Altered Cell Membrane Research Articles

Membrane Phenotypic, Metabolic and Genotypic Adaptations of Streptococcus oralis Strains Destined to Rapidly Develop Stable, High-Level Daptomycin Resistance during Daptomycin Exposures.

The Streptococcus mitis-oralis subgroup of viridans group streptococci are important human pathogens. We previously showed that a substantial portion of S. mitis-oralis strains (>25%) are 'destined' to develop rapid, high-level, and stable daptomycin (DAP) resistance (DAP-R) during DAP exposures in vitro. Such DAP-R is often accompanied by perturbations in distinct membrane phenotypes and metabolic pathways. The current study evaluated two S. oralis bloodstream isolates, 73 and 205. Strain 73 developed stable, high-level DAP-R (minimum inhibitory concentration [MIC] > 256 µg/mL) within 2 days of in vitro DAP passage ("high level" DAP-R [HLDR]). In contrast, strain 205 evolved low-level and unstable DAP-R (MIC = 8 µg/mL) under the same exposure conditions in vitro ("non-HLDR"). Comparing the parental 73 vs. 73-D2 (HLDR) strain-pair, we observed the 73-D2 had the following major differences: (i) altered cell membrane (CM) phospholipid profiles, featuring the disappearance of phosphatidylglycerol (PG) and cardiolipin (CL), with accumulation of the PG-CL pathway precursor, phosphatidic acid (PA); (ii) enhanced CM fluidity; (iii) increased DAP surface binding; (iv) reduced growth rates; (v) decreased glucose utilization and lactate accumulation; and (vi) increased enzymatic activity within the glycolytic (i.e., lactate dehydrogenase [LDH]) and lipid biosynthetic (glycerol-3-phosphate dehydrogenase [GPDH]) pathways. In contrast, the 205 (non-HLDR) strain-pair did not show these same phenotypic or metabolic changes over the 2-day DAP exposure. WGS analyses confirmed the presence of mutations in genes involved in the above glycolytic and phospholipid biosynthetic pathways in the 73-D2 passage variant. These data suggest that S. oralis strains which are 'destined' to rapidly develop HLDR do so via a conserved cadre of genotypic, membrane phenotypic, and metabolic adaptations.

Variability of extracellular vesicle release during storage of red blood cell concentrates is associated with differential membrane alterations, including loss of cholesterol-enriched domains.

Transfusion of red blood cell concentrates is the most common medical procedure to treat anaemia. However, their storage is associated with development of storage lesions, including the release of extracellular vesicles. These vesicles affect in vivo viability and functionality of transfused red blood cells and appear responsible for adverse post-transfusional complications. However, the biogenesis and release mechanisms are not fully understood. We here addressed this issue by comparing the kinetics and extents of extracellular vesicle release as well as red blood cell metabolic, oxidative and membrane alterations upon storage in 38 concentrates. We showed that extracellular vesicle abundance increased exponentially during storage. The 38 concentrates contained on average 7 × 1012 extracellular vesicles at 6weeks (w) but displayed a ∼40-fold variability. These concentrates were subsequently classified into 3 cohorts based on their vesiculation rate. The variability in extracellular vesicle release was not associated with a differential red blood cell ATP content or with increased oxidative stress (in the form of reactive oxygen species, methaemoglobin and band3 integrity) but rather with red blood cell membrane modifications, i.e., cytoskeleton membrane occupancy, lateral heterogeneity in lipid domains and transversal asymmetry. Indeed, no changes were noticed in the low vesiculation group until 6w while the medium and the high vesiculation groups exhibited a decrease in spectrin membrane occupancy between 3 and 6w and an increase of sphingomyelin-enriched domain abundance from 5w and of phosphatidylserine surface exposure from 8w. Moreover, each vesiculation group showed a decrease of cholesterol-enriched domains associated with a cholesterol content increase in extracellular vesicles but at different storage time points. This observation suggested that cholesterol-enriched domains could represent a starting point for vesiculation. Altogether, our data reveal for the first time that the differential extent of extracellular vesicle release in red blood cell concentrates did not simply result from preparation method, storage conditions or technical issues but was linked to membrane alterations.

Riluzole, a Derivative of Benzothiazole as a Potential Anti-Amoebic Agent against Entamoeba histolytica.

