel SARS-CoV-2 fusion protein. Experimentally, we found 100% inhibition up to 60 nM and 84% average inhibition at 30 nM in SARS-CoV-2 live viral assays. MLN was also 10× more potent than remdesivir and molnupiravir. MLN’s toxicity against human alveolar cell line A549, immortalized human fetal renal cell line HEK293, and human hepatoma cell line Huh7.1 were 17.12%, 40.30%, and 36.25%, respectively. The cytotoxicity IC50 breakpoint ratio versus anti-SARS-CoV-2 activity was more than 65-fold. The IC50 values against the alpha, delta, and Omicron variants were all below 0.020 µM, and 134.6 nM of MLN had 100% inhibition in an entry and spread assays. MLN is eclectic in its actions through its binding to Sec61, AT2R, and the novel fusion protein, making it a good drug candidate for treating and preventing COVID-19 and other similarly transmitted enveloped viruses and pathogens.
- Published
- 2023
- Full Text
- View/download PDF
16. Inhibition of the SEC61 translocon by mycolactone induces a protective autophagic response controlled by EIF2S1-dependent translation that does not require ULK1 activity.
- Author
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Hall, Belinda S, Dos Santos, Scott J, Hsieh, Louise Tzung-Harn, Manifava, Maria, Ruf, Marie-Thérèse, Pluschke, Gerd, Ktistakis, Nicholas, and Simmonds, Rachel E
- Subjects
PROTEOLYSIS ,GREEN fluorescent protein ,PROTEASOMES ,TUBULINS ,BURULI ulcer ,HYPOXIA-inducible factor 1 ,ENDOPLASMIC reticulum ,CELL survival - Abstract
The Mycobacterium ulcerans exotoxin, mycolactone, is responsible for the immunosuppression and tissue necrosis that characterizes Buruli ulcer. Mycolactone inhibits SEC61-dependent co-translational translocation of proteins into the endoplasmic reticulum and the resultant cytosolic translation triggers degradation of mislocalized proteins by the ubiquitin-proteasome system. Inhibition of SEC61 by mycolactone also activates multiple EIF2S1/eIF2α kinases in the integrated stress response (ISR). Here we show mycolactone increased canonical markers of selective macroautophagy/autophagy LC3B-II, ubiquitin and SQSTM1/p62 in diverse disease-relevant primary cells and cell lines. Increased formation of puncta positive for the early autophagy markers WIPI2, RB1CC1/FIP200 and ATG16L1 indicates increased initiation of autophagy. The mycolactone response was SEC61A1-dependent and involved a pathway that required RB1CC1 but not ULK. Deletion of Sqstm1 reduced cell survival in the presence of mycolactone, suggesting this response protects against the increased cytosolic protein burden caused by the toxin. However, reconstitution of baseline SQSTM1 expression in cells lacking all autophagy receptor proteins could not rescue viability. Translational regulation by EIF2S1 in the ISR plays a key role in the autophagic response to mycolactone. Mycolactone-dependent induction of SQSTM1 was reduced in eif2ak3
−/- /perk−/- cells while the p-EIF2S1 antagonist ISRIB reversed the upregulation of SQSTM1 and reduced RB1CC1, WIPI2 and LC3B puncta formation. Increased SQSTM1 staining could be seen in Buruli ulcer patient skin biopsy samples, reinforcing genetic data that suggests autophagy is relevant to disease pathology. Since selective autophagy and the ISR are both implicated in neurodegeneration, cancer and inflammation, the pathway uncovered here may have a broad relevance to human disease. Abbreviations: ATF4: activating transcription factor 4; ATG: autophagy related; BAF: bafilomycin A1 ; ATG16L1: autophagy related 16 like 1; BU: Buruli ulcer; CQ: chloroquine; EIF2AK3: eukaryotic translation initiation factor 2 alpha kinase 3; CALCOCO2: calcium binding and coiled-coil domain 2; DMSO: dimethyl sulfoxide; EIF2S1: eukaryotic translation initiation factor 2 subunit alpha; ER: endoplasmic reticulum; GFP: green fluorescent protein; HDMEC: human dermal microvascular endothelial cells; HFFF: human fetal foreskin fibroblasts; ISR: integrated stress response; ISRIB: integrated stress response inhibitor; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; Myco: mycolactone; NBR1: NBR1 autophagy cargo receptor; NFE2L2: nuclear factor, erythroid 2 like 2; OPTN: optineurin; PFA: paraformaldehyde; PtdIns3P: phosphatidylinositol-3-phosphate; RB1CC1: RB1-inducible coiled coil 1; SQSTM1: sequestosome 1; TAX1BP1: Tax1 binding protein 1; ULK: unc-51 like autophagy activating kinase; UPS: ubiquitin-proteasome system; WIPI: WD repeat domain, phosphoinositide interacting; WT: wild type. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
17. Induced Synthesis of Mycolactone Restores the Pathogenesis of Mycobacterium ulcerans In Vitro and In Vivo.
- Author
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Strong, Emily, Hart, Bryan, Wang, Jia, Orozco, Maria Gonzalez, and Lee, Sunhee
- Subjects
BURULI ulcer ,MYCOBACTERIUM ,MYCOBACTERIAL diseases ,RAPAMYCIN ,TETRACYCLINES ,PATHOGENESIS ,CELLULAR signal transduction ,BACTERIAL diseases - Abstract
Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU), the third most common mycobacterial infection. Virulent M. ulcerans secretes mycolactone, a polyketide toxin. Most observations of M. ulcerans infection are described as an extracellular milieu in the form of a necrotic ulcer. While some evidence exists of an intracellular life cycle for M. ulcerans during infection, the exact role that mycolactone plays in this process is poorly understood. Many previous studies have relied upon the addition of purified mycolactone to cell-culture systems to study its role in M. ulcerans pathogenesis and host-response modulation. However, this sterile system drastically simplifies the M. ulcerans infection model and assumes that mycolactone is the only relevant virulence factor expressed by M. ulcerans. Here we show that the addition of purified mycolactone to macrophages during M. ulcerans infection overcomes the bacterial activation of the mechanistic target of rapamycin (mTOR) signaling pathway that plays a substantial role in regulating different cellular processes, including autophagy and apoptosis. To further study the role of mycolactone during M. ulcerans infection, we have developed an inducible mycolactone expression system. Utilizing the mycolactone-deficient Mul ::Tn118 strain that contains a transposon insertion in the putative beta-ketoacyl transferase (mup045), we have successfully restored mycolactone production by expressing mup045 in a tetracycline-inducible vector system, which overcomes in-vitro growth defects associated with constitutive complementation. The inducible mycolactone-expressing bacteria resulted in the establishment of infection in a murine footpad model of BU similar to that observed during the infection with wild-type M. ulcerans. This mycolactone inducible system will allow for further analysis of the roles and functions of mycolactone during M. ulcerans infection. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
18. Induced Synthesis of Mycolactone Restores the Pathogenesis of Mycobacterium ulcerans In Vitro and In Vivo
- Author
-
Emily Strong, Bryan Hart, Jia Wang, Maria Gonzalez Orozco, and Sunhee Lee
- Subjects
Buruli ulcer ,mycobacteria ,macrophages ,mycolactone ,host–microbe interaction ,cytotoxicity ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU), the third most common mycobacterial infection. Virulent M. ulcerans secretes mycolactone, a polyketide toxin. Most observations of M. ulcerans infection are described as an extracellular milieu in the form of a necrotic ulcer. While some evidence exists of an intracellular life cycle for M. ulcerans during infection, the exact role that mycolactone plays in this process is poorly understood. Many previous studies have relied upon the addition of purified mycolactone to cell-culture systems to study its role in M. ulcerans pathogenesis and host-response modulation. However, this sterile system drastically simplifies the M. ulcerans infection model and assumes that mycolactone is the only relevant virulence factor expressed by M. ulcerans. Here we show that the addition of purified mycolactone to macrophages during M. ulcerans infection overcomes the bacterial activation of the mechanistic target of rapamycin (mTOR) signaling pathway that plays a substantial role in regulating different cellular processes, including autophagy and apoptosis. To further study the role of mycolactone during M. ulcerans infection, we have developed an inducible mycolactone expression system. Utilizing the mycolactone-deficient Mul::Tn118 strain that contains a transposon insertion in the putative beta-ketoacyl transferase (mup045), we have successfully restored mycolactone production by expressing mup045 in a tetracycline-inducible vector system, which overcomes in-vitro growth defects associated with constitutive complementation. The inducible mycolactone-expressing bacteria resulted in the establishment of infection in a murine footpad model of BU similar to that observed during the infection with wild-type M. ulcerans. This mycolactone inducible system will allow for further analysis of the roles and functions of mycolactone during M. ulcerans infection.
