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Badillo-Larios NS, Turrubiartes-Martínez EA, Layseca-Espinosa E, González-Amaro R, Pérez-González LF, Niño-Moreno P. Interesting Cytokine Profile Caused by Clinical Strains of Pseudomonas aeruginosa MDR Carrying the exoU Gene. Int J Microbiol 2024; 2024:2748842. [PMID: 38974708 PMCID: PMC11227949 DOI: 10.1155/2024/2748842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 07/09/2024] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen in HAIs with two facets: the most studied is the high rate of antimicrobial resistance, and the less explored is the long list of virulence factors it possesses. This study aimed to characterize the virulence genes carried by strains as well as the profile of cytokines related to inflammation, according to the resistance profile presented. This study aims to identify the virulence factors associated with MDR strains, particularly those resistant to carbapenems, and assess whether there is a cytokine profile that correlates with these characteristics. As methodology species were identified by classical microbiological techniques and confirmed by molecular biology, resistance levels were determined by the minimum inhibitory concentration and identification of MDR strains. Virulence factor genotyping was performed using PCR. In addition, biofilm production was assessed using crystal violet staining. Finally, the strains were cocultured with PBMC, and cell survival and the cytokines IL-1β, IL-6, IL-10, IL-8, and TNF-α were quantified using flow cytometry. Bacteremia and nosocomial pneumonia in adults are the most frequent types of infection. In the toxigenic aspect, genes corresponding to the type III secretion system were present in at least 50% of cases. In addition, PBMC exposed to strains of four different categories according to their resistance and toxicity showed a differential pattern of cytokine expression, a decrease in IL-10, IL-6, and IL-8, and an over-secretion of IL-1b. In conclusion, the virulence genes showed a differentiated appearance for the two most aggressive exotoxins of T3SS (exoU and exoS) in multidrug-resistant strains. Moreover, the cytokine profile displays a low expression of cytokines with anti-inflammatory and proinflammatory effects in strains carrying the exoU gene.
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Affiliation(s)
- Nallely S. Badillo-Larios
- Center of Research in Health Sciences and BiomedicineFaculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
| | - Edgar Alejandro Turrubiartes-Martínez
- Center of Research in Health Sciences and BiomedicineFaculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
- Laboratory of Hematology, Faculty of Chemical SciencesAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
| | - Esther Layseca-Espinosa
- Center of Research in Health Sciences and BiomedicineFaculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
- Faculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
| | - Roberto González-Amaro
- Center of Research in Health Sciences and BiomedicineFaculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
- Faculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
| | - Luis Fernando Pérez-González
- Faculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
- Central Hospital Dr. Ignacio Morones Prieto, San Luis Potosi, Mexico
| | - Perla Niño-Moreno
- Center of Research in Health Sciences and BiomedicineFaculty of MedicineAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
- Genetics LaboratoryFaculty of Chemical SciencesAutonomous University of San Luis Potosi, San Luis Potosi, Mexico
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2
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Wu X, Jie F, Li P, Zhuo C, Pan W, Zhong N, Li C, Chen L. Active immunization with Pseudomonas aeruginosa vaccine protects mice from secondary Pseudomonas aeruginosa challenge post-influenza virus infection. J Thorac Dis 2023; 15:22-32. [PMID: 36794141 PMCID: PMC9922597 DOI: 10.21037/jtd-22-1012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 01/06/2023] [Indexed: 01/19/2023]
Abstract
Background Influenza virus infection complicated by secondary bacterial pneumonia contributes significantly to death during seasonal or pandemic influenza. Secondary infection of Pseudomonas aeruginosa (P. aeruginosa) in influenza virus-infected patients contributes to morbidity and mortality. Methods Mice were first infected with PR8 influenza virus, followed by a secondary infection of P. aeruginosa. Body weights and survival rate of mice was monitored daily over 20 days. Bronchoalveolar lavage fluids (BALFs) and lung homogenates were harvested for measuring bacterial titers. Lung tissue section slides were stained with hematoxylin and eosin for microscopic observation. After vaccination with inactivated P. aeruginosa cells or recombinant PcrV protein, the mice were subjected to PR8 influenza virus infection followed by a secondary infection of a P. aeruginosa. The inhibition against P. aeruginosa of serum was evaluated by detecting the growth of P. aeruginosa in broth containing diluted sera. Results The prior influenza infection greatly enhanced the susceptibility to secondary infection of P. aeruginosa and increased morbidity and mortality in mice. Active immunization with inactivated P. aeruginosa cells could protect mice from secondary P. aeruginosa challenge in influenza virus infected mice. Conclusions To develop an effective P. aeruginosa vaccine might be a promising strategy to decrease the threat of secondary P. aeruginosa infection in influenza patients.
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Affiliation(s)
- Xiaofeng Wu
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Feilong Jie
- Department of Respiratory Medicine, Gaozhou People’s Hospital, Gaozhou, China
| | - Pingchao Li
- Guangdong Laboratory of Computational Biomedicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Chao Zhuo
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Weiqi Pan
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Nanshan Zhong
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Chufang Li
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Ling Chen
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China;,Guangdong Laboratory of Computational Biomedicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
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3
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Hardy KS, Tessmer MH, Frank DW, Audia JP. Perspectives on the Pseudomonas aeruginosa Type III Secretion System Effector ExoU and Its Subversion of the Host Innate Immune Response to Infection. Toxins (Basel) 2021; 13:880. [PMID: 34941717 PMCID: PMC8708460 DOI: 10.3390/toxins13120880] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/19/2021] [Accepted: 12/04/2021] [Indexed: 12/02/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic, Gram-negative pathogen and an important cause of hospital acquired infections, especially in immunocompromised patients. Highly virulent P. aeruginosa strains use a type III secretion system (T3SS) to inject exoenzyme effectors directly into the cytoplasm of a target host cell. P. aeruginosa strains that express the T3SS effector, ExoU, associate with adverse outcomes in critically ill patients with pneumonia, owing to the ability of ExoU to rapidly damage host cell membranes and subvert the innate immune response to infection. Herein, we review the structure, function, regulation, and virulence characteristics of the T3SS effector ExoU, a highly cytotoxic phospholipase A2 enzyme.
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Affiliation(s)
- Kierra S. Hardy
- Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile, AL 36608, USA;
- Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL 36608, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Maxx H. Tessmer
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA;
| | - Dara W. Frank
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jonathon P. Audia
- Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile, AL 36608, USA;
- Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL 36608, USA
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4
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Shaw E, Wuest WM. Virulence attenuating combination therapy: a potential multi-target synergy approach to treat Pseudomonas aeruginosa infections in cystic fibrosis patients. RSC Med Chem 2020; 11:358-369. [PMID: 33479641 PMCID: PMC7580779 DOI: 10.1039/c9md00566h] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 02/06/2020] [Indexed: 12/15/2022] Open
Abstract
The World Health Organization considers the discovery of new treatments for P. aeruginosa a top priority. Virulence attenuating combination therapy (VACT) is a pragmatic strategy to improve bacterial clearance, repurpose outmoded antibiotics, improve drug efficacy at lower doses, and reduce the evolution of resistance. In vitro and in vivo studies have shown that adding a quorum sensing inhibitor or an extracellular polymeric substance repressor to classical antibiotics synergistically improves antipseudomonal activity. This review highlights why VACT could specifically benefit cystic fibrosis patients harboring chronic P. aeruginosa infections, outlines the current landscape of synergistic combinations between virulence-targeting small-molecules and anti-pseudomonal drugs, and suggests future directions for VACT research.
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Affiliation(s)
- Elana Shaw
- Department of Chemistry , Emory University , 1515 Dickey Drive , Atlanta , Georgia 30322 , USA .
| | - William M Wuest
- Department of Chemistry , Emory University , 1515 Dickey Drive , Atlanta , Georgia 30322 , USA .
