1
|
Poret AJ, Schaefers M, Merakou C, Mansour KE, Lagoudas GK, Cross AR, Goldberg JB, Kishony R, Uluer AZ, McAdam AJ, Blainey PC, Vargas SO, Lieberman TD, Priebe GP. De novo mutations mediate phenotypic switching in an opportunistic human lung pathogen. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.06.579193. [PMID: 38370793 PMCID: PMC10871308 DOI: 10.1101/2024.02.06.579193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Bacteria evolving within human hosts encounter selective tradeoffs that render mutations adaptive in one context and deleterious in another. Here, we report that the cystic fibrosis-associated pathogen Burkholderia dolosa overcomes in-human selective tradeoffs by acquiring successive point mutations that alternate phenotypes. We sequenced the whole genomes of 931 respiratory isolates from two recently infected patients and an epidemiologically-linked, chronically-infected patient. These isolates are contextualized using 112 historical genomes from the same outbreak strain. Within both newly infected patients, diverse parallel mutations that disrupt O-antigen expression quickly arose, comprising 29% and 63% of their B. dolosa communities by 3 years. The selection for loss of O-antigen starkly contrasts with our previous observation of parallel O-antigen-restoring mutations after many years of chronic infection in the historical outbreak. Experimental characterization revealed that O-antigen loss increases uptake in immune cells while decreasing competitiveness in the mouse lung. We propose that the balance of these pressures, and thus whether O-antigen expression is advantageous, depends on tissue localization and infection duration. These results suggest that mutation-driven alternation during infection may be more frequent than appreciated and is underestimated without dense temporal sampling.
Collapse
Affiliation(s)
- Alexandra J. Poret
- Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology
- Department of Biological Engineering, Massachusetts Institute of Technology
| | - Matthew Schaefers
- Department of Anesthesiology, Critical Care and Pain Medicine, Division of Critical Care Medicine, Boston Children's Hospital
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts
| | - Christina Merakou
- Department of Anesthesiology, Critical Care and Pain Medicine, Division of Critical Care Medicine, Boston Children's Hospital
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts
| | - Kathryn E. Mansour
- Department of Anesthesiology, Critical Care and Pain Medicine, Division of Critical Care Medicine, Boston Children's Hospital
| | - Georgia K. Lagoudas
- Department of Biological Engineering, Massachusetts Institute of Technology
- Broad Institute of MIT and Harvard
| | - Ashley R. Cross
- Department of Pediatrics, Division of Pulmonary, Asthma, Cystic Fibrosis, and Sleep, Emory University School of Medicine
| | - Joanna B. Goldberg
- Department of Pediatrics, Division of Pulmonary, Asthma, Cystic Fibrosis, and Sleep, Emory University School of Medicine
| | - Roy Kishony
- Faculty of Biology and Faculty of Computer Science, Technion Israel
| | - Ahmet Z. Uluer
- Department of Pediatrics, Division of Respiratory Diseases, Boston Children’s Hospital
- Adult CF Program, Brigham and Women’s Hospital
- Department of Pediatrics, Harvard Medical School
| | - Alexander J. McAdam
- Department of Laboratory Medicine, Boston Children’s Hospital
- Department of Pathology, Harvard Medical School
| | - Paul C. Blainey
- Department of Biological Engineering, Massachusetts Institute of Technology
- Broad Institute of MIT and Harvard
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology
| | - Sara O. Vargas
- Department of Pathology, Harvard Medical School
- Department of Pathology, Boston Children’s Hospital
| | - Tami D. Lieberman
- Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology
- Department of Anesthesiology, Critical Care and Pain Medicine, Division of Critical Care Medicine, Boston Children's Hospital
| | - Gregory P. Priebe
- Department of Anesthesiology, Critical Care and Pain Medicine, Division of Critical Care Medicine, Boston Children's Hospital
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts
- Broad Institute of MIT and Harvard
- Department of Pediatrics, Division of Infectious Diseases, Boston Children’s Hospital
| |
Collapse
|
2
|
Dennehy R, Duggan N, Dignam S, McCormack S, Dillon E, Molony J, Romano M, Hou Y, Ardill L, Whelan MVX, Drulis‐Kawa Z, Ó'Cróinín T, Valvano MA, Berisio R, McClean S. Protein with negative surface charge distribution, Bnr1, shows characteristics of a DNA-mimic protein and may be involved in the adaptation of Burkholderia cenocepacia. Microbiologyopen 2022; 11:e1264. [PMID: 35212475 PMCID: PMC9060813 DOI: 10.1002/mbo3.1264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/14/2022] [Indexed: 11/11/2022] Open
Abstract
Adaptation of opportunistic pathogens to their host environment requires reprogramming of a vast array of genes to facilitate survival in the host. Burkholderia cenocepacia, a Gram-negative bacterium with a large genome of ∼8 Mb that colonizes environmental niches, is exquisitely adaptable to the hypoxic environment of the cystic fibrosis lung and survives in macrophages. We previously identified an immunoreactive acidic protein encoded on replicon 3, BCAS0292. Deletion of the BCAS0292 gene significantly altered the abundance of 979 proteins by 1.5-fold or more; 19 proteins became undetectable while 545 proteins showed ≥1.5-fold reduced abundance, suggesting the BCAS0292 protein is a global regulator. Moreover, the ∆BCAS0292 mutant showed a range of pleiotropic effects: virulence and host-cell attachment were reduced, antibiotic susceptibility was altered, and biofilm formation enhanced. Its growth and survival were impaired in 6% oxygen. In silico prediction of its three-dimensional structure revealed BCAS0292 presents a dimeric β-structure with a negative surface charge. The ΔBCAS0292 mutant displayed altered DNA supercoiling, implicated in global regulation of gene expression. Three proteins were identified in pull-downs with FLAG-tagged BCAS0292, including the Histone H1-like protein, HctB, which is recognized as a global transcriptional regulator. We propose that BCAS0292 protein, which we have named Burkholderia negatively surface-charged regulatory protein 1 (Bnr1), acts as a DNA-mimic and binds to DNA-binding proteins, altering DNA topology and regulating the expression of multiple genes, thereby enabling the adaptation of B. cenocepacia to highly diverse environments.
Collapse
Affiliation(s)
- Ruth Dennehy
- Centre of Microbial Host InteractionsInstitute of Technology TallaghtDublinIreland
| | - Niamh Duggan
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
- UCD Conway Institute of Biomolecular and Biomedical ResearchUniversity College DublinBelfield, DublinIreland
| | - Simon Dignam
- Centre of Microbial Host InteractionsInstitute of Technology TallaghtDublinIreland
| | - Sarah McCormack
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
- UCD Conway Institute of Biomolecular and Biomedical ResearchUniversity College DublinBelfield, DublinIreland
| | - Eugene Dillon
- UCD Conway Institute of Biomolecular and Biomedical ResearchUniversity College DublinBelfield, DublinIreland
| | - Jessica Molony
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
| | - Maria Romano
- Institute of Biostructures and BioimagingNational Research CouncilNaplesItaly
| | - Yueran Hou
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
- UCD Conway Institute of Biomolecular and Biomedical ResearchUniversity College DublinBelfield, DublinIreland
| | - Laura Ardill
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
| | - Matthew V. X. Whelan
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
| | - Zuzanna Drulis‐Kawa
- Department of Pathogen Biology and Immunology, Institute of Genetics and MicrobiologyUniversity of WroclawWroclawPoland
| | - Tadhg Ó'Cróinín
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
| | - Miguel A. Valvano
- School of Medicine, Dentistry and Biomedical Sciences, Wellcome‐Wolfson Institute for Experimental MedicineQueen's University BelfastBelfastUK
| | - Rita Berisio
- Institute of Biostructures and BioimagingNational Research CouncilNaplesItaly
| | - Siobhán McClean
- Centre of Microbial Host InteractionsInstitute of Technology TallaghtDublinIreland
- School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland
- UCD Conway Institute of Biomolecular and Biomedical ResearchUniversity College DublinBelfield, DublinIreland
| |
Collapse
|
3
|
Flores-Vega VR, Vargas-Roldán SY, Lezana-Fernández JL, Lascurain R, Santos-Preciado JI, Rosales-Reyes R. Bacterial Subversion of Autophagy in Cystic Fibrosis. Front Cell Infect Microbiol 2021; 11:760922. [PMID: 34692569 PMCID: PMC8531276 DOI: 10.3389/fcimb.2021.760922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/20/2021] [Indexed: 11/13/2022] Open
Abstract
Cystic fibrosis (CF) is a genetic disease affecting more than 70,000 people worldwide. It is caused by a mutation in the cftr gene, a chloride ion transporter localized in the plasma membrane of lung epithelial cells and other organs. The loss of CFTR function alters chloride, bicarbonate, and water transport through the plasma membrane, promoting the production of a thick and sticky mucus in which bacteria including Pseudomonas aeruginosa and Burkholderia cenocepacia can produce chronic infections that eventually decrease the lung function and increase the risk of mortality. Autophagy is a well-conserved lysosomal degradation pathway that mediates pathogen clearance and plays an important role in the control of bacterial infections. In this mini-review, we describe the principal strategies used by P. aeruginosa and B. cenocepacia to survive and avoid microbicidal mechanisms within the autophagic pathway leading to the establishment of chronic inflammatory immune responses that gradually compromise the lung function and the life of CF patients.
Collapse
Affiliation(s)
- Verónica Roxana Flores-Vega
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Escuela de Ciencias de la Salud, Universidad del Valle de México, Campus Coyoacán, Mexico City, Mexico
| | - Silvia Yalid Vargas-Roldán
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City, Mexico
| | - José Luis Lezana-Fernández
- Laboratorio de Fisiología Respiratoria y la Clínica de Fibrosis Quística, Hospital Infantil de México Federico Gómez, Mexico City, Mexico.,Dirección Médica, Asociación Mexicana de Fibrosis Quística, Mexico City, Mexico
| | - Ricardo Lascurain
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Ignacio Santos-Preciado
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Roberto Rosales-Reyes
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| |
Collapse
|
4
|
Walpole GFW, Plumb JD, Chung D, Tang B, Boulay B, Osborne DG, Piotrowski JT, Catz SD, Billadeau DD, Grinstein S, Jaumouillé V. Inactivation of Rho GTPases by Burkholderia cenocepacia Induces a WASH-Mediated Actin Polymerization that Delays Phagosome Maturation. Cell Rep 2021; 31:107721. [PMID: 32492429 PMCID: PMC7315377 DOI: 10.1016/j.celrep.2020.107721] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 04/30/2020] [Accepted: 05/12/2020] [Indexed: 02/02/2023] Open
Abstract
Burkholderia cenocepacia is an opportunistic bacterial pathogen that causes severe pulmonary infections in cystic fibrosis and chronic granulomatous disease patients. B. cenocepacia can survive inside infected macrophages within the B. cenocepacia-containing vacuole (BcCV) and to elicit a severe inflammatory response. By inactivating the host macrophage Rho GTPases, the bacterial effector TecA causes depolymerization of the cortical actin cytoskeleton. In this study, we find that B. cenocepacia induces the formation of large cytosolic F-actin clusters in infected macrophages. Cluster formation requires the nucleation-promoting factor WASH, the Arp2/3 complex, and TecA. Inactivation of Rho GTPases by bacterial toxins is necessary and sufficient to induce the formation of the cytosolic actin clusters. By hijacking WASH and Arp2/3 activity, B. cenocepacia disrupts interactions with the endolysosomal system, thereby delaying the maturation of the BcCV.
