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Xu J, Zhu J, Han W, Pang S, Deng S, Chen L, Chen X, Huang Q, Zhou R, Li L. A bifunctional amylopullulanase of Streptococcus suis ApuA contributes to immune evasion by interaction with host complement C3b. Vet Microbiol 2024; 297:110212. [PMID: 39111202 DOI: 10.1016/j.vetmic.2024.110212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/28/2024] [Accepted: 08/02/2024] [Indexed: 08/25/2024]
Abstract
The complement system is the first defense line of the immune system. However, pathogens have evolved numerous strategies to evade complement attacks. Streptococcus suis is an important zoonotic bacterium, harmful to both the pig industry and human health. ApuA has been reported as a bifunctional amylopullulanase and also contributed to virulence of S. suis. Herein, we found that ApuA could activate both classical and alternative pathways of the complement system. Furthermore, by using bacterial two-hybrid, far-western blot and ELISA assays, it was confirmed that ApuA could interact with complement C3b. The interaction domain of ApuA with C3b was found to be its α-Amylase domain (ApuA_N). After construction of an apuA mutant (ΔapuA) and its complementary strain, it was found that compared to the wild-type strain (WT), ΔapuA had significantly increased C3b deposition and membrane attack complex formation. Additionally, ΔapuA showed significantly lower survival rates in human serum and blood and was more susceptible to engulfment by neutrophils and macrophages. Mice infected with ΔapuA had significantly higher survival rates and lower bacterial loads in their blood, lung and brains, compared to those infected with WT. In summary, this study identified ApuA as a novel factor involved in the complement evasion of S. suis and suggested its multifunctional role in the pathogenesis of S. suis.
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Affiliation(s)
- Jiajia Xu
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Jiaqi Zhu
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Weiyao Han
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Siqi Pang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Simin Deng
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Long Chen
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Xiabing Chen
- Institute of Animal Husbandry and Veterinary Science, Wuhan Academy of Agricultural Sciences, Wuhan, Hubei, China
| | - Qi Huang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei 430070, China
| | - Rui Zhou
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei 430070, China.
| | - Lu Li
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei 430070, China.
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Zhang C, Liu J, Liu X, Xu Y, Gan Q, Cheng Q, Liu W, Gao X, Wu S. Glutamine enhances pneumococcal growth under methionine semi-starvation by elevating intracellular pH. Front Microbiol 2024; 15:1430038. [PMID: 39044959 PMCID: PMC11263215 DOI: 10.3389/fmicb.2024.1430038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 06/28/2024] [Indexed: 07/25/2024] Open
Abstract
Introduction Bacteria frequently encounter nutrient limitation in nature. The ability of living in this nutrient shortage environment is vital for bacteria to preserve their population and important for some pathogenic bacteria to cause infectious diseases. Usually, we study how bacteria survive after nutrient depletion, a total starvation condition when bacteria almost cease growth and try to survive. However, nutrient limitation may not always lead to total starvation. Methods Bacterial adaptation to nutrient shortage was studied by determining bacterial growth curves, intracellular pH, intracellular amino acid contents, gene transcription, protein expression, enzyme activity, and translation and replication activities. Results No exogenous supply of methionine results in growth attenuation of Streptococcus pneumoniae, a human pathogen. In this paper, we refer to this inhibited growth state between ceased growth under total starvation and full-speed growth with full nutrients as semi-starvation. Similar to total starvation, methionine semi-starvation also leads to intracellular acidification. Surprisingly, it is intracellular acidification but not insufficient methionine synthesis that causes growth attenuation under methionine semi-starvation. With excessive glutamine supply in the medium, intracellular methionine level was not changed, while bacterial intracellular pH was elevated to ~ 7.6 (the optimal intracellular pH for pneumococcal growth) by glutamine deamination, and bacterial growth under semi-starvation was restored fully. Our data suggest that intracellular acidification decreases translation level and glutamine supply increases intracellular pH to restore translation level, thus restoring bacterial growth. Discussion This growth with intracellular pH adjustment by glutamine is a novel strategy we found for bacterial adaptation to nutrient shortage, which may provide new drug targets to inhibit growth of pathogenic bacteria under semi-starvation.
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Affiliation(s)
- Chengwang Zhang
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Juncheng Liu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Xiaohui Liu
- National Protein Science Facility, Tsinghua University, Beijing, China
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Yueyu Xu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Qingxiu Gan
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Qinqian Cheng
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Weiping Liu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Xiangmin Gao
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Songquan Wu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
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Loh JM, Aghababa H, Proft T. Eluding the immune system's frontline defense: Secreted complement evasion factors of pathogenic Gram-positive cocci. Microbiol Res 2023; 277:127512. [PMID: 37826985 DOI: 10.1016/j.micres.2023.127512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/01/2023] [Accepted: 10/04/2023] [Indexed: 10/14/2023]
Abstract
The human complement system is an important part of the innate immune response in the fight against invasive bacteria. Complement responses can be activated independently by the classical pathway, the lectin pathway, or the alternative pathway, each resulting in the formation of a C3 convertase that produces the anaphylatoxin C3a and the opsonin C3b by specifically cutting C3. Other important features of complement are the production of the chemotactic C5a peptide and the generation of the membrane attack complex to lyse intruding pathogens. Invasive pathogens like Staphylococcus aureus and several species of the genus Streptococcus have developed a variety of complement evasion strategies to resist complement activity thereby increasing their virulence and potential to cause disease. In this review, we focus on secreted complement evasion factors that assist the bacteria to avoid opsonization and terminal pathway lysis. We also briefly discuss the potential role of complement evasion factors for the development of vaccines and therapeutic interventions.
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Affiliation(s)
- Jacelyn Ms Loh
- Department of Molecular Medicine & Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Haniyeh Aghababa
- Department of Molecular Medicine & Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Thomas Proft
- Department of Molecular Medicine & Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand.
