1
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Williamson DS, Smith GP, Mikkelsen GK, Jensen T, Acheson-Dossang P, Badolo L, Bedford ST, Chell V, Chen IJ, Dokurno P, Hentzer M, Newland S, Ray SC, Shaw T, Surgenor AE, Terry L, Wang Y, Christensen KV. Design and Synthesis of Pyrrolo[2,3- d]pyrimidine-Derived Leucine-Rich Repeat Kinase 2 (LRRK2) Inhibitors Using a Checkpoint Kinase 1 (CHK1)-Derived Crystallographic Surrogate. J Med Chem 2021; 64:10312-10332. [PMID: 34184879 DOI: 10.1021/acs.jmedchem.1c00720] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Inhibitors of leucine-rich repeat kinase 2 (LRRK2) and mutants, such as G2019S, have potential utility in Parkinson's disease treatment. Fragment hit-derived pyrrolo[2,3-d]pyrimidines underwent optimization using X-ray structures of LRRK2 kinase domain surrogates, based on checkpoint kinase 1 (CHK1) and a CHK1 10-point mutant. (2R)-2-Methylpyrrolidin-1-yl derivative 18 (LRRK2 G2019S cKi 0.7 nM, LE 0.66) was identified, with increased potency consistent with an X-ray structure of 18/CHK1 10-pt. mutant showing the 2-methyl substituent proximal to Ala147 (Ala2016 in LRRK2). Further structure-guided elaboration of 18 gave the 2-[(1,3-dimethyl-1H-pyrazol-4-yl)amino] derivative 32. Optimization of 32 afforded diastereomeric oxolan-3-yl derivatives 44 and 45, which demonstrated a favorable in vitro PK profile, although they displayed species disconnects in the in vivo PK profile, and a propensity for P-gp- and/or BCRP-mediated efflux in a mouse model. Compounds 44 and 45 demonstrated high potency and exquisite selectivity for LRRK2 and utility as chemical probes for the study of LRRK2 inhibition.
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Affiliation(s)
| | | | | | | | | | | | - Simon T Bedford
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Victoria Chell
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - I-Jen Chen
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Pawel Dokurno
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | | | - Samantha Newland
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Stuart C Ray
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Terry Shaw
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Allan E Surgenor
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Lindsey Terry
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
| | - Yikang Wang
- Vernalis (R&D) Ltd., Granta Park, Great Abington, Cambridge CB21 6GB, U.K
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2
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Thomsen K, Kobayashi O, Kishi K, Shirai R, Østrup Jensen P, Heydorn A, Hentzer M, Calum H, Christophersen L, Høiby N, Moser C. Animal models of chronic and recurrent Pseudomonas aeruginosa lung infection: significance of macrolide treatment. APMIS 2021; 130:458-476. [PMID: 34117660 DOI: 10.1111/apm.13161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 11/28/2022]
Abstract
Animal models of human diseases are invaluable and inevitable elements in identifying and testing novel treatments for serious diseases, including severe infections. Planning and conducting investigator-initiated human trials are generally accepted as being enormously challenging. In contrast, it is often underestimated how much planning, including background and modifying experiments, is needed to establish a relevant infectious disease animal model. However, representative animal infectious models, well designed to test generated hypotheses, are useful to improve our understanding of pathogenesis, virulence factors and host response and to identify novel treatment candidates and therapeutic strategies. Such results can subsequently proceed to clinical testing if suitable. The present review aims at presenting all the pulmonary Pseudomonas aeruginosa infectious models we have knowledge of and the detailed descriptions of established animal models in our laboratory focusing on macrolide therapy are presented.
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Affiliation(s)
- Kim Thomsen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Osamu Kobayashi
- Department of Infectious Diseases, National Cancer Center Hospital, Tokyo, Japan
| | - Kenji Kishi
- Oitaken Kouseiren Tsurumi Hospital, Tsurumi, Beppu City, Japan
| | - Ryo Shirai
- Department of Internal Medicine, Kawasaki Medical School, General Medical Center, Okayama, Japan
| | - Peter Østrup Jensen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Arne Heydorn
- Department of Endocrinology and Nephrology, Nordsjaellands Hospital, Hillerød, Denmark
| | - Morten Hentzer
- Department of Molecular Pharmacology, H. Lundbeck A/S, Copenhagen, Denmark
| | - Henrik Calum
- Department of Clinical Microbiology, Hvidovre Hospital, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lars Christophersen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
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3
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Williamson DS, Smith GP, Acheson-Dossang P, Bedford ST, Chell V, Chen IJ, Daechsel JCA, Daniels Z, David L, Dokurno P, Hentzer M, Herzig MC, Hubbard RE, Moore JD, Murray JB, Newland S, Ray SC, Shaw T, Surgenor AE, Terry L, Thirstrup K, Wang Y, Christensen KV. Design of Leucine-Rich Repeat Kinase 2 (LRRK2) Inhibitors Using a Crystallographic Surrogate Derived from Checkpoint Kinase 1 (CHK1). J Med Chem 2017; 60:8945-8962. [PMID: 29023112 DOI: 10.1021/acs.jmedchem.7b01186] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mutations in leucine-rich repeat kinase 2 (LRRK2), such as G2019S, are associated with an increased risk of developing Parkinson's disease. Surrogates for the LRRK2 kinase domain based on checkpoint kinase 1 (CHK1) mutants were designed, expressed in insect cells infected with baculovirus, purified, and crystallized. X-ray structures of the surrogates complexed with known LRRK2 inhibitors rationalized compound potency and selectivity. The CHK1 10-point mutant was preferred, following assessment of surrogate binding affinity with LRRK2 inhibitors. Fragment hit-derived arylpyrrolo[2,3-b]pyridine LRRK2 inhibitors underwent structure-guided optimization using this crystallographic surrogate. LRRK2-pSer935 HEK293 IC50 data for 22 were consistent with binding to Ala2016 in LRRK2 (equivalent to Ala147 in CHK1 10-point mutant structure). Compound 22 was shown to be potent, moderately selective, orally available, and brain-penetrant in wild-type mice, and confirmation of target engagement was demonstrated, with LRRK2-pSer935 IC50 values for 22 in mouse brain and kidney being 1.3 and 5 nM, respectively.
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Affiliation(s)
- Douglas S Williamson
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | | | | | - Simon T Bedford
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Victoria Chell
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - I-Jen Chen
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | | | - Zoe Daniels
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | | | - Pawel Dokurno
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | | | | | - Roderick E Hubbard
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Jonathan D Moore
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - James B Murray
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Samantha Newland
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Stuart C Ray
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Terry Shaw
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Allan E Surgenor
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Lindsey Terry
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Kenneth Thirstrup
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
| | - Yikang Wang
- Vernalis (R&D) Ltd. , Granta Park, Great Abington, Cambridge, CB21 6GB, United Kingdom
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4
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Smith GP, Badolo L, Chell V, Chen IJ, Christensen KV, David L, Daechsel JA, Hentzer M, Herzig MC, Mikkelsen GK, Watson SP, Williamson DS. The design and SAR of a novel series of 2-aminopyridine based LRRK2 inhibitors. Bioorg Med Chem Lett 2017; 27:4500-4505. [DOI: 10.1016/j.bmcl.2017.07.072] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/25/2017] [Accepted: 07/27/2017] [Indexed: 11/25/2022]
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5
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Bayer Andersen K, Leander Johansen J, Hentzer M, Smith GP, Dietz GPH. Protection of Primary Dopaminergic Midbrain Neurons by GPR139 Agonists Supports Different Mechanisms of MPP(+) and Rotenone Toxicity. Front Cell Neurosci 2016; 10:164. [PMID: 27445691 PMCID: PMC4923153 DOI: 10.3389/fncel.2016.00164] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/03/2016] [Indexed: 12/21/2022] Open
Abstract
The G-protein coupled receptor 139 (GPR139) is expressed specifically in the brain in areas of relevance for motor control. GPR139 function and signal transduction pathways are elusive, and results in the literature are even contradictory. Here, we examined the potential neuroprotective effect of GPR139 agonism in primary culture models of dopaminergic (DA) neuronal degeneration. We find that in vitro GPR139 agonists protected primary mesencephalic DA neurons against 1-methyl-4-phenylpyridinium (MPP(+))-mediated degeneration. Protection was concentration-dependent and could be blocked by a GPR139 antagonist. However, the protection of DA neurons was not found against rotenone or 6-hydroxydopamine (6-OHDA) mediated degeneration. Our results support differential mechanisms of toxicity for those substances commonly used in Parkinson's disease (PD) models and potential for GPR139 agonists in neuroprotection.
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Affiliation(s)
| | | | - Morten Hentzer
- Department of Molecular Screening, H. Lundbeck A/S Valby, Denmark
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6
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Wang J, Zhu LY, Liu Q, Hentzer M, Smith GP, Wang MW. High-throughput screening of antagonists for the orphan G-protein coupled receptor GPR139. Acta Pharmacol Sin 2015; 36:874-8. [PMID: 26027661 DOI: 10.1038/aps.2015.12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 01/27/2015] [Indexed: 11/09/2022] Open
Abstract
AIM To discover antagonists of the orphan G-protein coupled receptor GPR139 through high-throughput screening of a collection of diverse small molecules. METHODS Calcium mobilization assays were used to identify initial hits and for subsequent confirmation studies. RESULTS Five small molecule antagonists, representing 4 different scaffolds, were identified following high-throughput screening of 16 000 synthetic compounds. CONCLUSION The findings provide important tools for further study of this orphan G-protein coupled receptor.
