1
|
Aziz UBA, Saoud A, Bermudez M, Mieth M, Atef A, Rudolf T, Arkona C, Trenkner T, Böttcher C, Ludwig K, Hoelzemer A, Hocke AC, Wolber G, Rademann J. Targeted small molecule inhibitors blocking the cytolytic effects of pneumolysin and homologous toxins. Nat Commun 2024; 15:3537. [PMID: 38670939 PMCID: PMC11053136 DOI: 10.1038/s41467-024-47741-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Pneumolysin (PLY) is a cholesterol-dependent cytolysin (CDC) from Streptococcus pneumoniae, the main cause for bacterial pneumonia. Liberation of PLY during infection leads to compromised immune system and cytolytic cell death. Here, we report discovery, development, and validation of targeted small molecule inhibitors of PLY (pore-blockers, PB). PB-1 is a virtual screening hit inhibiting PLY-mediated hemolysis. Structural optimization provides PB-2 with improved efficacy. Cryo-electron tomography reveals that PB-2 blocks PLY-binding to cholesterol-containing membranes and subsequent pore formation. Scaffold-hopping delivers PB-3 with superior chemical stability and solubility. PB-3, formed in a protein-templated reaction, binds to Cys428 adjacent to the cholesterol recognition domain of PLY with a KD of 256 nM and a residence time of 2000 s. It acts as anti-virulence factor preventing human lung epithelial cells from PLY-mediated cytolysis and cell death during infection with Streptococcus pneumoniae and is active against the homologous Cys-containing CDC perfringolysin (PFO) as well.
Collapse
Affiliation(s)
- Umer Bin Abdul Aziz
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
| | - Ali Saoud
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
| | - Marcel Bermudez
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
- Institute for Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstr. 48, 48149, Münster, Germany
| | - Maren Mieth
- Department of Infectious Diseases, Respiratory Medicine, and Critical Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Amira Atef
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
- Department of Medicinal Chemistry, Faculty of Pharmacy, Assuit University, Assiut, 71526, Egypt
| | - Thomas Rudolf
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
| | - Christoph Arkona
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
| | - Timo Trenkner
- Leibniz Institute of Virology, Hamburg, 20251, Germany
| | - Christoph Böttcher
- Institute of Chemistry and Biochemistry, Research Center of Electron Microscopy (FZEM), Freie Universität Berlin, Fabeckstraße 36A, 14195, Berlin, Germany
| | - Kai Ludwig
- Institute of Chemistry and Biochemistry, Research Center of Electron Microscopy (FZEM), Freie Universität Berlin, Fabeckstraße 36A, 14195, Berlin, Germany
| | - Angelique Hoelzemer
- Leibniz Institute of Virology, Hamburg, 20251, Germany
- First Department of Medicine, University Medical Center Hamburg-Eppendorf (UKE), 20251, Hamburg, Germany
| | - Andreas C Hocke
- Department of Infectious Diseases, Respiratory Medicine, and Critical Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Gerhard Wolber
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
| | - Jörg Rademann
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany.
| |
Collapse
|
2
|
Kruckow KL, Zhao K, Bowdish DME, Orihuela CJ. Acute organ injury and long-term sequelae of severe pneumococcal infections. Pneumonia (Nathan) 2023; 15:5. [PMID: 36870980 PMCID: PMC9985869 DOI: 10.1186/s41479-023-00110-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 01/31/2023] [Indexed: 03/06/2023] Open
Abstract
Streptococcus pneumoniae (Spn) is a major public health problem, as it is a main cause of otitis media, community-acquired pneumonia, bacteremia, sepsis, and meningitis. Acute episodes of pneumococcal disease have been demonstrated to cause organ damage with lingering negative consequences. Cytotoxic products released by the bacterium, biomechanical and physiological stress resulting from infection, and the corresponding inflammatory response together contribute to organ damage accrued during infection. The collective result of this damage can be acutely life-threatening, but among survivors, it also contributes to the long-lasting sequelae of pneumococcal disease. These include the development of new morbidities or exacerbation of pre-existing conditions such as COPD, heart disease, and neurological impairments. Currently, pneumonia is ranked as the 9th leading cause of death, but this estimate only considers short-term mortality and likely underestimates the true long-term impact of disease. Herein, we review the data that indicates damage incurred during acute pneumococcal infection can result in long-term sequelae which reduces quality of life and life expectancy among pneumococcal disease survivors.
Collapse
Affiliation(s)
- Katherine L Kruckow
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kevin Zhao
- McMaster Immunology Research Centre and the Firestone Institute for Respiratory Health, McMaster University, Hamilton, Canada
| | - Dawn M E Bowdish
- McMaster Immunology Research Centre and the Firestone Institute for Respiratory Health, McMaster University, Hamilton, Canada
| | - Carlos J Orihuela
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
| |
Collapse
|
3
|
Barron SL, Saez J, Owens RM. In Vitro Models for Studying Respiratory Host-Pathogen Interactions. Adv Biol (Weinh) 2021; 5:e2000624. [PMID: 33943040 PMCID: PMC8212094 DOI: 10.1002/adbi.202000624] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/23/2021] [Indexed: 12/22/2022]
Abstract
Respiratory diseases and lower respiratory tract infections are among the leading cause of death worldwide and, especially given the recent severe acute respiratory syndrome coronavirus-2 pandemic, are of high and prevalent socio-economic importance. In vitro models, which accurately represent the lung microenvironment, are of increasing significance given the ethical concerns around animal work and the lack of translation to human disease, as well as the lengthy time to market and the attrition rates associated with clinical trials. This review gives an overview of the biological and immunological components involved in regulating the respiratory epithelium system in health, disease, and infection. The evolution from 2D to 3D cell biology and to more advanced technological integrated models for studying respiratory host-pathogen interactions are reviewed and provide a reference point for understanding the in vitro modeling requirements. Finally, the current limitations and future perspectives for advancing this field are presented.
Collapse
Affiliation(s)
- Sarah L. Barron
- Bioassay Impurities and QualityBiopharmaceuticals DevelopmentR&DAstraZenecaCambridgeCB21 6GPUK
- Department of Chemical Engineering and BiotechnologyPhilippa Fawcett DriveCambridgeCB3 0ASUK
| | - Janire Saez
- Department of Chemical Engineering and BiotechnologyPhilippa Fawcett DriveCambridgeCB3 0ASUK
| | - Róisín M. Owens
- Department of Chemical Engineering and BiotechnologyPhilippa Fawcett DriveCambridgeCB3 0ASUK
| |
Collapse
|
4
|
Morimura A, Hamaguchi S, Akeda Y, Tomono K. Mechanisms Underlying Pneumococcal Transmission and Factors Influencing Host-Pneumococcus Interaction: A Review. Front Cell Infect Microbiol 2021; 11:639450. [PMID: 33996623 PMCID: PMC8113816 DOI: 10.3389/fcimb.2021.639450] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/06/2021] [Indexed: 01/21/2023] Open
Abstract
Streptococcus pneumoniae (also called pneumococcus) is not only a commensal that frequently colonizes the human upper respiratory tract but also a pathogen that causes pneumonia, sepsis, and meningitis. The mechanism of pneumococcal infection has been extensively studied, but the process of transmission has not been fully elucidated because of the lack of tractable animal models. Novel animal models of transmission have enabled further progress in investigating pneumococcal transmission mechanisms including the processes such as pneumococcal shedding, survival in the external environment, and adherence to the nasopharynx of a new host. Herein, we present a review on these animal models, recent research findings about pneumococcal transmission, and factors influencing the host-pneumococcus interaction.
Collapse
Affiliation(s)
- Ayumi Morimura
- Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Shigeto Hamaguchi
- Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, Osaka, Japan.,Division of Infection Control and Prevention, Osaka University Hospital, Osaka, Japan
| | - Yukihiro Akeda
- Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, Osaka, Japan.,Division of Infection Control and Prevention, Osaka University Hospital, Osaka, Japan.,Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Kazunori Tomono
- Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, Osaka, Japan.,Division of Infection Control and Prevention, Osaka University Hospital, Osaka, Japan
| |
Collapse
|
5
|
The Role of Age, Neutrophil Infiltration and Antibiotics Timing in the Severity of Streptococcus pneumoniae Pneumonia. Insights from a Multi-Level Mathematical Model Approach. Int J Mol Sci 2020; 21:ijms21228428. [PMID: 33182614 PMCID: PMC7696447 DOI: 10.3390/ijms21228428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/06/2020] [Accepted: 11/08/2020] [Indexed: 12/11/2022] Open
Abstract
Bacterial pneumonia is one of the most prevalent infectious diseases and has high mortality in sensitive patients (children, elderly and immunocompromised). Although an infection, the disease alters the alveolar epithelium homeostasis and hinders normal breathing, often with fatal consequences. A special case is hospitalized aged patients, which present a high risk of infection and death because of the community acquired version of the Streptococcus pneumoniae pneumonia. There is evidence that early antibiotics treatment decreases the inflammatory response during pneumonia. Here, we investigate mechanistically this strategy using a multi-level mathematical model, which describes the 24 first hours after infection of a single alveolus from the key signaling networks behind activation of the epithelium to the dynamics of the local immune response. With the model, we simulated pneumonia in aged and young patients subjected to different antibiotics timing. The results show that providing antibiotics to elderly patients 8 h in advance compared to young patients restores in aged individuals the effective response seen in young ones. This result suggests the use of early, probably prophylactic, antibiotics treatment in aged hospitalized people with high risk of pneumonia.
Collapse
|
6
|
Iwahashi J, Kamei K, Watanabe H. Disruption of Aspergillus fumigatus biofilm by Streptococcus pneumoniae: Mycelial fragmentation by hydrogen peroxide. J Infect Chemother 2020; 26:831-837. [PMID: 32414689 DOI: 10.1016/j.jiac.2020.03.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/07/2020] [Accepted: 03/24/2020] [Indexed: 01/06/2023]
Abstract
Biofilm is a complex structure consisting of microorganisms such as bacteria, fungi and an extracellular matrix (ECM). Biofilms are involved in most microbial infections and show persistent resistance to antibiotic treatment and immune response. Both Aspergillus fumigatus and Streptococcus pneumoniae are colonizers that can form biofilms in the respiratory tract. These pathogens have been simultaneously isolated from the same patient, but their interaction is poorly understood. We observed morphological changes in single- and mixed-species biofilms prepared for confocal laser scanning microscopy and scanning electron microscopy (SEM). Pneumococci suppressed the development of a fungal biofilm, and it even disrupted a preformed fungal biofilm. When a preformed fungal biofilm was treated with pneumococci, the mycelial network was fragmented, and only bacteria could develop. SEM revealed that the fragmented mycelium was further disrupted into fine filaments as treatment time progressed, and that the ECM of the preformed fungal biofilm had disappeared. The pneumococcal culture supernatant contained mycelial fragmentation activity that was heat-sensitive. The culture supernatant of a mutant pneumococcal strain deficient in pneumolysin (Δply) also exhibited the mycelial fragmentation activity. Enolase and lactate oxidase, which are involved in glycolysis and hydrogen peroxide production, were identified in the culture supernatant of the Δply mutant. Neither the wild type nor the mutant strain could fragment the mycelium in the presence of catalase. These data suggest that hydrogen peroxide could fragment the mycelium and would terminate the co-existence of A. fumigatus and S. pneumoniae in biofilm.
