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da Cruz Nizer WS, Adams ME, Allison KN, Montgomery MC, Mosher H, Cassol E, Overhage J. Oxidative stress responses in biofilms. Biofilm 2024; 7:100203. [PMID: 38827632 PMCID: PMC11139773 DOI: 10.1016/j.bioflm.2024.100203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/22/2024] [Accepted: 05/22/2024] [Indexed: 06/04/2024] Open
Abstract
Oxidizing agents are low-molecular-weight molecules that oxidize other substances by accepting electrons from them. They include reactive oxygen species (ROS), such as superoxide anions (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (HO-), and reactive chlorine species (RCS) including sodium hypochlorite (NaOCl) and its active ingredient hypochlorous acid (HOCl), and chloramines. Bacteria encounter oxidizing agents in many different environments and from diverse sources. Among them, they can be produced endogenously by aerobic respiration or exogenously by the use of disinfectants and cleaning agents, as well as by the mammalian immune system. Furthermore, human activities like industrial effluent pollution, agricultural runoff, and environmental activities like volcanic eruptions and photosynthesis are also sources of oxidants. Despite their antimicrobial effects, bacteria have developed many mechanisms to resist the damage caused by these toxic molecules. Previous research has demonstrated that growing as a biofilm particularly enhances bacterial survival against oxidizing agents. This review aims to summarize the current knowledge on the resistance mechanisms employed by bacterial biofilms against ROS and RCS, focussing on the most important mechanisms, including the formation of biofilms in response to oxidative stressors, the biofilm matrix as a protective barrier, the importance of detoxifying enzymes, and increased protection within multi-species biofilm communities. Understanding the complexity of bacterial responses against oxidative stress will provide valuable insights for potential therapeutic interventions and biofilm control strategies in diverse bacterial species.
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Affiliation(s)
| | - Madison Elisabeth Adams
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | - Kira Noelle Allison
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | | | - Hailey Mosher
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | - Edana Cassol
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | - Joerg Overhage
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
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2
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Mirzaei R, Campoccia D, Ravaioli S, Arciola CR. Emerging Issues and Initial Insights into Bacterial Biofilms: From Orthopedic Infection to Metabolomics. Antibiotics (Basel) 2024; 13:184. [PMID: 38391570 PMCID: PMC10885942 DOI: 10.3390/antibiotics13020184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/29/2024] [Accepted: 02/07/2024] [Indexed: 02/24/2024] Open
Abstract
Bacterial biofilms, enigmatic communities of microorganisms enclosed in an extracellular matrix, still represent an open challenge in many clinical contexts, including orthopedics, where biofilm-associated bone and joint infections remain the main cause of implant failure. This study explores the scenario of biofilm infections, with a focus on those related to orthopedic implants, highlighting recently emerged substantial aspects of the pathogenesis and their potential repercussions on the clinic, as well as the progress and gaps that still exist in the diagnostics and management of these infections. The classic mechanisms through which biofilms form and the more recently proposed new ones are depicted. The ways in which bacteria hide, become impenetrable to antibiotics, and evade the immune defenses, creating reservoirs of bacteria difficult to detect and reach, are delineated, such as bacterial dormancy within biofilms, entry into host cells, and penetration into bone canaliculi. New findings on biofilm formation with host components are presented. The article also delves into the emerging and critical concept of immunometabolism, a key function of immune cells that biofilm interferes with. The growing potential of biofilm metabolomics in the diagnosis and therapy of biofilm infections is highlighted, referring to the latest research.
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Affiliation(s)
- Rasoul Mirzaei
- Venom and Biotherapeutics Molecules Laboratory, Medical Biotechnology Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran 1316943551, Iran
| | - Davide Campoccia
- Laboratorio di Patologia delle Infezioni Associate all'Impianto, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
| | - Stefano Ravaioli
- Laboratorio di Patologia delle Infezioni Associate all'Impianto, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
| | - Carla Renata Arciola
- Laboratory of Immunorheumatology and Tissue Regeneration, Laboratory of Pathology of Implant Infections, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Via San Giacomo 14, 40126 Bologna, Italy
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3
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Campoccia D, Ravaioli S, Mirzaei R, Bua G, Daglia M, Arciola CR. Interactions of Neutrophils with the Polymeric Molecular Components of the Biofilm Matrix in the Context of Implant-Associated Bone and Joint Infections. Int J Mol Sci 2023; 24:17042. [PMID: 38069365 PMCID: PMC10707472 DOI: 10.3390/ijms242317042] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/29/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
In the presence of orthopedic implants, opportunistic pathogens can easily colonize the biomaterial surfaces, forming protective biofilms. Life in biofilm is a central pathogenetic mechanism enabling bacteria to elude the host immune response and survive conventional medical treatments. The formation of mature biofilms is universally recognized as the main cause of septic prosthetic failures. Neutrophils are the first leukocytes to be recruited at the site of infection. They are highly efficient in detecting and killing planktonic bacteria. However, the interactions of these fundamental effector cells of the immune system with the biofilm matrix, which is the true interface of a biofilm with the host cells, have only recently started to be unveiled and are still to be fully understood. Biofilm matrix macromolecules consist of exopolysaccharides, proteins, lipids, teichoic acids, and the most recently described extracellular DNA. The latter can also be stolen from neutrophil extracellular traps (NETs) by bacteria, who use it to strengthen their biofilms. This paper aims to review the specific interactions that neutrophils develop when they physically encounter the matrix of a biofilm and come to interact with its polymeric molecular components.
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Affiliation(s)
- Davide Campoccia
- Laboratorio di Patologia Delle Infezioni Associate all’Impianto, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy; (D.C.); (S.R.); (G.B.)
| | - Stefano Ravaioli
- Laboratorio di Patologia Delle Infezioni Associate all’Impianto, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy; (D.C.); (S.R.); (G.B.)
| | - Rasoul Mirzaei
- Venom and Biotherapeutics Molecules Laboratory, Medical Biotechnology Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran 1316943551, Iran;
| | - Gloria Bua
- Laboratorio di Patologia Delle Infezioni Associate all’Impianto, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy; (D.C.); (S.R.); (G.B.)
| | - Maria Daglia
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Naples, Italy;
- International Research Center for Food Nutrition and Safety, Jiangsu University, Zhenjiang 212013, China
| | - Carla Renata Arciola
- Laboratory of Immunorheumatology and Tissue Regeneration, Laboratory of Pathology of Implant Infections, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Via San Giacomo 14, 40126 Bologna, Italy
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4
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Low KE, Gheorghita AA, Tammam SD, Whitfield GB, Li YE, Riley LM, Weadge JT, Caldwell SJ, Chong PA, Walvoort MTC, Kitova EN, Klassen JS, Codée JDC, Howell PL. Pseudomonas aeruginosa AlgF is a protein-protein interaction mediator required for acetylation of the alginate exopolysaccharide. J Biol Chem 2023; 299:105314. [PMID: 37797696 PMCID: PMC10641220 DOI: 10.1016/j.jbc.2023.105314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023] Open
Abstract
Enzymatic modifications of bacterial exopolysaccharides enhance immune evasion and persistence during infection. In the Gram-negative opportunistic pathogen Pseudomonas aeruginosa, acetylation of alginate reduces opsonic killing by phagocytes and improves reactive oxygen species scavenging. Although it is well known that alginate acetylation in P. aeruginosa requires AlgI, AlgJ, AlgF, and AlgX, how these proteins coordinate polymer modification at a molecular level remains unclear. Here, we describe the structural characterization of AlgF and its protein interaction network. We characterize direct interactions between AlgF and both AlgJ and AlgX in vitro and demonstrate an association between AlgF and AlgX, as well as AlgJ and AlgI, in P. aeruginosa. We determine that AlgF does not exhibit acetylesterase activity and is unable to bind to polymannuronate in vitro. Therefore, we propose that AlgF functions to mediate protein-protein interactions between alginate acetylation enzymes, forming the periplasmic AlgJFXK (AlgJ-AlgF-AlgX-AlgK) acetylation and export complex required for robust biofilm formation.
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Affiliation(s)
- Kristin E Low
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Andreea A Gheorghita
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Stephanie D Tammam
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Gregory B Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yancheng E Li
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Laura M Riley
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Joel T Weadge
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Shane J Caldwell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - P Andrew Chong
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | | | - Elena N Kitova
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - John S Klassen
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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5
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Balducci E, Papi F, Capialbi DE, Del Bino L. Polysaccharides' Structures and Functions in Biofilm Architecture of Antimicrobial-Resistant (AMR) Pathogens. Int J Mol Sci 2023; 24:ijms24044030. [PMID: 36835442 PMCID: PMC9965654 DOI: 10.3390/ijms24044030] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
Bacteria and fungi have developed resistance to the existing therapies such as antibiotics and antifungal drugs, and multiple mechanisms are mediating this resistance. Among these, the formation of an extracellular matrix embedding different bacterial cells, called biofilm, is an effective strategy through which bacterial and fungal cells are establishing a relationship in a unique environment. The biofilm provides them the possibility to transfer genes conferring resistance, to prevent them from desiccation and to impede the penetration of antibiotics or antifungal drugs. Biofilms are formed of several constituents including extracellular DNA, proteins and polysaccharides. Depending on the bacteria, different polysaccharides form the biofilm matrix in different microorganisms, some of them involved in the first stage of cells' attachment to surfaces and to each other, and some responsible for giving the biofilm structure resistance and stability. In this review, we describe the structure and the role of different polysaccharides in bacterial and fungal biofilms, we revise the analytical methods to characterize them quantitatively and qualitatively and finally we provide an overview of potential new antimicrobial therapies able to inhibit biofilm formation by targeting exopolysaccharides.