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Rafi MO, Al-Khafaji K, Mandal SM, Meghla NS, Biswas PK, Rahman MS. A subunit vaccine against pneumonia: targeting S treptococcus pneumoniae and Klebsiella pneumoniae. NETWORK MODELING AND ANALYSIS IN HEALTH INFORMATICS AND BIOINFORMATICS 2023; 12:21. [PMID: 37096010 PMCID: PMC10115389 DOI: 10.1007/s13721-023-00416-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 03/25/2023] [Accepted: 04/09/2023] [Indexed: 04/26/2023]
Abstract
Community-acquired pneumonia is primarily caused by Streptococcus pneumoniae and Klebsiella pneumoniae, two pathogens that have high morbidity and mortality rates. This is largely due to bacterial resistance development against current antibiotics and the lack of effective vaccines. The objective of this work was to develop an immunogenic multi-epitope subunit vaccine capable of eliciting a robust immune response against S. pneumoniae and K. pneumoniae. The targeted proteins were the pneumococcal surface proteins (PspA and PspC) and choline-binding protein (CbpA) of S. pneumoniae and the outer membrane proteins (OmpA and OmpW) of K. pneumoniae. Different computational approaches and various immune filters were employed for designing a vaccine. The immunogenicity and safety of the vaccine were evaluated by utilizing many physicochemical and antigenic profiles. To improve structural stability, disulfide engineering was applied to a portion of the vaccine structure with high mobility. Molecular docking was performed to examine the binding affinities and biological interactions at the atomic level between the vaccine and Toll-like receptors (TLR2 and 4). Further, the dynamic stabilities of the vaccine and TLRs complexes were investigated by molecular dynamics simulations. While the immune response induction capability of the vaccine was assessed by the immune simulation study. Vaccine translation and expression efficiency was determined through an in silico cloning experiment utilizing the pET28a(+) plasmid vector. The obtained results revealed that the designed vaccine is structurally stable and able to generate an effective immune response to combat pneumococcal infection. Supplementary Information The online version contains supplementary material available at 10.1007/s13721-023-00416-3.
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Affiliation(s)
- Md. Oliullah Rafi
- Bioinformatics and Microbial Biotechnology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology, Jashore, 7408 Bangladesh
- Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology, Jashore, 7408 Bangladesh
| | | | - Santi M. Mandal
- Central Research Facility, Indian Institute of Technology Kharagpur, Kharagpur, 721302 India
| | - Nigar Sultana Meghla
- Department of Microbiology, Jashore University of Science and Technology, Jashore, 7408 Bangladesh
| | - Polash Kumar Biswas
- Department of Stem Cell and Regenerative Biotechnology, Incurable Disease Animal Model & Stem Cell Institute (IDASI), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 05029 South Korea
| | - Md. Shahedur Rahman
- Bioinformatics and Microbial Biotechnology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology, Jashore, 7408 Bangladesh
- Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology, Jashore, 7408 Bangladesh
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Pettersen JS, Høg FF, Nielsen FD, Møller-Jensen J, Jørgensen MG. Global transcriptional responses of pneumococcus to human blood components and cerebrospinal fluid. Front Microbiol 2022; 13:1060583. [PMID: 36620004 PMCID: PMC9812572 DOI: 10.3389/fmicb.2022.1060583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/22/2022] [Indexed: 12/24/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is a leading cause of severe invasive infectious diseases such as sepsis and meningitis. Understanding how pneumococcus adapts and survive in the human bloodstream environment and cerebrospinal fluid (CSF) is important for development of future treatment strategies. This study investigates the global transcriptional response of pneumococcus to human blood components and CSF acquired from discarded and anonymized patient samples. Extensive transcriptional changes to human blood components were observed during early stages of interaction. Plasma-specific responses were primarily related to metabolic components and include strong downregulation of fatty acid biosynthesis genes, and upregulation of nucleotide biosynthesis genes. No transcriptional responses specific to the active plasma proteins (e.g., complement proteins) were observed during early stages of interaction as demonstrated by a differential expression analysis between plasma and heat-inactivated plasma. The red blood cell (RBC)-specific response was far more complex, and included activation of the competence system, differential expression of several two-component systems, phosphotransferase systems and transition metal transporter genes. Interestingly, most of the changes observed for CSF were also observed for plasma. One of the few CSF-specific responses, not observed for plasma, was a strong downregulation of the iron acquisition system piuBCDA. Intriguingly, this transcriptomic analysis also uncovers significant differential expression of more than 20 small non-coding RNAs, most of them in response to RBCs, including small RNAs from uncharacterized type I toxin-antitoxin systems. In summary, this transcriptomic study identifies key pneumococcal metabolic pathways and regulatory genes involved with adaptation to human blood and CSF. Future studies should uncover the potential involvement of these factors with virulence in-vivo.
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Schulz K, Trendelenburg M. C1q as a target molecule to treat human disease: What do mouse studies teach us? Front Immunol 2022; 13:958273. [PMID: 35990646 PMCID: PMC9385197 DOI: 10.3389/fimmu.2022.958273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 06/24/2022] [Indexed: 11/17/2022] Open
Abstract
The complement system is a field of growing interest for pharmacological intervention. Complement protein C1q, the pattern recognition molecule at the start of the classical pathway of the complement cascade, is a versatile molecule with additional non-canonical actions affecting numerous cellular processes. Based on observations made in patients with hereditary C1q deficiency, C1q is protective against systemic autoimmunity and bacterial infections. Accordingly, C1q deficient mice reproduce this phenotype with susceptibility to autoimmunity and infections. At the same time, beneficial effects of C1q deficiency on disease entities such as neurodegenerative diseases have also been described in murine disease models. This systematic review provides an overview of all currently available literature on the C1q knockout mouse in disease models to identify potential target diseases for treatment strategies focusing on C1q, and discusses potential side-effects when depleting and/or inhibiting C1q.
