scholarly journals Metabolic basis for the evolution of a common pathogenic Pseudomonas aeruginosa variant

2022 ◽  
Author(s):  
Dallas L Mould ◽  
Mirjana Stevanovic ◽  
Alix Ashare ◽  
Daniel Schultz ◽  
Deborah Hogan
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Metabolic Regulation ◽  
Severe Disease ◽  
Bacterial Pathogen ◽  
Lavage Fluid ◽  
Loss Of Function ◽  
Two Component System ◽  
Progression Of Disease ◽  
Metabolic Basis

Microbes frequently evolve in reproducible ways. Here, we show that differences in specific metabolic regulation explain the frequent presence of lasR loss-of-function mutations in the bacterial pathogen Pseudomonas aeruginosa. While LasR contributes to virulence, lasR mutants have been associated with more severe disease. A model based on the intrinsic growth kinetics for a wild type strain and its LasR– derivative, in combination with an experimental evolution based genetic screen and further genetics analyses, indicated that differences in metabolism were sufficient to explain the rise of these common mutant types. The evolution of LasR– lineages in laboratory and clinical isolates depended on activity of the two-component system CbrAB, which modulates substrate prioritization through the catabolite repression control pathway. LasR– lineages frequently arise in cystic fibrosis lung infections and their detection correlates with disease severity. Our analysis of bronchoalveolar lavage fluid metabolomes identified compounds that negatively correlate with lung function, and we show that these compounds support enhanced growth of LasR– cells in a CbrB-controlled manner. We propose that in vivo metabolomes are a major driver of pathogen evolution, which may influence the progression of disease and its treatment.

scholarly journals The rapid in vivo evolution of Pseudomonas aeruginosa in ventilator-associated pneumonia patients leads to attenuated virulence

Open Biology ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. 170029 ◽  
Author(s):  
Ke Wang ◽  
Yi-qiang Chen ◽  
May M. Salido ◽  
Gurjeet S. Kohli ◽  
Jin-liang Kong ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Opportunistic Pathogen ◽  
Ventilator Associated Pneumonia ◽  
Loss Of Function ◽  
Short Term ◽  
Airway Infections ◽  
Evolutionary Trajectories ◽  
Human Airways ◽  
Late Stages

Pseudomonas aeruginosa is an opportunistic pathogen that causes severe airway infections in humans. These infections are usually difficult to treat and associated with high mortality rates. While colonizing the human airways, P. aeruginosa could accumulate genetic mutations that often lead to its better adaptability to the host environment. Understanding these evolutionary traits may provide important clues for the development of effective therapies to treat P. aeruginosa infections. In this study, 25 P. aeruginosa isolates were longitudinally sampled from the airways of four ventilator-associated pneumonia (VAP) patients. Pacbio and Illumina sequencing were used to analyse the in vivo evolutionary trajectories of these isolates. Our analysis showed that positive selection dominantly shaped P. aeruginosa genomes during VAP infections and led to three convergent evolution events, including loss-of-function mutations of lasR and mpl , and a pyoverdine-deficient phenotype. Specifically, lasR encodes one of the major transcriptional regulators in quorum sensing, whereas mpl encodes an enzyme responsible for recycling cell wall peptidoglycan. We also found that P. aeruginosa isolated at late stages of VAP infections produce less elastase and are less virulent in vivo than their earlier isolated counterparts, suggesting the short-term in vivo evolution of P. aeruginosa leads to attenuated virulence.

scholarly journals Phage steering of antibiotic-resistance evolution in the bacterial pathogen, Pseudomonas aeruginosa

2020 ◽  
Vol 2020 (1) ◽  
pp. 148-157 ◽  
Author(s):  
James Gurney ◽  
Léa Pradier ◽  
Joanne S Griffin ◽  
Claire Gougat-Barbera ◽  
Benjamin K Chan ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Bacterial Pathogen ◽  
Antibiotic Sensitivity ◽  
Resistant Bacteria ◽  
Phage Resistance ◽  
Antibiotic Resistant ◽  
Trade Off