Collapse
Affiliation(s)
- Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jonathan D Plumb
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Daniel Chung
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Brandon Tang
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Benoit Boulay
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Douglas G Osborne
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
| | - Joshua T Piotrowski
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
| | - Sergio D Catz
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, MB-215, La Jolla, CA 92037, USA
| | - Daniel D Billadeau
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Valentin Jaumouillé
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| |
Collapse
|
5
|
Rosales-Reyes R, Garza-Villafuerte P, Vences-Vences D, Aubert DF, Aca-Teutle R, Ortiz-Navarrete VF, Bonifaz LC, Carrero-Sánchez JC, Olivos-García A, Valvano MA, Santos-Preciado JI. Interferon-gamma-activated macrophages infected with Burkholderia cenocepacia process and present bacterial antigens to T-cells by class I and II major histocompatibility complex molecules. Emerg Microbes Infect 2021; 9:2000-2012. [PMID: 32873215 PMCID: PMC7534305 DOI: 10.1080/22221751.2020.1818632] [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] [Indexed: 12/21/2022]
Abstract
Burkholderia cenocepacia is an emerging opportunistic pathogen for people with cystic fibrosis and chronic granulomatous disease. Intracellular survival in macrophages within a membrane-bound vacuole (BcCV) that delays acidification and maturation into lysosomes is a hallmark of B. cenocepacia infection. Intracellular B. cenocepacia induce an inflammatory response leading to macrophage cell death by pyroptosis through the secretion of a bacterial deamidase that results in the activation of the pyrin inflammasome. However, how or whether infected macrophages can process and present B. cenocepacia antigens to activate T-cells has not been explored. Engulfed bacterial protein antigens are cleaved into small peptides in the late endosomal major histocompatibility class II complex (MHC) compartment (MIIC). Here, we demonstrate that BcCVs and MIICs have overlapping features and that interferon-gamma-activated macrophages infected with B. cenocepacia can process bacterial antigens for presentation by class II MHC molecules to CD4+ T-cells and by class I MHC molecules to CD8+ T-cells. Infected macrophages also release processed bacterial peptides into the extracellular medium, stabilizing empty class I MHC molecules of bystander cells. Together, we conclude that BcCVs acquire MIIC characteristics, supporting the notion that macrophages infected with B. cenocepacia contribute to establishing an adaptive immune response against the pathogen.
Collapse
Affiliation(s)
- Roberto Rosales-Reyes
- Facultad de Medicina, Unidad de Investigación en Medicina Experimental, Universidad Nacional Autónoma de México, Mexico City, México
| | - Paola Garza-Villafuerte
- Facultad de Medicina, Unidad de Investigación en Medicina Experimental, Universidad Nacional Autónoma de México, Mexico City, México
| | - Daniela Vences-Vences
- Facultad de Medicina, Unidad de Investigación en Medicina Experimental, Universidad Nacional Autónoma de México, Mexico City, México
| | - Daniel F Aubert
- Department of Microbiology and Immunology, The University of Western Ontario, London, Canada
| | - Rubi Aca-Teutle
- Facultad de Medicina, Unidad de Investigación en Medicina Experimental, Universidad Nacional Autónoma de México, Mexico City, México
| | - Vianney F Ortiz-Navarrete
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, México
| | - Laura C Bonifaz
- Unidad de Investigación Médica en Inmunoquímica Hospital de Especialidades Centro Médico Nacional Siglo XXI, IMSS, Mexico City, Mexico
| | | | - Alfonso Olivos-García
- Facultad de Medicina, Unidad de Investigación en Medicina Experimental, Universidad Nacional Autónoma de México, Mexico City, México
| | - Miguel A Valvano
- Department of Microbiology and Immunology, The University of Western Ontario, London, Canada.,The Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - José Ignacio Santos-Preciado
- Facultad de Medicina, Unidad de Investigación en Medicina Experimental, Universidad Nacional Autónoma de México, Mexico City, México
| |
Collapse
|
6
|
Galosi L, Attili AR, Perrucci S, Origgi FC, Tambella AM, Rossi G, Cuteri V, Napoleoni M, Mandolini NA, Perugini G, Loehr VJT. Health assessment of wild speckled dwarf tortoises, CHERSOBIUS SIGNATUS. BMC Vet Res 2021; 17:102. [PMID: 33663511 PMCID: PMC7934230 DOI: 10.1186/s12917-021-02800-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 02/16/2021] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND In free-ranging reptile populations, bacterial, fungal, viral and parasitic pathogens may affect hosts through impairment in movements, thermoregulation, reproduction, survival, and population dynamics. The speckled dwarf tortoise (Chersobius [Homopus] signatus) is a threatened species that is mostly restricted to the Succulent Karoo biome in South Africa, and little information on pathogens of this species is available yet. We derived baseline parameters for five males and five females that were captured to genetically enhance a conservation breeding program in Europe. Upon collection of the tortoises, ticks were removed and identified. Immediately upon arrival in Europe, ocular, nasal, oral and cloacal swabs were taken for viral, bacteriological and mycological examinations. Fecal samples were collected before and 1 month after fenbendazole treatment, and analyzed for parasites. A panel of PCR, aiming to detect herpesviruses, adenoviruses and iridoviruses, was carried out. RESULTS Samples were negative for viruses, while bacteriological examination yielded detectable growth in 82.5% of the swabs with a mean load of 16 × 107 ± 61 × 108 colony forming units (CFU) per swab, representing 34 bacterial species. Cloacal and oral swabs yielded higher detectable growth loads than nasal and ocular swabs, but no differences between sexes were observed. Fungi and yeasts (mean load 5 × 103 ± 13 × 103 CFU/swab) were detected in 25% of the swabs. All pre-treatment fecal samples were positive for oxyurid eggs, ranging from 200 to 2400 eggs per gram of feces, whereas after the treatment a significantly reduced egg count (90-100% reduction) was found in seven out of 10 individuals. One remaining individual showed 29% reduction, and two others had increased egg counts. In five tortoises, Nycthocterus spp. and coccidian oocysts were also identified. Soft ticks were identified as Ornithodoros savignyi. CONCLUSIONS Our baseline data from clinically healthy individuals will help future studies to interpret prevalences of microorganisms in speckled dwarf tortoise populations. The study population did not appear immediately threatened by current parasite presence.
Collapse
Affiliation(s)
- Livio Galosi
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024, Matelica, Italy.
| | - Anna Rita Attili
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024, Matelica, Italy
| | - Stefania Perrucci
- Department of Veterinary Science, University of Pisa, 56126, Pisa, Italy
| | - Francesco C Origgi
- Centre for Fish and Wildlife Health (FIWI), DIP, Vetsuisse Faculty, University of Bern, 3001, Bern, Switzerland
| | - Adolfo Maria Tambella
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024, Matelica, Italy
| | - Giacomo Rossi
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024, Matelica, Italy
| | - Vincenzo Cuteri
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024, Matelica, Italy
| | - Maira Napoleoni
- Experimental Zooprophylactic Institute (IZS) of Umbria and Marche 'Togo Rosati', 06126, Perugia, Italy
| | | | - Gianni Perugini
- Experimental Zooprophylactic Institute (IZS) of Umbria and Marche 'Togo Rosati', 06126, Perugia, Italy
| | - Victor J T Loehr
- Dwarf Tortoise Conservation, Kwikstaartpad 1, 3403ZH, IJsselstein, Netherlands
| |
Collapse
|
7
|
Gasdermin D restricts Burkholderia cenocepacia infection in vitro and in vivo. Sci Rep 2021; 11:855. [PMID: 33441602 PMCID: PMC7807041 DOI: 10.1038/s41598-020-79201-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 11/23/2020] [Indexed: 01/29/2023] Open
Abstract
Burkholderia cenocepacia (B. cenocepacia) is an opportunistic bacterium; causing severe life threatening systemic infections in immunocompromised individuals including cystic fibrosis patients. The lack of gasdermin D (GSDMD) protects mice against endotoxin lipopolysaccharide (LPS) shock. On the other hand, GSDMD promotes mice survival in response to certain bacterial infections. However, the role of GSDMD during B. cenocepacia infection is not yet determined. Our in vitro study shows that GSDMD restricts B. cenocepacia replication within macrophages independent of its role in cell death through promoting mitochondrial reactive oxygen species (mROS) production. mROS is known to stimulate autophagy, hence, the inhibition of mROS or the absence of GSDMD during B. cenocepacia infections reduces autophagy which plays a critical role in the restriction of the pathogen. GSDMD promotes inflammation in response to B. cenocepacia through mediating the release of inflammasome dependent cytokine (IL-1β) and an independent one (CXCL1) (KC). Additionally, different B. cenocepacia secretory systems (T3SS, T4SS, and T6SS) contribute to inflammasome activation together with bacterial survival within macrophages. In vivo study confirmed the in vitro findings and showed that GSDMD restricts B. cenocepacia infection and dissemination and stimulates autophagy in response to B. cenocepacia. Nevertheless, GSDMD promotes lung inflammation and necrosis in response to B. cenocepacia without altering mice survival. This study describes the double-edged functions of GSDMD in response to B. cenocepacia infection and shows the importance of GSDMD-mediated mROS in restriction of B. cenocepacia.