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Affiliation(s)
- Kristina Schulz
- Laboratory of Clinical Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland
- Division of Internal Medicine, University Hospital Basel, Basel, Switzerland
- *Correspondence: Kristina Schulz,
| | - Marten Trendelenburg
- Laboratory of Clinical Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland
- Division of Internal Medicine, University Hospital Basel, Basel, Switzerland
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Gil E, Noursadeghi M, Brown JS. Streptococcus pneumoniae interactions with the complement system. Front Cell Infect Microbiol 2022; 12:929483. [PMID: 35967850 PMCID: PMC9366601 DOI: 10.3389/fcimb.2022.929483] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/08/2022] [Indexed: 11/21/2022] Open
Abstract
Host innate and adaptive immunity to infection with Streptococcus pneumoniae is critically dependent on the complement system, demonstrated by the high incidence of invasive S. pneumoniae infection in people with inherited deficiency of complement components. The complement system is activated by S. pneumoniae through multiple mechanisms. The classical complement pathway is activated by recognition of S. pneumoniae by C-reactive protein, serum amyloid P, C1q, SIGN-R1, or natural or acquired antibody. Some S. pneumoniae strains are also recognised by ficolins to activate the mannose binding lectin (MBL) activation pathway. Complement activation is then amplified by the alternative complement pathway, which can also be activated by S. pneumoniae directly. Complement activation results in covalent linkage of the opsonic complement factors C3b and iC3b to the S. pneumoniae surface which promote phagocytic clearance, along with complement-mediated immune adherence to erythrocytes, thereby protecting against septicaemia. The role of complement for mucosal immunity to S. pneumoniae is less clear. Given the major role of complement in controlling infection with S. pneumoniae, it is perhaps unsurprising that S. pneumoniae has evolved multiple mechanisms of complement evasion, including the capsule, multiple surface proteins, and the toxin pneumolysin. There is considerable variation between S. pneumoniae capsular serotypes and genotypes with regards to sensitivity to complement which correlates with ability to cause invasive infections. However, at present we only have a limited understanding of the main mechanisms causing variations in complement sensitivity between S. pneumoniae strains and to non-pathogenic streptococci.
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Affiliation(s)
- Eliza Gil
- Division of Infection and Immunity, University College London, London, United Kingdom
- *Correspondence: Eliza Gil,
| | - Mahdad Noursadeghi
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Jeremy S. Brown
- Division of Medicine, University College London, London, United Kingdom
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Pereira JM, Xu S, Leong JM, Sousa S. The Yin and Yang of Pneumolysin During Pneumococcal Infection. Front Immunol 2022; 13:878244. [PMID: 35529870 PMCID: PMC9074694 DOI: 10.3389/fimmu.2022.878244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/23/2022] [Indexed: 12/15/2022] Open
Abstract
Pneumolysin (PLY) is a pore-forming toxin produced by the human pathobiont Streptococcus pneumoniae, the major cause of pneumonia worldwide. PLY, a key pneumococcal virulence factor, can form transmembrane pores in host cells, disrupting plasma membrane integrity and deregulating cellular homeostasis. At lytic concentrations, PLY causes cell death. At sub-lytic concentrations, PLY triggers host cell survival pathways that cooperate to reseal the damaged plasma membrane and restore cell homeostasis. While PLY is generally considered a pivotal factor promoting S. pneumoniae colonization and survival, it is also a powerful trigger of the innate and adaptive host immune response against bacterial infection. The dichotomy of PLY as both a key bacterial virulence factor and a trigger for host immune modulation allows the toxin to display both "Yin" and "Yang" properties during infection, promoting disease by membrane perforation and activating inflammatory pathways, while also mitigating damage by triggering host cell repair and initiating anti-inflammatory responses. Due to its cytolytic activity and diverse immunomodulatory properties, PLY is integral to every stage of S. pneumoniae pathogenesis and may tip the balance towards either the pathogen or the host depending on the context of infection.
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Affiliation(s)
- Joana M. Pereira
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Molecular and Cellular (MC) Biology PhD Program, ICBAS - Instituto de Ciência Biomédicas Abel Salazar, University of Porto, Porto, Portugal
| | - Shuying Xu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States
- Graduate Program in Immunology, Tufts Graduate School of Biomedical Sciences, Boston, MA, United States
| | - John M. Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States
| | - Sandra Sousa
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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Marshall H, José RJ, Kilian M, Petersen FC, Brown JS. Effects of Expression of Streptococcus pneumoniae PspC on the Ability of Streptococcus mitis to Evade Complement-Mediated Immunity. Front Microbiol 2021; 12:773877. [PMID: 34880844 PMCID: PMC8646030 DOI: 10.3389/fmicb.2021.773877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Streptococcus pneumoniae and Streptococcus mitis are genetically closely related and both frequently colonise the naso-oropharynx, yet S. pneumoniae is a common cause of invasive infections whereas S. mitis is only weakly pathogenic. We hypothesise that sensitivity to innate immunity may underlie these differences in virulence phenotype. We compared the sensitivity of S. pneumoniae and S. mitis strains to complement-mediated immunity, demonstrating S. mitis strains were susceptible to complement-mediated opsonophagocytosis. S. pneumoniae resistance to complement is partially dependent on binding of the complement regulator Factor H by the surface protein PspC. However, S. mitis was unable to bind factor H. The S. pneumoniae TIGR4 strain pspC was expressed in the S. mitis SK142 strain to create a S. mitis pspC+ strain. Immunoblots demonstrated the S. mitis pspC+ strain expressed PspC, and flow cytometry confirmed this resulted in Factor H binding to S. mitis, reduced susceptibility to complement and improved survival in whole human blood compared to the wild-type S. mitis strain. However, in mouse models the S. mitis pspC+ strain remained unable to establish persistent infection. Unlike S. pneumoniae strains, culture in serum or blood did not support increased CFU of the S. mitis strains. These results suggest S. mitis is highly sensitive to opsonisation with complement partially due to an inability to bind Factor H, but even when complement sensitivity was reduced by expression of pspC, poor growth in physiological fluid limited the virulence of S. mitis in mice.
