scholarly journals Impact of Pseudomonas aeruginosa quorum sensing signaling molecules on adhesion and inflammatory markers in endothelial cells

2018 ◽  
Vol 14 ◽  
pp. 2580-2588 ◽  
Author(s):  
Carmen Curutiu ◽  
Florin Iordache ◽  
Veronica Lazar ◽  
Aurelia Magdalena Pisoschi ◽  
Aneta Pop ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Endothelial Cells ◽  
Quorum Sensing ◽  
Inflammatory Response ◽  
Adhesion Molecules ◽  
Laboratory Strain ◽  
Homoserine Lactone ◽  
Signaling Molecules ◽  
Host Cells ◽  
Infectious Process

Pseudomonas aeruginosa relies on the quorum sensing (QS) signaling system as a central regulator mechanism of virulence expression that contributes to the formation and maintenance of biofilms and tolerance to conventional antimicrobials. QS Signaling molecules (QSSMs) may be recognized and may function also within the host cells, being potentially involved in the progression of the infectious process. In this study we evaluate the expression of adhesion and inflammatory molecules in endothelial cells treated with P. aeruginosa QSSMs, in order to bring new insights on the mechanisms involved in the interaction of P. aeruginosa with host cells during the infectious process. Endothelial cells were stimulated with 20 µM of main P. aeruginosa QSSMs (OdDHL = N-(3-oxododecanoyl)-L-homoserine lactone, C4HSL = N-butyryl-L-homoserine lactone, PQS = 2-heptyl-3-hydroxy-4(1H)-quinolone and HHQ = 2-heptyl-4-quinolone). Adherence to endothelial cells, inert substratum and biofilm formation was evaluated. The expression of adhesion molecules (VE-cadherin, PECAM-1, ICAM-1, and P-selectin) and inflammatory response molecules (IL-1β, IL-6, TNFα, TGFβ, and eNOS) was assessed by qRT-PCR and flow cytometry. Our results showed that bacterial adherence to inert substratum and biofilm were decreased in the presence of all tested QSSMs. The adherence index of PAO1 laboratory strain to host cells was decreased between 10–40% in the presence of QSSMs, as compared to untreated control. Expression of eukaryotic cells adhesion molecules ICAM-1 and P-selectin was stimulated by QSSMs, whereas VE-cadherin and PECAM-1 levels were increased only by C4HSL. The inflammatory response of endothelial cells was also modulated, as observed by the modified expression of IL-1β (for C4HSL, PQS and HHQ), IL-6 (for C4HSL and HHQ), TNFα (for C4HSL and HHQ), TGFβ, and eNOS factors. Our results demonstrate that the main pseudomonadal QSSMs differentially modulate endothelial cells adhesion and proinflammatory cytokine expression. These observations provide new insights in the mechanisms by which different QSSMs activate endothelial cells and modulate the infectious process, and support the importance of recent studies aiming to develop anti-QS therapeutic strategies to fight against P. aeruginosa infections.

scholarly journals Pseudomonas aeruginosa Increases Formation of Multidrug-Tolerant Persister Cells in Response to Quorum-Sensing Signaling Molecules

2010 ◽  
Vol 192 (7) ◽  
pp. 1946-1955 ◽  
Author(s):  
Nina Möker ◽  
Charles R. Dean ◽  
Jianshi Tao
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Bacterial Species ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Signaling Molecules ◽  
Persister Cells ◽  
E Coli ◽  
Underlying Mechanisms ◽  
Lethal Doses

ABSTRACT Bacterial persister cells constitute a small portion of a culture which is tolerant to killing by lethal doses of bactericidal antibiotics. These phenotypic variants are formed in numerous bacterial species, including those with clinical relevance like the opportunistic pathogen Pseudomonas aeruginosa. Although persisters are believed to contribute to difficulties in the treatment of many infectious diseases, the underlying mechanisms affecting persister formation are not well understood. Here we show that even though P. aeruginosa cultures have a significantly smaller fraction of multidrug-tolerant persister cells than cultures of Escherichia coli or Staphylococcus aureus, they can increase persister numbers in response to quorum-sensing-related signaling molecules. The phenazine pyocyanin (and the closely related molecule paraquat) and the acyl-homoserine lactone 3-OC12-HSL significantly increased the persister numbers in logarithmic P. aeruginosa PAO1 or PA14 cultures but not in E. coli or S. aureus cultures.