Collapse
Affiliation(s)
- Jun Iwahashi
- Department of Infection Control and Prevention, Kurume University School of Medicine, 67 Asahi-machi, Kurume City, Fukuoka 830-0011, Japan.
| | - Katsuhiko Kamei
- Division of Clinical Research, Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba 260-8673, Japan
| | - Hiroshi Watanabe
- Department of Infection Control and Prevention, Kurume University School of Medicine, 67 Asahi-machi, Kurume City, Fukuoka 830-0011, Japan
| |
Collapse
|
7
|
Lucas R, Hadizamani Y, Gonzales J, Gorshkov B, Bodmer T, Berthiaume Y, Moehrlen U, Lode H, Huwer H, Hudel M, Mraheil MA, Toque HAF, Chakraborty T, Hamacher J. Impact of Bacterial Toxins in the Lungs. Toxins (Basel) 2020; 12:toxins12040223. [PMID: 32252376 PMCID: PMC7232160 DOI: 10.3390/toxins12040223] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
Bacterial toxins play a key role in the pathogenesis of lung disease. Based on their structural and functional properties, they employ various strategies to modulate lung barrier function and to impair host defense in order to promote infection. Although in general, these toxins target common cellular signaling pathways and host compartments, toxin- and cell-specific effects have also been reported. Toxins can affect resident pulmonary cells involved in alveolar fluid clearance (AFC) and barrier function through impairing vectorial Na+ transport and through cytoskeletal collapse, as such, destroying cell-cell adhesions. The resulting loss of alveolar-capillary barrier integrity and fluid clearance capacity will induce capillary leak and foster edema formation, which will in turn impair gas exchange and endanger the survival of the host. Toxins modulate or neutralize protective host cell mechanisms of both the innate and adaptive immunity response during chronic infection. In particular, toxins can either recruit or kill central players of the lung's innate immune responses to pathogenic attacks, i.e., alveolar macrophages (AMs) and neutrophils. Pulmonary disorders resulting from these toxin actions include, e.g., acute lung injury (ALI), the acute respiratory syndrome (ARDS), and severe pneumonia. When acute infection converts to persistence, i.e., colonization and chronic infection, lung diseases, such as bronchitis, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) can arise. The aim of this review is to discuss the impact of bacterial toxins in the lungs and the resulting outcomes for pathogenesis, their roles in promoting bacterial dissemination, and bacterial survival in disease progression.
Collapse
Affiliation(s)
- Rudolf Lucas
- Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Department of Medicine and Division of Pulmonary Critical Care Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Correspondence: (R.L.); (J.H.); Tel.: +41-31-300-35-00 (J.H.)
| | - Yalda Hadizamani
- Lungen-und Atmungsstiftung, Bern, 3012 Bern, Switzerland;
- Pneumology, Clinic for General Internal Medicine, Lindenhofspital Bern, 3012 Bern, Switzerland
| | - Joyce Gonzales
- Department of Medicine and Division of Pulmonary Critical Care Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
| | - Boris Gorshkov
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
| | - Thomas Bodmer
- Labormedizinisches Zentrum Dr. Risch, Waldeggstr. 37 CH-3097 Liebefeld, Switzerland;
| | - Yves Berthiaume
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada;
| | - Ueli Moehrlen
- Pediatric Surgery, University Children’s Hospital, Zürich, Steinwiesstrasse 75, CH-8032 Zürch, Switzerland;
| | - Hartmut Lode
- Insitut für klinische Pharmakologie, Charité, Universitätsklinikum Berlin, Reichsstrasse 2, D-14052 Berlin, Germany;
| | - Hanno Huwer
- Department of Cardiothoracic Surgery, Voelklingen Heart Center, 66333 Voelklingen/Saar, Germany;
| | - Martina Hudel
- Justus-Liebig-University, Biomedical Research Centre Seltersberg, Schubertstr. 81, 35392 Giessen, Germany; (M.H.); (M.A.M.); (T.C.)
| | - Mobarak Abu Mraheil
- Justus-Liebig-University, Biomedical Research Centre Seltersberg, Schubertstr. 81, 35392 Giessen, Germany; (M.H.); (M.A.M.); (T.C.)
| | - Haroldo Alfredo Flores Toque
- Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
| | - Trinad Chakraborty
- Justus-Liebig-University, Biomedical Research Centre Seltersberg, Schubertstr. 81, 35392 Giessen, Germany; (M.H.); (M.A.M.); (T.C.)
| | - Jürg Hamacher
- Lungen-und Atmungsstiftung, Bern, 3012 Bern, Switzerland;
- Pneumology, Clinic for General Internal Medicine, Lindenhofspital Bern, 3012 Bern, Switzerland
- Medical Clinic V-Pneumology, Allergology, Intensive Care Medicine and Environmental Medicine, Faculty of Medicine, Saarland University, University Medical Centre of the Saarland, D-66421 Homburg, Germany
- Institute for Clinical & Experimental Surgery, Faculty of Medicine, Saarland University, D-66421 Homburg, Germany
- Correspondence: (R.L.); (J.H.); Tel.: +41-31-300-35-00 (J.H.)
| |
Collapse
|
8
|
Anderson R, Feldman C. Pneumolysin as a potential therapeutic target in severe pneumococcal disease. J Infect 2017; 74:527-544. [PMID: 28322888 DOI: 10.1016/j.jinf.2017.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/09/2017] [Accepted: 03/11/2017] [Indexed: 12/13/2022]
Abstract
Acute pulmonary and cardiac injury remain significant causes of morbidity and mortality in those afflicted with severe pneumococcal disease, with the risk for early mortality often persisting several years beyond clinical recovery. Although remaining to be firmly established in the clinical setting, a considerable body of evidence, mostly derived from murine models of experimental infection, has implicated the pneumococcal, cholesterol-binding, pore-forming toxin, pneumolysin (Ply), in the pathogenesis of lung and myocardial dysfunction. Topics covered in this review include the burden of pneumococcal disease, risk factors, virulence determinants of the pneumococcus, complications of severe disease, antibiotic and adjuvant therapies, as well as the structure of Ply and the role of the toxin in disease pathogenesis. Given the increasing recognition of the clinical potential of Ply-neutralisation strategies, the remaining sections of the review are focused on updates of the types, benefits and limitations of currently available therapies which may attenuate, directly and/or indirectly, the injurious actions of Ply. These include recently described experimental therapies such as various phytochemicals and lipids, and a second group of more conventional agents the members of which remain the subject of ongoing clinical evaluation. This latter group, which is covered more extensively, encompasses macrolides, statins, corticosteroids, and platelet-targeted therapies, particularly aspirin.
Collapse
Affiliation(s)
- Ronald Anderson
- Department of Immunology and Institute of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
| | - Charles Feldman
- Division of Pulmonology, Department of Internal Medicine, Charlotte Maxeke Johannesburg Academic Hospital and Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| |
Collapse
|
9
|
Nel JG, Durandt C, Theron AJ, Tintinger GR, Pool R, Richards GA, Mitchell TJ, Feldman C, Anderson R. Pneumolysin mediates heterotypic aggregation of neutrophils and platelets in vitro. J Infect 2017; 74:599-608. [PMID: 28267572 DOI: 10.1016/j.jinf.2017.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/17/2017] [Accepted: 02/24/2017] [Indexed: 10/20/2022]
Abstract
OBJECTIVES Platelets orchestrate the inflammatory activities of neutrophils, possibly contributing to pulmonary and myocardial damage during severe pneumococcal infection. This study tested the hypothesis that the pneumococcal toxin, pneumolysin (Ply), activates production of platelet-activating factor (PAF) and thromboxane A2 (TxA2) by neutrophils, these bioactive lipids being potential mediators of neutrophil:platelet (NP) networking. METHODS The effects of recombinant Ply (10-80 ng mL-1) on the production of PAF and TxA2 by isolated neutrophils were measured using ELISA procedures, and NP aggregation by flow cytometry. RESULTS Exposure of neutrophils to Ply induced production of PAF and, to a lesser extent, TxA2, achieving statistical significance at ≥20 ng mL-1 of the toxin. In the case of NP interactions, Ply promoted heterotypic aggregation which was dependent on upregulation of P-selectin (CD62P) and activation of protease-activated receptor 1 (PAR1), attaining statistical significance at ≥10 ng mL-1 of the toxin, but did not involve either PAF or TxA2. CONCLUSION Ply induces synthesis of PAF and TxA2, by human neutrophils, neither of which appears to contribute to the formation of NP heterotypic aggregates in vitro, a process which is seemingly dependent on CD62P and PAR1. These pro-inflammatory activities of Ply may contribute to the pathogenesis of pulmonary and myocardial injury during severe pneumococcal infection.