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Affiliation(s)
- Helina Marshall
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Department of Medicine, Royal Free and University College Medical School, University College London, London, United Kingdom.,Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Ricardo J José
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Department of Medicine, Royal Free and University College Medical School, University College London, London, United Kingdom
| | - Mogens Kilian
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Fernanda C Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Jeremy S Brown
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Department of Medicine, Royal Free and University College Medical School, University College London, London, United Kingdom
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Single nucleotide polymorphisms within the cps loci: another potential source of clinically important genetic variation for Streptococcus pneumoniae? Infect Immun 2021; 89:e0037421. [PMID: 34338550 DOI: 10.1128/iai.00374-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Streptococcus pneumoniae capsule is essential for disease pathogenesis, suggesting that even minor genetic changes within the cps locus could potentially have important consequences. Arends et al. have identified 79 different non-synonymous SNPs in the cps locus of 338 19A serotype strains, and shown significant variations between strains in nucleotide sugars content and capsule shedding. Further work is required to characterise whether any of these changes have important functional consequences on capsule/host interactions.
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Pneumococcal Choline-Binding Proteins Involved in Virulence as Vaccine Candidates. Vaccines (Basel) 2021; 9:vaccines9020181. [PMID: 33672701 PMCID: PMC7924319 DOI: 10.3390/vaccines9020181] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 01/25/2023] Open
Abstract
Streptococcus pneumoniae is a pathogen responsible for millions of deaths worldwide. Currently, the available vaccines for the prevention of S. pneumoniae infections are the 23-valent pneumococcal polysaccharide-based vaccine (PPV-23) and the pneumococcal conjugate vaccines (PCV10 and PCV13). These vaccines only cover some pneumococcal serotypes (up to 100 different serotypes have been identified) and are unable to protect against non-vaccine serotypes and non-encapsulated pneumococci. The emergence of antibiotic-resistant non-vaccine serotypes after these vaccines is an increasing threat. Therefore, there is an urgent need to develop new pneumococcal vaccines which could cover a wide range of serotypes. One of the vaccines most characterized as a prophylactic alternative to current PPV-23 or PCVs is a vaccine based on pneumococcal protein antigens. The choline-binding proteins (CBP) are found in all pneumococcal strains, giving them the characteristic to be potential vaccine candidates as they may protect against different serotypes. In this review, we have focused the attention on different CBPs as vaccine candidates because they are involved in the pathogenesis process, confirming their immunogenicity and protection against pneumococcal infection. The review summarizes the major contribution of these proteins to virulence and reinforces the fact that antibodies elicited against many of them may block or interfere with their role in the infection process.
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Panagiotou S, Chaguza C, Yahya R, Audshasai T, Baltazar M, Ressel L, Khandaker S, Alsahag M, Mitchell TJ, Prudhomme M, Kadioglu A, Yang M. Hypervirulent pneumococcal serotype 1 harbours two pneumolysin variants with differential haemolytic activity. Sci Rep 2020; 10:17313. [PMID: 33057054 PMCID: PMC7560715 DOI: 10.1038/s41598-020-73454-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/14/2020] [Indexed: 12/13/2022] Open
Abstract
Streptococcus pneumoniae is a devastating global pathogen. Prevalent in sub-Saharan Africa, pneumococcal serotype 1 is atypical in that it is rarely found as a nasopharyngeal coloniser, yet is described as one of the most common causes of invasive pneumococcal disease. Clonal sequence type (ST)-306 and ST615 are representative of the two major serotype 1 lineages A and C, respectively. Here we investigated the virulence properties and haemolytic activities of these 2 clonal types using in vivo mouse models and in vitro assays. A lethal dose of ST615 administered intranasally to mice led to the rapid onset of disease symptoms and resulted in 90% mortality. In contrast, mice exposed to the same infection dose of ST306 or a pneumolysin (Ply)-deficient ST615 failed to develop any disease symptoms. Interestingly, the 2 strains did not differ in their ability to bind the immune complement or to undergo neutrophil-mediated phagocytosis. Upon comparative genomic analysis, we found higher within-ST sequence diversity in ST615 compared with ST306 and determined that ZmpA, ZmpD proteins, and IgA protease, were uniquely found in ST615. Using cell fractionation and cell contact-dependent assay, we made the unexpected finding that ST615 harbours the expression of two haemolytic variants of Ply: a cell-wall restricted fully haemolytic Ply, and a cytosolic pool of Ply void of any detectable haemolytic activity. This is the first time such a phenomenon has been described. We discuss the biological significance of our observation in relation to the aptitude of the pneumococcus for sustaining its human reservoir.
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Affiliation(s)
- Stavros Panagiotou
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK
| | - Chrispin Chaguza
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, CB10 1SA, UK
- Darwin College, University of Cambridge, Silver Street, Cambridge, CB3 9EU, UK
| | - Reham Yahya
- College of sciences and health professions, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
- King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Teerawit Audshasai
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK
| | - Murielle Baltazar
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK
| | - Lorenzo Ressel
- Department of Veterinary Pathology and Public Health, Institute of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, CH64 7TE, UK
| | - Shadia Khandaker
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK
| | - Mansoor Alsahag
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK
- Faculty of Applied Medical Sciences, Albaha University, Albaha, Kingdom of Saudi Arabia
| | - Tim J Mitchell
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Marc Prudhomme
- Université Paul Sabatier, Centre National de la Recherche Scientifique, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France
| | - Aras Kadioglu
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK.
| | - Marie Yang
- Department of Clinical Infection Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, The Ronald Ross Building, 8 West Derby St, Liverpool, L69 7BE, UK.
