Differential gene expression of the nosocomial pathogen Enterococcus faecalis subjected to metal stress
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ABSTRACT:
ORGANISM(S): Enterococcus faecalis
PROVIDER: GSE79250 | GEO | 2016/03/16
SECONDARY ACCESSION(S): PRJNA315283
REPOSITORIES: GEO
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Project description:Emerging antibiotic resistance among clinically relevant bacteria, paired with their ability to form biofilms on medical and technical devices, represents a serious problem in terms of effective and long-term decontamination in health care environments and gives rise to an urgent need for new antimicrobial materials. Here we present the first study of the impact of AGXX®, a novel broad-spectrum antimicrobial surface coating consisting of micro galvanic elements formed by silver and ruthenium, on the transcriptome of the nosocomial pathogen Enterococcus faecalis. E. faecalis was subjected to metal stress by growing it for different periods of time in the presence of AGXX® or silver-coated steel meshes. Subsequently, total RNA was isolated and next-generation RNA sequencing was performed to analyze variations in gene expression levels in the presence of the antimicrobial materials with focus on known stress genes. Exposure to AGXX® had a large impact on the transcriptome of E. faecalis. After 24 minutes almost 1/5 of the E. faecalis genome displayed differential expression. At each time-point the cop operon was strongly up-regulated, providing indirect evidence for the presence of free Ag+-ions. Moreover, exposure to AGXX® induced a broad general stress response in E. faecalis. Genes coding for the chaperones GroEL and GroES as well as the Clp proteases ClpE and ClpB were among the top up-regulated heat shock genes. Furthermore, differential expression of genes coding for thioredoxin, superoxide dismutase and glutathione synthetase indicates a high level of oxidative stress. We postulate a mechanism of action where the combination of Ag+-ions and reactive oxygen species generated by AGXX® results in a synergistic antimicrobial effect, which is superior to that of conventional silver coatings. Gene expression analysis of Enterococcus faecalis 12030 either subjected to metal stress by exposure to an antimicrobial AGXX®- or Ag-coated V2A steel mesh or exposed to an uncoated V2A steel mesh or left untreated performing RNA Sequencing with an Ion ProtonTM Sequencer and subsequent data analysis with a T-REx RNA-Sequencing expression analysis pipeline.
2016-03-16 | E-GEOD-79250 | biostudies-arrayexpress
Project description:Permanent synthetic meshes are a prized option to promote soft-tissue support and repair in several surgical procedures. Contrariwise, the risk to develop biomaterial-associated infection (BAI) has not been solved. Intrinsically antibacterial materials, such as those that include metals with antimicrobial activity as part of their composition, are an advanced approach to be further explored for BAI prevention. In this study, a panel of in vitro, ex vivo and in vivo assays was used to compare a novel polypropylene-based surgical mesh modified with silver-containing microparticles with a commercially available similar device normally used for hernia repair. To comprehensively identify specific mechanisms of how the new silver-containing meshes influence the full host-tissue response in the presence and absence of infection, prostheses were screened for cytotoxicity, biological integration and transcriptomic responses, and additional antibiofilm production behaviour. Silver-modified polypropylene meshes exhibited good properties in terms of mechanical and cytotoxic values, as well as a modest prevention of biofilm formation. Moreover, they promoted connective tissue deposition and angiogenesis and, outstandingly, induced “immunomodulating” effects that may be potentially useful in the clinical context. Overall, the results substantiate the potential use of polypropylene surgical meshes modified with silver-containing microparticles as a means to prevent BAI in soft tissue repair.
2016-10-03 | GSE85139 | GEO
Project description:The current study deals to decipher the antibacterial mechanism of lysozyme coated silver nanoparticles (L-Ag NPs) (coated with lysozyme) against a Gram negative modal organism Escherichia coli K12 (MTCC 1302). Hence, the whole transcriptome profiling of E. coli K12 was done by exposing it to the MIC75 concentration of L-Ag NPs for 5 and 30 min., by RNA sequencing (RNAseq) analysis. The obtained results were utilized to understand all the metabolic pathways, signaling and molecular functions in bacterial cells under the stress of L-Ag NPs. RNAseq showed a high number of total reads along with significant ratio of high-quality reads, which confirmed the excellent quality and quantity of the obtained RNAseq data. Controlled release of ions from the surface of L-Ag NPs allowed the bacterial cells to function normally till the accumulation of threshold amount of silver ions which triggered the action of defence system, thus, reducing the chances of resistance development in bacteria. In long term, such treatment may force the bacterial machinery to induce changes in their genome to counteract the situation and develop resistance against silver ions, similar to the well-known antibiotic resistance problem. The obtained results advocate that L-Ag NPs can be used as effective antibacterial agent.