Collapse
Affiliation(s)
- Jan G Nel
- Department of Haematology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; Tshwane Academic Division of the National Health Laboratory Service, Pretoria, South Africa.
| | - Chrisna Durandt
- Institute for Cellular and Molecular Medicine, South African Medical Research Council Unit for Stem Cell Research, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Annette J Theron
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Gregory R Tintinger
- Department of Internal Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Roger Pool
- Department of Haematology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; Tshwane Academic Division of the National Health Laboratory Service, Pretoria, South Africa
| | - Guy A Richards
- Department of Critical Care, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Timothy J Mitchell
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Charles Feldman
- Division of Pulmonology, Department of Internal Medicine, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa
| | - Ronald Anderson
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; Institute for Cellular and Molecular Medicine, South African Medical Research Council Unit for Stem Cell Research, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| |
Collapse
|
10
|
Prager O, Friedman A, Nebenzahl YM. Role of neural barriers in the pathogenesis and outcome of Streptococcus pneumoniae meningitis. Exp Ther Med 2017; 13:799-809. [PMID: 28450902 PMCID: PMC5403536 DOI: 10.3892/etm.2017.4082] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/10/2016] [Indexed: 12/20/2022] Open
Abstract
Bacterial meningitis is an inflammatory disease of the meninges of the central nervous system (CNS). Streptococcus pneumoniae (S. pneumoniae), Neisseria meningitidis, and Haemophilus influenzae are the major bacterial pathogens causing meningitis with S. pneumoniae being responsible for two thirds of meningitis cases in the developed world. To reach the CNS following nasopharyngeal colonization and bacteraemia, the bacteria traverse from the circulation across the blood brain barrier (BBB) and choroid plexus. While the BBB has a protective role in healthy individuals by shielding the CNS from neurotoxic substances circulating in the blood and maintaining the homeostasis within the brain environment, dysfunction of the BBB is associated with the pathophysiology of numerous neurologic disorders, including bacterial meningitis. Inflammatory processes, including release of a broad range of cytokines and free radicals, further increase vascular permeability and contribute to the excessive neural damage observed. Injury to the cerebral microvasculature and loss of blood flow auto-regulation promote increased intracranial pressure and may lead to vascular occlusion. Other common complications commonly associated with meningitis include abnormal neuronal hyper-excitability (e.g., seizures) and loss of hearing. Despite the existence of antibiotic treatment and adjuvant therapy, the relatively high mortality rate and the severe outcomes among survivors of pneumococcal meningitis in developing and developed countries increase the urgency in the requirement of discovering novel biomarkers for the early diagnosis as well as novel treatment approaches. The present review aimed to explore the changes in the brain vascular barriers, which allow S. pneumoniae to invade the CNS, and describe the resultant brain injuries following bacterial meningitis.
Collapse
Affiliation(s)
- Ofer Prager
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of The Negev, Beer-Sheva 84101, Israel.,Cognitive & Brain Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of The Negev, Beer-Sheva 84105, Israel
| | - Alon Friedman
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of The Negev, Beer-Sheva 84101, Israel.,Cognitive & Brain Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of The Negev, Beer-Sheva 84105, Israel.,Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Yaffa Mizrachi Nebenzahl
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of The Negev, Beer-Sheva 84101, Israel
| |
Collapse
|
11
|
Tenenbaum T, Asmat TM, Seitz M, Schroten H, Schwerk C. Biological activities of suilysin: role in Streptococcus suis pathogenesis. Future Microbiol 2016; 11:941-54. [PMID: 27357518 DOI: 10.2217/fmb-2016-0028] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Streptococcus suis is an important swine and zoonotic pathogen equipped with several virulence factors. The pore-forming toxins are the most abundant bacterial toxins and classified as critical virulence (associated) factors of several pathogens. The role of suilysin (SLY), a pore-forming cholesterol-dependent cytolysin of S. suis, as a true virulence factor is under debate. Most of the bacterial toxins have been reported to modulate the host immune system to facilitate invasion and subsequent replication of bacteria within respective host cells. SLY has been demonstrated to play an important role in the pathogenesis of S. suis infection and inflammatory response in vitro and in vivo. This review highlights the contributions of SLY to the pathogenicity of S. suis. It will address its role during the development of S. suis meningitis in pigs, as well as humans, and discuss SLY as a potential vaccine candidate.
Collapse
Affiliation(s)
- Tobias Tenenbaum
- Pediatric Infectious Diseases, Department of Pediatrics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim D-68167, Germany
| | - Tauseef M Asmat
- Center for Advanced Studies in Vaccinology and Biotechnology, Brewery Road, University of Balochistan, 87300 Quetta, Pakistan
| | - Maren Seitz
- Institute for Microbiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, Hannover D-30173, Germany
| | - Horst Schroten
- Pediatric Infectious Diseases, Department of Pediatrics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim D-68167, Germany
| | - Christian Schwerk
- Pediatric Infectious Diseases, Department of Pediatrics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim D-68167, Germany
| |
Collapse
|
12
|
Babiychuk EB, Draeger A. Defying death: Cellular survival strategies following plasmalemmal injury by bacterial toxins. Semin Cell Dev Biol 2015; 45:39-47. [PMID: 26481974 DOI: 10.1016/j.semcdb.2015.10.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/12/2015] [Indexed: 10/22/2022]
Abstract
The perforation of the plasmalemma by pore-forming toxins causes an influx of Ca(2+) and an efflux of cytoplasmic constituents. In order to ensure survival, the cell needs to identify, plug and remove lesions from its membrane. Quarantined by membrane folds and isolated by membrane fusion, the pores are removed from the plasmalemma and expelled into the extracellular space. Outward vesiculation and microparticle shedding seem to be the strategies of choice to eliminate toxin-perforated membrane regions from the plasmalemma of host cells. Depending on the cell type and the nature of injury, the membrane lesion can also be taken up by endocytosis and degraded internally. Host cells make excellent use of an initial, moderate rise in intracellular [Ca(2+)], which triggers containment of the toxin-inflicted damage and resealing of the damaged plasmalemma. Additional Ca(2+)-dependent defensive cellular actions range from the release of effector molecules in order to warn neighbouring cells, to the activation of caspases for the initiation of apoptosis in order to eliminate heavily damaged, dysregulated cells. Injury to the plasmalemma by bacterial toxins can be prevented by the early sequestration of bacterial toxins. Artificial liposomes can act as a decoy system preferentially binding and neutralizing bacterial toxins.
Collapse
|
13
|
Kim JA, Park JH, Lee MA, Lee HJ, Park SJ, Kim KS, Choi SH, Lee KH. Stationary-phase induction of vvpS expression by three transcription factors: repression by LeuO and activation by SmcR and CRP. Mol Microbiol 2015; 97:330-46. [PMID: 25869813 DOI: 10.1111/mmi.13028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2015] [Indexed: 11/27/2022]
Abstract
An exoprotease of Vibrio vulnificus, VvpS, exhibits an autolytic function during the stationary phase. To understand how vvpS expression is controlled, the regulators involved in vvpS transcription and their regulatory mechanisms were investigated. LeuO was isolated in a ligand-fishing experiment, and experiments using a leuO-deletion mutant revealed that LeuO represses vvpS transcription. LeuO bound the extended region including LeuO-binding site (LBS)-I and LBS-II. Further screening of additional regulators revealed that SmcR and cyclic adenosine monophosphate-receptor protein (CRP) play activating roles in vvpS transcription. SmcR and CRP bound the regions overlapping LBS-I and -II, respectively. In addition, the LeuO occupancy of LBS-I and LBS-II was competitively exchanged by SmcR and CRP, respectively. To examine the mechanism of stationary-phase induction of vvpS expression, in vivo levels of three transcription factors were monitored. Cellular level of LeuO was maximal at exponential phase, while those of SmcR and CRP were maximal at stationary phase and relatively constant after the early-exponential phase, respectively. Thus, vvpS transcription was not induced during the exponential phase by high cellular content of LeuO. When entering the stationary phase, however, LeuO content was significantly reduced and repression by LeuO was relieved through simultaneous binding of SmcR and CRP to LBS-I and -II, respectively.
Collapse
Affiliation(s)
- Jeong-A Kim
- Department of Life Science, Sogang University, Seoul, 121-742, South Korea
| | - Jin Hwan Park
- National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Seoul National University, Seoul, 151-921, South Korea
| | - Mi-Ae Lee
- Department of Life Science, Sogang University, Seoul, 121-742, South Korea
| | - Hyun-Jung Lee
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, 120-752, South Korea
| | - Soon-Jung Park
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, 120-752, South Korea
| | - Kun-Soo Kim
- Department of Life Science, Sogang University, Seoul, 121-742, South Korea
| | - Sang-Ho Choi
- National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Seoul National University, Seoul, 151-921, South Korea
| | - Kyu-Ho Lee
- Department of Life Science, Sogang University, Seoul, 121-742, South Korea
| |
Collapse
|
14
|
Abstract
Cholesterol dependent cytolysins are important in the ability of some bacteria to cause disease in man and animals. Pneumolysin (PLY) plays a key role in the diseases caused by Streptococcus pneumoniae (the pneumococcus). This chapter describes the role of PLY in some of the key process in disease. These include induction of cell death by pore formation and toxin-induced apoptosis as well as more subtle effects on gene expression of host cells including epigenetic effects of the toxin. The use of bacterial mutants that either do not express the toxin or express altered versions in biological systems is described. Use of isolated tissue and whole animal systems to dissect the structure/function relationships of the toxin as well as the role played by different activities in the pathogenesis of infection are described. The role of PLY in meningitis and the associated deafness is discussed as well as the role of the toxin in promoting increased lung permeability and inflammation during pneumococcal pneumonia. Different clinical strains of the pneumococcus produce different forms of PLY and the impact of this on disease caused by these strains is discussed. Finally, the impact of this knowledge on the development of treatment and prevention strategies for pneumococcal disease is discussed.
Collapse
|
15
|
Ali YM, Kenawy HI, Muhammad A, Sim RB, Andrew PW, Schwaeble WJ. Human L-ficolin, a recognition molecule of the lectin activation pathway of complement, activates complement by binding to pneumolysin, the major toxin of Streptococcus pneumoniae. PLoS One 2013; 8:e82583. [PMID: 24349316 PMCID: PMC3861440 DOI: 10.1371/journal.pone.0082583] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 11/04/2013] [Indexed: 01/04/2023] Open
Abstract
The complement system is an essential component of the immune response, providing a critical line of defense against different pathogens including S. pneumoniae. Complement is activated via three distinct pathways: the classical (CP), the alternative (AP) and the lectin pathway (LP). The role of Pneumolysin (PLY), a bacterial toxin released by S. pneumoniae, in triggering complement activation has been studied in vitro. Our results demonstrate that in both human and mouse sera complement was activated via the CP, initiated by direct binding of even non-specific IgM and IgG3 to PLY. Absence of CP activity in C1q(-/-) mouse serum completely abolished any C3 deposition. However, C1q depleted human serum strongly opsonized PLY through abundant deposition of C3 activation products, indicating that the LP may have a vital role in activating the human complement system on PLY. We identified that human L-ficolin is the critical LP recognition molecule that drives LP activation on PLY, while all of the murine LP recognition components fail to bind and activate complement on PLY. This work elucidates the detailed interactions between PLY and complement and shows for the first time a specific role of the LP in PLY-mediated complement activation in human serum.