- Emory Antibiotic Resistance Center , Emory University School of Medicine , 201 Dowman Drive , Atlanta , Georgia 30322 , USA
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5
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Abstract
PURPOSE OF REVIEW This review details the management of Pseudomonas aeruginosa infections covering both current and future treatment options that are and may be available for the clinicians. RECENT FINDINGS Pseudomonas aeruginosa infections are a great concern in hospital-acquired infections with very limited therapeutic options. The increasing antibiotic resistance has led to a need for different treatment choices that range from the use of new antibiotics to new nonantibiotic alternative agents to kill or disarm the pathogen. SUMMARY New molecules such as ceftolozane-tazobactam, ceftazidime-avibactam, and imipenem-relebactam have shown an adequate activity against P. aeruginosa, especially against multidrug resistance strains. Other nonantibiotic alternative treatments, such as antibodies, bacteriocins or phage therapy, have shown promising results, but future clinical studies are needed.
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6
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Ruffin M, Brochiero E. Repair Process Impairment by Pseudomonas aeruginosa in Epithelial Tissues: Major Features and Potential Therapeutic Avenues. Front Cell Infect Microbiol 2019; 9:182. [PMID: 31214514 PMCID: PMC6554286 DOI: 10.3389/fcimb.2019.00182] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 05/13/2019] [Indexed: 01/13/2023] Open
Abstract
Epithelial tissues protecting organs from the environment are the first-line of defense against pathogens. Therefore, efficient repair mechanisms after injury are crucial to maintain epithelial integrity. However, these healing processes can be insufficient to restore epithelial integrity, notably in infectious conditions. Pseudomonas aeruginosa infections in cutaneous, corneal, and respiratory tract epithelia are of particular concern because they are the leading causes of hospitalizations, disabilities, and deaths worldwide. Pseudomonas aeruginosa has been shown to alter repair processes, leading to chronic wounds and infections. Because of the current increase in the incidence of multi-drug resistant isolates of P. aeruginosa, complementary approaches to decrease the negative impact of these bacteria on epithelia are urgently needed. Here, we review the recent advances in the understanding of the impact of P. aeruginosa infections on the integrity and repair mechanisms of alveolar, airway, cutaneous and corneal epithelia. Potential therapeutic avenues aimed at counteracting this deleterious impact of infection are also discussed.
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Affiliation(s)
- Manon Ruffin
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.,Département de Médecine, Université de Montréal, Montréal, QC, Canada.,INSERM, Centre de Recherche Saint-Antoine, CRSA, Sorbonne Université, Paris, France
| | - Emmanuelle Brochiero
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.,Département de Médecine, Université de Montréal, Montréal, QC, Canada
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7
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Fujiwara K, Iwanami T, Fujikawa T. Alterations of Candidatus Liberibacter asiaticus-Associated Microbiota Decrease Survival of Ca. L. asiaticus in in vitro Assays. Front Microbiol 2018; 9:3089. [PMID: 30622518 PMCID: PMC6308922 DOI: 10.3389/fmicb.2018.03089] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/29/2018] [Indexed: 11/28/2022] Open
Abstract
Phloem-inhabiting bacterial phytopathogens often have smaller genomes than other bacterial phytopathogens. It is thought that they depend on both other phloem microbiota and phloem nutrients for colonization of the host. However, the mechanism underlying associations between phloem-inhabiting phytopathogens and other phloem microbiota are poorly understood. Here, we demonstrate that the survival of Candidatus Liberibacter asiaticus (CLas), a cause of huanglongbing (citrus greening disease), depends on interplay with a specific subset of CLas-associated microbiota. CLas was not susceptible to oxytetracycline in vitro. However, oxytetracycline treatment eliminated a particular sub-community dominated by the Comamonadaceae, Flavobacteriaceae, Microbacteriaceae, and Pseudomonadaceae, decreasing CLas survival. We speculate that CLas uses ecological services derived from CLas-associated microbiota to colonize the host and to construct a pathogen-associated community that stimulates disease development.
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Affiliation(s)
- Kazuki Fujiwara
- Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Koshi, Japan
| | - Toru Iwanami
- Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Takashi Fujikawa
- Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization, Tsukuba, Japan
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8
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Gagné-Thivierge C, Kukavica-Ibrulj I, Filion G, Dekimpe V, Tan SGE, Vincent AT, Déziel É, Levesque RC, Charette SJ. A multi-host approach to identify a transposon mutant of Pseudomonas aeruginosa LESB58 lacking full virulence. BMC Res Notes 2018; 11:198. [PMID: 29580289 PMCID: PMC5870910 DOI: 10.1186/s13104-018-3308-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/20/2018] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Pseudomonas aeruginosa is an opportunistic bacterial pathogen well known to cause chronic lung infections in individuals with cystic fibrosis (CF). Some strains adapted to this particular niche show distinct phenotypes, such as biofilm hyperproduction. It is necessary to study CF clinical P. aeruginosa isolates, such as Liverpool Epidemic Strains (LES), to acquire a better understanding of the key genes essential for in vivo maintenance and the major virulence mechanisms involved in CF lung infections. Previously, a library of 9216 mutants of the LESB58 strain were generated by signature-tagged mutagenesis (STM) and screened in the rat model of chronic lung infection, allowing the identification of 163 STM mutants showing defects in in vivo maintenance. RESULTS In the present study, these 163 mutants were successively screened in two additional surrogate host models (the amoeba and the fruit fly). The STM PALES_11731 mutant was the unique non-virulent in the three hosts. A competitive index study in rat lungs confirmed that the mutant was 20-fold less virulent than the wild-type strain. This study demonstrated the pertinence to use a multi-host approach to study the genetic determinants of P. aeruginosa strains infecting CF patients.
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Affiliation(s)
- Cynthia Gagné-Thivierge
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, QC, Canada
| | - Irena Kukavica-Ibrulj
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada.,Département de microbiologie, infectiologie et immunologie, Faculté de Médecine, Université Laval, Quebec City, QC, Canada
| | - Geneviève Filion
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, QC, Canada
| | | | - Sok Gheck E Tan
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, QC, Canada
| | - Antony T Vincent
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, QC, Canada
| | - Éric Déziel
- INRS-Institut Armand Frappier, Laval, QC, Canada
| | - Roger C Levesque
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada.,Département de microbiologie, infectiologie et immunologie, Faculté de Médecine, Université Laval, Quebec City, QC, Canada
| | - Steve J Charette
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada. .,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada. .,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Quebec City, QC, Canada.
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9
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Pseudomonas aeruginosa Exolysin promotes bacterial growth in lungs, alveolar damage and bacterial dissemination. Sci Rep 2017; 7:2120. [PMID: 28522850 PMCID: PMC5437091 DOI: 10.1038/s41598-017-02349-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/10/2017] [Indexed: 11/18/2022] Open
Abstract
Exolysin (ExlA) is a recently-identified pore-forming toxin secreted by a subset of Pseudomonas aeruginosa strains identified worldwide and devoid of Type III secretion system (T3SS), a major virulence factor. Here, we characterized at the ultrastructural level the lesions caused by an ExlA-secreting strain, CLJ1, in mouse infected lungs. CLJ1 induced necrotic lesions in pneumocytes and endothelial cells, resulting in alveolo-vascular barrier breakdown. Ectopic expression of ExlA in an exlA-negative strain induced similar tissue injuries. In addition, ExlA conferred on bacteria the capacity to proliferate in lungs and to disseminate in secondary organs, similar to bacteria possessing a functional T3SS. CLJ1 did not promote a strong neutrophil infiltration in the alveoli, owing to the weak pro-inflammatory cytokine reaction engendered by the strain. However, CLJ1 was rapidly eliminated from the blood in a bacteremia model, suggesting that it can be promptly phagocytosed by immune cells. Together, our study ascribes to ExlA-secreting bacteria the capacity to proliferate in the lung and to damage pulmonary tissues, thereby promoting metastatic infections, in absence of substantial immune response exacerbation.