2022-06-15 | GSE151954 | GEO
Project description:Infections associated with antimicrobial-resistant bacteria now represent a significant threat to human health using conventional therapy, necessitating the development of alternate and more effective antibacterial compounds. Silver nanoparticles (Ag NPs) have been proposed as potential antimicrobial agents to combat infections. A complete understanding of their antimicrobial activity is required before these molecules can be used in therapy. Lysozyme coated Ag NPs were synthesized and characterized by TEMEDS, XRD, UV-vis, FTIR spectroscopy, zeta potential, and oxidative potential assay. Biochemical assays and deep level transcriptional analysis using RNA sequencing were used to decipher how Ag NPs exert their antibacterial action against multi-drug resistant Klebsiella pneumoniae MGH78578. RNAseq data revealed that Ag NPs induced a triclosan-like bactericidal mechanism responsible for the inhibition of the type II fatty acid biosynthesis. Additionally, released AgC generated oxidative stress both extra and intracellularly in K. pneumoniae. The data showed that triclosan-like activity and oxidative stress cumulatively underpinned the antibacterial activity of Ag NPs. This result was confirmed by the analysis of the bactericidal effect of Ag NPs against the isogenic K. pneumoniae MGH78578 1soxS mutant, which exhibits a compromised oxidative stress response compared to the wild type. Silver nanoparticles induce a triclosan like antibacterial action mechanism in multi-drug resistant K. pneumoniae. This study extends our understanding of anti-Klebsiella mechanisms associated with exposure to Ag NPs. This allowed us to model how bacteria might develop resistance against silver nanoparticles, should the latter be used in therapy.
2021-01-31 | GSE151953 | GEO
Project description:The release of silver nanoparticles (SNPs) in the environment has raised concerns about their effects on living organisms, including plants. In this study, changes in gene expression in Arabidopsis thaliana exposed to SNPs and silver ions (Ag+) were analyzed using Affymetrix expression microarrays. Exposure to 5 mg SNPs L-1 (20 nm) for 10 days resulted in up-regulation of 286 genes and down-regulation of 81 genes by reference to non-exposed plants. Exposure to 5 mg Ag+ L-1 for 10 days resulted in up-regulation of 84 genes and down-regulation of 53 genes by reference to non-exposed plants. Many genes differentially expressed by SNPs and Ag+ were found to be involved in plant response to various stresses: up-regulated genes were primarily associated with response to metals and oxidative stress (e.g., vacuolar cation/proton exchanger, superoxide dismutase, cytochrome P-450-dependent oxidase, and peroxidase), while down-regulated genes were more associated with response to pathogens and hormonal stimuli (e.g., auxin-regulated gene involved in organ size (ARGOS), ethylene signaling pathway, and systemic acquired resistance (SAR) against fungi and bacteria). A significant overlap was observed between genes differentially expressed in response to SNPs and Ag+ (13% and 21% of total up- and down-regulated genes, respectively), suggesting that SNP-induced stress originates partly from silver toxicity and partly from nanoparticle-specific effects. Three highly up-regulated genes in the presence of SNPs, but not Ag+, belong to the thalianol biosynthetic pathway, which is thought to be involved in plant defense system. Results from this study provide insights into the molecular mechanisms of plant response to SNPs and Ag+.
2014-02-12 | E-MEXP-3950 | biostudies-arrayexpress
Project description:Effects of silver nanoparticles (Ag NPs) on freshwater species have been reported in several studies, but there is not information on the potential long-term consequences of a previous exposure. In this work, we investigated the long-term effects of maltose-coated Ag NPs (20 nm) and of ionic silver (10 µg/L) after 21 days of exposure and at 6 months post-exposure (mpe) in adult zebrafish. Exposure resulted in significant silver accumulation in the whole body of fish exposed to ionic silver, but not in those exposed to Ag NPs. However, autometallography revealed metal accumulation in the liver and intestine of fish treated with the two silver forms and especially in the intestine of fish exposed to Ag NPs. X-ray microanalysis showed the presence of silver in gills, liver and intestine and of Ag NPs in gill and liver cells. Inflammation and hyperplasia were evident in the gills after both treatments and these histopathological conditions remained at 6 mpe. According to the hepatic transcriptome analysis, at 3 days ionic silver regulated a larger number of transcripts (410) than Ag NPs (129), while at 21 days Ag NPs provoked a stronger effect (799 vs 165 regulated sequences). Gene ontology terms such as “metabolic processes” and “response to stimulus” appeared enriched after all treatments, while “immune system” or “reproductive processes” were specifically enriched after the exposure to Ag NPs. This suggests that the toxicity of Ag NPs may not be solely related to the release of Ag ions, but also to the NP form. No evident effects were found on protein oxidation or on hepatocyte lysosomal membrane stability during exposure, but effects recorded on liver lysosomes and persistent damage on gill tissue at 6 mpe could indicate potential for long-term effects in exposed fish.