Abstract Background and objectives Antimicrobial resistance is a growing global concern and has spurred increasing efforts to find alternative therapeutics. Bacteriophage therapy has seen near constant use in Eastern Europe since its discovery over a century ago. One promising approach is to use phages that not only reduce bacterial pathogen loads but also select for phage resistance mechanisms that trade-off with antibiotic resistance—so called ‘phage steering’. Methodology Recent work has shown that the phage OMKO1 can interact with efflux pumps and in so doing select for both phage resistance and antibiotic sensitivity of the pathogenic bacterium Pseudomonas aeruginosa. We tested the robustness of this approach to three different antibiotics in vitro (tetracycline, erythromycin and ciprofloxacin) and one in vivo (erythromycin). Results We show that in vitro OMKO1 can reduce antibiotic resistance of P. aeruginosa (Washington PAO1) even in the presence of antibiotics, an effect still detectable after ca.70 bacterial generations in continuous culture with phage. Our in vivo experiment showed that phage both increased the survival times of wax moth larvae (Galleria mellonella) and increased bacterial sensitivity to erythromycin. This increased antibiotic sensitivity occurred both in lines with and without the antibiotic. Conclusions and implications Our study supports a trade-off between antibiotic resistance and phage sensitivity. This trade-off was maintained over co-evolutionary time scales even under combined phage and antibiotic pressure. Similarly, OMKO1 maintained this trade-off in vivo, again under dual phage/antibiotic pressure. Our findings have implications for the future clinical use of steering in phage therapies. Lay Summary: Given the rise of antibiotic-resistant bacterial infection, new approaches to treatment are urgently needed. Bacteriophages (phages) are bacterial viruses. The use of such viruses to treat infections has been in near-continuous use in several countries since the early 1900s. Recent developments have shown that these viruses are not only effective against routine infections but can also target antibiotic resistant bacteria in a novel, unexpected way. Similar to other lytic phages, these so-called ‘steering phages’ kill the majority of bacteria directly. However, steering phages also leave behind bacterial variants that resist the phages, but are now sensitive to antibiotics. Treatment combinations of these phages and antibiotics can now be used to greater effect than either one independently. We evaluated the impact of steering using phage OMKO1 and a panel of three antibiotics on Pseudomonas aeruginosa, an important pathogen in hospital settings and in people with cystic fibrosis. Our findings indicate that OMKO1, either alone or in combination with antibiotics, maintains antibiotic sensitivity both in vitro and in vivo, giving hope that phage steering will be an effective treatment option against antibiotic-resistant bacteria.

scholarly journals Capsule carbohydrate structure determines virulence in Acinetobacter baumannii

2021 ◽  
Vol 17 (2) ◽  
pp. e1009291
Author(s):  
Yuli Talyansky ◽  
Travis B. Nielsen ◽  
Jun Yan ◽  
Ulrike Carlino-Macdonald ◽  
Gisela Di Venanzio ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Bacterial Pathogen ◽  
Specific Gene ◽  
Dependent Manner ◽  
Bacterial Burden ◽  
Carbohydrate Structure ◽  
Loss Of Function ◽  
Capsule Assembly

Acinetobacter baumannii is a highly antibiotic-resistant bacterial pathogen for which novel therapeutic approaches are needed. Unfortunately, the drivers of virulence in A. baumannii remain uncertain. By comparing genomes among a panel of A. baumannii strains we identified a specific gene variation in the capsule locus that correlated with altered virulence. While less virulent strains possessed the intact gene gtr6, a hypervirulent clinical isolate contained a spontaneous transposon insertion in the same gene, resulting in the loss of a branchpoint in capsular carbohydrate structure. By constructing isogenic gtr6 mutants, we confirmed that gtr6-disrupted strains were protected from phagocytosis in vitro and displayed higher bacterial burden and lethality in vivo. Gtr6+ strains were phagocytized more readily and caused lower bacterial burden and no clinical illness in vivo. We found that the CR3 receptor mediated phagocytosis of gtr6+, but not gtr6-, strains in a complement-dependent manner. Furthermore, hypovirulent gtr6+ strains demonstrated increased virulence in vivo when CR3 function was abrogated. In summary, loss-of-function in a single capsule assembly gene dramatically altered virulence by inhibiting complement deposition and recognition by phagocytes across multiple A. baumannii strains. Thus, capsular structure can determine virulence among A. baumannii strains by altering bacterial interactions with host complement-mediated opsonophagocytosis.

