Pseudomonas aeruginosa las and rhl quorum-sensing systems are important for infection and inflammation in a rat prostatitis model

Pseudomonas aeruginosa frequently acts as an opportunistic pathogen of mucosal surfaces; yet, despite causing aggressive prostatitis in some men, its role as a pathogen in the prostate has not been investigated. Consequently, we developed a Ps. aeruginosa infection model in the rat prostate by instilling wild-type (WT) Ps. aeruginosa strain PAO1 into the rat prostate. It was found that Ps. aeruginosa produced acute and chronic infections in this mucosal tissue as determined by bacterial colonization, gross morphology, tissue damage and inflammatory markers. WT strain PAO1 and its isogenic mutant PAO-JP2, in which both the lasI and rhlI quorum-sensing signal systems have been silenced, were compared during both acute and chronic prostate infections. In acute infections, bacterial numbers and inflammatory markers were comparable between WT PA01 and PAO-JP2; however, considerably less tissue damage occurred in infections with PAO-JP2. Chronic infections with PAO-JP2 resulted in reduced bacterial colonization, tissue damage and inflammation as compared to WT PAO1 infections. Therefore, the quorum-sensing lasI and rhlI genes in Ps. aeruginosa affect acute prostate infections, but play a considerably more important role in maintaining chronic infections. We have thus developed a highly reproducible model for the study of Ps. aeruginosa virulence in the prostate.

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PrtR Homeostasis Contributes to Pseudomonas aeruginosa Pathogenesis and Resistance against Ciprofloxacin

Infection and Immunity ◽

10.1128/iai.01388-13 ◽

2014 ◽

Vol 82 (4) ◽

pp. 1638-1647 ◽

Cited By ~ 28

Author(s):

Ziyu Sun ◽

Jing Shi ◽

Chang Liu ◽

Yongxin Jin ◽

Kewei Li ◽

...

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Bacterial Colonization ◽

Mrna Level ◽

Sos Response ◽

Opportunistic Pathogen ◽

Host Cells ◽

Chronic Infections ◽

Mobility Shift ◽

Content Type

ABSTRACTPseudomonas aeruginosais an opportunistic pathogen that causes acute and chronic infections in humans. Pyocins are bacteriocins produced byP. aeruginosathat are usually released through lysis of the producer strains. Expression of pyocin genes is negatively regulated by PrtR, which gets cleaved under SOS response, leading to upregulation of pyocin synthetic genes. Previously, we demonstrated that PrtR is required for the expression of type III secretion system (T3SS), which is an important virulence component ofP. aeruginosa. In this study, we demonstrate that mutation inprtRresults in reduced bacterial colonization in a mouse acute pneumonia model. Examination of bacterial and host cells in the bronchoalveolar lavage fluids from infected mice revealed that expression of PrtR is induced by reactive oxygen species (ROS) released by neutrophils. We further demonstrate that treatment with hydrogen peroxide or ciprofloxacin, known to induce the SOS response and pyocin production, resulted in an elevated PrtR mRNA level. Overexpression of PrtR by atacpromoter repressed the endogenousprtRpromoter activity, and electrophoretic mobility shift assay revealed that PrtR binds to its own promoter, suggesting an autorepressive mechanism of regulation. A high level of PrtR expressed from a plasmid resulted in increased T3SS gene expression during infection and higher resistance against ciprofloxacin. Overall, our results suggest that the autorepression of PrtR contributes to the maintenance of a relatively stable level of PrtR, which is permissive to T3SS gene expression in the presence of ROS while increasing bacterial tolerance to stresses, such as ciprofloxacin, by limiting pyocin production.

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Poly (acetyl arginyl) glucosamine attenuates Pseudomonas aeruginosa in a rat lung infection model

10.1101/2021.09.15.460521 ◽

2021 ◽

Author(s):

Bryan Garcia ◽

Melissa S. McDaniel ◽

Allister J. Loughran ◽

J. Dixon Johns ◽

Vidya Narayanaswamy ◽

...