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7
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Maeda K, Sugino H, Akazawa H, Amada N, Shimada J, Futamura T, Yamashita H, Ito N, McQuade RD, Mørk A, Pehrson AL, Hentzer M, Nielsen V, Bundgaard C, Arnt J, Stensbøl TB, Kikuchi T. Brexpiprazole I: In Vitro and In Vivo Characterization of a Novel Serotonin-Dopamine Activity Modulator. J Pharmacol Exp Ther 2014; 350:589-604. [DOI: 10.1124/jpet.114.213793] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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8
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Abstract
Our understanding of Parkinson's disease (PD) has been revolutionized by the discovery of disease-causing genetic mutations. The most common of these is the G2019S mutation in the LRRK2 kinase gene, which leads to increased kinase activity. However, the link between increased kinase activity and PD is unclear. Previously, we showed that dopaminergic expression of the human LRRK2-G2019S transgene in flies led to an activity-dependent loss of vision in older animals and we hypothesized that this may have been preceded by a failure to regulate neuronal activity correctly in younger animals. To test this hypothesis, we used a sensitive measure of visual function based on frequency-tagged steady-state visually evoked potentials. Spectral analysis allowed us to identify signals from multiple levels of the fly visual system and wild-type visual response curves were qualitatively similar to those from human cortex. Dopaminergic expression of hLRRK2-G2019S increased contrast sensitivity throughout the retinal network. To test whether this was due to increased kinase activity, we fed Drosophila with kinase inhibitors targeted at LRRK2. Contrast sensitivity in both day 1 and day 14 flies was normalized by a novel LRRK2 kinase inhibitor ‘BMPPB-32’. Biochemical and cellular assays suggested that BMPPB-32 would be a more specific kinase inhibitor than LRRK2-IN-1. We confirmed this in vivo, finding that dLRRK− null flies show large off-target effects with LRRK2-IN-1 but not BMPPB-32. Our data link the increased Kinase activity of the G2019S-LRRK2 mutation to neuronal dysfunction and demonstrate the power of the Drosophila visual system in assaying the neurological effects of genetic diseases and therapies.
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Affiliation(s)
| | - Kenneth V Christensen
- Neuroscience Drug Discovery DK, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark
| | - Garrick Paul Smith
- Neuroscience Drug Discovery DK, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark
| | - Morten Hentzer
- Neuroscience Drug Discovery DK, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark
| | | | | | - Alex R Wade
- Department of Psychology, University of York, YO1 5DD York, UK
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9
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Sams AG, Larsen K, Mikkelsen GK, Hentzer M, Christoffersen CT, Jensen KG, Frederiksen K, Bang-Andersen B. Hit-to-lead investigation of a series of novel combined dopamine D2 and muscarinic M1 receptor ligands with putative antipsychotic and pro-cognitive potential. Bioorg Med Chem Lett 2012; 22:5134-40. [PMID: 22677319 DOI: 10.1016/j.bmcl.2012.05.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 05/09/2012] [Accepted: 05/10/2012] [Indexed: 12/22/2022]
Abstract
We describe the discovery of a series of compounds based on 1-{3-[4-(2-oxo-2,3-dihydro-benzoimidazol-1-yl)-piperidin-1-yl]-propyl}-3,4-dihydro-1H-quinolin-2-one (3), showing combined D(2) receptor affinity and M(1) receptor agonism. Based on a strategy of controlling logP, we herein describe a hit-to-lead investigation with the aim of retaining the combined D(2)/M(1) profile, while removing the propensity of the compounds to inhibit the hERG channel, as well as at obtaining acceptable pharmacokinetic properties. Although a SAR was evident for all four parameters in question, it was not possible to separate hERG channel inhibition and D(2) receptor affinity by this effort; whilst it was feasible to obtain compounds with M(1) receptor agonism, acceptable clearance, and weak hERG inhibition.
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Affiliation(s)
- Anette Graven Sams
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S, Copenhagen-Valby, Denmark.
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10
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Shi F, Shen JK, Chen D, Fog K, Thirstrup K, Hentzer M, Karlsson JJ, Menon V, Jones KA, Smith KE, Smith G. Discovery and SAR of a Series of Agonists at Orphan G Protein-Coupled Receptor 139. ACS Med Chem Lett 2011; 2:303-6. [PMID: 24900311 DOI: 10.1021/ml100293q] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 02/12/2011] [Indexed: 01/16/2023] Open
Abstract
GPR139 is an orphan G-protein coupled receptor (GPCR) which is primarily expressed in the central nervous system (CNS). In order to explore the biological function of this receptor, selective tool compounds are required. A screening campaign identified compound 1a as a high potency GPR139 agonist with an EC50 = 39 nM in a calcium mobilization assay in CHO-K1 cells stably expressing the GPR139 receptor. In the absence of a known endogenous ligand, the maximum effect was set as 100% for 1a. Screening against 90 diverse targets revealed no cross-reactivity issues. Assessment of the pharmacokinetic properties showed limited utility as in vivo tool compound in rat with a poor whole brain exposure of 61 ng/g and a brain/plasma (b/p) ratio of 0.03. Attempts to identify a more suitable analogue identified the des-nitrogen analogue 1s with a reduced polar surface area of 76.7 Å(2) and an improved b/p ratio of 2.8. The whole brain exposure remained low at 95 ng/g due to a low plasma exposure.
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Affiliation(s)
- Feng Shi
- Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, 555
Zu-Chong-Zhi Road, Shanghai 201203, China
| | - Jing Kang Shen
- Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, 555
Zu-Chong-Zhi Road, Shanghai 201203, China
| | - Danqi Chen
- Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, 555
Zu-Chong-Zhi Road, Shanghai 201203, China
| | - Karina Fog
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S, 9 Ottiliavej, DK-2500
Copenhagen, Valby, Denmark
| | - Kenneth Thirstrup
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S, 9 Ottiliavej, DK-2500
Copenhagen, Valby, Denmark
| | - Morten Hentzer
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S, 9 Ottiliavej, DK-2500
Copenhagen, Valby, Denmark
| | - Jens-Jakob Karlsson
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S, 9 Ottiliavej, DK-2500
Copenhagen, Valby, Denmark
| | - Veena Menon
- Lundbeck Research USA, 215 College Road, Paramus, New Jersey 07652-1431,
United States
| | - Kenneth A. Jones
- Lundbeck Research USA, 215 College Road, Paramus, New Jersey 07652-1431,
United States
| | - Kelli E. Smith
- Lundbeck Research USA, 215 College Road, Paramus, New Jersey 07652-1431,
United States
| | - Garrick Smith
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S, 9 Ottiliavej, DK-2500
Copenhagen, Valby, Denmark
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11
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Sams AG, Hentzer M, Mikkelsen GK, Larsen K, Bundgaard C, Plath N, Christoffersen CT, Bang-Andersen B. Discovery of N-{1-[3-(3-oxo-2,3-dihydrobenzo[1,4]oxazin-4-yl)propyl]piperidin-4-yl}-2-phenylacetamide (Lu AE51090): an allosteric muscarinic M1 receptor agonist with unprecedented selectivity and procognitive potential. J Med Chem 2010; 53:6386-97. [PMID: 20684563 DOI: 10.1021/jm100697g] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The discovery and structure-activity relationship (SAR) of a series of allosteric muscarinic M(1) receptor agonists are described. Compound 17 (Lu AE51090) was identified as a representative compound from the series, based on its high selectivity as an agonist at the muscarinic M(1) receptor across a panel of muscarinic receptor subtypes. Furthermore, 17 displayed a high degree of selectivity when tested in a broad panel of G-protein-coupled receptors, ion channels, transporters, and enzymes, and 17 showed an acceptable pharmacokinetic profile and sufficient brain exposure in rodents in order to characterize the compound in vivo. Hence, in a rodent model of learning and memory, 17 reversed delay-induced natural forgetting, suggesting a procognitive potential of 17.
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Affiliation(s)
- Anette G Sams
- Medicinal Chemistry Research, Lundbeck Research Denmark, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark.
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12
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Yang L, Rybtke MT, Jakobsen TH, Hentzer M, Bjarnsholt T, Givskov M, Tolker-Nielsen T. Computer-aided identification of recognized drugs as Pseudomonas aeruginosa quorum-sensing inhibitors. Antimicrob Agents Chemother 2009; 53:2432-43. [PMID: 19364871 PMCID: PMC2687250 DOI: 10.1128/aac.01283-08] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 11/23/2008] [Accepted: 03/28/2009] [Indexed: 12/11/2022] Open
Abstract
Attenuation of Pseudomonas aeruginosa virulence by the use of small-molecule quorum-sensing inhibitors (referred to as the antipathogenic drug principle) is likely to play a role in future treatment strategies for chronic infections. In this study, structure-based virtual screening was used in a search for putative quorum-sensing inhibitors from a database comprising approved drugs and natural compounds. The database was built from compounds which showed structural similarities to previously reported quorum-sensing inhibitors, the ligand of the P. aeruginosa quorum-sensing receptor LasR, and a quorum-sensing receptor agonist. Six top-ranking compounds, all recognized drugs, were identified and tested for quorum-sensing-inhibitory activity. Three compounds, salicylic acid, nifuroxazide, and chlorzoxazone, showed significant inhibition of quorum-sensing-regulated gene expression and related phenotypes in a dose-dependent manner. These results suggest that the identified compounds have the potential to be used as antipathogenic drugs. Furthermore, the results indicate that structure-based virtual screening is an efficient tool in the search for novel compounds to combat bacterial infections.
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Affiliation(s)
- Liang Yang
- Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
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13
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Ritzén A, Sindet R, Hentzer M, Svendsen N, Brodbeck RM, Bundgaard C. Discovery of a potent and brain penetrant mGluR5 positive allosteric modulator. Bioorg Med Chem Lett 2009; 19:3275-8. [PMID: 19443216 DOI: 10.1016/j.bmcl.2009.04.095] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 04/19/2009] [Accepted: 04/20/2009] [Indexed: 11/30/2022]
Abstract
This Letter describes the discovery of a novel series of mGluR5 positive allosteric modulators (PAMs). The lead compound, 11c, exhibits excellent potency (EC(50)=30 nM) in vitro, and reaches high brain levels in both rats and mice after oral administration.
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Affiliation(s)
- Andreas Ritzén
- Medicinal Chemistry Research DK, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark.