Collapse
Affiliation(s)
- Youssif M. Ali
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
- Department of Microbiology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Hany I. Kenawy
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
- Department of Microbiology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Adnan Muhammad
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
| | - Robert B. Sim
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
| | - Peter W. Andrew
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
| | - Wilhelm J. Schwaeble
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
| |
Collapse
|
16
|
Seitz M, Baums C, Neis C, Benga L, Fulde M, Rohde M, Goethe R, Valentin-Weigand P. Subcytolytic effects of suilysin on interaction of Streptococcus suis with epithelial cells. Vet Microbiol 2013; 167:584-91. [DOI: 10.1016/j.vetmic.2013.09.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/26/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
|
17
|
Fliegauf M, Sonnen AFP, Kremer B, Henneke P. Mucociliary clearance defects in a murine in vitro model of pneumococcal airway infection. PLoS One 2013; 8:e59925. [PMID: 23527286 PMCID: PMC3602288 DOI: 10.1371/journal.pone.0059925] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 02/19/2013] [Indexed: 12/11/2022] Open
Abstract
Mucociliary airway clearance is an innate defense mechanism that protects the lung from harmful effects of inhaled pathogens. In order to escape mechanical clearance, airway pathogens including Streptococcus pneumoniae (pneumococcus) are thought to inactivate mucociliary clearance by mechanisms such as slowing of ciliary beating and lytic damage of epithelial cells. Pore-forming toxins like pneumolysin, may be instrumental in these processes. In a murine in vitro airway infection model using tracheal epithelial cells grown in air-liquid interface cultures, we investigated the functional consequences on the ciliated respiratory epithelium when the first contact with pneumococci is established. High-speed video microscopy and live-cell imaging showed that the apical infection with both wildtype and pneumolysin-deficient pneumococci caused insufficient fluid flow along the epithelial surface and loss of efficient clearance, whereas ciliary beat frequency remained within the normal range. Three-dimensional confocal microscopy demonstrated that pneumococci caused specific morphologic aberrations of two key elements in the F-actin cytoskeleton: the junctional F-actin at the apical cortex of the lateral cell borders and the apical F-actin, localized within the planes of the apical cell sides at the ciliary bases. The lesions affected the columnar shape of the polarized respiratory epithelial cells. In addition, the planar architecture of the entire ciliated respiratory epithelium was irregularly distorted. Our observations indicate that the mechanical supports essential for both effective cilia strokes and stability of the epithelial barrier were weakened. We provide a new model, where - in pneumococcal infection - persistent ciliary beating generates turbulent fluid flow at non-planar distorted epithelial surface areas, which enables pneumococci to resist mechanical cilia-mediated clearance.
Collapse
Affiliation(s)
- Manfred Fliegauf
- Centre of Chronic Immunodeficiency, University Medical Centre Freiburg and University of Freiburg, Freiburg, Germany.
| | | | | | | |
Collapse
|
18
|
Barichello T, Generoso JS, Collodel A, Moreira AP, Almeida SMD. Pathophysiology of acute meningitis caused by Streptococcus pneumoniae and adjunctive therapy approaches. ARQUIVOS DE NEURO-PSIQUIATRIA 2012; 70:366-72. [PMID: 22618789 DOI: 10.1590/s0004-282x2012000500011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/12/2012] [Indexed: 11/22/2022]
Abstract
Pneumococcal meningitis is a life-threatening disease characterized by an acute purulent infection affecting piamater, arachnoid and the subarachnoid space. The intense inflammatory host's response is potentially fatal and contributes to the neurological sequelae. Streptococcus pneumoniae colonizes the nasopharynx, followed by bacteremia, microbial invasion and blood-brain barrier traversal. S. pneumoniae is recognized by antigen-presenting cells through the binding of Toll-like receptors inducing the activation of factor nuclear kappa B or mitogen-activated protein kinase pathways and subsequent up-regulation of lymphocyte populations and expression of numerous proteins involved in inflammation and immune response. Many brain cells can produce cytokines, chemokines and others pro-inflammatory molecules in response to bacteria stimuli, as consequence, polymorphonuclear are attracted, activated and released in large amounts of superoxide anion and nitric oxide, leading to the peroxynitrite formation, generating oxidative stress. This cascade leads to lipid peroxidation, mitochondrial damage, blood-brain barrier breakdown contributing to cell injury during pneumococcal meningitis.
Collapse
Affiliation(s)
- Tatiana Barichello
- Laboratório de Microbiologia Experimental, Instituto Nacional de Ciência e Tecnologia Translacional em Medicina, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil.
| | | | | | | | | |
Collapse
|
19
|
Norcross EW, Sanders ME, Moore QC, Taylor SD, Tullos NA, Caston RR, Dixon SN, Nahm MH, Burton RL, Thompson H, McDaniel LS, Marquart ME. Active Immunization with Pneumolysin versus 23-Valent Polysaccharide Vaccine for Streptococcus pneumoniae Keratitis. Invest Ophthalmol Vis Sci 2011; 52:9232-43. [PMID: 22039231 DOI: 10.1167/iovs.10-6968] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The purpose of this study was to determine whether active immunization against pneumolysin (PLY), or polysaccharide capsule, protects against the corneal damage associated with Streptococcus pneumoniae keratitis. METHODS New Zealand White rabbits were actively immunized with Freund's adjuvant mixed with pneumolysin toxoid (ψPLY), Pneumovax 23 (PPSV23; Merck, Whitehouse Station, NJ), or phosphate-buffered saline (PBS), before corneal infection with 10⁵ colony-forming units (CFU) of S. pneumoniae. Serotype-specific rabbit polyclonal antisera or mock antisera were passively administered to rabbits before either intravenous infection with 10¹¹ CFU S. pneumoniae or corneal infection with 10⁵ CFU of S. pneumoniae. RESULTS After active immunization, clinical scores of corneas of the rabbits immunized with ψPLY and Freund's adjuvant were significantly lower than scores of the rabbits that were mock immunized with PBS and Freund's adjuvant or with PPSV23 and Freund's adjuvant at 48 hours after infection (P ≤ 0.0010), whereas rabbits immunized with PPSV23 and Freund's adjuvant failed to show differences in clinical scores compared with those in mock-immunized rabbits (P = 1.00) at 24 and 48 hours after infection. Antisera from rabbits actively immunized with PPSV23 and Freund's adjuvant were nonopsonizing. Bacterial loads recovered from infected corneas were higher for the ψPLY- and PPSV23-immunized rabbits after infection with WU2, when compared with the mock-immunized rabbits (P ≤ 0.007). Conversely, after infection with K1443, the ψPLY-immunized rabbits had lower bacterial loads than the control rabbits (P = 0.0008). Quantitation of IgG, IgA, and IgM in the sera of ψPLY-immunized rabbits showed high concentrations of PLY-specific IgG. Furthermore, anti-PLY IgG purified from ψPLY-immunized rabbits neutralized the cytolytic effects of PLY on human corneal epithelial cells. Passive administration of serotype-specific antisera capable of opsonizing and killing S. pneumoniae protected against pneumococcal bacteremia (P ≤ 0.05), but not against keratitis (P ≥ 0.476). CONCLUSIONS Active immunization with pneumococcal capsular polysaccharide and Freund's adjuvant fails to produce opsonizing antibodies, and passive administration of serotype specific opsonizing antibodies offers no protection against pneumococcal keratitis in the rabbit, whereas active immunization with the conserved protein virulence factor PLY and Freund's adjuvant is able to reduce corneal inflammation associated with pneumococcal keratitis, but has variable effects on bacterial loads in the cornea.
Collapse
Affiliation(s)
- Erin W Norcross
- Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Pneumococcal meningitis continues to be associated with high rates of mortality and long-term neurological sequelae. The most common route of infection starts by nasopharyngeal colonization by Streptococcus pneumoniae, which must avoid mucosal entrapment and evade the host immune system after local activation. During invasive disease, pneumococcal epithelial adhesion is followed by bloodstream invasion and activation of the complement and coagulation systems. The release of inflammatory mediators facilitates pneumococcal crossing of the blood-brain barrier into the brain, where the bacteria multiply freely and trigger activation of circulating antigen-presenting cells and resident microglial cells. The resulting massive inflammation leads to further neutrophil recruitment and inflammation, resulting in the well-known features of bacterial meningitis, including cerebrospinal fluid pleocytosis, cochlear damage, cerebral edema, hydrocephalus, and cerebrovascular complications. Experimental animal models continue to further our understanding of the pathophysiology of pneumococcal meningitis and provide the platform for the development of new adjuvant treatments and antimicrobial therapy. This review discusses the most recent views on the pathophysiology of pneumococcal meningitis, as well as potential targets for (adjunctive) therapy.
Collapse
|
21
|
Cao J, Gong Y, Cai B, Feng W, Wu Y, Li L, Zou Y, Ying B, Wang L. Modulation of human bronchial epithelial cells by pneumococcal choline binding protein A. Hum Immunol 2011; 72:37-46. [DOI: 10.1016/j.humimm.2010.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 09/25/2010] [Accepted: 10/06/2010] [Indexed: 11/26/2022]
|
22
|
Cao J, Gong Y, Yin Y, Wang L, Ying B, Chen T, Zhang X. Pneumococcal proteins PspA and PspC induce CXCL8 production in human neutrophils: implications in pneumococcal infections. Microbes Infect 2010; 12:1051-60. [PMID: 20670689 DOI: 10.1016/j.micinf.2010.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 07/07/2010] [Accepted: 07/09/2010] [Indexed: 02/07/2023]
Abstract
Surface-exposed pneumococcal virulence proteins pneumococcal surface protein A (PspA) and pneumococcal surface protein C (PspC) play important roles in the pathogenesis of invasive pneumococcal diseases. Human neutrophils are principle antimicrobial effector cells of the innate and adaptive immune systems. In this study, we investigated the effects of PspA and PspC on the up-regulation of chemokine CXCL8 in human neutrophils, and characterized the underlying intracellular signaling pathways. Both PspA and PspC were found to induce the release of newly synthesized CXCL8. Synergistic effect was observed in the combined treatment of PspA and PspC on the release of CXCL8. Products from PspA-deficient or PspC-deficient mutant pneumococcus that did not express PspA or PspC induced significantly less release of CXCL8 than wild type pneumococcus. Both PspA and PspC could activate p38 MAPK and NF-κB pathways in neutrophils, while inhibition of NF-κB and p38 MAPK could suppress the release of CXCL8 from neutrophils induced by PspA and PspC. Together, our results demonstrated that the induction of CXCL8 in human neutrophils activated by PspA and PspC was regulated by p38 MAPK and NF-κB pathways.
