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1.
PLoS One ; 19(7): e0306998, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38985791

RESUMO

Infectious and foodborne diseases pose significant global threats, with devastating consequences in low- and middle-income countries. Ozone, derived from atmospheric oxygen, exerts antimicrobial effects against various microorganisms, and degrades fungal toxins, which were initially recognized in the healthcare and food industries. However, highly concentrated ozone gas can be detrimental to human health. In addition, ozonated water is unstable and has a short half-life. Therefore, ultrafine-bubble technology is expected to overcome these issues. Ultrafine bubbles, which are nanoscale entitles that exist in water for considerable durations, have previously demonstrated bactericidal effects against various bacterial species, including antibiotic-resistant strains. This present study investigated the effects of ozone ultrafine bubble water (OUFBW) on various bacterial toxins. This study revealed that OUFBW treatment abolished the toxicity of pneumolysin, a pneumococcal pore-forming toxin, and leukotoxin, a toxin that causes leukocyte injury. Silver staining confirmed the degradation of pneumolysin, leukotoxin, and staphylococcal enterotoxin A, which are potent gastrointestinal toxins, following OUFB treatment. In addition, OUFBW treatment significantly inhibited NF-κB activation by Pam3CSK4, a synthetic triacylated lipopeptide that activates Toll-like receptor 2. Additionally, OUFBW exerted bactericidal activity against Staphylococcus aureus, including an antibiotic-resistant strain, without displaying significant toxicity toward human neutrophils or erythrocytes. These results suggest that OUFBW not only sterilizes bacteria but also degrades bacterial toxins.


Assuntos
Toxinas Bacterianas , Ozônio , Ozônio/química , Ozônio/farmacologia , Humanos , Toxinas Bacterianas/metabolismo , Água/química , NF-kappa B/metabolismo , Proteínas de Bactérias/metabolismo
2.
Subcell Biochem ; 104: 245-267, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38963490

RESUMO

Bacteria encode a wide range of survival and immunity systems, including CRISPR-Cas, restriction-modification systems, and toxin-antitoxin systems involved in defence against bacteriophages, as well as survival during challenging growth conditions or exposure to antibiotics. Toxin-antitoxin (TA) systems are small two- or three-gene cassettes consisting of a metabolic regulator (the "toxin") and its associated antidote (the "antitoxin"), which also often functions as a transcriptional regulator. TA systems are widespread in the genomes of pathogens but are also present in commensal bacterial species and on plasmids. For mobile elements such as plasmids, TA systems play a role in maintenance, and increasing evidence now points to roles of chromosomal toxin-antitoxin systems in anti-phage defence. Moreover, the widespread occurrence of toxin-antitoxin systems in the genomes of pathogens has been suggested to relate to survival during host infection as well as in persistence during antibiotic treatment. Upon repeated exposure to antibiotics, TA systems have been shown to acquire point mutations as well as more dramatic rearrangements such as in-frame deletions with potential relevance for bacterial survival and pathogenesis. In this review, we present an overview of the known functional and structural consequences of mutations and rearrangements arising in bacterial toxin-antitoxin systems and discuss their relevance for survival and persistence of pathogenic species.


Assuntos
Bactérias , Sistemas Toxina-Antitoxina , Sistemas Toxina-Antitoxina/genética , Bactérias/genética , Bactérias/metabolismo , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo
3.
Vet Microbiol ; 295: 110168, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38964035

RESUMO

Glaesserella parasuis is an important porcine pathogen that commonly colonizes the upper respiratory tract of pigs and is prone to causing Glässer's disease under complex conditions. As yet, the disease has led to serious economic losses to the swine industry worldwide. Studies so far have found that several virulence factors are associated with the pathogenicity of G. parasuis, but the pathogenic mechanism is still not fully understood. Cytolethal distending toxin (CDT), a potential virulence factor in G. parasuis, is involved in cytotoxicity, serum resistance, adherence to and invasion of host cells in vitro. Here, to further investigate the pathogenic role of CDT during G. parasuis infection in vitro and in vivo, a double cdt1 and cdt2 deletion mutant (Δcdt1Δcdt2) without selectable marker was first generated in G. parasuis JS0135 strain by continuous natural transformations and replica plating. Morphological observation and lactate dehydrogenase assay showed that the Δcdt1Δcdt2 mutant was defective in cytotoxicity. Additionally, the Δcdt1Δcdt2 mutant was more susceptible to phagocytosis caused by 3D4/2 macrophages compared to the wild-type JS0135 strain. Moreover, by focusing on clinical signs, necropsy, bacterial recovery and pathological observation, we found that the deletion of cdt1 and cdt2 genes led to a significant attenuation of virulence in G. parasuis. Taken together, these findings suggest that as an important virulence factor, CDT can significantly affect the pathogenicity of G. parasuis.