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Affiliation(s)
| | | | - Daniela Eloisa Capialbi
- GSK, 53100 Siena, Italy
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100 Siena, Italy
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UVA as environmental signal for alginate production in Pseudomonas aeruginosa: role of this polysaccharide in the protection of planktonic cells and biofilms against lethal UVA doses. Photochem Photobiol Sci 2022; 21:1459-1472. [PMID: 35551642 DOI: 10.1007/s43630-022-00236-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
Abstract
Pseudomonas aeruginosa is an extremely versatile microorganism that survives in a wide variety of niches. It is capable to respond rapidly to changes in the environment by producing secondary metabolites and virulence factors, including alginate. Alginate is an extracellular polysaccharide that protects the bacteria from antibiotics and oxidative agents, and enhances cell adhesion to solid surfaces in the process of biofilm formation. In the present study, we analyzed the role of alginate in the response of P. aeruginosa to lethal doses of ultraviolet-A (UVA) radiation, the major fraction of solar UV radiation reaching the Earth's surface. We also studied the role of alginate in the context of the adaptive responses generated when P. aeruginosa is exposed to sublethal doses of UVA radiation. The survival studies demonstrated that alginate has a key role in the resistance of P. aeruginosa to the oxidative stress generated by lethal UVA doses, both in planktonic cells and in static biofilms. In addition, the presence of alginate proved to be essential in the occurrence of adaptive responses such as induction of biofilm formation and cross-protection against hydrogen peroxide and sodium hypochlorite, both generated by exposure to low UVA doses. Finally, we demonstrated that the increase of biofilm formation is accompanied by an increase in alginate concentration in the biofilm matrix, possibly through the ppGpp-dependent induction of genes related to alginate regulation (algR and algU) and biosynthesis (algD operon). Given the importance of alginate in biofilm formation and its protective roles, better understanding of the mechanisms associated to its functions and synthesis is relevant, given the normal exposure of P. aeruginosa to UVA radiation and other types of oxidative stresses.
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Azimi S, Safari Zanjani L. Immunization against Pseudomonas aeruginosa using Alg-PLGA nano-vaccine. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2021; 24:476-482. [PMID: 34094029 PMCID: PMC8143718 DOI: 10.22038/ijbms.2021.52217.11813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/02/2021] [Indexed: 12/27/2022]
Abstract
OBJECTIVES Pseudomonas aeruginosa is the bacterium that causes of pulmonary infection among chronically hospitalized patients. Alginate is a common surface antigen of P. aeruginosa with a constant structure that which makes it an appropriate target for vaccines. In this study, P. aeruginosa alginate was conjugated with to PLGA nanoparticles, and its immunogenicity was characterized as a vaccine. MATERIALS AND METHODS Alginate was isolated from a mucoid strain of P. aeruginosa and conjugated with to PLGA with˝ N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride ˝= ˝EDAC˝ and N-Hydroxysuccinimide (NHS). Chemical characterization of prepared nano-vaccine was performed using FTIR Spectroscopy, Zetasizer, and Atomic Force Microscopy (AFM). The immunogenicity of this nano-vaccine was evaluated through intramuscular injection into BALB/c mice. Four groups of mice were subjected to the injection of alginate-PLGA, and two weeks after the last administration step, opsonophagocytosis assay, IgG detection, challenge, and cytokine determination via ELISA were carried out. RESULTS Alginate-PLGA conjugation was corroborated by FTIR, Zetasizer, and AFM. The ELISA consequence showed that alginate was prospering in the instigation of the humoral immunity.The immunogenicity enhanced against the alginate-PLGA. Remarkably diminished bacterial titer in the spleen of the immunized mice posterior to challenge with PAO1 strain in comparison with the alginate alone and control groups. CONCLUSION The bacterial burden in the spleen significantly decreased after the challenge (P<0.05). The opsonic activity was significantly increased in the alginate- PLGA group (P<0.05).
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Affiliation(s)
| | - Leila Safari Zanjani
- Department of Cellular and Molecular Biology, Zanjan Branch, Payame Noor of Zanjan, Zanjan, Iran
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Kwong K, Benedetti A, Yau Y, Waters V, Nguyen D. Failed eradication therapy of new onset Pseudomonas aeruginosa infections in cystic fibrosis children is associated with bacterial resistance to neutrophil functions. J Infect Dis 2021; 225:1886-1895. [PMID: 33606875 PMCID: PMC9159338 DOI: 10.1093/infdis/jiab102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/12/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Antibiotics, such as inhaled tobramycin are used to eradicate new onset Pseudomonas aeruginosa (PA) infections in cystic fibrosis (CF) patients but frequently fail due to reasons poorly understood. We hypothesized that PA isolates' resistance to neutrophil antibacterial functions was associated with failed eradication in patients harboring those strains. METHODS We analyzed all PA isolates from a cohort of 39 CF children with new onset PA infections undergoing tobramycin eradication therapy, where N=30 patients had eradicated and N=9 patients had persistent infection. We characterized several bacterial phenotypes and measured the isolates' susceptibility to neutrophil antibacterial functions using in vitro assays of phagocytosis and intracellular bacterial killing. RESULTS PA isolates from persistent infections were more resistant to neutrophil functions, with lower phagocytosis and intracellular bacterial killing compared to those from eradicated infections. In multivariable analyses, in vitro neutrophil responses were positively associated with twitching motility, and negatively with mucoidy. In vitro neutrophil phagocytosis was a predictor of persistent infection following tobramycin even after adjustment for clinical risk factors. CONCLUSIONS PA isolates from new onset CF infection show strain-specific susceptibility to neutrophil antibacterial functions, and infection with PA isolates resistant to neutrophil phagocytosis is an independent risk factor for failed tobramycin eradication.
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Affiliation(s)
- K Kwong
- Department of Microbiology and Immunology, McGill University, Montreal, CA.,Meakins Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, CA
| | - A Benedetti
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, CA.,Centre for Health Outcome Research, Research Institute of the McGill University Health Centre, Montreal, CA
| | - Y Yau
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, CA.,Division of Microbiology, Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, CA
| | - V Waters
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, CA.,Division of Infectious Diseases, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, CA
| | - D Nguyen
- Department of Microbiology and Immunology, McGill University, Montreal, CA.,Meakins Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, CA.,Department of Medicine, McGill University, Montreal, CA
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The Extracellular Polysaccharide Matrix of Pseudomonas aeruginosa Biofilms Is a Determinant of Polymorphonuclear Leukocyte Responses. Infect Immun 2020; 89:IAI.00631-20. [PMID: 33077623 DOI: 10.1128/iai.00631-20] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 10/09/2020] [Indexed: 01/04/2023] Open
Abstract
Bacterial biofilms may cause chronic infections due to their ability to evade clearance by the immune system and antibiotics. The persistent biofilms induce a hyperinflammatory state that damages the surrounding host tissue. Knowledge about the components of biofilms that are responsible for provoking the harmful but inefficient immune response is limited. Flagella are known to stimulate the response of polymorphonuclear leukocytes (PMNs) to planktonic solitary bacteria. However, we provide evidence that flagella are not a prerequisite for the response of PMNs to Pseudomonas aeruginosa biofilms. Instead, we found that extracellular matrix polysaccharides in P. aeruginosa biofilms play a role in the response of PMNs toward biofilms. Using a set of P. aeruginosa mutants with the ability to produce a subset of matrix exopolysaccharides, we found that P. aeruginosa biofilms with distinct exopolysaccharide matrix components elicit distinct PMN responses. In particular, the PMNs respond aggressively toward a biofilm matrix consisting of both Psl and alginate exopolysaccharides. These findings are relevant for therapeutic strategies aimed at dampening the collateral damage associated with biofilm-based infections.
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10
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Jackson L, Waters V. Factors influencing the acquisition and eradication of early Pseudomonas aeruginosa infection in cystic fibrosis. J Cyst Fibros 2020; 20:8-16. [PMID: 33172756 DOI: 10.1016/j.jcf.2020.10.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/02/2020] [Accepted: 10/27/2020] [Indexed: 12/21/2022]
Abstract
In recent years considerable improvements have been made in increasing the life expectancy of patients with cystic fibrosis. New highly effective modulator therapies targeting the underlying defect in the cystic fibrosis transmembrane conductance regulator protein are expected to enhance lifespan even further. However, chronic Pseudomonas aeruginosa pulmonary infections continue to threaten CF patient lung health and mortality rates. Early and aggressive antibiotic eradication therapies targeting P. aeruginosa are standard practice, but these eradication therapies fail in 10-40% of patients. The reasons for P. aeruginosa eradication failure remain unclear. Thus, this review summarizes the evidence to date for pseudomonal acquisition and eradication failure in the cystic fibrosis lung. A complex combination of host and bacterial factors are responsible for initial establishment of P. aeruginosa pulmonary infections. Moreover, host and pseudomonal factors, polymicrobial interactions, and antimicrobial limitations in relation to P. aeruginosa eradication therapy failure are summarized.