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Respiratory Infections ◽

Bacterial Species ◽

Membrane Integrity ◽

Opportunistic Pathogen ◽

Infection Model ◽

Total Biomass ◽

Chronic Infections

Pseudomonas aeruginosa is a common opportunistic pathogen that can cause chronic infections in multiple disease states, including respiratory infections in patients with cystic fibrosis (CF) and non-CF bronchiectasis. Like many opportunists, P. aeruginosa forms multicellular biofilm communities that are widely thought to be an important determinant of bacterial persistence and resistance to antimicrobials and host immune effectors during chronic/recurrent infections. Poly (acetyl, arginyl) glucosamine (PAAG) is a glycopolymer which has antimicrobial activity against a broad range of bacterial species, and also has mucolytic activity which can normalize rheologic properties of cystic fibrosis mucus. In this study, we sought to evaluate the effect of PAAG on P. aeruginosa bacteria within biofilms in vitro, and in the context of experimental pulmonary infection in a rodent infection model. PAAG treatment caused significant bactericidal activity against P. aeruginosa biofilms, and a reduction in the total biomass of preformed P. aeruginosa biofilms on abiotic surfaces, as well as on the surface of immortalized cystic fibrosis human bronchial epithelial cells. Studies of membrane integrity indicated that PAAG causes changes to P. aeruginosa cell morphology and dysregulates membrane polarity. PAAG treatment reduced infection and consequent tissue inflammation in experimental P. aeruginosa rat infections. Based on these findings we conclude that PAAG represents a novel means to combat P. aeruginosa infection, which may warrant further evaluation as a therapeutic.

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Pseudomonas aeruginosa Forms Biofilms in Acute Infection Independent of Cell-to-Cell Signaling

Infection and Immunity ◽

10.1128/iai.00586-07 ◽

2007 ◽

Vol 75 (8) ◽

pp. 3715-3721 ◽

Cited By ~ 108

Author(s):

J. Andy Schaber ◽

W. Jeffrey Triffo ◽

Sang Jin Suh ◽

Jeffrey W. Oliver ◽

Mary Catherine Hastert ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Bacterial Colonization ◽

Acute Infection ◽

Opportunistic Pathogen ◽

Confocal Scanning Laser Microscopy ◽

Chronic Infections ◽

Signaling Mechanism ◽

Confocal Scanning Laser

ABSTRACT Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 h of infection in thermally injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections as well. Using light, electron, and confocal scanning laser microscopy, P. aeruginosa biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild-type and QS-deficient P. aeruginosa strains formed similar biofilms in vivo. Our findings demonstrate that P. aeruginosa forms biofilms on specific host tissues independently of QS.

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The flavanone naringenin reduces the production of quorum sensing-controlled virulence factors in Pseudomonas aeruginosa PAO1

Microbiology ◽

10.1099/mic.0.049338-0 ◽

2011 ◽

Vol 157 (7) ◽

pp. 2120-2132 ◽

Cited By ~ 123

Author(s):

Olivier M. Vandeputte ◽

Martin Kiendrebeogo ◽

Tsiry Rasamiravaka ◽

Caroline Stévigny ◽

Pierre Duez ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Pathogenic Bacteria ◽

Opportunistic Pathogen ◽

Homoserine Lactone ◽

Gene Products ◽

Strain Pao1 ◽

Preliminary Screening ◽

Mutant Strains

Preliminary screening of the Malagasy plant Combretum albiflorum for compounds attenuating the production of quorum sensing (QS)-controlled virulence factors in bacteria led to the identification of active fractions containing flavonoids. In the present study, several flavonoids belonging to the flavone, flavanone, flavonol and chalcone structural groups were screened for their capacity to reduce the production of QS-controlled factors in the opportunistic pathogen Pseudomonas aeruginosa (strain PAO1). Flavanones (i.e. naringenin, eriodictyol and taxifolin) significantly reduced the production of pyocyanin and elastase in P. aeruginosa without affecting bacterial growth. Consistently, naringenin and taxifolin reduced the expression of several QS-controlled genes (i.e. lasI, lasR, rhlI, rhlR, lasA, lasB, phzA1 and rhlA) in P. aeruginosa PAO1. Naringenin also dramatically reduced the production of the acylhomoserine lactones N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) and N-butanoyl-l-homoserine lactone (C4-HSL), which is driven by the lasI and rhlI gene products, respectively. In addition, using mutant strains deficient for autoinduction (ΔlasI and ΔrhlI) and LasR- and RhlR-based biosensors, it was shown that QS inhibition by naringenin not only is the consequence of a reduced production of autoinduction compounds but also results from a defect in the proper functioning of the RlhR–C4-HSL complex. Widely distributed in the plant kingdom, flavonoids are known for their numerous and determinant roles in plant physiology, plant development and in the success of plant–rhizobia interactions, but, as shown here, some of them also have a role as inhibitors of the virulence of pathogenic bacteria by interfering with QS mechanisms.

