1
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Ashtiwi NM, Kim SO, Chandler JD, Rada B. The therapeutic potential of thiocyanate and hypothiocyanous acid against pulmonary infections. Free Radic Biol Med 2024; 219:104-111. [PMID: 38608822 PMCID: PMC11088529 DOI: 10.1016/j.freeradbiomed.2024.04.217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 03/18/2024] [Accepted: 04/09/2024] [Indexed: 04/14/2024]
Abstract
Hypothiocyanous acid (HOSCN) is an endogenous oxidant produced by peroxidase oxidation of thiocyanate (SCN-), an ubiquitous sulfur-containing pseudohalide synthesized from cyanide. HOSCN serves as a potent microbicidal agent against pathogenic bacteria, viruses, and fungi, functioning through thiol-targeting mechanisms, independent of currently approved antimicrobials. Additionally, SCN- reacts with hypochlorous acid (HOCl), a highly reactive oxidant produced by myeloperoxidase (MPO) at sites of inflammation, also producing HOSCN. This imparts both antioxidant and antimicrobial potential to SCN-. In this review, we discuss roles of HOSCN/SCN- in immunity and potential therapeutic implications for combating infections.
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Affiliation(s)
- Nuha Milad Ashtiwi
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Susan O Kim
- Pediatrics, Division of Pulmonary, Allergy & Immunology, Cystic Fibrosis, and Sleep Medicine, Emory University, Atlanta, GA, USA
| | - Joshua D Chandler
- Pediatrics, Division of Pulmonary, Allergy & Immunology, Cystic Fibrosis, and Sleep Medicine, Emory University, Atlanta, GA, USA; Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Balázs Rada
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
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2
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Bradley R, Simon D, Spiga L, Xiang Y, Takats Z, Williams H. Laser desorption rapid evaporative ionization mass spectrometry (LD-REIMS) demonstrates a direct impact of hypochlorous acid stress on PQS-mediated quorum sensing in Pseudomonas aeruginosa. mSystems 2024; 9:e0116523. [PMID: 38530056 PMCID: PMC11019781 DOI: 10.1128/msystems.01165-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/26/2024] [Indexed: 03/27/2024] Open
Abstract
To establish infections in human hosts, Pseudomonas aeruginosa must overcome innate immune-generated oxidative stress, such as the hypochlorous acid (HOCl) produced by neutrophils. We set out to find specific biomarkers of oxidative stress through the development of a protocol for the metabolic profiling of P. aeruginosa cultures grown in the presence of different oxidants using a novel ionization technique for mass spectrometry, laser desorption rapid evaporative ionization mass spectrometry (LD-REIMS). We demonstrated the ability of LD-REIMS to classify samples as untreated or treated with a specific oxidant with 100% accuracy and identified a panel of 54 metabolites with significantly altered concentrations after exposure to one or more of the oxidants. Key metabolic changes were conserved in P. aeruginosa clinical strains isolated from patients with cystic fibrosis lung infections. These data demonstrated that HOCl stress impacted the Pseudomonas quinolone signal (PQS) quorum sensing system. Ten 2-alkyl-4-quinolones (AHQs) associated with the PQS system were significantly lower in concentration in HOCl-stressed P. aeruginosa cultures, including 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), the most active signal molecule of the PQS system. The PQS system regulates the production of virulence factors, including pyocyanin and elastase, and their levels were markedly affected by HOCl stress. No pyocyanin was detectable and elastase concentrations were reduced by more than 75% in cultures grown with sub-lethal concentrations of HOCl, suggesting that this neutrophil-derived oxidant may disrupt the ability of P. aeruginosa to establish infections through interference with production of PQS-associated virulence factors. IMPORTANCE This work demonstrates that a high-throughput ambient ionization mass spectrometry method can be used successfully to study a bacterial stress response. Its application to the opportunistic pathogen Pseudomonas aeruginosa led to the identification of specific oxidative stress biomarkers, and demonstrated that hypochlorous acid, an oxidant specifically produced by human neutrophils during infection, affects quorum sensing and reduces production of the virulence factors pyocyanin and elastase. No pyocyanin was detectable and elastase levels were reduced by more than 75% in bacteria grown in the presence of hypochlorous acid. This approach has the potential to be widely applicable to the characterization of the stress responses of bacteria.