- Published
- 2022
- Full Text
- View/download PDF
19. The One That Got Away: How Macrophage-Derived IL-1β Escapes the Mycolactone-Dependent Sec61 Blockade in Buruli Ulcer.
- Author
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Hall, Belinda S., Hsieh, Louise Tzung-Harn, Sacre, Sandra, and Simmonds, Rachel E.
- Subjects
BURULI ulcer ,PATHOLOGY ,EXOTOXIN ,ANTIGEN presentation ,BLOCKADE ,SKIN regeneration ,T cells ,IMMUNE system - Abstract
Buruli ulcer (BU), caused by Mycobacterium ulcerans , is a devastating necrotizing skin disease. Key to its pathogenesis is mycolactone, the exotoxin virulence factor that is both immunosuppressive and cytotoxic. The discovery that the essential Sec61 translocon is the major cellular target of mycolactone explains much of the disease pathology, including the immune blockade. Sec61 inhibition leads to a loss in production of nearly all cytokines from monocytes, macrophages, dendritic cells and T cells, as well as antigen presentation pathway proteins and costimulatory molecules. However, there has long been evidence that the immune system is not completely incapable of responding to M. ulcerans infection. In particular, IL-1β was recently shown to be present in BU lesions, and to be induced from M. ulcerans -exposed macrophages in a mycolactone-dependent manner. This has important implications for our understanding of BU, showing that mycolactone can act as the "second signal" for IL-1β production without inhibiting the pathways of unconventional secretion it uses for cellular release. In this Perspective article, we validate and discuss this recent advance, which is entirely in-line with our understanding of mycolactone's inhibition of the Sec61 translocon. However, we also show that the IL-1 receptor, which uses the conventional secretory pathway, is sensitive to mycolactone blockade at Sec61. Hence, a more complete understanding of the mechanisms regulating IL-1β function in skin tissue, including the transient intra-macrophage stage of M. ulcerans infection, is urgently needed to uncover the double-edged sword of IL-1β in BU pathogenesis, treatment and wound healing. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
20. Systematic review of M. Bovis BCG and other candidate vaccines for Buruli ulcer prophylaxis.
- Author
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Muhi, Stephen and Stinear, Timothy P.
- Subjects
- *
BURULI ulcer , *NEGLECTED diseases , *MYCOBACTERIUM bovis , *VACCINES , *RANDOMIZED controlled trials - Abstract
Buruli ulcer, caused by Mycobacterium ulcerans, is a neglected tropical disease endemic to over 30 countries, with increasing incidence in temperate, coastal Victoria, Australia. Strategies to control transmission are urgently required. This study systematically reviews the literature to identify and describe candidate prophylactic Buruli ulcer vaccines. This review highlights that Mycobacterium bovis Bacillus Calmette-Guérin (BCG) vaccine is the only vaccine studied in randomised controlled trials and confirms its importance as a benchmark for comparison against putative vaccines in pre-clinical studies. Nevertheless, BCG alone is unable to offer long-term protection in humans. A number of experimental vaccines that exceed the protection provided by BCG in mice have emerged, particularly those utilising recombinant BCG expressing immunogenic M. ulcerans proteins. Although progress is promising, there remain key questions about the optimal approach to characterising the immunological correlates of protection in humans and strategies to investigate the safety and efficacy of such vaccines in humans. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
21. Transcriptional adaptation of Mycobacterium ulcerans in an original mouse model: New insights into the regulation of mycolactone.
- Author
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Robbe-Saule, Marie, Foulon, Mélanie, Poncin, Isabelle, Esnault, Lucille, Varet, Hugo, Legendre, Rachel, Besnard, Alban, Grzegorzewicz, Anna E., Jackson, Mary, Canaan, Stéphane, Marsollier, Laurent, and Marion, Estelle
- Subjects
- *
LABORATORY mice , *MYCOBACTERIUM , *ANIMAL disease models , *BURULI ulcer , *BACTERIAL adaptation , *MYCOBACTERIAL diseases , *HEALING , *PHYSIOLOGICAL adaptation - Abstract
Mycobacterium ulcerans is the causal agent of Buruli ulcer, a chronic infectious disease and the third most common mycobacterial disease worldwide. Without early treatment, M. ulcerans provokes massive skin ulcers, caused by the mycolactone toxin, its main virulence factor. However, spontaneous healing may occur in Buruli ulcer patients several months or years after the disease onset. We have shown, in an original mouse model, that bacterial load remains high and viable in spontaneously healed tissues, with a switch of M. ulcerans to low levels of mycolactone production, adapting its strategy to survive in such a hostile environment. This original model offers the possibility to investigate the regulation of mycolactone production, by using an RNA-seq strategy to study bacterial adaptation during mouse infection. Pathway analysis and characterization of the tissue environment showed that the bacillus adapted to its new environment by modifying its metabolic activity and switching nutrient sources. Thus, M. ulcerans ensures its survival in healing tissues by reducing its secondary metabolism, leading to an inhibition of mycolactone synthesis. These findings shed new light on mycolactone regulation and pave the way for new therapeutic strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
22. Ketogenic Diet Impairment of Mycobacterium ulcerans Growth and Toxin Production and Enhancement of Host Response to Infection in an Experimental Mouse Model.
- Author
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Foulon, Mélanie, Robbe-Saule, Marie, Esnault, Lucille, Malloci, Marine, Mery, Anthony, Saint-André, Jean-Paul, Croue, Anne, Kempf, Marie, Homedan, Chadi, Marion, Estelle, and Marsollier, Laurent
- Subjects
- *
BURULI ulcer , *KETOGENIC diet , *LABORATORY mice , *ANIMAL disease models , *MYCOBACTERIUM , *SKIN diseases , *3-Hydroxybutyric acid , *WOUND healing , *BIOLOGICAL models , *RESEARCH , *ANIMAL experimentation , *EVALUATION research , *COMPARATIVE studies , *GRAM-positive bacteria , *MACROLIDE antibiotics , *MICE - Abstract
Ketogenic diets have been used to treat diverse conditions, and there is growing evidence of their benefits for tissue repair and in inflammatory disease treatment. However, their role in infectious diseases has been little studied. Buruli ulcer (Mycobacterium ulcerans infection) is a chronic infectious disease characterized by large skin ulcerations caused by mycolactone, the major virulence factor of the bacillus. In the current study, we investigated the impact of ketogenic diet on this cutaneous disease in an experimental mouse model. This diet prevented ulceration, by modulating bacterial growth and host inflammatory response. β-hydroxybutyrate, the major ketone body produced during ketogenic diet and diffusing in tissues, impeded M. ulcerans growth and mycolactone production in vitro underlying its potential key role in infection. These results pave the way for the development of new patient management strategies involving shorter courses of treatment and improving wound healing, in line with the major objectives of the World Health Organization. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
23. The One That Got Away: How Macrophage-Derived IL-1β Escapes the Mycolactone-Dependent Sec61 Blockade in Buruli Ulcer
- Author
-
Belinda S. Hall, Louise Tzung-Harn Hsieh, Sandra Sacre, and Rachel E. Simmonds
- Subjects
Buruli ulcer ,Mycobacterium ulcerans ,mycolactone ,IL-1β ,Sec61 ,protein translocation ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Buruli ulcer (BU), caused by Mycobacterium ulcerans, is a devastating necrotizing skin disease. Key to its pathogenesis is mycolactone, the exotoxin virulence factor that is both immunosuppressive and cytotoxic. The discovery that the essential Sec61 translocon is the major cellular target of mycolactone explains much of the disease pathology, including the immune blockade. Sec61 inhibition leads to a loss in production of nearly all cytokines from monocytes, macrophages, dendritic cells and T cells, as well as antigen presentation pathway proteins and costimulatory molecules. However, there has long been evidence that the immune system is not completely incapable of responding to M. ulcerans infection. In particular, IL-1β was recently shown to be present in BU lesions, and to be induced from M. ulcerans-exposed macrophages in a mycolactone-dependent manner. This has important implications for our understanding of BU, showing that mycolactone can act as the “second signal” for IL-1β production without inhibiting the pathways of unconventional secretion it uses for cellular release. In this Perspective article, we validate and discuss this recent advance, which is entirely in-line with our understanding of mycolactone’s inhibition of the Sec61 translocon. However, we also show that the IL-1 receptor, which uses the conventional secretory pathway, is sensitive to mycolactone blockade at Sec61. Hence, a more complete understanding of the mechanisms regulating IL-1β function in skin tissue, including the transient intra-macrophage stage of M. ulcerans infection, is urgently needed to uncover the double-edged sword of IL-1β in BU pathogenesis, treatment and wound healing.
