Biology subjects

Mangoni, M. L.

Publications and source records attributed to Mangoni, M. L..

3 recordsLinked to original sources

bioRxiv2025

Antimicrobial Peptides Induce Cell Death in Marginal Zone Lymphoma Models Resistant to Targeted Therapies

Marginal zone lymphoma (MZL) is an indolent yet incurable B-cell malignancy in which targeted agents such as BTK and PI3K inhibitors frequently fail due to resistance or toxicity. Antimicrobial peptides (AMPs), evolutionarily conserved effectors of innate immunity, possess selective cytotoxicity against malignant cells by exploiting tumor-specific membrane alterations. We evaluated the antitumor activity of seven natural AMPs, including Antarctic fish-derived trematocines and chionodracine variants, and amphibian temporins, against MZL cell lines (VL51, Karpas1718) and derivatives resistant to BTK, PI3K{delta}, or PI3K/{delta} inhibitors. Among them, W-trematocine and temporin L demonstrated potent dose-dependent cytotoxicity with IC50 values of 5.7-10 M, maintaining full activity in all resistant models. Other peptides showed moderate activity, while chionodracine-1 was inactive. Notably, W-trematocine displayed minimal toxicity toward non-malignant cells in prior studies, underscoring its selectivity. AMP-mediated killing, driven by membrane disruption and non-apoptotic death pathways, bypassed conventional resistance mechanisms, suggesting therapeutic potential in relapsed/refractory disease. These findings highlight natural AMPs as promising candidates for development in drug-resistant MZL, warranting further optimization and preclinical validation.

cancer biology↗

bioRxiv2022

Rapid assessment of susceptibility of bacteria and erythrocytes to antimicrobial peptides by single-cell impedance cytometry

Antimicrobial peptides (AMPs) represent a promising class of compounds to fight antibiotic-resistant infections. In most cases, they kill bacteria by making their membrane permeable and therefore exhibit low propensity to induce bacterial resistance. In addition, they are often selective, killing bacteria at concentrations lower than those at which they are toxic to the host. However, clinical applications of AMPs are hindered by a limited understanding of their interactions with bacteria and human cells. Standard susceptibility testing methods are based on the analysis of the growth of a bacterial population and therefore require several hours. Moreover, different assays are required to assess the toxicity to host cells. In this work, we propose the use of microfluidic impedance cytometry to explore the action of AMPs on both bacteria and host cells, in a rapid manner and with single-cell resolution. We show that the electrical signatures of Bacillus megaterium (B. megaterium) cells and human red blood cells (RBCs) reflect the action of a representative antimicrobial peptide, DNS-PMAP23. In particular, the impedance phase at high frequency (e.g., 11 or 20 MHz) is a reliable label-free metric for monitoring DNS-PMAP23 bactericidal activity and toxicity to RBCs. The impedance-based characterization is validated by comparison with standard antibacterial activity assays and absorbance-based hemolytic activity assays. Furthermore, we demonstrate the applicability of the technique to a mixed sample of B. megaterium cells and RBCs, which paves the way to study AMP selectivity for bacterial versus eukaryotic cells in presence of both cell types.

biophysics↗

bioRxiv2020

Inoculum effect of antimicrobial peptides

The activity of many antibiotics depends on the initial density of cells used in bacteria growth inhibition assays. This phenomenon, termed the inoculum effect, can have important consequences for the therapeutic efficacy of the drugs, since bacterial loads vary by several orders of magnitude in clinically relevant infections. Antimicrobial peptides are a promising class of molecules to fight drug-resistant bacteria, since they act mainly by perturbing the cell membranes rather than by inhibiting intracellular targets. Here we report the first systematic characterization of the inoculum effect for this class of antibacterial compounds. Thirteen peptides (including all-D enantiomers) and peptidomimetics were analyzed by measuring minimum inhibitory concentration values, covering more than 7 orders of magnitude in inoculated cell density. In all cases, we observed a significant inoculum effect for cell densities above 5 x 104 cells/mL, while the active concentrations remained constant (within the micromolar range) for lower densities. In the case of membrane-active peptides, these data can be rationalized by considering a simple model, taking into account peptide-cell association and hypothesizing that a threshold number of cell-bound peptide molecules is required in order to cause a killing effect. The observed effects question the clinical utility of activity and selectivity determinations performed at a fixed, standardized cell density. A routine evaluation of the inoculum dependence of the activity of antimicrobial peptides and peptidomimetics should be considered. Significance statementBacterial drug resistance is a crucial threat to global health and antimicrobials with novel mechanisms of action are severely needed. Antimicrobial peptides are natural molecules that kill bacteria mostly by perturbing their membranes and represent promising compounds to fight resistant microbes. Their activity is normally tested under standardized conditions of bacterial density. However, the bacterial load in clinically relevant infections varies by many orders of magnitude. Here we showed that the minimum peptide concentration needed for bacterial killing can vary by more than 100 times with an increase in the density of cells in the initial inoculum of the assay (inoculum effect) These findings question utility of the presently used activity screening assays and our current understanding of antimicrobial peptides.

biophysics↗