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13
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Interaction of Macrophages and Cholesterol-Dependent Cytolysins: The Impact on Immune Response and Cellular Survival. Toxins (Basel) 2020; 12:toxins12090531. [PMID: 32825096 PMCID: PMC7551085 DOI: 10.3390/toxins12090531] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/13/2020] [Accepted: 08/15/2020] [Indexed: 02/07/2023] Open
Abstract
Cholesterol-dependent cytolysins (CDCs) are key virulence factors involved in many lethal bacterial infections, including pneumonia, necrotizing soft tissue infections, bacterial meningitis, and miscarriage. Host responses to these diseases involve myeloid cells, especially macrophages. Macrophages use several systems to detect and respond to cholesterol-dependent cytolysins, including membrane repair, mitogen-activated protein (MAP) kinase signaling, phagocytosis, cytokine production, and activation of the adaptive immune system. However, CDCs also promote immune evasion by silencing and/or destroying myeloid cells. While there are many common themes between the various CDCs, each CDC also possesses specific features to optimally benefit the pathogen producing it. This review highlights host responses to CDC pathogenesis with a focus on macrophages. Due to their robust plasticity, macrophages play key roles in the outcome of bacterial infections. Understanding the unique features and differences within the common theme of CDCs bolsters new tools for research and therapy.
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Rezaei Javan R, Ramos-Sevillano E, Akter A, Brown J, Brueggemann AB. Prophages and satellite prophages are widespread in Streptococcus and may play a role in pneumococcal pathogenesis. Nat Commun 2019; 10:4852. [PMID: 31649284 PMCID: PMC6813308 DOI: 10.1038/s41467-019-12825-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 09/27/2019] [Indexed: 02/06/2023] Open
Abstract
Prophages (viral genomes integrated within a host bacterial genome) can confer various phenotypic traits to their hosts, such as enhanced pathogenicity. Here we analyse >1300 genomes of 70 different Streptococcus species and identify nearly 800 prophages and satellite prophages (prophages that do not encode their own structural components but rely on the bacterial host and another helper prophage for survival). We show that prophages and satellite prophages are widely distributed among streptococci in a structured manner, and constitute two distinct entities with little effective genetic exchange between them. Cross-species transmission of prophages is not uncommon. Furthermore, a satellite prophage is associated with virulence in a mouse model of Streptococcus pneumoniae infection. Our findings highlight the potential importance of prophages in streptococcal biology and pathogenesis. Prophages are viral genomes integrated within bacterial genomes. Here, Rezaei Javan et al. identify nearly 800 prophages and satellite prophages in > 1300 Streptococcus genomes, and show that a satellite prophage is associated with virulence in a mouse model of pneumococcal infection.
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Affiliation(s)
| | | | - Asma Akter
- Department of Medicine, Imperial College London, London, UK
| | - Jeremy Brown
- UCL Respiratory, Division of Medicine, University College London, London, UK
| | - Angela B Brueggemann
- Nuffield Department of Medicine, University of Oxford, Oxford, UK. .,Department of Medicine, Imperial College London, London, UK. .,Nuffield Department of Population Health, University of Oxford, Oxford, UK.
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15
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The Pneumococcal Surface Proteins PspA and PspC Sequester Host C4-Binding Protein To Inactivate Complement C4b on the Bacterial Surface. Infect Immun 2018; 87:IAI.00742-18. [PMID: 30323030 DOI: 10.1128/iai.00742-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 10/11/2018] [Indexed: 12/15/2022] Open
Abstract
Complement is a critical component of antimicrobial immunity. Various complement regulatory proteins prevent host cells from being attacked. Many pathogens have acquired the ability to sequester complement regulators from host plasma to evade complement attack. We describe here how Streptococcus pneumoniae adopts a strategy to prevent the formation of the C3 convertase C4bC2a by the rapid conversion of surface bound C4b and iC4b into C4dg, which remains bound to the bacterial surface but no longer forms a convertase complex. Noncapsular virulence factors on the pneumococcus are thought to facilitate this process by sequestering C4b-binding protein (C4BP) from host plasma. When S. pneumoniae D39 was opsonized with human serum, the larger C4 activation products C4b and iC4b were undetectable, but the bacteria were liberally decorated with C4dg and C4BP. With targeted deletions of either PspA or PspC, C4BP deposition was markedly reduced, and there was a corresponding reduction in C4dg and an increase in the deposition of C4b and iC4b. The effect was greatest when PspA and PspC were both knocked out. Infection experiments in mice indicated that the deletion of PspA and/or PspC resulted in the loss of bacterial pathogenicity. Recombinant PspA and PspC both bound serum C4BP, and both led to increased C4b and reduced C4dg deposition on S. pneumoniae D39. We conclude that PspA and PspC help the pneumococcus to evade complement attack by binding C4BP and so inactivating C4b.
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16
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Domenech M, Sempere J, de Miguel S, Yuste J. Combination of Antibodies and Antibiotics as a Promising Strategy Against Multidrug-Resistant Pathogens of the Respiratory Tract. Front Immunol 2018; 9:2700. [PMID: 30515172 PMCID: PMC6256034 DOI: 10.3389/fimmu.2018.02700] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 11/01/2018] [Indexed: 12/13/2022] Open
Abstract
The emergence of clinical isolates associated to multidrug resistance is a serious threat worldwide in terms of public health since complicates the success of the antibiotic treatment and the resolution of the infectious process. This is of great concern in pathogens affecting the lower respiratory tract as these infections are one of the major causes of mortality in children and adults. In most cases where the respiratory pathogen is associated to multidrug-resistance, antimicrobial concentrations both in serum and at the site of infection may be insufficient and the resolution of the infection depends on the interaction of the invading pathogen with the host immune response. The outcome of these infections largely depends on the susceptibility of the pathogen to the antibiotic treatment, although the humoral and cellular immune responses also play an important role in this process. Hence, prophylactic measures or even immunotherapy are alternatives against these multi-resistant pathogens. In this sense, specific antibodies and antibiotics may act concomitantly against the respiratory pathogen. Alteration of cell surface structures by antimicrobial drugs even at sub-inhibitory concentrations might result in greater exposure of microbial ligands that are normally hidden or hardly exposed. This alteration of the bacterial envelope may stimulate opsonization by natural and/or specific antibodies or even by host defense components, increasing the recognition of the microbial pathogen by circulating phagocytes. In this review we will explain the most relevant studies, where vaccination or the use of monoclonal antibodies in combination with antimicrobial treatment has demonstrated to be an alternative strategy to overcome the impact of multidrug resistance in respiratory pathogens.