- Published
- 2022
- Full Text
- View/download PDF
24. Bacterial diversity in Buruli ulcer lesions in Ghana.
- Author
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Ackam N, Opoku-Boadi A, Agbavor B, Adjei JK, Agbanyo A, Oppong MN, Wiafe-Akenten C, Sylverken A, Obiri-Danso K, Wansbrough-Jones M, Amoako YA, and Phillips RO
- Abstract
Background: Previous studies have demonstrated secondary microbial infection of Buruli ulcer (BUD) lesions before, during and after treatment. However, there is limited data on the bacterial diversity across treatment and their influence on clinical outcome. The present study aimed to investigate the relationship between bacterial diversity within BUD lesions and clinical outcome in affected individuals., Methods: We investigated the bacterial diversity within lesions of individuals with PCR confirmed BUD from 5 endemic districts within central Ghana. Samples were collected longitudinally from lesions over treatment period. Microbiological analyses including isolation of bacteria, and species identification were performed using the VITEK 2 compact., Results: Out of 36 participants included, 80.5 % presented with ulcers on the lower limbs. Higher bacterial diversity was observed in ulcers compared to other clinical forms of BUD. There was a significant association between bacterial diversity and clinical outcome ( p = 0.002). ESBL producing bacteria and MRSA were isolated in slow healing BUD lesions., Conclusion: Higher diversity of secondary organisms colonizing BUD lesions may have an impact on clinical outcome in affected individuals. There is the need for the development of treatment guidelines for simultaneous management of M. ulcerans and other potential pathogens within lesions to improve clinical outcome., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)
- Published
- 2024
- Full Text
- View/download PDF
25. Molecular Mechanisms Underpinning the Circulation and Cellular Uptake of Mycobacterium ulcerans Toxin Mycolactone.
- Author
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Tello Rubio, Bruno, Bugault, Florence, Baudon, Blandine, Raynal, Bertrand, Brûlé, Sébastien, Morel, Jean-David, Saint-Auret, Sarah, Blanchard, Nicolas, Demangel, Caroline, and Guenin-Macé, Laure
- Subjects
MYCOBACTERIUM ,BLOOD lipoproteins ,BURULI ulcer ,SERUM albumin ,TOXINS ,BIOAVAILABILITY ,SOLUBILIZATION - Abstract
Mycolactone is a diffusible lipid toxin produced by Mycobacterium ulcerans, the causative agent of Buruli ulcer disease. Altough bacterially derived mycolactone has been shown to traffic from cutaneous foci of infection to the bloodstream, the mechanisms underpinning its access to systemic circulation and import by host cells remain largely unknown. Using biophysical and cell-based approaches, we demonstrate that mycolactone specific association to serum albumin and lipoproteins is necessary for its solubilization and is a major mechanism to regulate its bioavailability. We also demonstrate that Scavenger Receptor (SR)-B1 contributes to the cellular uptake of mycolactone. Overall, we suggest a new mechanism of transport and cell entry, challenging the dogma that the toxin enters host cells via passive diffusion. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
26. Molecular Mechanisms Underpinning the Circulation and Cellular Uptake of Mycobacterium ulcerans Toxin Mycolactone
- Author
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Bruno Tello Rubio, Florence Bugault, Blandine Baudon, Bertrand Raynal, Sébastien Brûlé, Jean-David Morel, Sarah Saint-Auret, Nicolas Blanchard, Caroline Demangel, and Laure Guenin-Macé
- Subjects
mycolactone ,Mycobacterium ulcerans ,lipid carriers ,SR-B1 ,uptake ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Mycolactone is a diffusible lipid toxin produced by Mycobacterium ulcerans, the causative agent of Buruli ulcer disease. Altough bacterially derived mycolactone has been shown to traffic from cutaneous foci of infection to the bloodstream, the mechanisms underpinning its access to systemic circulation and import by host cells remain largely unknown. Using biophysical and cell-based approaches, we demonstrate that mycolactone specific association to serum albumin and lipoproteins is necessary for its solubilization and is a major mechanism to regulate its bioavailability. We also demonstrate that Scavenger Receptor (SR)-B1 contributes to the cellular uptake of mycolactone. Overall, we suggest a new mechanism of transport and cell entry, challenging the dogma that the toxin enters host cells via passive diffusion.
- Published
- 2021
- Full Text
- View/download PDF
27. Immunity against Mycobacterium ulcerans: The subversive role of mycolactone.
- Author
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Demangel, Caroline
- Subjects
- *
MYCOBACTERIUM , *BURULI ulcer , *IMMUNITY , *MEMBRANE proteins , *EUKARYOTIC cells - Abstract
Summary: Mycobacterium ulcerans causes Buruli ulcer, a neglected tropical skin disease manifesting as chronic wounds that can leave victims with major, life‐long deformity and disability. Differently from other mycobacterial pathogens, M ulcerans produces mycolactone, a diffusible lipid factor with unique cytotoxic and immunomodulatory properties. Both traits result from mycolactone targeting Sec61, the entry point of the secretory pathway in eukaryotic cells. By inhibiting Sec61, mycolactone prevents the host cell's production of secreted proteins, and most of its transmembrane proteins. This molecular blockade dramatically alters the functions of immune cells, thereby the generation of protective immunity. Moreover, sustained inhibition of Sec61 triggers proteotoxic stress responses leading to apoptotic cell death, which can stimulate vigorous immune responses. The dynamics of bacterial production of mycolactone and elimination by infected hosts thus critically determine the balance between its immunostimulatory and immunosuppressive effects. Following an introduction summarizing the essential information on Buruli ulcer disease, this review focuses on the current state of knowledge regarding mycolactone's regulation and biodistribution. We then detail the consequences of mycolactone‐mediated Sec61 blockade on initiation and maintenance of innate and adaptive immune responses. Finally, we discuss the key questions to address in order to improve immunity to M ulcerans, and how increased knowledge of mycolactone biology may pave the way to innovative therapeutics. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
28. Density Functional Theory-Based Studies Predict Carbon Nanotubes as Effective Mycolactone Inhibitors
- Author
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Nafiu Suleiman, Abu Yaya, Michael D. Wilson, Solomon Aryee, and Samuel K. Kwofie
- Subjects
mycolactone ,nanotubes ,density functional theory (DFT) ,boron nitride nanotubes (BNNTs) ,carbon nanotubes (CNTs) ,HOMO–LUMO orbital ,Organic chemistry ,QD241-441 - Abstract
Fullerenes, boron nitride nanotubes (BNNTs), and carbon nanotubes (CNTs) have all been extensively explored for biomedical purposes. This work describes the use of BNNTs and CNTs as mycolactone inhibitors. Density functional theory (DFT) has been used to investigate the chemical properties and interaction mechanisms of mycolactone with armchair BNNTs (5,5) and armchair CNTs (5,5). By examining the optimized structure and interaction energy, the intermolecular interactions between mycolactone and nanotubes were investigated. The findings indicate that mycolactone can be physically adsorbed on armchair CNTs in a stable condition, implying that armchair CNTs can be potential inhibitors of mycolactone. According to DOS plots and HOMO–LUMO orbital studies, the electronic characteristics of pure CNTs are not modified following mycolactone adsorption on the nanotubes. Because of mycolactone’s large π-π interactions with CNTs, the estimated interaction energies indicate that mycolactone adsorption on CNTs is preferable to that on BNNTs. CNTs can be explored as potentially excellent inhibitors of mycolactone toxins in biological systems.