2018-06-12 | GSE89653 | GEO
Project description:The rapid emergence of drug resistant Staphylococcus aureus (S. aureus), in particular, methicillin-resistant S. aureus (MRSA) poses a serious threat to public health globally. Reuse of metal-based antimicrobials stands for one of the most promising strategies to resensitize drug resistant bacteria to conventional antibiotics. Silver (Ag) has been used as an antimicrobial agent since antiquity, yet its molecular mechanism of action is elusive largely owing to technical challenges to identify the direct silver-binding protein targets accountable for its action. Herein, using an in-house developed hyphenated technique LC-GE-ICP-MS, we successfully separated and identified 38 authentic Ag+-binding proteins (Ag+-proteome) in S. aureus at the whole-cell scale for the first time. By integration with bioinformatic analysis and systematic biochemical characterizations, we captured the first snapshot on the dynamic action of Ag+ against S. aureus at the molecular level, i.e., Ag+ primarily targets glycolysis via inhibiting multiple enzymes and induces the elevation of ROS through functional disruption of redox homeostasis system at the late stage, leading to an upregulation of oxidative pentose phosphate pathway (oxPPP) to alleviate Ag+ stress. However, the activation of oxPPP is ultimately futile due to key oxPPP enzymes being inhibited by Ag+. We further validated that Ag+ could inhibit 6-phosphogluconate dehydrogenase, a key target from oxPPP through binding to His185 at the active site and morphing the shape of catalytic pocket by X-ray crystallography. Significantly, the multi-target mode of action of silver is accountable for its suppression of antibiotic selection effects towards S. aureus as well as its sustainable antimicrobial activity. Such a unique mode of action of Ag+ (and silver nanoparticles) led to enhanced efficacy of a broad range of antibiotics and resensitization of MRSA to antibiotics. Our study resolves the long-standing question of the molecular targets of silver in S. aureus and offers a novel insight into the sustainable bacterial susceptibility of silver, providing a potential approach for combating antimicrobial resistance.
2021-09-10 | PXD025106 | Pride
Project description:Silver nanoparticles are used in consumer products like food contact materials, drinking water technologies and supplements, due to their antimicrobial properties. This leads to an oral uptake and exposure of intestinal cells. In contrast to other studies we found no apoptosis induction by surfactant coated silver nanoparticles in the intestinal cell model Caco-2 in a previous study, although the particles induced oxidative stress, morphological changes and cell death. Therefore, this study aimed to analyze the molecular mechanism of silver nanoparticles in Caco-2 cells. We used global gene expression profiling in differentiated Caco-2 cells, supported by verification of the microarray data by quantitative real time RT-PCR and microscopic analysis, impedance measurements and assays for apoptosis and oxidative stress. Our results revealed that the majority of surfactant coated silver nanoparticles are not taken up into differentiated Caco-2 cells. and probably affect the cells by outside-in signaling. They induce oxidative stress and have an influence on canonical pathways related to FAK, ILK, ERK, MAPK, integrins and adherence and tight junctions, thereby inducing transcription factors like AP1, NFĸB and NRF2, which mediate cellular reactions in response to oxidative stress and metal ions and induce changes in the cytoskeleton and cell-cell and cell-matrix contacts. The present data confirm the absence of apoptotic cell death. Non-apoptotic, necrotic cell death, especially in the intestine, can cause inflammation and influence the mucosal immune response.
2015-11-13 | GSE62253 | GEO
Project description:Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physicochemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within 1 h following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating, and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology, and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna. Four replicates each of five toxicant exposure groups of ~20 animals and four replicates of control, unexposed animals. Each control was compared to each exposed data set for a total of 16 comparisons per chemical condition.
2013-12-31 | E-GEOD-47064 | biostudies-arrayexpress
Project description:Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physicochemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within 1 h following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating, and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology, and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna.
2013-12-31 | GSE47064 | GEO