Amoebiasis is produced by the parasite Entamoeba histolytica; this disease affects millions of people throughout the world who may suffer from amoebic colitis or amoebic liver abscess. Metronidazole is used to treat this protozoan, but it causes important adverse effects that limit its use. Studies have shown that riluzole has demonstrated activity against some parasites. Thus, the present study aimed, for the first time, to demonstrate the in vitro and in silico anti-amoebic activity of riluzole. In vitro, the results of Entamoeba histolytica trophozoites treated with IC50 (319.5 μM) of riluzole for 5 h showed (i) a decrease of 48.1% in amoeba viability, (ii) ultrastructural changes such as a loss of plasma membrane continuity and alterations in the nuclei followed by lysis, (iii) apoptosis-like cell death, (iv) the triggering of the production of reactive oxygen species and nitric oxide, and (v) the downregulation of amoebic antioxidant enzyme gene expression. Interestingly, docking studies have indicated that riluzole presented a higher affinity than metronidazole for the antioxidant enzymes thioredoxin, thioredoxin reductase, rubrerythrin, and peroxiredoxin of Entamoeba histolytica, which are considered as possible candidates of molecular targets. Our results suggest that riluzole could be an alternative treatment against Entamoeba histolytica. Future studies should be conducted to analyze the in vivo riluzole anti-amoebic effect on the resolution of amebic liver abscess in a susceptible model, as this will contribute to developing new therapeutic agents with anti-amoebic activity.

Psidium guajava (Myrtaceae) re-sensitizes multidrug-resistant Pseudomonas aeruginosa over-expressing MexAB-OprM efflux pumps to commonly prescribed antibiotics

Abstract Background: Pseudomonas aeruginosa is a critical-class priority pathogen showing high resistance to almost all classes of conventional antibiotics. As a result, discovering new drugs capable of combating Pseudomonas infections becomes critical. The current study looked at the antibacterial and antibiotic-resistance reversal properties of the leaf (PGL) and bark (PGB) methanol extracts of Psidium guajava (Myrtaceae), a popular food plant, towards multidrug-resistant (MDR) P. aeruginosa over-expressing active efflux. Methods: The activities were assessed using a 96-well plate microdilution technique, with iodonitrotetrazolium chloride (INT) to detect living bacteria. The action of herbals was further carried out on Pseudomonas kinetic growth, cell membrane, and H+-ATPase mediated proton pumps, using standards. Results: PGL and PGB produced inhibitory effects on all the fourteen MDR strains and clinical isolates of P. aeruginosa, with the minimum inhibitory concentrations (MIC) recorded ranging from 64 to 2048 μg/mL. PGB was shown to be more effective, having MICs ≤ 512 μg/mL on 100% of the MDR pathogens tested. It also exhibited the lowest MICs (best activity) of 64 μg/mL against three MDR clinical isolates P124, P57, and P29, with activity higher than that of the reference medication (chloramphenicol). PGL and PGB were shown to have significant antibiotic-resistance reversal action when combined with conventional antibiotics, with PGB enhancing the efficacy of all standard drugs employed. PGB was shown to lengthen the latent phase of kinetic growth, also, it significantly inhibited the H+-ATPase-mediated proton pump and altered cell membrane integrity, at MIC and 2×MIC. Conclusion: The current investigation provides justification for considering P. guajava extracts, alone or in combination with antibiotics, as potential treatments for MDR P. aeruginosa infections. Keywords: Antibiotics; efflux pumps; food plants; multidrug-resistant bacteria; Pseudomonas aeruginosa; Psidium guajava.

Breaking Down Tumor Drug Resistance: The Link Between Cell Membrane Changes and Treatment Efficacy

