Biology subjects

Smani, Y.

Publications and source records attributed to Smani, Y..

7 recordsLinked to original sources

bioRxiv2026

OmpA controls intracellular survival of Acinetobacter baumannii through TFEB activation and lysosomal remodeling

Acinetobacter baumannii is a high-priority multidrug-resistant pathogen that survives within host cells by hijacking intracellular defense pathways. Here, we identify a previously unrecognized signaling axis linking bacterial invasion to host lysosomal regulation. We show that A. baumannii activates calcium-independent phospholipase A2 (iPLA2), leading to increased lysophosphatidylcholine (LPC) production and calcium influx through the ORAI1 channel, which together drive activation and nuclear translocation of the lysosomal transcription factor EB (TFEB). Pharmacological inhibition or genetic silencing of iPLA2 or ORAI1 markedly impaired TFEB activation and lysosomal biogenesis. Mechanistically, we demonstrate that this pathway is initiated by the outer membrane protein A (OmpA), which promotes bacterial invasion and enhances iPLA2 activity, LPC production, and downstream TFEB signaling. Despite induction of lysosomal biogenesis, A. baumannii persists intracellularly by producing ammonia and alkalinizing the lysosomal environment, thereby counteracting host antibacterial activity. In vivo, infection induces activation of HLH-30, the TFEB ortholog, in Caenorhabditis elegans in an OmpA-dependent manner. Together, our finding define an OmpA-iPLA2-LPC-ORAI1-TFEB signaling axis that coordinates host lipid and calcium signaling with lysosomal responses, while revealing a bacterial counterstrategy that promotes intracellular survival.

microbiology↗

bioRxiv2025

Discovery of a novel antibiotic class targeting the enolase of Acinetobacterbaumannii

High-throughput screening studies provide an additional approach to discovering repurposed drugs for antimicrobial treatments. In this work, we report the identification of ENOblock, an anticancer drug, as a novel antibiotic class. We computationally and experimentally validated that ENOblock synergizes with colistin, the last resort antibiotic, the colistin. Additionally, we identified enolase as the potential bacterial target for ENOblock. The in silico and in vitro antibacterial activity of ENOblock translated into potent in vivo efficacy in animal infection model. Collectively, the preclinical data support the selection of ENOblock as a promising candidate for antimicrobial development, with the potential to address the urgent threat of infections caused by Acinetobacter baumannii.

microbiology↗

bioRxiv2024

The defensome of Acinetobacter baumannii reveals two genome groups according to their innate defense systems and phage profile

Phages are guilty of killing daily almost half of bacterial cells, while bacteria have developed defense mechanisms that number in the dozens. Individual defense systems are gained and lost by genomes of the same species, depending on their fitness advantage. Thus, some genomes have a certain combination of defense systems, while other genomes act as a reservoir for the rest of the systems, thus constituting the so-called pan-immune system of the species. Here we have analyzed thousands of genomes of the bacterium Acinetobacter baumannii, an opportunistic pathogen of humans of great clinical concern, and we have found 81 different defense systems heterogeneously distributed. By analyzing how these systems combine, we have found that more than half of the genomes lack the universal DNA-methylating restriction-modification systems (R-M) and harbor an alternative innate SspBCDE system that performs a DNA phosphorothioate modification. In addition, the adaptive CRISPR-Cas systems could act synergistically to the R-M systems, based on their frequency of co-appearance. The presence of one or the other innate system could modulate the evolution of the genomes of this species, causing them to present a different profile of phages integrated into the bacterial genome. We have also observed that the presence of many defense systems is associated with the presence of a higher number of prophages, which could be due to the fact that the prophage carries the system, or that the bacterium would not need these systems in environments where the phage is absent.

microbiology↗

bioRxiv2024

Antibacterial activity of tamoxifen derivatives against methicillin-resistant Staphylococcus aureus

The present work aimed to discover new tamoxifen derivatives with antimicrobial potential, particularly targeting methicillin-resistant Staphylococcus aureus (MRSA). The MIC of 22 tamoxifen derivatives was determined against S. aureus reference and MRSA strains, using microdilution assays. The antibacterial effects of selected tamoxifen derivatives against MRSA (USA7) were assessed through bacterial growth assays. Bacterial membrane permeability and molecular docking assays were performed. The MIC of the tamoxifen derivatives against MRSA ranged from to 16 to >64 g/mL. Bacterial growth assays demonstrated that tamoxifen derivatives 2, 5, and 6 reduced dose-dependently the growth of the USA7 strain. Moreover, treatment of MRSA with derivatives 2 and 5 resulted in increased membrane permeabilization without being the cell wall their molecular target. These data suggest that tamoxifen derivatives exhibit antibacterial activity against MRSA, potentially broadening the spectrum of available drug treatments for combating antimicrobial-resistant Gram-positive bacteria. ImportanceThe development of new antimicrobial therapeutic strategies requires immediate attention to avoid the tens of millions of deaths predicted to occur by 2050 as a result of multidrug-resistant (MDR) bacterial infections. In this study, we assessed the antibacterial activity of 22 tamoxifen derivatives against methicillin-resistant Staphylococcus aureus (MRSA). We found that three tamoxifen derivatives exhibited antibacterial activity against MRSA clinical isolats, presenting MIC50 values between 16 and 64 g/mL and reducing bacterial growth over 24 h. Additionally, this antibacterial activity for two of the derivatives was accompanied by increased membrane permeability of MRSA. Our results suggest that tamoxifen derivatives might be used as a potential therapeutic alternative for treating MRSA strains in an animal model of infection.

microbiology↗

bioRxiv2021

Repurposing of the tamoxifen metabolites to treat methicillin-resistant Staphylococcus epidermidis and vancomycin-resistant Enterococcus faecalis infections