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10
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Colmer-Hamood JA, Dzvova N, Kruczek C, Hamood AN. In Vitro Analysis of Pseudomonas aeruginosa Virulence Using Conditions That Mimic the Environment at Specific Infection Sites. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 142:151-91. [PMID: 27571695 DOI: 10.1016/bs.pmbts.2016.05.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes chronic lung infection in patients with cystic fibrosis (CF) and acute systemic infections in severely burned patients and immunocompromised patients including cancer patients undergoing chemotherapy and HIV infected individuals. In response to the environmental conditions at specific infection sites, P. aeruginosa expresses certain sets of cell-associated and extracellular virulence factors that produce tissue damage. Analyzing the mechanisms that govern the production of these virulence factors in vitro requires media that closely mimic the environmental conditions within the infection sites. In this chapter, we review studies based on media that closely resemble three in vivo conditions, the thick mucus accumulated within the lung alveoli of CF patients, the serum-rich wound bed and the bloodstream. Media resembling the CF alveolar mucus include standard laboratory media supplemented with sputum obtained from CF patients as well as prepared synthetic mucus media formulated to contain the individual components of CF sputum. Media supplemented with serum or individual serum components have served as surrogates for the soluble host components of wound infections, while whole blood has been used to investigate the adaptation of pathogens to the bloodstream. Studies using these media have provided valuable information regarding P. aeruginosa gene expression in different host environments as varying sets of genes were differentially regulated during growth in each medium. The unique effects observed indicate the essential role of these in vitro media that closely mimic the in vivo conditions in providing accurate information regarding the pathogenesis of P. aeruginosa infections.
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Affiliation(s)
- J A Colmer-Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States; Department of Medical Education, Texas Tech University Health Sciences Center, Lubbock, TX, United States.
| | - N Dzvova
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - C Kruczek
- Honors College, Texas Tech University, Lubbock, TX, United States
| | - A N Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States; Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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11
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Chatterjee R, Mondal A, Basu A, Datta S. Transition of phosphopantetheine adenylyltransferase from catalytic to allosteric state is characterized by ternary complex formation in Pseudomonas aeruginosa. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:773-86. [DOI: 10.1016/j.bbapap.2016.03.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/02/2016] [Accepted: 03/28/2016] [Indexed: 01/28/2023]
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12
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Guillemot L, Medina M, Pernet E, Leduc D, Chignard M, Touqui L, Wu Y. Cytosolic phospholipase A2α enhances mouse mortality induced by Pseudomonas aeruginosa pulmonary infection via interleukin 6. Biochimie 2014; 107 Pt A:95-104. [PMID: 25201511 DOI: 10.1016/j.biochi.2014.08.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/29/2014] [Indexed: 12/19/2022]
Abstract
Pseudomonas aeruginosa pulmonary infection is a leading cause of death in numerous diseases such as cystic fibrosis (CF). The host cytosolic phospholipase A2α (cPLA2α) releases lipid mediators that play an important role in the pathogenesis of diseases, but its role in lung injury induced by P. aeruginosa infection is still obscure. Using an animal model of P. aeruginosa lung infection, we showed that the CHA strain of P. aeruginosa was more potent than the PAK strain in inducing mouse mortality and lung injury, and that both mouse mortality and lung injury were reduced in cPLA2α(-/-) mice as compared to cPLA2α(+/+) mice. This was accompanied by decreased levels of IL6 but not other inflammatory cytokines (IL1β, KC and TNFα) in the bronchoalveolar lavage fluids (BALFs) of cPLA2α(-/-) mice. Given that CFTR(-/-) mice exhibit increased cPLA2α activation in the lung, the role of cPLA2α was further examined in this lung infection model. Compared to littermates, P. aeruginosa infection caused increased mortality in CFTR(-/-) mice with high IL6 levels in BALFs, which was attenuated by pharmacological inhibition of cPLA2α. In addition, compared to IL6(-/-) mice, an enhanced mortality was also observed in P. aeruginosa infected IL6(+/+) mice. Since alveolar macrophages (AMs) are the primary inflammatory cytokine source in the lung, murine AMs cell line (MH-S) were used to investigate the signalling pathways involved in this process. Incubation of MH-S cells with P. aeruginosa induced IL6 production, which was mediated by MAPKs ERK/p38 and was abolished by cPLA2α inhibitors. Furthermore, among cPLA2 downstream signalling pathways, only 15-lipoxygenase (15-LOX) and cyclooxygenase-2 (COX-2) were proven to participate in this P. aeruginosa-induced IL6 expression. Based on all these observations, we conclude that cPLA2α enhances P. aeruginosa-induced animal lethality in part via IL6 induction and that MAPKs ERK/p38, 15-LOX and COX-2 signalling pathways were involved in this process.
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Affiliation(s)
- Laurent Guillemot
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France
| | - Mathieu Medina
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France
| | - Erwan Pernet
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France
| | - Dominique Leduc
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France
| | - Michel Chignard
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France
| | - Lhousseine Touqui
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France
| | - Yongzheng Wu
- Unit of Innate Defence & Inflammation, Institut Pasteur, 25 rue Dr Roux, 75015 Paris, France; INSERM U874, 25 rue Dr Roux, 75015 Paris, France.
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13
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Milla CE, Chmiel JF, Accurso FJ, VanDevanter DR, Konstan MW, Yarranton G, Geller DE. Anti-PcrV antibody in cystic fibrosis: a novel approach targeting Pseudomonas aeruginosa airway infection. Pediatr Pulmonol 2014; 49:650-8. [PMID: 24019259 PMCID: PMC4079258 DOI: 10.1002/ppul.22890] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 07/17/2013] [Indexed: 01/09/2023]
Abstract
Pseudomonas aeruginosa (Pa) airway infection is associated with increased morbidity and mortality in cystic fibrosis (CF). The type III secretion system is one of the factors responsible for the increased virulence and pro-inflammatory effects of Pa. KB001 is a PEGylated, recombinant, anti-Pseudomonas-PcrV antibody Fab' fragment that blocks the function of Pa TTSS. We studied the safety, pharmacokinetic (PK), and pharmacodynamic properties of KB001 in CF subjects with chronic Pa infection. Twenty-seven eligible CF subjects (≥12 years of age, FEV1 ≥40% of predicted, and sputum Pa density >10(5) CFU/g) received a single intravenous dose of KB001 (3 mg/kg or 10 mg/kg) or placebo. Safety, PK, Pa density, clinical outcomes, and inflammatory markers were assessed. KB001 had an acceptable safety profile and a mean serum half-life of 11.9 days. All subjects had Pa TTSS expression in sputum. There were no significant differences between KB001 and placebo for changes in Pa density, symptoms, or spirometry after a single dose. However, compared to baseline, at Day 28 there was a trend towards a dose-dependent reduction in sputum myeloperoxidase, IL-1, and IL-8, and there were significant overall differences in change in sputum neutrophil elastase and neutrophil counts favoring the KB001 10 mg/kg group versus placebo (-0.61 log(10) and -0.63 log(10) , respectively; P < 0.05). These results support targeting Pa TTSS with KB001 as a nonantibiotic strategy to reduce airway inflammation and damage in CF patients with chronic Pa infection. Repeat-dosing studies are necessary to evaluate the durability of the anti-inflammatory effects and how that may translate into clinical benefit. (NCT00638365).
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Affiliation(s)
- Carlos E Milla
- Center for Excellence in Pulmonary Biology, Stanford University, 770 Welch Road, Suite 350, Palo Alto, CA 94304.
