Project description:Identification of molecular key determinants of the Mycobacterium abscessus smooth and rough morphotypes through transcriptome analyses
Project description:The response of human neutrophils to the emerging pathogen Mycobacterium abscessus has not been described. However, M. abscessus infections are frequently associated with neutrophil-rich abscesses. To better understand the reponse of neutrophils to M. abscessus we performed gene expression analysis using Affymetrix HG-U133A Plus 2.0 microarrays. Human neutrophils from healthy donors were stimulated with isogenic rough and smooth morphotypes of M. abscessus. Staphylococcus aureus was used as a control. Gene expression was compared to neutrophils left unstimulated. Neutrophils from four individual donors were isolated on separate days and stimulated with freshly prepared bacteria. Neutrophils (stimulated and control) were left for 2 hours before total RNA was isolated, and biotinylated cRNA was prepared by standard methods. Analysis indicates that M. abscessus morphotypes induce a limited number of genes, when compared to S. aureus, which are enriched in genes for cytokines and chemokines, including neutrophil-specific chemokines. These data suggest that neutrophils have a limited response to M. abscessus, which may contribute to neutrophil-rich abscess formation.!Series_overall_design = Human neutrophils from healthy donors were exposed to rough Mab (ATCC 19977T), smooth Mab (ATCC 19977T) and S. aureus (CF clinical strain) for two hours; control cells were exposed to saline.
Project description:We used microarrays to describe the gene expression in response to two isogenic morphotypes of M. abscessus (Mab) and to Staphylococcus aureus. Human neutrophils from healthy donors were exposed to rough Mab (ATCC 19977T), smooth Mab (ATCC 19977T) and S. aureus (CF clinical strain) for two hours; control cells were exposed to saline.
Project description:In this study, we were interested to get deeper insights into the molecular mechanisms that govern the formation and selection of the different colony morphologies in Mycobacterium abscessus strains, including the potential reversibility of the rough (R) phenotype into a smooth (S) phenotype. We used next generation sequencing (NGS) and micro-array / RNAseq approaches to determine the genome sequences and transcriptomic profiles of three isogenic S/R strain couples of M. abscessus. One clinical isolate strain named CF and two collection strains referred as 19977-AT and 19977-IP. To perform the transcriptomic comparison of the rough variant versus the smooth variant for each M. abscessus strain, a customized micro-array has been manufactured by Agilent (8 x 15k format). The design of oligonucleotides covering all protein coding sequences was done using OligoArray version 2.1 on the basis of the 4920 predicted coding sequences composing the entire M. abscessus genome. The experimental data for each of the 3 strains consisted of 6 hybridizations (3 biological replicates with dye-swap).
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:Members of the Mycobacterium (M.) abscessus complex (MABC) are rapidly growing mycobacteria showing smooth and/or rough colony morphotype. While not as virulent as M. tuberculosis, they can cause soft tissue infection and fatal pulmonary disease, especially in patients with cystic fibrosis. Diagnosing MABC pulmonary disease is challenging since the isolation of M. abscessus from respiratory samples is in itself not diagnostic and the clinical features are often non-specific. Immunologic assays, which could aid in the understanding and diagnosis of the disease, are not available. In this study eight rough and six smooth colony morphotype isolates were collected from seven clinical MABC strains and the M. abscessus reference strain ATCC19977, as six strains showed both morphotypes simultaneously and two strains only showed a rough morphotype. Clinical isolates were submitted to whole genome sequencing. Quantitative proteomic analysis was performed on bacterial lysates and the culture supernatant of all 14 isolates. Supernatant proteins present in all isolates were compared in a BLAST search against other clinically significant mycobacterial species to determine species-specific proteins of MABC. In silico B- and T-cell epitope prediction was performed for species-specific proteins. All clinical strains were found to be M. abscessus ssp. abscessus. Six of seven rough colony clinical isolates contained genetic changes in the MAB_4099c gene, which is a likely genetic basis for the rough morphotype. Proteomic analysis detected 3 137 different proteins in total of which 79 proteins were found in the culture supernatants of all isolates. BLAST analyses of these 79 proteins identified 12 of those exclusively encoded by all members of MABC plus M. immunogenum. In silico prediction of epitopes predicted B- and T-cell epitopes in all these 12 species-specific proteins, rendering them promising candidates for future studies on immune pathogenesis and immune diagnostic tools for MABC disease.
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. Size-selected small RNAs were purified and sequenced at 1, 4 and 24 hours post-infection, and compared with uninfected controls.
Project description:In this study, we were interested to get deeper insights into the molecular mechanisms that govern the formation and selection of the different colony morphologies in Mycobacterium abscessus strains, including the potential reversibility of the rough (R) phenotype into a smooth (S) phenotype. We used next generation sequencing (NGS) and micro-array / RNAseq approaches to determine the genome sequences and transcriptomic profiles of three isogenic S/R strain couples of M. abscessus. One clinical isolate strain named CF and two collection strains referred as 19977-AT and 19977-IP.
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.