Biology subjects

Frapy, E.

Publications and source records attributed to Frapy, E..

5 recordsLinked to original sources

bioRxiv2026

CBX3 Deletion Overcomes Ferroptosis Resistance in Colorectal Cancer by Targeting IFNγ/SLC7A11/SLC3A2 Axis

System Xc- (SLC7A11/SLC3A2) maintains redox balance by supporting glutathione synthesis, thereby preventing lipid peroxidation and ferroptosis, and represents a promising therapeutic target in cancer. In this work, we revealed that an important epigenetic regulator, CBX3 deletion significantly increased intracellular ROS and lipid ROS level following ferroptosis inducing, particularly under IFN{gamma} stimulation, thereby sensitized CRC cells to ferroptosis in vitro using human CRC cells as well as in vivo using MC38 syngenetic tumors. RNAseq with mice syngeneic tumors revealed an 11-gene oxidative stress signature downregulated in Cbx3KO tumors after combined treatment; its low expression score correlated with improved overall survival in CRC patients. Among them, Slc7a11, Ptgs2, and Cth were identified as CBX3 direct target genes. Additionally, several amino acid transporters functionally coupled to Xc- antiporter, as Slc3a2, Slc7a5, Slc1a5 and Slc6a9, all significantly decreased in Cbx3KO tumor under RSL3+IFN{gamma} treatment. Mechanistically, CBX3 binds directly to the promoter of Slc7a11 or Slc3a2 to sustain their expression and redox balance to resist ferroptosis in CRC. Knockout of CBX3 in CRC cells significantly impaired RNA polymerase II recruitment to the promoter of SLC7A11 or SLC3A2 and reduced SLC7A11 and SLC3A2 expression, an effect that was further exacerbated under IFN{gamma} stimulation but restored by STAT1 deletion. Overall, CBX3 protects CRC from oxidative stress by maintaining the functional integrity of IFN{gamma}/STAT1/SLC7A11/SLC3A2 axis, positioning CBX3 as a potential therapeutic target for enhancing ferroptosis therapies in CRC.

cancer biology↗

bioRxiv2025

The VapBC Toxin Antitoxin System Enhances Shigella flexneri Fitness Through Coordination of Metabolic Stress Adaptation and Virulence

Shigella flexneri is a facultative intracellular pathogen that causes bacillary dysentery by invading and replicating within intestinal epithelial cells. Successful intracellular survival requires the bacterium to balance metabolic adaptation with the sustained expression of virulence programs by the type III secretion system (T3SS). Toxin- antitoxin (TA) systems, including the highly conserved type II VapBC module, are classically associated with plasmid maintenance via post-segregational killing, but their broader roles during infection remain poorly understood. Here, we investigate the function of the VapBC system during S. flexneri infection. We show that the vapBC operon is activated in response to intracellular stress and that VapC-dependent cleavage of initiator tRNAfMet occurs specifically during infection. The stringent response, primarily mediated by SpoT, appears to influence operon responsiveness by maintaining vapB expression levels, while iron limitation emerges as a strong activator of vapC transcription and activity. Deletion of vapBC impairs T3SS activation and bacterial dissemination, despite normal invasion, and induces a strong host interferon response, including the upregulation of guanylate-binding proteins (GBPs), known to restrict bacterial spread. Transcriptomic profiling of the{Delta} vapBC mutant reveals downregulation of core metabolic genes and upregulation of envelope stress and other TA modules, indicating a loss of intracellular homeostasis. These findings uncover a novel role for VapBC in promoting Shigella fitness by coordinating stress adaptation, virulence expression, and immune evasion, thereby sustaining the bacteriums intracellular lifestyle.

microbiology↗

bioRxiv2022

Development of an antibody fused with an antimicrobial peptide targeting Pseudomonas aeruginosa: a new approach to prevent and treat bacterial infections

