Dataset Information

Kinetics of mycolactone in human subcutaneous tissue during antibiotic therapy for Mycobacterium ulcerans disease.

ABSTRACT:

Background

Mycobacterium ulcerans (M. ulcerans) causes a devastating necrotising infection of skin tissue leading to progressive ulceration. M. ulcerans is the only human pathogen that secretes mycolactone, a polyketide molecule with potent cytotoxic and immunomodulatory properties. These unique features make mycolactone an attractive biomarker for M. ulcerans disease. We sought to measure the concentration of mycolactone within lesions of patients with Buruli ulcer before, during and after antibiotic treatment to evaluate its association with the clinical and bacteriological response to therapy.

Methods

Biopsies of M. ulcerans infected skin lesions were obtained from patients before, during and after antibiotic therapy. Lipids were extracted from the biopsies and concentration of mycolactone was assayed by mass spectrometry and a cytotoxicity assay and correlated with clinical and bacteriological response to therapy.

Results

Baseline concentration of mycolactone measured by mass spectrometry predicted time to complete healing of small nodules and ulcers. Even though intra-lesional concentrations of mycolactone declined with antibiotic treatment, the toxin was still present after antibiotic treatment for 6 weeks and also 4 weeks after the end of treatment for 8 weeks in a subgroup of patients with slowly healing lesions. Additionally viable bacilli were detected in a proportion of these slowly healing lesions during and after treatment.

Conclusions

Our findings indicate that baseline intra-lesional mycolactone concentration and its kinetics with antibiotic therapy are important prognostic determinants of clinical and bacteriological response to antibiotic treatment for Mycobacterium ulcerans disease. Mycolactone may be a useful biomarker with potential utility in optimising antibiotic therapy.

SUBMITTER: Sarfo FS

PROVIDER: S-EPMC4021496 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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Publications

Kinetics of mycolactone in human subcutaneous tissue during antibiotic therapy for Mycobacterium ulcerans disease.

Sarfo Fred S FS Phillips Richard O RO Zhang Jihui J Abass Mohammed K MK Abotsi Justice J Amoako Yaw A YA Adu-Sarkodie Yaw Y Robinson Clive C Wansbrough-Jones Mark H MH

BMC infectious diseases 20140415

<h4>Background</h4>Mycobacterium ulcerans (M. ulcerans) causes a devastating necrotising infection of skin tissue leading to progressive ulceration. M. ulcerans is the only human pathogen that secretes mycolactone, a polyketide molecule with potent cytotoxic and immunomodulatory properties. These unique features make mycolactone an attractive biomarker for M. ulcerans disease. We sought to measure the concentration of mycolactone within lesions of patients with Buruli ulcer before, during and af ...[more]

PMID: 24731247

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Project description:Diagnosis of the neglected tropical disease, Buruli ulcer, can be made by acid-fast smear microscopy, specimen culture on mycobacterial growth media, polymerase chain reaction (PCR), and/or histopathology. All have drawbacks, including non-specificity and requirements for prolonged culture at 32°C, relatively sophisticated laboratory facilities, and expertise, respectively. The causative organism, Mycobacterium ulcerans, produces a unique toxin, mycolactone A/B (ML) that can be detected by thin layer chromatography (TLC) or mass spectrometric analysis. Detection by the latter technique requires sophisticated facilities. TLC is relatively simple but can be complicated by the presence of other lipids in the specimen. A method using a boronate-assisted fluorogenic chemosensor in TLC can overcome this challenge by selectively detecting ML when visualized with UV light. This report describes modifications in the fluorescent TLC (F-TLC) procedure and its application to the mouse footpad model of M. ulcerans disease to determine the kinetics of mycolactone production and its correlation with footpad swelling and the number of colony forming units in the footpad. The response of all three parameters to treatment with the current standard regimen of rifampin (RIF) and streptomycin (STR) or a proposed oral regimen of RIF and clarithromycin (CLR) was also assessed. ML was detectable before the onset of footpad swelling when there were <10(5) CFU per footpad. Swelling occurred when there were >10(5) CFU per footpad. Mycolactone concentrations increased as swelling increased whereas CFU levels reached a plateau. Treatment with either RIF+STR or RIF+CLR resulted in comparable reductions of mycolactone, footpad swelling, and CFU burden. Storage in absolute ethanol appears critical to successful detection of ML in footpads and would be practical for storage of clinical samples. F-TLC may offer a new tool for confirmation of suspected clinical lesions and be more specific than smear microscopy, much faster than culture, and simpler than PCR.

Project description:Mycolactone is the exotoxin produced by Mycobacterium ulcerans and is the virulence factor behind the neglected tropical disease Buruli ulcer. The toxin has a broad spectrum of biological effects within the host organism, stemming from its interaction with at least two molecular targets and the inhibition of protein uptake into the endoplasmic reticulum. Although it has been shown that the toxin can passively permeate into host cells, it is clearly lipophilic. Association with lipid carriers would have substantial implications for the toxin's distribution within a host organism, delivery to cellular targets, diagnostic susceptibility, and mechanisms of pathogenicity. Yet the toxin's interactions with, and distribution in, lipids are unknown. Herein we have used coarse-grained molecular dynamics simulations, guided by all-atom simulations, to study the interaction of mycolactone with pure and mixed lipid membranes. Using established techniques, we calculated the toxin's preferential localization, membrane translocation, and impact on membrane physical and dynamical properties. The computed water-octanol partition coefficient indicates that mycolactone prefers to be in an organic phase rather than in an aqueous environment. Our results show that in a solvated membrane environment the exotoxin mainly localizes in the water-membrane interface, with a preference for the glycerol moiety of lipids, consistent with the reported studies that found it in lipid extracts of the cell. The calculated association constant to the model membrane is similar to the reported association constant for Wiskott-Aldrich syndrome protein. Mycolactone is shown to modify the physical properties of membranes, lowering the transition temperature, compressibility modulus, and critical line tension at which pores can be stabilized. It also shows a tendency to behave as a linactant, a molecule that localizes at the boundary between different fluid lipid domains in membranes and promotes inter-mixing of domains. This property has implications for the toxin's cellular access, T-cell immunosuppression, and therapeutic potential.

Dataset Information

Kinetics of mycolactone in human subcutaneous tissue during antibiotic therapy for Mycobacterium ulcerans disease.

Background

Methods

Results

Conclusions

Publications

Kinetics of mycolactone in human subcutaneous tissue during antibiotic therapy for Mycobacterium ulcerans disease.

Similar Datasets

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