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Affiliation(s)
- Rob Bradley
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
| | - Daniel Simon
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
- The Rosalind Franklin Institute, Didcot, United Kingdom
| | - Livia Spiga
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
| | - Yuchen Xiang
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Zoltan Takats
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Huw Williams
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
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3
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Gray MJ. The role of metals in hypothiocyanite resistance in Escherichia coli. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.07.583962. [PMID: 38496647 PMCID: PMC10942458 DOI: 10.1101/2024.03.07.583962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The innate immune system employs a variety of antimicrobial oxidants to control and kill host-associated bacteria. Hypothiocyanite/hypothiocyanous acid (-OSCN/HOSCN) is one such antimicrobial oxidant that is synthesized by lactoperoxidase, myeloperoxidase, and eosinophil peroxidase at sites throughout the human body. HOSCN has potent antibacterial activity while being largely non-toxic towards human cells. The molecular mechanisms by which bacteria sense and defend themselves against HOSCN have only recently begun to be elaborated, notably by the discovery of bacterial HOSCN reductase (RclA), an HOSCN-degrading enzyme widely conserved among bacteria that live on epithelial surfaces. In this paper, I show that Ni2+ sensitizes Escherichia coli to HOSCN by inhibiting glutathione reductase, and that inorganic polyphosphate protects E. coli against this effect, probably by chelating Ni2+ ions. I also found that RclA is very sensitive to inhibition by Cu2+ and Zn2+, metals that are accumulated to high levels by innate immune cells, and that, surprisingly, thioredoxin and thioredoxin reductase are not involved in HOSCN stress resistance in E. coli. These results advance our understanding of the contribution of different oxidative stress response and redox buffering pathways to HOSCN resistance in E. coli and illustrate important interactions between metal ions and the enzymes bacteria use to defend themselves against oxidative stress.
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Affiliation(s)
- Michael J. Gray
- Department of Microbiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
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4
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Kristensen R, Andersen JB, Rybtke M, Jansen CU, Fritz BG, Kiilerich RO, Uhd J, Bjarnsholt T, Qvortrup K, Tolker-Nielsen T, Givskov M, Jakobsen TH. Inhibition of Pseudomonas aeruginosa quorum sensing by chemical induction of the MexEF-oprN efflux pump. Antimicrob Agents Chemother 2024; 68:e0138723. [PMID: 38189278 PMCID: PMC10848761 DOI: 10.1128/aac.01387-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 11/17/2023] [Indexed: 01/09/2024] Open
Abstract
The cell-to-cell communication system quorum sensing (QS), used by various pathogenic bacteria to synchronize gene expression and increase host invasion potentials, is studied as a potential target for persistent infection control. To search for novel molecules targeting the QS system in the Gram-negative opportunistic pathogen Pseudomonas aeruginosa, a chemical library consisting of 3,280 small compounds from LifeArc was screened. A series of 10 conjugated phenones that have not previously been reported to target bacteria were identified as inhibitors of QS in P. aeruginosa. Two lead compounds (ethylthio enynone and propylthio enynone) were re-synthesized for verification of activity and further elucidation of the mode of action. The isomeric pure Z-ethylthio enynone was used for RNA sequencing, revealing a strong inhibitor of QS-regulated genes, and the QS-regulated virulence factors rhamnolipid and pyocyanin were significantly decreased by treatment with the compounds. A transposon mutagenesis screen performed in a newly constructed lasB-gfp monitor strain identified the target of Z-ethylthio enynone in P. aeruginosa to be the MexEF-OprN efflux pump, which was further established using defined mex knockout mutants. Our data indicate that the QS inhibitory capabilities of Z-ethylthio enynone were caused by the drainage of intracellular signal molecules as a response to chemical-induced stimulation of the MexEF-oprN efflux pump, thereby inhibiting the autogenerated positive feedback and its enhanced signal-molecule synthesis.