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Affiliation(s)
- Lindsay Jackson
- Translational Medicine, Hospital for Sick Children, Toronto, Canada.
| | - Valerie Waters
- Translational Medicine, Hospital for Sick Children, Toronto, Canada; Infectious Diseases, Department of Pediatrics, Hospital for Sick Children, Toronto, Canada
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Avasarala S, Torres C, Ali AMS, Thomson BM, Spilde MN, Peterson EJ, Artyushkova K, Dobrica E, Lezama-Pacheco JS, Cerrato JM. Effect of Bicarbonate and Oxidizing Conditions on U(IV) and U(VI) Reactivity in Mineralized Deposits of New Mexico. CHEMICAL GEOLOGY 2019; 524:345-355. [PMID: 31406388 PMCID: PMC6690612 DOI: 10.1016/j.chemgeo.2019.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We investigated the effect of bicarbonate and oxidizing agents on uranium (U) reactivity and subsequent dissolution of U(IV) and U(VI) mineral phases in the mineralized deposits from Jackpile mine, Laguna Pueblo, New Mexico, by integrating laboratory experiments with spectroscopy, microscopy and diffraction techniques. Uranium concentration in solid samples from mineralized deposit obtained for this study exceeded 7000 mg kg-1, as determined by X-ray fluorescence (XRF). Results from X-ray photoelectron spectroscopy (XPS) suggest the coexistence of U(VI) and U(IV) at a ratio of 19:1 at the near surface region of unreacted solid samples. Analyses made using X-ray diffraction (XRD) and electron microprobe detected the presence of coffinite (USiO4) and uranium-phosphorous-potassium (U-P-K) mineral phases. Imaging, mapping and spectroscopy results from scanning transmission electron microscopy (STEM) indicate that the U-P-K phases were encapsulated by carbon. Despite exposing the solid samples to strong oxidizing conditions, the highest aqueous U concentrations were measured from samples reacted with 100% air saturated 10 mM NaHCO3 solution, at pH 7.5. Analyses using X-ray absorption spectroscopy (XAS) indicate that all the U(IV) in these solid samples were oxidized to U(VI) after reaction with dissolved oxygen and hypochlorite (OCl-) in the presence of bicarbonate (HCO3 -). The reaction between these organic rich deposits, and 100% air saturated bicarbonate solution (containing dissolved oxygen), can result in considerable mobilization of U in water, which has relevance to the U concentrations observed at the Rio Paguate across the Jackpile mine. Results from this investigation provide insights on the reactivity of carbon encapsulated U-phases under mild and strong oxidizing conditions that have important implication in U recovery, remediation and risk exposure assessment of sites.
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Affiliation(s)
- Sumant Avasarala
- Department of Civil, Construction, & Environmental Engineering, MSC01 1070, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Chris Torres
- Department of Chemical and Biological Engineering, MSC01 1120, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Abdul-Mehdi S. Ali
- Department of Earth and Planetary Sciences, MSC03 2040, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Bruce M. Thomson
- Department of Civil, Construction, & Environmental Engineering, MSC01 1070, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Michael N. Spilde
- Department of Earth and Planetary Sciences, MSC03 2040, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Eric J. Peterson
- Department of Chemical and Biological Engineering, MSC01 1120, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Kateryna Artyushkova
- Department of Chemical and Biological Engineering, MSC01 1120, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Elena Dobrica
- Department of Earth and Planetary Sciences, MSC03 2040, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | | | - José M. Cerrato
- Department of Chemical and Biological Engineering, MSC01 1120, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Malhotra S, Hayes D, Wozniak DJ. Cystic Fibrosis and Pseudomonas aeruginosa: the Host-Microbe Interface. Clin Microbiol Rev 2019; 32:e00138-18. [PMID: 31142499 PMCID: PMC6589863 DOI: 10.1128/cmr.00138-18] [Citation(s) in RCA: 244] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In human pathophysiology, the clash between microbial infection and host immunity contributes to multiple diseases. Cystic fibrosis (CF) is a classical example of this phenomenon, wherein a dysfunctional, hyperinflammatory immune response combined with chronic pulmonary infections wreak havoc upon the airway, leading to a disease course of substantial morbidity and shortened life span. Pseudomonas aeruginosa is an opportunistic pathogen that commonly infects the CF lung, promoting an accelerated decline of pulmonary function. Importantly, P. aeruginosa exhibits significant resistance to innate immune effectors and to antibiotics, in part, by expressing specific virulence factors (e.g., antioxidants and exopolysaccharides) and by acquiring adaptive mutations during chronic infection. In an effort to review our current understanding of the host-pathogen interface driving CF pulmonary disease, we discuss (i) the progression of disease within the primitive CF lung, specifically focusing on the role of host versus bacterial factors; (ii) critical, neutrophil-derived innate immune effectors that are implicated in CF pulmonary disease, including reactive oxygen species (ROS) and antimicrobial peptides (e.g., LL-37); (iii) P. aeruginosa virulence factors and adaptive mutations that enable evasion of the host response; and (iv) ongoing work examining the distribution and colocalization of host and bacterial factors within distinct anatomical niches of the CF lung.
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Affiliation(s)
- Sankalp Malhotra
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
- The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Don Hayes
- The Ohio State University College of Medicine, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
- Section of Pulmonary Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Daniel J Wozniak
- The Ohio State University College of Medicine, Columbus, Ohio, USA
- Section of Pulmonary Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
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Faure E, Kwong K, Nguyen D. Pseudomonas aeruginosa in Chronic Lung Infections: How to Adapt Within the Host? Front Immunol 2018; 9:2416. [PMID: 30405616 PMCID: PMC6204374 DOI: 10.3389/fimmu.2018.02416] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 10/01/2018] [Indexed: 01/29/2023] Open
Abstract
Bacteria that readily adapt to different natural environments, can also exploit this versatility upon infection of the host to persist. Pseudomonas aeruginosa, a ubiquitous Gram-negative bacterium, is harmless to healthy individuals, and yet a formidable opportunistic pathogen in compromised hosts. When pathogenic, P. aeruginosa causes invasive and highly lethal disease in certain compromised hosts. In others, such as individuals with the genetic disease cystic fibrosis, this pathogen causes chronic lung infections which persist for decades. During chronic lung infections, P. aeruginosa adapts to the host environment by evolving toward a state of reduced bacterial invasiveness that favors bacterial persistence without causing overwhelming host injury. Host responses to chronic P. aeruginosa infections are complex and dynamic, ranging from vigorous activation of innate immune responses that are ineffective at eradicating the infecting bacteria, to relative host tolerance and dampened activation of host immunity. This review will examine how P. aeruginosa subverts host defenses and modulates immune and inflammatory responses during chronic infection. This dynamic interplay between host and pathogen is a major determinant in the pathogenesis of chronic P. aeruginosa lung infections.
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Affiliation(s)
- Emmanuel Faure
- Department of Medicine, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Kelly Kwong
- Department of Medicine, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Dao Nguyen
- Department of Medicine, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
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Yu Z, Zhou Z, Huang G, Zheng X, Wu L, Zhao S, Meng F. Two-Dimensional FTIR Spectroscopic Characterization of Functional Groups of NaOCl-Exposed Alginate: Insights into Membrane Refouling after Online Chemical Cleaning. ACS APPLIED BIO MATERIALS 2018; 1:593-603. [DOI: 10.1021/acsabm.8b00082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Zhong Yu
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, PR China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Zhongbo Zhou
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, PR China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Guocheng Huang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, PR China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Xing Zheng
- Department of Civil and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
| | - Linjie Wu
- Department of Civil and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
| | - Shanshan Zhao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, PR China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Fangang Meng
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, PR China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
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15
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Polymorphonuclear Leukocytes or Hydrogen Peroxide Enhance Biofilm Development of Mucoid Pseudomonas aeruginosa. Mediators Inflamm 2018; 2018:8151362. [PMID: 30116152 PMCID: PMC6079396 DOI: 10.1155/2018/8151362] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/13/2018] [Accepted: 04/16/2018] [Indexed: 01/05/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogenic bacterium involved in many human infections, including pneumonia, diabetic foot ulcers, and ventilator-associated pneumonia. P. aeruginosa cells usually undergo mucoid conversion during chronic lung infection in patients with cystic fibrosis (CF) and resist destruction by polymorphonuclear leukocytes (PMNs), which release free oxygen radicals (ROS), such as H2O2. PMNs are the main leucocytes in the CF sputum of patients who are infected with P. aeruginosa, which usually forms biofilms. Here, we report that PMNs or H2O2 can promote biofilm formation by mucoid P. aeruginosa FRD1 with the use of the hanging-peg method. The mucoid strain infecting CF patients overproduces alginate. In this study, PMNs and H2O2 promoted alginate production, and biofilms treated with PMNs or H2O2 exhibited higher expression of alginate genes. Additionally, PMNs increased the activity of GDP-mannose dehydrogenase, which is the key enzyme in alginate biosynthesis. Our results demonstrate that PMNs or H2O2 can enhance mucoid P. aeruginosa biofilms.