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Uncovering the dynamic mechanisms of the Pseudomonas aeruginosa quorum sensing and virulence networks using Boolean modelling

10.1101/756551 ◽

2019 ◽

Author(s):

Manuel Banzhaf ◽

Osbaldo Resendis-Antonio ◽

M. Lisandra Zepeda-Mendoza

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Regulatory Networks ◽

Opportunistic Pathogen ◽

Resistance Mechanisms ◽

System Level ◽

Clear Understanding ◽

Chronic Infections ◽

Modelling Framework

AbstractIntroductionPseudomonas aeruginosa is an opportunistic pathogen with an extraordinary metabolic adaptability and a large repertoire of virulence factors that allow it to cause acute and chronic infections. Treatment of P. aeruginosa infections often fail due to its antibiotic resistance mechanisms, thus novel strategies aim at targeting virulence factors instead of growth-related features. However, there is currently not a clear understanding of the dynamic nature inherent to the wiring of its virulence networks.ResultsIn this study, we manually reconstructed the signalling and transcriptional regulatory networks of 12 acute (incl. pyocin and elastase) and 8 chronic virulence factors (incl. biofilm), and the 4 quorum sensing (QS) systems of P. aeruginosa. Using Boolean modelling (BM), we unveiled the important roles that stochasticity and node connectivity play in the networks’ inherent dynamicity and robustness. We showed that both the static interactions, as well as the time when the interactions take place, are important features in the QS network. In addition, we found that the virulence factors of the acute networks are under strict repression, or under an activation that is non-strict or oscillatory, while the chronic networks favour the repression of the virulence factor, with only moderate activation under certain conditions.ConclusionIn conclusion, our in silico-modelling framework provided us with a system-level view of the P. aeruginosa virulence and QS networks to gain new insights into the various mechanisms that support its pathogenicity and response to stressors targeting these networks. Thus, we suggest that BM provides an invaluable tool to guide the design of new treatments against P. aeruginosa.

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Intraspecies Signaling between Common Variants of Pseudomonas aeruginosa Increases Production of Quorum-Sensing-Controlled Virulence Factors

mBio ◽

10.1128/mbio.01865-20 ◽

2020 ◽

Vol 11 (4) ◽

Cited By ~ 2

Author(s):

Dallas L. Mould ◽

Nico J. Botelho ◽

Deborah A. Hogan

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Opportunistic Pathogen ◽

Loss Of Function ◽

Wild Type ◽

Chronic Infections ◽

Content Type ◽

Complex Interactions ◽

Natural Settings ◽

Citrate Release

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa damages hosts through the production of diverse secreted products, many of which are regulated by quorum sensing (QS). The lasR gene, which encodes a central QS regulator, is frequently mutated in clinical isolates from chronic infections, and loss of LasR function (LasR−) generally impairs the activity of downstream QS regulators RhlR and PqsR. We found that in cocultures containing LasR+ and LasR− strains, LasR− strains hyperproduce the RhlR/RhlI-regulated antagonistic factors pyocyanin and rhamnolipids in diverse models and media and in different strain backgrounds. Diffusible QS autoinducers produced by the wild type were not required for this effect. Using transcriptomics, genetics, and biochemical approaches, we uncovered a reciprocal interaction between wild-type and lasR mutant pairs wherein the iron-scavenging siderophore pyochelin produced by the lasR mutant induced citrate release and cross-feeding from the wild type. Citrate, a metabolite often secreted in low iron environments, stimulated RhlR signaling and RhlI levels in LasR−but not in LasR+ strains. These studies reveal the potential for complex interactions between recently diverged, genetically distinct isolates within populations from single chronic infections. IMPORTANCE Coculture interactions between lasR loss-of-function and LasR+ Pseudomonas aeruginosa strains may explain the worse outcomes associated with the presence of LasR− strains. More broadly, this report illustrates how interactions within a genotypically diverse population, similar to those that frequently develop in natural settings, can promote unpredictably high virulence factor production.