Expression of Pseudomonas aeruginosa exoS is controlled by quorum sensing and RpoS

Microbiology ◽  
2004 ◽  
Vol 150 (4) ◽  
pp. 843-851 ◽  
Author(s):  
Michael Hogardt ◽  
Maximilian Roeder ◽  
Anna Maria Schreff ◽  
Leo Eberl ◽  
Jürgen Heesemann
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Host Cells ◽  
Regulatory Control ◽  
Reasonable Assumption ◽  
Virulence Determinants ◽  
Exoenzyme S ◽  
Regulatory Cascade

In Pseudomonas aeruginosa, virulence determinants and biofilm formation are coordinated via a hierarchical quorum sensing cascade, which involves the transcriptional regulators LasR and RhlR and their cognate homoserine lactone activators C12-HSL [N-(3-oxododecanoyl)-l-homoserine lactone] and c4-hsl (n-butanoyl-l-homoserine lactone), which are produced by LasI and RhlI, respectively. The exoenzyme S regulon of P. aeruginosa, comprises genes for a type III secretion system and for four anti-host effector proteins (ExoS, T, U and Y), which are translocated into host cells. It is a reasonable assumption that this ExoS regulon should be downregulated in the biofilm growth state and thus should also be under the regulatory control of the Las/Rhl system. Therefore, an exoS′-gfp reporter construct was used, and the influence of the Las and Rhl quorum sensing systems and the effect of the stationary-phase sigma factor RpoS on regulation of the exoS gene was examined. Evidence is provided for downregulation of exoS during biofilm formation of P. aeruginosa PAO1. The rhlI mutant PDO100 and rhlR mutant PDO111, but not the lasI mutant PDO-JP1, showed approximately twofold upregulation of the exoS′-gfp reporter in comparison to PAO1. Upregulation of exoS′-gfp in the PDO100 mutant could be repressed to normal level by adding C4-HSL autoinducer, indicating a negative regulatory effect of RhlR/C4-HSL on exoS expression. As RhlR/C4-HSL is also involved in regulation of RpoS, the P. aeruginosa rpoS mutant SS24 was examined and the exoS′-gfp reporter was found to be fivefold upregulated in comparison to PAO1. For the first time evidence is reported for a regulatory cascade linking RhlR/RhlI and RpoS with the expression of the anti-host effector ExoS, part of the exoenzyme S regulon. Moreover, these data suggest that the exoenzyme S regulon may be downregulated in P. aeruginosa biofilms.

scholarly journals Revisiting the quorum-sensing hierarchy in Pseudomonas aeruginosa: the transcriptional regulator RhlR regulates LasR-specific factors

Microbiology ◽  
2009 ◽  
Vol 155 (3) ◽  
pp. 712-723 ◽  
Author(s):  
Valérie Dekimpe ◽  
Eric Déziel
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Transcriptional Regulator ◽  
Homoserine Lactone ◽  
The Other ◽  
Virulence Determinants ◽  
Late Stationary Phase ◽  
Regulatory Systems ◽  
Specific Factors

Pseudomonas aeruginosa uses the two major quorum-sensing (QS) regulatory systems las and rhl to modulate the expression of many of its virulence factors. The las system is considered to stand at the top of the QS hierarchy. However, some virulence factors such as pyocyanin have been reported to still be produced in lasR mutants under certain conditions. Interestingly, such mutants arise spontaneously under various conditions, including in the airways of cystic fibrosis patients. Using transcriptional lacZ reporters, LC/MS quantification and phenotypic assays, we have investigated the regulation of QS-controlled factors by the las system. Our results show that activity of the rhl system is only delayed in a lasR mutant, thus allowing the expression of multiple virulence determinants such as pyocyanin, rhamnolipids and C4-homoserine lactone (HSL) during the late stationary phase. Moreover, at this stage, RhlR is able to overcome the absence of the las system by activating specific LasR-controlled functions, including production of 3-oxo-C12-HSL and Pseudomonas quinolone signal (PQS). P. aeruginosa is thus able to circumvent the deficiency of one of its QS systems by allowing the other to take over. This work demonstrates that the QS hierarchy is more complex than the model simply presenting the las system above the rhl system.

scholarly journals Effects of Antibiotics on Quorum Sensing in Pseudomonas aeruginosa

2008 ◽  
Vol 52 (10) ◽  
pp. 3648-3663 ◽  
Author(s):  
Mette E. Skindersoe ◽  
Morten Alhede ◽  
Richard Phipps ◽  
Liang Yang ◽  
Peter O. Jensen ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factor ◽  
Dna Microarrays ◽  
Underlying Mechanism ◽  
Homoserine Lactone ◽  
Reverse Transcription Pcr ◽  
Animal Infection ◽  
Beneficial Action ◽  
Severe Infections