Abstract There have been significant advances in our understanding of how changes in the fluidity and permeability of the cell membrane can affect drug resistance in cancer. Research has shown that cancer cells often have changes in the fluidity and permeability of their cell membrane that contribute to their resistance to drugs used to treat cancer. These changes may be due to changes in the composition and organization of the lipid bilayer that makes up the membrane, as well as changes in the expression or localization of proteins and other molecules embedded in the membrane. The lipid composition in the tumor cell membrane changes with drug resistance, which can affect the fluidity and permeability of the cell membrane. Reversal of drug resistance can be achieved by altering cell membrane fluidity and permeability. In recent years, there have been numerous studies aimed at understanding the mechanisms underlying these changes and identifying strategies to overcome drug resistance in cancer. This research has led to the development of new drugs and drug delivery systems that are designed to target specific changes in the cell membrane of cancer cells and improve the effectiveness of chemotherapy. Overall, the advances in our understanding of the role of cell membrane fluidity and permeability in drug resistance in cancer have led to the development of new approaches to treat cancer and improve patient outcomes and further research is needed to continue to improve the understanding of these mechanisms and to identify new strategies to overcome drug resistance in cancer. This article highlights the research status and detection methods of cell membrane fluidity and permeability affecting tumor drug resistance.

Terahertz Spectroscopy Sheds Light on Real-Time Exchange Kinetics Occurring through Plasma Membrane during Photodynamic Therapy Treatment.

Methods to follow in real time complex processes occurring along living cell membranes such as cell permeabilization are rare. Here, the terahertz spectroscopy reveals early events in plasma membrane alteration generated during photodynamic therapy (PDT) protocol, events which are not observable in any other conventional biological techniques performed in parallel as comparison. Photodynamic process is examined in Madin-Darby canine kidney cells using Pheophorbide (Pheo) photosensitizer alone or alternatively encapsulated in poly(ethylene oxide)-block-poly(ε-caprolactone) micelles for drug delivery purpose. Terahertz spectroscopy (THz) reveals that plasma membrane permeabilization starts simultaneously with illumination and is stronger when photosensitizer is encapsulated. In parallel, the exchange of biological species is assessed. Over several hours, this conventional approach demonstrates significant differences between free and encapsulated Pheo, the latter leading to high penetration of propidium iodide, Na+ and Ca2+ ions, and a high level of leakage of K+ , ATP, and lactate dehydrogenase. THz spectroscopy provides, in a single measurement, the relative number of defects per membrane surface created after PDT, which is not achieved by any other method, providing early, sensitive real-time information. THz spectroscopy is therefore a promising technique and can be applied to any biological topic requiring the examination of short-term plasma membrane permeabilization.

Adjunctive inhaled amikacin in infants with Ventilator-Associated Pneumonia optimizes the complex antimicrobial therapy: pilot study.

VAP remains the second leading cause of death among the patients with nosocomial infections and its incidence varies significantly from 5% to 60% reaching on average 10 %. It is of crucial importance to develop novel treatment approaches and optimize the existing ones. Thus, the aim of this pilot study was to study the laboratory-microbiological effect of inhaled aminoglycosides in a complex treatment of patients with ventilator-associatedpneumonia(VAP). Methods: To study the laboratory-microbiological effect of adjunctive inhaled aminoglycosides in the treatment of VAP, twenty enrolled patients were randomly subdivided into 2 groups (n=10). Amikacin was administered via a nebulizer starting from the first day of VAP manifestation. Inhalations were performed BID for 7 days via a nebulizer integrated into the breathing circuit. We assessed: cell membrane alterations in leukocytes, Annexin V/7-AAD staining for leukocytes, ROS detection assay for leukocytes. Adjunctive administration of inhaled amikacin reduced the fluorescence intensity ratio more efficiently compared with the intravenous antimicrobial treatment with no aerosolized amikacin following both 48 h and 96 h of treatment. The amount of dead necrotic annexin V-negative, 7-AAD-positive leukocytes was significantly lower under the use of inhaled amikacin than at the beginning of treatment. Conclusions In this pilot study, we found that administration of aerosolized amikacin combined with the systemic antimicrobial therapy improves the clinical outcome of patients with VAP, effective early microbial decrease in the sputum, reduces reactive oxygen species generation in leukocytes and the degree of leukocyte apoptosis and necrosis, decreases VAP-mediated cell membrane alterations of circulating leukocytes.

