Biology subjects

Deboosere, N.

Publications and source records attributed to Deboosere, N..

4 recordsLinked to original sources

bioRxiv2026

Galectin-3 recruitment at the Mycobacterium tuberculosis-containing phagosome is critical in macrophage but dispensable in epithelial cells

Mycobacterium tuberculosis (Mtb) virulence relies in part on its ability to induce phagosomal membrane rupture, enabling bacterial access to the host cell cytosol. This process is largely mediated by the ESX-1 secretion system, which is present in Mtb but absent from the vaccine strain BCG. Galectin-3 (Gal3), a {beta}-galactoside-binding lectin, is recruited to damaged endomembranes and functions as a cytosolic sensor of membrane disruption. However, the kinetics and quantitative features of Gal3 recruitment to Mtb-containing vacuoles have remained poorly characterized. Here, we performed a longitudinal quantitative imaging study of Gal3 recruitment in human macrophages over a five-day infection period. Gal3 was recruited to mycobacteria-containing vacuoles shortly after infection with both live and heat-killed Mtb. Differences between the two conditions emerged from day 1 post-infection and persisted until macrophage death. A similar kinetic profile was observed with recombinant BCG::ESX-1, whereas parental BCG failed to induce Gal3 recruitment, confirming the requirement for ESX-1-dependent membrane damage. Cytoplasmic Gal3 levels were higher in bystander macrophages than in infected cells and were comparable to non-infected controls, suggesting that diffuse cytoplasmic Gal3 is associated with cells lacking intracellular mycobacteria. Functional studies revealed that Gal3 silencing enhanced long-term intracellular Mtb replication, demonstrating a role for Gal3 in restricting bacterial growth. Importantly, Gal3 recruitment was not observed in alveolar epithelial cells. This cell-type specificity was confirmed in a microfluidic alveolus-on-chip model. Together, these findings identify sustained Gal3 recruitment to the mycobacteria-containing vacuole as a robust quantitative marker of ESX-1-dependent phagosomal rupture and Mtb virulence.

microbiology↗

bioRxiv2021

Large scale screening discovers clofoctol as an inhibitor of SARS-CoV-2 replication that reduces COVID-19-like pathology

Drug repurposing has the advantage of shortening regulatory preclinical development steps. Here, we screened a library of drug compounds, already registered in one or several geographical areas, to identify those exhibiting antiviral activity against SARS-CoV-2 with relevant potency. Of the 1,942 compounds tested, 21 exhibited a substantial antiviral activity in Vero-81 cells. Among them, clofoctol, an antibacterial drug used for the treatment of bacterial respiratory tract infections, was further investigated due to favorable safety profile and pharmacokinetic properties. Notably, the peak concentration of clofoctol that can be achieved in human lungs is more than 20 times higher than its IC50 measured against SARS-CoV-2 in human pulmonary cells. This compound inhibits SARS-CoV-2 at a post-entry step. Lastly, therapeutic treatment of human ACE2 receptor transgenic mice decreased viral load, reduced inflammatory gene expression and lowered pulmonary pathology. Altogether, these data strongly support clofoctol as a therapeutic candidate for the treatment of COVID-19 patients. SummaryAntivirals targeting SARS-CoV-2 are sorely needed. In this study, we screened a library of drug compounds and identified clofoctol as an antiviral against SARS-CoV-2. We further demonstrated that, in vivo, this compound reduces inflammatory gene expression and lowers pulmonary pathology.

microbiology↗

bioRxiv2021

A high content microscopy screening identifies genes involved in cell width control in Bacillus subtilis

How cells control their shape and size is a fundamental question of biology. In most bacteria, cell shape is imposed by the peptidoglycan (PG) polymeric meshwork that surrounds the cell. Thus, bacterial cell morphogenesis results from the coordinated action of the proteins assembling and degrading the PG shell. Remarkably, during steady-state growth, most bacteria maintain a defined shape along generations, suggesting that error-proof mechanisms tightly control the process. In the rod-shaped model for Gram-positive bacteria Bacillus subtilis, the average cell length varies as a function of the growth rate but the cell diameter remains constant throughout the cell cycle and across growth conditions. Here, in an attempt to shed light on the cellular circuits controlling bacterial cell width, we developed a screen to identify genetic determinants of cell width in B. subtilis. Using high-content screening (HCS) fluorescence microscopy and semi-automated measurement of single-cell dimensions, we screened a library of ~ 4000 single knockout mutants. We identified 13 mutations significantly altering cell diameter, in genes that belong to several functional groups. In particular, our results indicate that metabolism plays a major role in cell width control in B. subtilis.

microbiology↗

bioRxiv2019

IRG1 controls immunometabolic host response and restricts intracellular Mycobacterium tuberculosis infection

Mycobacterium tuberculosis (Mtb), the pathogen causing human tuberculosis, has evolved multiple strategies to successfully prevent clearance by immune cells and to establish dissemination and long-term survival in the host. The modulation of host immunity to maximize pathogen elimination while minimizing inflammation-mediated tissue damage may provide another tool to fight drug-resistant Mtb strains. Metabolic reprogramming of phagocytes can dramatically influence the intracellular colonization by Mtb and the key players involved in this process remain a matter of debate. Here, we demonstrate that aconitate decarboxylase 1 (Acod1; also known as immune-responsive gene 1, IRG1), which converts cis-aconitate into the metabolite itaconate, is a major player in controlling the acute phase of Mtb infection. Exposure of IRG1-deficient mice to a virulent Mtb strain (H37Rv) was lethal, while M. bovis BCG and the H37Ra attenuated Mtb strain induced neither lethality nor severe lung immunopathology. Lungs of IRG1-deficient mice infected by Mtb H37Rv displayed large areas of necrotizing granulomatous inflammation and neutrophil infiltration, accompanied by reduced levels of B and T lymphocytes and increased levels of alveolar and interstitial macrophage populations, compared to their wild type counterparts. Next, we show that IRG1, beyond its recruitment to Mtb-containing vacuoles, restricts Mtb replication and lipid droplets accumulation in phagocytes, hallmarks of a tight interplay between the bacillus and the host. Altogether, IRG1 confines the host response to create a favourable phagocytic environment for Mtb controlled intracellular replication.

immunology↗