Assuntos
Toxinas Bacterianas , Haemophilus parasuis , Fagocitose , Doenças dos Suínos , Animais , Suínos , Haemophilus parasuis/patogenicidade , Haemophilus parasuis/genética , Toxinas Bacterianas/genética , Toxinas Bacterianas/toxicidade , Toxinas Bacterianas/metabolismo , Doenças dos Suínos/microbiologia , Virulência , Infecções por Haemophilus/veterinária , Infecções por Haemophilus/microbiologia , Infecções por Haemophilus/imunologia , Fatores de Virulência/genética , Macrófagos/microbiologia , Linhagem Celular
4.
World J Microbiol Biotechnol ; 40(9): 265, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38990361

RESUMO

The increasing prevalence of infections related to methicillin-resistant Staphylococcus aureus (MRSA) necessitates the exploration of innovative therapeutic strategies that diverge from conventional antibiotic treatments. This is imperative to effectively combat resistance and manage these infections. The adoption of antivirulence strategies has emerged as a particularly promising avenue. This approach applies a heightened selective pressure on pathogens, thereby diminishing the likelihood of bacteria evolving resistance to antibiotics. In our pursuit of novel therapeutics for treating MRSA infections, we have focused on agents that inhibit the virulence of S. aureus without impeding its growth, aiming to minimize the development of drug resistance. α-Hemolysin, a critical virulence factor encoded by the hla gene, is a cytotoxin that forms pores in host cell membranes and plays a pivotal role in the progression of disease during bacterial infections. Herein, we identified that norwogonin could effectively inhibit Hla production via targeting agrAC, a crucial protein in quorum sensing, resulting in dose-dependent inhibition of hemolytic activity without suppressing S. aureus growth. In vitro assays illustrated that norwogonin decreased the thermal stability of agrAC, providing evidence of interaction between norwogonin and agrAC. Meanwhile, norwogonin alleviated Hla-mediated A549 cell damage and reduced lactate dehydrogenase release. In vivo studies suggested that norwogonin treatment blocked the establishment of a mouse model of pneumonia caused by S. aureus USA300. Notably, norwogonin enhanced the antibacterial potency of oxacillin. In conclusion, norwogonin is a promising candidate for treating S. aureus infections, offering a novel alternative to traditional antibiotics by targeting virulence factors and enhancing the efficacy of existing treatments.


Assuntos
Antibacterianos , Proteínas de Bactérias , Proteínas Hemolisinas , Staphylococcus aureus Resistente à Meticilina , Fatores de Virulência , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Proteínas Hemolisinas/metabolismo , Animais , Camundongos , Humanos , Antibacterianos/farmacologia , Fatores de Virulência/metabolismo , Células A549 , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Virulência/efeitos dos fármacos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Modelos Animais de Doenças , Toxinas Bacterianas/metabolismo , Percepção de Quorum/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Feminino
5.
Arch Microbiol ; 206(8): 348, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38990418

RESUMO

Anatoxin-a (ATX-a) is a neurotoxin produced by some species of cyanobacteria. Due to its water solubility and stability in natural water, it could pose health risks to human, animals, and plants. Conventional water treatment techniques are not only insufficient for the removal of ATX-a, but they also result in cell lysis and toxin release. The elimination of this toxin through biodegradation may be a promising strategy. This study examines for the first time the biodegradation of ATX-a to a non-toxic metabolite (Epoxy-ATX-a) by a strain of Bacillus that has a history of dealing with toxic cyanobacteria in a eutrophic lake. The Bacillus strain AMRI-03 thrived without lag phase in a lake water containing ATX-a. The strain displayed fast degradation of ATX-a, depending on initial toxin concentration. At the highest initial concentrations (50 & 100 µg L- 1), total ATX-a degradation took place in 4 days, but it took 6 & 7 days at lower concentrations (20, 10, and 1 µg L- 1, respectively). The ATX-a biodegradation rate was also influenced by the initial toxin concentration, reaching its maximum value (12.5 µg L- 1 day- 1) at the highest initial toxin concentrations (50 & 100 µg L- 1). Temperature and pH also had an impact on the rate of ATX-a biodegradation, with the highest rates occurring at 25 and 30 ºC and pH 7 and 8. This nontoxic bacterial strain could be immobilized within a biofilm on sand filters and/or sludge for the degradation and removal of ATX-a and other cyanotoxins during water treatment processes, following the establishment of mesocosm experiments to assess the potential effects of this bacterium on water quality.


Assuntos
Bacillus subtilis , Biodegradação Ambiental , Toxinas de Cianobactérias , Cianobactérias , Eutrofização , Lagos , Tropanos , Lagos/microbiologia , Tropanos/metabolismo , Cianobactérias/metabolismo , Cianobactérias/isolamento & purificação , Bacillus subtilis/metabolismo , Bacillus subtilis/isolamento & purificação , Bacillus subtilis/genética , Arábia Saudita , Toxinas Bacterianas/metabolismo
6.
FASEB J ; 38(13): e23759, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38949635