Acid-tolerant bacteria and prospects in industrial and environmental applications

Acid-tolerant bacteria such as Streptococcus mutans, Acidobacterium capsulatum, Escherichia coli, and Propionibacterium acidipropionici have developed several survival mechanisms to sustain themselves in various acid stress conditions. Some bacteria survive by minor changes in the environmental pH. In contrast, few others adapt different acid tolerance mechanisms, including amino acid decarboxylase acid resistance systems, mainly glutamate-dependent acid resistance (GDAR) and arginine-dependent acid resistance (ADAR) systems. The cellular mechanisms of acid tolerance include cell membrane alteration in Acidithiobacillus thioxidans, proton elimination by F1-F0-ATPase in Streptococcus pyogenes, biofilm formation in Pseudomonas aeruginosa, cytoplasmic urease activity in Streptococcus mutans, synthesis of the protective cloud of ammonia, and protection or repair of macromolecules in Bacillus caldontenax. Apart from cellular mechanisms, there are several acid-tolerant genes such as gadA, gadB, adiA, adiC, cadA, cadB, cadC, speF, and potE that help the bacteria to tolerate the acidic environment. This acid tolerance behavior provides new and broad prospects for different industrial applications and the bioremediation of environmental pollutants. The development of engineered strains with acid-tolerant genes may improve the efficiency of the transgenic bacteria in the treatment of acidic industrial effluents. KEY POINTS: • Bacteria tolerate the acidic stress by methylating unsaturated phospholipid tail • The activity of decarboxylase systems for acid tolerance depends on pH • Genetic manipulation of acid-tolerant genes improves acid tolerance by the bacteria.

Abstract 3697: Modulation of Nicotinamide N-Methyl Transferase (NNMT) expression in TNBC is associated with altered cell membrane cholesterol levels

Abstract Introduction: Cancer cells often develop a program of metabolic adaptability and epigenetic remodelling to promote gene expression changes causing cancerous cell proliferation and invasion. The metabolic-epigenetic axis as a an underlying mechanism of carcinogenesis could lead to new approaches to cancer treatment. Nicotinamide N-Methyl Transferase (NNMT) is a metabolic enzyme that catalyzes the transfer of a methyl group from S-Adenosyl methionine (SAM) to nicotinamide, thereby decreasing the overall methyl pools for RNA, histone and DNA methylation. High NNMT expression has been previously associated with a poor outcome in TNBC. Hypothesis: We hypothesized that high versus low NNMT activity and resulting oncogenic gene expression in TNBC may alter histone methylation is association with altered metabolic pathway activation. Methods: We used two TNBC cell lines models, MDA-MB 231 and SUM159, to study the association between high versus low NNMT activity and metabolic pathway activation. Surprisingly, we identified gene expression pathways suggestive of increased free cholesterol biosynthesis gene expression with low NNMT, and then used biochemical assays and filipin to measure free cholesterol in both total high and low NNMT TNBC cell lysates and relative cholesterol expression in the High vs Low NNMT cell membranes. Results: In vitro, NNMT knockdown resulted in increased cholesterol synthetic pathway enzyme expression in both TNBC cell lines. In vivo studies also showed that protein expression of cholesterol synthesis enzymes was also increased in NNMT-depleted MDA-MB 231 xenografted tumors. Interestingly, the increased cholesterol level upon NNMT depletion was mainly localized at the plasma membrane via Filipin III staining, suggesting a possible association with less cellular membrane fluidity and a decreased oncogenic phenotype. In ongoing experiments, we are evaluating whether changes in histone methylation in high vs low NNMT cells are associated with differential expression of cholesterol biosynthetic genes, and free cholesterol production. We hypothesize that NNMT might epigenetically decrease the methylation of histones regulating cholesterol production in TNBC. Citation Format: Woei-Yaw Chee, Deniz Nesli Dolcen, Lynda Bennett, Suzanne D. Conzen. Modulation of Nicotinamide N-Methyl Transferase (NNMT) expression in TNBC is associated with altered cell membrane cholesterol levels. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3697.

Altered plasma membrane abundance of the sulfatide-binding protein NF155 links glycosphingolipid imbalances to demyelination