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14
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Hoffmann N, Lee B, Hentzer M, Rasmussen TB, Song Z, Johansen HK, Givskov M, Høiby N. Azithromycin blocks quorum sensing and alginate polymer formation and increases the sensitivity to serum and stationary-growth-phase killing of Pseudomonas aeruginosa and attenuates chronic P. aeruginosa lung infection in Cftr(-/-) mice. Antimicrob Agents Chemother 2007; 51:3677-87. [PMID: 17620382 PMCID: PMC2043275 DOI: 10.1128/aac.01011-06] [Citation(s) in RCA: 195] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The consequences of O-acetylated alginate-producing Pseudomonas aeruginosa biofilms in the lungs of chronically infected cystic fibrosis (CF) patients are tolerance to both antibiotic treatments and effects on the innate and the adaptive defense mechanisms. In clinical trials, azithromycin (AZM) has been shown to improve the lung function of CF patients. The present study was conducted in accordance with previous in vitro studies suggesting that the effect of AZM may be the inhibition of alginate production, blockage of quorum sensing (QS), and increased sensitivity to hydrogen peroxide and the complement system. Moreover, we show that AZM may affect the polymerization of P. aeruginosa alginate by the incomplete precipitation of polymerized alginate and high levels of readily dialyzable uronic acids. In addition, we find that mucoid bacteria in the stationary growth phase became sensitive to AZM, whereas cells in the exponential phase did not. Interestingly, AZM-treated P. aeruginosa lasI mutants appeared to be particularly resistant to serum, whereas bacteria with a functional QS system did not. We show in a CF mouse model of chronic P. aeruginosa lung infection that AZM treatment results in the suppression of QS-regulated virulence factors, significantly improves the clearance of P. aeruginosa alginate biofilms, and reduces the severity of the lung pathology compared to that in control mice. We conclude that AZM attenuates the virulence of P. aeruginosa, impairs its ability to form fully polymerized alginate biofilms, and increases its sensitivity to complement and stationary-phase killing, which may explain the clinical efficacy of AZM.
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Affiliation(s)
- Nadine Hoffmann
- Department of Clinical Microbiology, Rigshospitalet, Institute for Medical Microbiology and Immunology, Panum Institute 24.1, University of Copenhagen, DK-2100, Copenhagen, Denmark.
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Shrout JD, Chopp DL, Just CL, Hentzer M, Givskov M, Parsek MR. The impact of quorum sensing and swarming motility on Pseudomonas aeruginosa biofilm formation is nutritionally conditional. Mol Microbiol 2006; 62:1264-77. [PMID: 17059568 DOI: 10.1111/j.1365-2958.2006.05421.x] [Citation(s) in RCA: 376] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of quorum sensing in Pseudomonas aeruginosa biofilm formation is unclear. Some researchers have shown that quorum sensing is important for biofilm development, while others have indicated it has little or no role. In this study, the contribution of quorum sensing to biofilm development was found to depend upon the nutritional environment. Depending upon the carbon source, quorum-sensing mutant strains (lasIrhlI and lasRrhlR) either exhibited a pronounced defect early in biofilm formation or formed biofilms identical to the wild-type strain. Quorum sensing was then shown to exert its nutritionally conditional control of biofilm development through regulation of swarming motility. Examination of pilA and fliM mutant strains further supported the role of swarming motility in biofilm formation. These data led to a model proposing that the prevailing nutritional conditions dictate the contributions of quorum sensing and swarming motility at a key juncture early in biofilm development.
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Affiliation(s)
- Joshua D Shrout
- Department of Microbiology, University of Iowa, Iowa City, IA, USA
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16
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Schreiber K, Boes N, Eschbach M, Jaensch L, Wehland J, Bjarnsholt T, Givskov M, Hentzer M, Schobert M. Anaerobic survival of Pseudomonas aeruginosa by pyruvate fermentation requires an Usp-type stress protein. J Bacteriol 2006; 188:659-68. [PMID: 16385055 PMCID: PMC1347276 DOI: 10.1128/jb.188.2.659-668.2006] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recently, we identified a pyruvate fermentation pathway in Pseudomonas aeruginosa sustaining anaerobic survival in the absence of alternative anaerobic respiratory and fermentative energy generation systems (M. Eschbach, K. Schreiber, K. Trunk, J. Buer, D. Jahn, and M. Schobert, J. Bacteriol. 186:4596-4604, 2004). Anaerobic long-term survival of P. aeruginosa might be essential for survival in deeper layers of a biofilm and the persistent infection of anaerobic mucus plaques in the cystic fibrosis lung. Proteome analysis of P. aeruginosa cells during a 7-day period of pyruvate fermentation revealed the induced synthesis of three enzymes involved in arginine fermentation, ArcA, ArcB, and ArcC, and the outer membrane protein OprL. Moreover, formation of two proteins of unknown function, PA3309 and PA4352, increased by factors of 72- and 22-fold, respectively. Both belong to the group of universal stress proteins (Usp). Long-term survival of a PA3309 knockout mutant by pyruvate fermentation was found drastically reduced. The oxygen-sensing regulator Anr controls expression of the PPA3309-lacZ reporter gene fusion after a shift to anaerobic conditions and further pyruvate fermentation. PA3309 expression was also found induced during the anaerobic and aerobic stationary phases. This aerobic stationary-phase induction is independent of the regulatory proteins Anr, RpoS, RelA, GacA, RhlR, and LasR, indicating a currently unknown mechanism of stationary-phase-dependent gene activation. PA3309 promoter activity was detected in the deeper layers of a P. aeruginosa biofilm using a PPA3309-gfp (green fluorescent protein gene) fusion and confocal laser-scanning microscopy. This is the first description of an Anr-dependent, anaerobically induced, and functional Usp-like protein in bacteria.
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Affiliation(s)
- Kerstin Schreiber
- Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany
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17
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Bjarnsholt T, Jensen PØ, Rasmussen TB, Christophersen L, Calum H, Hentzer M, Hougen HP, Rygaard J, Moser C, Eberl L, Høiby N, Givskov M. Garlic blocks quorum sensing and promotes rapid clearing of pulmonary Pseudomonas aeruginosa infections. Microbiology (Reading) 2005; 151:3873-3880. [PMID: 16339933 DOI: 10.1099/mic.0.27955-0] [Citation(s) in RCA: 305] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa is the predominant micro-organism of chronic lung infections in cystic fibrosis patients. P. aeruginosa colonizes the lungs by forming biofilm microcolonies throughout the lung. Quorum sensing (QS) renders the biofilm bacteria highly tolerant to otherwise lethal doses of antibiotics, and protects against the bactericidal activity of polymorphonuclear leukocytes (PMNs). It has been previously demonstrated that QS is inhibited by garlic extract. In this study, the synergistic effects of garlic and tobramycin, and PMNs activities have been evaluated. P. aeruginosa was grown in vitro in continuous-culture once-through flow chambers with and without garlic extract. The garlic-treated biofilms were susceptible to both tobramycin and PMN grazing. Furthermore, the PMNs showed an increase in respiratory burst activation, when incubated with the garlic-treated biofilm. Garlic extract was administered as treatment for a mouse pulmonary infection model. Mice were treated with garlic extract or placebo for 7 days, with the initial 2 days being prophylactic before P. aeruginosa was instilled in the left lung of the mice. Bacteriology, mortality, histopathology and cytokine production were used as indicators. The garlic treatment initially provoked a higher degree of inflammation, and significantly improved clearing of the infecting bacteria. The results indicate that a QS-inhibitory extract of garlic renders P. aeruginosa sensitive to tobramycin, respiratory burst and phagocytosis by PMNs, as well as leading to an improved outcome of pulmonary infections.
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Affiliation(s)
- Thomas Bjarnsholt
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Thomas B Rasmussen
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Lars Christophersen
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Henrik Calum
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Morten Hentzer
- Carlsberg Research Center, Biosector, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
| | - Hans-Petter Hougen
- Institute of Forensic Medicine, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Jørgen Rygaard
- Bartholin Instituttet, Kommune Hospitalet, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Leo Eberl
- Department of Microbiology, University of Zürich, CH-8008 Zürich, Switzerland
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Michael Givskov
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
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Bragonzi A, Worlitzsch D, Pier GB, Timpert P, Ulrich M, Hentzer M, Andersen JB, Givskov M, Conese M, Döring G. Nonmucoid Pseudomonas aeruginosa expresses alginate in the lungs of patients with cystic fibrosis and in a mouse model. J Infect Dis 2005; 192:410-9. [PMID: 15995954 PMCID: PMC1317300 DOI: 10.1086/431516] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Accepted: 03/23/2005] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND In patients with cystic fibrosis (CF), lung infection with mucoid Pseudomonas aeruginosa strains overexpressing the exopolysaccaride alginate is preceded by colonization with nonmucoid strains. We investigated the kinetics, impact of environmental signals, and genetics of P. aeruginosa alginate expression in a mouse model and in patients with CF. METHODS Using indirect immunofluorescence, microarray technology and real-time reverse-transcription polymerase chain reaction, we assessed alginate gene expression during aerobic and anaerobic growth of the nonmucoid strain PAO1 in vitro, in a mouse lung-infection model and in sputum specimens from patients with CF infected with nonmucoid or mucoid P. aeruginosa strains. RESULTS Anaerobic conditions increased the transcription of alginate genes in vitro and in murine lungs within 24 h. Alginate production by PAO1 in murine lungs and by nonmucoid P. aeruginosa strains in patients with CF was reversible after in vitro culture under aerobic conditions. A subpopulation of P. aeruginosa clones revealing stable alginate production was detected in murine lungs 2 weeks after infection. CONCLUSIONS Anaerobiosis and lung infection rapidly induce alginate production by gene regulation in nonmucoid P. aeruginosa. This trait may contribute to early persistence, leading to chronic P. aeruginosa infection once stable mucoid strains are generated.