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Malhotra S, Limoli DH, English AE, Parsek MR, Wozniak DJ. Mixed Communities of Mucoid and Nonmucoid Pseudomonas aeruginosa Exhibit Enhanced Resistance to Host Antimicrobials. mBio 2018; 9:e00275-18. [PMID: 29588399 PMCID: PMC5874919 DOI: 10.1128/mbio.00275-18] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa causes chronic pulmonary infections in patients with cystic fibrosis (CF). P. aeruginosa mucoid conversion, defined by overproduction of the exopolysaccharide alginate, correlates with accelerated decline in CF patient lung function. Recalcitrance of the mucoid phenotype to clearance by antibiotics and the immune response is well documented. However, despite advantages conferred by mucoidy, mucoid variants often revert to a nonmucoid phenotype both in vitro and in vivo Mixed populations of mucoid isolates and nonmucoid revertants are recovered from CF lungs, suggesting a selective benefit for coexistence of these variants. In this study, cocultures of mucoid and nonmucoid variants exhibited enhanced resistance to two host antimicrobials: LL-37, a cationic antimicrobial peptide, and hydrogen peroxide (H2O2). Alginate production by mucoid isolates protected nonmucoid variants in consortia from LL-37, as addition of alginate exogenously to nonmucoid variants abrogated LL-37 killing. Conversely, nonmucoid revertants shielded mucoid variants from H2O2 stress via catalase (KatA) production, which was transcriptionally repressed by AlgT and AlgR, central regulators of alginate biosynthesis. Furthermore, extracellular release of KatA by nonmucoid revertants was dependent on lys, encoding an endolysin implicated in autolysis and extracellular DNA (eDNA) release. Overall, these data provide a rationale to study interactions of P. aeruginosa mucoid and nonmucoid variants as contributors to evasion of innate immunity and persistence within the CF lung.IMPORTANCEP. aeruginosa mucoid conversion within lungs of cystic fibrosis (CF) patients is a hallmark of chronic infection and predictive of poor prognosis. The selective benefit of mixed populations of mucoid and nonmucoid variants, often isolated from chronically infected CF patients, has not been explored. Here, we show that mixed-variant communities of P. aeruginosa demonstrate advantages in evasion of innate antimicrobials via production of shared goods: alginate and catalase. These data argue for therapeutically targeting multiple constituents (both mucoid and nonmucoid variants) within diversified P. aeruginosa communities in vivo, as these variants can differentially shield one another from components of the host response.
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Affiliation(s)
- Sankalp Malhotra
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
| | - Dominique H Limoli
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, USA
| | - Anthony E English
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
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17
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Limoli DH, Whitfield GB, Kitao T, Ivey ML, Davis MR, Grahl N, Hogan DA, Rahme LG, Howell PL, O'Toole GA, Goldberg JB. Pseudomonas aeruginosa Alginate Overproduction Promotes Coexistence with Staphylococcus aureus in a Model of Cystic Fibrosis Respiratory Infection. mBio 2017; 8:e00186-17. [PMID: 28325763 PMCID: PMC5362032 DOI: 10.1128/mbio.00186-17] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 02/22/2017] [Indexed: 01/30/2023] Open
Abstract
While complex intra- and interspecies microbial community dynamics are apparent during chronic infections and likely alter patient health outcomes, our understanding of these interactions is currently limited. For example, Pseudomonas aeruginosa and Staphylococcus aureus are often found to coinfect the lungs of patients with cystic fibrosis (CF), yet these organisms compete under laboratory conditions. Recent observations that coinfection correlates with decreased health outcomes necessitate we develop a greater understanding of these interbacterial interactions. In this study, we tested the hypothesis that P. aeruginosa and/or S. aureus adopts phenotypes that allow coexistence during infection. We compared competitive interactions of P. aeruginosa and S. aureus isolates from mono- or coinfected CF patients employing in vitro coculture models. P. aeruginosa isolates from monoinfected patients were more competitive toward S. aureus than P. aeruginosa isolates from coinfected patients. We also observed that the least competitive P. aeruginosa isolates possessed a mucoid phenotype. Mucoidy occurs upon constitutive activation of the sigma factor AlgT/U, which regulates synthesis of the polysaccharide alginate and dozens of other secreted factors, including some previously described to kill S. aureus Here, we show that production of alginate in mucoid strains is sufficient to inhibit anti-S. aureus activity independent of activation of the AlgT regulon. Alginate reduces production of siderophores, 2-heptyl-4-hydroxyquinolone-N-oxide (HQNO), and rhamnolipids-each required for efficient killing of S. aureus These studies demonstrate alginate overproduction may be an important factor driving P. aeruginosa coinfection with S. aureusIMPORTANCE Numerous deep-sequencing studies have revealed the microbial communities present during respiratory infections in cystic fibrosis (CF) patients are diverse, complex, and dynamic. We now face the challenge of determining the influence of these community dynamics on patient health outcomes and identifying candidate targets to modulate these interactions. We make progress toward this goal by determining that the polysaccharide alginate produced by mucoid strains of P. aeruginosa is sufficient to inhibit multiple secreted antimicrobial agents produced by this organism. Importantly, these secreted factors are required to outcompete S. aureus, when the microbes are grown in coculture; thus we propose a mechanism whereby mucoid P. aeruginosa can coexist with S. aureus Finally, the approach used here can serve as a platform to investigate the interactions among other CF pathogens.
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Affiliation(s)
- Dominique H Limoli
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Tomoe Kitao
- Department of Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, USA
- Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Shriners Hospitals for Children Boston, Boston, Massachusetts, USA
| | - Melissa L Ivey
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Michael R Davis
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Nora Grahl
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A Hogan
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Laurence G Rahme
- Department of Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, USA
- Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Shriners Hospitals for Children Boston, Boston, Massachusetts, USA
| | - P Lynne Howell
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - George A O'Toole
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Joanna B Goldberg
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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18
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Abstract
Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms.
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Rybtke M, Hultqvist LD, Givskov M, Tolker-Nielsen T. Pseudomonas aeruginosa Biofilm Infections: Community Structure, Antimicrobial Tolerance and Immune Response. J Mol Biol 2015; 427:3628-45. [DOI: 10.1016/j.jmb.2015.08.016] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 08/18/2015] [Accepted: 08/20/2015] [Indexed: 02/07/2023]
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Kong W, Zhao J, Kang H, Zhu M, Zhou T, Deng X, Liang H. ChIP-seq reveals the global regulator AlgR mediating cyclic di-GMP synthesis in Pseudomonas aeruginosa. Nucleic Acids Res 2015. [PMID: 26206672 PMCID: PMC4787818 DOI: 10.1093/nar/gkv747] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
AlgR is a key transcriptional regulator required for the expression of multiple virulence factors, including type IV pili and alginate in Pseudomonas aeruginosa. However, the regulon and molecular regulatory mechanism of AlgR have yet to be fully elucidated. Here, among 157 loci that were identified by a ChIP-seq assay, we characterized a gene, mucR, which encodes an enzyme that synthesizes the intracellular second messenger cyclic diguanylate (c-di-GMP). A ΔalgR strain produced lesser biofilm than did the wild-type strain, which is consistent with a phenotype controlled by c-di-GMP. AlgR positively regulates mucR via direct binding to its promoter. A ΔalgRΔmucR double mutant produced lesser biofilm than did the single ΔalgR mutant, demonstrating that c-di-GMP is a positive regulator of biofilm formation. AlgR controls the levels of c-di-GMP synthesis via direct regulation of mucR. In addition, the cognate sensor of AlgR, FimS/AlgZ, also plays an important role in P. aeruginosa virulence. Taken together, this study provides new insights into the AlgR regulon and reveals the involvement of c-di-GMP in the mechanism underlying AlgR regulation.
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Affiliation(s)
- Weina Kong
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Jingru Zhao
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Huaping Kang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Miao Zhu
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Tianhong Zhou
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Xin Deng
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Haihua Liang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
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21
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Whitfield GB, Marmont LS, Howell PL. Enzymatic modifications of exopolysaccharides enhance bacterial persistence. Front Microbiol 2015; 6:471. [PMID: 26029200 PMCID: PMC4432689 DOI: 10.3389/fmicb.2015.00471] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/29/2015] [Indexed: 12/25/2022] Open
Abstract
Biofilms are surface-attached communities of bacterial cells embedded in a self-produced matrix that are found ubiquitously in nature. The biofilm matrix is composed of various extracellular polymeric substances, which confer advantages to the encapsulated bacteria by protecting them from eradication. The matrix composition varies between species and is dependent on the environmental niche that the bacteria inhabit. Exopolysaccharides (EPS) play a variety of important roles in biofilm formation in numerous bacterial species. The ability of bacteria to thrive in a broad range of environmental settings is reflected in part by the structural diversity of the EPS produced both within individual bacterial strains as well as by different species. This variability is achieved through polymerization of distinct sugar moieties into homo- or hetero-polymers, as well as post-polymerization modification of the polysaccharide. Specific enzymes that are unique to the production of each polymer can transfer or remove non-carbohydrate moieties, or in other cases, epimerize the sugar units. These modifications alter the physicochemical properties of the polymer, which in turn can affect bacterial pathogenicity, virulence, and environmental adaptability. Herein, we review the diversity of modifications that the EPS alginate, the Pel polysaccharide, Vibrio polysaccharide, cepacian, glycosaminoglycans, and poly-N-acetyl-glucosamine undergo during biosynthesis. These are EPS produced by human pathogenic bacteria for which studies have begun to unravel the effect modifications have on their physicochemical and biological properties. The biological advantages these polymer modifications confer to the bacteria that produce them will be discussed. The expanding list of identified modifications will allow future efforts to focus on linking these modifications to specific biosynthetic genes and biofilm phenotypes.