Myelin is a multilayered membrane that tightly wraps neuronal axons, enabling efficient, high-speed signal propagation. The axon and myelin sheath form tight contacts, mediated by specific plasma membrane proteins and lipids, and disruption of these contacts causes devastating demyelinating diseases. Using two cell-based models of demyelinating sphingolipidoses, we demonstrate that altered lipid metabolism changes the abundance of specific plasma membrane proteins. These altered membrane proteins have known roles in cell adhesion and signaling, with several implicated in neurological diseases. The cell surface abundance of the adhesion molecule neurofascin (NFASC), a protein critical for the maintenance of myelin-axon contacts, changes following disruption to sphingolipid metabolism. This provides a direct molecular link between altered lipid abundance and myelin stability. We show that the NFASC isoform NF155, but not NF186, interacts directly and specifically with the sphingolipid sulfatide via multiple binding sites and that this interaction requires the full-length extracellular domain of NF155. We demonstrate that NF155 adopts an S-shaped conformation and preferentially binds sulfatide-containing membranes in cis, with important implications for protein arrangement in the tight axon-myelin space. Our work links glycosphingolipid imbalances to disturbance of membrane protein abundance and demonstrates how this may be driven by direct protein-lipid interactions, providing a mechanistic framework to understand the pathogenesis of galactosphingolipidoses.

Prevention of Chilling Injury in Pomegranates Revisited: Pre- and Post-Harvest Factors, Mode of Actions, and Technologies Involved.

The storage life of pomegranate fruit (Punica granatum L.) is limited by decay, chilling injury, weight loss, and husk scald. In particular, chilling injury (CI) limits pomegranate long-term storage at chilling temperatures. CI manifests as skin browning that expands randomly with surface spots, albedo brown discoloration, and changes in aril colors from red to brown discoloration during handling or storage (6-8 weeks) at <5-7 °C. Since CI symptoms affect external and internal appearance, it significantly reduces pomegranate fruit marketability. Several postharvest treatments have been proposed to prevent CI, including atmospheric modifications (MA), heat treatments (HT), coatings, use of polyamines (PAs), salicylic acid (SA), jasmonates (JA), melatonin and glycine betaine (GB), among others. There is no complete understanding of the etiology and biochemistry of CI, however, a hypothetical model proposed herein indicates that oxidative stress plays a key role, which alters cell membrane functionality and integrity and alters protein/enzyme biosynthesis associated with chilling injury symptoms. This review discusses the hypothesized mechanism of CI based on recent research, its association to postharvest treatments, and their possible targets. It also indicates that the proposed mode of action model can be used to combine treatments in a hurdle synergistic or additive approach or as the basis for novel technological developments.

Pre-exposure to titanium or iron oxide nanoparticles suppresses the subsequent cellular uptake of gold nanoparticles

Humans are exposed to a wide variety of natural and engineered nanoparticles (NPs) during their lifetime. However, the effects of pre-exposure to NPs on subsequent uptake of other NPs have not been investigated. In the present study, we investigated the effects of pre-exposure to three NPs (TiO2, Fe2O3, and SiO2 NPs) on the subsequent uptake of gold NPs (AuNPs) by hepatocellular carcinoma cells (HepG2). When HepG2 cells were pre-exposed to TiO2 or Fe2O3 NPs, but not SiO2 NPs for 2 days, their subsequent uptake of AuNPs was inhibited. Such inhibition was also observed in human cervical cancer (HeLa) cells, suggesting that this phenomenon is present in different cell types. The mechanisms underlying the inhibitory effect of NP pre-exposure include altered plasma membrane fluidity due to changes in lipid metabolism and reduced intracellular ATP production due to decreased intracellular oxygen. Despite the inhibitory effects of NP pre-exposure, full recovery was observed after transferring the cells to medium without NPs, even when the pre-exposure time was extended from 2 days to 2 weeks. Overall, the pre-exposure effects observed in the present study should be considered in the biological application and risk evaluation of NPs.

Effects of Volatile Anesthetics versus Ketamine on Blood-Brain Barrier Permeability via Lipid-Mediated Alterations of Endothelial Cell Membranes.