Collapse
|
8
|
Ganesh PS, Vishnupriya S, Vadivelu J, Mariappan V, Vellasamy KM, Shankar EM. Intracellular survival and innate immune evasion of Burkholderia cepacia: Improved understanding of quorum sensing-controlled virulence factors, biofilm, and inhibitors. Microbiol Immunol 2020; 64:87-98. [PMID: 31769530 DOI: 10.1111/1348-0421.12762] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/18/2019] [Accepted: 11/21/2019] [Indexed: 12/25/2022]
Abstract
Burkholderia cepacia complex (Bcc) are opportunistic pathogens implicated with nosocomial infections, and high rates of morbidity and mortality, especially in individuals with cystic fibrosis (CF). B. cepacia are naturally resistant to different classes of antibiotics, and can subvert the host innate immune responses by producing quorum sensing (QS) controlled virulence factors and biofilms. It still remains a conundrum as to how exactly the bacterium survives the intracellular environment within the host cells of CF patients and immunocompromised individuals although the bacterium can invade human lung epithelial cells, neutrophils, and murine macrophages. The mechanisms associated with intracellular survival in the airway epithelial cells and the role of QS and virulence factors in B. cepacia infections in cystic fibrosis remain largely unclear. The current review focuses on understanding the role of QS-controlled virulence factors and biofilms, and provides additional impetus to understanding the potentials of QS-inhibitory strategies against B. cepacia.
Collapse
Affiliation(s)
- Pitchaipillai Sankar Ganesh
- Division of Infection Biology & Medical Microbiology, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
| | - Sivakumar Vishnupriya
- Division of Infection Biology & Medical Microbiology, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Vanitha Mariappan
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kumutha M Vellasamy
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Esaki M Shankar
- Division of Infection Biology & Medical Microbiology, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
| |
Collapse
|
9
|
Lim BA, Lopez A, Buensalido JA. Refractory Burkholderia cepacia bacteraemia from a consolidation pneumonia lasting more than 7 weeks, successfully treated with systemic antibiotics and nebulised meropenem. BMJ Case Rep 2019; 12:12/8/e229566. [PMID: 31377717 DOI: 10.1136/bcr-2019-229566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
We present a case of a 55-year-old Filipino man who was transferred from another institution where he was recently diagnosed with Crohn's disease but not started on any immunosuppressants. He underwent laparoscopic cholecystectomy with T-tube placement a few weeks prior to admission. On workup, abdominal CT scan was unremarkable, but blood cultures on the third hospital day grew Burkholderia cepacia Antibiotic regimen was shifted to ceftazidime and levofloxacin. The bacteraemia and febrile episodes persisted despite removal of the central line and T tube. White blood cell scan and chest CT scan showed left-sided consolidation pneumonia. Blood cultures continued to grow B. cepacia despite shifting to meropenem and trimethoprim-sulfamethoxazole. Meropenem nebulisation at 250 mg every 12 hours was added to the regimen on the third week then oral minocycline was added on the fourth week due to persistence of bacteraemia. He subsequently developed a small vegetation on the aortic valve, so amikacin was added. Fever lysed on the sixth week, but the B. cepacia bacteraemia persisted, clearing only on the 51st hospital day. The patient was discharged with a plan to continue antibiotics, including meropenem nebulisation, for 6 more weeks. On follow-up, the patient had no recurrence of fever. There was also resolution of consolidation on chest CT scan and disappearance of vegetation on echocardiography.
Collapse
Affiliation(s)
- Bryan Albert Lim
- Department of Medicine (Division of Infectious Diseases), University of the Philippines-Philippine General Hospital, Manila, Philippines
| | - Adelaine Lopez
- Department of Medicine (Division of Infectious Diseases), University of the Philippines-Philippine General Hospital, Manila, Philippines
| | - Joseph Adrian Buensalido
- Department of Medicine (Division of Infectious Diseases), University of the Philippines-Philippine General Hospital, Manila, Philippines
| |
Collapse
|
10
|
Burkholderia cenocepacia Induces Macropinocytosis to Enter Macrophages. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4271560. [PMID: 29850514 PMCID: PMC5937589 DOI: 10.1155/2018/4271560] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 03/14/2018] [Indexed: 11/30/2022]
Abstract
Burkholderia cenocepacia is an opportunistic pathogen that infects individuals with cystic fibrosis, chronic granulomatous disease, and other immunocompromised states. B. cenocepacia survives in macrophages in membrane-bound vacuoles; however, the mechanism by which B. cenocepacia gains entry into macrophages remains unknown. After macrophage internalization, survival of B. cenocepacia within a bacteria-containing membrane vacuole (BcCV) is associated with its ability to arrest the maturation of the BcCV. In this study, we show that B. cenocepacia induces localized membrane ruffling, macropinocytosis, and macropinosomes-like compartments upon contact with the macrophage. The Type 3 Secretion System (T3SS) of B. cenocepacia contributes to macrophage entry and macropinosome-like compartment formation. These data demonstrate the ability of Burkholderia to enter macrophages through the induction of macropinocytosis.
Collapse
|
11
|
Seveau S, Turner J, Gavrilin MA, Torrelles JB, Hall-Stoodley L, Yount JS, Amer AO. Checks and Balances between Autophagy and Inflammasomes during Infection. J Mol Biol 2017; 430:174-192. [PMID: 29162504 DOI: 10.1016/j.jmb.2017.11.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 11/05/2017] [Accepted: 11/09/2017] [Indexed: 12/24/2022]
Abstract
Autophagy and inflammasome complex assembly are physiological processes that control homeostasis, inflammation, and immunity. Autophagy is a ubiquitous pathway that degrades cytosolic macromolecules or organelles, as well as intracellular pathogens. Inflammasomes are multi-protein complexes that assemble in the cytosol of cells upon detection of pathogen- or danger-associated molecular patterns. A critical outcome of inflammasome assembly is the activation of the cysteine protease caspase-1, which activates the pro-inflammatory cytokine precursors pro-IL-1β and pro-IL-18. Studies on chronic inflammatory diseases, heart diseases, Alzheimer's disease, and multiple sclerosis revealed that autophagy and inflammasomes intersect and regulate each other. In the context of infectious diseases, however, less is known about the interplay between autophagy and inflammasome assembly, although it is becoming evident that pathogens have evolved multiple strategies to inhibit and/or subvert these pathways and to take advantage of their intricate crosstalk. An improved appreciation of these pathways and their subversion by diverse pathogens is expected to help in the design of anti-infective therapeutic interventions.
Collapse
Affiliation(s)
- Stephanie Seveau
- Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA; Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA.
| | - Joanne Turner
- Texas Biomedical Research Institute, San Antonio, TX 78227, USA
| | - Mikhail A Gavrilin
- Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA; Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH, USA
| | | | - Luanne Hall-Stoodley
- Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA; Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA; Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| | - Amal O Amer
- Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA; Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| |
Collapse
|
12
|
Macrophages, but not neutrophils, are critical for proliferation of Burkholderia cenocepacia and ensuing host-damaging inflammation. PLoS Pathog 2017. [PMID: 28651010 PMCID: PMC5501683 DOI: 10.1371/journal.ppat.1006437] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Bacteria of the Burkholderia cepacia complex (Bcc) can cause devastating pulmonary infections in cystic fibrosis (CF) patients, yet the precise mechanisms underlying inflammation, recurrent exacerbations and transition from chronic stages to acute infection and septicemia are not known. Bcc bacteria are generally believed to have a predominant extracellular biofilm life style in infected CF lungs, similar to Pseudomonas aeruginosa, but this has been challenged by clinical observations which show Bcc bacteria predominantly in macrophages. More recently, Bcc bacteria have emerged in nosocomial infections of patients hospitalized for reasons unrelated to CF. Research has abundantly shown that Bcc bacteria can survive and replicate in mammalian cells in vitro, yet the importance of an intracellular life style during infection in humans is unknown. Here we studied the contribution of innate immune cell types to fatal pro-inflammatory infection caused by B. cenocepacia using zebrafish larvae. In strong contrast to the usual protective role for macrophages against microbes, our results show that these phagocytes significantly worsen disease outcome. We provide new insight that macrophages are critical for multiplication of B. cenocepacia in the host and for development of a fatal, pro-inflammatory response that partially depends on Il1-signalling. In contrast, neutrophils did not significantly contribute to disease outcome. In subcutaneous infections that are dominated by neutrophil-driven phagocytosis, the absence of a functional NADPH oxidase complex resulted in a small but measurably higher increase in bacterial growth suggesting the oxidative burst helps limit bacterial multiplication; however, neutrophils were unable to clear the bacteria. We suggest that paradigm-changing approaches are needed for development of novel antimicrobials to efficiently disarm intracellular bacteria of this group of highly persistent, opportunistic pathogens.
Collapse
|
13
|
Kandel SL, Firrincieli A, Joubert PM, Okubara PA, Leston ND, McGeorge KM, Mugnozza GS, Harfouche A, Kim SH, Doty SL. An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes. Front Microbiol 2017; 8:386. [PMID: 28348550 PMCID: PMC5347143 DOI: 10.3389/fmicb.2017.00386] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/23/2017] [Indexed: 11/13/2022] Open
Abstract
Microbial communities in the endosphere of Salicaceae plants, poplar (Populus trichocarpa) and willow (Salix sitchensis), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici, and Pythium ultimum. Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas, and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.
Collapse
Affiliation(s)
- Shyam L Kandel
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| | - Andrea Firrincieli
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Pierre M Joubert
- Department of Biology, University of Washington Seattle, WA, USA
| | - Patricia A Okubara
- Wheat Health, Genetics and Quality Research Unit, USDA-ARS Pullman, WA, USA
| | - Natalie D Leston
- Department of Plant Pathology, Washington State University Pullman, WA, USA
| | - Kendra M McGeorge
- Department of Plant Pathology, Washington State University Pullman, WA, USA
| | - Giuseppe S Mugnozza
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Antoine Harfouche
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Soo-Hyung Kim
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| | - Sharon L Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| |
Collapse
|
14
|
Mahenthiralingam E, Vandamme P. Taxonomy and pathogenesis of the Burkholderia cepacia complex. Chron Respir Dis 2016; 2:209-17. [PMID: 16541604 DOI: 10.1191/1479972305cd053ra] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Patients with cystic fibrosis (CF) are susceptible to chronic respiratory infection with a number of bacterial pathogens. The Burkholderia cepacia complex bacteria are problematic CF pathogens because (i) they are very resistant to antibiotics, making respiratory infection difficult to treat and eradicate; (ii) infection with these bacteria is associated with high mortality in CF; (iii) they may spread from one CF patient to another, leading to considerable problems for both patients and carers; and (iv) B. cepacia complex bacteria are difficult to identify and nine new species have now been found to constitute isolates originally identified as ‘B. cepacia’ based on their phenotypic properties. Here we review the changes that have occurred in the taxonomy of the B. cepacia complex and the pathogenic factors these bacteria possess. While the taxonomy of the B.cepacia complex has advanced considerably with the development of accurate methods for their identification, the pathogenic mechanisms employed by these CF pathogens are only just beginning to be explored at the molecular level. Several virulence factors have been defined for B. cenocepacia (the dominant CF pathogen within the complex); however, knowledge of the disease mechanisms employed by other B. cepacia complex species is limited. The recent determination of the complete genome sequences for several of the B. cepacia complex species should greatly enhance our ability to study these problematic CF pathogens.