Repurposing drugs provides a new approach to the fight against multidrug-resistant (MDR) bacteria. We have reported that three major tamoxifen metabolites, N-desmethyltamoxifen (DTAM), 4-hydroxytamoxifen (HTAM) and endoxifen (ENDX), presented bactericidal activity against Acinetobacter baumannii and Escherichia coli. Here, we aimed to analyse the activity of a mixture of the three tamoxifen metabolites against methicillin-resistant Staphylococcus epidermidis (MRSE) and Enterococcus spp. MRSE (n=17) and Enterococcus spp. (E. faecalis n=8, and E. faecium n=10) strains were used. MIC of the mixture of DTAM, HTAM and ENDX, and vancomycin were determined by microdilution assay. The bactericidal activity of the three metabolites together and vancomycin against MRSE (SE385 and SE742) and vancomycin-resistant E. faecalis (EVR1 and EVR2) strains was determined by time-kill curve assays. Finally, changes in membrane permeability of SE742 and EVR1 strains were analyzed using fluorescence assays. MIC50 and MIC90 of tamoxifen metabolites were 1 mg/L for MRSE strains and 2 mg/L for Enterococcus spp. strains. In the time-killing assays, tamoxifen metabolites mixture showed bactericidal activity at 2x and 4xMIC for MRSE (SE385 and SE742) and E. faecalis (EVR1 and EVR2) strains. This antimicrobial activity of tamoxifen metabolites paralleled an increased membrane permeability of SE385 and EVR2 strains. Altogether, these results showed that tamoxifen metabolites presented antibacterial activity against MRSE and vancomycin-resistant E. faecalis, suggesting that tamoxifen metabolites might increase the arsenal of drugs treatment against these bacterial pathogens.

microbiology↗

bioRxiv2020

Efficacy of lysophosphatidylcholine as direct treatment in combination with colistin against Acinetobacter baumannii in murine severe infections models

ObjectivesThe stimulation of the immune response to prevent the progression of the infection may be an adjuvant to antimicrobial treatment. Previously, we showed that preemptive treatment with lysophosphatidylcholine (LPC) in combination with colistin improved the therapeutic efficacy of colistin against MDR Acinetobacter baumannii. In this study, we aimed to evaluate the efficacy of direct treatment with LPC in combination with colistin in murine experimental models of severe infections by A. baumannii. MethodsWe used A. baumannii strain Ab9, which is susceptible to colistin and most of the antibiotics used in clinical settings, and A. baumannii strain Ab186, which is susceptible to colistin but presents a MDR pattern. The therapeutic efficacies of one and two doses of LPC (25 mg/kg/d) and colistin (20 mg/kg/8h), alone or in combination, were assessed against Ab9 and Ab186 in murine peritoneal sepsis and pneumonia models. ResultsOne and two doses of LPC in combination with colistin and colistin monotherapy enhanced bacterial clearance of Ab9 and Ab186 from spleen, lungs and blood and reduced mortality rates compared with those of the non-treated mice group in both experimental models (P<0.05). Moreover, one and two doses of LPC reduced the bacterial concentration in tissues and blood in both models, and increased mice survival in peritoneal sepsis model for both strains compared with those of colistin monotherapy group. ConclusionsLPC used as an adjuvant of colistin treatment may be helpful to reduce the severity and the resolution of the infection by MDR A. baumannii.

microbiology↗

bioRxiv2020

Tamoxifen repurposing to combat infections by multidrug-resistant Gram-negative bacilli

The development of new strategic therapies for multidrug-resistant bacteria, like the use of non-antimicrobial approaches and/or drugs repurposing to be used as monotherapies or in combination with clinically relevant antibiotics, has become an urgent need. A therapeutic alternative for infections by multidrug-resistant Gram-negative bacilli (MDR-GNB) is immune system modulation to improve the infection clearance. We showed that immunocompetent mice infected by Acinetobacter baumannii, Pseudomonas aeruginosa or Escherichia coli in peritoneal sepsis models and treated with tamoxifen at 80 mg/kg/d for three days reduced the release of MCP-1 and its signalling pathway IL-18 and phosphorylated ERK1/2. This reduction of MCP-1 induced the reduction of migration of inflammatory monocytes and neutrophils from bone marrow to blood. Indeed, the treatment with tamoxifen in murine peritoneal sepsis models reduced the bacterial load in tissues and blood; and increased the mice survival from 0% to 60-100%. Tamoxifen treatment of neutropenic mice infected by these pathogens increased mice survival up to 20-60%. Furthermore, susceptibility and time-kill assays showed that the metabolites of tamoxifen, N-desmethyltamoxifen, hydroxytamoxifen and endoxifen, the three together exhibited MIC90 values of 16 mg/L and were bactericidal against clinical isolates of A. baumannii and E. coli. This antimicrobial activity of tamoxifen metabolites parallels an increased membrane permeability of A. baumannii and E. coli without affecting their outer membrane proteins profiles. Together, these data showed that tamoxifen present a therapeutic efficacy against MDR A. baumannii, P. aeruginosa and E. coli in experimental models of infections and can be repurposed as new treatment for GNB infections. ImportanceAntimicrobial resistance in Gram-negative bacilli (GNB) is a global health treat. Drug repurposing, a novel approach involving the search of new indications for FDA approved drugs is gaining interest. Among them, we found the anti-cancer drug tamoxifen, which presents very promising therapeutic efficacy. The current study showed that tamoxifen presents activity in animal models of infection with MDR Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli by modulating the traffic of innate immune system cells and the antibacterial activity presented by its three major metabolites produced in vivo against these GNB. Our results offer a new candidate to be repurposed to treat severe infections caused by these pathogens.

microbiology↗