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Affiliation(s)
- Alessandra Bragonzi
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
- Institute for Experimental Treatment of Cystic Fibrosis, HS Raffaele Scientific Institute, Milan, Italy
| | - Dieter Worlitzsch
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Gerald B. Pier
- Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Petra Timpert
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Martina Ulrich
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Morten Hentzer
- Center for Biomedical Microbiology, BioCentrum, Danish Technical University, Lyngby, Denmark
| | - Jens Bo Andersen
- Center for Biomedical Microbiology, BioCentrum, Danish Technical University, Lyngby, Denmark
| | - Michael Givskov
- Center for Biomedical Microbiology, BioCentrum, Danish Technical University, Lyngby, Denmark
| | - Massimo Conese
- Institute for Experimental Treatment of Cystic Fibrosis, HS Raffaele Scientific Institute, Milan, Italy
| | - Gerd Döring
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
- Reprints or correspondence: Prof. Gerd Döring, Institute of Medical Microbiology and Hygiene, Universitätsklinikum, Wilhelmstr. 31, D-72074 Tübingen, Germany ()
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Rasmussen TB, Skindersoe ME, Bjarnsholt T, Phipps RK, Christensen KB, Jensen PO, Andersen JB, Koch B, Larsen TO, Hentzer M, Eberl L, Hoiby N, Givskov M. Identity and effects of quorum-sensing inhibitors produced by Penicillium species. Microbiology (Reading) 2005; 151:1325-1340. [PMID: 15870443 DOI: 10.1099/mic.0.27715-0] [Citation(s) in RCA: 287] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Quorum sensing (QS) communication systems are thought to afford bacteria with a mechanism to strategically cause disease. One example is Pseudomonas aeruginosa, which infects immunocompromised individuals such as cystic fibrosis patients. The authors have previously documented that blockage of the QS systems not only attenuates Ps. aeruginosa but also renders biofilms highly susceptible to treatment with conventional antibiotics. Filamentous fungi produce a battery of secondary metabolites, some of which are already in clinical use as antimicrobial drugs. Fungi coexist with bacteria but lack active immune systems, so instead rely on chemical defence mechanisms. It was speculated that some of these secondary metabolites could interfere with bacterial QS communication. During a screening of 100 extracts from 50 Penicillium species, 33 were found to produce QS inhibitory (QSI) compounds. In two cases, patulin and penicillic acid were identified as being biologically active QSI compounds. Their effect on QS-controlled gene expression in Ps. aeruginosa was verified by DNA microarray transcriptomics. Similar to previously investigated QSI compounds, patulin was found to enhance biofilm susceptibility to tobramycin treatment. Ps. aeruginosa has developed QS-dependent mechanisms that block development of the oxidative burst in PMN neutrophils. Accordingly, when the bacteria were treated with either patulin or penicillic acid, the neutrophils became activated. In a mouse pulmonary infection model, Ps. aeruginosa was more rapidly cleared from the mice that were treated with patulin compared with the placebo group.
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Affiliation(s)
- Thomas Bovbjerg Rasmussen
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Mette E Skindersoe
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Thomas Bjarnsholt
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Richard K Phipps
- Center for Microbial Biotechnology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | | | - Peter Ostrup Jensen
- Department of Clinical Microbiology, Rigshospitalet, DK-2100, Copenhagen Ø, Denmark
| | - Jens Bo Andersen
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Birgit Koch
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Thomas Ostenfeld Larsen
- Center for Microbial Biotechnology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Morten Hentzer
- Carlsberg Research Center, Biosector, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
| | - Leo Eberl
- Department of Microbiology, University of Zürich, CH-8008 Zürich, Switzerland
| | - Niels Hoiby
- Department of Bacteriology, Institute of Medical Microbiology and Immunology, University of Copenhagen, Denmark
- Department of Clinical Microbiology, Rigshospitalet, DK-2100, Copenhagen Ø, Denmark
| | - Michael Givskov
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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20
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Bjarnsholt T, Jensen PØ, Burmølle M, Hentzer M, Haagensen JAJ, Hougen HP, Calum H, Madsen KG, Moser C, Molin S, Høiby N, Givskov M. Pseudomonas aeruginosa tolerance to tobramycin, hydrogen peroxide and polymorphonuclear leukocytes is quorum-sensing dependent. Microbiology 2005; 151:373-383. [PMID: 15699188 DOI: 10.1099/mic.0.27463-0] [Citation(s) in RCA: 330] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa is the predominant micro-organism of chronic lung infections in cystic fibrosis (CF) patients. P. aeruginosa colonizes the CF lungs by forming biofilm structures in the alveoli. In the biofilm mode of growth the bacteria are highly tolerant to otherwise lethal doses of antibiotics and are protected from bactericidal activity of polymorphonuclear leukocytes (PMNs). P. aeruginosa controls the expression of many of its virulence factors by means of a cell-cell communication system termed quorum sensing (QS). In the present report it is demonstrated that biofilm bacteria in which QS is blocked either by mutation or by administration of QS inhibitory drugs are sensitive to treatment with tobramycin and H2O2, and are readily phagocytosed by PMNs, in contrast to bacteria with functional QS systems. In contrast to the wild-type, QS-deficient biofilms led to an immediate respiratory-burst activation of the PMNs in vitro. In vivo QS-deficient mutants provoked a higher degree of inflammation. It is suggested that quorum signals and QS-inhibitory drugs play direct and opposite roles in this process. Consequently, the faster and highly efficient clearance of QS-deficient bacteria in vivo is probably a two-sided phenomenon: down regulation of virulence and activation of the innate immune system. These data also suggest that a combination of the action of PMNs and QS inhibitors along with conventional antibiotics would eliminate the biofilm-forming bacteria before a chronic infection is established.
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Affiliation(s)
- Thomas Bjarnsholt
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Mette Burmølle
- Department of Microbiology, University of Copenhagen, DK-1307 Copenhagen K, Denmark
| | | | - Janus A J Haagensen
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Hans Petter Hougen
- Institute of Forensic Medicine, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Henrik Calum
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Kit G Madsen
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Søren Molin
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark
| | - Michael Givskov
- Centre for Biomedical Microbiology, BioCentrum, Technical University of Denmark, DK-2800 Lyngby, Denmark
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21
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Hoffmann N, Rasmussen TB, Jensen PØ, Stub C, Hentzer M, Molin S, Ciofu O, Givskov M, Johansen HK, Høiby N. Novel mouse model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis. Infect Immun 2005; 73:2504-14. [PMID: 15784597 PMCID: PMC1087399 DOI: 10.1128/iai.73.4.2504-2514.2005] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Pseudomonas aeruginosa causes a chronic infection in the lungs of cystic fibrosis (CF) patients by establishing an alginate-containing biofilm. The infection has been studied in several animal models; however, most of the models required artificial embedding of the bacteria. We present here a new pulmonary mouse model without artificial embedding. The model is based on a stable mucoid CF sputum isolate (NH57388A) with hyperproduction of alginate due to a deletion in mucA and functional N-acylhomoserine lactone (AHL)-based quorum-sensing systems. Chronic lung infection could be established in both CF mice (Cftr(tmlUnc-/-)) and BALB/c mice, as reflected by the detection of a high number of P. aeruginosa organisms in the lung homogenates at 7 days postinfection and alginate biofilms, surrounded by polymorphonuclear leukocytes in the alveoli. In comparison, both an AHL-producing nonmucoid revertant (NH57388C) from the mucoid isolate (NH57388A) and a nonmucoid isolate (NH57388B) deficient in AHL were almost cleared from the lungs of the mice. This model, in which P. aeruginosa is protected against the defense system of the lung by alginate, is similar to the clinical situation. Therefore, the mouse model provides an improved method for evaluating the interaction between mucoid P. aeruginosa, the host, and antibacterial therapy.
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Affiliation(s)
- Nadine Hoffmann
- Department of Bacteriology, Institute for Medical Microbiology and Immunology, Panum Institute, University of Copenhagen, Copenhagen DK-2200, Denmark.
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22
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Rasmussen TB, Bjarnsholt T, Skindersoe ME, Hentzer M, Kristoffersen P, Köte M, Nielsen J, Eberl L, Givskov M. Screening for quorum-sensing inhibitors (QSI) by use of a novel genetic system, the QSI selector. J Bacteriol 2005; 187:1799-814. [PMID: 15716452 PMCID: PMC1063990 DOI: 10.1128/jb.187.5.1799-1814.2005] [Citation(s) in RCA: 391] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
With the widespread appearance of antibiotic-resistant bacteria, there is an increasing demand for novel strategies to control infectious diseases. Furthermore, it has become apparent that the bacterial life style also contributes significantly to this problem. Bacteria living in the biofilm mode of growth tolerate conventional antimicrobial treatments. The discovery that many bacteria use quorum-sensing (QS) systems to coordinate virulence and biofilm development has pointed out a new, promising target for antimicrobial drugs. We constructed a collection of screening systems, QS inhibitor (QSI) selectors, which enabled us to identify a number of novel QSIs among natural and synthetic compound libraries. The two most active were garlic extract and 4-nitro-pyridine-N-oxide (4-NPO). GeneChip-based transcriptome analysis revealed that garlic extract and 4-NPO had specificity for QS-controlled virulence genes in Pseudomonas aeruginosa. These two QSIs also significantly reduced P. aeruginosa biofilm tolerance to tobramycin treatment as well as virulence in a Caenorhabditis elegans pathogenesis model.
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Affiliation(s)
- Thomas Bovbjerg Rasmussen
- Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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23
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Danhorn T, Hentzer M, Givskov M, Parsek MR, Fuqua C. Phosphorus limitation enhances biofilm formation of the plant pathogen Agrobacterium tumefaciens through the PhoR-PhoB regulatory system. J Bacteriol 2004; 186:4492-501. [PMID: 15231781 PMCID: PMC438617 DOI: 10.1128/jb.186.14.4492-4501.2004] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The plant pathogen Agrobacterium tumefaciens forms architecturally complex biofilms on inert surfaces. Adherence of A. tumefaciens C58 was significantly enhanced under phosphate limitation compared to phosphate-replete conditions, despite slower overall growth under low-phosphate conditions. Replacement of Pi with sn-glycerol-3-phosphate and 2-aminoethylphosphonate yielded similar results. The increase in surface interactions under phosphate limitation was observed in both static culture and continuous-culture flow cells. Statistical analysis of confocal micrographs obtained from the flow cell biofilms revealed that phosphate limitation increased both the overall attached biomass and the surface coverage, whereas the maximum thickness of the biofilm was not affected. Functions encoded on the two large plasmids of A. tumefaciens C58, pTiC58 and pAtC58, were not required for the observed phosphate effect. The phosphate concentration at which increased attachment was observed triggered the phosphate limitation response, controlled in many bacteria by the two-component regulatory system PhoR-PhoB. The A. tumefaciens phoB and phoR orthologues could only be disrupted in the presence of plasmid-borne copies of the genes, suggesting that this regulatory system might be essential. Expression of the A. tumefaciens phoB gene from a tightly regulated inducible promoter, however, correlated with the amount of biofilm under both phosphate-limiting and nonlimiting conditions, demonstrating that components of the Pho regulon influence A. tumefaciens surface interactions.