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Affiliation(s)
- Gregory B Whitfield
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - Lindsey S Marmont
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - P Lynne Howell
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, Faculty of Medicine, University of Toronto Toronto, ON, Canada
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22
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Römling U, Kjelleberg S, Normark S, Nyman L, Uhlin BE, Åkerlund B. Microbial biofilm formation: a need to act. J Intern Med 2014; 276:98-110. [PMID: 24796496 DOI: 10.1111/joim.12242] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- U Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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23
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Jones CJ, Newsom D, Kelly B, Irie Y, Jennings LK, Xu B, Limoli DH, Harrison JJ, Parsek MR, White P, Wozniak DJ. ChIP-Seq and RNA-Seq reveal an AmrZ-mediated mechanism for cyclic di-GMP synthesis and biofilm development by Pseudomonas aeruginosa. PLoS Pathog 2014; 10:e1003984. [PMID: 24603766 PMCID: PMC3946381 DOI: 10.1371/journal.ppat.1003984] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 01/23/2014] [Indexed: 11/28/2022] Open
Abstract
The transcription factor AmrZ regulates genes important for P. aeruginosa virulence, including type IV pili, extracellular polysaccharides, and the flagellum; however, the global effect of AmrZ on gene expression remains unknown, and therefore, AmrZ may directly regulate many additional genes that are crucial for infection. Compared to the wild type strain, a ΔamrZ mutant exhibits a rugose colony phenotype, which is commonly observed in variants that accumulate the intracellular second messenger cyclic diguanylate (c-di-GMP). Cyclic di-GMP is produced by diguanylate cyclases (DGC) and degraded by phosphodiesterases (PDE). We hypothesized that AmrZ limits the intracellular accumulation of c-di-GMP through transcriptional repression of gene(s) encoding a DGC. In support of this, we observed elevated c-di-GMP in the ΔamrZ mutant compared to the wild type strain. Consistent with other strains that accumulate c-di-GMP, when grown as a biofilm, the ΔamrZ mutant formed larger microcolonies than the wild-type strain. This enhanced biofilm formation was abrogated by expression of a PDE. To identify potential target DGCs, a ChIP-Seq was performed and identified regions of the genome that are bound by AmrZ. RNA-Seq experiments revealed the entire AmrZ regulon, and characterized AmrZ as an activator or repressor at each binding site. We identified an AmrZ-repressed DGC-encoding gene (PA4843) from this cohort, which we named AmrZ dependent cyclase A (adcA). PAO1 overexpressing adcA accumulates 29-fold more c-di-GMP than the wild type strain, confirming the cyclase activity of AdcA. In biofilm reactors, a ΔamrZ ΔadcA double mutant formed smaller microcolonies than the single ΔamrZ mutant, indicating adcA is responsible for the hyper biofilm phenotype of the ΔamrZ mutant. This study combined the techniques of ChIP-Seq and RNA-Seq to define the comprehensive regulon of a bifunctional transcriptional regulator. Moreover, we identified a c-di-GMP mediated mechanism for AmrZ regulation of biofilm formation and chronicity. Pathogenic bacteria such as Pseudomonas aeruginosa utilize a wide variety of systems to sense and respond to the changing conditions during an infection. When a stress is sensed, signals are transmitted to impact expression of many genes that allow the bacterium to adapt to the changing conditions. AmrZ is a protein that regulates production of several virulence-associated gene products, though we predicted that its role in virulence was more expansive than previously described. Transcription factors such as AmrZ often affect the expression of a gene by binding and promoting or inhibiting expression of the target gene. Two global techniques were utilized to determine where AmrZ binds in the genome, and what effect AmrZ has once bound. This approach revealed that AmrZ represses the production of a signaling molecule called cyclic diguanylate, which is known to induce the formation of difficult to treat communities of bacteria called biofilms. This study also identified many novel targets of AmrZ to promote future studies of this regulator. Collectively, these data can be utilized to develop treatments to inhibit biofilm formation during devastating chronic infections.
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Affiliation(s)
- Christopher J. Jones
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America
- Department of Infection and Immunity and Center for Microbial Interface Biology, Ohio State University, Columbus, Ohio, United States of America
| | - David Newsom
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Benjamin Kelly
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Yasuhiko Irie
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Laura K. Jennings
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Binjie Xu
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Dominique H. Limoli
- Department of Infection and Immunity and Center for Microbial Interface Biology, Ohio State University, Columbus, Ohio, United States of America
| | - Joe J. Harrison
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Peter White
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Daniel J. Wozniak
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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24
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Hay ID, Wang Y, Moradali MF, Rehman ZU, Rehm BHA. Genetics and regulation of bacterial alginate production. Environ Microbiol 2014; 16:2997-3011. [DOI: 10.1111/1462-2920.12389] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 12/18/2013] [Accepted: 12/22/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Iain D. Hay
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Yajie Wang
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Mohammed F. Moradali
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Zahid U. Rehman
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Bernd H. A. Rehm
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology; Massey University; Palmerston North 4442 New Zealand
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25
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Sowmya R, Sachindra N. Evaluation of antioxidant activity of carotenoid extract from shrimp processing byproducts by in vitro assays and in membrane model system. Food Chem 2012. [DOI: 10.1016/j.foodchem.2012.02.147] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Alkawareek MY, Algwari QT, Gorman SP, Graham WG, O'Connell D, Gilmore BF. Application of atmospheric pressure nonthermal plasma for the in vitro eradication of bacterial biofilms. ACTA ACUST UNITED AC 2012; 65:381-4. [PMID: 22329678 DOI: 10.1111/j.1574-695x.2012.00942.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/16/2011] [Accepted: 02/06/2012] [Indexed: 12/01/2022]
Abstract
The use of atmospheric pressure nonthermal plasma represents an interesting and novel approach for the decontamination of surfaces colonized with microbial biofilms that exhibit enhanced tolerance to antimicrobial challenge. In this study, the influence of an atmospheric pressure nonthermal plasma jet, operated in a helium and oxygen gas mixture under ambient pressure, was evaluated against biofilms of Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Within < 4 min of plasma exposure, complete eradication of the two gram-positive bacterial biofilms was achieved. Although gram-negative biofilms required longer treatment time, their complete eradication was still possible with 10 min of exposure. Whilst this study provides useful proof of concept data on the use of atmospheric pressure plasmas for the eradication of bacterial biofilms in vitro, it also demonstrates the critical need for improved understanding of the mechanisms and kinetics related to such a potentially significant approach.
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27
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McCarty SM, Cochrane CA, Clegg PD, Percival SL. The role of endogenous and exogenous enzymes in chronic wounds: A focus on the implications of aberrant levels of both host and bacterial proteases in wound healing. Wound Repair Regen 2012; 20:125-36. [DOI: 10.1111/j.1524-475x.2012.00763.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sara M. McCarty
- Institute of Ageing and Chronic Disease; University of Liverpool; Liverpool; United Kingdom
| | - Christine A. Cochrane
- Institute of Ageing and Chronic Disease; University of Liverpool; Liverpool; United Kingdom
| | - Peter D. Clegg
- Institute of Ageing and Chronic Disease; University of Liverpool; Liverpool; United Kingdom
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Cuzzi B, Cescutti P, Furlanis L, Lagatolla C, Sturiale L, Garozzo D, Rizzo R. Investigation of bacterial resistance to the immune system response: cepacian depolymerisation by reactive oxygen species. Innate Immun 2012; 18:661-71. [PMID: 22278934 DOI: 10.1177/1753425911435954] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Reactive oxygen species (ROS) are part of the weapons used by the immune system to kill and degrade infecting microorganisms. Bacteria can produce macromolecules, such as polysaccharides, that are able to scavenge ROS. Species belonging to the Burkholderia cepacia complex are involved in serious lung infection in cystic fibrosis patients and produce a characteristic polysaccharide, cepacian. The interaction between ROS and bacterial polysaccharides was first investigated by killing experiments, where bacteria cells were incubated with sodium hypochlorite (NaClO) with and without prior incubation with cepacian. The results showed that the polysaccharide had a protective effect towards bacterial cells. Cepacian was then treated with different concentrations of NaClO and the course of reactions was followed by means of capillary viscometry. The degradation products were characterised by size-exclusion chromatography, NMR and mass spectrometry. The results showed that hypochlorite depolymerised cepacian, removed side chains and O-acetyl groups, but did not cleave the glycosidic bond between glucuronic acid and rhamnose. The structure of some oligomers produced by NaClO oxidation is reported.