- Published
- 2022
- Full Text
- View/download PDF
29. Mycobacterium ulcerans Infection
- Author
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Bonamonte, Domenico, Filoni, Angela, Angelini, Gianni, Bonamonte, Domenico, editor, and Angelini, Gianni, editor
- Published
- 2017
- Full Text
- View/download PDF
30. Co-infection of HIV in patients with Buruli ulcer disease in Central Ghana.
- Author
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Amoako, Yaw Ampem, Loglo, Aloysius Dzigbordi, Frimpong, Michael, Agbavor, Bernadette, Abass, Mohammed Kabiru, Amofa, George, Ofori, Elizabeth, Ampadu, Edwin, Asiedu, Kingsley, Stienstra, Ymkje, Wansbrough-Jones, Mark, van der Werf, Tjip, and Phillips, Richard Odame
- Subjects
- *
HIV-positive persons , *MIXED infections , *REVERSE transcriptase , *VIRAL load , *CD4 lymphocyte count , *HIV infection epidemiology , *HIV infections , *WOUND healing , *RNA , *RETROSPECTIVE studies , *BACTERIAL growth , *MICROBIOLOGICAL techniques , *DISEASE prevalence , *QUESTIONNAIRES , *RESEARCH funding , *POLYMERASE chain reaction , *BURULI ulcer , *GRAM-positive bacteria - Abstract
Background: Previous studies have reported that presence and severity of Buruli ulcer (BU) may reflect the underlying immunosuppression in HIV infected individuals by causing increased incidence of multiple, larger and ulcerated lesions. We report cases of BU-HIV coinfection and the accompanying programmatic challenges encountered in central Ghana.Methods: Patients with PCR confirmed BU in central Ghana who were HIV positive were identified and their BU01 forms were retrieved and reviewed in further detail. A combined 16S rRNA reverse transcriptase / IS2404 qPCR assay was used to assess the Mycobacterium ulcerans load. The characteristics of coinfected patients (BU+HIV+) were compared with a group of matched controls.Results: The prevalence of HIV in this BU cohort was 2.4% (compared to national HIV prevalence of 1.7%). Eight of 9 BU+HIV+ patients had a single lesion and ulcers were the most common lesion type. The lesions presented were predominantly category II (5/9) followed by category I lesions. The median (IQR) time to healing was 14 (8-28) weeks in the BU+HIV+ compared to 28 (12-33) weeks in the control BU+HIV- group (p = 0.360). Only one BU+HIV+ developed a paradoxical reaction at week 16 but the lesion healed completely at week 20. The median bacterial load (16SrRNA) of BU+HIV+ patients was 750 copies /ml (95% CI 0-398,000) versus 500 copies/ml (95% CI 0-126,855,500) in BU+HIV- group. Similarly, the median count using the IS2404 assay was 500 copies/ml (95% CI 0-500) for BU+HIV+ patients versus 500 copies/ml (95% CI 500-31,000) for BU+HIV- patients. BU+HIV- patients mounted a significantly higher interferon-γ response compared to the BU+HIV+ co-infected patients with respective median (range) responses of [1687(81.11-4399) pg/ml] versus [137.5(4.436-1406) pg/ml, p = 0.03]. There were challenges with the integration of HIV and BU care in this cohort.Conclusion: The prevalence of HIV in the BU+ infected population was not significantly increased when compared to the prevalence of HIV in the general population. There was no clear relationship between BU lesion severity and HIV viral load or CD4 counts. Efforts should be made to encourage the integration of care of patients with BU-HIV coinfection. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
31. Mycobacterium ulcerans-specific immune response after immunisation with bacillus Calmette-Guérin (BCG) vaccine.
- Author
-
Pittet, Laure F., Tebruegge, Marc, Dutta, Binita, Donath, Susan, Messina, Nicole, Casalaz, Dan, Hanekom, Willem A., Britton, Warwick J., Robins-Browne, Roy, Curtis, Nigel, and Ritz, Nicole
- Subjects
- *
IMMUNE response , *IMMUNIZATION , *MYCOBACTERIUM , *BURULI ulcer , *BCG vaccines , *MATERNALLY acquired immunity - Abstract
• Infant BCG immunisation induces M. ulcerans -specific immune responses. • M. ulcerans - and M. tuberculosis -specific immune responses are qualitatively similar. • Magnitude of M. ulcerans -specific immune responses was not influenced by BCG strain. • These in-vitro findings support the protective effect observed epidemiologically. Bacillus Calmette–Guérin (BCG) vaccine provides partial protection against Buruli ulcer caused by Mycobacterium ulcerans in epidemiological studies. This study aimed to quantify M. ulcerans -specific immune responses induced by BCG immunisation. Intracellular cytokine analysis of in-vitro experiments done 10 weeks after BCG immunisation in 130 Australian infants randomised to one of three BCG vaccine strains given either at birth (BCG-Denmark, BCG-Japan, or BCG-Russia) or at two months of age (BCG-Denmark). Proportions of polyfunctional CD4+ T-cells were higher in M. ulcerans -stimulated compared to unstimulated control samples. These proportions were not influenced by the vaccine strain or timing of the immunisation. The M. ulcerans -specific immune responses showed similar patterns to those observed in M. tuberculosis -stimulated samples, although they were of lower magnitude. Our data show that BCG immunisation induces M. ulcerans -specific immune responses in infants, likely explaining the cross-protective effect observed in epidemiological studies. (ACTRN12608000227392) [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
32. Buruli ulcer: The Efficacy of Innate Immune Defense May Be a Key Determinant for the Outcome of Infection With Mycobacterium ulcerans
- Author
-
Katharina Röltgen and Gerd Pluschke
- Subjects
Mycobacterium ulcerans ,skin neglected tropical disease ,mycolactone ,Mycobacterium marinum ,zebrafish ,Microbiology ,QR1-502 - Abstract
Buruli ulcer (BU) is a neglected, tropical infectious disease of the skin and the subcutaneous tissue caused by Mycobacterium ulcerans. This pathogen has emerged as a new species from a common ancestor with Mycobacterium marinum by acquisition of the virulence plasmid pMUM. The plasmid encodes enzymes required for the synthesis of the macrolide toxin mycolactone, which has cytotoxic and immunosuppressive activities. In advanced BU lesions, extracellular clusters of M. ulcerans reside in necrotic subcutaneous tissue and are protected from infiltrating leukocytes by the cytotoxic activity of secreted mycolactone. Several lines of evidence indicate that elements of the innate immune system eliminate in many cases the initial inoculum before bacterial clusters can form and that therefore exposure to M. ulcerans leads only in a minority of individuals to the characteristic chronic necrotizing BU lesions. It is assumed that phagocytes play a key role in early host defense against M. ulcerans. Antibodies against bacterial surface structures seem to have less potential to enhance innate immunity than TH1 cell responses. Precise innate and adaptive immune effector mechanisms leading to protective immunity are however unclear, complicating the development of effective vaccines, the most desired solution to control BU. The tuberculosis vaccine Mycobacterium bovis Bacillus Calmette–Guérin (BCG) has limited short-term protective activity against BU. Whether this effect is due to the broad antigenic cross-reactivity between M. bovis and M. ulcerans or is at least partly mediated by a non-specific enhanced responsiveness of innate immune cells to secondary stimulation, recently described as “trained immunity” or “innate immune memory” is unknown but has major implications for vaccine design. Current vaccine research and development activities are focusing on recombinant BCG, subunit vaccines with selected M. ulcerans proteins, and the neutralization of mycolactone.
- Published
- 2020
- Full Text
- View/download PDF
33. Buruli ulcer: The Efficacy of Innate Immune Defense May Be a Key Determinant for the Outcome of Infection With Mycobacterium ulcerans.