Collapse
Affiliation(s)
- Ju Cao
- Department of Laboratory Medicine, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu 610041, China.
| | | | | | | | | | | | | |
Collapse
|
23
|
Role of Toll-like receptors 2 and 4 in pulmonary inflammation and injury induced by pneumolysin in mice. PLoS One 2009; 4:e7993. [PMID: 19956717 PMCID: PMC2776357 DOI: 10.1371/journal.pone.0007993] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 10/27/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Pneumolysin (PLN) is an intracellular toxin of Streptococcus pneumoniae that has been implicated as a major virulence factor in infections caused by this pathogen. Conserved bacterial motifs are recognized by the immune system by pattern recognition receptors among which the family of Toll-like receptors (TLRs) prominently features. The primary objective of the present study was to determine the role of TLR2 and TLR4 in lung inflammation induced by intrapulmonary delivery of PLN. METHODOLOGY/RESULTS First, we confirmed that purified PLN activates cells via TLR4 (not via TLR2) in vitro, using human embryonic kidney cells transfected with either TLR2 or TLR4. Intranasal administration of PLN induced an inflammatory response in the pulmonary compartment of mice in vivo, as reflected by influx of neutrophils, release of proinflammatory cytokines and chemokines, and a rise in total protein concentrations in bronchoalveolar lavage fluid. These PLN-induced responses were dependent in part, not only on TLR4, but also on TLR2, as indicated by studies using TLR deficient mice. CONCLUSION These data suggest that although purified PLN is recognized by TLR4 in vitro, PLN elicits lung inflammation in vivo by mechanisms that may involve multiple TLRs.
Collapse
|
24
|
Joyce EA, Popper SJ, Falkow S. Streptococcus pneumoniae nasopharyngeal colonization induces type I interferons and interferon-induced gene expression. BMC Genomics 2009; 10:404. [PMID: 19712482 PMCID: PMC2743716 DOI: 10.1186/1471-2164-10-404] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 08/27/2009] [Indexed: 01/22/2023] Open
Abstract
Background We employed DNA microarray technology to investigate the host response to Streptococcus pneumoniae in a mouse model of asymptomatic carriage. Over a period of six weeks, we profiled transcript abundance and complexity in the Nasal Associated Lymphoid Tissue (NALT) to identify genes whose expression differed between pneumococcal-colonized and uncolonized states. Results Colonization with S. pneumoniae altered the expression of hundreds of genes over the course of the study, demonstrating that carriage is a dynamic process characterized by increased expression of a set of early inflammatory responses, including induction of a Type I Interferon response, and the production of several antimicrobial factors. Subsequent to this initial inflammatory response, we observed increases in transcripts associated with T cell development and activation, as well as wounding, basement membrane remodeling, and cell proliferation. Our analysis suggests that microbial colonization induced expression of genes encoding components critical for controlling JAK/STAT signaling, including stat1, stat2, socs3, and mapk1, as well as induction of several Type I Interferon-inducible genes and other antimicrobial factors at the earliest stages of colonization. Conclusion Examining multiple time points over six weeks of colonization demonstrated that asymptomatic carriage stimulates a dynamic host response characterized by temporal waves with distinct biological programs. Our data suggest that the usual response to the presence of the pneumocccus is an initial controlled inflammatory response followed by activation of host physiological processes such as response to wounding, basement membrane remodeling, and increasing cellular numbers that ultimately allow the host to maintain an intact epithelium and eventually mount a preventive adaptive immune response.
Collapse
Affiliation(s)
- Elizabeth A Joyce
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94131, USA.
| | | | | |
Collapse
|
25
|
Streptococcus pneumoniae autolysis prevents phagocytosis and production of phagocyte-activating cytokines. Infect Immun 2009; 77:3826-37. [PMID: 19528220 DOI: 10.1128/iai.00290-09] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Streptococcus pneumoniae is a major pathogen in humans. The pathogenicity of this organism is related to its many virulence factors, the most important of which is the thick pneumococcal capsule that minimizes phagocytosis. Another virulence-associated trait is the tendency of this bacterium to undergo autolysis in stationary phase through activation of the cell wall-bound amidase LytA, which breaks down peptidoglycan. The exact function of autolysis in pneumococcal pathogenesis is, however, unclear. Here, we show the selective and specific inefficiency of wild-type S. pneumoniae for inducing production of phagocyte-activating cytokines in human peripheral blood mononuclear cells (PBMC). Indeed, clinical pneumococcal strains induced production of 30-fold less tumor necrosis factor (TNF), 15-fold less gamma interferon (IFN-gamma), and only negligible amounts of interleukin-12 (IL-12) compared with other closely related Streptococcus species, whereas the levels of induction of IL-6, IL-8, and IL-10 production were similar. If pneumococcal LytA was inactivated by mutation or by culture in a medium containing excess choline, the pneumococci induced production of significantly more TNF, IFN-gamma, and IL-12 in PBMC, whereas the production of IL-6, IL-8, and IL-10 was unaffected. Further, adding autolyzed pneumococci to intact bacteria inhibited production of TNF, IFN-gamma, and IL-12 in a dose-dependent manner but did not inhibit production of IL-6, IL-8, and IL-10 in response to the intact bacteria. Fragments from autolyzed bacteria inhibited phagocytosis of intact bacteria and reduced the in vitro elimination of pneumococci from human blood. Our results suggest that fragments generated by autolysis of bacteria with reduced viability interfere with phagocyte-mediated elimination of live pneumococci.
Collapse
|
26
|
Bérubé LR, Roy D, Villeneuve N, Jarrell HC. Inhibition by Liposomal Cholesterol ofStreptococcus PneumoniaeInduced Lung Epithelial Cell Damage. J Liposome Res 2008. [DOI: 10.3109/08982109909035552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
27
|
Pneumolysin released during Streptococcus pneumoniae autolysis is a potent activator of intracellular oxygen radical production in neutrophils. Infect Immun 2008; 76:4079-87. [PMID: 18559434 DOI: 10.1128/iai.01747-07] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is a major cause of otitis media, pneumonia, meningitis, and septicemia in humans. The host defense against this pathogen largely depends on bacterial killing by neutrophils. A peculiar property of pneumococci is their tendency to undergo autolysis, i.e., autoinduced disruption of the bacterial cell wall mediated by activation of the enzyme LytA, under stationary growth conditions. LytA is a virulence factor, but the molecular background for this has not been fully clarified. Here we examine how bacterial compounds released upon autolysis affect the production of reactive oxygen species (ROS) in neutrophils. We found that the S. pneumoniae strains A17 and D39 induced activation of the NADPH oxidase and the production of ROS in human neutrophils and that this activation was blocked when LytA was inactivated. The ROS-inducing bacterial substance released from autolyzed bacteria was identified as the cytoplasmic toxin pneumolysin. Further screening of clinical pneumococcal strains of various sero- and genotypes revealed that selected strains expressing toxins with reduced pneumolysin-dependent hemolytic activity had decreased abilities to induce ROS in neutrophils. Furthermore, a mutated form of purified pneumolysin lacking hemolytic and complement binding functions (PdT) did not induce any oxygen radical production. The ROS produced in response to pneumolysin formed mainly intracellularly, which may explain why this production was not detected previously. ROS released intracellularly may function as signaling molecules, modifying the function of neutrophils in bacterial defense.
Collapse
|
28
|
Propst-Graham KL, Preheim LC, Vander Top EA, Snitily MU, Gentry-Nielsen MJ. Cirrhosis-induced defects in innate pulmonary defenses against Streptococcus pneumoniae. BMC Microbiol 2007; 7:94. [PMID: 17956621 PMCID: PMC2140065 DOI: 10.1186/1471-2180-7-94] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Accepted: 10/23/2007] [Indexed: 12/24/2022] Open
Abstract
Background The risk of mortality from pneumonia caused by Streptococcus pneumoniae is increased in patients with cirrhosis. However, the specific pneumococcal virulence factors and host immune defects responsible for this finding have not been clearly established. This study used a cirrhotic rat model of pneumococcal pneumonia to identify defect(s) in innate pulmonary defenses in the cirrhotic host and to determine the impact of the pneumococcal toxin pneumolysin on these defenses in the setting of severe cirrhosis. Results No cirrhosis-associated defects in mucociliary clearance of pneumococci were found in these studies, but early intrapulmonary killing of the organisms before the arrival of neutrophils was significantly impaired. This defect was exacerbated by pneumolysin production in cirrhotic but not in control rats. Neutrophil-mediated killing of a particularly virulent type 3 pneumococcal strain also was significantly diminished within the lungs of cirrhotic rats with ascites. Levels of lysozyme and complement component C3 were both significantly reduced in bronchoalveolar lavage fluid from cirrhotic rats. Finally, complement deposition was reduced on the surface of pneumococci recovered from the lungs of cirrhotic rats in comparison to organisms recovered from the lungs of control animals. Conclusion Increased mortality from pneumococcal pneumonia in this cirrhotic host is related to defects in both early pre-neutrophil- and later neutrophil-mediated pulmonary killing of the organisms. The fact that pneumolysin production impaired pre-neutrophil-mediated pneumococcal killing in cirrhotic but not control rats suggests that pneumolysin may be particularly detrimental to this defense mechanism in the severely cirrhotic host. The decrease in neutrophil-mediated killing of pneumococci within the lungs of the cirrhotic host is related to insufficient deposition of host proteins such as complement C3 on their surfaces. Pneumolysin likely plays a role in complement consumption within the lungs. Our studies, however, were unable to determine whether pneumolysin more negatively impacted this defense mechanism in cirrhotic than in control rats. These findings contribute to our understanding of the defects in innate pulmonary defenses that lead to increased mortality from pneumococcal pneumonia in the severely cirrhotic host. They also suggest that pneumolysin may be a particularly potent pneumococcal virulence factor in the setting of cirrhosis.