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Affiliation(s)
- Bruno Cuzzi
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
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Mishra M, Byrd MS, Sergeant S, Azad AK, Parsek MR, McPhail L, Schlesinger LS, Wozniak DJ. Pseudomonas aeruginosa Psl polysaccharide reduces neutrophil phagocytosis and the oxidative response by limiting complement-mediated opsonization. Cell Microbiol 2011; 14:95-106. [PMID: 21951860 DOI: 10.1111/j.1462-5822.2011.01704.x] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Pseudomonas aeruginosa causes chronic lung infections in the airways of cystic fibrosis (CF) patients. Psl is an extracellular polysaccharide expressed by non-mucoid P. aeruginosa strains, which are believed to be initial colonizers. We hypothesized that Psl protects P. aeruginosa from host defences within the CF lung prior to their conversion to the mucoid phenotype. We discovered that serum opsonization significantly increased the production of reactive oxygen species (ROS) by neutrophils exposed to a psl-deficient mutant, compared with wild-type (WT) and Psl overexpressing strains (Psl(++)). Psl-deficient P. aeruginosa were internalized and killed by neutrophils and macrophages more efficiently than WT and Psl(++) variants. Deposition of complement components C3, C5 and C7 was significantly higher on psl-deficient strains compared with WT and Psl(++) bacteria. In an in vivo pulmonary competition assay, there was a 4.5-fold fitness advantage for WT over psl-deficient P. aeruginosa. Together, these data show that Psl inhibits efficient opsonization, resulting in reduced neutrophil ROS production, and decreased killing by phagocytes. This provides a survival advantage in vivo. Since phagocytes are critical in early recognition and control of infection, therapies aimed at Psl could improve the quality of life for patients colonized with P. aeruginosa.
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Affiliation(s)
- Meenu Mishra
- Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA
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30
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Rogers GB, Hoffman LR, Döring G. Novel concepts in evaluating antimicrobial therapy for bacterial lung infections in patients with cystic fibrosis. J Cyst Fibros 2011; 10:387-400. [PMID: 21775220 DOI: 10.1016/j.jcf.2011.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 06/04/2011] [Accepted: 06/17/2011] [Indexed: 10/17/2022]
Abstract
Cystic fibrosis (CF) patients suffer typically from bacterial infections of their airways. Whilst current antibiotic-based treatment of these infections has brought much benefit to patients, it has been difficult to make either direct or indirect assessments of the in vivo efficacy of any specific treatment used. Traditional culture-based assessment has for example been rarely used to determine the direct impact of therapy on the bacteria in the airways. Instead, the "success" of a treatment is most often gauged through measures of respiratory and general health. New culture-independent approaches though are emerging that offer much promise here however in allowing a more comprehensive evaluation of antimicrobial efficacy. These new methods offer an opportunity to examine bacterial outcomes rather than host outcomes alone. Application of these novel techniques in a systematic way will lead to the rationalisation and, likely greater still individualisation, of therapy for CF patients. This review discusses host and microbiological factors that may influence antibiotic efficacy. Moreover, the degree to which the inherent complexity of CF respiratory infections complicates the process of determining treatment impact and the need to identify more robust microbiological outcome measures will also be reviewed.
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Affiliation(s)
- Geraint B Rogers
- Molecular Microbiology Research Laboratory, King's College London, United Kingdom.
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Crabbé A, Pycke B, Van Houdt R, Monsieurs P, Nickerson C, Leys N, Cornelis P. Response of Pseudomonas aeruginosa PAO1 to low shear modelled microgravity involves AlgU regulation. Environ Microbiol 2010; 12:1545-64. [PMID: 20236169 DOI: 10.1111/j.1462-2920.2010.02184.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
As a ubiquitous environmental organism that is occasionally part of the human flora, Pseudomonas aeruginosa could pose a health hazard for the immunocompromised astronauts during long-term missions. Therefore, insights into the behaviour of P. aeruginosa under spaceflight conditions were gained using two spaceflight-analogue culture systems: the rotating wall vessel (RWV) and the random position machine (RPM). Microarray analysis of P. aeruginosa PAO1 grown in the low shear modelled microgravity (LSMMG) environment of the RWV, compared with the normal gravity control (NG), revealed an apparent regulatory role for the alternative sigma factor AlgU (RpoE-like). Accordingly, P. aeruginosa cultured in LSMMG exhibited increased alginate production and upregulation of AlgU-controlled transcripts, including those encoding stress-related proteins. The LSMMG increased heat and oxidative stress resistance and caused a decrease in the oxygen transfer rate of the culture. This study also showed the involvement of the RNA-binding protein Hfq in the LSMMG response, consistent with its previously identified role in the Salmonella LSMMG and spaceflight response. The global transcriptional response of P. aeruginosa grown in the RPM was highly similar to that in NG. Fluid mixing was assessed in both systems and is believed to be a pivotal factor contributing to transcriptional differences between RWV- and RPM-grown P. aeruginosa. This study represents the first step towards the identification of virulence mechanisms of P. aeruginosa activated in response to spaceflight-analogue conditions, and could direct future research regarding the risk assessment and prevention of Pseudomonas infections during spaceflight and in immunocompromised patients.
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Affiliation(s)
- Aurélie Crabbé
- Laboratory of Microbial Interactions, Department of Molecular and Cellular Interactions, Flanders Institute for Biotechnology (VIB), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
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33
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Pseudomonas aeruginosa alginate promotes Burkholderia cenocepacia persistence in cystic fibrosis transmembrane conductance regulator knockout mice. Infect Immun 2010; 78:984-93. [PMID: 20048042 DOI: 10.1128/iai.01192-09] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa, a major respiratory pathogen in cystic fibrosis (CF) patients, facilitates infection by other opportunistic pathogens. Burkholderia cenocepacia, which normally infects adolescent patients, encounters alginate elaborated by mucoid P. aeruginosa. To determine whether P. aeruginosa alginate facilitates B. cenocepacia infection in mice, cystic fibrosis transmembrane conductance regulator knockout mice were infected with B. cenocepacia strain BC7 suspended in either phosphate-buffered saline (BC7/PBS) or P. aeruginosa alginate (BC7/alginate), and the pulmonary bacterial load and inflammation were monitored. Mice infected with BC7/PBS cleared all of the bacteria within 3 days, and inflammation was resolved by day 5. In contrast, mice infected with BC7/alginate showed persistence of bacteria and increased cytokine levels for up to 7 days. Histological examination of the lungs indicated that there was moderate to severe inflammation and pneumonic consolidation in isolated areas at 5 and 7 days postinfection in the BC7/alginate group. Further, alginate decreased phagocytosis of B. cenocepacia by professional phagocytes both in vivo and in vitro. P. aeruginosa alginate also reduced the proinflammatory responses of CF airway epithelial cells and alveolar macrophages to B. cenocepacia infection. The observed effects are specific to P. aeruginosa alginate, because enzymatically degraded alginate or other polyuronic acids did not facilitate bacterial persistence. These observations suggest that P. aeruginosa alginate may facilitate B. cenocepacia infection by interfering with host innate defense mechanisms.
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Damron FH, Napper J, Teter MA, Yu HD. Lipotoxin F of Pseudomonas aeruginosa is an AlgU-dependent and alginate-independent outer membrane protein involved in resistance to oxidative stress and adhesion to A549 human lung epithelia. MICROBIOLOGY-SGM 2009; 155:1028-1038. [PMID: 19332805 DOI: 10.1099/mic.0.025833-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Chronic lung infection with P. aeruginosa and excessive neutrophil-associated inflammation are major causes of morbidity and mortality in patients with cystic fibrosis (CF). Overproduction of an exopolysaccharide known as alginate leads to the formation of mucoid biofilms that are resistant to antibiotics and host defences. Alginate overproduction or mucoidy is controlled by a stress-related ECF sigma factor AlgU/T. Mutation in the anti-sigma factor MucA is a known mechanism for conversion to mucoidy. Recently, we showed that inactivation of a kinase (KinB) in nonmucoid strain PAO1 results in overproduction of alginate. Here, we report the initial characterization of lipotoxin F (LptF, PA3692), an OmpA-like outer membrane protein that exhibited increased expression in the mucoid PAO1kinB mutant. The lipotoxin family of proteins has been previously shown to induce inflammation in lung epithelia, which may play a role in CF disease progression. Expression of LptF was observed to be AlgU-dependent and upregulated in CF isolates. Deletion of lptF from the kinB mutant had no effect on alginate production. Deletion of lptF from PAO1 caused a differential susceptibility to oxidants that can be generated by phagocytes. The lptF and algU mutants were more sensitive to hypochlorite than PAO1. However, the lptF mutant displayed increased resistance to hydrogen peroxide. LptF also contributed to adhesion to A549 human lung epithelial cells. Our data suggest that LptF is an outer membrane protein that may be important for P. aeruginosa survival in harsh environments, including lung colonization in CF.