ABSTRACT During infection, Pseudomonas aeruginosa employs bacterial communication (quorum sensing [QS]) to coordinate the expression of tissue-damaging factors. QS-controlled gene expression plays a pivotal role in the virulence of P. aeruginosa, and QS-deficient mutants cause less severe infections in animal infection models. Treatment of cystic fibrosis (CF) patients chronically infected with P. aeruginosa with the macrolide antibiotic azithromycin (AZM) has been demonstrated to improve the clinical outcome. Several studies indicate that AZM may accomplish its beneficial action in CF patients by impeding QS, thereby reducing the pathogenicity of P. aeruginosa. This led us to investigate whether QS inhibition is a common feature of antibiotics. We present the results of a screening of 12 antibiotics for their QS-inhibitory activities using a previously described QS inhibitor selector 1 strain. Three of the antibiotics tested, AZM, ceftazidime (CFT), and ciprofloxacin (CPR), were very active in the assay and were further examined for their effects on QS-regulated virulence factor production in P. aeruginosa. The effects of the three antibiotics administered at subinhibitory concentrations were investigated by use of DNA microarrays. Consistent results from the virulence factor assays, reverse transcription-PCR, and the DNA microarrays support the finding that AZM, CFT, and CPR decrease the expression of a range of QS-regulated virulence factors. The data suggest that the underlying mechanism may be mediated by changes in membrane permeability, thereby influencing the flux of N-3-oxo-dodecanoyl-l-homoserine lactone.

Close-up on a bacterial informational war in the geocaulosphere

2020 ◽  
Vol 66 (7) ◽  
pp. 447-454 ◽  
Author(s):  
Andrea Chane ◽  
Yvann Bourigault ◽  
Mathilde Bouteiller ◽  
Yoan Konto-Ghiorghi ◽  
Annabelle Merieau ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Communication Systems ◽  
Cell Communication ◽  
Soft Rot ◽  
Homoserine Lactone ◽  
Signaling Molecules ◽  
Disease Symptoms ◽  
Reporter Strains ◽  
Bright Green ◽  
Bright Green Fluorescence

The geocaulosphere is home to microbes that establish communication between themselves and others that disrupt them. These cell-to-cell communication systems are based on the synthesis and perception of signaling molecules, of which the best known belong to the N-acyl-homoserine lactone (AHL) family. Among indigenous bacteria, certain Gram-positive actinobacteria can sense AHLs produced by soft-rot Gram-negative phytopathogens and can degrade the quorum-sensing AHL signals to impair the expression of virulence factors. We mimicked this interaction by introducing dual-color reporter strains suitable for monitoring both the location of the cells and their quorum-sensing and -quenching activities, in potato tubers. The exchange of AHL signals within the pathogen’s cell quorum was clearly detected by the presence of bright green fluorescence instead of blue in a portion of Pectobacterium-tagged cells. This phenomenon in Rhodococcus cells was accompanied by a change from red fluorescence to orange, showing that the disappearance of signaling molecules is due to rhodococcal AHL degradation rather than the inhibition of AHL production. Rhodococci are victorious in this fight for the control of AHL-based communication, as their jamming activity is powerful enough to prevent the onset of disease symptoms.

Cystathionine-β-synthase gene transfer and 3-deazaadenosine ameliorate inflammatory response in endothelial cells

2007 ◽  
Vol 293 (6) ◽  
pp. C1779-C1787 ◽  
Author(s):  
Utpal Sen ◽  
Neetu Tyagi ◽  
Munish Kumar ◽  
Karni S. Moshal ◽  
Walter E. Rodriguez ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Inflammatory Response ◽  
Protein Expression ◽  
Adhesion Molecules ◽  
Adhesion Molecule ◽  
Vascular Remodeling ◽  
Collagen Type ◽  
Gene Transfection ◽  
Collagen Type 1

Although elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associated with increased inflammation and vascular remodeling, the mechanism of Hcy-mediated inflammation and vascular remodeling is unclear. The matrix metalloproteinases (MMPs) and adhesion molecules play an important role in vascular remodeling. We hypothesized that HHcy induces inflammation by increasing adhesion molecules and matrix protein expression. Endothelial cells were supplemented with high methionine, and Hcy accumulation was measured by HPLC. Nitric oxide (NO) bioavailability was detected by a NO probe. The protein expression was measured by Western blot analysis. MMP-9 activity was detected by gelatin-gel zymography. We demonstrated that methionine supplement promoted upregulation of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) through increased Hcy accumulation. In addition, increased synthesis of collagen type-1 was also observed. MMP-9 gene expression and protein activity were increased in methionine supplement groups. 3-Deazaadenosine (DZA), an adenosine analogue, prevented high methionine-induced ICAM-1 and VCAM-1 expression and collagen type-1 synthesis. Transfection of endothelial cells with cystathionine-β-synthase (CBS) gene construct, which converts Hcy to cystathionine, reduced Hcy accumulation in high methionine-fed cells. CBS gene transfection reduced the inflammatory response, as evident by attenuated ICAM-1 and VCAM-1 expression. Furthermore, collagen type-1 expression and MMP-9 activity were dramatically attenuated with CBS gene transfection. These results suggested that methionine supplement increased Hcy accumulation, which was associated with inflammatory response and matrix remodeling such as collagen type-1 synthesis and MMP-9 activity. However, in vitro DZA and CBS gene therapy successfully treated the HHcy-induced inflammatory reaction in the methionine metabolism pathway.