RESUMO

The epidermal growth factor receptor (EGFR) is an important target for cancer therapies. Many head and neck cancer (HNC) cells have been reported to overexpress EGFR; therefore, anti-EGFR therapies have been attempted in patients with HNC. However, its clinical efficacy is limited owing to the development of drug resistance. In this study, we developed an EGFR-targeting immunotoxin consisting of a clinically proven anti-EGFR IgG (cetuximab; CTX) and a toxin fragment (LR-LO10) derived from Pseudomonas exotoxin A (PE) using a novel site-specific conjugation technology (peptide-directed photo-crosslinking reaction), as an alternative option. The immunotoxin (CTX-LR-LO10) showed specific binding to EGFR and properties of a typical IgG, such as stability, interactions with receptors of immune cells, and pharmacokinetics, and inhibited protein synthesis via modification of elongation factor-2. Treatment of EGFR-positive HNC cells with the immunotoxin resulted in apoptotic cell death and the inhibition of cell migration and invasion. The efficacy of CTX-LR-LO10 was evaluated in xenograft mouse models, and the immunotoxin exhibited much stronger tumor suppression than CTX or LR-LO10. Transcriptome analyses revealed that the immunotoxins elicited immune responses and altered the expression of genes related to its mechanisms of action. These results support the notion that CTX-LR-LO10 may serve as a new therapeutic agent targeting EGFR-positive cancers.


Assuntos
ADP Ribose Transferases , Receptores ErbB , Exotoxinas , Neoplasias de Cabeça e Pescoço , Imunoglobulina G , Imunotoxinas , Exotoxina A de Pseudomonas aeruginosa , Fatores de Virulência , Humanos , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/metabolismo , Receptores ErbB/imunologia , Animais , Imunotoxinas/farmacologia , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/imunologia , Neoplasias de Cabeça e Pescoço/metabolismo , Camundongos , Imunoglobulina G/farmacologia , Linhagem Celular Tumoral , Exotoxinas/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto , Cetuximab/farmacologia , Camundongos Nus , Toxinas Bacterianas , Apoptose/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Feminino , Movimento Celular/efeitos dos fármacos , Antineoplásicos/farmacologia
7.
Korean J Intern Med ; 39(4): 659-667, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38986495

RESUMO

BACKGROUND/AIMS: Sensitization to staphylococcal superantigens (SAgs) could contribute to asthma severity. However, its relevance with eosinophilic phenotype has not yet been clarified. This study aimed to investigate associations between serum specific IgE levels to SAg and eosinophilic airway inflammation in adult asthmatics. METHODS: The serum specific IgE levels to 3 SAgs, including staphylococcal enterotoxin A (SEA) and B (SEB), and toxic shock syndrome toxin-1 (TSST-1) were measured by ImmunoCAP in 230 adult asthmatic patients and 50 healthy controls (HCs). Clinical characteristics and laboratory parameters, including serum total/free IgE, and 2 eosinophil-activation markers, eosinophil cationic protein (ECP), and eosinophil-derived neurotoxin (EDN), were analyzed according to blood eosinophil counts (BEC; 150 cells/µL) and serum specific IgE levels to 3 SAgs (0.35 kU/L). RESULTS: Asthmatic patients showed higher serum specific IgE levels to 3 SAgs than HCs (p < 0.05 for all). The serum total/clinfree IgE levels were significantly higher in asthmatics with positive IgE responses to 3 SAgs than those without (p < 0.05 for all). There were no significant differences in clinical parameters including age, asthma severity, comorbidities, or smoking according to IgE responses to 3 SAgs. Patients with positive IgE responses to SEB (not to SEA/TSST-1) had higher serum specific IgE levels to house dust mites and ECP/EDN as well as higher BEC with positive correlations between serum SEB-specific IgE levels and BEC/ECP/EDN (p < 0.05 for all). CONCLUSION: These findings suggest that serum SEB-specific IgE levels could contribute to eosinophil activation as well as IgE production in adult asthma.


Assuntos
Asma , Enterotoxinas , Eosinófilos , Imunoglobulina E , Fenótipo , Superantígenos , Humanos , Enterotoxinas/imunologia , Imunoglobulina E/sangue , Masculino , Asma/imunologia , Asma/sangue , Asma/diagnóstico , Feminino , Pessoa de Meia-Idade , Adulto , Eosinófilos/imunologia , Estudos de Casos e Controles , Superantígenos/imunologia , Superantígenos/sangue , Biomarcadores/sangue , Idoso , Eosinofilia/imunologia , Eosinofilia/sangue , Eosinofilia/diagnóstico , Proteína Catiônica de Eosinófilo/sangue , Toxinas Bacterianas/imunologia , Toxinas Bacterianas/sangue , Neurotoxina Derivada de Eosinófilo/sangue
8.
Commun Biol ; 7(1): 839, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38987278