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Inhibition of quorum sensing in Pseudomonas aeruginosa by azithromycin and its effectiveness in urinary tract infections

Journal of Medical Microbiology ◽

10.1099/jmm.0.025387-0 ◽

2011 ◽

Vol 60 (3) ◽

pp. 300-306 ◽

Cited By ~ 62

Author(s):

Anju Bala ◽

Ravi Kumar ◽

Kusum Harjai

Keyword(s):

Pseudomonas Aeruginosa ◽

Urinary Tract ◽

Quorum Sensing ◽

Urinary Tract Infections ◽

Opportunistic Pathogen ◽

Signal Molecules ◽

Chronic Infections ◽

Beneficial Effects ◽

Tract Infections

Pseudomonas aeruginosa, an opportunistic pathogen, is the third most common pathogen associated with nosocomial urinary tract infections (UTIs). The virulence of this organism is due to its ability to produce quorum-sensing (QS) signal molecules and form biofilms. These biofilms are usually resistant to conventional antibiotics and host immune responses. Recently, beneficial effects of macrolides, especially azithromycin (AZM), have been shown in patients suffering from chronic infections caused by P. aeruginosa. These were due to anti-inflammatory and modulatory effects of AZM on the expression of virulence factors of this pathogen. The present study was designed to evaluate the potential of AZM to inhibit QS signal molecules and its ability to attenuate the virulence of P. aeruginosa in an experimental UTI model. Sub-MIC concentrations of AZM significantly inhibited the production of QS signals, swimming, swarming and twitching motilities, and biofilm formation in vitro. The therapeutic evaluation of AZM in this experimental UTI model showed complete clearance of the organisms from the mouse kidneys. The results of this study highlight the potential effectiveness of AZM in attenuating the virulence of P. aeruginosa in a UTI model.

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Heterogenous response to R-pyocin killing in populations of Pseudomonas aeruginosa sourced from cystic fibrosis lungs

10.1101/2020.08.05.238956 ◽

2020 ◽

Author(s):

Madeline Mei ◽

Jacob Thomas ◽

Stephen P. Diggle

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Genotypic Diversity ◽

Opportunistic Pathogen ◽

Chronic Infections ◽

Bacterial Populations ◽

Heterogeneous Populations ◽

Lung Infections ◽

The Impact ◽

Lps Binding

AbstractBacteriocins are proteinaceous antimicrobials produced by bacteria which are active against other strains of the same species. R-type pyocins are phage tail-like bacteriocins produced by Pseudomonas aeruginosa. Due to their anti-pseudomonal activity, R-pyocins have potential as therapeutics in infection. P. aeruginosa is a Gram-negative opportunistic pathogen and is particularly problematic for individuals with cystic fibrosis (CF). P. aeruginosa from CF lung infections develop increasing resistance to antibiotics, making new treatment approaches essential. P. aeruginosa populations become phenotypically and genotypically diverse during infection, however little is known of the efficacy of R-pyocins against heterogeneous populations. R-pyocins vary by subtype (R1-R5), distinguished by binding to different residues on the lipopolysaccharide (LPS). Each type varies in killing spectrum, and each strain produces only one R-type. To evaluate the prevalence of different R-types, we screened P. aeruginosa strains from the International Pseudomonas Consortium Database (IPCD) and from our biobank of CF strains. We found that (i) R1-types were the most prevalent R-type among strains from respiratory sources and (ii) isolates collected from the same patient have the same R-type. We then assessed the impact of diversity on R-pyocin susceptibility and found a heterogenous response to R-pyocins within populations, likely due to differences in the LPS core. Our work reveals that heterogeneous populations of microbes exhibit variable susceptibility to R-pyocins and highlights that there is likely heterogeneity in response to other types of LPS-binding antimicrobials, including phage.ImportanceR-pyocins have potential as alternative therapeutics against Pseudomonas aeruginosa in chronic infection, however little is known about the efficacy of R-pyocins in heterogeneous bacterial populations. P. aeruginosa is known to become resistant to multiple antibiotics, as well as evolve phenotypic and genotypic diversity over time; thus it is particularly difficult to eradicate in chronic cystic fibrosis (CF) lung infections. In this study, we found that P. aeruginosa populations from CF lungs maintain the same R-pyocin genotype but exhibit heterogeneity in susceptibility to R-pyocins from other strains. Our findings suggest there is likely heterogeneity in response to other types of LPS-binding antimicrobials, such as phage, highlighting the necessity of further studying the potential of LPS-binding antimicrobial particles as alternative therapies in chronic infections.