- Author
-
Röltgen, Katharina and Pluschke, Gerd
- Subjects
BURULI ulcer ,MYCOBACTERIUM bovis ,MYCOBACTERIAL diseases ,BACTERIAL antibodies ,IMMUNOLOGIC memory ,VACCINE effectiveness ,PLASMIDS ,TUBERCULOSIS in cattle - Abstract
Buruli ulcer (BU) is a neglected, tropical infectious disease of the skin and the subcutaneous tissue caused by Mycobacterium ulcerans. This pathogen has emerged as a new species from a common ancestor with Mycobacterium marinum by acquisition of the virulence plasmid pMUM. The plasmid encodes enzymes required for the synthesis of the macrolide toxin mycolactone, which has cytotoxic and immunosuppressive activities. In advanced BU lesions, extracellular clusters of M. ulcerans reside in necrotic subcutaneous tissue and are protected from infiltrating leukocytes by the cytotoxic activity of secreted mycolactone. Several lines of evidence indicate that elements of the innate immune system eliminate in many cases the initial inoculum before bacterial clusters can form and that therefore exposure to M. ulcerans leads only in a minority of individuals to the characteristic chronic necrotizing BU lesions. It is assumed that phagocytes play a key role in early host defense against M. ulcerans. Antibodies against bacterial surface structures seem to have less potential to enhance innate immunity than T
H 1 cell responses. Precise innate and adaptive immune effector mechanisms leading to protective immunity are however unclear, complicating the development of effective vaccines, the most desired solution to control BU. The tuberculosis vaccine Mycobacterium bovis Bacillus Calmette–Guérin (BCG) has limited short-term protective activity against BU. Whether this effect is due to the broad antigenic cross-reactivity between M. bovis and M. ulcerans or is at least partly mediated by a non-specific enhanced responsiveness of innate immune cells to secondary stimulation, recently described as "trained immunity" or "innate immune memory" is unknown but has major implications for vaccine design. Current vaccine research and development activities are focusing on recombinant BCG, subunit vaccines with selected M. ulcerans proteins, and the neutralization of mycolactone. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
34. Infección por Mycobacterium ulcerans. Úlcera de Buruli.
- Author
-
Galván-Lewit, Fernando Benjamín, Calderón, Luz, Ponce-Olivera, Rosa María, and Bonifaz, Alexandro
- Abstract
Buruli ulcer is a devastating disease caused by Mycobacterium ulcerans, its incidence has increased over the past decades becoming the third most common mycobacterial infection in the world. It usually presents as extensive non-painful ulcers commonly found on legs and arms. The confirmatory diagnosis is made mainly by PCR test; microscopic examination and cultures are also confirmatory, although they show lower sensitivity. The treatment should always include a pharmacological component with rifampin and clarithromycin, in addition to proper wound management. Mycobacterium ulcerans infection lesions tend to chronicity and confer high morbidity secondary to the pronounced disfigurement and social stigma. [ABSTRACT FROM AUTHOR]
- Published
- 2020
35. Mycolactone as Analgesic: Subcutaneous Bioavailability Parameters
- Author
-
Jérémie Babonneau, Dimitri Bréard, Marie-Line Reynaert, Estelle Marion, David Guilet, Jean-Paul Saint André, Anne Croué, Priscille Brodin, Pascal Richomme, and Laurent Marsollier
- Subjects
Mycobacterium ulcerans ,mycolactone ,analgesia ,bioavailability ,biological action ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Mycobacterium ulcerans is the bacillus responsible for Buruli ulcer, an infectious disease and the third most important mycobacterial disease worldwide, after tuberculosis and leprosy. M. ulcerans infection is a type of panniculitis beginning mostly with a nodule or an oedema, which can progress to large ulcerative lesions. The lesions are caused by mycolactone, the polyketide toxin of M. ulcerans. Mycolactone plays a central role for host colonization as it has immunomodulatory and analgesic effects. On one hand, mycolactone induces analgesia by targeting type-2 angiotensin II receptors (AT2R), causing cellular hyperpolarization and neuron desensitization. Indeed, a single subcutaneous injection of mycolactone into the mouse footpad induces a long-lasting hypoesthesia up to 48 h. It was suggested that the long-lasting hypoesthesia may result from the persistence of a significant amount of mycolactone locally following its injection, which could be probably due to its slow elimination from tissues. To verify this hypothesis, we investigated the correlation between hypoesthesia and mycolactone bioavailability directly at the tissue level. Various quantities of mycolactone were then injected in mouse tissue and hypoesthesia was recorded with nociception assays over a period of 48 h. The hypoesthesia was maximal 6 h after the injection of 4 μg mycolactone. The basal state was reached 48 h after injection, which demonstrated the absence of nerve damage. Surprisingly, mycolactone levels decreased strongly during the first hours with a reduction of 70 and 90% after 4 and 10 h, respectively. Also, mycolactone did not diffuse in neighboring skin tissue and only poorly into the bloodstream upon direct injection. Nevertheless, the remaining amount was sufficient to induce hypoesthesia during 24 h. Our results thus demonstrate that intact mycolactone is rapidly eliminated and that very small amounts of mycolactone are sufficient to induce hypoesthesia. Taken together, our study points out that mycolactone ought to be considered as a promising analgesic.
- Published
- 2019
- Full Text
- View/download PDF
36. Molecular Docking and Dynamics Simulation Studies Predict Munc18b as a Target of Mycolactone: A Plausible Mechanism for Granule Exocytosis Impairment in Buruli Ulcer Pathogenesis.
- Author
-
Kwofie, Samuel K., Dankwa, Bismark, Enninful, Kweku S., Adobor, Courage, Broni, Emmanuel, Ntiamoah, Alfred, and Wilson, Michael D.
- Abstract
Ulcers due to infections with Mycobacterium ulcerans are characterized by complete lack of wound healing processes, painless, an underlying bed of host dead cells and undermined edges due to necrosis. Mycolactone, a macrolide produced by the mycobacterium, is believed to be the toxin responsible. Of interest and relevance is the knowledge that Buruli ulcer (BU) patients remember experiencing trauma previously at the site of the ulcers, suggesting an impairment of wound healing processes, the plausible effect due to the toxin. Wound healing processes involve activation of the blood platelets to release the contents of the dense granules mainly serotonin, calcium ions, and ADP/ATP by exocytosis into the bloodstream. The serotonin release results in attracting more platelets and mast cells to the wound site, with the mast cells also undergoing degranulation, releasing compounds into the bloodstream by exocytosis. Recent work has identified interference in the co-translational translocation of many secreted proteins via the endoplasmic reticulum and cell death involving Wiskott-Aldrich syndrome protein (WASP), Sec61, and angiotensin II receptors (AT2R). We hypothesized that mycolactone by being lipophilic, passively crosses cell membranes and binds to key proteins that are involved in exocytosis by platelets and mast cells, thus inhibiting the initiation of wound healing processes. Based on this, molecular docking studies were performed with mycolactone against key soluble n-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and regulators, namely Vesicle-associated membrane protein (VAMP8), Synaptosomal-associated protein (SNAP23, syntaxin 11, Munc13-4 (its isoform Munc13-1 was used), and Munc18b; and also against known mycolactone targets (Sec61, AT2R, and WASP). Munc18b was shown to be a plausible mycolactone target after the molecular docking studies with binding affinity of -8.5 kcal/mol. Structural studies and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding energy calculations of the mycolactone and Munc18b complex was done with 100 ns molecular dynamics simulations using GROMACS. Mycolactone binds strongly to Munc18b with an average binding energy of -247.571 ± 37.471 kJ/mol, and its presence elicits changes in the structural conformation of the protein. Analysis of the binding interactions also shows that mycolactone interacts with Arg405, which is an important residue of Munc18b, whose mutation could result in impaired granule exocytosis. These findings consolidate the possibility that Munc18b could be a target of mycolactone. The implication of the interaction can be experimentally evaluated to further understand its role in granule exocytosis impairment in Buruli ulcer. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