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Affiliation(s)
- Mirian Domenech
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias, Madrid, Spain
| | - Julio Sempere
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias, Madrid, Spain
| | - Sara de Miguel
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias, Madrid, Spain
| | - Jose Yuste
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias, Madrid, Spain
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17
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Blood‒Brain Barrier Pathology and CNS Outcomes in Streptococcus pneumoniae Meningitis. Int J Mol Sci 2018; 19:ijms19113555. [PMID: 30423890 PMCID: PMC6275034 DOI: 10.3390/ijms19113555] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/05/2018] [Accepted: 11/09/2018] [Indexed: 12/20/2022] Open
Abstract
Streptococcus pneumoniae is a major meningitis-causing pathogen globally, bringing about significant morbidity and mortality, as well as long-term neurological sequelae in almost half of the survivors. Subsequent to nasopharyngeal colonisation and systemic invasion, translocation across the blood‒brain barrier (BBB) by S. pneumoniae is a crucial early step in the pathogenesis of meningitis. The BBB, which normally protects the central nervous system (CNS) from deleterious molecules within the circulation, becomes dysfunctional in S. pneumoniae invasion due to the effects of pneumococcal toxins and a heightened host inflammatory environment of cytokines, chemokines and reactive oxygen species intracranially. The bacteria‒host interplay within the CNS likely determines not only the degree of BBB pathological changes, but also host survival and the extent of neurological damage. This review explores the relationship between S. pneumoniae bacteria and the host inflammatory response, with an emphasis on the BBB and its roles in CNS protection, as well as both the acute and long-term pathogenesis of meningitis.
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18
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Weiser JN, Ferreira DM, Paton JC. Streptococcus pneumoniae: transmission, colonization and invasion. Nat Rev Microbiol 2018; 16:355-367. [PMID: 29599457 PMCID: PMC5949087 DOI: 10.1038/s41579-018-0001-8] [Citation(s) in RCA: 521] [Impact Index Per Article: 86.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Streptococcus pneumoniae has a complex relationship with its obligate human host. On the one hand, the pneumococci are highly adapted commensals, and their main reservoir on the mucosal surface of the upper airways of carriers enables transmission. On the other hand, they can cause severe disease when bacterial and host factors allow them to invade essentially sterile sites, such as the middle ear spaces, lungs, bloodstream and meninges. Transmission, colonization and invasion depend on the remarkable ability of S. pneumoniae to evade or take advantage of the host inflammatory and immune responses. The different stages of pneumococcal carriage and disease have been investigated in detail in animal models and, more recently, in experimental human infection. Furthermore, widespread vaccination and the resulting immune pressure have shed light on pneumococcal population dynamics and pathogenesis. Here, we review the mechanistic insights provided by these studies on the multiple and varied interactions of the pneumococcus and its host.
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19
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20
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Effect of decreased BCAA synthesis through disruption of ilvC gene on the virulence of Streptococcus pneumoniae. Arch Pharm Res 2017; 40:921-932. [PMID: 28735462 DOI: 10.1007/s12272-017-0931-0] [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: 04/18/2017] [Accepted: 07/17/2017] [Indexed: 10/19/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) is responsible for significant morbidity and mortality worldwide. It causes a variety of life-threatening infections such as pneumonia, bacteremia, and meningitis. In bacterial physiology, the metabolic pathway of branched-chain amino acids (BCAAs) plays an important role in virulence. Nonetheless, the function of IlvC, one of the enzymes involved in the biosynthesis of BCAAs, in S. pneumoniae remains unclear. Here, we demonstrated that downregulation of BCAA biosynthesis by ilvC ablation can diminish BCAA concentration and expression of pneumolysin (Ply) and LytA, and subsequently attenuate virulence. Infection with an ilvC mutant showed significantly reduced mortality and colonization in comparison with strain D39 (serotype 2, wild type), suggesting that ilvC can potentiate S. pneumoniae virulence due to adequate BCAA synthesis. Taken together, these results suggest that the function of ilvC in BCAA synthesis is essential for virulence factor and could play an important role in the pathogenesis of respiratory infections.
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21
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Andre GO, Converso TR, Politano WR, Ferraz LFC, Ribeiro ML, Leite LCC, Darrieux M. Role of Streptococcus pneumoniae Proteins in Evasion of Complement-Mediated Immunity. Front Microbiol 2017; 8:224. [PMID: 28265264 PMCID: PMC5316553 DOI: 10.3389/fmicb.2017.00224] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 01/31/2017] [Indexed: 12/14/2022] Open
Abstract
The complement system plays a central role in immune defense against Streptococcus pneumoniae. In order to evade complement attack, pneumococci have evolved a number of mechanisms that limit complement mediated opsonization and subsequent phagocytosis. This review focuses on the strategies employed by pneumococci to circumvent complement mediated immunity, both in vitro and in vivo. At last, since many of the proteins involved in interactions with complement components are vaccine candidates in different stages of validation, we explore the use of these antigens alone or in combination, as potential vaccine approaches that aim at elimination or drastic reduction in the ability of this bacterium to evade complement.