The purpose of this study was to investigate the effects of the volatile anesthetic agents isoflurane and sevoflurane, at clinically relevant concentrations, on the fluidity of lipid membranes and permeability of the blood-brain barrier (BBB). We analyzed the in vitro effects of isoflurane or ketamine using erythrocyte ghosts (sodium fluorescein permeability), monolayers of brain microvascular endothelial cells ([13C]sucrose and fluorescein permeability), or liposomes (fluorescence anisotropy). Additionally, we determined the effects of 30-minute exposure of mice to isoflurane on the brain tight junction proteins. Finally, we investigated in vivo brain uptake of [13C]mannitol and [13C]sucrose after intravenous administration in mice under anesthesia with isoflurane, sevoflurane, or ketamine/xylazine in addition to the awake condition. Isoflurane at 1-mM and 5-mM concentrations increased fluorescein efflux from the erythrocyte ghosts in a concentration-dependent manner. Similarly, in endothelial cell monolayers exposed to 3% (v/v) isoflurane, permeability coefficients rose by about 25% for fluorescein and 40% for [13C]sucrose, whereas transendothelial resistance and cell viability remained unaffected. Although isoflurane caused a significant decrease in liposomes anisotropy values, ketamine/xylazine did not show any effects. Brain uptake clearance (apparent Kin) of the passive permeability markers in vivo in mice approximately doubled under isoflurane or sevoflurane anesthesia compared with either ketamine/xylazine anesthesia or the awake condition. In vivo exposure of mice to isoflurane did not change any of the brain tight junction proteins. Our data support membrane permeabilization rather than loosening of intercellular tight junctions as an underlying mechanism for increased permeability of the endothelial cell monolayers and the BBB in vivo. SIGNIFICANCE STATEMENT: The blood-brain barrier controls the entry of endogenous substances and xenobiotics from the circulation into the central nervous system. Volatile anesthetic agents like isoflurane alter the lipid structure of cell membranes, transiently facilitating the brain uptake of otherwise poorly permeable, hydrophilic small molecules. Clinical implications may arise when potentially neurotoxic drugs gain enhanced access to the central nervous system under inhalational anesthetics.

Nanoscale imaging of CD47 informs how plasma membrane modifications shape apoptotic cell recognition

CD47 recognized by its macrophage receptor SIRPα serves as a “don’t eat-me” signal protecting viable cells from phagocytosis. How this is abrogated by apoptosis-induced changes in the plasma membrane, concomitantly with exposure of phosphatidylserine and calreticulin “eat-me“ signals, is not well understood. Using STORM imaging and single-particle tracking, we interrogate how the distribution of these molecules on the cell surface correlates with plasma membrane alteration, SIRPα binding, and cell engulfment by macrophages. Apoptosis induces calreticulin clustering into blebs and CD47 mobility. Modulation of integrin affinity impacts CD47 mobility on the plasma membrane but not the SIRPα binding, whereas CD47/SIRPα interaction is suppressed by cholesterol destabilization. SIRPα no longer recognizes CD47 localized on apoptotic blebs. Overall, the data suggest that disorganization of the lipid bilayer at the plasma membrane, by inducing inaccessibility of CD47 possibly due to a conformational change, is central to the phagocytosis process.

Cerium Oxide/Graphene Oxide Hybrid: Synthesis, Characterization, and Evaluation of Anticancer Activity in a Breast Cancer Cell Line (MCF-7)

In the present study, we used a simple ultrasonic approach to develop a Cerium oxide/Graphene oxide hybrid (CeO2/GO hybrid) nanocomposite system. Particle size analysis, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) have been used to analyze the physio-chemical characteristics of the developed nanocomposite. The synthesized hybrid system has also been examined to assess its anticancer capability against MCF-7 cell lines and normal cell lines at different sample concentrations, pH values, and incubation intervals using an antiproliferative assay test. The test results demonstrate that as sample concentration rises, the apoptotic behavior of the CeO2/GO hybrid in the MCF-7 cell line also rises. The IC50 was 62.5 µg/mL after 72 h of incubation. Cytotoxicity of cisplatin bound CeO2/GO hybrid was also tested in MCF-7 cell lines. To identify apoptosis-associated alterations of cell membranes during the process of apoptosis, a dual acridine orange/ethidium bromide (AO/EB) fluorescence staining was carried out at three specified doses (i.e., 1000 µg/mL, 250 µg/mL, and 62.5 µg/mL of CeO2/GO hybrid). The color variations from both live (green) and dead (red) cells were examined using fluorescence microscopy under in vitro conditions. The quantitative analysis was performed using flow cytometry to identify the cell cycle at which the maximum number of MCF-7 cells had been destroyed as a result of interaction with the developed CeO2/GO hybrid (FACS study). According to the results of the FACS investigation, the majority of cancer cells were inhibited at the R3 (G2/M) phase. Therefore, the CeO2/GO hybrid has successfully showed enhanced anticancer efficacy against the MCF-7 cell line at the IC50 concentration. According to the current study, the CeO2/GO platform can be used as a therapeutic platform for breast cancer. The synergetic effects of the developed CeO2/GO hybrid with the MCF-7 cell line are presented.

