Biology subjects

Cosson, P.

Publications and source records attributed to Cosson, P..

6 recordsLinked to original sources

bioRxiv2026

Time-resolved transcriptomic profiling of Dictyostelium discoideum infection with Mycobacterium marinum reveals Atg9-dependent restriction via maintenance of vacuole integrity

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a major global health challenge, highlighting the need to better understand host mechanisms restricting mycobacteria infection. Mycobacterium marinum (Mm) shares key virulence mechanisms with Mtb and provides a suitable model for studying mycobacterial pathogenesis. Here, we used Dictyostelium discoideum (Dd), a genetically tractable phagocytic model with evolutionarily conserved pathways shared with mammalian macrophages, to investigate host responses to Mm infection. Time-resolved transcriptomic profiling across early, intermediate, and late stages of infection identified global infection-responsive genes, stage-specific pathways, and substantial conservation with transcriptional responses of human macrophages infected with Mtb. Autophagy and ESCRT pathways were dynamically regulated throughout infection, suggesting stage-specific roles in host defence. We focused on Atg9, an autophagy factor that was strongly induced during infection and recruited to damaged mycobacterium-containing vacuoles (MCVs). Atg9 promoted membrane damage control and maintained MCV integrity, thereby preventing premature bacteria escape to the cytosol of virulent Mm. Loss of Atg9 led to accumulation of MCV damage, accelerated escape to the cytosol, and enhanced intracellular bacteria growth, phenocopying atg1-deficient cells. Our findings further distinguish complementary host defence mechanisms acting at distinct stages of infection: Atg9-associated membrane repair, potentially involving ATG8ylation, limits vacuole damage and bacteria escape during early infection, whereas Atg9-dependent xenophagic restriction contributes to bacteria clearance at later stages. Together, these findings establish Dd as a powerful model for dissecting conserved host responses to mycobacteria and identify Atg9-dependent membrane protection as a key host resistance mechanism with potential relevance to TB pathogenesis and therapeutic intervention.

microbiology↗

bioRxiv2024

Antibacterial effectors in Dictyostelium discoideum: specific activity against different bacterial species

Dictyostelium discoideum is a phagocytic amoeba continuously eating, killing and digesting bacteria. Previous studies have detected in D. discoideum cell extracts a bacteriolytic activity effective against Klebsiella pneumoniae bacteria. In this study we characterized bacteriolytic activities found in D. discoideum cell extracts against five different bacteria (K. pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis). We first analyzed the bacteriolytic activity against these five bacteria in parallel over a range of pH values. We then measured the remaining bacteriolytic activity in D. discoideum kil1 and modA KO mutants. We also performed partial fractionation of D. discoideum extracts and assessed activity against different bacteria. Together our results indicate that optimal bacteriolytic activity against different bacteria results from the action of different effectors. Proteomic analysis allowed us to propose a list of potential bacteriolytic effectors. IMPORTANCEMany antibacterial effectors have been characterized over the last decades, and their biological importance, mode of action and specificity is often still under study. Here we characterized in vitro bacteriolytic activity in D. discoideum extracts against five species of gram-negative and gram-positive bacteria. Our results reveal that optimal lysis of different bacteria mobilizes different effectors. Proteomic analysis generated a list of potential bacteriolytic effectors. This work opens the way for future analysis of the role of individual effectors in living D. discoideum cells.

cell biology↗

bioRxiv2023

PTPRZ1-targeting RNA CAR-T cells exert antigen-specific and bystander antitumor activity in glioblastoma

The great success of chimeric antigen receptor (CAR)-T cell therapy in B-cell malignancies has prompted its translation to solid tumors. In the case of glioblastoma (GBM), clinical trials have shown modest efficacy, but anti-GBM CAR-T cells are being intensely developed. In this study, we selected PTPRZ1 as an attractive new target for GBM treatment. We isolated six anti-human PTPRZ1 scFv from a human phage display library and produced 2nd generation CAR-T cells in an RNA format. Patient-derived GBM PTPRZ1-knock-in cell lines were used to select the CAR construct (471_28z), which showed high cytotoxicity while consistently displaying high CAR expression. CAR-T cells incorporating 471_28z were able to release IFN-{gamma}, IL-2, TNF-, Granzyme B, IL-17A, IL-6, and soluble FasL, and displayed low tonic signaling. Additionally, they maintained an effector memory phenotype after in vitro killing. Importantly, 471_28z CAR-T cells displayed strong bystander killing against PTPRZ1-negative cell lines after pre-activation by PTPRZ1-positive tumor cells, but did not kill antigen-negative non-tumor cells. In an orthotopic xenograft tumor model using NSG mice, a single dose of anti-PTPRZ1 CAR-T cells significantly delayed tumor growth. Taken together, these results validate the use of PTPRZ1 as a new GBM target and prompt the use of anti-PTPRZ1 CAR-T cells for clinical translation.