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Rhamnolipids stabilize quorum sensing mediated cooperation in Pseudomonas aeruginosa

FEMS Microbiology Letters ◽

10.1093/femsle/fnaa080 ◽

2020 ◽

Vol 367 (10) ◽

Cited By ~ 2

Author(s):

Rodolfo García-Contreras ◽

Daniel Loarca ◽

Caleb Pérez-González ◽

J Guillermo Jiménez-Cortés ◽

Abigail Gonzalez-Valdez ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Carbon Source ◽

Public Goods ◽

Sole Carbon Source ◽

Regulatory Genes ◽

Chronic Infections ◽

Toxic Metabolites ◽

Serial Cultivation ◽

Selection Of

ABSTRACT Pseudomonas aeruginosa is one of the main models to study social behaviors in bacteria since it synthesizes several exoproducts, including exoproteases and siderophores and release them to the environment. Exoproteases and siderophores are public goods that can be utilized by the individuals that produce them but also by non-producers, that are considered social cheaters. Molecularly exoprotease cheaters are mutants in regulatory genes such as lasR, and are commonly isolated from chronic infections and selected in the laboratory upon serial cultivation in media with protein as a sole carbon source. Despite that the production of exoproteases is exploitable, cooperators have also ways to restrict the growth and selection of social cheaters, for instance by producing toxic metabolites like pyocyanin. In this work, using bacterial competitions, serial cultivation and growth assays, we demonstrated that rhamnolipids which production is regulated by quorum sensing, selectively affect the growth of lasR mutants and are able to restrict social cheating, hence contributing to the maintenance of cooperation in Pseudomonas aeruginosa populations.

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Rapid diversification of Pseudomonas aeruginosa in cystic fibrosis lung-like conditions

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1721270115 ◽

2018 ◽

Vol 115 (42) ◽

pp. 10714-10719 ◽

Cited By ~ 20

Author(s):

Alana Schick ◽

Rees Kassen

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Chronic Infection ◽

Opportunistic Pathogen ◽

Chronic Infections ◽

Evolutionary Diversification ◽

Nutritional Conditions ◽

Patient Health ◽

Rapid Diversification

Chronic infection of the cystic fibrosis (CF) airway by the opportunistic pathogen Pseudomonas aeruginosa is the leading cause of morbidity and mortality for adult CF patients. Prolonged infections are accompanied by adaptation of P. aeruginosa to the unique conditions of the CF lung environment, as well as marked diversification of the pathogen into phenotypically and genetically distinct strains that can coexist for years within a patient. Little is known, however, about the causes of this diversification and its impact on patient health. Here, we show experimentally that, consistent with ecological theory of diversification, the nutritional conditions of the CF airway can cause rapid and extensive diversification of P. aeruginosa. Mucin, the substance responsible for the increased viscosity associated with the thick mucus layer in the CF airway, had little impact on within-population diversification but did promote divergence among populations. Furthermore, in vitro evolution recapitulated traits thought to be hallmarks of chronic infection, including reduced motility and increased biofilm formation, and the range of phenotypes observed in a collection of clinical isolates. Our results suggest that nutritional complexity and reduced dispersal can drive evolutionary diversification of P. aeruginosa independent of other features of the CF lung such as an active immune system or the presence of competing microbial species. We suggest that diversification, by generating extensive phenotypic and genetic variation on which selection can act, may be a key first step in the development of chronic infections.

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