37. Challenges associated with the treatment of Buruli ulcer.
- Author
-
Aboagye, Sammy Yaw, Kpeli, Grace, Tuffour, Joseph, and Yeboah‐Manu, Dorothy
- Subjects
BURULI ulcer ,MYCOBACTERIAL diseases ,LYMPHOID tissue ,ECTOPIC tissue ,BACTERIAL diseases ,MUCORMYCOSIS - Abstract
Buruli ulcer (BU), caused by Mycobacterium ulcerans (MU), is the third most important mycobacterial diseases after tuberculosis and leprosy in immunocompetent individuals. Although the mode of transmission remains an enigma, disease incidence has been strongly linked to disturbed environment and wetlands. The blunt of the diseases is recorded in West African countries along the Gulf of Guinea, and children 15 years and below account for about 48% of all cases globally. Prior to 2004, wide surgical excisions and debridement of infected necrotic tissues followed by skin grafting was the accepted definitive treatment of BU. However, introduction of antibiotic therapy, daily oral rifampicin (10 mg/kg) plus intramuscular injection of streptomycin (15 mg/kg), for 8 weeks by the WHO in 2004 has reduced surgery as an adjunct for correction of deformities and improved wound healing. An all‐oral regimen is currently on clinical trial to replace the injectable. It is thought that a protective cloud of the cytotoxic toxin mycolactone kills infiltrating leucocytes leading to local immunosuppression and down‐regulation of the systemic immune system. Our studies of lesions from BU patients treated with SR have demonstrated treatment‐associated initiation of vigorous immune responses and the development of ectopic lymphoid tissue in the BU lesions. Despite these interventions, there are still challenges that bedevil the management of BU including paradoxical reactions, evolution of lesions after therapy, prolong viability of MU in BU lesions, and development of secondary bacterial infection. In this paper, we will mainly focus on the critical and pertinent challenges that undermine BU treatment toward effective control of BU. Review on the critical and pertinent challenges that undermine BU treatment toward effective control of Buruli ulcer. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
38. Sec61 blockade by mycolactone: A central mechanism in Buruli ulcer disease.
- Author
-
Demangel, Caroline and High, Stephen
- Subjects
- *
LACTONES , *BURULI ulcer , *MYCOBACTERIA , *IMMUNOREGULATION , *ENDOPLASMIC reticulum , *BIOCHEMICAL mechanism of action - Abstract
Infection with Mycobacterium ulcerans results in a necrotising skin disease known as a Buruli ulcer, the pathology of which is directly linked to the bacterial production of the toxin mycolactone. Recent studies have identified the protein translocation machinery of the endoplasmic reticulum (ER) membrane as the primary cellular target of mycolactone, and shown that the toxin binds to the core subunit of the Sec61 complex. Mycolactone binding strongly inhibits the capacity of the Sec61 translocon to transport newly synthesised membrane and secretory proteins into and across the ER membrane. Since the ER acts as the entry point for the mammalian secretory pathway, and hence regulates initial access to the entire endomembrane system, mycolactone‐treated cells have a reduced ability to produce a range of proteins including secretory cytokines and plasma membrane receptors. The global effect of this molecular blockade of protein translocation at the ER is that the host is unable to mount an effective immune response to the underlying mycobacterial infection. Prolonged exposure to mycolactone is normally cytotoxic, since it triggers stress responses activating the transcription factor ATF4 and ultimately inducing apoptosis. Review: Buruli ulcer (BU) is a necrotising skin disease caused by infection with Mycobacterium ulcerans. The pathogenesis of BU is closely associated with the bacterial production of a diffusible polyketide‐derived macrolide named mycolactone. Recent work has identified mycolactone as a highly potent, yet selective inhibitor of the Sec61 translocon. This review provides an update of our current understanding of its mechanism of action, and of the contribution of Sec61 blockade to the diverse clinical manifestations of BU. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
39. Total Syntheses of Mycolactone A/B and its Analogues for the Exploration of the Biology of Buruli Ulcer
- Author
-
Sarah Saint-Auret, Anne-Caroline Chany, Virginie Casarotto, Cédric Tresse, Lise Parmentier, Hajer Abdelkafi, and Nicolas Blanchard
- Subjects
Buruli ulcer ,Diverted total synthesis ,Mycolactone ,Total synthesis ,Chemistry ,QD1-999 - Abstract
Buruli ulcer, classified as a neglected tropical disease by the World Health Organization, is caused by a mycobacterium which secretes a macrolidic exotoxin called mycolactone A/B. In this article, several synthetic strategies for the preparation of this toxin are discussed, highlighting the importance of total synthesis for the exploration of biological mechanism underpinning relevant human diseases.
- Published
- 2017
- Full Text
- View/download PDF
40. Transient up-regulation of miR-155-3p by lipopolysaccharide in primary human monocyte-derived macrophages results in RISC incorporation but does not alter TNF expression
- Author
-
Rachel E. Simmonds
- Subjects
0301 basic medicine ,Toll-like receptor signalling ,Microarray ,Cell ,TNF ,Medicine (miscellaneous) ,mycolactone ,General Biochemistry, Genetics and Molecular Biology ,miR-155 ,03 medical and health sciences ,0302 clinical medicine ,Downregulation and upregulation ,microRNA ,medicine ,primary human cells ,Messenger RNA ,Innate immune system ,Chemistry ,monocyte-derived macrophages ,Articles ,Cell biology ,medicine.anatomical_structure ,030104 developmental biology ,030220 oncology & carcinogenesis ,miRNAs ,Tumor necrosis factor alpha ,Research Article - Abstract
Background: The innate immune response is a tightly regulated process that reacts rapidly in response to pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS). Evidence is accumulating that microRNAs contribute to this, although few studies have examined the early events that constitute the “primary” response. Methods: LPS-dependent changes to miRNA expression were studied in primary human monocyte-derived macrophages (1°MDMs). An unbiased screen by microarray was validated by qPCR and a method for the absolute quantitation of miRNAs was also developed, utilising 5’ phosphorylated RNA oligonucleotide templates. RNA immunoprecipitation was performed to explore incorporation of miRNAs into the RNA-induced silencing complex (RISC). The effect of miRNA functional inhibition on TNF expression (mRNA and secretion) was investigated. Results: Of the 197 miRNAs expressed in 1°MDMs, only five were induced >1.5-fold. The most strongly induced was miR-155-3p, the partner strand to miR-155-5p, which are both derived from the MIR155HG/BIC gene (pri-miR-155). The abundance of miR-155-3p was induced transiently ~250-fold at 2-4hrs and then returned towards baseline, mirroring pri-miR-155. Other PAMPs, IL-1β, and TNF caused similar responses. IL-10, NF-κB, and JNK inhibition reduced these responses, unlike cytokine-suppressing mycolactone. Absolute quantitation revealed that miRNA abundance varies widely from donor-to-donor, and showed that miR-155-3p abundance is substantially less than miR-155-5p in unstimulated cells. However, at its peak there were 446-1,113 copies/cell, and miR-155-3p was incorporated into the RISC with an efficiency similar to miR-16-5p and miR-155-5p. Inhibition of neither miRNA affected TNF secretion after 2hrs in 1°MDMs, but technical challenges here are noted. Conclusions: Dynamic regulation of miRNAs during the primary response is rare, with the exception of miR-155-3p. Further work is required to establish whether its low abundance, even at the transient peak, is sufficient for biological activity and to determine whether there are specific mechanisms determining its biogenesis from miR-155 precursors
- Published
- 2022
- Full Text
- View/download PDF
41. Infiltrating leukocytes surround early Buruli ulcer lesions, but are unable to reach the mycolactone producing mycobacteria.