Collapse
|
15
|
Aubert DF, Valvano MA, Hu S. Quantification of type VI secretion system activity in macrophages infected with Burkholderia cenocepacia. Microbiology (Reading) 2015; 161:2161-73. [DOI: 10.1099/mic.0.000174] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
16
|
Dixon EF, Hall RA. Noisy neighbourhoods: quorum sensing in fungal-polymicrobial infections. Cell Microbiol 2015; 17:1431-41. [PMID: 26243526 PMCID: PMC4973845 DOI: 10.1111/cmi.12490] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 06/26/2015] [Accepted: 07/17/2015] [Indexed: 02/06/2023]
Abstract
Quorum sensing was once considered a way in which a species was able to sense its cell density and regulate gene expression accordingly. However, it is now becoming apparent that multiple microbes can sense particular quorum-sensing molecules, enabling them to sense and respond to other microbes in their neighbourhood. Such interactions are significant within the context of polymicrobial disease, in which the competition or cooperation of microbes can alter disease progression. Fungi comprise a small but important component of the human microbiome and are in constant contact with bacteria and viruses. The discovery of quorum-sensing pathways in fungi has led to the characterization of a number of interkingdom quorum-sensing interactions. Here, we review the recent developments in quorum sensing in medically important fungi, and the implications these interactions have on the host's innate immune response.
Collapse
Affiliation(s)
- Emily F Dixon
- Institute of Microbiology and Infection, and School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Rebecca A Hall
- Institute of Microbiology and Infection, and School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| |
Collapse
|
17
|
Abstract
Burkholderia cepacia complex (Bcc) species are a group of Gram-negative opportunistic pathogens that infect the airways of cystic fibrosis patients, and occasionally they infect other immunocompromised patients. Bcc bacteria display high-level multidrug resistance and chronically persist in the infected host while eliciting robust inflammatory responses. Studies using macrophages, neutrophils, and dendritic cells, combined with advances in the genetic manipulation of these bacteria, have increased our understanding of the molecular mechanisms of virulence in these pathogens and the molecular details of cell-host responses triggering inflammation. This article discusses our current view of the intracellular survival of Burkholderia cenocepacia within macrophages.
Collapse
Affiliation(s)
- Miguel A. Valvano
- Centre for Infection and Immunity, Queen’s University Belfast, Belfast, BT9 7AE, UK
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| |
Collapse
|
18
|
Alipour N, Gaeini N, Taner A, Yıldız F, Masseret S, Malfertheiner P. Retracted: Vacuoles ofAcanthamoeba castellaniiBehave as a Specialized Shelter (host) forHelicobacter pylori. Helicobacter 2015. [DOI: 10.1111/hel.12233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
Affiliation(s)
- Nader Alipour
- Department of Biotechnology; METU; Ankara Turkey
- Department of Medical Microbiology; Faculty of Medicine; Giresun university; Giresun Turkey
| | - Nasrin Gaeini
- Department of Radiology; Trakya University; Edirne Turkey
| | - Abbas Taner
- Department of Medical Microbiology; Yuksek ihtisas university; Ankara Turkey
| | - Fatih Yıldız
- Department of Biotechnology; METU; Ankara Turkey
| | - Sadegh Masseret
- Digestive Disease Research Center of Tehran Medical Science university; Shariati hospital; Tehran IRAN
| | - Peter Malfertheiner
- Digestive Disease Department; Otto von Guarig Clinical University; Magdeburg Germany
| |
Collapse
|
19
|
Localization of Burkholderia cepacia complex bacteria in cystic fibrosis lungs and interactions with Pseudomonas aeruginosa in hypoxic mucus. Infect Immun 2014; 82:4729-45. [PMID: 25156735 DOI: 10.1128/iai.01876-14] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The localization of Burkholderia cepacia complex (Bcc) bacteria in cystic fibrosis (CF) lungs, alone or during coinfection with Pseudomonas aeruginosa, is poorly understood. We performed immunohistochemistry for Bcc and P. aeruginosa bacteria on 21 coinfected or singly infected CF lungs obtained at transplantation or autopsy. Parallel in vitro experiments examined the growth of two Bcc species, Burkholderia cenocepacia and Burkholderia multivorans, in environments similar to those occupied by P. aeruginosa in the CF lung. Bcc bacteria were predominantly identified in the CF lung as single cells or small clusters within phagocytes and mucus but not as "biofilm-like structures." In contrast, P. aeruginosa was identified in biofilm-like masses, but densities appeared to be reduced during coinfection with Bcc bacteria. Based on chemical analyses of CF and non-CF respiratory secretions, a test medium was defined to study Bcc growth and interactions with P. aeruginosa in an environment mimicking the CF lung. When test medium was supplemented with alternative electron acceptors under anaerobic conditions, B. cenocepacia and B. multivorans used fermentation rather than anaerobic respiration to gain energy, consistent with the identification of fermentation products by high-performance liquid chromatography (HPLC). Both Bcc species also expressed mucinases that produced carbon sources from mucins for growth. In the presence of P. aeruginosa in vitro, both Bcc species grew anaerobically but not aerobically. We propose that Bcc bacteria (i) invade a P. aeruginosa-infected CF lung when the airway lumen is anaerobic, (ii) inhibit P. aeruginosa biofilm-like growth, and (iii) expand the host bacterial niche from mucus to also include macrophages.
Collapse
|
20
|
Andree KB, Rodgers CJ, Furones D, Gisbert E. Co-infection with Pseudomonas anguilliseptica and Delftia acidovorans in the European eel, Anguilla anguilla (L.): a case history of an illegally trafficked protected species. JOURNAL OF FISH DISEASES 2013; 36:647-656. [PMID: 23297744 DOI: 10.1111/jfd.12066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/23/2012] [Accepted: 11/03/2012] [Indexed: 06/01/2023]
Abstract
Inspections by customs agents at Barcelona airport discovered 420 kg of contraband glass eels prepared for shipment to Hong Kong. After confiscation of these animals by police, they were transported to holding facilities to be maintained until after a judicial hearing. Upon arrival, they were separated into two groups and held under ambient flow-through conditions in fresh water. During their captivity period, several peaks in mortality occurred and multiple bacterial strains were isolated from moribund animals. Sequencing of 16S rDNA was used to determine specific identity of the isolates. An initial isolation of Pseudomonas anguilliseptica was treated with oxytetracycline. A subsequent isolation of Delftia acidovorans proved resistant to oxytetracycline and was treated with gentamicin in combination with sulphadiazine-trimethoprim. Once the health condition of the animals was stabilized, they were partitioned into groups and subsequently released as part of a restocking effort for the species following the guidelines of Regulation (EC) 1100/2007 (Anon 2007). This represents the first record for both bacterial species in the host Anguilla anguilla in the Spanish Mediterranean.
Collapse
Affiliation(s)
- K B Andree
- IRTA, Sant Carles de la Rápita, Tarragona, Spain.
| | | | | | | |
Collapse
|
21
|
Conway SP, Brownlee KG, Denton M, Peckham DG. Antibiotic Treatment of Multidrug-Resistant Organisms in Cystic Fibrosis. ACTA ACUST UNITED AC 2012; 2:321-32. [PMID: 14719998 DOI: 10.1007/bf03256660] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Respiratory tract infection with eventual respiratory failure is the major cause of morbidity and mortality in cystic fibrosis (CF). Infective exacerbations need to be treated promptly and effectively to minimize potentially accelerated attrition of lung function. The choice of antibiotic depends on in vitro sensitivity patterns. However, physicians treating patients with CF are increasingly faced with infection with multidrug-resistant isolates of Pseudomonas aeruginosa. In addition, innately resistant organisms such as Burkholderia cepacia complex, Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans are becoming more prevalent. Infection with methicillin-resistant Staphylococcus aureus (MRSA) is also a problem. These changing patterns probably result from greater patient longevity and increased antibiotic use for acute exacerbations and maintenance care. Multidrug-resistant P. aeruginosa infection may be treated successfully by using two antibiotics with different mechanisms of action. In practice antibiotic choices have usually been made on a best-guess basis, but recent research suggests that more directed therapy can be achieved through the application of multiple-combination bactericidal testing (MCBT). Aerosol delivery of tobramycin for inhalation solution achieves high endobronchial concentrations that may overcome bacterial resistance as defined by standard laboratory protocols. Resistance to colistin is rare and this antibiotic should be seen as a valuable second-line drug to be reserved for multidrug-resistant P. aeruginosa. The efficacy of new antibiotic groups such as the macrolides needs to be evaluated.CF units should adopt strict segregation policies to interrupt person-to-person spread of B. cepacia complex. Treatment of panresistant strains is difficult and often arbitrary. Combination antibiotic therapy is recommended, usually tobramycin and high-dose meropenem and/or ceftazidime, but the choice of treatment regimen should always be guided by the clinical response.The clinical significance of S. maltophilia, A. xylosoxidans and MRSA infection in CF lung disease remains uncertain. If patients show clinical decline and are chronically colonized/infected with either of the former two pathogens, treatment is recommended but efficacy data are lacking. There are defined microbiological reasons for attempting eradication of MRSA but there are no proven deleterious effects of this infection on lung function in patients with CF. Various treatment protocols exist but none has been subject to a randomized, controlled trial. Multidrug-resistant microorganisms are an important and growing issue in the care of patients with CF. Each patient infected with such strains should be assessed individually and antibiotic treatment planned according to in vitro sensitivity, patient drug tolerance, and results of in vitro studies which may direct the physician to antibiotic combinations most likely to succeed.
Collapse
Affiliation(s)
- S P Conway
- Paediatric and Adult Regional Cystic Fibrosis Centres, St James' and Seacroft University Hospitals, Leeds, UK.
| | | | | | | |
Collapse
|
22
|
Flannagan RS. Burkholderia cenocepacia infection: disruption of phagocyte immune functions through Rho GTPase inactivation. Cell Adh Migr 2012; 6:297-301. [PMID: 22622109 DOI: 10.4161/cam.20487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phagocytosis is an important component of innate immunity that contributes to the eradication of infectious microorganisms; however, successful bacterial pathogens often evade different aspects of host immune responses. A common bacterial evasion strategy entails the production of toxins and/or effectors that disrupt normal host cell processes and because of their importance Rho-family GTPases are often targeted. Burkholderia cenocepacia, an opportunistic pathogen that has a propensity to infect cystic fibrosis patients, is an example of a pathogenic bacterium that has only recently been shown to disrupt Rho GTPase function in professional phagocytes. More specifically, B. cenocepacia disrupts Rac and Cdc42 seemingly through perturbation of guanine nucleotide exchange factor function. Inactivation of Rac, Cdc42 and conceivably other Rho GTPases seriously compromises phagocyte function.