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Faure E, Mear JB, Faure K, Normand S, Couturier-Maillard A, Grandjean T, Balloy V, Ryffel B, Dessein R, Chignard M, Uyttenhove C, Guery B, Gosset P, Chamaillard M, Kipnis E. Pseudomonas aeruginosa type-3 secretion system dampens host defense by exploiting the NLRC4-coupled inflammasome. Am J Respir Crit Care Med 2014; 189:799-811. [PMID: 24555512 DOI: 10.1164/rccm.201307-1358oc] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
RATIONALE Pseudomonas aeruginosa, a major problem pathogen responsible for severe infections in critically ill patients, triggers, through a functional type-3 secretion system (T3SS), the activation of an intracellular cytosolic sensor of innate immunity, NLRC4. Although the NLRC4-inflammasome-dependent response contributes to increased clearance of intracellular pathogens, it seems that NLRC4 inflammasome activation decreases the clearance of P. aeruginosa, a mainly extracellular pathogen. OBJECTIVES We sought to determine the underlying mechanisms of this effect of the activation of NLRC4 by P. aeruginosa. METHODS We established acute lung injury in wild-type and Nlrc4(-/-) mice using sublethal intranasal inocula of P. aeruginosa strain CHA expressing or not a functional T3SS. We studied 96-hour survival, lung injury, bacterial clearance from the lungs, cytokine secretion in bronchoalveolar lavage, lung antimicrobial peptide expression by quantitative polymerase chain reaction, and flow cytometry analysis of lung cells. MEASUREMENTS AND MAIN RESULTS Nlrc4(-/-) mice showed enhanced bacterial clearance and decreased lung injury contributing to increased survival against extracellular P. aeruginosa strain expressing a functional T3SS. The mechanism involved decreased NLRC4-inflammasome-driven IL-18 secretion attenuating lung injury caused by excessive neutrophil recruitment. Additionally, in the lungs of Nlrc4(-/-) mice secretion of IL-17 by innate immune cells was increased and responsible for increased expression of lung epithelial antimicrobial peptides. Furthermore, IL-18 secretion was found to repress IL-17 and IL-17-driven lung antimicrobial peptide expression. CONCLUSIONS We report a new role of the T3SS apparatus itself, independently of exotoxin translocation. Through NLRC4 inflammasome activation, the T3SS promotes IL-18 secretion, which dampens a beneficial IL-17-mediated antimicrobial host response.
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Affiliation(s)
- Emmanuel Faure
- 1 Pseudomonas aeruginosa Host-Pathogen Translational Research Group, Université Droit et Santé de Lille, Lille, France
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15
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Sall KM, Casabona MG, Bordi C, Huber P, de Bentzmann S, Attrée I, Elsen S. A gacS deletion in Pseudomonas aeruginosa cystic fibrosis isolate CHA shapes its virulence. PLoS One 2014; 9:e95936. [PMID: 24780952 PMCID: PMC4004566 DOI: 10.1371/journal.pone.0095936] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/30/2014] [Indexed: 11/21/2022] Open
Abstract
Pseudomonas aeruginosa, a human opportunistic pathogen, is capable of provoking acute and chronic infections that are associated with defined sets of virulence factors. During chronic infections, the bacterium accumulates mutations that silence some and activate other genes. Here we show that the cystic fibrosis isolate CHA exhibits a unique virulence phenotype featuring a mucoid morphology, an active Type III Secretion System (T3SS, hallmark of acute infections), and no Type VI Secretion System (H1-T6SS). This virulence profile is due to a 426 bp deletion in the 3′ end of the gacS gene encoding an essential regulatory protein. The absence of GacS disturbs the Gac/Rsm pathway leading to depletion of the small regulatory RNAs RsmY/RsmZ and, in consequence, to expression of T3SS, while switching off the expression of H1-T6SS and Pel polysaccharides. The CHA isolate also exhibits full ability to swim and twitch, due to active flagellum and Type IVa pili. Thus, unlike the classical scheme of balance between virulence factors, clinical strains may adapt to a local niche by expressing both alginate exopolysaccharide, a hallmark of membrane stress that protects from antibiotic action, host defences and phagocytosis, and efficient T3S machinery that is considered as an aggressive virulence factor.
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Affiliation(s)
- Khady Mayebine Sall
- INSERM, UMR-S 1036, Biology of Cancer and Infection, Grenoble, France
- CNRS, ERL 5261, Bacterial Pathogenesis and Cellular Responses, Grenoble, France
- UJF-Grenoble 1, Grenoble, France
- CEA, DSV/iRTSV, Grenoble, France
| | - Maria Guillermina Casabona
- INSERM, UMR-S 1036, Biology of Cancer and Infection, Grenoble, France
- CNRS, ERL 5261, Bacterial Pathogenesis and Cellular Responses, Grenoble, France
- UJF-Grenoble 1, Grenoble, France
- CEA, DSV/iRTSV, Grenoble, France
| | - Christophe Bordi
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, UMR 7255 CNRS - Aix Marseille University, Marseille, France
| | - Philippe Huber
- INSERM, UMR-S 1036, Biology of Cancer and Infection, Grenoble, France
- CNRS, ERL 5261, Bacterial Pathogenesis and Cellular Responses, Grenoble, France
- UJF-Grenoble 1, Grenoble, France
- CEA, DSV/iRTSV, Grenoble, France
| | - Sophie de Bentzmann
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, UMR 7255 CNRS - Aix Marseille University, Marseille, France
| | - Ina Attrée
- INSERM, UMR-S 1036, Biology of Cancer and Infection, Grenoble, France
- CNRS, ERL 5261, Bacterial Pathogenesis and Cellular Responses, Grenoble, France
- UJF-Grenoble 1, Grenoble, France
- CEA, DSV/iRTSV, Grenoble, France
| | - Sylvie Elsen
- INSERM, UMR-S 1036, Biology of Cancer and Infection, Grenoble, France
- CNRS, ERL 5261, Bacterial Pathogenesis and Cellular Responses, Grenoble, France
- UJF-Grenoble 1, Grenoble, France
- CEA, DSV/iRTSV, Grenoble, France
- * E-mail:
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16
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Audia JP, Lindsey AS, Housley NA, Ochoa CR, Zhou C, Toba M, Oka M, Annamdevula NS, Fitzgerald MS, Frank DW, Alvarez DF. In the absence of effector proteins, the Pseudomonas aeruginosa type three secretion system needle tip complex contributes to lung injury and systemic inflammatory responses. PLoS One 2013; 8:e81792. [PMID: 24312357 PMCID: PMC3842252 DOI: 10.1371/journal.pone.0081792] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/16/2013] [Indexed: 01/06/2023] Open
Abstract
Herein we describe a pathogenic role for the Pseudomonas aeruginosa type three secretion system (T3SS) needle tip complex protein, PcrV, in causing lung endothelial injury. We first established a model in which P. aeruginosa wild type strain PA103 caused pneumonia-induced sepsis and distal organ dysfunction. Interestingly, a PA103 derivative strain lacking its two known secreted effectors, ExoU and ExoT [denoted PA103 (ΔU/ΔT)], also caused sepsis and modest distal organ injury whereas an isogenic PA103 strain lacking the T3SS needle tip complex assembly protein [denoted PA103 (ΔPcrV)] did not. PA103 (ΔU/ΔT) infection caused neutrophil influx into the lung parenchyma, lung endothelial injury, and distal organ injury (reminiscent of sepsis). In contrast, PA103 (ΔPcrV) infection caused nominal neutrophil infiltration and lung endothelial injury, but no distal organ injury. We further examined pathogenic mechanisms of the T3SS needle tip complex using cultured rat pulmonary microvascular endothelial cells (PMVECs) and revealed a two-phase, temporal nature of infection. At 5-hours post-inoculation (early phase infection), PA103 (ΔU/ΔT) elicited PMVEC barrier disruption via perturbation of the actin cytoskeleton and did so in a cell death-independent manner. Conversely, PA103 (ΔPcrV) infection did not elicit early phase PMVEC barrier disruption. At 24-hours post-inoculation (late phase infection), PA103 (ΔU/ΔT) induced PMVEC damage and death that displayed an apoptotic component. Although PA103 (ΔPcrV) infection induced late phase PMVEC damage and death, it did so to an attenuated extent. The PA103 (ΔU/ΔT) and PA103 (ΔPcrV) mutants grew at similar rates and were able to adhere equally to PMVECs post-inoculation indicating that the observed differences in damage and barrier disruption are likely attributable to T3SS needle tip complex-mediated pathogenic differences post host cell attachment. Together, these infection data suggest that the T3SS needle tip complex and/or another undefined secreted effector(s) are important determinants of P. aeruginosa pneumonia-induced lung endothelial barrier disruption.