- Author
-
Ruf, Marie-Thérèse, Steffen, Christina, Bolz, Miriam, Schmid, Peter, and Pluschke, Gerd
- Subjects
- *
LEUCOCYTES , *BURULI ulcer , *HISTOPATHOLOGY , *MYCOBACTERIUM , *TISSUE wounds - Published
- 2017
- Full Text
- View/download PDF
42. An Antigen Capture Assay for the Detection of Mycolactone, the Polyketide Toxin of Mycobacterium ulcerans
- Author
-
Louisa Warryn, Karl-Heinz Altmann, Philipp Gersbach, Gerd Pluschke, Matthias Gehringer, and Jean-Pierre Dangy
- Subjects
Buruli ulcer ,medicine.drug_class ,Immunology ,medicine.disease_cause ,Monoclonal antibody ,Epitope ,Microbiology ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,Polyketide ,0302 clinical medicine ,Novel Immunological Methods ,medicine ,Animals ,Immunology and Allergy ,Mycolactone ,Antigens, Bacterial ,Molecular Structure ,Mycobacterium ulcerans ,biology ,Toxin ,Antibodies, Monoclonal ,Antigen capture assay ,medicine.disease ,biology.organism_classification ,chemistry ,Macrolides ,030215 immunology - Abstract
Mycolactone is a cytotoxin responsible for most of the chronic necrotizing pathology of Mycobacterium ulcerans disease (Buruli ulcer). The polyketide toxin consists of a 12-membered lactone ring with a lower O-linked polyunsaturated acyl side chain and an upper C-linked side chain. Mycolactone is unique to M. ulcerans and an immunological Ag capture assay would represent an important tool for the study of Buruli ulcer pathogenesis and for laboratory diagnosis. When testing sets of mycolactone-specific mouse mAbs, we found that Abs against the hydrophobic lower side chain only bind mycolactone immobilized on a solid support but not when present in solution. This observation supports previous findings that mycolactone forms micellar structures in aqueous solution with the hydrophobic region sequestered into the inner core of the aggregates. Although an Ag capture assay typically requires two Abs that recognize nonoverlapping epitopes, our search for matching pairs of mAbs showed that the same mAb could be used both as capture and as detecting reagent for the detection of the mycolactone aggregates. However, the combination of a core-specific and a core/upper side chain–specific mAb constituted the most sensitive ELISA with a sensitivity in the low nanogram range. The results of a pilot experiment showed that the sensitivity of the assay is sufficient to detect mycolactone in swab samples from Buruli ulcer lesions. Although the described capture ELISA can serve as a tool for research on the biology of mycolactone, the assay system will have to be adapted for use as a diagnostic tool.
- Published
- 2021
43. Ketogenic Diet Impairment of Mycobacterium ulcerans Growth and Toxin Production and Enhancement of Host Response to Infection in an Experimental Mouse Model
- Author
-
Mélanie Foulon, Marie Robbe-Saule, Lucille Esnault, Marine Malloci, Anthony Mery, Jean-Paul Saint-André, Anne Croue, Marie Kempf, Chadi Homedan, Estelle Marion, and Laurent Marsollier
- Subjects
0301 basic medicine ,Buruli ulcer ,medicine.medical_treatment ,Disease ,medicine.disease_cause ,Virulence factor ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine ,Animals ,Immunology and Allergy ,Mycolactone ,Buruli Ulcer ,2. Zero hunger ,Wound Healing ,3-Hydroxybutyric Acid ,Mycobacterium ulcerans ,biology ,business.industry ,Toxin ,medicine.disease ,biology.organism_classification ,3. Good health ,Disease Models, Animal ,030104 developmental biology ,Infectious Diseases ,chemistry ,Immunology ,Macrolides ,Diet, Ketogenic ,business ,Wound healing ,030217 neurology & neurosurgery ,Ketogenic diet - Abstract
Ketogenic diets have been used to treat diverse conditions, and there is growing evidence of their benefits for tissue repair and in inflammatory disease treatment. However, their role in infectious diseases has been little studied. Buruli ulcer (Mycobacterium ulcerans infection) is a chronic infectious disease characterized by large skin ulcerations caused by mycolactone, the major virulence factor of the bacillus. In the current study, we investigated the impact of ketogenic diet on this cutaneous disease in an experimental mouse model. This diet prevented ulceration, by modulating bacterial growth and host inflammatory response. β-hydroxybutyrate, the major ketone body produced during ketogenic diet and diffusing in tissues, impeded M. ulcerans growth and mycolactone production in vitro underlying its potential key role in infection. These results pave the way for the development of new patient management strategies involving shorter courses of treatment and improving wound healing, in line with the major objectives of the World Health Organization.
- Published
- 2021
44. Characterization of the Molecular Lipophilicity of Mycolactones A/B and C, Infectious Factors of Mycobacterium ulcerans Agent of Buruli Ulcer
- Author
-
Jean Missa Ehouman, Georges Stéphane Dembélé, Kadjo François Kassi, Nahossé Ziao, Lamoussa Ouattara, and Mamadou Guy-Richard Koné
- Subjects
Buruli ulcer ,chemistry.chemical_compound ,chemistry ,biology ,Mycobacterium ulcerans ,Lipophilicity ,medicine ,General Medicine ,Mycolactone ,medicine.disease ,biology.organism_classification ,Microbiology - Abstract
The work was undertaken as part of the Buruli ulcer control program. It is particularly about the determination of the lipophilicity of mycolactones A/B and C, infectious factors of Mycobacterium ulcerans, the agent of Buruli ulcer. The REKKER method and some free software such as MOLINSPIRATION, ACD/ChemSketch and EPIWED were used for the determination of the lipophilicity of mycolactones A/B and C. Very high logP values were found and respectively ranged from 12.11 to 11.41 for mycolactone A/B and 11.69 to 11.58 for mycolactone C. These values obtained from this coefficient, show that mycolactones A/B and C are naturally lipophilic and that actually reflects their effective presence in the subcutaneous fat of the infected area. These results are very encouraging and promising. They are key factors for a better understanding of the biological activities of the two mycolactones and pave the way for the proposal of a mechanism to annihilate their destructive effects.
- Published
- 2021
45. Could Mycolactone Inspire New Potent Analgesics? Perspectives and Pitfalls
- Author
-
Marie-Line Reynaert, Denis Dupoiron, Edouard Yeramian, Laurent Marsollier, and Priscille Brodin
- Subjects
mycolactone ,analgesia ,neurons ,AT2R ,drug development ,Medicine - Abstract
Pain currently represents the most common symptom for which medical attention is sought by patients. The available treatments have limited effectiveness and significant side-effects. In addition, most often, the duration of analgesia is short. Today, the handling of pain remains a major challenge. One promising alternative for the discovery of novel potent analgesics is to take inspiration from Mother Nature; in this context, the detailed investigation of the intriguing analgesia implemented in Buruli ulcer, an infectious disease caused by the bacterium Mycobacterium ulcerans and characterized by painless ulcerative lesions, seems particularly promising. More precisely, in this disease, the painless skin ulcers are caused by mycolactone, a polyketide lactone exotoxin. In fact, mycolactone exerts a wide range of effects on the host, besides being responsible for analgesia, as it has been shown notably to modulate the immune response or to provoke apoptosis. Several cellular mechanisms and different targets have been proposed to account for the analgesic effect of the toxin, such as nerve degeneration, the inhibition of inflammatory mediators and the activation of angiotensin II receptor 2. In this review, we discuss the current knowledge in the field, highlighting possible controversies. We first discuss the different pain-mimicking experimental models that were used to study the effect of mycolactone. We then detail the different variants of mycolactone that were used in such models. Overall, based on the results and the discussions, we conclude that the development of mycolactone-derived molecules can represent very promising perspectives for new analgesic drugs, which could be effective for specific pain indications.
- Published
- 2019
- Full Text
- View/download PDF
46. Recombinant Antibodies against Mycolactone
- Author
-
Leslie Naranjo, Fortunato Ferrara, Nicolas Blanchard, Caroline Demangel, Sara D’Angelo, M. Frank Erasmus, Andre A. Teixeira, and Andrew R.M. Bradbury
- Subjects
mycolactone ,Buruli ulcer ,recombinant antibody ,phage display ,yeast display ,single chain Fv ,Medicine - Abstract
In the past, it has proved challenging to generate antibodies against mycolactone, the primary lipidic toxin A of Mycobacterium ulcerans causing Buruli ulcer, due to its immunosuppressive properties. Here we show that in vitro display, comprising both phage and yeast display, can be used to select antibodies recognizing mycolactone from a large human naïve phage antibody library. Ten different antibodies were isolated, and hundreds more identified by next generation sequencing. These results indicate the value of in vitro display methods to generate antibodies against difficult antigenic targets such as toxins, which cannot be used for immunization unless inactivated by structural modification. The possibility to easily generate anti-mycolactone antibodies is an exciting prospect for the development of rapid and simple diagnostic/detection methods.