scholarly journals MUC1 ectodomain is a flagellin-targeting decoy receptor and biomarker operative during Pseudomonas aeruginosa lung infection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Avelino C. Verceles ◽  
Pavan Bhat ◽  
Zain Nagaria ◽  
Destiny Martin ◽  
Harsh Patel ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bronchoalveolar Lavage Fluid ◽  
Wild Type Strain ◽  
Lavage Fluid ◽  
Airway Epithelial ◽  
Wild Type ◽  
Epithelial Surface ◽  
Decoy Receptor ◽  
Neu1 Sialidase

AbstractWe previously reported that flagellin-expressing Pseudomonas aeruginosa (Pa) provokes NEU1 sialidase-mediated MUC1 ectodomain (MUC1-ED) desialylation and MUC1-ED shedding from murine lungs in vivo. Here, we asked whether Pa in the lungs of patients with ventilator-associated pneumonia might also increase MUC1-ED shedding. The levels of MUC1-ED and Pa-expressed flagellin were dramatically elevated in bronchoalveolar lavage fluid (BALF) harvested from Pa-infected patients, and each flagellin level, in turn, predicted MUC1-ED shedding in the same patient. Desialylated MUC1-ED was only detected in BALF of Pa-infected patients. Clinical Pa strains increased MUC1-ED shedding from cultured human alveolar epithelia, and FlaA and FlaB flagellin-expressing strains provoked comparable levels of MUC1-ED shedding. A flagellin-deficient isogenic mutant generated dramatically reduced MUC1-ED shedding compared with the flagellin-expressing wild-type strain, and purified FlaA and FlaB recapitulated the effect of intact bacteria. Pa:MUC1-ED complexes were detected in the supernatants of alveolar epithelia exposed to wild-type Pa, but not to the flagellin-deficient Pa strain. Finally, human recombinant MUC1-ED dose-dependently disrupted multiple flagellin-driven processes, including Pa motility, Pa biofilm formation, and Pa adhesion to human alveolar epithelia, while enhancing human neutrophil-mediated Pa phagocytosis. Therefore, shed desialylated MUC1-ED functions as a novel flagellin-targeting, Pa-responsive decoy receptor that participates in the host response to Pa at the airway epithelial surface.

scholarly journals Role of Nod1 in Mucosal Dendritic Cells during Salmonella Pathogenicity Island 1-Independent Salmonella enterica Serovar Typhimurium Infection

2009 ◽  
Vol 77 (10) ◽  
pp. 4480-4486 ◽  
Author(s):  
Lionel Le Bourhis ◽  
Joao Gamelas Magalhaes ◽  
Thirumahal Selvanantham ◽  
Leonardo H. Travassos ◽  
Kaoru Geddes ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Lamina Propria ◽  
Salmonella Enterica ◽  
Severe Disease ◽  
Bacterial Pathogen ◽  
Critical Function ◽  
Intestinal Lamina Propria ◽  
Serovar Typhimurium

ABSTRACT Recent advances in immunology have highlighted the critical function of pattern-recognition molecules (PRMs) in generating the innate immune response to effectively target pathogens. Nod1 and Nod2 are intracellular PRMs that detect peptidoglycan motifs from the cell walls of bacteria once they gain access to the cytosol. Salmonella enterica serovar Typhimurium is an enteric intracellular pathogen that causes a severe disease in the mouse model. This pathogen resides within vacuoles inside the cell, but the question of whether cytosolic PRMs such as Nod1 and Nod2 could have an impact on the course of S. Typhimurium infection in vivo has not been addressed. Here, we show that deficiency in the PRM Nod1, but not Nod2, resulted in increased susceptibility toward a mutant strain of S. Typhimurium that targets directly lamina propria dendritic cells (DCs) for its entry into the host. Using this bacterium and bone marrow chimeras, we uncovered a surprising role for Nod1 in myeloid cells controlling bacterial infection at the level of the intestinal lamina propria. Indeed, DCs deficient for Nod1 exhibited impaired clearance of the bacteria, both in vitro and in vivo, leading to increased organ colonization and decreased host survival after oral infection. Taken together, these findings demonstrate a key role for Nod1 in the host response to an enteric bacterial pathogen through the modulation of intestinal lamina propria DCs.

scholarly journals Phospholipid peroxidation fuels ExoU phospholipase-dependent cell necrosis and supports Pseudomonas aeruginosa-driven pathology