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Affiliation(s)
- Jonathon P. Audia
- Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
- * E-mail: (JPA); (DFA)
| | - Ashley S. Lindsey
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Nicole A. Housley
- Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Courtney R. Ochoa
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Chun Zhou
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Michie Toba
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Masahiko Oka
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Naga S. Annamdevula
- Department of Chemical and Biomolecular Engineering, University of South Alabama, Mobile, Alabama, United States of America
| | - Meshann S. Fitzgerald
- Department of Internal Medicine, University of South Alabama, Mobile, Alabama, United States of America
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Dara W. Frank
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Diego F. Alvarez
- Department of Internal Medicine, University of South Alabama, Mobile, Alabama, United States of America
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
- * E-mail: (JPA); (DFA)
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17
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De Soyza A, Hall AJ, Mahenthiralingam E, Drevinek P, Kaca W, Drulis-Kawa Z, Stoitsova SR, Toth V, Coenye T, Zlosnik JEA, Burns JL, Sá-Correia I, De Vos D, Pirnay JP, Kidd TJ, Reid D, Manos J, Klockgether J, Wiehlmann L, Tümmler B, McClean S, Winstanley C. Developing an international Pseudomonas aeruginosa reference panel. Microbiologyopen 2013; 2:1010-23. [PMID: 24214409 PMCID: PMC3892346 DOI: 10.1002/mbo3.141] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 09/27/2013] [Accepted: 10/07/2013] [Indexed: 01/22/2023] Open
Abstract
Pseudomonas aeruginosa is a major opportunistic pathogen in cystic fibrosis (CF) patients and causes a wide range of infections among other susceptible populations. Its inherent resistance to many antimicrobials also makes it difficult to treat infections with this pathogen. Recent evidence has highlighted the diversity of this species, yet despite this, the majority of studies on virulence and pathogenesis focus on a small number of strains. There is a pressing need for a P. aeruginosa reference panel to harmonize and coordinate the collective efforts of the P. aeruginosa research community. We have collated a panel of 43 P. aeruginosa strains that reflects the organism's diversity. In addition to the commonly studied clones, this panel includes transmissible strains, sequential CF isolates, strains with specific virulence characteristics, and strains that represent serotype, genotype or geographic diversity. This focussed panel of P. aeruginosa isolates will help accelerate and consolidate the discovery of virulence determinants, improve our understanding of the pathogenesis of infections caused by this pathogen, and provide the community with a valuable resource for the testing of novel therapeutic agents.
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Affiliation(s)
- Anthony De Soyza
- Institute of Cellular Medicine, Newcastle University, Newcastle, U.K
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18
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Galle M, Carpentier I, Beyaert R. Structure and function of the Type III secretion system of Pseudomonas aeruginosa. Curr Protein Pept Sci 2012; 13:831-42. [PMID: 23305368 PMCID: PMC3706959 DOI: 10.2174/138920312804871210] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 07/19/2012] [Accepted: 07/25/2012] [Indexed: 02/08/2023]
Abstract
Pseudomonas aeruginosa is a dangerous pathogen particularly because it harbors multiple virulence factors. It causes several types of infection, including dermatitis, endocarditis, and infections of the urinary tract, eye, ear, bone, joints and, of particular interest, the respiratory tract. Patients with cystic fibrosis, who are extremely susceptible to Pseudomonas infections, have a bad prognosis and high mortality. An important virulence factor of P. aeruginosa, shared with many other gram-negative bacteria, is the type III secretion system, a hollow molecular needle that transfers effector toxins directly from the bacterium into the host cell cytosol. This complex macromolecular machine works in a highly regulated manner and can manipulate the host cell in many different ways. Here we review the current knowledge of the structure of the P. aeruginosa T3SS, as well as its function and recognition by the immune system. Furthermore, we describe recent progress in the development and use of therapeutic agents targeting the T3SS.
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Affiliation(s)
- Marlies Galle
- Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium; the
- Department for Molecular Biomedical Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Technologiepark 927, B-9052 Ghent, Belgium
| | - Isabelle Carpentier
- Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium; the
- Department for Molecular Biomedical Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Technologiepark 927, B-9052 Ghent, Belgium
| | - Rudi Beyaert
- Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium; the
- Department for Molecular Biomedical Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Technologiepark 927, B-9052 Ghent, Belgium
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19
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The Pseudomonas aeruginosa type III secretion system has an exotoxin S/T/Y independent pathogenic role during acute lung infection. PLoS One 2012; 7:e41547. [PMID: 22844497 PMCID: PMC3402384 DOI: 10.1371/journal.pone.0041547] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Accepted: 06/27/2012] [Indexed: 12/21/2022] Open
Abstract
The type III secretion system (T3SS) is a complex nanomachine of many pathogenic Gram-negative bacteria. It forms a proteinaceous channel that is inserted into the host eukaryotic cell membrane for injection of bacterial proteins that manipulate host cell signaling. However, few studies have focused on the effector-independent functions of the T3SS. Using a murine model of acute lung infection with Pseudomonas aeruginosa, an important human opportunistic pathogen, we compared the pathogenicity of mutant bacteria that lack all of the known effector toxins ( ΔSTY), with mutant bacteria that also lack the major translocator protein PopB (ΔSTY/ΔPopB) and so cannot form a functional T3SS channel in the host cell membrane. Mortality was higher among mice challenged with ΔSTY compared to mice challenged with ΔSTY/ΔPopB mutant bacteria. In addition, mice infected with ΔSTY showed decreased bacterial clearance from the lungs compared to those infected with ΔSTY/ΔPopB. Infection was in both cases associated with substantial killing of lung infiltrating macrophages. However, macrophages from ΔSTY-infected mice died by pro-inflammatory necrosis characterized by membrane permeabilization and caspase-1 mediated IL-1β production, whereas macrophages from ΔSTY/ΔPopB infected mice died by apoptosis, which is characterized by annexin V positive staining of the cell membrane and caspase-3 activation. This was confirmed in macrophages infected in vitro. These results demonstrate a T3SS effector toxin independent role for the T3SS, in particular the T3SS translocator protein PopB, in the pathogenicity of P. aeruginosa during acute lung infection.
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20
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Tramper-Stranders G, van der Ent C, Molin S, Yang L, Hansen S, Rau M, Ciofu O, Johansen H, Wolfs T. Initial Pseudomonas aeruginosa infection in patients with cystic fibrosis: characteristics of eradicated and persistent isolates. Clin Microbiol Infect 2012; 18:567-74. [DOI: 10.1111/j.1469-0691.2011.03627.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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22
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Affiliation(s)
- Diego Romero
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | - Matthew F. Traxler
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | | | - Roberto Kolter
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
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23
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Le Berre R, Nguyen S, Nowak E, Kipnis E, Pierre M, Quenee L, Ader F, Lancel S, Courcol R, Guery BP, Faure K. Relative contribution of three main virulence factors in Pseudomonas aeruginosa pneumonia*. Crit Care Med 2011; 39:2113-20. [DOI: 10.1097/ccm.0b013e31821e899f] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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24
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The sensor kinase KinB regulates virulence in acute Pseudomonas aeruginosa infection. J Bacteriol 2011; 193:2989-99. [PMID: 21515773 DOI: 10.1128/jb.01546-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two-component sensors are widely used by bacteria to sense and respond to the environment. Pseudomonas aeruginosa has one of the largest sets of two-component sensors known in bacteria, which likely contributes to its unique ability to adapt to multiple environments, including the human host. Several of these two-component sensors, such as GacS and RetS, have been shown to play roles in virulence in rodent infection models. However, the role and function of the majority of these two-component sensors remain unknown. Danio rerio is a recently characterized model host for pathogenesis-related studies that is amenable to higher-throughput analysis than mammalian models. Using zebrafish embryos as a model host, we have systematically tested the role of 60 two-component sensors and identified 6 sensors that are required for P. aeruginosa virulence. We found that KinB is required for acute infection in zebrafish embryos and regulates a number of virulence-associated phenotypes, including quorum sensing, biofilm formation, and motility. Its regulation of these phenotypes is independent of its kinase activity and its known response regulator AlgB, suggesting that it does not fit the canonical two-component sensor-response regulator model.