immunology↗

bioRxiv2020

Metabolic profile discriminates and predicts Arabidopsis susceptibility to virus under field conditions

As obligatory parasites, plant viruses alter host cellular metabolism. There is a lack of information on the variability of virus-induced metabolic responses among genetically diverse plants in a natural context with daily changing conditions. To decipher the metabolic landscape of plant-virus interactions in a natural setting, one hundred and thirty-two and twenty-six accessions of Arabidopsis thaliana were inoculated with Turnip mosaic virus (TuMV), in two field experiments over 2 years. The accessions were phenotyped for viral accumulation, above-ground biomass, targeted and untargeted metabolic profiles. The accessions revealed quantitative response to the virus, from susceptibility to resistance. Susceptible accessions accumulate primary and secondary metabolites upon infection, at the cost of hindered growth. Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) revealed that the primary metabolites sucrose, glucose and glutamate discriminate susceptible and resistant accessions. Twenty-one metabolic signatures were found to significantly accumulate in resistant accessions whereas they maintained their growth at the same level as mock-inoculated plants without biomass penalty. Metabolic content was demonstrated to discriminate and to be highly predictive of the susceptibility of inoculated Arabidopsis. The PLS coefficient estimated in the training data set reveals, after cross-validation, a correlation of 0.61 between predicted and true viral accumulation. This study is the first to describe the metabolic landscape of plant-virus interactions in a natural setting and its predictive link to susceptibility. It reveals that, in this undomesticated species and in ecologically realistic conditions, growth and resistance are in a permanent conversation and provides new insights on plant-virus interactions.

plant biology↗

bioRxiv2019

Time-resolved RNA-seq profiling of the infection of Dictyostelium discoideum by Mycobacterium marinum reveals an integrated host response to damage and stress

Tuberculosis remains the most pervasive infectious disease and the recent emergence of multiple drug-resistant strains emphasizes the need for more efficient drug treatments. The experimentally versatile Dictyostelium discoideum - Mycobacterium marinum infection model provides a powerful system to study mycobacteria pathogenicity and host response. In this study, a time-resolved transcriptomic analysis of the amoeba D. discoideum was performed to decipher the different host pathways impacted during infection. We investigated how D. discoideum fine-tunes its gene expression in response to M. marinum infection by assessing the transcriptomic profile covering the critical stages of entry, establishment of a permissive niche, proliferation and dissemination (1, 3, 6, 12, 24 and 48 hours post infection). Differential gene expression provided a fingerprint of the transcriptome of the host cell in the presence of mycobacteria, and helped identify specific markers and molecular signatures of infection. Enrichment pathway analysis showed that most of the Biological Processes (BP) of upregulated genes at early time point of infection hinted towards damage response and cellular defence, especially in specific pathways involved in membrane repair (ESCRT) and bacteria elimination (autophagy). Whereas at late time points of infection, BP related to starvation were upregulated. Some other signatures were more unexpected, such as cell cycle (downregulation of cytosolic large & small ribosomal subunits) and upregulation of metabolic adaptations (lipids transport).

systems biology↗

bioRxiv2018

Identification of novel anti-bacterial compounds from a chemically highly diverse pathways-based library using phenotypic screens in amoebae host models

Legionella pneumophila and tubercular Mycobacteria are the causative agents of potentially fatal diseases due to their pathogenesis but also to the emergence of antibiotic resistance that limits treatment strategies. The aim of our study is to explore the antimicrobial activity of a small ligand-based chemical library of 1,255 structurally diverse compounds. These compounds were screened in a combination of three assays, two monitoring the intracellular growth of the pathogenic bacteria, Mycobacterium marinum and L. pneumophila, and an additional anti-virulence \"plaque\" assay for M. marinum. We set up these assays using two amoeba strains, the genetically tractable Dictyostelium discoideum and the free-living amoeba Acanthamoeba castellanii. In summary, sixty-four compounds showed anti-infective/anti-virulence activity in at least one of the 3 assays. The intracellular assays hit rate varied between 1.7% (n=22) for M. marinum and 2.8% (n=35) for L pneumophila with 7 compounds in common between both pathogens. In parallel, 1.2 % (n= 15) of the tested compounds were able to restore D. discoideum growth in presence of M. marinum spiked in a lawn of Klebsiella pneumoniae. We also validated the generality of the hit compounds identified using the A. castellanii-M. marinum anti-infective screen in the powerful D. discoideum-M. marinum host-pathogen model. The characterization of anti-infective and antibacterial hits in the latter infection model revealed compounds able to reduce intracellular growth more than 50% at 30 M. Our studies underline the relevance of using a combination of low-cost and low-complexity assays with full 3R compliance associated with a rationalized focused library of compounds to help identifying new chemical scaffolds and dissect some of their properties prior to run further compounds development steps.

microbiology↗