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Affiliation(s)
- Greiciely O Andre
- Laboratório de Biologia Celular e Molecular de Microrganismos, Universidade São Francisco Bragança Paulista, Brazil
| | - Thiago R Converso
- Centro de Biotecnologia, Instituto ButantanSão Paulo, Brazil; Programa de Pós-graduação Interunidades em Biotecnologia, Universidade de São PauloSão Paulo, Brazil
| | - Walter R Politano
- Laboratório de Biologia Celular e Molecular de Microrganismos, Universidade São Francisco Bragança Paulista, Brazil
| | - Lucio F C Ferraz
- Laboratório de Biologia Celular e Molecular de Microrganismos, Universidade São Francisco Bragança Paulista, Brazil
| | - Marcelo L Ribeiro
- Laboratório de Farmacologia, Universidade São Francisco Bragança Paulista, Brazil
| | | | - Michelle Darrieux
- Laboratório de Biologia Celular e Molecular de Microrganismos, Universidade São Francisco Bragança Paulista, Brazil
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22
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Wiedinger K, Pinho D, Bitsaktsis C. Utilization of cholera toxin B as a mucosal adjuvant elicits antibody-mediated protection against S. pneumoniae infection in mice. THERAPEUTIC ADVANCES IN VACCINES 2017; 5:15-24. [PMID: 28344805 DOI: 10.1177/2051013617691041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 12/07/2016] [Indexed: 11/16/2022]
Abstract
BACKGOUND The introduction of the pneumococcal conjugate and polysaccharide vaccines have been valuable tools for combating invasive pneumococcal infection in children and healthy adults. Despite the available vaccination strategies, pneumococcal pneumonia and associated diseases continue to cause substantial morbidity and mortality, particularly in individuals with chronic disease and ageing populations. Next-generation pneumococcal vaccines will need to be highly immunogenic across patient populations providing both mucosal and systemic protective immunity. Mucosal immunization is an effective strategy for stimulating the immune response at the site of pathogen entry while increasing systemic immunity. In this study we utilized intranasal immunization with pneumococcal surface protein A (PspA), in combination with the mucosal adjuvant cholera toxin B (CTB), to characterize the immune components providing protection against S. pneumoniae challenge. METHODS Mice were immunized intranasally with CTB and PspA individually, and in combination, followed by lethal bacterial challenge with S. pneumoniae, strain A66.1. Animals were monitored for survival and tested for lung bacterial burden, cytokine production as well as S. pneumoniae-specific antibody titer in mouse sera. The primary immunological contributor to the observed protection was confirmed by cytokine neutralization and serum passive transfer. RESULTS The combination of CTB and PspA provided complete protection against bacterial challenge, which coincided with a significant decrease in lung bacterial burden. Increases in the T-helper (Th) 1 cytokines, interferon (IFN)-γ and interleukin (IL)-2 were observed in the lung 24 h post-challenge while decreases in proinflammatory mediators IL-6 and tumor necrosis factor (TNF)-α were also recorded at the same time point. The adjuvanted PspA immunization induced significant titers of S. pneumoniae-specific antibody in the serum of mice prior to infection. Serum adoptive transfer passively protected animals against subsequent challenge while IFN-γ neutralization had no impact on the outcome of immunization, suggesting a primary role for antibody-mediated protection in the context of this immunization strategy. CONCLUSION Mucosal immunization with CTB and PspA induced a local cellular immune response and systemic humoral immunity which resulted in effective reduction of pulmonary bacterial burden and complete protection against S. pneumoniae challenge. While induction of the pleiotropic cytokine IFN-γ likely contributes to control of infection through activation of effector pathways, it was not required for protection. Instead, immunization with PspA and CTB-induced S. pneumoniae-specific antibodies in the serum prior to infection that were sufficient to protect against mucosal challenge.
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23
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Wilson R, Cohen JM, Reglinski M, Jose RJ, Chan WY, Marshall H, de Vogel C, Gordon S, Goldblatt D, Petersen FC, Baxendale H, Brown JS. Naturally Acquired Human Immunity to Pneumococcus Is Dependent on Antibody to Protein Antigens. PLoS Pathog 2017; 13:e1006137. [PMID: 28135322 PMCID: PMC5279798 DOI: 10.1371/journal.ppat.1006137] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/17/2016] [Indexed: 12/31/2022] Open
Abstract
Naturally acquired immunity against invasive pneumococcal disease (IPD) is thought to be dependent on anti-capsular antibody. However nasopharyngeal colonisation by Streptococcus pneumoniae also induces antibody to protein antigens that could be protective. We have used human intravenous immunoglobulin preparation (IVIG), representing natural IgG responses to S. pneumoniae, to identify the classes of antigens that are functionally relevant for immunity to IPD. IgG in IVIG recognised capsular antigen and multiple S. pneumoniae protein antigens, with highly conserved patterns between different geographical sources of pooled human IgG. Incubation of S. pneumoniae in IVIG resulted in IgG binding to the bacteria, formation of bacterial aggregates, and enhanced phagocytosis even for unencapsulated S. pneumoniae strains, demonstrating the capsule was unlikely to be the dominant protective antigen. IgG binding to S. pneumoniae incubated in IVIG was reduced after partial chemical or genetic removal of bacterial surface proteins, and increased against a Streptococcus mitis strain expressing the S. pneumoniae protein PspC. In contrast, depletion of type-specific capsular antibody from IVIG did not affect IgG binding, opsonophagocytosis, or protection by passive vaccination against IPD in murine models. These results demonstrate that naturally acquired protection against IPD largely depends on antibody to protein antigens rather than the capsule.