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25
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Development of two animal models to study the function of Vibrio parahaemolyticus type III secretion systems. Infect Immun 2010; 78:4551-9. [PMID: 20823199 DOI: 10.1128/iai.00461-10] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vibrio parahaemolyticus is an emerging food- and waterborne pathogen that encodes two type III secretion systems (T3SSs). Previous studies have linked type III secretion system 1 (T3SS1) to cytotoxicity and T3SS2 to intestinal fluid accumulation, but animal challenge models needed to study these phenomena are limited. In this study we evaluated the roles of the T3SSs during infection using two novel animal models: a model in which piglets were inoculated orogastrically and a model in which mice were inoculated in their lungs (intrapulmonarily). The bacterial strains employed in this study had equivalent growth rates and beta-hemolytic activity based on in vitro assays. Inoculation of 48-h-old conventional piglets with 10(11) CFU of the wild-type strain (NY-4) or T3SS1 deletion mutant strains resulted in acute, self-limiting diarrhea, whereas inoculation with a T3SS2 deletion mutant strain failed to produce any clinical symptoms. Intrapulmonary inoculation of C57BL/6 mice with the wild-type strain and T3SS2 deletion mutant strains (5 × 10(5) CFU) induced mortality or a moribund state within 12 h (80 to 100% mortality), whereas inoculation with a T3SS1 deletion mutant or a T3SS1 T3SS2 double deletion mutant produced no mortality. Bacteria were recovered from multiple organs regardless of the strain used in the mouse model, indicating that the mice were capable of clearing the lung infection in the absence of a functional T3SS1. Because all strains had a similar beta-hemolysin phenotype, we surmise that thermostable direct hemolysin (TDH) plays a limited role in these models. The two models introduced herein produce robust results and provide a means to determine how different T3SS1 and T3SS2 effector proteins contribute to pathogenesis of V. parahaemolyticus infection.
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26
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Dubin PJ, Kolls JK. Pseudomonas aeruginosa and the host pulmonary immune response. Expert Rev Respir Med 2010; 1:121-37. [PMID: 20477272 DOI: 10.1586/17476348.1.1.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pseudomonas aeruginosa is a highly adaptable, opportunistic pathogen that is commonly found in the environment. It can infect a number of sites in the body and disseminate. It can cause both acute and chronic pulmonary infection and the acuity of infection and accompanying inflammatory phenotype is determined, for the most part, by the host. Although P. aeruginosa has been a successful opportunist in the context of a number of different disease states, it has been best studied in the context of cystic fibrosis (CF). The adaptability of P. aeruginosa has enabled it to adjust quickly to the CF airway, transitioning from initial colonization to chronic infection. The organism quickly expresses virulence factors that allow it to circumvent some elements of the host immune response and, even more importantly, quickly develops antimicrobial resistance. In the case of CF, chronic infection resulting in progressive lung damage, coupled with antimicrobial resistance, becomes an increasingly important issue as individuals with CF live longer. It is for these reasons that both organism- and host-targeted immunotherapies are being increasingly explored.
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Affiliation(s)
- Patricia J Dubin
- Children's Hospital of Pittsburgh, Suite 3765, 3705 Fifth Avenue, Pittsburgh, PA 15213, USA.
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Rottier BL, van Erp CJ, Sluyter TS, Heijerman HG, Frijlink HW, de Boer AH. Changes in Performance of the Pari eFlow® Rapid and Pari LC Plus™ during 6 Months Use by CF Patients. J Aerosol Med Pulm Drug Deliv 2009; 22:263-9. [DOI: 10.1089/jamp.2008.0712] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Bart L. Rottier
- Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Cyril J.P. van Erp
- Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, The Netherlands
| | | | | | - Henderik W. Frijlink
- Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, The Netherlands
| | - Anne H. de Boer
- Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, The Netherlands
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Abstract
The Gram-negative bacterium Pseudomonas aeruginosa uses a complex type III secretion apparatus to inject effector proteins into host cells. The configuration of this secretion machinery, the activities of the proteins that are injected by it and the consequences of this process for infection are now being elucidated. This Review summarizes our current knowledge of P. aeruginosa type III secretion, including the secretion and translocation machinery, the regulation of this machinery, and the associated chaperones and effector proteins. The features of this interesting secretion system have important implications for the pathogenesis of P. aeruginosa infections and for other type III secretion systems.
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Affiliation(s)
- Alan R Hauser
- Departments of MicrobiologyImmunology and Medicine, Northwestern University, Chicago, Illinois 60611, USA.
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29
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Role of LecA and LecB lectins in Pseudomonas aeruginosa-induced lung injury and effect of carbohydrate ligands. Infect Immun 2009; 77:2065-75. [PMID: 19237519 DOI: 10.1128/iai.01204-08] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is a frequently encountered pathogen that is involved in acute and chronic lung infections. Lectin-mediated bacterium-cell recognition and adhesion are critical steps in initiating P. aeruginosa pathogenesis. This study was designed to evaluate the contributions of LecA and LecB to the pathogenesis of P. aeruginosa-mediated acute lung injury. Using an in vitro model with A549 cells and an experimental in vivo murine model of acute lung injury, we compared the parental strain to lecA and lecB mutants. The effects of both LecA- and Lec B-specific lectin-inhibiting carbohydrates (alpha-methyl-galactoside and alpha-methyl-fucoside, respectively) were evaluated. In vitro, the parental strain was associated with increased cytotoxicity and adhesion on A549 cells compared to the lecA and lecB mutants. In vivo, the P. aeruginosa-induced increase in alveolar barrier permeability was reduced with both mutants. The bacterial burden and dissemination were decreased for both mutants compared with the parental strain. Coadministration of specific lectin inhibitors markedly reduced lung injury and mortality. Our results demonstrate that there is a relationship between lectins and the pathogenicity of P. aeruginosa. Inhibition of the lectins by specific carbohydrates may provide new therapeutic perspectives.
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Effects of antibiotics on quorum sensing in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2008; 52:3648-63. [PMID: 18644954 DOI: 10.1128/aac.01230-07] [Citation(s) in RCA: 256] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
During infection, Pseudomonas aeruginosa employs bacterial communication (quorum sensing [QS]) to coordinate the expression of tissue-damaging factors. QS-controlled gene expression plays a pivotal role in the virulence of P. aeruginosa, and QS-deficient mutants cause less severe infections in animal infection models. Treatment of cystic fibrosis (CF) patients chronically infected with P. aeruginosa with the macrolide antibiotic azithromycin (AZM) has been demonstrated to improve the clinical outcome. Several studies indicate that AZM may accomplish its beneficial action in CF patients by impeding QS, thereby reducing the pathogenicity of P. aeruginosa. This led us to investigate whether QS inhibition is a common feature of antibiotics. We present the results of a screening of 12 antibiotics for their QS-inhibitory activities using a previously described QS inhibitor selector 1 strain. Three of the antibiotics tested, AZM, ceftazidime (CFT), and ciprofloxacin (CPR), were very active in the assay and were further examined for their effects on QS-regulated virulence factor production in P. aeruginosa. The effects of the three antibiotics administered at subinhibitory concentrations were investigated by use of DNA microarrays. Consistent results from the virulence factor assays, reverse transcription-PCR, and the DNA microarrays support the finding that AZM, CFT, and CPR decrease the expression of a range of QS-regulated virulence factors. The data suggest that the underlying mechanism may be mediated by changes in membrane permeability, thereby influencing the flux of N-3-oxo-dodecanoyl-L-homoserine lactone.