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Affiliation(s)
- F Heath Damron
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
| | - Jennifer Napper
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
| | - M Allison Teter
- Department of Biology and Environmental Science, West Virginia Wesleyan College, Buckhannon, WV 26201, USA
| | - Hongwei D Yu
- Progenesis Technologies, LLC, Bldg 740, Rm 4136, Dow Technology Park, 3200 Kanawha Turnpike, South Charleston, WV 25303, USA.,Department of Pediatrics, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25701-3655, USA.,Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
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35
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Pseudomonas aeruginosa AlgR controls cyanide production in an AlgZ-dependent manner. J Bacteriol 2009; 191:2993-3002. [PMID: 19270096 DOI: 10.1128/jb.01156-08] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic infections in individuals suffering from the genetic disorder cystic fibrosis. In P. aeruginosa, the transcriptional regulator AlgR controls a variety of virulence factors, including alginate production, twitching motility, biofilm formation, quorum sensing, and hydrogen cyanide (HCN) production. In this study, the regulation of HCN production was examined. Strains lacking AlgR or the putative AlgR sensor AlgZ produced significantly less HCN than did a nonmucoid isogenic parent. In contrast, algR and algZ mutants showed increased HCN production in an alginate-producing (mucoid) background. HCN production was optimal in a 5% O2 environment. In addition, cyanide production was elevated in bacteria grown on an agar surface compared to bacteria grown in planktonic culture. A conserved AlgR phosphorylation site (aspartate at amino acid position 54), which is required for surface-dependent twitching motility but not alginate production, was found to be critical for cyanide production. Nuclease protection mapping of the hcnA promoter identified a new transcriptional start site required for HCN production. A subset of clinical isolates that lack this start site produced small amounts of cyanide. Taken together, these data show that the P. aeruginosa hcnA promoter contains three transcriptional start sites and that HCN production is regulated by AlgZ and AlgR and is maximal under microaerobic conditions when the organism is surface attached.
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36
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37
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Association between hypermutator phenotype, clinical variables, mucoid phenotype, and antimicrobial resistance in Pseudomonas aeruginosa. J Clin Microbiol 2008; 46:3491-3. [PMID: 18685006 DOI: 10.1128/jcm.00357-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The presence of hypermutator Pseudomonas aeruginosa was associated with poorer lung function in patients at the Adult West Midlands CF Unit. Mucoid isolates were more likely to be hypermutators. The presence of resistant mutant subpopulations was associated with hypermutator phenotype but was not good enough to be used as a test for this phenotype.
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38
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Chang MW, Toghrol F, Bentley WE. Toxicogenomic response to chlorination includes induction of major virulence genes in Staphylococcus aureus. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2007; 41:7570-7575. [PMID: 18044543 DOI: 10.1021/es070929k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Despite the widespread use of chlorination for microbial control in aqueous environments, cellular response mechanisms of human pathogens, such as Staphylococcus aureus, against chlorination remain unknown. In this work, genome-wide transcriptional analysis was performed to elucidate cellular response of S. aureusto hypochlorous acid, an active antimicrobial product of chlorination in aqueous solution. Our results suggest that hypochlorous acid repressed transcription of genes involved in cell wall synthesis, membrane transport, protein synthesis, and primary metabolism, while amino acid synthesis genes were induced. Furthermore, hypochlorous acid induced transcription of genes encoding major virulence factors of S. aureus, such as exotoxins, hemolysins, leukocidins, coagulases, and surface adhesion proteins, which all play essential roles in staphylococcal virulence. This work implies that chlorination may stimulate production of virulence factors, which provides new insight into host-pathogen interactions and effects of chlorine application for microbial control.
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Affiliation(s)
- Matthew Wook Chang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
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39
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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: 184] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [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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40
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Wood SR, Firoved AM, Ornatowski W, Mai T, Deretic V, Timmins GS. Nitrosative stress inhibits production of the virulence factor alginate in mucoid Pseudomonas aeruginosa. Free Radic Res 2007; 41:208-15. [PMID: 17364947 DOI: 10.1080/10715760601052610] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Alginate is a critical virulence factor contributing to the poor clinical prognosis associated with the conversion of Pseudomonas aeruginosa to mucoid phenotypes in cystic fibrosis (CF). An important mechanism of action is its ability to scavenge host innate-immune reactive species. We have previously analyzed the bacterial response to nitrosative stress by S-nitrosoglutathione (GSNO), a physiological NO radical donor with diminished levels in the CF lung. GSNO substantially increased bacterial nitrosative and oxidative defenses and so we hypothesized a similar increase in alginate production would occur. However, in mucoid P. aeruginosa, there was decreased expression of the majority of alginate synthetic genes. This microarray data was confirmed both by RT-PCR and at the functional level by direct measurements of alginate production. Our data suggest that the lowered levels of innate-immune nitrosative mediators (such as GSNO) in the CF lung exacerbate the effects of mucoid P. aeruginosa, by failing to suppress alginate biosynthesis.
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Affiliation(s)
- Simon R Wood
- College of Pharmacy, Toxicology Program, Health Sciences Center, University of New Mexico, Albuquerque, NM 87131, USA
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41
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Tart AH, Blanks MJ, Wozniak DJ. The AlgT-dependent transcriptional regulator AmrZ (AlgZ) inhibits flagellum biosynthesis in mucoid, nonmotile Pseudomonas aeruginosa cystic fibrosis isolates. J Bacteriol 2006; 188:6483-9. [PMID: 16952938 PMCID: PMC1595476 DOI: 10.1128/jb.00636-06] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is a microorganism associated with the disease cystic fibrosis. While environmental P. aeruginosa strains are generally nonmucoid and motile, isolates recovered from the cystic fibrosis lung frequently display a mucoid, nonmotile phenotype. This phenotypic conversion is mediated by the alternative sigma factor AlgT. Previous work has shown that repression of fleQ by AlgT accounts for the loss of flagellum biosynthesis in these strains. Here, we elucidate the mechanism involved in the AlgT-mediated control of fleQ. Electrophoretic mobility shift assays using purified AlgT and extracts derived from isogenic AlgT(+) and AlgT(-) strains revealed that AlgT inhibits fleQ indirectly. We observed that the AlgT-dependent transcriptional regulator AmrZ interacts directly with the fleQ promoter. To determine whether AmrZ functions as a repressor of fleQ, we mutated amrZ in the mucoid, nonmotile P. aeruginosa strain FRD1. Unlike the parental strain, the amrZ mutant was nonmucoid and motile. Complementation of the mutant with amrZ restored the mucoid, nonmotile phenotype. Thus, our data show that AlgT inhibits flagellum biosynthesis in mucoid, nonmotile P. aeruginosa cystic fibrosis isolates by promoting expression of AmrZ, which subsequently represses fleQ. Since fleQ directly or indirectly controls the expression of almost all flagellar genes, its repression ultimately leads to the loss of flagellum biosynthesis.
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Affiliation(s)
- Anne H Tart
- Department of Microbiology and Immunology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1064, USA
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42
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Chang W, Small DA, Toghrol F, Bentley WE. Global transcriptome analysis of Staphylococcus aureus response to hydrogen peroxide. J Bacteriol 2006; 188:1648-59. [PMID: 16452450 PMCID: PMC1367260 DOI: 10.1128/jb.188.4.1648-1659.2006] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus responds with protective strategies against phagocyte-derived reactive oxidants to infect humans. Herein, we report the transcriptome analysis of the cellular response of S. aureus to hydrogen peroxide-induced oxidative stress. The data indicate that the oxidative response includes the induction of genes involved in virulence, DNA repair, and notably, anaerobic metabolism.
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Affiliation(s)
- Wook Chang
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park 20742, USA
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43
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Leid JG, Willson CJ, Shirtliff ME, Hassett DJ, Parsek MR, Jeffers AK. The exopolysaccharide alginate protects Pseudomonas aeruginosa biofilm bacteria from IFN-gamma-mediated macrophage killing. THE JOURNAL OF IMMUNOLOGY 2006; 175:7512-8. [PMID: 16301659 DOI: 10.4049/jimmunol.175.11.7512] [Citation(s) in RCA: 336] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ability of Pseudomonas aeruginosa to form biofilms and cause chronic infections in the lungs of cystic fibrosis patients is well documented. Numerous studies have revealed that P. aeruginosa biofilms are highly refractory to antibiotics. However, dramatically fewer studies have addressed P. aeruginosa biofilm resistance to the host's immune system. In planktonic, unattached (nonbiofilm) P. aeruginosa, the exopolysaccharide alginate provides protection against a variety of host factors yet the role of alginate in protection of biofilm bacteria is unclear. To address this issue, we tested wild-type strains PAO1, PA14, the mucoid cystic fibrosis isolate, FRD1 (mucA22+), and the respective isogenic mutants which lacked the ability to produce alginate, for their susceptibility to human leukocytes in the presence and absence of IFN-gamma. Human leukocytes, in the presence of recombinant human IFN-gamma, killed biofilm bacteria lacking alginate after a 4-h challenge at 37 degrees C. Bacterial killing was dependent on the presence of IFN-gamma. Killing of the alginate-negative biofilm bacteria was mediated through mononuclear cell phagocytosis since treatment with cytochalasin B, which prevents actin polymerization, inhibited leukocyte-specific bacterial killing. By direct microscopic observation, phagocytosis of alginate-negative biofilm bacteria was significantly increased in the presence of IFN-gamma vs all other treatments. Addition of exogenous, purified alginate to the alginate-negative biofilms restored resistance to human leukocyte killing. Our results suggest that although alginate may not play a significant role in bacterial attachment, biofilm development, and formation, it may play an important role in protecting mucoid P. aeruginosa biofilm bacteria from the human immune system.