The role of potassium current in the pulmonary response to environmental oxidative stress

Exposure of human lung epithelial cells (A549 cell line) to the oxidant pollutant ozone (O3) alters cell membrane currents inducing its decrease, when the cell undergoes to a voltage-clamp protocol ranging from −90 to +70mV. The membrane potential of these cells is mainly maintained by the interplay of potassium and chloride currents. Our previous studies indicated the ability of O3 to activate ORCC (Outward Rectifier Chloride Channel) and consequently increases the chloride current.In this paper our aim was to understand the response of potassium current to oxidative stress challenge and to identify the kind potassium channel involved in O3 induced current changes.After measuring the total membrane current using an intracellular solution with or without potassium ions, we obtained the contribution of potassium to the overall membrane current in control condition by a mathematical approach. Repeating these experiments after O3 treatment we observed a significant decrease of Ipotassium. Treatment of the cells with Iberiotoxin (IbTx), a specific inhibitor of BK channel, we were able to verify the presence and the functionality of BK channels. In addition, the administration of 4-Aminopyridine (an inhibitor of voltage dependent K channels but not BK channels) and Tetraethylammonium (TEA) before and after O3 treatment we observed the formation of BK oxidative post-translation modifications.Our data suggest that O3 is able to inhibit potassium current by targeting BK channel. Further studies are needed to better clarify the role of this BK channel and its interplay with the other membrane channels under oxidative stress conditions. These findings can contribute to identify the biomolecular pathway induced by O3 allowing a possible pharmacological intervention against oxidative stress damage in lung tissue.

Cannabidiol and cannabinol have distinct effects on membrane structure.

Despite widespread public use, relatively little is known about the compounds cannabidiol (CBD) and cannabinol (CBN), or their interactions with cellular targets. Produced by Cannabis sativa, CBD and CBN have similar chemical structures and are used both pharmaceutically and commercially/recreationally; the former is not psychoactive while the latter is mildly so. Previously CBD was shown to affect the organization of membrane lipids, which indirectly alters sodium channel function (Ghovanloo et al (2021) Cannabidiol inhibits the skeletal muscle Nav1.4 by blocking its pore and by altering membrane elasticity J Gen Physiol; 153 (5): e202012701). Here we use deuterium nuclear magnetic resonance (2H NMR) spectroscopy to investigate the effects of CBD and CBN on 1-palmitoyl-d31-2-oleoyl-sn-glycero-3-phosphocholine (POPC-d31) and POPC-d31/cholesterol multilamellar dispersions as a function of temperature. CBD and CBN affect POPC-d31 membrane organization in a similar way, with increased order in the region of the bilayer near the lipid-water interface and decreased order in the middle of the bilayer. However, CBD and CBN have markedly different effects when added to POPC-d31/cholesterol membranes. Both cannabinoids disorder POPC-d31 in the presence of cholesterol, but CBN's impact on lipid chain organization is significantly greater than that of CBD. These results add support to the theory that CBD and CBN can exert effects on membrane proteins indirectly by altering cell membrane physical properties.

Effects of an Endocrine Disruptor Triclosan on Ruditapes decussatus: Multimarker and Histological Approaches.