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Affiliation(s)
- Thomas Danhorn
- Department of Biology, 1001 E. 3rd St., Jordan Hall 142, Indiana University, Bloomington, IN 47405-1847, USA
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24
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Stapper AP, Narasimhan G, Ohman DE, Barakat J, Hentzer M, Molin S, Kharazmi A, Høiby N, Mathee K. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation. J Med Microbiol 2004; 53:679-690. [PMID: 15184541 DOI: 10.1099/jmm.0.45539-0] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Extracellular polymers can facilitate the non-specific attachment of bacteria to surfaces and hold together developing biofilms. This study was undertaken to qualitatively and quantitatively compare the architecture of biofilms produced byPseudomonas aeruginosastrain PAO1 and its alginate-overproducing (mucA22) and alginate-defective (algD) variants in order to discern the role of alginate in biofilm formation. These strains, PAO1, Alg+PAOmucA22and Alg−PAOalgD, tagged with green fluorescent protein, were grown in a continuous flow cell system to characterize the developmental cycles of their biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (bip) and Community Statistics (comstat) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating that the production of alginate is not critical for biofilm formation. Observation over a period of 5 days indicated a three-stage development pattern consisting of initiation, establishment and maturation. Furthermore, this study showed that phenotypically distinguishable biofilms can be quantitatively differentiated.
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Affiliation(s)
- Andres Plata Stapper
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Giri Narasimhan
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Dennis E Ohman
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Johnny Barakat
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Morten Hentzer
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Søren Molin
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Arsalan Kharazmi
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Niels Høiby
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Kalai Mathee
- Department of Biological Sciences1 and School of Computer Science2, Florida International University, Miami, FL 33199, USA 3Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA 4Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark 5Department of Clinical Microbiology, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark
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25
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Abstract
Present-day treatment of chronic infections is based on compounds that aim to kill or inhibit growth of bacteria. Two problems are recognised to be intrinsically associated with this approach: (i) the frequently observed development of resistance to antimicrobial compounds; and (ii) the fact that all therapeutics are considerably less effective on bacteria growing as biofilms when compared with planktonic cells. The latter point is of particular importance as evidence has accumulated over the past few years that most chronic bacterial infections involve biofilms. The discovery of bacterial communication systems (quorum sensing systems) in Gram-negative bacteria which are believed to orchestrate important temporal events during the infectious process, including the production of virulence factors and the formation of biofilms, has afforded a novel opportunity to control the activity of infecting bacteria by other means than interfering with growth. Compounds that interfere with communication systems are present in nature. Such compounds should not only specifically attenuate the production of virulence factors but should also affect biofilm formation in a manner that is unlikely to pose a selective pressure for the development of resistant mutants.
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Affiliation(s)
- Morten Hentzer
- Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark
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Bagge N, Schuster M, Hentzer M, Ciofu O, Givskov M, Greenberg EP, Høiby N. Pseudomonas aeruginosa biofilms exposed to imipenem exhibit changes in global gene expression and beta-lactamase and alginate production. Antimicrob Agents Chemother 2004; 48:1175-87. [PMID: 15047518 PMCID: PMC375275 DOI: 10.1128/aac.48.4.1175-1187.2004] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lungs of cystic fibrosis (CF) patients are commonly colonized with Pseudomonas aeruginosa biofilms. Chronic endobronchial P. aeruginosa infections are impossible to eradicate with antibiotics, but intensive suppressive antibiotic therapy is essential to maintain the lung function of CF patients. The treatment often includes beta-lactam antibiotics. How these antibiotics influence gene expression in the surviving biofilm population of P. aeruginosa is not clear. Thus, we used the microarray technology to study the effects of subinhibitory concentrations of a beta-lactam antibiotic, imipenem, on gene expression in biofilm populations. Many genes showed small but statistically significant differential expression in response to imipenem. We identified 34 genes that were induced or repressed in biofilms exposed to imipenem more than fivefold compared to the levels of induction or repression for the controls. As expected, the most strongly induced gene was ampC, which codes for chromosomal beta-lactamase. We also found that genes coding for alginate biosynthesis were induced by exposure to imipenem. Alginate production is correlated to the development of impaired lung function, and P. aeruginosa strains isolated from chronically colonized lungs of CF patients are nearly always mucoid due to the overproduction of alginate. Exposure to subinhibitory concentrations of imipenem caused structural changes in the biofilm, e.g., an increased biofilm volume. Increased levels of alginate production may be an unintended adverse consequence of imipenem treatment in CF patients.
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Affiliation(s)
- Niels Bagge
- Department of Clinical Microbiology, Rigshospitalet, and Department of Bacteriology, Institute for Medical Microbiology and Immunology, Panum Institute, University of Copenhagen, Denmark.
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Bagge N, Hentzer M, Andersen JB, Ciofu O, Givskov M, Høiby N. Dynamics and spatial distribution of beta-lactamase expression in Pseudomonas aeruginosa biofilms. Antimicrob Agents Chemother 2004; 48:1168-74. [PMID: 15047517 PMCID: PMC375278 DOI: 10.1128/aac.48.4.1168-1174.2004] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of resistance to beta-lactam antibiotics is a problem in the treatment of chronic Pseudomonas aeruginosa infection in the lungs of patients with cystic fibrosis. The main resistance mechanism is high-level expression of the chromosomally encoded AmpC beta-lactamase of P. aeruginosa cells growing in biofilms. Several genes have been shown to influence the level of ampC expression, but little is known about the regulation of ampC expression in P. aeruginosa biofilms. To study the expression of ampC in P. aeruginosa biofilms, we constructed a reporter that consisted of the fusion of the ampC promoter to gfp(ASV) encoding an unstable version of the green fluorescent protein. In vitro biofilms of P. aeruginosa were exposed to the beta-lactam antibiotics imipenem and ceftazidime. Sub-MICs of imipenem significantly induced the monitor system of the biofilm bacteria in the peripheries of the microcolonies, but the centers of the microcolonies remained uninduced. However, the centers of the microcolonies were physiologically active, as shown by experiments with another monitor construction consisting of an arabinose-inducible promoter fused to gfp(ASV). The whole biofilm was induced in the presence of increased imipenem concentrations. Ceftazidime induced the monitor system of the biofilm bacteria as well, but only bacteria in the peripheries of the microcolonies were induced in the presence of even very high concentrations. The experiments illustrate for the first time the dynamic and spatial distributions of beta-lactamase induction in P. aeruginosa cells growing in biofilms. Thus, our experiments show that P. aeruginosa cells growing in biofilms constitute a heterogeneous population unit which may create different antibiotic-selective environments for the bacteria in the biofilm.
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Affiliation(s)
- Niels Bagge
- Department of Clinical Microbiology, Rigshospitalet, and Department of Bacteriology, Institute for Medical Microbiology and Immunology, Panum Institute, University of Copenhagen, Denmark.
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Wu H, Song Z, Hentzer M, Andersen JB, Molin S, Givskov M, Høiby N. Synthetic furanones inhibit quorum-sensing and enhance bacterial clearance in Pseudomonas aeruginosa lung infection in mice. J Antimicrob Chemother 2004; 53:1054-61. [PMID: 15117922 DOI: 10.1093/jac/dkh223] [Citation(s) in RCA: 338] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
INTRODUCTION Antibiotics are used to treat bacterial infections by killing the bacteria or inhibiting their growth, but resistance to antibiotics can develop readily. The discovery that bacterial quorum-sensing regulates bacterial virulence as well as the formation of biofilms opens up new ways to control certain bacterial infections. Furanone compounds capable of inhibiting bacterial quorum-sensing systems have been isolated from the marine macro alga Delisea pulchra. OBJECTIVES Two synthetic furanones were tested for their ability to attenuate bacterial virulence in the mouse models of chronic lung infection by targeting bacterial quorum-sensing without directly killing bacteria or inhibiting their growth. METHODS Study I. Mice with Escherichia coli MT102 [luxR-PluxI-gfp(ASV)] lung infection were injected intravenously with N-acyl homoserine lactones with or without furanones to test the interference of furanones with quorum-sensing. Study II. Mice with lung infection by Pseudomonas aeruginosa PAO1 [dsred, lasR-PlasB-gfp(ASV)] were injected intravenously with furanones to evaluate their inhibiting effects on quorum-sensing. Study III. Mice with P. aeruginosa PAO1 lung infection were treated with different doses of furanones to evaluate the therapeutic effects of furanones on the lung infection. RESULTS Furanones successfully interfered with N-acyl homoserine lactone and suppressed bacterial quorum-sensing in lungs, which resulted in decreases in expression of green fluorescent protein. Furanones accelerated lung bacterial clearance, and reduced the severity of lung pathology. In a lethal P. aeruginosa lung infection, treatment with furanone significantly prolonged the survival time of the mice. CONCLUSION Synthetic furanone compounds inhibited bacterial quorum-sensing in P. aeruginosa and exhibited favourable therapeutic effects on P. aeruginosa lung infection.
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Affiliation(s)
- H Wu
- Department of Clinical Microbiology, University Hospital of Copenhagen (Rigshospitalet), Juliane Marie Vej 22, Copenhagen Ø, DK-2100.
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Abstract
Traditional treatment of infectious diseases is based on compounds that aim to kill or inhibit bacterial growth. A major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. The discovery of bacterial-communication systems (quorum-sensing systems), which orchestrate important temporal events during the infection process, has afforded a novel opportunity to ameliorate bacterial infection by means other than growth inhibition. Compounds able to override bacterial signaling are present in nature. Herein we discuss the known signaling mechanisms and potential antipathogenic drugs that specifically target quorum-sensing systems in a manner unlikely to pose a selective pressure for the development of resistant mutants.
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Affiliation(s)
- Morten Hentzer
- Center for Biomedical Microbiology, BioCentrum, Building 301, Technical University of Denmark, DK-2800 Lyngby, Denmark.