RESUMO

Clostridioides difficile causes a wide range of intestinal diseases through the action of two main cytotoxins, TcdA and TcdB. Ingested spores germinate in the intestine establishing a population of cells that produce toxins and spores. The pathogenicity locus, PaLoc, comprises several genes, including those coding for TcdA/B, for the holin-like TcdE protein, and for TcdR, an auto-regulatory RNA polymerase sigma factor essential for tcdA/B and tcdE expression. Here we show that tcdR, tcdA, tcdB and tcdE are expressed in a fraction of the sporulating cells, in either the whole sporangium or in the forespore. The whole sporangium pattern is due to protracted expression initiated in vegetative cells by σD, which primes the TcdR auto-regulatory loop. In contrast, the forespore-specific regulatory proteins σG and SpoVT control TcdR production and tcdA/tcdB and tcdE expression in this cell. We detected TcdA at the spore surface, and we show that wild type and ΔtcdA or ΔtcdB spores but not ΔtcdR or ΔtcdA/ΔtcdB spores are cytopathic against HT29 and Vero cells, indicating that spores may serve as toxin-delivery vehicles. Since the addition of TcdA and TcdB enhance binding of spores to epithelial cells, this effect may occur independently of toxin production by vegetative cells.


Assuntos
Toxinas Bacterianas , Clostridioides difficile , Esporos Bacterianos , Esporos Bacterianos/metabolismo , Esporos Bacterianos/genética , Clostridioides difficile/genética , Clostridioides difficile/metabolismo , Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/genética , Humanos , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Animais , Chlorocebus aethiops , Células Vero , Enterotoxinas/metabolismo , Enterotoxinas/genética
9.
Nat Commun ; 15(1): 5467, 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38937463

RESUMO

The genome of Mycobacterium tuberculosis encodes for a large repertoire of toxin-antitoxin systems. In the present study, MenT3 and MenT4 toxins belonging to MenAT subfamily of TA systems have been functionally characterized. We demonstrate that ectopic expression of these toxins inhibits bacterial growth and this is rescued upon co-expression of their cognate antitoxins. Here, we show that simultaneous deletion of menT3 and menT4 results in enhanced susceptibility of M. tuberculosis upon exposure to oxidative stress and attenuated growth in guinea pigs and mice. We observed reduced expression of transcripts encoding for proteins that are essential or required for intracellular growth in mid-log phase cultures of ΔmenT4ΔT3 compared to parental strain. Further, the transcript levels of proteins involved in efficient bacterial clearance were increased in lung tissues of ΔmenT4ΔT3 infected mice relative to parental strain infected mice. We show that immunization of mice and guinea pigs with ΔmenT4ΔT3 confers significant protection against M. tuberculosis infection. Remarkably, immunization of mice with ΔmenT4ΔT3 results in increased antigen-specific TH1 bias and activated memory T cell response. We conclude that MenT3 and MenT4 are important for M. tuberculosis pathogenicity and strains lacking menT3 and menT4 have the potential to be explored further as vaccine candidates.


Assuntos
Proteínas de Bactérias , Mycobacterium tuberculosis , Tuberculose , Animais , Cobaias , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/imunologia , Camundongos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/imunologia , Tuberculose/prevenção & controle , Tuberculose/imunologia , Tuberculose/microbiologia , Feminino , Pulmão/microbiologia , Pulmão/patologia , Pulmão/imunologia , Deleção de Genes , Toxinas Bacterianas/genética , Toxinas Bacterianas/imunologia , Toxinas Bacterianas/metabolismo , Camundongos Endogâmicos C57BL , Vacinas contra a Tuberculose/imunologia , Estresse Oxidativo , Virulência/genética
10.
Proc Natl Acad Sci U S A ; 121(25): e2316143121, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38861595

RESUMO

Vibrio vulnificus causes life-threatening wound and gastrointestinal infections, mediated primarily by the production of a Multifunctional-Autoprocessing Repeats-In-Toxin (MARTX) toxin. The most commonly present MARTX effector domain, the Makes Caterpillars Floppy-like (MCF) toxin, is a cysteine protease stimulated by host adenosine diphosphate (ADP) ribosylation factors (ARFs) to autoprocess. Here, we show processed MCF then binds and cleaves host Ras-related proteins in brain (Rab) guanosine triphosphatases within their C-terminal tails resulting in Rab degradation. We demonstrate MCF binds Rabs at the same interface occupied by ARFs. Moreover, we show MCF preferentially binds to ARF1 prior to autoprocessing and is active to cleave Rabs only subsequent to autoprocessing. We then use structure prediction algorithms to demonstrate that structural composition, rather than sequence, determines Rab target specificity. We further determine a crystal structure of aMCF as a swapped dimer, revealing an alternative conformation we suggest represents the open, activated state of MCF with reorganized active site residues. The cleavage of Rabs results in Rab1B dispersal within cells and loss of Rab1B density in the intestinal tissue of infected mice. Collectively, our work describes an extracellular bacterial mechanism whereby MCF is activated by ARFs and subsequently induces the degradation of another small host guanosine triphosphatase (GTPase), Rabs, to drive organelle damage, cell death, and promote pathogenesis of these rapidly fatal infections.