Collapse
Affiliation(s)
- Ronald S Flannagan
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada.
| |
Collapse
|
23
|
Lynch KH, Dennis JJ. Cangene Gold Medal Award Lecture — Genomic analysis and modification ofBurkholderia cepaciacomplex bacteriophages1This article is based on a presentation by Dr. Karlene Lynch at the 61st Annual Meeting of the Canadian Society of Microbiologists in St. John’s, Newfoundland and Labrador, on 21 June 2011. Dr. Lynch was the recipient of the 2011 Cangene Gold Medal as the Canadian Graduate Student Microbiologist of the Year, an annual award sponsored by Cangene Corporation intended to recognize excellence in graduate research. Can J Microbiol 2012; 58:221-35. [DOI: 10.1139/w11-135] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The Burkholderia cepacia complex (Bcc) is a group of 17 Gram-negative predominantly environmental bacterial species that cause potentially fatal opportunistic infections in cystic fibrosis (CF) patients. Although its prevalence in these individuals is lower than that of Staphylococcus aureus and Pseudomonas aeruginosa , the Bcc remains a serious problem in the CF community because of the pathogenicity, transmissibility, and inherent antibiotic resistance of these organisms. An alternative treatment for Bcc infections that is currently being developed is phage therapy, the clinical use of viruses that infect bacteria. To assess the suitability of individual phage isolates for therapeutic use, the complete genome sequences of a panel of Bcc‐specific phages were determined and analyzed. These sequences encode a broad range of proteins with a gradient of relatedness to phage and bacterial gene products from Burkholderia and other genera. The majority of these phages were found not to encode virulence factors, and despite their predominantly temperate nature, a proof-of-principle experiment has shown that they may be modified to a lytic form. Both the genomic characterization and subsequent engineering of Bcc‐specific phages are fundamental to the development of an effective phage therapy strategy for these bacteria.
Collapse
Affiliation(s)
- Karlene H. Lynch
- 6-008 Centennial Centre for Interdisciplinary Science, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Jonathan J. Dennis
- 6-008 Centennial Centre for Interdisciplinary Science, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| |
Collapse
|
24
|
Tolman JS, Valvano MA. Global changes in gene expression by the opportunistic pathogen Burkholderia cenocepacia in response to internalization by murine macrophages. BMC Genomics 2012; 13:63. [PMID: 22321740 PMCID: PMC3296584 DOI: 10.1186/1471-2164-13-63] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 02/09/2012] [Indexed: 12/18/2022] Open
Abstract
Background Burkholderia cenocepacia is an opportunistic pathogen causing life-threatening infections in patients with cystic fibrosis. The bacterium survives within macrophages by interfering with endocytic trafficking and delaying the maturation of the B. cenocepacia-containing phagosome. We hypothesize that B. cenocepacia undergoes changes in gene expression after internalization by macrophages, inducing genes involved in intracellular survival and host adaptation. Results We examined gene expression by intracellular B. cenocepacia using selective capture of transcribed sequences (SCOTS) combined with microarray analysis. We identified 767 genes with significantly different levels of expression by intracellular bacteria, of which 330 showed increased expression and 437 showed decreased expression. Affected genes represented all aspects of cellular life including information storage and processing, cellular processes and signaling, and metabolism. In general, intracellular gene expression demonstrated a pattern of environmental sensing, bacterial response, and metabolic adaptation to the phagosomal environment. Deletion of various SCOTS-identified genes affected bacterial entry into macrophages and intracellular replication. We also show that intracellular B. cenocepacia is cytotoxic towards the macrophage host, and capable of spread to neighboring cells, a role dependent on SCOTS-identified genes. In particular, genes involved in bacterial motility, cobalamin biosynthesis, the type VI secretion system, and membrane modification contributed greatly to macrophage entry and subsequent intracellular behavior of B. cenocepacia. Conclusions B. cenocepacia enters macrophages, adapts to the phagosomal environment, replicates within a modified phagosome, and exhibits cytotoxicity towards the host cells. The analysis of the transcriptomic response of intracellular B. cenocepacia reveals that metabolic adaptation to a new niche plays a major role in the survival of B. cenocepacia in macrophages. This adaptive response does not require the expression of any specific virulence-associated factor, which is consistent with the opportunistic nature of this microorganism. Further investigation into the remaining SCOTS-identified genes will provide a more complete picture of the adaptive response of B. cenocepacia to the host cell environment.
Collapse
Affiliation(s)
- Jennifer S Tolman
- Infectious Diseases Research Group, Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | | |
Collapse
|
25
|
Abdulrahman BA, Khweek AA, Akhter A, Caution K, Kotrange S, Abdelaziz DHA, Newland C, Rosales-Reyes R, Kopp B, McCoy K, Montione R, Schlesinger LS, Gavrilin MA, Wewers MD, Valvano MA, Amer AO. Autophagy stimulation by rapamycin suppresses lung inflammation and infection by Burkholderia cenocepacia in a model of cystic fibrosis. Autophagy 2011; 7:1359-70. [PMID: 21997369 DOI: 10.4161/auto.7.11.17660] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cystic fibrosis (CF) is the most common inherited lethal disease of Caucasians which results in multi organ dysfunction. However, 85% of the deaths are due to pulmonary infections. Infection by Burkholderia cenocepacia (B. cepacia) is a particularly lethal threat to CF patients because it causes severe and persistent lung inflammation and is resistant to nearly all available antibiotics. In CFTR ΔF508 mouse macrophages, B. cepacia persists in vacuoles that do not fuse with the lysosomes and mediates increased production of IL-1β. It is believed that intracellular bacterial survival contributes to the persistence of the bacterium. Here we show for the first time that in wild-type macrophages but not in ΔF508 macrophages, many B. cepacia reside in autophagosomes that fuse with lysosomes at later stages of infection. Accordingly, association and intracellular survival of B. cepacia are higher in CFTR-ΔF508 (ΔF508) macrophages than in WT macrophages. An autophagosome is a compartment that engulfs non-functional organelles and parts of the cytoplasm then delivers them to the lysosome for degradation to produce nutrients during periods of starvation or stress. Furthermore, we show that B. cepacia downregulates autophagy genes in WT and ΔF508 macrophages. However, autophagy dysfunction is more pronounced in ΔF508 macrophages since they already have compromised autophagy activity. We demonstrate that the autophagy-stimulating agent, rapamycin markedly decreases B. cepacia infection in vitro by enhancing the clearance of B. cepacia via induced autophagy. In vivo, Rapamycin decreases bacterial burden in the lungs of CF mice and drastically reduces signs of lung inflammation. Together, our studies reveal that if efficiently activated, autophagy can control B. cepacia infection and ameliorate the associated inflammation. Therefore, autophagy is a novel target for new drug development for CF patients to control B. cepacia infection and accompanying inflammation.
Collapse
Affiliation(s)
- Basant A Abdulrahman
- Center for Microbial Interface Biology, Department of Microbial Infection, Ohio State University, Columbus, OH, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Cremer TJ, Shah P, Cormet-Boyaka E, Valvano MA, Butchar JP, Tridandapani S. Akt-mediated proinflammatory response of mononuclear phagocytes infected with Burkholderia cenocepacia occurs by a novel GSK3β-dependent, IκB kinase-independent mechanism. THE JOURNAL OF IMMUNOLOGY 2011; 187:635-43. [PMID: 21697459 DOI: 10.4049/jimmunol.1003034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The environmental bacterium Burkholderia cenocepacia causes opportunistic lung infections in immunocompromised individuals, particularly in patients with cystic fibrosis. Infections in these patients are associated with exacerbated inflammation leading to rapid decay of lung function, and in some cases resulting in cepacia syndrome, which is characterized by a fatal acute necrotizing pneumonia and sepsis. B. cenocepacia can survive intracellularly in macrophages by altering the maturation of the phagosome, but very little is known on macrophage responses to the intracellular infection. In this study, we have examined the role of the PI3K/Akt signaling pathway in B. cenocepacia-infected monocytes and macrophages. We show that PI3K/Akt activity was required for NF-κB activity and the secretion of proinflammatory cytokines during infection with B. cenocepacia. In contrast to previous observations in epithelial cells infected with other Gram-negative bacteria, Akt did not enhance IκB kinase or NF-κB p65 phosphorylation, but rather inhibited GSK3β, a negative regulator of NF-κB transcriptional activity. This novel mechanism of modulation of NF-κB activity may provide a unique therapeutic target for controlling excessive inflammation upon B. cenocepacia infection.
Collapse
Affiliation(s)
- Thomas J Cremer
- Department of Internal Medicine, The Ohio State University Medical Center, Columbus, OH 43210, USA
| | | | | | | | | | | |
Collapse
|
27
|
Christodoulou V, Messaritakis I, Svirinaki E, Tsatsanis C, Antoniou M. Leishmania infantum and Toxoplasma gondii: Mixed infection of macrophages in vitro and in vivo. Exp Parasitol 2011; 128:279-84. [PMID: 21354140 DOI: 10.1016/j.exppara.2011.02.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 02/11/2011] [Accepted: 02/21/2011] [Indexed: 11/18/2022]
Abstract
Although macrophages have a microbicidal role in the immune system they themselves can be infected by pathogens. Often a simultaneous infection by more than one microbe may occur in a single cell. This is the first report of coinfection of macrophages with Toxoplasma gondii and Leishmania infantum, in vitro and in vivo. L. infantum does not cause severe disease in mice but T. gondii, RH strain, is lethal. Cell culture studies using THP-1 macrophages dually infected in vitro revealed that 4.3% harbored both parasites 24h after infection. When mice were infected with both parasites on the same day 7.3% of the infected cells carried both parasites 7 days later. Yet, if mice were first infected with L. infantum and then with Toxoplasma (5 days post-infection) 18.7% of the macrophages hosted either parasite but concomitant infection could not be found and mice, already harboring L. infantum, survived Toxoplasma's lethal effect.