The aim of this work was to study the ecotoxicological effects of an endocrine disruptor triclosan on the clam Ruditapes decussatus. The bivalves were exposed to three concentrations of this biocide (C1 = 100 ng/L, C2 = 200 ng/L and C3 = 500 ng/L) for three and seven days. The impact was assessed at the gills and digestive glands, through activities of an antioxidant defense biomarker (Gluthatione S-Transferase, GST), a damage biomarker (Malondialdehyde, MDA), and a neurotoxicity biomarker (Acetylcholinesterase, AChE). Furthermore, histological traits were approached in different organs to evaluate any possible alteration induced by triclosan. It appears from this study that both gills and digestive glands responded discernibly to triclosan and effects were concentration-dependent. The stressed clams showed a significant increase in their GST and MDA activities in gills and digestive glands compared to controls for both time slots considered. In turn, the AChE activity was clearly inhibited in both organs in a time dependent way. The histological study made it possible to observe several structural pathologies caused by triclosan in the gills and the digestive gland. These alterations consisted mainly of inflammatory reactions, malformations of the lamellae and fusion of the gill filaments, degeneration of the connective tissue, and the erosion of the gill cilia with the appearance of certain severe alterations (cell necrosis and apoptosis), which can thus cause a malfunction of the gills and eventually lead to a reduction in oxygen consumption and a disruption of the osmoregulation for bivalves. Alterations in the digestive gland have also been detected, mainly by epithelial alterations, thinning of the tubules, and alteration of the basal cell membrane which can impair the ability of clams to absorb food. At germinal cells, several damages were observed in the oocytes which probably disturbed the reproductive function and the fertility of the clams. The damages observed in female gonads were caused by the cytolysis of a large number of oocytes through autophagy and necrosis at 200 ng triclosan/L. Moreover, at 500 ng triclosan/L, hemocytic infiltration was observed in acini and apoptotic bodies reflected in the fragmentation of more than 90% of oocytes.

Inactivation of Pseudomonas aeruginosa biofilms by thymoquinone in combination with nisin.

Pseudomonas aeruginosa is one of the most important foodborne pathogens that can persist in leafy green vegetables and subsequently produce biofilms. In this study, the synergistic effect of thymoquinone and nisin in reducing biofilm formation of P. aeruginosa on lettuce was evaluated, and their anti-virulence and anti-biofilm mechanisms were also investigated. At concentrations ranging from 0.5 to 2 mg/ml, thymoquinone inhibited the production of autoinducers and virulence factors, and enhanced the susceptibility of P. aeruginosa biofilms to nisin as evidenced by the scanning electron microscopy and confocal laser scanning microscopy. Integrated transcriptomics, metabolomics, and docking analyses indicated that thymoquinone treatment disrupted the quorum sensing (QS) system, altered cell membrane component, and down-regulated the expressions of genes related to virulence, efflux pump, and antioxidation. The changed membrane component and repressed efflux pump system enhanced membrane permeability and facilitated the entrance of nisin into cells, thus improving the susceptibility of biofilms to nisin. The dysfunctional QS and repressed antioxidant enzymes lead to the enhancement of oxidative stress. The enhanced oxidative stress disrupted energy metabolism and protein metabolism and ultimately attenuated the virulence and pathogenicity of P. aeruginosa PAO1. Our study indicated that thymoquinone has the potential to function as a QS-based agent to defend against foodborne pathogens in combination with nisin.

Dapagliflozin Treatment Augments Bioactive Phosphatidylethanolamine Concentrations in Kidney Cortex Membrane Fractions of Hypertensive Diabetic db/db Mice and Alters the Density of Lipid Rafts in Mouse Proximal Tubule Cells.

In addition to inhibiting renal glucose reabsorption and allowing for glucose excretion, the sodium/glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin may be efficacious in treating various comorbidities associated with type 2 diabetes mellitus (T2DM). The molecular mechanisms by which dapagliflozin exerts its beneficial effects are largely unknown. We hypothesized dapagliflozin treatment in the diabetic kidney alters plasma membrane lipid composition, suppresses extracellular vesicle (EV) release from kidney cells, and disrupts lipid rafts in proximal tubule cells. In order to test this hypothesis, we treated diabetic db/db mice with dapagliflozin (N = 8) or vehicle (N = 8) and performed mass spectrometry-based lipidomics to investigate changes in the concentrations of membrane lipids in the kidney cortex. In addition, we isolated urinary EVs (uEVs) from urine samples collected during the active phase and the inactive phase of the mice and then probed for changes in membrane proteins enriched in the EVs. Multiple triacylglycerols (TAGs) were enriched in the kidney cortex membrane fractions of vehicle-treated diabetic db/db mice, while the levels of multiple phosphatidylethanolamines were significantly higher in similar mice treated with dapagliflozin. EV concentration and size were lesser in the urine samples collected during the inactive phase of dapagliflozin-treated diabetic mice. In cultured mouse proximal tubule cells treated with dapagliflozin, the lipid raft protein caveolin-1 shifted from less dense fractions to more dense sucrose density gradient fractions. Taken together, these results suggest dapagliflozin may regulate lipid-mediated signal transduction in the diabetic kidney.