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30
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Arevalo-Ferro C, Hentzer M, Reil G, Görg A, Kjelleberg S, Givskov M, Riedel K, Eberl L. Identification of quorum-sensing regulated proteins in the opportunistic pathogenPseudomonas aeruginosaby proteomics. Environ Microbiol 2003; 5:1350-69. [PMID: 14641579 DOI: 10.1046/j.1462-2920.2003.00532.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Gram-negative bacterium Pseudomonas aeruginosa is an opportunistic human pathogen which is responsible for severe nosocomial infections in immunocompromised patients and is the major pathogen in cystic fibrosis. The bacterium utilizes two interrelated quorum-sensing (QS) systems, which rely on N-acyl-homoserine lactone (AHL) signal molecules, to control the expression of virulence factors and biofilm development. In this study, we compared the protein patterns of the intracellular, extracellular and surface protein fractions of the PAO1 parent strain with those of an isogenic lasI rhlI double mutant by means of two-dimensional gel electrophoresis (2-DE). This analysis showed that the intensities of 23.7% of all detected protein spots differed more than 2.5-fold between the two strains. We only considered those protein spots truly QS regulated that were changed in the mutant in the absence of signal molecules but were rescued to the wild-type situation when the medium was supplemented with AHLs. These protein spots were characterized by MALDI-TOF peptide mapping. Twenty-seven proteins were identified that were previously reported to be AHL controlled, among them several well-characterized virulence factors. For one of the identified proteins, the serine protease PrpL, a biochemical assay was established to verify that expression of this factor is indeed QS regulated. Furthermore, it is shown that the quorum-sensing blocker C-30 specifically interferes with the expression of 67% of the AHL-controlled protein spots of the surface fraction, confirming the high specificity of the compound. Importantly, 20 novel QS-regulated proteins were identified, many of which are involved in iron utilization, suggesting a link between quorum sensing and the iron regulatory system. Two of these proteins, PhuR and HasAp, are components of the two distinct haem-uptake systems present in P. aeruginosa. In agreement with the finding that both proteins are positively regulated by the QS cascade, we show that the lasI rhlI double mutant grows poorly with haemoglobin as the only iron source when compared with the wild type. These results add haemoglobin utilization to the list of phenotypes controlled through QS in P. aeruginosa. The surprisingly high number of AHL-regulated proteins relative to the number of regulated genes suggests that quorum-sensing control also operates via post-transcriptional mechanisms. To strengthen this hypothesis we investigated the role of quorum sensing in the post-translational modification of HasAp, an extracellular protein required for the uptake of free and haemoglobin-bound haem.
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Affiliation(s)
- Catalina Arevalo-Ferro
- Department of Microbiology, Technical University of Munich, Am Hochanger 4, D-85350 Freising, Germany
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31
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Abstract
Traditional treatment of infectious diseases is based on compounds that aim to kill or inhibit bacterial growth. A major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. The discovery of bacterial-communication systems (quorum-sensing systems), which orchestrate important temporal events during the infection process, has afforded a novel opportunity to ameliorate bacterial infection by means other than growth inhibition. Compounds able to override bacterial signaling are present in nature. Herein we discuss the known signaling mechanisms and potential antipathogenic drugs that specifically target quorum-sensing systems in a manner unlikely to pose a selective pressure for the development of resistant mutants.
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Affiliation(s)
- Morten Hentzer
- Center for Biomedical Microbiology, BioCentrum, Building 301, Technical University of Denmark, DK-2800 Lyngby, Denmark.
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32
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Hentzer M, Wu H, Andersen JB, Riedel K, Rasmussen TB, Bagge N, Kumar N, Schembri MA, Song Z, Kristoffersen P, Manefield M, Costerton JW, Molin S, Eberl L, Steinberg P, Kjelleberg S, Høiby N, Givskov M. Attenuation of Pseudomonas aeruginosa virulence by quorum sensing inhibitors. EMBO J 2003; 22:3803-15. [PMID: 12881415 PMCID: PMC169039 DOI: 10.1093/emboj/cdg366] [Citation(s) in RCA: 958] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Traditional treatment of infectious diseases is based on compounds that kill or inhibit growth of bacteria. A major concern with this approach is the frequent development of resistance to antibiotics. The discovery of communication systems (quorum sensing systems) regulating bacterial virulence has afforded a novel opportunity to control infectious bacteria without interfering with growth. Compounds that can override communication signals have been found in the marine environment. Using Pseudomonas aeruginosa PAO1 as an example of an opportunistic human pathogen, we show that a synthetic derivate of natural furanone compounds can act as a potent antagonist of bacterial quorum sensing. We employed GeneChip microarray technology to identify furanone target genes and to map the quorum sensing regulon. The transcriptome analysis showed that the furanone drug specifically targeted quorum sensing systems and inhibited virulence factor expression. Application of the drug to P.aeruginosa biofilms increased bacterial susceptibility to tobramycin and SDS. In a mouse pulmonary infection model, the drug inhibited quorum sensing of the infecting bacteria and promoted their clearance by the mouse immune response.
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Affiliation(s)
- Morten Hentzer
- BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark
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33
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Bagge N, Ciofu O, Hentzer M, Campbell JIA, Givskov M, Høiby N. Constitutive high expression of chromosomal beta-lactamase in Pseudomonas aeruginosa caused by a new insertion sequence (IS1669) located in ampD. Antimicrob Agents Chemother 2002; 46:3406-11. [PMID: 12384343 PMCID: PMC128714 DOI: 10.1128/aac.46.11.3406-3411.2002] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The expression of chromosomal AmpC beta-lactamase in Pseudomonas aeruginosa is negatively regulated by the activity of an amidase, AmpD. In the present study we examined resistant clinical P. aeruginosa strains and several resistant variants isolated from in vivo and in vitro biofilms for mutations in ampD to find evidence for the genetic changes leading to high-level expression of chromosomal beta-lactamase. A new insertion sequence, IS1669, was found located in the ampD genes of two clinical P. aeruginosa isolates and several biofilm-isolated variants. The presence of IS1669 in ampD resulted in the expression of high levels of AmpC beta-lactamase. Complementation of these isolates with ampD from the reference P. aeruginosa strain PAO1 caused a dramatic decrease in the expression of AmpC beta-lactamase and a parallel decrease of the MIC of ceftazidime to a level comparable to that of PAO1. One highly resistant, constitutive beta-lactamase-producing variant contained no mutations in ampD, but a point mutation was observed in ampR, resulting in an Asp-135-->Asn change. An identical mutation of AmpR in Enterobacter cloacae has been reported to cause a 450-fold higher AmpC expression. However, in many of the isolates expressing high levels of chromosomal beta-lactamase, no changes were found in either ampD, ampR, or in the promoter region of ampD, ampR, or ampC. Our results suggest that multiple pathways may exist leading to increased antimicrobial resistance due to chromosomal beta-lactamase.
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Affiliation(s)
- Niels Bagge
- Institute of Medical Microbiology and Immunology, Panum Institute, University of Copenhagen, Denmark.
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34
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Laux DC, Corson JM, Givskov M, Hentzer M, Møller A, Wosencroft KA, Olson JC, Krogfelt KA, Goldberg JB, Cohen PS. Lysophosphatidic acid inhibition of the accumulation of Pseudomonas aeruginosa PAO1 alginate, pyoverdin, elastase and LasA. Microbiology (Reading) 2002; 148:1709-1723. [PMID: 12055291 DOI: 10.1099/00221287-148-6-1709] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The pathogenesis of Pseudomonas aeruginosa is at least partially attributable to its ability to synthesize and secrete the siderophore pyoverdin and the two zinc metalloproteases elastase and LasA, and its ability to form biofilms in which bacterial cells are embedded in an alginate matrix. In the present study, a lysophospholipid, 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphate [also called monopalmitoylphosphatidic acid (MPPA)], which accumulates in inflammatory exudates, was shown to inhibit the extracellular accumulation of P. aeruginosa PAO1 alginate, elastase, LasA protease and the siderophore pyoverdin. MPPA also inhibited biofilm formation. The inhibitory effects of MPPA occur independently of rpoS expression and without affecting the accumulation of the autoinducers N-(3-oxododecanoyl) homoserine lactone and N-butyryl-L-homoserine lactone, and may be due, at least in part, to the ability of MPPA to bind divalent cations.
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Affiliation(s)
- David C Laux
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA1
| | - Joy M Corson
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA1
| | - Michael Givskov
- Biocentrum, Bldg 301, Technical University of Denmark, DK-2800 Lyngby, Denmark2
| | - Morten Hentzer
- Biocentrum, Bldg 301, Technical University of Denmark, DK-2800 Lyngby, Denmark2
| | - Annette Møller
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA1
| | - Kathleen A Wosencroft
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA1
| | - Joan C Olson
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, USA3
| | - Karen A Krogfelt
- Department of Gastrointestinal Infections, Statens Serum Institut, DK 2300 Copenhagen, Denmark4
| | - Joanna B Goldberg
- Department of Microbiology, University of Virginia, Health Sciences Center, Charlottesville, VA 22908, USA5
| | - Paul S Cohen
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA1
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35
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Heydorn A, Ersbøll B, Kato J, Hentzer M, Parsek MR, Tolker-Nielsen T, Givskov M, Molin S. Statistical analysis of Pseudomonas aeruginosa biofilm development: impact of mutations in genes involved in twitching motility, cell-to-cell signaling, and stationary-phase sigma factor expression. Appl Environ Microbiol 2002; 68:2008-17. [PMID: 11916724 PMCID: PMC123874 DOI: 10.1128/aem.68.4.2008-2017.2002] [Citation(s) in RCA: 233] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Four strains of Pseudomonas aeruginosa (wild type, Delta(pil)HIJK mutant, lasI mutant, and rpoS mutant) were genetically tagged with the green fluorescent protein, and the development of flow chamber-grown biofilms by each of them was investigated by confocal laser scanning microscopy. The structural developments of the biofilms were quantified by the computer program COMSTAT (A. Heydorn, A. T. Nielsen, M. Hentzer, C. Sternberg, M. Givskov, B. K. Ersbøll, and S. Molin, Microbiology 146:2395-2407, 2000). Two structural key variables, average thickness and roughness, formed the basis for an analysis of variance model comprising the four P. aeruginosa strains, five time points (55, 98, 146, 242, and 314 h), and three independent rounds of biofilm experiments. The results showed that the wild type, the Delta(pil)HIJK mutant, and the rpoS mutant display conspicuously different types of temporal biofilm development, whereas the lasI mutant was indistinguishable from the wild type at all time points. The wild type and the lasI mutant formed uniform, densely packed biofilms. The rpoS mutant formed densely packed biofilms that were significantly thicker than those of the wild type, whereas the Delta(pil)HIJK mutant formed distinct microcolonies that were regularly spaced and almost uniform in size. The results are discussed in relation to the current model of P. aeruginosa biofilm development.
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Affiliation(s)
- Arne Heydorn
- Section of Molecular Microbiology, The Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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36
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Affiliation(s)
- Morten Hentzer
- Molecular Microbiology, Technical University of Denmark, Lyngby, Denmark
| | - Michael Givskov
- Molecular Microbiology, Technical University of Denmark, Lyngby, Denmark
| | - Matthew R. Parsek
- Department of Civil Engineering, Northwestern University, Evanston, IL
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Olsen JA, Severinsen R, Rasmussen TB, Hentzer M, Givskov M, Nielsen J. Synthesis of new 3- and 4-substituted analogues of acyl homoserine lactone quorum sensing autoinducers. Bioorg Med Chem Lett 2002; 12:325-8. [PMID: 11814788 DOI: 10.1016/s0960-894x(01)00756-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The quorum sensing mechanism in Gram-negative bacteria uses small intercellular signal molecules, N-acyl-homoserine lactones (AHLs), to control transcription of specific genes in relation to population density. In this communication, we describe the parallel synthesis of new AHL analogues, in which substituents have been introduced into the 3- and 4-positions of the lactone ring. These analogues have been screened for their ability to activate and inhibit a Vibrio fischeri LuxI/LuxR-derived quorum sensing reporter system.