Collapse
Affiliation(s)
- Vasiliki Christodoulou
- Laboratory of Clinical Bacteriology Parasitology Zoonoses and Geographical Medicine, Faculty of Medicine, University of Crete, Crete, Greece
| | | | | | | | | |
Collapse
|
28
|
McKeon S, McClean S, Callaghan M. Macrophage responses to CF pathogens: JNK MAP kinase signaling by Burkholderia cepacia complex lipopolysaccharide. ACTA ACUST UNITED AC 2011; 60:36-43. [PMID: 20602636 DOI: 10.1111/j.1574-695x.2010.00712.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chronic bacterial colonization of the airways with opportunistic pathogens is the primary cause of morbidity and mortality in cystic fibrosis (CF) patients. Burkholderia cepacia complex (Bcc) organisms pose a particular challenge in CF lung disease, due in part to their ability to trigger a fulminant pneumonia. This study compares the U937 macrophage response to two Bcc species, B. cenocepacia and Burkholderia multivorans, against Pseudomonas aeruginosa and Staphylococcus aureus. The two Bcc strains demonstrated higher levels of U937 macrophage internalization compared with both P. aeruginosa and S. aureus. Both the Bcc strains also stimulated significantly greater levels of tumor necrosis factor-α and interleukin-1β from macrophages when compared with P. aeruginosa. Further examination of the macrophage response to B. multivorans demonstrated that the lipopolysaccharide component of these bacteria was a potent inducer of proinflammatory cytokines and was shown to signal predominantly through the c-Jun N-terminal kinase mitogen-activated protein kinase pathway. These studies further characterize the host response to Bcc and in particular B. multivorans, now the predominant Bcc species in many CF populations.
Collapse
Affiliation(s)
- Suzanne McKeon
- Centre of Microbial Host Interactions, ITT-Dublin, Dublin, Ireland
| | | | | |
Collapse
|
29
|
Kotrange S, Kopp B, Akhter A, Abdelaziz D, Abu Khweek A, Caution K, Abdulrahman B, Wewers MD, McCoy K, Marsh C, Loutet SA, Ortega X, Valvano MA, Amer AO. Burkholderia cenocepacia O polysaccharide chain contributes to caspase-1-dependent IL-1beta production in macrophages. J Leukoc Biol 2010; 89:481-8. [PMID: 21178113 DOI: 10.1189/jlb.0910513] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Burkholderia cenocepacia infections in CF patients involve heightened inflammation, fatal sepsis, and high antibiotic resistance. Proinflammatory IL-1β secretion is important in airway inflammation and tissue damage. However, little is known about this pathway in macrophages upon B. cenocepacia infection. We report here that murine macrophages infected with B. cenocepacia K56-2 produce proinflammatory cytokine IL-1β in a TLR4 and caspase-1-mediated manner. We also determined that the OPS (O antigen) of B. cenocepacia LPS contributes to IL-1β production and pyroptotic cell death. Furthermore, we showed that the malfunction of the CFTR channel augmented IL-1β production upon B. cenocepacia infection of murine macrophages. Taken together, we identified eukaryotic and bacterial factors that contribute to inflammation during B. cenocepacia infection, which may aid in the design of novel approaches to control pulmonary inflammation.
Collapse
Affiliation(s)
- Sheetal Kotrange
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Center for Microbial Interface Biology and the Department of Internal Medicine, Ohio State University, Columbus, Ohio 43210, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Pathogenicity, virulence factors, and strategies to fight against Burkholderia cepacia complex pathogens and related species. Appl Microbiol Biotechnol 2010; 87:31-40. [PMID: 20390415 DOI: 10.1007/s00253-010-2528-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 02/25/2010] [Accepted: 02/25/2010] [Indexed: 12/31/2022]
Abstract
The Burkholderia cepacia complex (Bcc) is a group of 17 closely related species of the beta-proteobacteria subdivision that emerged in the 1980s as important human pathogens, especially to patients suffering from cystic fibrosis. Since then, a remarkable progress has been achieved on the taxonomy and molecular identification of these bacteria. Although some progress have been achieved on the knowledge of the pathogenesis traits and virulence factors used by these bacteria, further work envisaging the identification of potential targets for the scientifically based design of new therapeutic strategies is urgently needed, due to the very difficult eradication of these bacteria with available therapies. An overview of these aspects of Bcc pathogenesis and opportunities for the design of future therapies is presented and discussed in this work.
Collapse
|
31
|
Abstract
The Burkholderia cepacia complex (Bcc) is a group of genetically related environmental bacteria that can cause chronic opportunistic infections in patients with cystic fibrosis (CF) and other underlying diseases. These infections are difficult to treat due to the inherent resistance of the bacteria to antibiotics. Bacteria can spread between CF patients through social contact and sometimes cause cepacia syndrome, a fatal pneumonia accompanied by septicemia. Burkholderia cenocepacia has been the focus of attention because initially it was the most common Bcc species isolated from patients with CF in North America and Europe. Today, B. cenocepacia, along with Burkholderia multivorans, is the most prevalent Bcc species in patients with CF. Given the progress that has been made in our understanding of B. cenocepacia over the past decade, we thought that it was an appropriate time to review our knowledge of the pathogenesis of B. cenocepacia, paying particular attention to the characterization of virulence determinants and the new tools that have been developed to study them. A common theme emerging from these studies is that B. cenocepacia establishes chronic infections in immunocompromised patients, which depend more on determinants mediating host niche adaptation than those involved directly in host cells and tissue damage.
Collapse
Affiliation(s)
- Slade A. Loutet
- Centre for Human Immunology, Department of Microbiology and Immunology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Miguel A. Valvano
- Centre for Human Immunology, Department of Microbiology and Immunology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
32
|
Huynh KK, Plumb JD, Downey GP, Valvano MA, Grinstein S. Inactivation of macrophage Rab7 by Burkholderia cenocepacia. J Innate Immun 2010; 2:522-33. [PMID: 20829607 DOI: 10.1159/000319864] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 08/03/2010] [Indexed: 02/02/2023] Open
Abstract
Strains of the Burkholderia cepacia complex can survive within macrophages by arresting the maturation of phagocytic vacuoles. The bacteria preclude fusion of the phagosome with lysosomes by a process that is poorly understood. Using murine macrophages, we investigated the stage at which maturation is arrested and analyzed the underlying mechanism. Vacuoles containing B. cenocepacia strain J2315, an isolate of the transmissible ET12 clone, recruited Rab5 and synthesized phosphatidylinositol-3-phosphate, indicating progression to the early phagosomal stage. Despite the fact that the B. cenocepacia-containing vacuoles rarely fused with lysosomes, they could nevertheless acquire the late phagosomal markers CD63 and Rab7. Fluorescence recovery after photobleaching and use of a probe that detects Rab7-guanosine triphosphate indicated that activation of Rab7 was impaired by B. cenocepacia, accounting at least in part for the inability of the vacuole to merge with lysosomes. The Rab7 defect was not due to excessive cholesterol accumulation and was confined to the infected vacuoles. Jointly, these experiments indicate that B. cenocepacia express virulence factors capable of interfering with Rab7 function and thereby with membrane traffic.
Collapse
Affiliation(s)
- Kassidy K Huynh
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | | | | | | | | |
Collapse
|
33
|
Clarke DJ, Ortega XP, Mackay CL, Valvano MA, Govan JRW, Campopiano DJ, Langridge-Smith P, Brown AR. Subdivision of the bacterioferritin comigratory protein family of bacterial peroxiredoxins based on catalytic activity. Biochemistry 2010; 49:1319-30. [PMID: 20078128 DOI: 10.1021/bi901703m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peroxiredoxins are ubiquitous proteins that catalyze the reduction of hydroperoxides, thus conferring resistance to oxidative stress. Using high-resolution mass spectrometry, we recently reclassified one such peroxiredoxin, bacterioferritin comigratory protein (BCP) of Escherichia coli, as an atypical 2-Cys peroxiredoxin that functions through the formation of an intramolecular disulfide bond between the active and resolving cysteine. An engineered E. coli BCP, which lacked the resolving cysteine, retained enzyme activity through a novel catalytic pathway. Unlike the active cysteine, the resolving cysteine of BCP peroxiredoxins is not conserved across all members of the family. To clarify the catalytic mechanism of native BCP enzymes that lack the resolving cysteine, we have investigated the BCP homologue of Burkholderia cenocepacia. We demonstrate that the B. cenocepacia BCP (BcBCP) homologue functions through a 1-Cys catalytic pathway. During catalysis, BcBCP can utilize thioredoxin as a reductant for the sulfenic acid intermediate. However, significantly higher peroxidase activity is observed utilizing glutathione as a resolving cysteine and glutaredoxin as a redox partner. Introduction of a resolving cysteine into BcBCP changes the activity from a 1-Cys pathway to an atypical 2-Cys pathway, analogous to the E. coli enzyme. In contrast to the native B. cenocepacia enzyme, thioredoxin is the preferred redox partner for this atypical 2-Cys variant. BCP-deficient B. cenocepacia exhibit a growth-phase-dependent hypersensitivity to oxidative killing. On the basis of sequence alignments, we believe that BcBCP described herein is representative of the major class of bacterial BCP peroxiredoxins. To our knowledge, this is the first detailed characterization of their catalytic activity. These studies support the subdivision of the BCP family of peroxiredoxins into two classes based on their catalytic activity.
Collapse
Affiliation(s)
- David J Clarke
- SIRCAMS, School of Chemistry, University of Edinburgh, Edinburgh, UK
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Vergunst AC, Meijer AH, Renshaw SA, O'Callaghan D. Burkholderia cenocepacia creates an intramacrophage replication niche in zebrafish embryos, followed by bacterial dissemination and establishment of systemic infection. Infect Immun 2010; 78:1495-508. [PMID: 20086083 PMCID: PMC2849400 DOI: 10.1128/iai.00743-09] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/05/2009] [Accepted: 01/09/2010] [Indexed: 11/20/2022] Open
Abstract
Bacteria belonging to the "Burkholderia cepacia complex" (Bcc) often cause fatal pulmonary infections in cystic fibrosis patients, yet little is know about the underlying molecular mechanisms. These Gram-negative bacteria can adopt an intracellular lifestyle, although their ability to replicate intracellularly has been difficult to demonstrate. Here we show that Bcc bacteria survive and multiply in macrophages of zebrafish embryos. Local dissemination by nonlytic release from infected cells was followed by bacteremia and extracellular replication. Burkholderia cenocepacia isolates belonging to the epidemic electrophoretic type 12 (ET12) lineage were highly virulent for the embryos; intravenous injection of <10 bacteria of strain K56-2 killed embryos within 3 days. However, small but significant differences between the clonal ET12 isolates K56-2, J2315, and BC7 were evident. In addition, the innate immune response in young embryos was sufficiently developed to control infection with other less virulent Bcc strains, such as Burkholderia vietnamiensis FC441 and Burkholderia stabilis LMG14294. A K56-2 cepR quorum-sensing regulator mutant was highly attenuated, and its ability to replicate and spread to neighboring cells was greatly reduced. Our data indicate that the zebrafish embryo is an excellent vertebrate model to dissect the molecular basis of intracellular replication and the early innate immune responses in this intricate host-pathogen interaction.