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Hafiane A, Ravaoarinoro M. [Various typing methods of Pseudomonas aeruginosa strains isolated from cystic fibrosis patients]. Med Mal Infect 2008; 38:238-47. [PMID: 18394837 DOI: 10.1016/j.medmal.2008.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 11/09/2007] [Accepted: 02/12/2008] [Indexed: 11/26/2022]
Abstract
Typing methods are essential to understand the epidemiology of bacterial infections. Strain typing is important for the detection of sources or routes of infections, identification between endemic and epidemic strains and prevention of transmission between patients. Some Pseudomonas aeruginosa cystic-fibrosis strains could not be typed with conventional typing methods. Due to the diverse phenotypic nature of P. aeruginosa, phenotyping methods are not discriminatory enough to identify strains belonging to the same genotype. Thus, molecular typing methods are required. These methods should be applied when data from phenotypic typing analysis becomes ambiguous, such as in cystic fibrosis. Molecular typing methods, developed over the past decade, are highly discriminatory in capacity and reproducibility. However, they are more likely applied in specialized laboratories since they are expensive and increase the workload. A reliable and low-cost typing system is required for better defining the epidemiology of this pathogen and designing more rational policies of infection control. Comparison between typing methods will pinpoint the limits and effectiveness of each method and will improve in turn the choice of a nonspecialized laboratory in terms of simplicity, time and cost.
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Affiliation(s)
- A Hafiane
- Department of Medical microbiology and Infectiology, CHUM Hôtel-Dieu, Montréal, Québec, Canada
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Vaccination against Pseudomonas aeruginosa pneumonia in immunocompromised mice. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 15:367-75. [PMID: 18094113 DOI: 10.1128/cvi.00419-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Immunocompromised patients are highly susceptible to infection with Pseudomonas aeruginosa. Our laboratory previously showed that intranasal administration of an attenuated Salmonella strain expressing the P. aeruginosa lipopolysaccharide O antigen was effective in clearing bacteria and preventing mortality in wild-type mice after intranasal challenge. We were interested in investigating the efficacy of this vaccine strategy in immunocompromised mice. Mice rendered leukopenic or neutropenic by intraperitoneal treatment with cyclophosphamide (Cy) or RB6-8C5 antibody, respectively, were more susceptible to P. aeruginosa pneumonia than their nontreated counterparts, demonstrating 50% lethal doses several logs lower than that in wild-type mice. This hypersusceptiblity was also associated with bacterial dissemination to the liver and spleen and increased lung permeability in Cy mice. Vaccination of the mice prior to treatment resulted in better survival and lower bacterial loads compared to vector-immunized mice. Although the treatments had no effect on antibody titers, this level of protection was still lower than that seen in untreated vaccinated mice. Administration of antibodies directly to the site of infection at the time of bacterial delivery prolonged survival and lowered bacterial loads in the immunocompromised mice. These results demonstrate the importance of white blood cells while still suggesting a critical role for antibodies in protection against P. aeruginosa infection.
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Evans DJ, McNamara NA, Fleiszig SMJ. Life at the front: dissecting bacterial-host interactions at the ocular surface. Ocul Surf 2007; 5:213-27. [PMID: 17660895 DOI: 10.1016/s1542-0124(12)70612-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ocular surface usually looks quiet, presenting a general impression of biological inactivity. Yet, the ability of the cornea to maintain health while continually exposed to environmental insults, and in the relative absence of immune strategies afforded by other body sites, reflects its complexity. Because it is critical for transparency and, therefore, our survival, the fine structure of the cornea has likely provided the driving force for the evolution of what appears to be a truly remarkable system. While several molecules are now known to participate, we are only beginning to obtain the knowledge to fully explain the mechanisms involved in corneal resistance to infection. Full explanation will require a better understanding of the interplay between microbes and various components of the ocular surface, and of the critical factors determining health as the usual outcome. To understand infectious disease, we need to consider how the scenario changes in conditions associated with susceptibility. What we learn in the process could yield a wealth of potential therapies for a wide variety of diseases of the eye and of other sites.
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Affiliation(s)
- David J Evans
- School of Optometry, University of California, Berkeley, California 94720-2020, USA
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Pierre M, Husson MO, Le Berre R, Desseyn JL, Galabert C, Béghin L, Beermann C, Dagenais A, Berthiaume Y, Cardinaud B, Barbry P, Gottrand F, Guery BP. Omega-3 polyunsaturated fatty acids improve host response in chronicPseudomonas aeruginosalung infection in mice. Am J Physiol Lung Cell Mol Physiol 2007; 292:L1422-31. [PMID: 17322280 DOI: 10.1152/ajplung.00337.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Pseudomonas aeruginosa is a gram-negative bacilli frequently encountered in human pathology. This pathogen is involved in a large number of nosocomial infections and chronic diseases. Herein we investigated the effects of polyunsaturated fatty acids (PUFA) in chronic Pseudomonas aeruginosa lung infection. C57BL/6 mice were fed for 5 wk with specifically designed diets with high contents in either omega-3 (ω-3) or ω-6 PUFA and compared to a control diet. P. aeruginosa included in agarose beads was then instilled intratracheally, and the animals were studied for 7 days. On the 4th day, the mice fed with the ω-3 diet had a higher lean body mass gain and a lower ω-6:ω-3 ratio of fatty acids extracted from the lung tissue compared with the other groups ( P < 0.05). The ω-3 group had the lowest mortality. Distal alveolar fluid clearance (DAFC) as well as the inflammatory response and the cellular recruitment were higher in the ω-3 group on the 4th day. The effect on DAFC was independent of α-epithelial Na+channels (α-ENaC), β-ENaC, and α1-Na-K-ATPase mRNA expressions, which were not altered by the different diets. In conclusion, a diet enriched in ω-3 PUFA can change lung membrane composition and improve survival in chronic pneumonia. This effect on survival is probably multifactorial involving the increased DAFC capacity as well as the optimization of the initial inflammatory response. This work suggests that a better control of the ω-6/ω-3 PUFA balance may represent an interesting target in the prevention and/or control of P. aeruginosa infection in patients.
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Affiliation(s)
- Maud Pierre
- Faculté de Médecine, Hôpital Jeanne de Flandre, Université de Lille and CHRU de Lille, France
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Marra A. Targeting virulence for antibacterial chemotherapy: identifying and characterising virulence factors for lead discovery. Drugs R D 2006; 7:1-16. [PMID: 16620133 DOI: 10.2165/00126839-200607010-00001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The antibacterial drug discovery industry is fast losing participants; at the same time it is facing the challenge of developing new antibiotics that are effective against frequently occurring and multiply resistant organisms. One intriguing approach is to target bacterial virulence, and the last decade or so has seen a focus on bacterial pathogenesis along with the development of reagents and strategies that could make this possible. Several processes utilised by a range of bacteria to cause infection may be conserved enough to make attractive targets; indeed it is known that mammalian cells can affect bacterial gene expression and vice versa. Interesting targets involving virulence include type III secretion systems, two-component signal transduction systems, quorum sensing, and biofilm formation. In order to better understand these systems and strategies, investigators have developed novel strategies of their own, involving negative selections, surrogate models of infection, and screens for gene induction and antigenicity. Inhibitors of such targets would be unlikely to adversely affect patients, be cross-resistant to existing therapies, or cause resistance themselves. It might be the case that virulence target-based therapies would not be powerful enough to clear an existing infection alone, but if they are instead considered as adjunct therapy to existing antibiotics, or potentiators of the host immune response, they may show efficacy in a non-traditional way.