Assuntos
Toxinas Bacterianas , Vibrio vulnificus , Proteínas rab de Ligação ao GTP , Animais , Feminino , Humanos , Camundongos , Fatores de Ribosilação do ADP/metabolismo , Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/química , Células HEK293 , Camundongos Endogâmicos ICR , Proteólise , Proteínas rab de Ligação ao GTP/metabolismo , Vibrioses/microbiologia , Vibrioses/metabolismo , Vibrio vulnificus/metabolismo , Vibrio vulnificus/patogenicidade
11.
Microbiologyopen ; 13(3): e23, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38867416

RESUMO

The G protein-coupled estrogen receptor, also known as GPER1 or originally GPR30, is found in various tissues, indicating its diverse functions. It is typically present in immune cells, suggesting its role in regulating immune responses to infectious diseases. Our previous studies have shown that G-1, a selective GPER agonist, can limit the pathogenesis mediated by Staphylococcus aureus alpha-hemolysin (Hla). It aids in clearing bacteria in a mouse skin infection model and restricts the surface display of the Hla receptor, ADAM10 (a disintegrin and metalloprotease 10) in HaCaT keratinocytes. In this report, we delve into the modulation of GPER in human immune cells in relation to the NLRP3 inflammasome. We used macrophage-like differentiated THP-1 cells for our study. We found that treating these cells with G-1 reduces ATP release, decreases the activity of the caspase-1 enzyme, and lessens cell death following Hla intoxication. This is likely due to the reduced levels of ADAM10 and NLRP3 proteins, as well as the decreased display of the ADAM10 receptor in the G-1-treated THP-1 cells. Our studies, along with our previous work, suggest the potential therapeutic use of G-1 in reducing Hla susceptibility in humans. This highlights the importance of GPER in immune regulation and its potential as a therapeutic target.


Assuntos
Proteína ADAM10 , Secretases da Proteína Precursora do Amiloide , Toxinas Bacterianas , Proteínas Hemolisinas , Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Receptores de Estrogênio , Receptores Acoplados a Proteínas G , Staphylococcus aureus , Proteína ADAM10/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Humanos , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/metabolismo , Proteínas Hemolisinas/metabolismo , Inflamassomos/metabolismo , Toxinas Bacterianas/metabolismo , Células THP-1 , Receptores de Estrogênio/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Proteínas de Membrana/agonistas , Caspase 1/metabolismo , Trifosfato de Adenosina/metabolismo , Macrófagos/imunologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/microbiologia , Dipeptídeos , Ácidos Hidroxâmicos
12.
Biosensors (Basel) ; 14(6)2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38920572

RESUMO

In this study, we report a multiplexed platform for the simultaneous determination of five marine toxins. The proposed biosensor is based on a disposable electrical printed (DEP) microarray composed of eight individually addressable carbon electrodes. The electrodeposition of gold nanoparticles on the carbon surface offers high conductivity and enlarges the electroactive area. The immobilization of thiolated aptamers on the AuNP-decorated carbon electrodes provides a stable, well-orientated and organized binary self-assembled monolayer for sensitive and accurate detection. A simple electrochemical multiplexed aptasensor based on AuNPs was designed to synchronously detect multiple cyanotoxins, namely, microcystin-LR (MC-LR), Cylindrospermopsin (CYL), anatoxin-α, saxitoxin and okadaic acid (OA). The choice of the five toxins was based on their widespread presence and toxicity to aquatic ecosystems and humans. Taking advantage of the conformational change of the aptamers upon target binding, cyanotoxin detection was achieved by monitoring the resulting electron transfer increase by square-wave voltammetry. Under the optimal conditions, the linear range of the proposed aptasensor was estimated to be from 0.018 nM to 200 nM for all the toxins, except for MC-LR where detection was possible within the range of 0.073 to 150 nM. Excellent sensitivity was achieved with the limits of detection of 0.0033, 0.0045, 0.0034, 0.0053 and 0.0048 nM for MC-LR, CYL, anatoxin-α, saxitoxin and OA, respectively. Selectivity studies were performed to show the absence of cross-reactivity between the five analytes. Finally, the application of the multiplexed aptasensor to tap water samples revealed very good agreement with the calibration curves obtained in buffer. This simple and accurate multiplexed platform could open the window for the simultaneous detection of multiple pollutants in different matrices.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Toxinas de Cianobactérias , Técnicas Eletroquímicas , Ouro , Toxinas Marinhas , Nanopartículas Metálicas , Microcistinas , Saxitoxina , Toxinas Marinhas/análise , Microcistinas/análise , Ouro/química , Saxitoxina/análise , Nanopartículas Metálicas/química , Toxinas Bacterianas/análise , Uracila/análise , Uracila/análogos & derivados , Tropanos/análise , Alcaloides/análise , Ácido Okadáico/análise , Eletrodos , Limite de Detecção
13.
Toxins (Basel) ; 16(6)2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38922128

RESUMO

The pathophysiology of Lyme disease, especially in its persistent form, remains to be determined. As many of the neurologic symptoms are similar to those seen in other toxin-associated disorders, a hypothesis was generated that B. burgdorferi, the causative agent of Lyme disease, may produce a neurotoxin to account for some of the symptoms. Using primers against known conserved bacterial toxin groups, and PCR technology, a candidate neurotoxin was discovered. The purified protein was temporarily named BbTox, and was subsequently found to be identical to BB0755, a protein deduced from the genome sequence of B. burgdorferi that has been annotated as a Z ribonuclease. BbTox has cytotoxic activity against cells of neural origin in tissue culture. Its toxic activity appears to be directed against cytoskeletal elements, similar to that seen with toxins of Clostridioides difficile and Clostridioides botulinum, but differing from that of cholera and E. coli toxins, and other toxins. It remains to be determined whether BbTox has direct cytotoxic effects on neural or glial cells in vivo, or its activity is primarily that of a ribonuclease analogous to other bacterial ribonucleases that are involved in antibiotic tolerance remains to be determined.