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Affiliation(s)
- J A Olsen
- Department of Chemistry, Bld. 207, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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38
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Hentzer M, Riedel K, Rasmussen TB, Heydorn A, Andersen JB, Parsek MR, Rice SA, Eberl L, Molin S, Høiby N, Kjelleberg S, Givskov M. Inhibition of quorum sensing in Pseudomonas aeruginosa biofilm bacteria by a halogenated furanone compound. Microbiology 2002; 148:87-102. [PMID: 11782502 DOI: 10.1099/00221287-148-1-87] [Citation(s) in RCA: 665] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Novel molecular tools have been constructed which allow for in situ detection of N-acyl homoserine lactone (AHL)-mediated quorum sensing in Pseudomonas aeruginosa biofilms. The reporter responds to AHL activation of LasR by expression of an unstable version of the green-fluorescent protein (Gfp). Gfp-based reporter technology has been applied for non-destructive, single-cell-level detection of quorum sensing in laboratory-based P. aeruginosa biofilms. It is reported that a synthetic halogenated furanone compound, which is a derivative of the secondary metabolites produced by the Australian macroalga Delisea pulchra, is capable of interfering with AHL-mediated quorum sensing in P. aeruginosa. It is demonstrated that the furanone compound specifically represses expression of a PlasB-gfp reporter fusion without affecting growth or protein synthesis. In addition, it reduces the production of important virulence factors, indicating a general effect on target genes of the las quorum sensing circuit. The furanone was applied to P. aeruginosa biofilms established in biofilm flow chambers. The Gfp-based analysis reveals that the compound penetrates microcolonies and blocks cell signalling and quorum sensing in most biofilm cells. The compound did not affect initial attachment to the abiotic substratum. It does, however, affect the architecture of the biofilm and enhances the process of bacterial detachment, leading to a loss of bacterial biomass from the substratum.
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Affiliation(s)
- Morten Hentzer
- Department of Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Kathrin Riedel
- Lehrstuhl für Mikrobiologie, Technische Universität München, D-85350 Freising, Germany2
| | - Thomas B Rasmussen
- Department of Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Arne Heydorn
- Department of Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Jens Bo Andersen
- Department of Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Matthew R Parsek
- Department of Civil Engineering, Technological Institute, North Western University, Evanston, IL 60208-3109, USA3
| | - Scott A Rice
- School of Microbiology and Immunology, University of New South Wales (UNSW), Australia 20524
| | - Leo Eberl
- Lehrstuhl für Mikrobiologie, Technische Universität München, D-85350 Freising, Germany2
| | - Søren Molin
- Department of Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Niels Høiby
- Department of Clinical Microbiology, University Hospital (Rigshospitalet), DK-2100 Copenhagen, Denmark5
| | - Staffan Kjelleberg
- School of Microbiology and Immunology, University of New South Wales (UNSW), Australia 20524
| | - Michael Givskov
- Department of Molecular Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark1
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Riedel K, Hentzer M, Geisenberger O, Huber B, Steidle A, Wu H, Høiby N, Givskov M, Molin S, Eberl L. N-acylhomoserine-lactone-mediated communication between Pseudomonas aeruginosa and Burkholderia cepacia in mixed biofilms. Microbiology (Reading) 2001; 147:3249-62. [PMID: 11739757 DOI: 10.1099/00221287-147-12-3249] [Citation(s) in RCA: 278] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pseudomonas aeruginosa and Burkholderia cepacia are capable of forming mixed biofilms in the lungs of cystic fibrosis patients. Both bacteria employ quorum-sensing systems, which rely on N-acylhomoserine lactone (AHL) signal molecules, to co-ordinate expression of virulence factors with the formation of biofilms. As both bacteria utilize the same class of signal molecules the authors investigated whether communication between the species occurs. To address this issue, novel Gfp-based biosensors for non-destructive, in situ detection of AHLs were constructed and characterized. These sensors were used to visualize AHL-mediated communication in mixed biofilms, which were cultivated either in artificial flow chambers or in alginate beads in mouse lung tissue. In both model systems B. cepacia was capable of perceiving the AHL signals produced by P. aeruginosa, while the latter strain did not respond to the molecules produced by B. cepacia. Measurements of extracellular proteolytic activities of defined quorum-sensing mutants grown in media complemented with AHL extracts prepared from culture supernatants of various wild-type and mutant strains supported the view of unidirectional signalling between the two strains.
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Affiliation(s)
- K Riedel
- Department of Microbiology, TUM, Am Hochanger 4, D-85350 Freising, Germany
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Hentzer M, Teitzel GM, Balzer GJ, Heydorn A, Molin S, Givskov M, Parsek MR. Alginate overproduction affects Pseudomonas aeruginosa biofilm structure and function. J Bacteriol 2001; 183:5395-401. [PMID: 11514525 PMCID: PMC95424 DOI: 10.1128/jb.183.18.5395-5401.2001] [Citation(s) in RCA: 451] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2001] [Accepted: 06/15/2001] [Indexed: 11/20/2022] Open
Abstract
During the course of chronic cystic fibrosis (CF) infections, Pseudomonas aeruginosa undergoes a conversion to a mucoid phenotype, which is characterized by overproduction of the exopolysaccharide alginate. Chronic P. aeruginosa infections involve surface-attached, highly antibiotic-resistant communities of microorganisms organized in biofilms. Although biofilm formation and the conversion to mucoidy are both important aspects of CF pathogenesis, the relationship between them is at the present unclear. In this study, we report that the overproduction of alginate affects biofilm development on an abiotic surface. Biofilms formed by an alginate-overproducing strain exhibit a highly structured architecture and are significantly more resistant to the antibiotic tobramycin than a biofilm formed by an isogenic nonmucoid strain. These results suggest that an important consequence of the conversion to mucoidy is an altered biofilm architecture that shows increasing resistance to antimicrobial treatments.
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Affiliation(s)
- M Hentzer
- Department of Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark
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41
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Huber B, Riedel K, Hentzer M, Heydorn A, Gotschlich A, Givskov M, Molin S, Eberl L. The cep quorum-sensing system of Burkholderia cepacia H111 controls biofilm formation and swarming motility. Microbiology (Reading) 2001; 147:2517-2528. [PMID: 11535791 DOI: 10.1099/00221287-147-9-2517] [Citation(s) in RCA: 323] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia cepacia and Pseudomonas aeruginosa often co-exist as mixed biofilms in the lungs of patients suffering from cystic fibrosis (CF). Here, the isolation of random mini-Tn5 insertion mutants of B. cepacia H111 defective in biofilm formation on an abiotic surface is reported. It is demonstrated that one of these mutants no longer produces N-acylhomoserine lactones (AHLs) due to an inactivation of the cepR gene. cepR and the cepI AHL synthase gene together constitute the cep quorum-sensing system of B. cepacia. By using a gene replacement method, two defined mutants, H111-I and H111-R, were constructed in which cepI and cepR, respectively, had been inactivated. These mutants were used to demonstrate that biofilm formation by B. cepacia H111 requires a functional cep quorum-sensing system. A detailed quantitative analysis of the biofilm structures formed by wild-type and mutant strains suggested that the quorum-sensing system is not involved in the regulation of initial cell attachment, but rather controls the maturation of the biofilm. Furthermore, it is shown that B. cepacia is capable of swarming motility, a form of surface translocation utilized by various bacteria to rapidly colonize appropriate substrata. Evidence is provided that swarming motility of B. cepacia is quorum-sensing-regulated, possibly through the control of biosurfactant production. Complementation of the cepR mutant H111-R with different biosurfactants restored swarming motility while biofilm formation was not significantly increased. This result suggests that swarming motility per se is not essential for biofilm formation on abiotic surfaces.
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Affiliation(s)
- Birgit Huber
- Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, 85350 Freising, Germany1
| | - Kathrin Riedel
- Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, 85350 Freising, Germany1
| | - Morten Hentzer
- Department of Microbiology, DTU, Building 301, 2800 Lyngby, Denmark2
| | - Arne Heydorn
- Department of Microbiology, DTU, Building 301, 2800 Lyngby, Denmark2
| | - Astrid Gotschlich
- Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, 85350 Freising, Germany1
| | - Michael Givskov
- Department of Microbiology, DTU, Building 301, 2800 Lyngby, Denmark2
| | - Søren Molin
- Department of Microbiology, DTU, Building 301, 2800 Lyngby, Denmark2
| | - Leo Eberl
- Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, 85350 Freising, Germany1
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42
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Charlton T, Givskov M, deNys R, Andersen JB, Hentzer M, Rice S, Kjelleberg S. Genetic and chemical tools for investigating signaling processes in biofilms. Methods Enzymol 2001; 336:108-28. [PMID: 11398393 DOI: 10.1016/s0076-6879(01)36584-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- T Charlton
- School of Microbiology and Immunology, Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney 2052, Australia
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Andersen JB, Heydorn A, Hentzer M, Eberl L, Geisenberger O, Christensen BB, Molin S, Givskov M. gfp-based N-acyl homoserine-lactone sensor systems for detection of bacterial communication. Appl Environ Microbiol 2001; 67:575-85. [PMID: 11157219 PMCID: PMC92623 DOI: 10.1128/aem.67.2.575-585.2001] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to perform single-cell analysis and online studies of N-acyl homoserine lactone (AHL)-mediated communication among bacteria, components of the Vibrio fischeri quorum sensor encoded by luxR-P(luxI) have been fused to modified versions of gfpmut3* genes encoding unstable green fluorescent proteins. Bacterial strains harboring this green fluorescent sensor detected a broad spectrum of AHL molecules and were capable of sensing the presence of 5 nM N-3-oxohexanoyl-L-homoserine lactone in the surroundings. In combination with epifluorescent microscopy, the sensitivity of the sensor enabled AHL detection at the single-cell level and allowed for real-time measurements of fluctuations in AHL concentrations. This green fluorescent AHL sensor provides a state-of-the-art tool for studies of communication between the individuals present in mixed bacterial communities.