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Zolfaghar I, Evans DJ, Ronaghi R, Fleiszig SMJ. Type III secretion-dependent modulation of innate immunity as one of multiple factors regulated by Pseudomonas aeruginosa RetS. Infect Immun 2006; 74:3880-9. [PMID: 16790760 PMCID: PMC1489705 DOI: 10.1128/iai.01891-05] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutation of retS (rtsM) of Pseudomonas aeruginosa strain PA103 reduces its virulence in both ocular and respiratory murine models of infection. In vitro, retS mutants exhibit loss of the ExsA-regulated type III secretion system (TTSS), reduced twitching motility, and a decrease in association with, invasion of, and survival within corneal epithelial cells. In addition, transcription of multiple other virulence genes is positively and negatively affected by retS mutation. Since our published data show that ExoU and ExoT, the two TTSS effectors encoded by strain PA103, each confer virulence in this corneal model, we hypothesized that loss of virulence of retS mutants follows loss of type III secretion. Corneal pathology, bacterial colonization, and phagocyte infiltration were compared for wild-type PA103, retS mutants, and various TTSS mutants after infection with approximately 10(6) CFU bacteria. Results showed that either a retS or an exsA (TTSS) mutation delayed disease progression, as illustrated by reduced severity scores and colonization levels during the first 48 h postinfection. Surprisingly, retS mutant infections then became more severe than those involving exsA mutants. By day 7, colonization levels of retS mutants even surpassed those of wild-type bacteria (more than twofold, P = 0.028). Although retS mutants caused more severe opacification of central corneas than both the wild type and the exsA mutants, neither mutant caused the peripheral ring opacity commonly associated with wild-type infection, suggesting that the TTSS was involved. Histological experiments with retS and various TTSS mutants showed that ring opacification required ExoU but not ExoT and that it consisted of dense polymorphonuclear phagocyte infiltration at the corneal periphery and the absence of any cell type in the central cornea. These data suggest that these P. aeruginosa TTSS effectors have different effects on innate immunity and that RetS influences virulence beyond its effects on the TTSS.
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Melstrom KA, Smith JW, Gamelli RL, Shankar R. New perspectives for a new century: implications of pathogen responses for the future of antimicrobial therapy. J Burn Care Res 2006; 27:251-64. [PMID: 16679890 DOI: 10.1097/01.bcr.0000216291.68192.54] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although the discovery of new classes of antibiotics has lagged behind in the last three decades, the incidence of life-threatening nosocomial infections that are resistant to multiple antibacterial agents has increased steadily. Recent advances in bacterial pathogenicity through the identification of a number of virulence factors and the bacterial genetics behind it have opened the way to a clearer understanding of the pathogen-host relationship. Bacteria communicate with each other through specific signaling chemicals to act as a community rather than individual cells to achieve a critical density or a "quorum." Establishment of quorum is the initiating signal for turning on a variety of virulence factors essential for the pathogenicity and dissemination of pathogens through the host. Pathogenic bacteria use a variety of biochemical mediators, collectively called "virulence factors," to invade and attack host tissues and to avoid detection and elimination by the host immune system. Delineating the specific responses the host immune system elicits in response to specific virulence factors and quorum-sensing molecules is essential to the development of new diagnostic methods for early detection of an infection and the prognosis to a given antibacterial therapy. Identification of inhibitors of virulence factors will represent new antimicrobial therapeutic modalities, and this can be used synergistically with current antibiotic therapy because they act through independent prokaryotic pathways to inhibit bacterial growth and survival.
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Affiliation(s)
- Kurt A Melstrom
- Department of Surgery and Burn & Shock Trauma Institute, Loyola University Medical Center, Maywood, Illinois 60153, USA
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Filopon D, Mérieau A, Bernot G, Comet JP, LeBerre R, Guery B, Polack B, Guespin-Michel J. Epigenetic acquisition of inducibility of type III cytotoxicity in P. aeruginosa. BMC Bioinformatics 2006; 7:272. [PMID: 16734902 PMCID: PMC1488876 DOI: 10.1186/1471-2105-7-272] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Accepted: 05/30/2006] [Indexed: 11/06/2022] Open
Abstract
Background Pseudomonas aeruginosa, an opportunistic pathogen, is often encountered in chronic lung diseases such as cystic fibrosis or chronic obstructive pneumonia, as well as acute settings like mechanical ventilation acquired pneumonia or neutropenic patients. It is a major cause of mortality and morbidity in these diseases. In lungs, P. aeruginosa settles in a biofilm mode of growth with the secretion of exopolysaccharides in which it is encapsulated, enhancing its antibiotic resistance and contributing to the respiratory deficiency of patients. However, bacteria must first multiply to a high density and display a cytotoxic phenotype to avoid the host's defences. A virulence determinant implicated in this step of infection is the type III secretion system (TTSS), allowing toxin injection directly into host cells. At the beginning of the infection, most strains isolated from patients' lungs possess an inducible TTSS allowing toxins injection or secretion upon in vivo or in vitro activation signals. As the infection persists most of the bacteria permanently loose this capacity, although no mutations have been evidenced. We name "non inducible" this phenotype. As suggested by the presence of a positive feedback circuit in the regulatory network controlling TTSS expression, it may be due to an epigenetic switch allowing heritable phenotypic modifications without genotype's mutations. Results Using the generalised logical method, we designed a minimal model of the TTSS regulatory network that could support the epigenetic hypothesis, and studied its dynamics which helped to define a discriminating experimental scenario sufficient to validate the epigenetic hypothesis. A mathematical framework based on formal methods from computer science allowed a rigorous validation and certification of parameters of this model leading to epigenetic behaviour. Then, we demonstrated that a non inducible strain of P. aeruginosa can stably acquire the capacity to be induced by calcium depletion for the TTSS after a short pulse of a regulatory protein. Finally, the increased cytotoxicity of a strain after this epigenetic switch was demonstrated in vivo in an acute pulmonary infection model. Conclusion These results may offer new perspectives for therapeutic strategies to prevent lethal infections by P. aeruginosa by reverting the epigenetic inducibility of type III cytotoxicity.
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Affiliation(s)
- Didier Filopon
- GREPI EA 2938 CHU de Grenoble, BP 217, 38043 Grenoble cedex 9, France
| | - Annabelle Mérieau
- Laboratoire de microbiologie du froid, EA 2123, Université de Rouen, F-76 821 Mt St Aignan, France
| | - Gilles Bernot
- LaMI, CNRS UMR 8042, Université d'Évry-Val-d'Essonne, Boulevard François Mitterrand, 91025 Évry, France
| | - Jean-Paul Comet
- LaMI, CNRS UMR 8042, Université d'Évry-Val-d'Essonne, Boulevard François Mitterrand, 91025 Évry, France
| | - Rozenne LeBerre
- EA 2689, Faculté de Médecine, Pole Recherche, CHRU de Lille, 1 Place de Verdun, 59045 Lille, France
| | - Benoit Guery
- EA 2689, Faculté de Médecine, Pole Recherche, CHRU de Lille, 1 Place de Verdun, 59045 Lille, France
| | - Benoit Polack
- GREPI EA 2938 CHU de Grenoble, BP 217, 38043 Grenoble cedex 9, France
| | - Janine Guespin-Michel
- Laboratoire de microbiologie du froid, EA 2123, Université de Rouen, F-76 821 Mt St Aignan, France
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Kipnis E, Sawa T, Wiener-Kronish J. Targeting mechanisms of Pseudomonas aeruginosa pathogenesis. Med Mal Infect 2006; 36:78-91. [PMID: 16427231 DOI: 10.1016/j.medmal.2005.10.007] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 10/18/2005] [Indexed: 01/08/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen responsible for ventilator-acquired pneumonia, acute lower respiratory tract infections in immunocompromised patients and chronic respiratory infections in cystic fibrosis patients. High incidence, infection severity and increasing resistance characterize P. aeruginosa infections, highlighting the need for new therapeutic options. One such option is to target the many pathogenic mechanisms conferred to P. aeruginosa by its large genome encoding many different virulence factors. This article reviews the pathogenic mechanisms and potential therapies targeting these mechanisms in P. aeruginosa respiratory infections.
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Affiliation(s)
- E Kipnis
- Department of Anesthesia and Perioperative Care, University of California San Francisco, 513 Parnassus Avenue, Room s-261, Medical Science Building, Box 0542, San Francisco, CA 94143, USA.
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