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Affiliation(s)
- Rasmus Kristensen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bo Andersen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Morten Rybtke
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | | | - Blaine Gabriel Fritz
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Overgaard Kiilerich
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Uhd
- Department of Chemistry, Technical University of Denmark, Lyngby, Denmark
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Katrine Qvortrup
- Department of Chemistry, Technical University of Denmark, Lyngby, Denmark
| | - Tim Tolker-Nielsen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Michael Givskov
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Tim Holm Jakobsen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
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5
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Loi VV, Busche T, Schnaufer F, Kalinowski J, Antelmann H. The neutrophil oxidant hypothiocyanous acid causes a thiol-specific stress response and an oxidative shift of the bacillithiol redox potential in Staphylococcus aureus. Microbiol Spectr 2023; 11:e0325223. [PMID: 37930020 PMCID: PMC10715087 DOI: 10.1128/spectrum.03252-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023] Open
Abstract
IMPORTANCE Staphylococcus aureus colonizes the skin and the airways but can also lead to life-threatening systemic and chronic infections. During colonization and phagocytosis by immune cells, S. aureus encounters the thiol-reactive oxidant HOSCN. The understanding of the adaptation mechanisms of S. aureus toward HOSCN stress is important to identify novel drug targets to combat multi-resistant S. aureus isolates. As a defense mechanism, S. aureus uses the flavin disulfide reductase MerA, which functions as HOSCN reductase and protects against HOSCN stress. Moreover, MerA homologs have conserved functions in HOSCN detoxification in other bacteria, including intestinal and respiratory pathogens. In this work, we studied the comprehensive thiol-reactive mode of action of HOSCN and its effect on the reversible shift of the E BSH to discover new defense mechanisms against the neutrophil oxidant. These findings provide new leads for future drug design to fight the pathogen at the sites of colonization and infections.
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Affiliation(s)
- Vu Van Loi
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
| | - Tobias Busche
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Franziska Schnaufer
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
| | - Jörn Kalinowski
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Haike Antelmann
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
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6
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Thiroux A, Labanowski J, Venisse N, Crapart S, Boisgrollier C, Linares C, Berjeaud J, Villéger R, Crépin A. Exposure to endocrine disruptors promotes biofilm formation and contributes to increased virulence of Pseudomonas aeruginosa. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023; 15:740-756. [PMID: 37586891 PMCID: PMC10667657 DOI: 10.1111/1758-2229.13190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 07/07/2023] [Indexed: 08/18/2023]
Abstract
Anthropogenic activities contribute to the spread of chemicals considered as endocrine disruptors (ED) in freshwater ecosystems. While several studies have reported interactions of EDs with organisms in those ecosystems, very few have assessed the effect of these compounds on pathogenic bacteria. Here we have evaluated the impact of five EDs found in aquatic resources on the virulence of human pathogen P. aeruginosa. ED concentrations in French aquatic resources of bisphenol A (BPA), dibutyl phthalate (DBP), ethylparaben (EP), methylparaben (MP) and triclosan (TCS) at mean molar concentration were 1.13, 3.58, 0.53, 0.69, and 0.81 nM respectively. No impact on bacterial growth was observed at EDs highest tested concentration. Swimming motility of P. aeruginosa decreased to 28.4% when exposed to EP at 100 μM. Swarming motility increased, with MP at 1 nM, 10 and 100 μM (1.5-fold); conversely, a decrease of 78.5%, with DBP at 100 μM was observed. Furthermore, exposure to 1 nM BPA, DBP and EP increased biofilm formation. P. aeruginosa adhesion to lung cells was two-fold higher upon exposure to 1 nM EP. We demonstrate that ED exposure may simultaneously decrease mobility and increase cell adhesion and biofilm formation, which may promote colonisation and establishment of the pathogen.