Collapse
Affiliation(s)
- Katie L Propst-Graham
- Department of Medical Microbiology and Immunology, Creighton University School of Medicine, Omaha, Nebraska, USA.
| | | | | | | | | |
Collapse
|
29
|
McCullers JA. Insights into the interaction between influenza virus and pneumococcus. Clin Microbiol Rev 2006; 19:571-82. [PMID: 16847087 PMCID: PMC1539103 DOI: 10.1128/cmr.00058-05] [Citation(s) in RCA: 601] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacterial infections following influenza are an important cause of morbidity and mortality worldwide. Based on the historical importance of pneumonia as a cause of death during pandemic influenza, the increasingly likely possibility that highly pathogenic avian influenza viruses will trigger the next worldwide pandemic underscores the need to understand the multiple mechanisms underlying the interaction between influenza virus and bacterial pathogens such as Streptococcus pneumoniae. There is ample evidence to support the historical view that influenza virus alters the lungs in a way that predisposes to adherence, invasion, and induction of disease by pneumococcus. Access to receptors is a key factor and may be facilitated by the virus through epithelial damage, by exposure or up-regulation of receptors, or by provoking the epithelial regeneration response to cytotoxic damage. More recent data indicate that alteration of the immune response by diminishing the ability of the host to clear pneumococcus or by amplification of the inflammatory cascade is another key factor. Identification and exploration of the underlying mechanisms responsible for this synergism will provide targets for prevention and treatment using drugs and vaccines.
Collapse
Affiliation(s)
- Jonathan A McCullers
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105-2794, USA.
| |
Collapse
|
30
|
Feldman C, Cockeran R, Jedrzejas MJ, Mitchell TJ, Anderson R. Hyaluronidase augments pneumolysin-mediated injury to human ciliated epithelium. Int J Infect Dis 2006; 11:11-5. [PMID: 16483814 DOI: 10.1016/j.ijid.2005.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 08/01/2005] [Accepted: 09/08/2005] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVES The main objective of this study was to investigate the effects of pneumococcal hyaluronidase (0.1-10microg/ml), alone and in combination with pneumolysin (50 and 100ng/ml), on human ciliated epithelium. METHODS Ciliary beat frequency (CBF) and structural integrity of human ciliated respiratory epithelium in vitro were studied using a phototransistor technique and a visual scoring index, respectively. RESULTS Hyaluronidase per se did not affect either CBF or the structural integrity of the epithelium. However, preincubation of the epithelial strips with hyaluronidase (10microg/ml) for 30min at 37 degrees C significantly potentiated pneumolysin-mediated ciliary slowing and epithelial damage. Hyaluronan, a substrate of hyaluronidase, had no effects on the ciliated respiratory epithelium in concentrations up to 100microg/ml and did not antagonize the injurious effects of pneumolysin on the epithelium. However, preincubation of the epithelial strips with hyaluronan (100microg/ml) was associated with attenuation of the ciliary slowing and epithelial damage induced by incubation of the strips with hyaluronidase (10microg/ml) for 30min at 37 degrees C followed by addition of pneumolysin (50ng/ml). CONCLUSIONS Although having no direct effects alone, hyaluronidase may contribute to pneumolysin-mediated damage and dysfunction to respiratory epithelium, thereby favoring colonization and subsequently extra-pulmonary dissemination of the pneumococcus.
Collapse
Affiliation(s)
- C Feldman
- Division of Pulmonology, Department of Medicine, Johannesburg Hospital and University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa.
| | | | | | | | | |
Collapse
|
31
|
Orihuela CJ, Fogg G, DiRita VJ, Tuomanen E. Bacterial Interactions with Mucosal Epithelial Cells. Mucosal Immunol 2005. [DOI: 10.1016/b978-012491543-5/50044-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
32
|
Hirst RA, Kadioglu A, O'callaghan C, Andrew PW. The role of pneumolysin in pneumococcal pneumonia and meningitis. Clin Exp Immunol 2004; 138:195-201. [PMID: 15498026 PMCID: PMC1809205 DOI: 10.1111/j.1365-2249.2004.02611.x] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Diseases caused by Streptococcus pneumoniae include pneumonia, septicaemia and meningitis. All these are associated with high morbidity and mortality. The pneumococcus can colonize the nasopharynx, and this can be a prelude to bronchopneumonia and invasion of the vasculature space. Proliferation in the blood can result in a breach of the blood-brain barrier and entry into the cerebrospinal fluid (CSF) where the bacteria cause inflammation of the meningeal membranes resulting in meningitis. The infected host may develop septicaemia and/or meningitis secondary to bronchopneumonia. Also septicaemia is a common precursor of meningitis. The mechanisms surrounding the sequence of infection are unknown, but will be dependent on the properties of both the host and bacterium. Treatment of these diseases with antibiotics leads to clearance of the bacteria from the infected tissues, but the bacteriolytic nature of antibiotics leads to an acute release of bacterial toxins and thus after antibiotic therapy the patients can be left with organ-specific deficits. One of the main toxins released from pneumococci is the membrane pore forming toxin pneumolysin. Here we review the extensive studies on the role of pneumolysin in the pathogenesis of pneumococcal diseases.
Collapse
Affiliation(s)
- R A Hirst
- Department of Infection, Inflamation and Immunity, University of Leicester, Leicester, UK.
| | | | | | | |
Collapse
|
33
|
Vesper SJ, Vesper MJ. Possible role of fungal hemolysins in sick building syndrome. ADVANCES IN APPLIED MICROBIOLOGY 2004; 55:191-213. [PMID: 15350795 DOI: 10.1016/s0065-2164(04)55007-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Stephen J Vesper
- U.S. Environmental Protection Agency Office of Research and Development, National Exposure Research Laboratory 26 W. M. L. King Drive Cincinnati, Ohio 45268, USA
| | | |
Collapse
|
34
|
Ebert S, Gerber J, Bader S, Mühlhauser F, Brechtel K, Mitchell TJ, Nau R. Dose-dependent activation of microglial cells by Toll-like receptor agonists alone and in combination. J Neuroimmunol 2004; 159:87-96. [PMID: 15652406 DOI: 10.1016/j.jneuroim.2004.10.005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 10/03/2004] [Accepted: 10/04/2004] [Indexed: 10/25/2022]
Abstract
Microglial cells express Toll-like receptors (TLRs) recognising exogenous and endogenous ligands. Upon stimulation with agonists of TLR2, TLR4, and TLR9, nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) were released by primary mouse microglial cell cultures. Endotoxin was most potent in stimulating microglia followed by pneumolysin, cytosine-guanosine (CpG) oligodesoxynucleotide (ODN), and Tripalmitoyl-S-glyceryl-cysteine. Maximum stimulation of TLR2, TLR4, and TLR9 resulted in approximately equal amounts of nitric oxide release. Pneumolysin was a potent activator of microglial cells; at high concentrations, it reduced cell viability. No cytotoxicity was noted with the other TLR agonists. Costimulation with maximum concentrations of two TLR agonists did not further increase nitric oxide release. Costimulation with submaximum concentrations was additive or supraadditive, suggesting that even low concentrations of products of infectious agents can lead to microglial activation via TLRs.
Collapse
Affiliation(s)
- Sandra Ebert
- Department of Neurology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
| | | | | | | | | | | | | |
Collapse
|
35
|
Cockeran R, Theron AJ, Feldman C, Mitchel TJ, Anderson R. Pneumolysin potentiates oxidative inactivation of alpha-1-proteinase inhibitor by activated human neutrophils. Respir Med 2004; 98:865-71. [PMID: 15338799 DOI: 10.1016/j.rmed.2004.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study was designed to investigate the effects of the Streptococcus pneumoniae-derived, pro-inflammatory toxin, pneumolysin (8.37 and 41.75 ng/ml), on the oxidative inactivation of alpha-1-protease inhibitor (API) by chemoattractant-activated human neutrophils in vitro. The elastase inhibitory capacity (EIC) of API in supernatants from unstimulated neutrophils, neutrophils treated with pneumolysin only, or with the chemoattractant FMLP (1 microM) only, or the combination of the toxin with FMLP was measured by a colorimetric procedure based on the activity of added porcine elastase. The EIC of API was unaffected by exposure to pneumolysin only, unstimulated neutrophils, or neutrophils treated with pneumolysin only. However, exposure to FMLP-activated neutrophils resulted in a reduction of the EIC of API, which was significantly (P<0.05) augmented by pneumolysin (mean reductions of 16%, 43% and 83% for FMLP only and in combination with 8.37 and 41.75 ng/ml pneumolysin, respectively), and was attenuated by wortmannin (1 microM), an inhibitor of NADPH oxidase, the oxidant-scavenger methionine (100 microM), and depletion of Ca2+ from the cell-suspending medium. These pro-proteolytic interactions of pneumolysin with chemoattractant-activated neutrophils may contribute to the invasiveness of the pneumococcus.
Collapse
Affiliation(s)
- Riana Cockeran
- MRC Unit for Inflammation and Immunity, Department of Immunology, Faculty of Health Sciences, University of Pretoria and Tshwane Academic Division of the National Health Laboratory Services, PO Box 2034, Pretoria 0001, South Africa
| | | | | | | | | |
Collapse
|
36
|
Huo Z, Spencer O, Miles J, Johnson J, Holliman R, Sheldon J, Riches P. Antibody response to pneumolysin and to pneumococcal capsular polysaccharide in healthy individuals and Streptococcus pneumoniae infected patients. Vaccine 2004; 22:1157-61. [PMID: 15003643 DOI: 10.1016/j.vaccine.2003.09.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2003] [Accepted: 09/26/2003] [Indexed: 11/23/2022]
Abstract
BACKGROUND Animal experiments have shown that antibodies against capsular polysaccharide enhance phagocytosis of pneumococcal bacteria and that antibodies against pneumolysin are anti-inflammatory and prevent pneumococcal invasion. It is not known if an antibody response to pneumolysin can be acquired from natural exposure to pneumococcal bacteria or how the concentration of pneumolysin antibody at the mucosal surface compares with that of antibodies against pneumococcal capsular polysaccharide. This study used an equal potency method to measure specific antibody concentrations against pneumolysin and pneumococcal capsular polysaccharides in order to facilitate comparative estimates of concentrations in saliva and serum. The results may provide experimental information as a basis for an improved pneumococcal vaccine strategy. RESULTS Healthy individuals had higher IgM and IgG antibody concentrations against capsular polysaccharide than against pneumolysin in both saliva and serum, but for IgA the converse was true. Patients with acute pneumococcal infection had significantly lower concentrations of specific IgG antibodies against both antigens than the healthy group. These patients also had significantly higher concentrations of IgM antibody against both antigens than the healthy control group. DISCUSSION Healthy individuals acquire a comparatively lower concentration of antibody to pneumolysin than to pneumococcal capsular polysaccharides from natural exposure to pneumococcal bacteria. Patients infected by pneumococcal bacteria have lower specific IgG antibody concentrations to both antigens than healthy individuals. These findings support the view that pneumolysin could potentially be used as a vaccine. For enhanced effectiveness, it could be used as a supplement to Pneumovax((R))II rather than as a replacement. The two acquired antibodies, i.e. to pneumolysin and to capsular polysaccharide, could then play their protective roles at different stages in the course of pneumococcal infection, and together contribute to an effective immune defence against Streptococcus pneumoniae.
