Project description:Mycobacterium abscessus is nowadays under the spotlight of the scientific community. This pathogenic mycobacteria is indeed responsible for a wide spectrum of infections involving mostly pulmonary infections in patients with cystic fibrosis. M. abscessus is intrinsically resistant to a broad range of antibiotics, including most antitubercular drugs, and is considered the most pathogenic and chemotherapy-resistant rapidly growing mycobacterium. Consequently, with very limited treatment options, the development of new therapeutic approaches to fight this pathogen are urgently needed. In this context, 19 oxadiazolone (OX) derivatives have been investigated for their antibacterial activity against both the rough (R) and smooth (S) variants of M. abscessus. Several OXs were active against extracellular M. abscessus growth with moderated minimal inhibitory concentrations (MIC), or intracellularly by inhibiting M. abscessus growth inside infected macrophages with MIC values similar to those of imipenem. Such promising results prompted us to identify the potential target enzymes of the sole extra and intracellular inhibitor of M. abscessus growth, i.e., iBpPPOX via activity-based protein profiling combined with mass spectrometry. This approach led to the identification of 21 potential protein candidates being mostly involved in M. abscessus lipid metabolism and/or in cell wall biosynthesis.
Project description:Mycobacterium abscessus (Mabs) is a fast-growing, non-tuberculous mycobacterium responsible for serious lung infections in patients with cystic fibrosis. This bacterium evolves during the pulmonary infection between a smooth (S) and a rough morphotype (R). We have previously isolated the lsr2 gene as being differentially expressed during the transition between Mabs-S and Mabs-R. lsr2 encodes a pleiotropic transcription factor belonging to the superfamily of nucleoid-associated proteins (NAPs), which play an essential role in the hierarchical organization of bacterial chromosomes. The present study aims to unravel the molecular role of Lsr2 in regulating expression of gene involved in the adaptation and the pathobiology of Mabs using both RNA-Seq and ChIP-seq.
Project description:Mycobacterium abscessus (Mabs) is a fast-growing, non-tuberculous mycobacterium responsible for serious lung infections in patients with cystic fibrosis. This bacterium evolves during the pulmonary infection between a smooth (S) and a rough morphotype (R). We have previously isolated the lsr2 gene as being differentially expressed during the transition between Mabs-S and Mabs-R. lsr2 encodes a pleiotropic transcription factor belonging to the superfamily of nucleoid-associated proteins (NAPs), which play an essential role in the hierarchical organization of bacterial chromosomes. The present study aims to unravel the molecular role of Lsr2 in regulating expression of gene involved in the adaptation and the pathobiology of Mabs using both RNA-Seq and ChIP-seq.
Project description:Mycobacterium abscessus is nowadays under the spotlight of the scientific community. This pathogenic mycobacteria is indeed responsible for a wide spectrum of infections involving mostly pulmonary infections in patients with cystic fibrosis. M. abscessus is intrinsically resistant to a broad range of antibiotics, including most antitubercular drugs, and is considered the most pathogenic and chemotherapy-resistant rapidly growing mycobacterium. Consequently, with very limited treatment options, the development of new therapeutic approaches to fight this pathogen are urgently needed. 38 new analogs of Cyclipostins & Cyclophostin (CyC), compounds naturally produced by Streptomyces species, have been synthesized. Their antibacterial activities against clinical isolates belonging to the M. chelonae-abscessus clade, as well as Gram-negative and Gram-positive bacteria have been evaluated by the REMA method. The intracellular activities of the CyC against intramacrophagic M. abscessus have also been investigated and compared to those of imipenem. The CyCs displayed very low toxicity towards host cells and their inhibitory activity was exclusively restricted to mycobacteria. The best candidate, CyC17, showed a high selectivity for mycobacteria with MIC values (<2 up to 40 µg/mL) comparable to those of most classical antibiotics used to treat M. abscessus infections. Of importance, several CyCs were active against extracellular M. abscessus growth (i.e., CyC17 / CyC18β / CyC25 / CyC26) or against intracellular mycobacteria inside macrophages (i.e., CyC7α,β / CyC8α,β) with MIC values similar to or better than those of standard antibiotics. Based on these results, we intended to identify the potential target enzymes of CyC17/CyC26 in M. abscessus by activity-based protein profiling (ABPP) approach coupled with mass spectrometry differential analysis.