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Affiliation(s)
- Audrey Thiroux
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
| | - Jérôme Labanowski
- Université de PoitiersUMR 7285, Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP)PoitiersFrance
| | - Nicolas Venisse
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
- Université de Poitiers, CHU de Poitiers, INSERMCentre d'investigation clinique CIC1402PoitiersFrance
| | - Stéphanie Crapart
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
| | - Chloé Boisgrollier
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
| | - Carlos Linares
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
| | - Jean‐Marc Berjeaud
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
| | - Romain Villéger
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
| | - Alexandre Crépin
- Université de Poitiers, UMR CNRS 7267Ecologie et Biologie des InteractionsPoitiersFrance
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7
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da Cruz Nizer WS, Adams ME, Inkovskiy V, Beaulieu C, Overhage J. The secondary metabolite hydrogen cyanide protects Pseudomonas aeruginosa against sodium hypochlorite-induced oxidative stress. Front Microbiol 2023; 14:1294518. [PMID: 38033579 PMCID: PMC10687435 DOI: 10.3389/fmicb.2023.1294518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/01/2023] [Indexed: 12/02/2023] Open
Abstract
The high pathogenicity of Pseudomonas aeruginosa is attributed to the production of many virulence factors and its resistance to several antimicrobials. Among them, sodium hypochlorite (NaOCl) is a widely used disinfectant due to its strong antimicrobial effect. However, bacteria develop many mechanisms to survive the damage caused by this agent. Therefore, this study aimed to identify novel mechanisms employed by P. aeruginosa to resist oxidative stress induced by the strong oxidizing agent NaOCl. We analyzed the growth of the P. aeruginosa mutants ΔkatA, ΔkatE, ΔahpC, ΔahpF, ΔmsrA at 1 μg/mL NaOCl, and showed that these known H2O2 resistance mechanisms are also important for the survival of P. aeruginosa under NaOCl stress. We then conducted a screening of the P. aeruginosa PA14 transposon insertion mutant library and identified 48 mutants with increased susceptibility toward NaOCl. Among them were 10 mutants with a disrupted nrdJa, bvlR, hcnA, orn, sucC, cysZ, nuoJ, PA4166, opmQ, or thiC gene, which also exhibited a significant growth defect in the presence of NaOCl. We focussed our follow-up experiments (i.e., growth analyzes and kill-kinetics) on mutants with defect in the synthesis of the secondary metabolite hydrogen cyanide (HCN). We showed that HCN produced by P. aeruginosa contributes to its resistance toward NaOCl as it acts as a scavenger molecule, quenching the toxic effects of NaOCl.
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Affiliation(s)
| | | | | | | | - Joerg Overhage
- Department of Health Sciences, Carleton University, Ottawa, ON, Canada
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8
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Nontaleerak B, Eurtivong C, Weeraphan C, Buncherd H, Chokchaichamnankit D, Srisomsap C, Svasti J, Sukchawalit R, Mongkolsuk S. The redox-sensing mechanism of Agrobacterium tumefaciens NieR as a thiol-based oxidation sensor for hypochlorite stress. Free Radic Biol Med 2023; 208:211-220. [PMID: 37544488 DOI: 10.1016/j.freeradbiomed.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/20/2023] [Accepted: 08/01/2023] [Indexed: 08/08/2023]
Abstract
NieR is a TetR family transcriptional repressor previously shown to regulate the NaOCl-inducible efflux pump NieAB in Agrobacterium tumefaciens. NieR is an ortholog of Escherichia coli NemR that specifically senses hypochlorite through the redox switch of a reversible sulfenamide bond between C106 and K175. The amino acid sequence of NieR contains only one cysteine. NieR has C104 and R166, which correspond to C106 and K175 of NemR, respectively. The aim of this study was to investigate the redox-sensing mechanism of NieR under NaOCl stress. C104 and R166 were subjected to mutagenesis to determine their roles. Although the substitution of R166 by alanine slightly reduced its DNA-binding activity, NieR retained its repressor function. By contrast, the DNA-binding and repression activities of NieR were completely lost when C104 was replaced by alanine. C104 substitution with serine only partially impaired the repressor function. Mass spectrometry analysis revealed an intermolecular disulfide bond between the C104 residues of NieR monomers. This study demonstrates the engagement of C104 in the mechanism of NaOCl sensing. C104 oxidation induced the formation of a disulfide-linked dimer that was likely to alter conformation, thus abolishing the DNA-binding ability of NieR and derepressing the target genes.
