Biology subjects

Falciani, C.

Publications and source records attributed to Falciani, C..

4 recordsLinked to original sources

bioRxiv2025

Establishment and application of a vesicle extraction method for clinical strains of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a versatile pathogen capable of causing illnesses that range from mild infections to life-threatening conditions. Its virulence is driven by a wide array of factors, among which extracellular vesicles (EVs) have gained recognition as important contributors to its pathogenicity. Despite this, the full scope of their roles remains unclear. A major barrier to EV characterization is the difficulty of vesicle isolation--procedures are often lengthy, yield is low, and specialized equipment is required. In this study, we assessed the effectiveness of a rapid vesicle extraction method from clinical strains of P. aeruginosa. To that end, we first selected and characterized six phenotypically diverse clinical strains of P. aeruginosa (two reference strains and 4 clinical isolates, including one strain from a cystic fibrosis patient) and used them to evaluate the vesicle extraction method. The results obtained through SDS-PAGE analysis, western blot, protein quantification, and TEM indicated the presence of vesicles in all samples; however, it was also possible to observe a large number of contaminants in some of them (mainly LS07 and Z37). Subsequent treatment with enzymes (DNase and/or alginate lyase) allowed for the elimination of the contaminants as observed by electron microscopy. Our results suggest that the method is suited for the vesicle extraction of clinical isolates of P. aeruginosa. The phenotypic complexity of these strains presents challenges that current rapid purification methods are ill-equipped to handle, highlighting the need for improved or alternative approaches.

microbiology↗

bioRxiv2025

SET-M33 peptide as a selective in vitro antimicrobial agent against the porcine respiratory pathogen Glaesserella parasuis

As we face the threat from bacterial pathogens that are resistant to many conventional antibiotics, many current research efforts focus on expanding our arsenal of antimicrobial compounds. However, identifying use cases in which such new antimicrobials can effectively target pathogens while minimizing collateral damage in the commensal microbiota remains a challenge. To tackle this challenge, we focused on one new antimicrobial, the synthetic antimicrobial peptide SET-M33, and examined its ability to target porcine respiratory pathogens and a collection of porcine commensal nasal microbiota members in vitro. Our experiments revealed three key results. First, there were large differences in SET-M33 sensitivity across the tested strains. In particular, pathogenic Glaesserella parasuis was highly sensitive to SET-M33 at concentrations that did not affect the growth of most commensal strains. Second, some of the tested commensal strains (i.e. Rothia nasimurium and Staphylococcus aureus) were able to inactivate SET-M33 during in vitro cultivation. Third, despite this potential for SET-M33 inactivation by commensal strains, SET-M33 was still able to selectively eliminate pathogenic G. parasuis from in vitro co-cultures that also contained R. nasimurium. Overall, this study highlights the substantial complexity that emerges from the interplay between antimicrobials, pathogens, and commensals, even within a comparatively simple in vitro system, and provides a template for identifying suitable use cases for newly developed antimicrobials.

microbiology↗

bioRxiv2024

Branched Oncolytic Peptides Target HSPGs, Inhibit Metastasis, and Trigger the Release of Molecular Determinants of Immunogenic Cell Death in Pancreatic Cancer.

Immunogenic cell death (ICD) can be exploited to treat non-immunoreactive tumors that do not respond to current standard and innovative therapies. Not all chemotherapeutics trigger ICD, among those that do exert this effect, there are anthracyclines, irinotecan, some platinum derivatives and oncolytic peptides. We studied two new branched oncolytic peptides, BOP7 and BOP9 that proved to elicit the release of damage-associated molecular patterns DAMPS, mediators of ICD, in pancreatic cancer cells. The two BOPs selectively bound and killed tumor cells, particularly PANC-1 and Mia PaCa-2, but not cells of non-tumor origin such as RAW 264.7, CHO-K1 and pgsA-745. The cancer selectivity of the two BOPs may be attributed to their repeated cationic sequences, which enable multivalent binding to heparan sulfate glycosaminoglycans (HSPGs), bearing multiple anionic sulfation patterns on cancer cells. This interaction of BOPs with HSPGs not only fosters an anti-metastatic effect in vitro, as demonstrated by reduced adhesion and migration of PANC-1 cancer cells, but also shows promising tumor-specific cytotoxicity and low hemolytic activity. Remarkably, the cytotoxicity induced by BOPs triggers the release of DAMPs, particularly HMGB1, IFN-{beta} and ATP, by dying cells, persisting longer than the cytotoxicity of conventional chemotherapeutic agents such as irinotecan and daunorubicin. An in vivo assay in nude mice showed an encouraging 20% inhibition of tumor grafting and growth in a pancreatic cancer model by BOP9.

biochemistry↗

bioRxiv2024

A compact prism-based microscope for high sensitive measurements in fluid biopsy

The increasing demand for sensitive, portable, and cost-effective disease detection methods has raised significant interest in the development of biosensors for rapid and early-stage diagnosis, population mass-screening, and bedside monitoring. Although a certain number of sensing devices with high sensitivity has experienced considerable progress, their practical application has been hindered by challenges in replicating instrumental systems, obtaining rapid and multiplexed signals, and the high cost of manufacturing. In response, we present a streamlined prism-based Total Internal Reflection system which, in combination with surface functionalization techniques on gold nanoparticles, is capable of facilitating Evanescent Wave scattering for the highly sensitive and rapid detection of specific analytes in synthetic liquids and real human samples. The system achieves a remarkable limit of detection of 1 fg/mL concentration for the targeted pathological biomarker. Our innovative design addresses the limitations of existing technologies by reducing costs, minimising overall size, and ensuring swift biofluid analysis with remarkable sensitivity. To validate its efficacy, we conducted scattering experiments in synthetic and human serum samples, exploiting functionalized AuNPs to recognize bacterial lipopolysaccharides as biomarkers for sepsis disease. The cohesive integration of these techniques hopefully makes this biosensing setup a promising candidate for potential clinical deployment, meeting the pressing requirements for rapid personalised diagnosis, large-scale population screening and bed-monitoring.

biophysics↗