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Affiliation(s)
- Jeff G Leid
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA.
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44
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Bylund J, Burgess LA, Cescutti P, Ernst RK, Speert DP. Exopolysaccharides from Burkholderia cenocepacia inhibit neutrophil chemotaxis and scavenge reactive oxygen species. J Biol Chem 2005; 281:2526-32. [PMID: 16316987 DOI: 10.1074/jbc.m510692200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacteria belonging to the Burkholderia cepacia complex are important opportunistic pathogens in compromised hosts, particularly patients with cystic fibrosis or chronic granulomatous disease. Isolates of B. cepacia complex may produce large amounts of exopolysaccharides (EPS) that endow the bacteria with a mucoid phenotype and appear to facilitate bacterial persistence during infection. We showed that EPS from a clinical B. cenocepacia isolate interfered with the function of human neutrophils in vitro; it inhibited chemotaxis and production of reactive oxygen species (ROS), both essential components of innate neutrophil-mediated host defenses. These inhibitory effects were not due to cytotoxicity or interference with intracellular calcium signaling. EPS also inhibited enzymatic generation of ROS in cell-free systems, indicating that it scavenges these bactericidal products. B. cenocepacia EPS is structurally distinct from Pseudomonas aeruginosa alginate, yet they share the capacity to scavenge ROS and inhibit chemotaxis. These properties could explain why the two bacterial species resist clearance from the infected cystic fibrosis lung.
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Affiliation(s)
- Johan Bylund
- Department of Pediatrics, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
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45
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Douthit SA, Dlakic M, Ohman DE, Franklin MJ. Epimerase active domain of Pseudomonas aeruginosa AlgG, a protein that contains a right-handed beta-helix. J Bacteriol 2005; 187:4573-83. [PMID: 15968068 PMCID: PMC1151786 DOI: 10.1128/jb.187.13.4573-4583.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The polysaccharide alginate forms a protective capsule for Pseudomonas aeruginosa during chronic pulmonary infections. The structure of alginate, a linear polymer of beta1-4-linked O-acetylated d-mannuronate (M) and l-guluronate (G), is important for its activity as a virulence factor. Alginate structure is mediated by AlgG, a periplasmic C-5 mannuronan epimerase. AlgG also plays a role in protecting alginate from degradation by the periplasmic alginate lyase AlgL. Here, we show that the C-terminal region of AlgG contains a right-handed beta-helix (RHbetaH) fold, characteristic of proteins with the carbohydrate-binding and sugar hydrolase (CASH) domain. When modeled based on pectate lyase C of Erwinia chrysanthemi, the RHbetaH of AlgG has a long shallow groove that may accommodate alginate, similar to protein/polysaccharide interactions of other CASH domain proteins. The shallow groove contains a 324-DPHD motif that is conserved among AlgG and the extracellular mannuronan epimerases of Azotobacter vinelandii. Point mutations in this motif disrupt mannuronan epimerase activity but have no effect on alginate secretion. The D324A mutation has a dominant negative phenotype, suggesting that the shallow groove in AlgG contains the catalytic face for epimerization. Other conserved motifs of the epimerases, 361-NNRSYEN and 381-NLVAYN, are predicted to lie on the opposite side of the RHbetaH from the catalytic center. Point mutations N362A, N367A, and V383A result in proteins that do not protect alginate from AlgL, suggesting that these mutant proteins are not properly folded or not inserted into the alginate biosynthetic scaffold. These motifs are likely involved in asparagine and hydrophobic stacking, required for structural integrity of RHbetaH proteins, rather than for mannuronan catalysis. The results suggest that the AlgG RHbetaH protects alginate from degradation by AlgL by channeling the alginate polymer through the proposed alginate biosynthetic scaffold while epimerizing approximately every second d-mannuronate residue to l-guluronate along the epimerase catalytic face.
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Affiliation(s)
- Stephanie A Douthit
- Department of Microbiology, 109 Lewis Hall, Montana State University, Bozeman, MT 59717, USA
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46
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Chang W, Small DA, Toghrol F, Bentley WE. Microarray analysis of toxicogenomic effects of peracetic acid on Pseudomonas aeruginosa. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:5893-9. [PMID: 16124331 DOI: 10.1021/es0503534] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Hospital-acquired (nosocomial) infection (HAI) represents a serious threat to public health, both in terms of human casualty and in terms of economic impact. On an annual basis, 2 million individuals require prolonged hospitalization, and an estimated 90 000 patients die due to HAI. Economic damages are reported to exceed $4.5 billion, annually. While many disinfectants, including peracetic acid, have been employed to eradicate infectious bacteria, a lack of understanding their mode of action and the corresponding defense mechanisms hinders successful antimicrobial application. We report here the first transcriptome analysis of the response of Pseudomonas aeruginosa, a pathogen infecting those with cystic fibrosis, upon 20 min exposure to a sublethal concentration (1 mM) of peracetic acid. As a result, we identified that 570 out of a total of 5570 P. aeruginosa genes showed statistically significant transcript level changes. Our findings indicate that (i) many genes associated with cellular protective processes were induced, (ii) the transcription of genes involved in primary metabolic pathways was repressed, and (iii) the transcription of genes encoding membrane proteins and small molecule transporters was altered. We also observed that genes within operons were highly cotranscribed in this study. Finally, this global transcriptional profile can help identify signature genes that are also activated with other oxidative disinfectants, which may be used to design new more effective treatments or more efficaciously apply existing compounds.
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Affiliation(s)
- Wook Chang
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, Maryland 20742, USA
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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] [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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Bylund J, Campsall PA, Ma RC, Conway BAD, Speert DP. Burkholderia cenocepaciaInduces Neutrophil Necrosis in Chronic Granulomatous Disease. THE JOURNAL OF IMMUNOLOGY 2005; 174:3562-9. [PMID: 15749893 DOI: 10.4049/jimmunol.174.6.3562] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Burkholderia cepacia complex is a life-threatening group of pathogens for patients with chronic granulomatous disease (CGD), whose phagocytes are unable to produce reactive oxygen species (ROS). Unlike other CGD pathogens, B. cepacia complex is particularly virulent, characteristically causing septicemia, and is the bacterial species responsible for most fatalities in these patients. We found that a nonmucoid Burkholderia cenocepacia (a predominant species in the B. cepacia complex) isolate was readily ingested by normal human neutrophils under nonopsonic conditions and promoted apoptosis in these cells. The proapoptotic effect was not due to secreted bacterial products, but was dependent on bacterial viability. Phagocytosis was associated with a robust production of ROS, and the apoptotic neutrophils could be effectively cleared by monocyte-derived macrophages. The proapoptotic effect of B. cenocepacia was independent of ROS production because neutrophils from CGD patients were rendered apoptotic to a similar degree as control cells after challenge. More importantly, neutrophils from CGD patients, but not from normal individuals, were rendered necrotic after phagocytosis of B. cenocepacia. The extreme virulence of B. cepacia complex bacteria in CGD, but not in immunocompetent hosts, could be due to its necrotic potential in the absence of ROS.
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Affiliation(s)
- Johan Bylund
- Department of Pediatrics, University of British Columbia, British Columbia Research Institute for Children's and Women's Health, Vancouver, British Columbia, Canada
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Robles-Price A, Wong TY, Sletta H, Valla S, Schiller NL. AlgX is a periplasmic protein required for alginate biosynthesis in Pseudomonas aeruginosa. J Bacteriol 2004; 186:7369-77. [PMID: 15489449 PMCID: PMC523204 DOI: 10.1128/jb.186.21.7369-7377.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alginate, an exopolysaccharide produced by Pseudomonas aeruginosa, provides the bacterium with a selective advantage that makes it difficult to eradicate from the lungs of cystic fibrosis (CF) patients. Previous studies identified a gene, algX, within the alginate biosynthetic gene cluster on the P. aeruginosa chromosome. By probing cell fractions with anti-AlgX antibodies in a Western blot, AlgX was localized within the periplasm. Consistent with these results is the presence of a 26-amino-acid signal sequence. To examine the requirement for AlgX in alginate biosynthesis, part of algX in P. aeruginosa strain FRD1::pJLS3 was replaced with a nonpolar gentamicin resistance cassette. The resulting algXDelta::Gm mutant was verified by PCR and Western blot analysis and was phenotypically nonmucoid (non-alginate producing). The algXDelta::Gm mutant was restored to the mucoid phenotype with wild-type P. aeruginosa algX provided on a plasmid. The algXDelta::Gm mutant was found to secrete dialyzable oligouronic acids of various lengths. Mass spectroscopy and Dionex chromatography indicated that the dialyzable uronic acids are mainly mannuronic acid dimers resulting from alginate lyase (AlgL) degradation of polymannuronic acid. These studies suggest that AlgX is part of a protein scaffold that surrounds and protects newly formed polymers from AlgL degradation as they are transported within the periplasm for further modification and eventual transport out of the cell.
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Affiliation(s)
- Antonette Robles-Price
- Division of Biomedical Sciences, University of California, Riverside, CA 92521-0121, USA
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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] [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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