Project description:Mycolactone, a lipid-like toxin, is the major virulence factor of Mycobacterium ulcerans, the etiological agent of Buruli ulcer. Its involvement in lesions development has been widely described in early stages of the disease, through its cytotoxic and immunosuppressive activities, but less is known about later stages. Here, we revisit the role of mycolactone in disease outcome and provide the first demonstration of the pro-inflammatory potential of this toxin. We found that the mycolactone-containing mycobacterial extracellular vesicles produced by M. ulcerans induced the production of IL-1β, a potent pro-inflammatory cytokine, in a TLR2-dependent manner, targeting NLRP3/1 inflammasomes. We showed our data to be relevant in a physiological context. The in vivo injection of these mycolactone-containing vesicles induced a strong local inflammatory response and tissue damages, which were prevented by corticosteroids. Finally, several soluble pro-inflammatory factors, including IL-1β, were detected in infected tissues from mice and Buruli ulcer patients. Our results revisit Buruli ulcer pathophysiology by giving a new insight, thus paving the way for development of new therapeutic strategies, taking account the pro-inflammatory potential of mycolactone.
Project description: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, suggesting that M. ulcerans switches to low levels of mycolactone production, adapting its strategy to survive in such a hostile environment. We investigated the regulation of mycolactone production, by using an RNA-seq strategy to study bacterial adaptation within our original mouse model of spontaneous healing. 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 and changes in cell wall composition. These findings shed new light on mycolactone regulation and pave the way for new therapeutic strategies.
2021-05-17 | GSE157956 | GEO
Project description:PPE barcoding the Buruli ulcer agent, Mycobacterium ulcerans
Project description:Buruli ulcer (BU) is a tropical infectious disease caused by Mycobacterium ulcerans. BU causes profound skin ulcerations and eventually bone infections. Life-long functional sequelae are observed in more than 20% of patients, most of whom are children. Several observations, in particular the large variability in the clinical severity of the disease after infection, suggested the role of human genetic factors in the development of BU. Here, we report two children with severe BU, born of consanguineous parents. The deep genetic exploration of this family led to the identification of a small deletion on chromosome 8 in both patients. The corresponding article is in press in PloS Neglected Tropical Diseases
2018-04-23 | GSE113496 | GEO
Project description:Comparative genomics reveals diversity and spatial clustering of Mycobacterium ulcerans in a small Buruli ulcer endemic area of West-Africa
Project description:Mycolactone is a diffusible macrolide produced by the skin pathogen Mycobacterium ulcerans that suppresses the development of protective immunity against Buruli ulcer disease. In this proteomics study we aimed to identify proteins of which the expression levels changed upon mycolactone treatment. Jurkat T cells were labeled light or heavy by stable isotope labeling by amino acids in cell culture (SILAC), then treated with mycolactone (light) or vehicle (heavy) for 1h prior to activation with PMA/IO for 6h. After mixing light- and heavy-labeled cultures, cells were lysed and extracted proteins were digested with trypsin. The resulting peptide mixture was analyzed by LC-MS/MS and proteins were identified by the MaxQuant software and quantified based on the intensity of the light and heavy signals in the MS spectra of their peptides. The analysis was repeated with reversed labeling, leading to a total of 4,636 proteins that were quantified in both analyses. Interestingly, 52 proteins were down-regulated in mycolactone-treated cells (mycolactone/control ratio < 1.4), while only two proteins were up-regulated (mycolactone/control ratio > 1.4). Gene ontology analysis further revealed that the down-regulated proteins were significantly enriched in proteins located in the plasma membrane and endoplasmic reticulum and we could show that this enrichment was not due to a bias in protein extraction, since the distribution of all identified proteins across different subcellular compartments was similar to those of all human proteins. Analysis of SP-PIR Family-Domains keywords in the UniProt database confirmed this observation and showed an additional enrichment in glycoproteins, proteins with an immunoglobulin domain and proteins involved in immune responses. Furthermore, we observed that the down-regulated proteins were significantly enriched in single-pass type I/II membrane proteins. In contrast, the fraction of multi-pass membrane proteins was comparable among the down-regulated and all identified proteins, suggesting that multi-pass membrane proteins may at least partially resist mycolactone-mediated down-regulation.