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Affiliation(s)
- Benya Nontaleerak
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok, 10210, Thailand
| | - Chatchakorn Eurtivong
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Mahidol University, 447 Si Ayutthaya Road, Ratchathewi, Bangkok 10400, Thailand
| | - Churat Weeraphan
- Laboratory of Biochemistry, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Hansuk Buncherd
- Laboratory of Biochemistry, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand; Faculty of Medical Technology, Prince of Songkla University, Songkhla 90112, Thailand; Medical Science Research and Innovation Institute, Prince of Songkla University, Songkhla 90112, Thailand
| | | | - Chantragan Srisomsap
- Laboratory of Biochemistry, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Jisnuson Svasti
- Laboratory of Biochemistry, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Rojana Sukchawalit
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok, 10210, Thailand; Program in Applied Biological Sciences, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok 10210, Thailand; Center of Excellence on Environmental Health and Toxicology (EHT), OPS, MHESI, Thailand.
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok, 10210, Thailand; Center of Excellence on Environmental Health and Toxicology (EHT), OPS, MHESI, Thailand
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9
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Shearer HL, Pace PE, Smith LM, Fineran PC, Matthews AJ, Camilli A, Dickerhof N, Hampton MB. Identification of Streptococcus pneumoniae genes associated with hypothiocyanous acid tolerance through genome-wide screening. J Bacteriol 2023; 205:e0020823. [PMID: 37791755 PMCID: PMC10601753 DOI: 10.1128/jb.00208-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/01/2023] [Indexed: 10/05/2023] Open
Abstract
Streptococcus pneumoniae is a commensal bacterium and invasive pathogen that causes millions of deaths worldwide. The pneumococcal vaccine offers limited protection, and the rise of antimicrobial resistance will make treatment increasingly challenging, emphasizing the need for new antipneumococcal strategies. One possibility is to target antioxidant defenses to render S. pneumoniae more susceptible to oxidants produced by the immune system. Human peroxidase enzymes will convert bacterial-derived hydrogen peroxide to hypothiocyanous acid (HOSCN) at sites of colonization and infection. Here, we used saturation transposon mutagenesis and deep sequencing to identify genes that enable S. pneumoniae to tolerate HOSCN. We identified 37 genes associated with S. pneumoniae HOSCN tolerance, including genes involved in metabolism, membrane transport, DNA repair, and oxidant detoxification. Single-gene deletion mutants of the identified antioxidant defense genes sodA, spxB, trxA, and ahpD were generated and their ability to survive HOSCN was assessed. With the exception of ΔahpD, all deletion mutants showed significantly greater sensitivity to HOSCN, validating the result of the genome-wide screen. The activity of hypothiocyanous acid reductase or glutathione reductase, known to be important for S. pneumoniae tolerance of HOSCN, was increased in three of the mutants, highlighting the compensatory potential of antioxidant systems. Double deletion of the gene encoding glutathione reductase and sodA sensitized the bacteria significantly more than single deletion. The HOSCN defense systems identified in this study may be viable targets for novel therapeutics against this deadly pathogen. IMPORTANCE Streptococcus pneumoniae is a human pathogen that causes pneumonia, bacteremia, and meningitis. Vaccination provides protection only against a quarter of the known S. pneumoniae serotypes, and the bacterium is rapidly becoming resistant to antibiotics. As such, new treatments are required. One strategy is to sensitize the bacteria to killing by the immune system. In this study, we performed a genome-wide screen to identify genes that help this bacterium resist oxidative stress exerted by the host at sites of colonization and infection. By identifying a number of critical pneumococcal defense mechanisms, our work provides novel targets for antimicrobial therapy.