Collapse
Affiliation(s)
- Z Huo
- Division of Biochemistry & Immunology, Department of Basic Medical Sciences, St. George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK.
| | | | | | | | | | | | | |
Collapse
|
37
|
Spreer A, Kerstan H, Böttcher T, Gerber J, Siemer A, Zysk G, Mitchell TJ, Eiffert H, Nau R. Reduced release of pneumolysin by Streptococcus pneumoniae in vitro and in vivo after treatment with nonbacteriolytic antibiotics in comparison to ceftriaxone. Antimicrob Agents Chemother 2003; 47:2649-54. [PMID: 12878534 PMCID: PMC166091 DOI: 10.1128/aac.47.8.2649-2654.2003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pneumolysin, a virulence factor of Streptococcus pneumoniae with cytotoxic and proinflammatory activities, occurs at concentrations from 0.85 to 180 ng/ml in cerebrospinal fluid (CSF) of meningitis patients. In pneumococcal cultures and in a rabbit meningitis model, the concentrations of pneumolysin in supernatant and CSF were lower after addition of nonbacteriolytic bactericidal antibiotics (rifampin and clindamycin) than after incubation with ceftriaxone.
Collapse
Affiliation(s)
- Annette Spreer
- Department of Neurology, University of Göttingen, Göttingen, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Feldman C, Anderson R, Cockeran R, Mitchell T, Cole P, Wilson R. The effects of pneumolysin and hydrogen peroxide, alone and in combination, on human ciliated epithelium in vitro. Respir Med 2002; 96:580-5. [PMID: 12195838 DOI: 10.1053/rmed.2002.1316] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have investigated the effects of pneumolysin and H2O2, putative virulence factors of Streptococcus pneumoniae, on the ciliary beat frequency and structural integrity of human ciliated epithelium in vitro. Human ciliated epithelium was obtained by brushing the inferior nasal turbinate of healthy human volunteers. Ciliary slowing (CS) was measured using a photo-transistor technique and epithelial damage (ED) was documented using a visual scoring index. Effects of recombinant pneumolysin (100 ng/ml), a mutant pneumolysin preparation with markedly reduced haemolytic activity (100 ng/ml) and reagent H2O2 (100 microM) were measured alone and in combination, in the absence and presence of catalase (1000 units/ml). When used individually, both recombinant pneumolysin and H2O2 caused significant (P < 0.05) CS and ED. The effects of H2O2 but not those of pneumolysin were almost completely attenuated by catalase, while the mutant pneumolysin preparation did not cause significant CS or ED. When used in combination, the effects of pneumolysin and H2O2 on CS and ED were additive as opposed to synergistic. These actions of pneumolysin and H2O2 may contribute to the pathogenesis of respiratory tract infections caused by the pneumococcus.
Collapse
Affiliation(s)
- C Feldman
- Division of Pulmonology, Department of Medicine, Johannesburg Hospital, University of the Witwatersrand, South Africa.
| | | | | | | | | | | |
Collapse
|
39
|
Ogunniyi AD, Giammarinaro P, Paton JC. The genes encoding virulence-associated proteins and the capsule of Streptococcus pneumoniae are upregulated and differentially expressed in vivo. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2045-2053. [PMID: 12101293 DOI: 10.1099/00221287-148-7-2045] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The polysaccharide capsule of Streptococcus pneumoniae and several well-characterized virulence proteins are known to contribute to the pathogenesis of pneumococcal disease. However, there is a paucity of data on the expression of their respective genes in vivo. In this study, the relative abundance of the mRNA transcripts of the genes encoding pneumolysin (ply), pneumococcal surface protein A (pspA), pneumococcal surface antigen A (psaA) and choline-binding protein A (cbpA), and of the first gene of the capsular polysaccharide biosynthesis locus (cps2A), was measured in virulent type 2 pneumococci harvested from the blood of BALB/c mice at 12 h and 24 h following intraperitoneal infection. The mRNA levels were then compared, using relative quantitative RT-PCR, with those present in organisms grown in serum broth. The expression of ply was upregulated threefold at 12 h, and 10-fold at 24 h post-infection; the expression of pspA and psaA was upregulated threefold and fivefold, respectively, at 12 h post-infection. Interestingly, the expression of pspA was 36-fold higher at 24 h post-infection whereas the expression of cps2A was upregulated approximately fourfold at 12 and 24 h post-infection. However, cbpA mRNA levels remained comparable in vivo and in vitro. When organisms were grown in whole blood or THY broth, the relative expression of these genes in the two growth media also differed markedly. This work provides direct molecular evidence that known virulence-associated genes of S. pneumoniae are differentially expressed in vivo. Data on the relative expression of these genes in different growth media also suggests that the regulation of expression of these genes is highly complex and multifactorial.
Collapse
Affiliation(s)
- A David Ogunniyi
- Department of Molecular Biosciences, Adelaide University, Adelaide, South Australia 5005, Australia1
| | - Philippe Giammarinaro
- Department of Molecular Biosciences, Adelaide University, Adelaide, South Australia 5005, Australia1
| | - James C Paton
- Department of Molecular Biosciences, Adelaide University, Adelaide, South Australia 5005, Australia1
| |
Collapse
|
40
|
Kadioglu A, Taylor S, Iannelli F, Pozzi G, Mitchell TJ, Andrew PW. Upper and lower respiratory tract infection by Streptococcus pneumoniae is affected by pneumolysin deficiency and differences in capsule type. Infect Immun 2002; 70:2886-90. [PMID: 12010976 PMCID: PMC128015 DOI: 10.1128/iai.70.6.2886-2890.2002] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2001] [Revised: 01/09/2002] [Accepted: 02/26/2002] [Indexed: 11/20/2022] Open
Abstract
Pneumococci frequently colonize the upper respiratory tract, and these pneumococci are believed to act as a reservoir for infection of the lower respiratory tract and bacteremia. We investigated how the pneumococcal toxin pneumolysin affects the capacity of pneumococci to infect the upper and lower respiratory tract of the mouse. Wild-type Streptococcus pneumoniae serotype 2 and 3 strains, a serotype 2 pneumolysin-deficient mutant, and a serotype 2 mutant with the pneumolysin gene reinserted were used to study differences in colonization and disease. In addition, we also examined a pneumococcal chimeric mutant (capsule type switched from serotype 2 to serotype 3) to gain further insight into the role that capsule plays in nasopharyngeal infection. Absence of pneumolysin was found to be associated with significantly lower numbers of pneumococci in the nasopharynx, trachea, and lungs. Differences in pneumococcal capsule type were found to have significant effects on pneumococcal infection of the nasopharynx, trachea, and lungs. However, it was the combination of capsule type and genetic background that was important, and the influence of this combination varied with the site of infection. For example, in the nasopharynx the wild-type serotype 3 strain and the capsule-switched mutant behaved similarly, whereas in the lungs the mutant that was switched to serotype 3 survived less well than the wild-type serotype 3 strain. The combination of capsule type and genetic background also determined virulence. Thus, the wild-type serotype 3 strain was virulent, whereas the capsule-switched mutant was avirulent.
Collapse
Affiliation(s)
- Aras Kadioglu
- Department of Microbiology and Immunology, University of Leicester, Leicester, LE1 United Kingdom.
| | | | | | | | | | | |
Collapse
|
41
|
|
42
|
Abstract
Several species of both pathogenic and non-pathogenic grampositive bacteria within the genera Streptococcus, Clostridium and Bacillus secrete cytolytic proteins that belong to a single, highly homologous family. The most widely known members of this family are streptolysin O, listeriolysin, perfringolysin, and pneumolysin. These toxins specifically require membrane cholesterol but, apparently, do not depend on any other specific cell surface receptor, so that they are able to lyse the cytoplasmic membranes of virtually any animal cell. Upon binding as monomers, they oligomerize to form large pores with up to 30 nm internal diameter. These are the largest pores known, permitting permeation not only of ions and small metabolites but also of macromolecules. The latter property renders these toxins useful tools in cell biology. While several of these cytolysins have been shown to be determinants of bacterial pathogenicity, their biological roles may vary, as do the lifestyles of the bacteria secreting them. A unique function is surely fulfilled by listeriolysin O, which helps the intracellular pathogen Listeria monocytogenes escape from phagolysosomes and then spread to adjacent host cells.
Collapse
Affiliation(s)
- M Palmer
- Department of Medical Biochemistry and Genetics, Texas A&M University, 440 Reynolds Medical Building, College Station, TX 77843-1114, USA.
| |
Collapse
|
43
|
Jero J, Virolainen A, Karma P. Clinical outcome of acute pneumococcal otitis media and serum antibody responses to pneumococcal pneumolysin and polysaccharides in children. ACTA OTO-LARYNGOLOGICA. SUPPLEMENTUM 2001; 543:63-6. [PMID: 10908980 DOI: 10.1080/000164800453991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Serum antibody responses to pneumococcal antigens and their relationship to the clinical outcome were determined in a prospective study of 121 children with acute otitis media (AOM). Pneumococcus positive children with a pneumolysin response more often had a recurrence and middle ear effusion (MEE) after 1 month than did the non-responders (p = 0.005 and p = 0.04, respectively). All the children who responded to pneumolysin also had clinically strong symptoms and signs of AOM. Children who responded to pneumococcal polysaccharides developed otitis media with effusion within a 6-month follow-up period more often than did the non-responders (p = 0.005). The results of this study suggest that children with pneumococcal AOM and an antibody response to the intracellular pneumococcal protein pneumolysin behave clinically differently from children with an antibody response to polysaccharides.