- Published
- 2019
- Full Text
- View/download PDF
47. Understanding the Significance of Biochemistry in the Storage, Handling, Purification, and Sampling of Amphiphilic Mycolactone
- Author
-
Jessica Z. Kubicek-Sutherland, Dung M. Vu, Aaron S. Anderson, Timothy C. Sanchez, Paul J. Converse, Ricardo Martí-Arbona, Eric L. Nuermberger, Basil I. Swanson, and Harshini Mukundan
- Subjects
mycolactone ,storage and handling ,amphiphilic ,lipoproteins ,Medicine - Abstract
Mycolactone, the amphiphilic macrolide toxin secreted by Mycobacterium ulcerans, plays a significant role in the pathology and manifestations of Buruli ulcer (BU). Consequently, it follows that the toxin is a suitable target for the development of diagnostics and therapeutics for this disease. Yet, several challenges have deterred such development. For one, the lipophilic nature of the toxin makes it difficult to handle and store and contributes to variability associated with laboratory experimentation and purification yields. In this manuscript, we have attempted to incorporate our understanding of the lipophilicity of mycolactone in order to define the optimal methods for the storage, handling, and purification of this toxin. We present a systematic correlation of variability associated with measurement techniques (thin-layer chromatography (TLC), mass spectrometry (MS), and UV-Vis spectrometry), storage conditions, choice of solvents, as well as the impact of each of these on toxin function as assessed by cellular cytotoxicity. We also compared natural mycolactone extracted from bacterial culture with synthesized toxins in laboratory (solvents, buffers) and physiologically relevant (serum) matrices. Our results point to the greater stability of mycolactone in organic, as well as detergent-containing, solvents, regardless of the container material (plastic, glass, or silanized tubes). They also highlight the presence of toxin in samples that may be undetectable by any one technique, suggesting that each detection approach captures different configurations of the molecule with varying specificity and sensitivity. Most importantly, our results demonstrate for the very first time that amphiphilic mycolactone associates with host lipoproteins in serum, and that this association will likely impact our ability to study, diagnose, and treat Buruli ulcers in patients.
- Published
- 2019
- Full Text
- View/download PDF
48. Molecular Docking and Dynamics Simulation Studies Predict Munc18b as a Target of Mycolactone: A Plausible Mechanism for Granule Exocytosis Impairment in Buruli Ulcer Pathogenesis
- Author
-
Samuel K. Kwofie, Bismark Dankwa, Kweku S. Enninful, Courage Adobor, Emmanuel Broni, Alfred Ntiamoah, and Michael D. Wilson
- Subjects
Buruli ulcer ,mycolactone ,chaperone proteins ,SNARE proteins ,Munc18b ,Sec61 ,AT2R ,WASP ,molecular docking ,molecular dynamics ,Medicine - Abstract
Ulcers due to infections with Mycobacterium ulcerans are characterized by complete lack of wound healing processes, painless, an underlying bed of host dead cells and undermined edges due to necrosis. Mycolactone, a macrolide produced by the mycobacterium, is believed to be the toxin responsible. Of interest and relevance is the knowledge that Buruli ulcer (BU) patients remember experiencing trauma previously at the site of the ulcers, suggesting an impairment of wound healing processes, the plausible effect due to the toxin. Wound healing processes involve activation of the blood platelets to release the contents of the dense granules mainly serotonin, calcium ions, and ADP/ATP by exocytosis into the bloodstream. The serotonin release results in attracting more platelets and mast cells to the wound site, with the mast cells also undergoing degranulation, releasing compounds into the bloodstream by exocytosis. Recent work has identified interference in the co-translational translocation of many secreted proteins via the endoplasmic reticulum and cell death involving Wiskott-Aldrich syndrome protein (WASP), Sec61, and angiotensin II receptors (AT2R). We hypothesized that mycolactone by being lipophilic, passively crosses cell membranes and binds to key proteins that are involved in exocytosis by platelets and mast cells, thus inhibiting the initiation of wound healing processes. Based on this, molecular docking studies were performed with mycolactone against key soluble n-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and regulators, namely Vesicle-associated membrane protein (VAMP8), Synaptosomal-associated protein (SNAP23, syntaxin 11, Munc13-4 (its isoform Munc13-1 was used), and Munc18b; and also against known mycolactone targets (Sec61, AT2R, and WASP). Munc18b was shown to be a plausible mycolactone target after the molecular docking studies with binding affinity of −8.5 kcal/mol. Structural studies and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding energy calculations of the mycolactone and Munc18b complex was done with 100 ns molecular dynamics simulations using GROMACS. Mycolactone binds strongly to Munc18b with an average binding energy of −247.571 ± 37.471 kJ/mol, and its presence elicits changes in the structural conformation of the protein. Analysis of the binding interactions also shows that mycolactone interacts with Arg405, which is an important residue of Munc18b, whose mutation could result in impaired granule exocytosis. These findings consolidate the possibility that Munc18b could be a target of mycolactone. The implication of the interaction can be experimentally evaluated to further understand its role in granule exocytosis impairment in Buruli ulcer.
- Published
- 2019
- Full Text
- View/download PDF
49. Impact of mycolactone produced by Mycobacterium ulcerans on life-history traits of Aedes aegypti (L.) and resulting habitat selection for oviposition
- Author
-
L T Crippen, Jeffery K. Tomberlin, A M Mashlawi, and Heather R. Jordan
- Subjects
Buruli ulcer ,Larva ,Mycobacterium ulcerans ,biology ,Transmission (medicine) ,Oviposition ,fungi ,Zoology ,Tropical disease ,Aedes aegypti ,biology.organism_classification ,medicine.disease ,Life history theory ,chemistry.chemical_compound ,chemistry ,Aedes ,parasitic diseases ,medicine ,Animals ,Female ,Macrolides ,Mycolactone ,Ecosystem - Abstract
Buruli ulcer (BU) is a globally recognized, yet largely neglected tropical disease whose etiologic agent is Mycobacterium ulcerans. Although the exact mode of transmission is unclear, epidemiological evidence links BU incidence with slow-moving or stagnant, aquatic habitats, and laboratory-based experiments have shown disease manifestation in animals with dermal punctures. Therefore, hypotheses for transmission include contact with slowmoving aquatic habitats and associated biting aquatic insects, such as mosquitoes. Recent research demonstrated the toxin produced by M. ulcerans, mycolactone, is an attractant for adult mosquitoes seeking a blood-meal as well as oviposition sites. In the study presented here, we examined the impact of mycolactone at different concentrations on immature lifehistory traits of Aedes aegypti, which commonly occurs in the same environment as M. ulcerans. We determined percent egg hatch was not significantly different across treatments. However, concentration impacted the survivorship of larval mosquitoes to the adult stage (p0.001). Resulting adults also showed a slight preference, but not significant (p0.05), for oviposition in habitats contaminated with mycolactone suggesting a legacy effect.
- Published
- 2020
50. Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export.
- Author
-
Grotzke, Jeff E., Cresswell, Peter, Kozik, Patrycja, Amigorena, Sebastian, Morel, Jean-David, Demangel, Caroline, Impens, Francis, and Pietrosemoli, Natalia
- Subjects
- *
ENDOPLASMIC reticulum , *MEMBRANE proteins , *DENDRITIC cells , *CYTOSOL , *ANTIGENS - Abstract
Although antigen cross-presentation in dendritic cells (DCs) is critical to the initiation of most cytotoxic immune responses, the intracellular mechanisms and traffic pathways involved are still unclear. One of the most critical steps in this process, the export of internalized antigen to the cytosol, has been suggested to be mediated by Sec61. Sec61 is the channel that translocates signal peptide-bearing nascent polypeptides into the endoplasmic reticulum (ER), and it was also proposed to mediate protein retrotranslocation during ER-associated degradation (a process called ERAD). Here, we used a newly identified Sec61 blocker, mycolactone, to analyze Sec61's contribution to antigen cross-presentation, ERAD, and transport of internalized antigens into the cytosol. As shown previously in other cell types, mycolactone prevented protein import into the ER of DCs. Mycolactone-mediated Sec61 blockade also potently suppressed both antigen cross-presentation and direct presentation of synthetic peptides to CD8+ T cells. In contrast, it did not affect protein export from the ER lumen or from endosomes into the cytosol, suggesting that the inhibition of cross-presentation was not related to either of these trafficking pathways. Proteomic profiling of mycolactoneexposed DCs showed that expression of mediators of antigen presentation, including MHC class I and β2 microglobulin, were highly susceptible to mycolactone treatment, indicating that Sec61 blockade affects antigen cross-presentation indirectly. Together, our data suggest that the defective translocation and subsequent degradation of Sec61 substrates is the cause of altered antigen cross-presentation in Sec61-blocked DCs. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
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