Collapse
Affiliation(s)
- Annette C Vergunst
- INSERM, ESPRI 26, UFR Médecine, CS83021, Avenue Kennedy, 30908 Nimes, France.
| | | | | | | |
Collapse
|
35
|
Construction of aminoglycoside-sensitive Burkholderia cenocepacia strains for use in studies of intracellular bacteria with the gentamicin protection assay. Appl Environ Microbiol 2010; 76:3170-6. [PMID: 20348312 DOI: 10.1128/aem.03024-09] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Burkholderia cenocepacia is a multidrug-resistant opportunistic pathogen that infects the airways of patients with cystic fibrosis (CF) and can survive intracellularly in macrophages and epithelial cells. The gentamicin protection assay, which relies on the poor ability of gentamicin or other aminoglycosides to permeate eukaryotic cell membranes, is traditionally employed to quantify intracellular bacteria. However, the high resistance of these bacteria to aminoglycosides hampers the use of the gentamicin protection assay to investigate intracellular infection by B. cenocepacia. Here, we report the construction of gentamicin-sensitive strains of B. cenocepacia carrying a deletion of the BCAL1674, BCAL1675, and BCAL1676 genes that form an operon encoding an AmrAB-OprA-like efflux pump. We show that bacteria carrying this deletion are hypersensitive to gentamicin and also delay phagolysosomal fusion upon infection of RAW 264.7 murine macrophages, as previously demonstrated for the parental strain. We also demonstrate for the first time that low concentrations of gentamicin can be used to effectively kill extracellular bacteria and reliably quantify the intracellular infection by B. cenocepacia, which can replicate in RAW 264.7 macrophages.
Collapse
|
36
|
Saldías MS, Valvano MA. Interactions of Burkholderia cenocepacia and other Burkholderia cepacia complex bacteria with epithelial and phagocytic cells. Microbiology (Reading) 2009; 155:2809-2817. [DOI: 10.1099/mic.0.031344-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Burkholderia cenocepacia is a member of the B. cepacia complex (Bcc), a group of opportunistic bacteria that infect the airways of patients with cystic fibrosis (CF) and are extraordinarily resistant to almost all clinically useful antibiotics. Infections in CF patients with Bcc bacteria generally lead to a more rapid decline in lung function, and in some cases to the ‘cepacia syndrome’, a virtually deadly exacerbation of the lung infection with systemic manifestations. These characteristics of Bcc bacteria contribute to higher morbidity and mortality in infected CF patients. In the last 10 years considerable progress has been made in understanding the interactions between Bcc bacteria and mammalian host cells. Bcc isolates can survive either intracellularly within eukaryotic cells or extracellularly in host tissues. They survive within phagocytes and respiratory epithelial cells, and they have the ability to breach the respiratory epithelium layer. Survival and persistence of Bcc bacteria within host cells and tissues are believed to play a key role in pulmonary infection and to contribute to the persistent inflammation observed in patients with CF. This review summarizes recent findings concerning the interaction between Bcc bacteria and epithelial and phagocytic cells.
Collapse
Affiliation(s)
- M. Soledad Saldías
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Miguel A. Valvano
- Department of Medicine, University of Western Ontario, London, ON N6A 5C1, Canada
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| |
Collapse
|
37
|
Saldías MS, Ortega X, Valvano MA. Burkholderia cenocepacia O antigen lipopolysaccharide prevents phagocytosis by macrophages and adhesion to epithelial cells. J Med Microbiol 2009; 58:1542-1548. [PMID: 19713359 DOI: 10.1099/jmm.0.013235-0] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chronic respiratory infections by the Burkholderia cepacia complex (Bcc) are of great concern to patients with cystic fibrosis. Bcc isolates may survive intracellularly within amoebae, respiratory epithelial cells and macrophages. The molecular mechanisms facilitating colonization and pathogenesis remain unclear. Given the importance of bacterial adhesion to host surfaces in microbial pathogenesis, we investigated the role of the O antigen LPS in the interaction of Burkholderia cenocepacia, a member of the Bcc, with macrophages and epithelial cells. Our results demonstrated that the O antigen modulates phagocytosis but does not affect intracellular survival of B. cenocepacia. Internalization of strains that lack O antigen was significantly increased compared to that of their isogenic smooth counterparts. However, no differences between rough and smooth strains were found in their ability to delay phagosomal maturation. We also found that the O antigen interfered with the ability of B. cenocepacia to adhere to bronchial epithelial cells, suggesting that this polysaccharide may mask one or more bacterial surface adhesins.
Collapse
Affiliation(s)
- M Soledad Saldías
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ximena Ortega
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Miguel A Valvano
- Department of Medicine, University of Western Ontario, London, Ontario N6A 5C1, Canada.,Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| |
Collapse
|
38
|
Phase variation has a role in Burkholderia ambifaria niche adaptation. ISME JOURNAL 2009; 4:49-60. [PMID: 19710710 DOI: 10.1038/ismej.2009.95] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Members of the Burkholderia cepacia complex (Bcc), such as B. ambifaria, are effective biocontrol strains, for instance, as plant growth-promoting bacteria; however, Bcc isolates can also cause severe respiratory infections in people suffering from cystic fibrosis (CF). No distinction is known between isolates from environmental and human origins, suggesting that the natural environment is a potential source of infectious Bcc species. While investigating the presence and role of phase variation in B. ambifaria HSJ1, an isolate recovered from a CF patient, we identified stable variants that arose spontaneously irrespective of the culture conditions. Phenotypic and proteomic approaches revealed that the transition from wild-type to variant types affects the expression of several putative virulence factors. By using four different infection models (Drosophila melanogaster, Galleria mellonella, macrophages and Dictyostelium discoideum), we showed that the wild-type was more virulent than the variant. It may be noted that the variant showed reduced replication in a human monocyte cell line when compared with the wild-type. On the other hand, the variant of isolate HSJ1 was more competitive in colonizing plant roots than the wild-type. Furthermore, we observed that only clinical B. ambifaria isolates generated phase variants, and that these variants showed the same phenotypes as observed with the HSJ1 variant. Finally, we determined that environmental B. ambifaria isolates showed traits that were characteristic of variants derived from clinical isolates. Our study therefore suggest that B. ambifaria uses phase variation to adapt to drastically different environments: the lung of patients with CF or the rhizosphere.
Collapse
|
39
|
Virulence and cellular interactions of Burkholderia multivorans in chronic granulomatous disease. Infect Immun 2009; 77:4337-44. [PMID: 19635825 DOI: 10.1128/iai.00259-09] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Chronic granulomatous disease (CGD) patients are susceptible to life-threatening infections by the Burkholderia cepacia complex. We used leukocytes from CGD and healthy donors and compared cell association, invasion, and cytokine induction by Burkholderia multivorans strains. A CGD isolate, CGD1, showed higher cell association than that of an environmental isolate, Env1, which correlated with cell entry. All B. multivorans strains associated significantly more with cells from CGD patients than with those from healthy donors. Similar findings were observed with another CGD pathogen, Serratia marcescens, but not with Escherichia coli. In a mouse model of CGD, strain CGD1 was virulent while Env1 was avirulent. B. multivorans organisms were found in the spleens of CGD1-infected mice at levels that were 1,000 times higher than those found in Env1-infected mice, which was coincident with higher levels of the proinflammatory cytokine interleukin-1beta. Taken together, these results may shed light on the unique susceptibility of CGD patients to specific pathogens.
Collapse
|
40
|
Abstract
Bacteria infect the respiratory tract early in the course of cystic fibrosis disease, often fail to be eradicated, and together with an aggressive host inflammatory response, are thought to be key players in the irreversible airway damage from which most patients ultimately die. Although incompletely understood, certain aspects of the cystic fibrosis airway itself appear to favor the development of chronic modes of survival, in particular biofilm formation; this and the development of antibiotic resistance following exposure to multiple antibiotic courses lead to chronic, persistent infection. In addition to the common cystic fibrosis pathogens, such as Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa, several newer species are becoming more common. Furthermore, new molecular techniques have led to the identification of multiple different organisms within respiratory secretions, many of which are not cultured with conventional tools. Future work should aim to develop clinically applicable methods to identify these and to determine which have the potential to impact pulmonary health. We outline the basic tenets of infection control and treatment.
Collapse
Affiliation(s)
- Jane C Davies
- Department of Gene Therapy, Imperial College, Emmanuel Kaye Building, Manresa Road, London SW3 6NP, United Kingdom.
| | | |
Collapse
|
41
|
Identification of specific and universal virulence factors in Burkholderia cenocepacia strains by using multiple infection hosts. Infect Immun 2009; 77:4102-10. [PMID: 19528212 DOI: 10.1128/iai.00398-09] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Over the past few decades, strains of the Burkholderia cepacia complex have emerged as important pathogens for patients suffering from cystic fibrosis. Identification of virulence factors and assessment of the pathogenic potential of Burkholderia strains have increased the need for appropriate infection models. In previous studies, different infection hosts, including mammals, nematodes, insects, and plants, have been used. At present, however, the extent to which the virulence factors required to infect different hosts overlap is not known. The aim of this study was to analyze the roles of various virulence factors of two closely related Burkholderia cenocepacia strains, H111 and the epidemic strain K56-2, in a multihost pathogenesis system using four different model organisms, namely, Caenorhabditis elegans, Galleria mellonella, the alfalfa plant, and mice or rats. We demonstrate that most of the identified virulence factors are specific for one of the infection models, and only three factors were found to be essential for full pathogenicity in several hosts: mutants defective in (i) quorum sensing, (ii) siderophore production, and (iii) lipopolysaccharide biosynthesis were attenuated in at least three of the infection models and thus may represent promising targets for the development of novel anti-infectives.
Collapse
|
42
|
Ortega X, Silipo A, Saldías MS, Bates CC, Molinaro A, Valvano MA. Biosynthesis and structure of the Burkholderia cenocepacia K56-2 lipopolysaccharide core oligosaccharide: truncation of the core oligosaccharide leads to increased binding and sensitivity to polymyxin B. J Biol Chem 2009; 284:21738-51. [PMID: 19525227 DOI: 10.1074/jbc.m109.008532] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen that displays a remarkably high resistance to antimicrobial peptides. We hypothesize that high resistance to antimicrobial peptides in these bacteria is because of the barrier properties of the outer membrane. Here we report the identification of genes for the biosynthesis of the core oligosaccharide (OS) moiety of the B. cenocepacia lipopolysaccharide. We constructed a panel of isogenic mutants with truncated core OS that facilitated functional gene assignments and the elucidation of the core OS structure in the prototypic strain K56-2. The core OS structure consists of three heptoses in the inner core region, 3-deoxy-d-manno-octulosonic acid, d-glycero-d-talo-octulosonic acid, and 4-amino-4-deoxy-l-arabinose linked to d-glycero-d-talo-octulosonic acid. Also, glucose is linked to heptose I, whereas heptose II carries a second glucose and a terminal heptose, which is the site of attachment of the O antigen. We established that the level of core truncation in the mutants was proportional to their increased in vitro sensitivity to polymyxin B (PmB). Binding assays using fluorescent 5-dimethylaminonaphthalene-1-sulfonyl-labeled PmB demonstrated a correlation between sensitivity and increased binding of PmB to intact cells. Also, the mutant producing a heptoseless core OS did not survive in macrophages as compared with the parental K56-2 strain. Together, our results demonstrate that a complete core OS is required for full PmB resistance in B. cenocepacia and that resistance is due, at least in part, to the ability of B. cenocepacia to prevent binding of the peptide to the bacterial cell envelope.