Assuntos
Borrelia burgdorferi , Doença de Lyme , Borrelia burgdorferi/genética , Borrelia burgdorferi/efeitos dos fármacos , Doença de Lyme/microbiologia , Doença de Lyme/tratamento farmacológico , Animais , Humanos , Toxinas Bacterianas/toxicidade , Citotoxinas/toxicidade , Sequência de Aminoácidos
14.
Toxins (Basel) ; 16(6)2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38922163

RESUMO

The rise in cyanobacterial blooms due to eutrophication and climate change has increased cyanotoxin presence in water. Most current water treatment plants do not effectively remove these toxins, posing a potential risk to public health. This study introduces a water treatment approach using nanostructured beads containing magnetic nanoparticles (MNPs) for easy removal from liquid suspension, coated with different adsorbent materials to eliminate cyanotoxins. Thirteen particle types were produced using activated carbon, CMK-3 mesoporous carbon, graphene, chitosan, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibers (TOCNF), esterified pectin, and calcined lignin as an adsorbent component. The particles' effectiveness for detoxification of microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-A (ATX-A) was assessed in an aqueous solution. Two particle compositions presented the best adsorption characteristics for the most common cyanotoxins. In the conditions tested, mesoporous carbon nanostructured particles, P1-CMK3, provide good removal of MC-LR and Merck-activated carbon nanostructured particles, P9-MAC, can remove ATX-A and CYN with high and fair efficacy, respectively. Additionally, in vitro toxicity of water treated with each particle type was evaluated in cultured cell lines, revealing no alteration of viability in human renal, neuronal, hepatic, and intestinal cells. Although further research is needed to fully characterise this new water treatment approach, it appears to be a safe, practical, and effective method for eliminating cyanotoxins from water.


Assuntos
Toxinas Bacterianas , Toxinas de Cianobactérias , Toxinas Marinhas , Microcistinas , Purificação da Água , Toxinas de Cianobactérias/química , Humanos , Microcistinas/toxicidade , Microcistinas/química , Microcistinas/isolamento & purificação , Toxinas Marinhas/toxicidade , Toxinas Marinhas/química , Toxinas Marinhas/isolamento & purificação , Purificação da Água/métodos , Adsorção , Toxinas Bacterianas/toxicidade , Toxinas Bacterianas/química , Toxinas Bacterianas/isolamento & purificação , Alcaloides/química , Alcaloides/toxicidade , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/toxicidade , Tropanos/química , Tropanos/toxicidade , Tropanos/isolamento & purificação , Nanoestruturas/química , Nanoestruturas/toxicidade , Uracila/análogos & derivados , Uracila/química , Uracila/toxicidade , Cianobactérias/química , Sobrevivência Celular/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/química
15.
Cell Host Microbe ; 32(6): 794-803, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38870897

RESUMO

Most bacteria live in communities, often with closely related strains and species with whom they must compete for space and resources. Consequently, bacteria have acquired or evolved mechanisms to antagonize competitors through the production of antibacterial toxins. Similar to bacterial systems that combat phage infection and mechanisms to thwart antibiotics, bacteria have also acquired and evolved features to protect themselves from antibacterial toxins. Just as there is a large body of research identifying and characterizing antibacterial proteins and toxin delivery systems, studies of bacterial mechanisms to resist and survive assault from competitors' weapons have also expanded tremendously. Emerging data are beginning to reveal protective processes and mechanisms that are as diverse as the toxins themselves. Protection against antibacterial toxins can be acquired by horizontal gene transfer, receptor or target alteration, induction of protective functions, physical barriers, and other diverse processes. Here, we review recent studies in this rapidly expanding field.


Assuntos
Bactérias , Toxinas Bacterianas , Bactérias/imunologia , Bactérias/genética , Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/imunologia , Transferência Genética Horizontal , Humanos , Viabilidade Microbiana , Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética
16.
Toxins (Basel) ; 16(6)2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38922136