Project description:Mycobacterium abscessus [M. abscessus (sensu lato) or M. abscessus group] comprises three closely related taxa with taxonomic status under revision: M. abscessus sensu stricto, M. bolletii and M. massiliense. We describe here a simple, robust and cost effective PCR-based method for distinguishing among M. abscessus, M. massiliense and bolletii. Based on the M. abscessus ATCC 19977T genome, discriminatory regions were identified between M. abscessus and M. massiliense from array-based comparative genomic hybridization. A typing scheme using PCR primers designed for four of these locations was applied to 46 well-characterized clinical isolates comprising 29 M. abscessus, 15 M. massiliense and 2 M. bolletii previously identified by multi-target sequencing. Interestingly, 2 isolates unequivocally identified as M. massiliense were shown to have a full length erm(41) instead of the expected gene deletion and showed inducible clarithromycin resistance after 14 days. We propose using this PCR-based typing scheme combined with erm(41) PCR for a straightforward identification of M. abscessus, M. massiliense and M. bolletii and assessment of inducible clarithromycin resistance. This method can be easily implemented into a routine workflow providing subspecies level identification within 24 hours of isolation of M. abscessus group. Two-color CGH with 4 independent Mycobacterium clinical isolates and the M massiliense type strain (CCUG 48898) labeled with Cy3 were cohybridized with the M abscessus type strain (ATCC 19977) labeled with Cy5 on a tiling array designed against the M abscessus type strain
Project description:Human macrophages are a natural host of many mycobacterium species, including Mycobacterium abscessus (M. abscessus), an emerging pathogen affecting patients with lung diseases and immunocompromised individuals. There are few available treatments and the search for effective antibiotics against M. abscessus has been hindered by the lack of a tractable in vitro intracellular model of infection. Here, we established a reliable model for M. abscessus infection using human pluripotent stem cell-derived macrophages (hPSC-macrophages). hPSC differentiation permitted a reproducible generation of functional human macrophages that were highly susceptible to M. abscessus infection. Electron microscopy demonstrated that M. abscessus was present in the vacuoles of hPSC-macrophages. RNA-sequencing analysis revealed a time dependent host cell response to M. abscessus, with differing gene and protein expression patterns observed at 3-hours, 24-hours and 48-hours post-infection. Culture of engineered tdTOMATO-expressing hPSC-macrophages with GFP-expressing M. abscessus enabled rapid and image-based high-throughput analysis of intracellular infection and quantitative assessment of antibiotic resistance and efficacy. Our study describes the first hPSC-based model for M. abscessus infection, which represents a novel platform for studying M. abscessus-host interaction and an accessible tool for drug discovery.
Project description:Mycobacterium abscessus is an emerging pathogen causing pulmonary infections in those with inflammatory lung disorders, such as Cystic Fibrosis (CF), and is associated with the highest fatality rate among rapidly growing mycobacteria (RGM). Phenotypically, MAB manifests as either a Smooth (MAB-S) or a Rough (MAB-R) morphotype, which differ in their levels of cell wall glycopeptidolipids (GPLs) and in their pathogenicity in vivo. As one of the primary immune cells encountered by MAB, we sought to examine the early transcriptional events within macrophages, following infection with both MAB-S or MAB-R. We sampled the small RNA (sRNA) transcriptome of THP-1-derived macrophages infected with both MAB-R and MAB-S at 1, 4 and 24 hours post-infection (hpi) using RNA-seq. MAB-S elicited a more robust transcriptional response at the miRNA level, reflecting higher cytokine levels in culture supernatants. However, and a direct comparison identified no differentially expressed miRNAs between MAB-R- and MAB-S-infected cells. Most of the induced miRNAs have previously been associated with mycobacterial infection and overall miRNA expression patterns were similarly highly correlated between the morphotypes. THP-1-derived macrophages were infected in parallel with the MAB-R and MAB-S morphotypes. Poly-A selected RNAs were purified and sequenced at 1, 4 and 24 hours post-infection, and compared with uninfected controls.
Project description:RNA sequencing (RNA-seq) of Mycobacterium abscessus in four infection-relevant culture conditions: hypoxic stress, artificial sputum medium, kanamycin-treated medium, and erythromycin-treated medium. Triplicate cultures of M. abscessus were grown in (1) Artificial Sputum media, (2) hypoxic conditions, (3) the presence of kanamycin, and (4) the presence of erythromycin. Triplicate controls were prepared for sample (1) and samples (2-4).