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Affiliation(s)
- Heather L. Shearer
- Department of Pathology and Biomedical Science, Mātai Hāora - Centre for Redox Biology and Medicine, University of Otago Christchurch, Christchurch, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Otago, New Zealand
| | - Paul E. Pace
- Department of Pathology and Biomedical Science, Mātai Hāora - Centre for Redox Biology and Medicine, University of Otago Christchurch, Christchurch, New Zealand
| | - Leah M. Smith
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
| | - Peter C. Fineran
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Otago, New Zealand
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
| | - Allison J. Matthews
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Andrew Camilli
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Nina Dickerhof
- Department of Pathology and Biomedical Science, Mātai Hāora - Centre for Redox Biology and Medicine, University of Otago Christchurch, Christchurch, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Otago, New Zealand
| | - Mark B. Hampton
- Department of Pathology and Biomedical Science, Mātai Hāora - Centre for Redox Biology and Medicine, University of Otago Christchurch, Christchurch, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Otago, New Zealand
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10
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Meredith JD, Gray MJ. Hypothiocyanite and host-microbe interactions. Mol Microbiol 2023; 119:302-311. [PMID: 36718113 DOI: 10.1111/mmi.15025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 02/01/2023]
Abstract
The pseudohypohalous acid hypothiocyanite/hypothiocyanous acid (OSCN- /HOSCN) has been known to play an antimicrobial role in mammalian immunity for decades. It is a potent oxidant that kills bacteria but is non-toxic to human cells. Produced from thiocyanate (SCN- ) and hydrogen peroxide (H2 O2 ) in a variety of body sites by peroxidase enzymes, HOSCN has been explored as an agent of food preservation, pathogen killing, and even improved toothpaste. However, despite the well-recognized antibacterial role HOSCN plays in host-pathogen interactions, little is known about how bacteria sense and respond to this oxidant. In this work, we will summarize what is known and unknown about HOSCN in innate immunity and recent advances in understanding the responses that both pathogenic and non-pathogenic bacteria mount against this antimicrobial agent, highlighting studies done with three model organisms, Escherichia coli, Streptococcus spp., and Pseudomonas aeruginosa.
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Affiliation(s)
- Julia D Meredith
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, USA
| | - Michael J Gray
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, USA
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11
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Cangui-Panchi SP, Ñacato-Toapanta AL, Enríquez-Martínez LJ, Salinas-Delgado GA, Reyes J, Garzon-Chavez D, Machado A. Battle royale: Immune response on biofilms – host-pathogen interactions. CURRENT RESEARCH IN IMMUNOLOGY 2023; 4:100057. [PMID: 37025390 PMCID: PMC10070391 DOI: 10.1016/j.crimmu.2023.100057] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/08/2023] [Accepted: 03/20/2023] [Indexed: 03/29/2023] Open
Abstract
The research interest of the scientific community in biofilm-forming microorganisms is growing due to the problems caused by their infections affecting humans and animals, mainly because of the difficulty of the host immune system in eradicating these microbial complex communities and the increasing antimicrobial resistance rates worldwide. This review describes the virulence factors and their interaction with the microbial communities of four well-known and highly biofilm-forming pathogens, more exactly, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus spp., and Candida spp. The innate and adaptive immune responses caused by the infection with these microorganisms and their evasion to the host immune system by biofilm formation are discussed in the present work. The relevance of the differences in the expression of certain virulence factors and the immune response in biofilm-associated infections when compared to planktonic infections is usually described as the biofilm architecture protects the pathogen and alters the host immune responses, here we extensively discussed these mechanisms.
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Affiliation(s)
- Sandra Pamela Cangui-Panchi
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Microbiología, Laboratorio de Bacteriología, Quito, Ecuador
| | - Anahí Lizbeth Ñacato-Toapanta
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Microbiología, Laboratorio de Bacteriología, Quito, Ecuador
| | - Leonardo Joshué Enríquez-Martínez
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Microbiología, Laboratorio de Bacteriología, Quito, Ecuador
| | - Gabriela Alexandra Salinas-Delgado
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Microbiología, Laboratorio de Bacteriología, Quito, Ecuador
| | - Jorge Reyes
- Hospital del Instituto Ecuatoriano de Seguridad Social (IESS) Quito-Sur, Quito, Ecuador
- Facultad de Ciencias Químicas, Universidad Central del Ecuador, Quito, Ecuador
| | - Daniel Garzon-Chavez
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias de la Salud, Quito, Ecuador
| | - António Machado
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Microbiología, Laboratorio de Bacteriología, Quito, Ecuador
- Corresponding author.