Collapse
Affiliation(s)
- J Jero
- Department of Otolaryngology, University of Helsinki, Finland
| | | | | |
Collapse
|
44
|
Kadioglu A, Sharpe JA, Lazou I, Svanborg C, Ockleford C, Mitchell TJ, Andrew PW. Use of green fluorescent protein in visualisation of pneumococcal invasion of broncho-epithelial cells in vivo. FEMS Microbiol Lett 2001; 194:105-10. [PMID: 11150674 DOI: 10.1111/j.1574-6968.2001.tb09454.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The pneumococcus is the principle cause of bacterial pneumonia and also a major cause of bacterial meningitis. The mechanisms and sites of pneumococcal adherence and invasion of the respiratory tract in vivo are not clear however. We have made pneumococci expressing green fluorescent protein (GFP) and used it to trace pneumococcal adherence and invasion in vivo. By using GFP pneumococci we have shown bacterial adherence and invasion of broncho-epithelial cells in vivo by 4 h post-infection, with increases in pneumococcal invasiveness by 24 h. Using confocal image analysis we have shown varying levels of pneumococcal penetration and internalisation into host cells, as well as translocation through epithelial layers. To our knowledge this is the first report of pneumococcal invasion and cellular translocation in vivo.
Collapse
Affiliation(s)
- A Kadioglu
- Department of Microbiology and Immunology, University of Leicester, LE1 9HN, UK
| | | | | | | | | | | | | |
Collapse
|
45
|
Orihuela CJ, Janssen R, Robb CW, Watson DA, Niesel DW. Peritoneal culture alters Streptococcus pneumoniae protein profiles and virulence properties. Infect Immun 2000; 68:6082-6. [PMID: 10992528 PMCID: PMC101580 DOI: 10.1128/iai.68.10.6082-6086.2000] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2000] [Accepted: 07/03/2000] [Indexed: 11/20/2022] Open
Abstract
We have examined the properties of Streptococcus pneumoniae cultured in the murine peritoneal cavity and compared its virulence-associated characteristics to those of cultures grown in vitro. Analysis of mRNA levels for specific virulence factors demonstrated a 2.8-fold increase in ply expression and a 2.2-fold increase in capA3 expression during murine peritoneal culture (MPC). Two-dimensional gels and immunoblots using convalescent-phase patient sera and murine sera revealed distinct differences in protein production in vivo (MPC). MPC-grown pneumococci adhered to A549 epithelial cell lines at levels 10-fold greater than those cultured in vitro.
Collapse
Affiliation(s)
- C J Orihuela
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-1019, USA
| | | | | | | | | |
Collapse
|
46
|
Abstract
Pneumolysin is a thiol-activated membrane-damaging toxin produced by Streptococcus pneumoniae. The toxin plays a role in virulence of the pneumococcus in animal models of infection. Pneumolysin has a range of biological activity including the ability to lyse eukaryotic cells and to interfere with the function of cells and soluble molecules of the immune system. The use of purified native and mutant toxin and of isogenic mutants of the pneumococcus expressing altered versions of the toxin has allowed the contribution of the various activities of this multifunctional toxin to virulence to be defined.
Collapse
Affiliation(s)
- T J Mitchell
- Division of Infection and Immunity, University of Glasgow, Scotland
| | | |
Collapse
|
47
|
Abstract
Streptococcus pneumoniae infection and disease have been modeled in several animal species including infant and adult mice, infant and adult rats, infant Rhesus monkeys, and adolescent and adult chinchillas. Most are models of sepsis arising from intravenous or intraperitoneal inoculation of bacteria, and a few were designed to study disease arising from intranasal infection. Chinchillas provide the only animal model of middle ear pneumococcal infection in which the disease can be produced by very small inocula injected into the middle ear (ME) or intranasally, and in which the disease remains localized to the ME in most cases. This model, developed at the University of Minnesota in 1975, has been used to study pneumococcal pathogenesis at a mucosal site, immunogenicity and efficacy of pneumococcal capsular polysaccharide (PS) vaccine antigens, and the kinetics and efficacy of antimicrobial drugs. Pathogenesis experiments in the chinchilla model have revealed variation in ME virulence among different pneumococcal serotypes, enhancement of ME infection during concurrent intranasal influenza A virus infections, and natural resolution of pneumococcal otitis media (OM) without intervention. Research has explored the relative contribution of pneumococcal and host products to ME inflammation. Pneumococcal cell wall components and pneumolysin have been studied in the model. Host inflammatory responses studied in the chinchilla ME include polymorphonuclear leukocyte oxidative products, hydrolytic enzymes, cytokine and eicosanoid metabolites, and ME epithelial cell adhesion and mucous glycoprotein production. Both clinical (tympanic membrane appearance) and histopathology (ME, Eustachian tube, inner ear) endpoints can be quantified. Immunologic and inflammatory studies have been facilitated by the production of affinity-purified antichinchilla immunoglobulin G (IgG), IgM, and secretory IgA polyclonal antibody reagents, and the identification of cross-reactivity between human and chinchilla cytokines, and between guinea pig and chinchilla C3. Alteration of ME mucosa by pneumococcal neuraminidase and alteration of ME epithelial cell (MEEC) surface carbohydrates during intranasal pneumococcal infection have been demonstrated. Pathogenesis studies have been aided by cultured chinchilla MEEC systems, in which the ability of platelet activating factor and interleukin (IL)-1 beta to stimulate epithelial mucous glycoprotein synthesis has recently been demonstrated. Because chronic OM with effusion is characterized by presence of large amounts of mucous glycoprotein in the ME, pneumococcus may have an important role in both acute and chronic ME disease. Both unconjugated PS and PS-protein-conjugated vaccines are immunogenic after intramuscular administration without adjuvant in chinchillas. Passive protection studies with human hyperimmune immunoglobulin demonstrated that anti-PS IgG alone is capable of protecting the chinchilla ME from direct ME challenge with pneumococci. Active PS immunization studies demonstrated protection following direct ME and intranasal pneumococcal challenge with and without concurrent influenza A virus infection. An attenuated influenza A virus vaccine also showed protection for pneumococcal OM. Antimicrobial treatment of acute OM has been based almost exclusively on empirical drug use and clinical trials without a foundation of ME pharmacokinetics. Studies in the chinchilla model have started to bring a rational basis to drug selection and dosing. Microassays have been developed using high-pressure liquid chromatography for many relevant drugs. Studies have explored the in vivo ME response in pneumococcal OM to antimicrobial drugs at supra- and sub-minimum inhibitory concentration (MIC), the effect of concurrent influenza A virus infection on ME drug penetration, and the effect of treatment on sensorineural hearing loss produced by pneumococcal OM.
Collapse
Affiliation(s)
- G S Giebink
- Otitis Media Research Center, University of Minnesota School of Medicine, Minneapolis 55455, USA
| |
Collapse
|
48
|
Andrew PW, Mitchell TJ, Morgan PJ. Relationship of structure to function in pneumolysin. Microb Drug Resist 2000; 3:11-7. [PMID: 9109092 DOI: 10.1089/mdr.1997.3.11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- P W Andrew
- Department of Microbiology and Immunology, University of Leicester, UK
| | | | | |
Collapse
|
49
|
Hirst RA, Rutman A, Sikand K, Andrew PW, Mitchell TJ, O'Callaghan C. Effect of pneumolysin on rat brain ciliary function: comparison of brain slices with cultured ependymal cells. Pediatr Res 2000; 47:381-4. [PMID: 10709739 DOI: 10.1203/00006450-200003000-00016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This study compares two models for examining ependymal ciliary function: rat brain slices cut from the fourth ventricle and primary ependymal cells in culture. The cilia from both preparations were very reproducible; each preparation had cilia beating at a constant frequency of between 38 and 44 Hz. With the brain slices, ciliary stasis occurred after 5 d in culture. However, ependymal cells had fully functional cilia for up to 48 d in culture. The pneumococcal toxin, pneumolysin, caused a dose-dependent inhibition of cilia beat frequency within 15 min in both models. There were no significant differences in the mean log 50% inhibitory concentration (pIC50) slice = 0.65 +/- 0.05, equivalent to 4.4 hemolytic units (HU)/mL; cells = 0.57 +/- 0.14, equivalent to 3.7 HU/mL. There were also no significant differences in the mean Hill slope factors for the curves (slice = 1.4 +/- 0.05; cells = 1.6 +/- 0.4). These data demonstrate that both models can be used to examine the acute (15-min) effects of pneumolysin on cilia beat frequency. The main advantage of the primary ependymal culture model is that considerably more cultured ependymal cells (approximately 70%) are available, compared with the number of ependymal cells on the brain slices (approximately 2%), thus reducing the number of animals used. A pure ependymal culture was not achieved (approximately 30% of the cells were not ciliated). The increased survival time of the ependymal cells compared with the brain slices make cultured ependymal cells more useful for examining long-term ciliary function, whereas brain slices may be more useful for examining the interactions between ependymal and other nearby cells.
Collapse
Affiliation(s)
- R A Hirst
- Department of Child Health, Leicester Royal Infirmary, University of Leicester, England, UK
| | | | | | | | | | | |
Collapse
|
50
|
Kadioglu A, Gingles NA, Grattan K, Kerr A, Mitchell TJ, Andrew PW. Host cellular immune response to pneumococcal lung infection in mice. Infect Immun 2000; 68:492-501. [PMID: 10639409 PMCID: PMC97168 DOI: 10.1128/iai.68.2.492-501.2000] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although there is substantial evidence that pneumolysin is an important virulence factor in pneumococcal pneumonia, relatively little is known about how it influences cellular infiltration into the lungs. We investigated how the inability of mutant pneumococci to produce pneumolysin altered the pattern of inflammation and cellular infiltration into the lungs. The effect on bacterial growth in the lungs also was assessed. There were three phases of growth of wild-type bacteria in the lungs: a decline followed by a rapid increase and then stasis or decline. The absence of pneumolysin was associated with a more rapid early decline and then a much slower increase in numbers. The pattern of inflammatory-cell accumulation also had distinct stages, and the timing of these stages was influenced by the presence of pneumolysin. Neutrophils began to accumulate about 12 to 16 h after infection with wild-type pneumococci. This accumulation occurred after the early decline in pneumococcal numbers but coincided with the period of rapid growth. Following infection with pneumococci unable to make pneumolysin, neutrophil influx was slower and less intense. Coincident with the third stage of pneumococcal growth was an accumulation of T and B lymphocytes at the sites of inflammation, but the accumulation was not associated with an increase in the total number of lymphocytes in the lungs. Lymphocyte accumulation in the absence of pneumolysin occurred but was delayed.
Collapse
Affiliation(s)
- A Kadioglu
- Department of Microbiology & Immunology, University of Leicester, Leicester, United Kingdom
| | | | | | | | | | | |
Collapse
|