scholarly journals Quorum-Sensing Genes in Pseudomonas aeruginosa Biofilms: Their Role and Expression Patterns

2001 ◽  
Vol 67 (4) ◽  
pp. 1865-1873 ◽  
Author(s):  
Teresa R. De Kievit ◽  
Richard Gillis ◽  
Steve Marx ◽  
Chris Brown ◽  
Barbara H. Iglewski
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Fluorescent Protein ◽  
Expression Patterns ◽  
Homoserine Lactone ◽  
Lower Percentage ◽  
Spatial Studies ◽  
Green Fluorescent ◽  
Biofilm Development

ABSTRACT Acylated homoserine lactone molecules are used by a number of gram-negative bacteria to regulate cell density-dependent gene expression by a mechanism known as quorum sensing (QS). InPseudomonas aeruginosa, QS or cell-to-cell signaling controls expression of a number of virulence factors, as well as biofilm differentiation. In this study, we investigated the role played by the las and rhl QS systems during the early stages of static biofilm formation when cells are adhering to a surface and forming microcolonies. These studies revealed a marked difference in biofilm formation between the PAO1 parent and the QS mutants when glucose, but not citrate, was used as the sole carbon source. To further elucidate the contribution of lasI andrhlI to biofilm maturation, we utilized fusions to unstable green fluorescent protein in concert with confocal microscopy to perform real-time temporal and spatial studies of these genes in a flowing environment. During the course of 8-day biofilm development,lasI expression was found to progressively decrease over time. Conversely, rhlI expression remained steady throughout biofilm development but occurred in a lower percentage of cells. Spatial analysis revealed that lasI andrhlI were maximally expressed in cells located at the substratum and that expression decreased with increasing biofilm height. Because QS was shown previously to be involved in biofilm differentiation, these findings have important implications for the design of biofilm prevention and eradication strategies.

scholarly journals Alginate Oligosaccharide-Induced Modification of the lasI-lasR and rhlI-rhlR Quorum-Sensing Systems in Pseudomonas aeruginosa

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Alison A. Jack ◽  
Saira Khan ◽  
Lydia C. Powell ◽  
Manon F. Pritchard ◽  
Konrad Beck ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Laser Scanning ◽  
Homoserine Lactone ◽  
Laser Scanning Microscopy ◽  
Extracellular Dna ◽  
Mass Spectrometry Analysis ◽  
Confocal Laser ◽  
Steric Interaction ◽  
Content Type

ABSTRACT Pseudomonas aeruginosa plays a major role in many chronic infections. Its ability to readily form biofilms contributes to its success as an opportunistic pathogen and its resistance/tolerance to antimicrobial/antibiotic therapy. A low-molecular-weight alginate oligomer (OligoG CF-5/20) derived from marine algae has previously been shown to impair motility in P. aeruginosa biofilms and disrupt pseudomonal biofilm assembly. As these bacterial phenotypes are regulated by quorum sensing (QS), we hypothesized that OligoG CF-5/20 may induce alterations in QS signaling in P. aeruginosa . QS regulation was studied by using Chromobacterium violaceum CV026 biosensor assays that showed a significant reduction in acyl homoserine lactone (AHL) production following OligoG CF-5/20 treatment (≥2%; P < 0.05). This effect was confirmed by liquid chromatography-mass spectrometry analysis of C 4 -AHL and 3-oxo-C 12 -AHL production (≥2%; P < 0.05). Moreover, quantitative PCR showed that reduced expression of both the las and rhl systems was induced following 24 h of treatment with OligoG CF-5/20 (≥0.2%; P < 0.05). Circular dichroism spectroscopy indicated that these alterations were not due to steric interaction between the AHL and OligoG CF-5/20. Confocal laser scanning microscopy (CLSM) and COMSTAT image analysis demonstrated that OligoG CF-5/20-treated biofilms had a dose-dependent decrease in biomass that was associated with inhibition of extracellular DNA synthesis (≥0.5%; P < 0.05). These changes correlated with alterations in the extracellular production of the pseudomonal virulence factors pyocyanin, rhamnolipids, elastase, and total protease ( P < 0.05). The ability of OligoG CF-5/20 to modify QS signaling in P. aeruginosa PAO1 may influence critical downstream functions such as virulence factor production and biofilm formation.

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