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Grace A, Sahu R, Owen DR, Dennis VA. Pseudomonas aeruginosa reference strains PAO1 and PA14: A genomic, phenotypic, and therapeutic review. Front Microbiol 2022; 13:1023523. [PMID: 36312971 PMCID: PMC9607943 DOI: 10.3389/fmicb.2022.1023523] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 09/28/2022] [Indexed: 11/25/2022] Open
Abstract
Pseudomonas aeruginosa is a ubiquitous, motile, gram-negative bacterium that has been recently identified as a multi-drug resistant pathogen in critical need of novel therapeutics. Of the approximately 5,000 strains, PAO1 and PA14 are common laboratory reference strains, modeling moderately and hyper-virulent phenotypes, respectively. PAO1 and PA14 have been instrumental in facilitating the discovery of novel drug targets, testing novel therapeutics, and supplying critical genomic information on the bacterium. While the two strains have contributed to a wide breadth of knowledge on the natural behaviors and therapeutic susceptibilities of P. aeruginosa, they have demonstrated significant deviations from observations in human infections. Many of these deviations are related to experimental inconsistencies in laboratory strain environment that complicate and, at times, terminate translation from laboratory results to clinical applications. This review aims to provide a comparative analysis of the two strains and potential methods to improve their clinical relevance.
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Affiliation(s)
- Amber Grace
- Department of Biological Sciences, Alabama State University, Montgomery, AL, United States
| | - Rajnish Sahu
- Department of Biological Sciences, Alabama State University, Montgomery, AL, United States
| | | | - Vida A. Dennis
- Department of Biological Sciences, Alabama State University, Montgomery, AL, United States
- *Correspondence: Vida A. Dennis,
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Redox-Mediated Inactivation of the Transcriptional Repressor RcrR is Responsible for Uropathogenic Escherichia coli's Increased Resistance to Reactive Chlorine Species. mBio 2022; 13:e0192622. [PMID: 36073817 PMCID: PMC9600549 DOI: 10.1128/mbio.01926-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The ability to overcome stressful environments is critical for pathogen survival in the host. One challenge for bacteria is the exposure to reactive chlorine species (RCS), which are generated by innate immune cells as a critical part of the oxidative burst. Hypochlorous acid (HOCl) is the most potent antimicrobial RCS and is associated with extensive macromolecular damage in the phagocytized pathogen. However, bacteria have evolved defense strategies to alleviate the effects of HOCl-mediated damage. Among these are RCS-sensing transcriptional regulators that control the expression of HOCl-protective genes under non-stress and HOCl stress. Uropathogenic Escherichia coli (UPEC), the major causative agent of urinary tract infections (UTIs), is particularly exposed to infiltrating neutrophils during pathogenesis; however, their responses to and defenses from HOCl are still completely unexplored. Here, we present evidence that UPEC strains tolerate higher levels of HOCl and are better protected from neutrophil-mediated killing compared with other E. coli. Transcriptomic analysis of HOCl-stressed UPEC revealed the upregulation of an operon consisting of three genes, one of which encodes the transcriptional regulator RcrR. We identified RcrR as a HOCl-responsive transcriptional repressor, which, under non-stress conditions, is bound to the operator and represses the expression of its target genes. During HOCl exposure, however, the repressor forms reversible intermolecular disulfide bonds and dissociates from the DNA resulting in the derepression of the operon. Deletion of one of the target genes renders UPEC significantly more susceptible to HOCl and phagocytosis indicating that the HOCl-mediated induction of the regulon plays a major role for UPEC’s HOCl resistance.
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Abstract
Hypothiocyanite and hypothiocyanous acid (OSCN-/HOSCN) are pseudohypohalous acids released by the innate immune system which are capable of rapidly oxidizing sulfur-containing amino acids, causing significant protein aggregation and damage to invading bacteria. HOSCN is abundant in saliva and airway secretions and has long been considered a highly specific antimicrobial that is nearly harmless to mammalian cells. However, certain bacteria, commensal and pathogenic, are able to escape damage by HOSCN and other harmful antimicrobials during inflammation, which allows them to continue to grow and, in some cases, cause severe disease. The exact genes or mechanisms by which bacteria respond to HOSCN have not yet been elucidated. We have found, in Escherichia coli, that the flavoprotein RclA, previously implicated in reactive chlorine resistance, reduces HOSCN to thiocyanate with near-perfect catalytic efficiency and strongly protects E. coli against HOSCN toxicity. This is notable in E. coli because this species thrives in the chronically inflamed environment found in patients with inflammatory bowel disease and is able to compete with and outgrow other important commensal organisms, suggesting that HOSCN may be a relevant antimicrobial in the gut, which has not previously been explored. RclA is conserved in a variety of epithelium-colonizing bacteria, implicating its HOSCN reductase activity in a variety of host-microbe interactions. We show that an rclA mutant of the probiotic Limosilactobacillus reuteri is sensitive to HOSCN and that RclA homologs from Staphylococcus aureus, Streptococcus pneumoniae, and Bacteroides thetaiotaomicron all have potent protective activity against HOSCN when expressed in E. coli.