The increase of emerging drug resistant Gram-negative bacterial infections is of global concern. In addition, there is growing recognition that compromising the microbiota, through the use of broad spectrum antibiotics, may affect patient health in the long term. Therefore, there is the need to develop new -cidal strategies to combat Gram-negative infections that would consider these specific issues. In this study, we report and characterize one such approach, the antibody-drug conjugates (ADCs) that combine (i) targeting a specific pathogenic organism through a monoclonal antibody with (ii) the high killing activity of antimicrobial peptides. We focused on a major pathogenic Gram-negative bacterium associated with antibacterial resistance: Pseudomonas aeruginosa and designed an ADC by fusing an antimicrobial peptide at the C-terminal end of the VH and/or VL-chain of a monoclonal antibody, VSX, that targets the core of P. aeruginosa lipopolysaccharide (LPS). This ADC demonstrated appropriately minimal levels of toxicity to mammalian cells and rapidly kills P. aeruginosa strains through several mechanisms while protecting mice from P. aeruginosa lung infection when administered therapeutically. Furthermore, we found that the ADC was synergistic with several classes of antibiotics. This approach described in this study may result in a widely useful strategy to target specific pathogenic microorganisms without augmenting further antibiotic resistance. Author SummaryThe increasing of emerging drug resistant bacterial infections is a worldwide issue and infections caused by antibiotic resistant Gram-negative pathogens are particularly concerning. In addition, there is now growing recognition that disruption of the microbiota, through the use of broad spectrum antibiotics, may affect patient health in the long term. Therefore, there is the need to develop new -cidal strategies to combat Gram-negative infections while preserving the microbiota and also avoid enhancement of antibiotic resistance. We report and characterize here one such approach by using a specific monoclonal antibody associated with the potent killing activity of antimicrobial peptides in the form of an antibody-drug conjugate (ADC). The selected pathogenic bacterium was Pseudomonas aeruginosa, that presents numerous markers for both innate and acquired antibiotic resistance. The ADC lacked significant cytotoxicity against mammalian cells and was shown to be effective both in vitro and in vivo against P. aeruginosa.

microbiology↗

bioRxiv2022

Pre-clinical in vitro and in vivo characterization of a maternal vaccination before conception to protect against severe neonatal infections caused by Escherichia coli K1

Preterm birth remains the leading cause of neonatal morbidity and mortality today. Genetic, immunological, and infectious substrates are suspected. Preterm infants are at higher risk of severe neonatal infections and the main cause of bacterial infection in this population is Escherichia coli K1. Unfortunately, women with history of preterm birth have a high risk of recurrence. Therefore, these women constitute a target population for a vaccine, to date non-existent, against E. coli K1 to prevent these infections. In this study, we characterize the immunological and microbiological properties in adult female mice of a live attenuated vaccine candidate and the protection it conferred to newborn mice against severe infection caused by E. coli K1. We show that our E. coli K1 {Delta}aroA vaccine induces a strong immunity driven by polyclonal bactericidal antibodies. In our model of meningitis, pups born from mothers immunized before conception were strongly protected against different strains of E. coli K1 both in early-onset and late-onset diseases. Given the very high rate of mortality and neurological sequalae in neonatal meningitis caused by E. coli K1, this pre-clinical study provides a proof-of-concept for the development of a vaccine strategy against E. coli K1 severe infection in women at risk of preterm birth.

microbiology↗

bioRxiv2022

A high-throughput sequencing approach identifies immunotherapeutic targets for bacterial meningitis in neonates

BackgroundWorldwide, Escherichia coli is the leading cause of neonatal Gram-negative bacterial meningitis, but full understanding of the pathogenesis of this disease is not yet achieved. Moreover, to date, no vaccine is available against bacterial neonatal meningitis. MethodsHere, we used Transposon Sequencing of saturated banks of mutants (TnSeq) to evaluate E. coli K1 genetic fitness in murine neonatal meningitis. We identified E. coli K1 genes encoding for factors important for systemic dissemination and brain infection, and focused on products with a likely outer-membrane or extra-cellular localization, as these are potential vaccine candidates. We used in vitro and in vivo models to study the efficacy of active and passive immunization. ResultsWe selected for further study the conserved surface polysaccharide Poly-{beta}-(1-6)-N-Acetyl Glucosamine (PNAG), as a strong candidate for vaccine development. We found that PNAG was a virulence factor in our animal model. We showed that both passive and active immunization successfully prevented and/or treated meningitis caused by E. coli K1 in neonatal mice. We found an excellent opsonophagocytic killing activity of the antibodies to PNAG and in vitro these antibodies were also able to decrease binding, invasion and crossing of E. coli K1 through two blood brain barrier cell lines. Finally, to reinforce the potential of PNAG as a vaccine candidate in bacterial neonatal meningitis, we demonstrated that Group B Streptococcus, the main cause of neonatal meningitis in developed countries, also produced PNAG and that antibodies to PNAG could protect in vitro and in vivo against this major neonatal pathogen. InterpretationAltogether, these results indicate the utility of a high-throughput DNA sequencing method to identify potential immunotherapy targets for a pathogen, including in this study a potential broad-spectrum target for prevention of neonatal bacterial infections. FundingsANR Seq-N-Vaq, Charles Hood Foundation, Hearst Foundation. Groupe Pasteur Mutualite

microbiology↗