RESUMO

Clostridioides difficile, a Gram-positive anaerobic bacterium, is the leading cause of hospital-acquired antibiotic-associated diarrhea worldwide. The severity of C. difficile infection (CDI) varies, ranging from mild diarrhea to life-threatening conditions such as pseudomembranous colitis and toxic megacolon. Central to the pathogenesis of the infection are toxins produced by C. difficile, with toxin A (TcdA) and toxin B (TcdB) as the main virulence factors. Additionally, some strains produce a third toxin known as C. difficile transferase (CDT). Toxins damage the colonic epithelium, initiating a cascade of cellular events that lead to inflammation, fluid secretion, and further tissue damage within the colon. Mechanistically, the toxins bind to cell surface receptors, internalize, and then inactivate GTPase proteins, disrupting the organization of the cytoskeleton and affecting various Rho-dependent cellular processes. This results in a loss of epithelial barrier functions and the induction of cell death. The third toxin, CDT, however, functions as a binary actin-ADP-ribosylating toxin, causing actin depolymerization and inducing the formation of microtubule-based protrusions. In this review, we summarize our current understanding of the interaction between C. difficile toxins and host cells, elucidating the functional consequences of their actions. Furthermore, we will outline how this knowledge forms the basis for developing innovative, toxin-based strategies for treating and preventing CDI.


Assuntos
Toxinas Bacterianas , Clostridioides difficile , Interações entre Hospedeiro e Microrganismos , Clostridioides difficile/genética , Clostridioides difficile/patogenicidade , Toxinas Bacterianas/química , Toxinas Bacterianas/genética , Toxinas Bacterianas/imunologia , Infecções por Clostridium/tratamento farmacológico , Infecções por Clostridium/microbiologia , Infecções por Clostridium/patologia , Ordem dos Genes , Inflamação/patologia , Humanos , Animais
17.
Int J Mol Sci ; 25(12)2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38928005

RESUMO

The pregnane X receptor (PXR) is a nuclear hormone receptor that plays a pivotal role in regulating gene expression in response to various ligands, particularly xenobiotics. In this context, the aim of this study was to shed light on the ligand affinity and functions of four NR1J1 paralogs identified in the marine mussel Mytilus galloprovincialis, employing a dual-luciferase reporter assay. To achieve this, the activation patterns of these paralogs in response to various toxins, including freshwater cyanotoxins (Anatoxin-a, Cylindrospermopsin, and Microcystin-LR, -RR, and -YR) and marine algal toxins (Nodularin, Saxitoxin, and Tetrodotoxin), alongside natural compounds (Saint John's Wort, Ursolic Acid, and 8-Methoxypsoralene) and microalgal extracts (Tetraselmis, Isochrysis, LEGE 95046, and LEGE 91351 extracts), were studied. The investigation revealed nuanced differences in paralog response patterns, highlighting the remarkable sensitivity of MgaNR1J1γ and MgaNR1J1δ paralogs to several toxins. In conclusion, this study sheds light on the intricate mechanisms of xenobiotic metabolism and detoxification, particularly focusing on the role of marine mussel NR1J1 in responding to a diverse array of compounds. Furthermore, comparative analysis with human PXR revealed potential species-specific adaptations in detoxification mechanisms, suggesting evolutionary implications. These findings deepen our understanding of PXR-mediated metabolism mechanisms, offering insights into environmental monitoring and evolutionary biology research.


Assuntos
Toxinas Marinhas , Mytilus , Receptor de Pregnano X , Animais , Receptor de Pregnano X/metabolismo , Receptor de Pregnano X/genética , Mytilus/metabolismo , Mytilus/genética , Humanos , Microcistinas/metabolismo , Microalgas/metabolismo , Microalgas/genética , Xenobióticos/metabolismo , Toxinas Bacterianas/metabolismo , Toxinas de Cianobactérias
18.
Int J Mol Sci ; 25(12)2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38928408

RESUMO

Trueperella pyogenes is an important opportunistic pathogenic bacterium widely distributed in the environment. Pyolysin (PLO) is a primary virulence factor of T. pyogenes and capable of lysing many different cells. PLO is a member of the cholesterol-dependent cytolysin (CDC) family of which the primary structure only presents a low level of homology with other members from 31% to 45%. By deeply studying PLO, we can understand the overall pathogenic mechanism of CDC family proteins. This study established a mouse muscle tissue model infected with recombinant PLO (rPLO) and its single-point mutations, rPLO N139K and rPLO F240A, and explored its mechanism of causing inflammatory damage. The inflammatory injury abilities of rPLO N139K and rPLO F240A are significantly reduced compared to rPLO. This study elaborated on the inflammatory mechanism of PLO by examining its unit point mutations in detail. Our data also provide a theoretical basis and practical significance for future research on toxins and bacteria.