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15
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Oxidative Stress Response in Pseudomonas aeruginosa. Pathogens 2021; 10:pathogens10091187. [PMID: 34578219 PMCID: PMC8466533 DOI: 10.3390/pathogens10091187] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/06/2021] [Accepted: 09/08/2021] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative environmental and human opportunistic pathogen highly adapted to many different environmental conditions. It can cause a wide range of serious infections, including wounds, lungs, the urinary tract, and systemic infections. The high versatility and pathogenicity of this bacterium is attributed to its genomic complexity, the expression of several virulence factors, and its intrinsic resistance to various antimicrobials. However, to thrive and establish infection, P. aeruginosa must overcome several barriers. One of these barriers is the presence of oxidizing agents (e.g., hydrogen peroxide, superoxide, and hypochlorous acid) produced by the host immune system or that are commonly used as disinfectants in a variety of different environments including hospitals. These agents damage several cellular molecules and can cause cell death. Therefore, bacteria adapt to these harsh conditions by altering gene expression and eliciting several stress responses to survive under oxidative stress. Here, we used PubMed to evaluate the current knowledge on the oxidative stress responses adopted by P. aeruginosa. We will describe the genes that are often differently expressed under oxidative stress conditions, the pathways and proteins employed to sense and respond to oxidative stress, and how these changes in gene expression influence pathogenicity and the virulence of P. aeruginosa. Understanding these responses and changes in gene expression is critical to controlling bacterial pathogenicity and developing new therapeutic agents.
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16
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Cianciulli Sesso A, Lilić B, Amman F, Wolfinger MT, Sonnleitner E, Bläsi U. Gene Expression Profiling of Pseudomonas aeruginosa Upon Exposure to Colistin and Tobramycin. Front Microbiol 2021; 12:626715. [PMID: 33995291 PMCID: PMC8120321 DOI: 10.3389/fmicb.2021.626715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/31/2021] [Indexed: 11/22/2022] Open
Abstract
Pseudomonas aeruginosa (Pae) is notorious for its high-level resistance toward clinically used antibiotics. In fact, Pae has rendered most antimicrobials ineffective, leaving polymyxins and aminoglycosides as last resort antibiotics. Although several resistance mechanisms of Pae are known toward these drugs, a profounder knowledge of hitherto unidentified factors and pathways appears crucial to develop novel strategies to increase their efficacy. Here, we have performed for the first time transcriptome analyses and ribosome profiling in parallel with strain PA14 grown in synthetic cystic fibrosis medium upon exposure to polymyxin E (colistin) and tobramycin. This approach did not only confirm known mechanisms involved in colistin and tobramycin susceptibility but revealed also as yet unknown functions/pathways. Colistin treatment resulted primarily in an anti-oxidative stress response and in the de-regulation of the MexT and AlgU regulons, whereas exposure to tobramycin led predominantly to a rewiring of the expression of multiple amino acid catabolic genes, lower tricarboxylic acid (TCA) cycle genes, type II and VI secretion system genes and genes involved in bacterial motility and attachment, which could potentially lead to a decrease in drug uptake. Moreover, we report that the adverse effects of tobramycin on translation are countered with enhanced expression of genes involved in stalled ribosome rescue, tRNA methylation and type II toxin-antitoxin (TA) systems.
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Affiliation(s)
- Anastasia Cianciulli Sesso
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Branislav Lilić
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Fabian Amman
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Michael T Wolfinger
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria.,Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - Elisabeth Sonnleitner
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Udo Bläsi
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
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