Collapse
Affiliation(s)
- Ximena Ortega
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | | | | | | | | | | |
Collapse
|
43
|
Keith KE, Hynes DW, Sholdice JE, Valvano MA. Delayed association of the NADPH oxidase complex with macrophage vacuoles containing the opportunistic pathogen Burkholderia cenocepacia. MICROBIOLOGY-SGM 2009; 155:1004-1015. [PMID: 19332803 DOI: 10.1099/mic.0.026781-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia cenocepacia causes chronic lung infections in patients suffering from cystic fibrosis and chronic granulomatous disease. We have previously shown that B. cenocepacia survives intracellularly in macrophages within a membrane vacuole (BcCV) that delays acidification. Here, we report that after macrophage infection with live B. cenocepacia there is a approximately 6 h delay in the association of NADPH oxidase with BcCVs, while heat-inactivated bacteria are normally trafficked into NADPH oxidase-positive vacuoles. BcCVs in macrophages treated with a functional inhibitor of the cystic fibrosis transmembrane conductance regulator exhibited a further delay in the assembly of the NADPH oxidase complex at the BcCV membrane, but the inhibitor did not affect NADPH oxidase complex assembly onto vacuoles containing heat-inactivated B. cenocepacia or live Escherichia coli. Macrophages produced less superoxide following B. cenocepacia infection as compared to heat-inactivated B. cenocepacia and E. coli controls. Reduced superoxide production was associated with delayed deposition of cerium perhydroxide precipitates around BcCVs of macrophages infected with live B. cenocepacia, as visualized by transmission electron microscopy. Together, our results demonstrate that intracellular B. cenocepacia resides in macrophage vacuoles displaying an altered recruitment of the NADPH oxidase complex at the phagosomal membrane. This phenomenon may contribute to preventing the efficient clearance of this opportunistic pathogen from the infected airways of susceptible patients.
Collapse
Affiliation(s)
- Karen E Keith
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Daniel W Hynes
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Judith E Sholdice
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Miguel A Valvano
- Department of Medicine, University of Western Ontario, London, ON N6A 5C1, Canada.,Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| |
Collapse
|
44
|
Burkholderia cenocepacia-induced delay of acidification and phagolysosomal fusion in cystic fibrosis transmembrane conductance regulator (CFTR)-defective macrophages. Microbiology (Reading) 2008; 154:3825-3834. [DOI: 10.1099/mic.0.2008/023200-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
45
|
The genome of Burkholderia cenocepacia J2315, an epidemic pathogen of cystic fibrosis patients. J Bacteriol 2008; 191:261-77. [PMID: 18931103 PMCID: PMC2612433 DOI: 10.1128/jb.01230-08] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Bacterial infections of the lungs of cystic fibrosis (CF) patients cause major complications in the treatment of this common genetic disease. Burkholderia cenocepacia infection is particularly problematic since this organism has high levels of antibiotic resistance, making it difficult to eradicate; the resulting chronic infections are associated with severe declines in lung function and increased mortality rates. B. cenocepacia strain J2315 was isolated from a CF patient and is a member of the epidemic ET12 lineage that originated in Canada or the United Kingdom and spread to Europe. The 8.06-Mb genome of this highly transmissible pathogen comprises three circular chromosomes and a plasmid and encodes a broad array of functions typical of this metabolically versatile genus, as well as numerous virulence and drug resistance functions. Although B. cenocepacia strains can be isolated from soil and can be pathogenic to both plants and man, J2315 is representative of a lineage of B. cenocepacia rarely isolated from the environment and which spreads between CF patients. Comparative analysis revealed that ca. 21% of the genome is unique in comparison to other strains of B. cenocepacia, highlighting the genomic plasticity of this species. Pseudogenes in virulence determinants suggest that the pathogenic response of J2315 may have been recently selected to promote persistence in the CF lung. The J2315 genome contains evidence that its unique and highly adapted genetic content has played a significant role in its success as an epidemic CF pathogen.
Collapse
|
46
|
MacDonald KL, Speert DP. Differential modulation of innate immune cell functions by theBurkholderia cepaciacomplex:Burkholderia cenocepaciabut notBurkholderia multivoransdisrupts maturation and induces necrosis in human dendritic cells. Cell Microbiol 2008; 10:2138-49. [DOI: 10.1111/j.1462-5822.2008.01197.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
|
47
|
CFTR mutations impart elevated immune reactivity in a murine model of cystic fibrosis related diabetes. Cytokine 2008; 44:154-9. [DOI: 10.1016/j.cyto.2008.07.468] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Revised: 04/11/2008] [Accepted: 07/17/2008] [Indexed: 11/21/2022]
|
48
|
A type IV secretion system contributes to intracellular survival and replication of Burkholderia cenocepacia. Infect Immun 2008; 76:5447-55. [PMID: 18824538 DOI: 10.1128/iai.00451-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Burkholderia cenocepacia is an important respiratory pathogen in persons with cystic fibrosis (CF). Recent studies indicate that B. cenocepacia survives within macrophages and airway epithelial cells in vitro by evading endosome-lysosome fusion. We investigated the role of a plasmid-encoded type IV secretion system in the intracellular survival, replication, and processing of B. cenocepacia. Both a wild-type strain (K56-2) and its type IV secretion system mutant (designated LC101) entered and replicated in CF airway epithelial cells and monocyte-derived macrophages. However, significantly more intracellular K56-2 than LC101 bacteria were found in both cell types at 24 h postinfection. Colocalization of bacteria with markers of the classical endocytic pathway indicated that although both K56-2 and LC101 reside transiently in early endosomes, a greater proportion of the mutant bacteria are targeted to lysosomal degradation. In contrast, wild-type bacteria escape from the classical endocytic pathway and traffic to the endoplasmic reticulum, where they replicate. Our results show that the intracellular processing of B. cenocepacia is similar in both professional and nonprofessional phagocytes and that a functional plasmid-encoded type IV secretion system contributes to the survival and replication of B. cenocepacia in eukaryotic cells.
Collapse
|
49
|
Flannagan RS, Valvano MA. Burkholderia cenocepacia requires RpoE for growth under stress conditions and delay of phagolysosomal fusion in macrophages. MICROBIOLOGY-SGM 2008; 154:643-653. [PMID: 18227267 DOI: 10.1099/mic.0.2007/013714-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Burkholderia cenocepacia is an opportunistic pathogen causing serious infections in patients with cystic fibrosis. The widespread distribution of this bacterium in the environment suggests that it must adapt to stress to be able to survive. We identified in B. cenocepacia K56-2 a gene predicted to encode RpoE, the extra-cytoplasmic stress response regulator. The rpoE gene is the first gene of a predicted operon encoding proteins homologous to RseA, RseB, MucD and a protein of unknown function. The genomic organization and the co-transcription of these genes were confirmed by PCR and RT-PCR. The mucD and rpoE genes were mutated, giving rise to B. cenocepacia RSF24 and RSF25, respectively. While mutant RSF24 did not demonstrate any growth defects under the conditions tested, RSF25 was compromised for growth under temperature (44 degrees C) and osmotic stress (426 mM NaCl). Expression of RpoE in trans could complement the osmotic growth defect but exacerbated temperature sensitivity in both RSF25 and wild-type K56-2. Inactivation of rpoE altered the bacterial cell surface, as indicated by increased binding of the fluorescent dye calcofluor white and by an altered outer-membrane protein profile. These cell surface changes were restored by complementation with a plasmid encoding rpoE. Macrophage infections in which bacterial colocalization with fluorescent dextran was examined demonstrated that the rpoE mutant could not delay the fusion of B. cenocepacia-containing vacuoles with lysosomes, in contrast to the parental strain K56-2. These data show that B. cenocepacia rpoE is required for bacterial growth under certain stress conditions and for the ability of intracellular bacteria to delay phagolysosomal fusion in macrophages.
Collapse
Affiliation(s)
- Ronald S Flannagan
- Infectious Disease Research Group, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Miguel A Valvano
- Medicine, Siebens-Drake Research Institute, University of Western Ontario, London, Ontario, Canada.,Infectious Disease Research Group, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
50
|
Salmanian AH, Siavoshi F, Akbari F, Afshari A, Malekzadeh R. Yeast of the oral cavity is the reservoir of Heliobacter pylori. J Oral Pathol Med 2008; 37:324-8. [PMID: 18266659 DOI: 10.1111/j.1600-0714.2007.00632.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Frequent occurrence of Helicobacter pylori in the human gastrointestinal tract and its persistence due to unsuccessful antimicrobial therapy might be related to a stage in the life cycle of H. pylori in which the bacterium establishes itself as an intracellular symbiont in yeast. In this study, occurrence of non-culturable H. pylori in the oral yeast was assessed by targeting vacuolating cytotoxin A (vacA s1s2) and ureAB genes in the total DNAs of yeasts. METHODS DNAs were extracted from 13 oral yeasts in which bacterium-like bodies, suspected to be H. pylori, were observed microscopically. Primers were recruited to amplify vacA s1s2 and ureAB genes. DNAs from H. pylori and E. coli were used as controls. The amplicons from one yeast and H. pylori were sequenced. Yeasts were identified as Candida albicans. RESULTS Fragments of vacA s1s2 and ureAB genes were amplified from 13 yeasts. The size of PCR products was 286 bp for vacA s1s2 gene and 406 bp for ureAB gene. Similar bands were obtained from the control H. pylori, and the results for E. coli were negative. The data from sequencing of PCR products showed about 98% homology between the genes amplified from yeast and those from H. pylori. CONCLUSIONS The results of this study showed the intracellular occurrence of H. pylori in yeast. This endosymbiotic relationship might explain the persistence of H. pylori in the oral cavity, the consequence of which could be reinoculation of the stomach by the bacterium and spread of infection among human populations.
Collapse
Affiliation(s)
- Ali-Hatef Salmanian
- Department of Plant Molecular Biology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran.
| | | | | | | | | |
Collapse
|