Assuntos
Proteínas de Bactérias , Proteínas Hemolisinas , Proteína 3 que Contém Domínio de Pirina da Família NLR , Mutação Puntual , Animais , Camundongos , Proteínas Hemolisinas/metabolismo , Proteínas Hemolisinas/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Inflamação/metabolismo , Inflamação/genética , Potássio/metabolismo , Transdução de Sinais , Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/genética , Inflamassomos/metabolismo , Humanos
19.
Microbiol Spectr ; 12(7): e0394723, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38864670

RESUMO

Clostridioides difficile (C. difficile) is widely distributed in the intestinal tract of humans, animals, and in the environment. It is the most common cause of diarrhea associated with the use of antimicrobials in humans and among the most common healthcare-associated infections worldwide. Its pathogenesis is mainly due to the production of toxin A (TcdA), toxin B (TcdB), and a binary toxin (CDT), whose genetic variants may be associated with disease severity. We studied genetic diversity in 39 C. difficile isolates from adults and children attended at two Mexican hospitals, using different gene and genome typing methods and investigated their association with in vitro expression of toxins. Whole-genome sequencing in 39 toxigenic C. difficile isolates were used for multilocus sequence typing, tcdA, and tcdB typing sequence type, and phylogenetic analysis. Strains were grown in broth media, and expression of toxin genes was measured by real-time PCR and cytotoxicity in cell-culture assays. Clustering of strains by genome-wide phylogeny matched clade classification, forming different subclusters within each clade. The toxin profile tcdA+/tcdB+/cdt+ and clade 2/ST1 were the most prevalent among isolates from children and adults. Isolates presented two TcdA and three TcdB subtypes, of which TcdA2 and TcdB2 were more prevalent. Prevalent clades and toxin subtypes in strains from children differed from those in adult strains. Toxin gene expression or cytotoxicity was not associated with genotyping or toxin subtypes. In conclusion, genomic and phenotypic analysis shows high diversity among C. difficile isolates from patients with healthcare-associated diarrhea. IMPORTANCE: Clostridioides difficile is a toxin-producing bacterial pathogen recognized as the most common cause of diarrhea acquired primarily in healthcare settings. This bacterial species is diverse; its global population has been divided into five different clades using multilocus sequence typing, and strains may express different toxin subtypes that may be related to the clades and, importantly, to the severity and progression of disease. Genotyping of children strains differed from adults suggesting toxins might present a reduced toxicity. We studied extensively cytotoxicity, expression of toxins, whole genome phylogeny, and toxin typing in clinical C. difficile isolates. Most isolates presented a tcdA+/ tcdB+/cdt+ pattern, with high diversity in cytotoxicity and clade 2/ST1 was the most prevalent. However, they all had the same TcdA2/TcdB2 toxin subtype. Advances in genomics and bioinformatics tools offer the opportunity to understand the virulence of C. difficile better and find markers for better clinical use.


Assuntos
Toxinas Bacterianas , Clostridioides difficile , Infecções por Clostridium , Infecção Hospitalar , Diarreia , Variação Genética , Tipagem de Sequências Multilocus , Filogenia , Humanos , Clostridioides difficile/genética , Clostridioides difficile/classificação , Clostridioides difficile/isolamento & purificação , Diarreia/microbiologia , Diarreia/epidemiologia , México/epidemiologia , Criança , Toxinas Bacterianas/genética , Adulto , Infecções por Clostridium/microbiologia , Infecções por Clostridium/epidemiologia , Infecção Hospitalar/microbiologia , Infecção Hospitalar/epidemiologia , Proteínas de Bactérias/genética , Enterotoxinas/genética , Masculino , Pré-Escolar , Feminino , Prevalência , Adolescente , Sequenciamento Completo do Genoma , Fenótipo , Genoma Bacteriano/genética , Lactente , Pessoa de Meia-Idade , Genômica
20.
Environ Microbiol Rep ; 16(3): e13297, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38885952

RESUMO

The Winam Gulf (Kenya) is frequently impaired by cyanobacterial harmful algal blooms (cHABs) due to inadequate wastewater treatment and excess agricultural nutrient input. While phytoplankton in Lake Victoria have been characterized using morphological criteria, our aim is to identify potential toxin-producing cyanobacteria using molecular approaches. The Gulf was sampled over two successive summer seasons, and 16S and 18S ribosomal RNA gene sequencing was performed. Additionally, key genes involved in production of cyanotoxins were examined by quantitative PCR. Bacterial communities were spatially variable, forming distinct clusters in line with regions of the Gulf. Taxa associated with diazotrophy were dominant near Homa Bay. On the eastern side, samples exhibited elevated cyrA abundances, indicating genetic capability of cylindrospermopsin synthesis. Indeed, near the Nyando River mouth in 2022, cyrA exceeded 10 million copies L-1 where there were more than 6000 Cylindrospermopsis spp. cells mL-1. In contrast, the southwestern region had elevated mcyE gene (microcystin synthesis) detections near Homa Bay where Microcystis and Dolichospermum spp. were observed. These findings show that within a relatively small embayment, composition and toxin synthesis potential of cHABs can vary dramatically. This underscores the need for multifaceted management approaches and frequent cyanotoxin monitoring to reduce human health impacts.


Assuntos
Toxinas Bacterianas , Cianobactérias , Proliferação Nociva de Algas , Lagos , Lagos/microbiologia , Lagos/química , Quênia , Cianobactérias/genética , Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Cianobactérias/metabolismo , Toxinas Bacterianas/genética , Microcistinas/genética , RNA Ribossômico 16S/genética , Microbiota , Fitoplâncton/genética , Toxinas de Cianobactérias , Alcaloides/análise , Alcaloides/metabolismo , RNA Ribossômico 18S/genética , Filogenia
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