2021 ◽  
Author(s):  
Salimata Bagayoko ◽  
Stephen Leon Icaza ◽  
Miriam Pinilla ◽  
Audrey Hessel ◽  
Karin Santoni ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Pathogen ◽  
Organ Damage ◽  
The Body ◽  
Cell Necrosis ◽  
Cellular Mechanisms ◽  
Dependent Cell

SummaryRegulated cell necrosis supports immune and anti-infectious strategies of the body; however, dysregulation of these processes drives pathological organ damage. Pseudomonas aeruginosa expresses a phospholipase, ExoU that triggers pathological host cell necrosis through a poorly characterized pathway. Here, we investigated the molecular and cellular mechanisms of ExoU-mediated necrosis. We show that cellular peroxidised phospholipids enhance ExoU phospholipase activity, which drives necrosis of immune and non-immune cells. Conversely, both the endogenous lipid peroxidation regulator GPX4 and the pharmacological inhibition of lipid peroxidation delay ExoU-dependent cell necrosis and improve bacterial elimination in vitro and in vivo. Our findings also pertain to the ExoU-related phospholipase from the bacterial pathogen Burkholderia thailandensis, suggesting that exploitation of peroxidised phospholipids might be a conserved virulence mechanism among various microbial phospholipases. Overall, our results identify an original lipid peroxidation-based virulence mechanism as a strong contributor of microbial phospholipase-driven pathology.

scholarly journals Epinecidin-1 Has Immunomodulatory Effects, Facilitating Its Therapeutic Use in a Mouse Model of Pseudomonas aeruginosa Sepsis

2014 ◽  
Vol 58 (8) ◽  
pp. 4264-4274 ◽  
Author(s):  
Chieh-Yu Pan ◽  
Jian-Chyi Chen ◽  
Jenn-Feng Sheen ◽  
Tai-Lang Lin ◽  
Jyh-Yih Chen
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mouse Model ◽  
Antimicrobial Properties ◽  
Bacterial Pathogen ◽  
Multidrug Resistant ◽  
Behavioral Effects ◽  
Immunomodulatory Effects ◽  
Kidney Toxicity ◽  
Content Type

ABSTRACTAntimicrobial peptides (AMPs) are garnering attention as possible alternatives to antibiotics. Here, we describe the antimicrobial properties of epinecidin-1 against a multidrug-resistant clinical isolate ofP. aeruginosa(P. aeruginosaR) and aP. aeruginosastrain from ATCC (P. aeruginosaATCC 19660)in vivo. The MICs of epinecidin-1 againstP. aeruginosaR andP. aeruginosaATCC 19660 were determined and compared with those of imipenem. Epinecidin-1 was found to be highly effective at combating peritonitis infection caused byP. aeruginosaR orP. aeruginosaATCC 19660 in mouse models, without inducing adverse behavioral effects or liver or kidney toxicity. Taken together, our results indicate that epinecidin-1 enhances the rate of survival of mice infected with the bacterial pathogenP. aeruginosathrough both antimicrobial and immunomodulatory effects.

scholarly journals Instantaneous Within-Patient Diversity of Pseudomonas aeruginosa Quorum-Sensing Populations from Cystic Fibrosis Lung Infections

2009 ◽  
Vol 77 (12) ◽  
pp. 5631-5639 ◽  
Author(s):  
Cara N. Wilder ◽  
Gopal Allada ◽  
Martin Schuster
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Loss Of Function ◽  
Selective Forces ◽  
Lung Infections

ABSTRACT In the opportunistic pathogen Pseudomonas aeruginosa, acyl-homoserine lactone (acyl-HSL) quorum sensing (QS) regulates biofilm formation and expression of many extracellular virulence factors. Curiously, QS-deficient variants, often carrying mutations in the central QS regulator LasR, are frequently isolated from infections, particularly from cystic fibrosis (CF) lung infections. Very little is known about the proportion and diversity of these QS variants in individual infections. Such information is desirable to better understand the selective forces that drive the evolution of QS phenotypes, including social cheating and innate (nonsocial) benefits. To obtain insight into the instantaneous within-patient diversity of QS, we assayed a panel of 135 concurrent P. aeruginosa isolates from eight different adult CF patients (9 to 20 isolates per patient) for various QS-controlled phenotypes. Most patients contained complex mixtures of QS-proficient and -deficient isolates. Among all patients, deficiency in individual phenotypes ranged from 0 to about 90%. Acyl-HSL, sequencing, and complementation analyses of variants with global loss-of-function phenotypes revealed dependency upon the central QS circuitry genes lasR, lasI, and rhlI. Deficient and proficient isolates were clonally related, implying evolution from a common ancestor in vivo. Our results show that the diversity of QS types is high within and among patients, suggesting diverse selection pressures in the CF lung. A single selective mechanism, be it of a social or nonsocial nature, is unlikely to account for such heterogeneity. The observed diversity also shows that conclusions about the properties of P. aeruginosa QS populations in individual CF infections cannot be drawn from the characterization of one or a few selected isolates.