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Affiliation(s)
- J B Andersen
- Department of Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark
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44
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Heydorn A, Nielsen AT, Hentzer M, Sternberg C, Givskov M, Ersbøll BK, Molin S. Quantification of biofilm structures by the novel computer program COMSTAT. Microbiology (Reading) 2000; 146 ( Pt 10):2395-2407. [PMID: 11021916 DOI: 10.1099/00221287-146-10-2395] [Citation(s) in RCA: 1558] [Impact Index Per Article: 64.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The structural organization of four microbial communities was analysed by a novel computer program, COMSTAT, which comprises ten features for quantifying three-dimensional biofilm image stacks. Monospecies biofilms of each of the four bacteria, Pseudomonas: putida, P. aureofaciens, P. fluorescens and P. aeruginosa, tagged with the green fluorescent protein (GFP) were grown in flow chambers with a defined minimal medium as substrate. Analysis by the COMSTAT program of four variables describing biofilm structure - mean thickness, roughness, substratum coverage and surface to volume ratio - showed that the four Pseudomonas: strains represent different modes of biofilm growth. P. putida had a unique developmental pattern starting with single cells on the substratum growing into micro-colonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a stronger tendency to form micro-colonies. Finally, the biofilm structures of P. fluorescens had a phenotype intermediate between those of P. putida and P. aureofaciens. Analysis of biofilms of P. aureofaciens growing on 0.03 mM, 0.1 mM or 0.5 mM citrate minimal media showed that mean biofilm thickness increased with increasing citrate concentration. Moreover, biofilm roughness increased with lower citrate concentrations, whereas surface to volume ratio increased with higher citrate concentrations.
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Affiliation(s)
- Arne Heydorn
- Molecular Microbial Ecology Group, Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Alex Toftgaard Nielsen
- Molecular Microbial Ecology Group, Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Morten Hentzer
- Molecular Microbial Ecology Group, Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Claus Sternberg
- Molecular Microbial Ecology Group, Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Michael Givskov
- Molecular Microbial Ecology Group, Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark1
| | - Bjarne Kjær Ersbøll
- Department of Mathematical Modelling, The Technical University of Denmark, DK-2800 Lyngby, Denmark2
| | - Søren Molin
- Molecular Microbial Ecology Group, Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark1
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Heydorn A, Ersbøll BK, Hentzer M, Parsek MR, Givskov M, Molin S. Experimental reproducibility in flow-chamber biofilms. Microbiology (Reading) 2000; 146 ( Pt 10):2409-2415. [PMID: 11021917 DOI: 10.1099/00221287-146-10-2409] [Citation(s) in RCA: 206] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The structural organization of microbial communities is influenced by many factors, e.g. nutrient composition, shear stress and temperature. This paper presents a general method for quantitative comparison of biofilm structures and assessment of experimental reproducibility between independent biofilm experiments. By using a novel computer program, COMSTAT, biofilm structures of Pseudomonas aeruginosa and an isogenic rpoS mutant were quantified. The strains were tagged with the green fluorescent protein (GFP) and grown in flow chambers with a defined minimal medium as substrate. Three independent rounds of biofilm experiments were performed and in each round, each of the two variants was grown in two separate channels. Nine image stacks were acquired in each channel 146 h after inoculation. An analysis of variance model incorporating the factors experiment round, bacterial strain, channel number and image stack number was used to analyse the data calculated by COMSTAT. Experimental reproducibility was verified by estimating the magnitude of the variance of the effects round (sigma(2)R) and the interaction between bacterial strain and round (sigma(2)BR). Mean thickness of the wild-type and rpoS mutant biofilms was estimated at 6.31 microm (SE 0.81 microm) and 16.85 microm (SE 0.87 microm), respectively.
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Affiliation(s)
- Arne Heydorn
- Molecular Microbial Ecology Group, Department of Microbiology, The Technical University of Denmark block 301,DK-2800 Lyngby, Denmark1
| | - Bjarne Kjær Ersbøll
- Department of Mathematical Modelling, The Technical University of Denmark, DK-2800 Lyngby, Denmark2
| | - Morten Hentzer
- Molecular Microbial Ecology Group, Department of Microbiology, The Technical University of Denmark block 301,DK-2800 Lyngby, Denmark1
| | - Matthew R Parsek
- Environmental Engineering Group, Department of Civil Engineering, NorthWestern University, Evanston, Illinois, USA3
| | - Michael Givskov
- Molecular Microbial Ecology Group, Department of Microbiology, The Technical University of Denmark block 301,DK-2800 Lyngby, Denmark1
| | - Søren Molin
- Molecular Microbial Ecology Group, Department of Microbiology, The Technical University of Denmark block 301,DK-2800 Lyngby, Denmark1
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46
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Charlton TS, de Nys R, Netting A, Kumar N, Hentzer M, Givskov M, Kjelleberg S. A novel and sensitive method for the quantification of N-3-oxoacyl homoserine lactones using gas chromatography-mass spectrometry: application to a model bacterial biofilm. Environ Microbiol 2000; 2:530-41. [PMID: 11233161 DOI: 10.1046/j.1462-2920.2000.00136.x] [Citation(s) in RCA: 232] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A method is reported for the quantification of 3-oxoacyl homoserine lactones (3-oxo AHLs), a major class of quorum-sensing signals found in Gram-negative bacteria. It is based on the conversion of 3-oxo AHLs to their pentafluorobenzyloxime derivatives followed by gas chromatography-mass spectrometry (electron capture-negative ion). The method used [13C16]-N-3-oxo-dodecanoyl homoserine lactone ([13C16]-OdDHL) as the internal standard, and its validity was tested by spiking the supernatant and cell fractions with three levels of 3-oxo AHLs, i.e. 1, 10 and 100 ng per sample. These showed the method to be both sensitive (S/N ratio >10:1 for 1 ng) and accurate. The assay was applied to the biofilm and effluent of a green fluorescent protein (GFP)-expressing strain of Pseudomonas aeruginosa (6294) culture grown in flow cells. Biofilm volume was determined for three replicate flow cells by confocal scanning laser microscopy. OdDHL was detected in the biofilm at 632 +/- 381 microM and the effluent at 14 +/- 3 nM. The biofilm concentration is the highest level so far reported for an AHL in a wild-type bacterial system. The next most abundant 3-oxo AHL in the biofilm and effluent was N-3-oxo-tetradecanoyl homoserine lactone (OtDHL) at 40 +/- 15 microM and 1.5 +/- 0.7 nM respectively. OtDHL is unreported for P. aeruginosa and has an activity equivalent to OdDHL in a lasR bioassay. Two other 3-oxo AHLs were detected at lower concentrations: N3-oxo-decanoyl homoserine lactone (ODHL) in the biofilm (3 +/- 2 microM) and effluent (1 +/- 0.1 nM); and N-3-oxo-octanoyl homoserine lactone (OOHL) in the effluent (0.1 +/- 0.1 nM).
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Affiliation(s)
- T S Charlton
- School of Microbiology and Immunology, University of New South Wales, Australia
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Abstract
Antisense expression of a portion of the gene encoding the major carbon catabolite repressor CREA in Aspergillus nidulans resulted in a substantial increase in the levels of glucose-repressible enzymes, both endogenous and heterologous, in the presence of glucose. The derepression effect was approximately one-half of that achieved in a null creA mutant. Unlike results for that mutant, however, growth parameters and colony morphology in the antisense transformants were not affected.
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Affiliation(s)
- L F Bautista
- Center for Process Biotechnology, Department of Biotechnology, Technical University of Denmark, 2800 Lyngby, Denmark
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48
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Wu H, Song Z, Hentzer M, Andersen JB, Heydorn A, Mathee K, Moser C, Eberl L, Molin S, Høiby N, Givskov M. Detection of N-acylhomoserine lactones in lung tissues of mice infected with Pseudomonas aeruginosa. Microbiology (Reading) 2000; 146 ( Pt 10):2481-2493. [PMID: 11021924 DOI: 10.1099/00221287-146-10-2481] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The pathogenesis of Pseudomonas aeruginosa is associated with expression of virulence factors, many of which are controlled by two N:-acylhomoserine lactone (AHL)-based quorum-sensing systems. Escherichia coli strains equipped with a luxR-based monitor system expressing green fluorescent protein (GFP) in the presence of exogenous AHL molecules were used to detect the production of AHLs from P. aeruginosa in vivo. Mice were challenged intratracheally with alginate beads containing P. aeruginosa and E. coli and killed on different days after the challenge. By means of confocal scanning laser microscopy, GFP-expressing E. coli bacteria could be detected in the lung tissues, indicating production and excretion of AHL molecules in vivo by the infecting P. aeruginosa. AHL signals were detected mainly in lung tissues exhibiting severe pathological changes. These findings support the view that expression of AHL molecules by P. aeruginosa during infection coincides with its pathogenesis.
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Affiliation(s)
- Hong Wu
- Department of Clinical Microbiology, University Hospital (Rigshospitalet), Copenhagen Ø, DK-2100, Denmark1
| | - Zhijun Song
- Department of Clinical Microbiology, University Hospital (Rigshospitalet), Copenhagen Ø, DK-2100, Denmark1
| | - Morten Hentzer
- Department of Microbiology, the Technical University of Denmark, Lyngby,DK-2800, Denmark2
| | - Jens Bo Andersen
- Department of Microbiology, the Technical University of Denmark, Lyngby,DK-2800, Denmark2
| | - Arne Heydorn
- Department of Microbiology, the Technical University of Denmark, Lyngby,DK-2800, Denmark2
| | - Kalai Mathee
- Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199, USA3
| | - Claus Moser
- Department of Clinical Microbiology, University Hospital (Rigshospitalet), Copenhagen Ø, DK-2100, Denmark1
| | - Leo Eberl
- Lehrstuhl fur Mikrobiologie, Technische Universitat Munchen, Freising D-85350, Germany4
| | - Søren Molin
- Department of Microbiology, the Technical University of Denmark, Lyngby,DK-2800, Denmark2
| | - Niels Høiby
- Department of Clinical Microbiology, University Hospital (Rigshospitalet), Copenhagen Ø, DK-2100, Denmark1
| | - Michael Givskov
- Department of Microbiology, the Technical University of Denmark, Lyngby,DK-2800, Denmark2
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