scholarly journals The Drosophila melanogaster Toll Pathway Participates in Resistance to Infection by the Gram-Negative Human Pathogen Pseudomonas aeruginosa

2003 ◽  
Vol 71 (7) ◽  
pp. 4059-4066 ◽  
Author(s):  
Gee W. Lau ◽  
Boyan C. Goumnerov ◽  
Cynthia L. Walendziewicz ◽  
Jennifer Hewitson ◽  
Wenzhong Xiao ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Innate Immunity ◽  
Drosophila Melanogaster ◽  
Signaling Pathway ◽  
Virulence Factors ◽  
Loss Of Function ◽  
Gram Negative ◽  
Toll Signaling ◽  
Resistance To Infection

ABSTRACT Pseudomonas aeruginosa is a gram-negative pathogen that infects immunocompromised and cystic fibrosis patients. The molecular basis of the host-P. aeruginosa interaction and the effect of specific P. aeruginosa virulence factors on various components of the innate immunity pathways are largely unknown. We examine interactions between P. aeruginosa virulence factors and components of innate immunity response in the Drosophila melanogaster model system to reveal the importance of the Toll signaling pathway in resistance to infection by the P. aeruginosa human isolate PA14. Using the two PA14-isogenic mutants plcS and dsbA, we show that Drosophila loss-of-function mutants of Spatzle, the extracellular ligand of Toll, and Dorsal and Dif, two NF-κB-like transcription factors, allow increased P. aeruginosa infectivity within fly tissues. In contrast, a constitutively active Toll mutant and a loss-of-function mutant of Cactus, an IκB-like factor that inhibits the Toll signaling, reduce infectivity. Our finding that Dorsal activity is required to restrict P. aeruginosa infectivity in Drosophila provides direct in vivo evidence for Dorsal function in adult fly immunity. Additionally, our results provide the basis for future studies into interactions between P. aeruginosa virulence factors and components of the Toll signaling pathway, which is functionally conserved between flies and humans.

scholarly journals Host phospholipid peroxidation fuels ExoU-dependent cell necrosis and supports Pseudomonas aeruginosa-driven pathology

2021 ◽  
Vol 17 (9) ◽  
pp. e1009927
Author(s):  
Salimata Bagayoko ◽  
Stephen Adonai Leon-Icaza ◽  
Miriam Pinilla ◽  
Audrey Hessel ◽  
Karin Santoni ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Pathogen ◽  
Organ Damage ◽  
The Body ◽  
Cell Necrosis ◽  
Cellular Mechanisms ◽  
Dependent Cell

Regulated cell necrosis supports immune and anti-infectious strategies of the body; however, dysregulation of these processes drives pathological organ damage. Pseudomonas aeruginosa expresses a phospholipase, ExoU that triggers pathological host cell necrosis through a poorly characterized pathway. Here, we investigated the molecular and cellular mechanisms of ExoU-mediated necrosis. We show that cellular peroxidised phospholipids enhance ExoU phospholipase activity, which drives necrosis of immune and non-immune cells. Conversely, both the endogenous lipid peroxidation regulator GPX4 and the pharmacological inhibition of lipid peroxidation delay ExoU-dependent cell necrosis and improve bacterial elimination in vitro and in vivo. Our findings also pertain to the ExoU-related phospholipase from the bacterial pathogen Burkholderia thailandensis, suggesting that exploitation of peroxidised phospholipids might be a conserved virulence mechanism among various microbial phospholipases. Overall, our results identify an original lipid peroxidation-based virulence mechanism as a strong contributor of microbial phospholipase-driven pathology.

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