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Affiliation(s)
- Robert Wilson
- Centre for Inflammation and Tissue Repair, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Jonathan M. Cohen
- Infectious Diseases & Microbiology Unit, UCL Institute of Child Health, London, United Kingdom
| | - Mark Reglinski
- Centre for Inflammation and Tissue Repair, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Ricardo J. Jose
- Centre for Inflammation and Tissue Repair, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Win Yan Chan
- Centre for Inflammation and Tissue Repair, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Helina Marshall
- Centre for Inflammation and Tissue Repair, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Corné de Vogel
- Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Stephen Gordon
- Respiratory Infection Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - David Goldblatt
- Institute of Child Health, University College London, London, United Kingdom
| | | | - Helen Baxendale
- Clinical Immunology Department, Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom
| | - Jeremy S. Brown
- Centre for Inflammation and Tissue Repair, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
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Choline Binding Proteins from Streptococcus pneumoniae: A Dual Role as Enzybiotics and Targets for the Design of New Antimicrobials. Antibiotics (Basel) 2016; 5:antibiotics5020021. [PMID: 27314398 PMCID: PMC4929436 DOI: 10.3390/antibiotics5020021] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 05/04/2016] [Accepted: 05/16/2016] [Indexed: 12/20/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is an important pathogen responsible for acute invasive and non-invasive infections such as meningitis, sepsis and otitis media, being the major cause of community-acquired pneumonia. The fight against pneumococcus is currently hampered both by insufficient vaccine coverage and by rising antimicrobial resistances to traditional antibiotics, making necessary the research on novel targets. Choline binding proteins (CBPs) are a family of polypeptides found in pneumococcus and related species, as well as in some of their associated bacteriophages. They are characterized by a structural organization in two modules: a functional module (FM), and a choline-binding module (CBM) that anchors the protein to the choline residues present in the cell wall through non-covalent interactions. Pneumococcal CBPs include cell wall hydrolases, adhesins and other virulence factors, all playing relevant physiological roles for bacterial viability and virulence. Moreover, many pneumococcal phages also make use of hydrolytic CBPs to fulfill their infectivity cycle. Consequently, CBPs may play a dual role for the development of novel antipneumococcal drugs, both as targets for inhibitors of their binding to the cell wall and as active cell lytic agents (enzybiotics). In this article, we review the current state of knowledge about host- and phage-encoded pneumococcal CBPs, with a special focus on structural issues, together with their perspectives for effective anti-infectious treatments.
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25
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Escolano-Martínez MS, Domenech A, Yuste J, Cercenado MI, Ardanuy C, Liñares J, de la Campa AG, Martin-Galiano AJ. DiiA is a novel dimorphic cell wall protein of Streptococcus pneumoniae involved in invasive disease. J Infect 2016; 73:71-81. [PMID: 27105656 DOI: 10.1016/j.jinf.2016.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 04/06/2016] [Accepted: 04/11/2016] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Many outer multidomain proteins play fundamental virulent roles in an allele-dependent manner. We aimed to investigate the influence of the outer SP1992 protein, here renamed DiiA (Dimorphic invasion-involved A), in pneumococcal disease. METHODS The presence and type of diiA allele was screened by PCR in 560 clinical isolates. Isogenic mutants carrying progressive diiA deletions were constructed and checked in mouse models of infection. DiiA binding to human molecules was carried out by surface plasmon resonance. RESULTS The diiA gene is exclusive of Streptococcus pneumoniae and included in the core genome. DiiA variants contain one or two imperfect repeats (R1 and R2), an unstructured region and a cell-wall anchor domain. Clonal complexes carrying both repeats were associated with invasive disease, while those carrying R2 preferentially caused non-invasive syndromes in patients with underlying risk factors. Mutants lacking both repeats were less efficient in nasopharyngeal colonization and dissemination from lungs. Moreover, the ΔdiiA defective strain suffered a severe impairment in bacterial proliferation in blood. Purified DiiA bound to collagen and lactoferrin with high affinity. CONCLUSIONS DiiA is a distinctive pneumococcal virulence factor contributing to colonization and long-term invasion in this pathogen.
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Affiliation(s)
- María S Escolano-Martínez
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Carretera a Pozuelo, km 2.2, Majadahonda, 28220 Madrid, Spain
| | - Arnau Domenech
- CIBER de Enfermedades Respiratorias (CIBERES), Spain; Servicio de Microbiología, Hospital Universitari de Bellvitge, Universitat de Barcelona, IDIBELL, Feixa Llarga, sn. L'Hospitalet de Llobregat, 08907 Barcelona, Spain
| | - José Yuste
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Carretera a Pozuelo, km 2.2, Majadahonda, 28220 Madrid, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Spain
| | - María I Cercenado
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Carretera a Pozuelo, km 2.2, Majadahonda, 28220 Madrid, Spain
| | - Carmen Ardanuy
- CIBER de Enfermedades Respiratorias (CIBERES), Spain; Servicio de Microbiología, Hospital Universitari de Bellvitge, Universitat de Barcelona, IDIBELL, Feixa Llarga, sn. L'Hospitalet de Llobregat, 08907 Barcelona, Spain
| | - Josefina Liñares
- CIBER de Enfermedades Respiratorias (CIBERES), Spain; Servicio de Microbiología, Hospital Universitari de Bellvitge, Universitat de Barcelona, IDIBELL, Feixa Llarga, sn. L'Hospitalet de Llobregat, 08907 Barcelona, Spain
| | - Adela G de la Campa
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Carretera a Pozuelo, km 2.2, Majadahonda, 28220 Madrid, Spain; Presidencia, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Antonio J Martin-Galiano
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Carretera a Pozuelo, km 2.2, Majadahonda, 28220 Madrid, Spain.
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26
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Zhang H, Kang L, Yao H, He Y, Wang X, Xu W, Song Z, Yin Y, Zhang X. Streptococcus pneumoniae Endopeptidase O (PepO) Elicits a Strong Innate Immune Response in Mice via TLR2 and TLR4 Signaling Pathways. Front Cell Infect Microbiol 2016; 6:23. [PMID: 26973817 PMCID: PMC4770053 DOI: 10.3389/fcimb.2016.00023] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 02/12/2016] [Indexed: 11/13/2022] Open
Abstract
Interaction between virulence factors of Streptococcus pneumoniae and innate immune receptors elicits host responses through specific signaling pathways during infection. Insights into the signaling events may provide a better knowledge of the starting events for host-pathogen interaction. Here we demonstrated a significant induction of innate immune response elicited by recombinant S. pneumoniae endopeptidase O (rPepO), a newer pneumococcal virulence protein, both in vivo and in vitro. Intratracheal instillation of rPepO protein resulted in significant increase of cytokines production and neutrophils infiltration in mouse lungs. TLR2 or TLR4 deficient mice subjected to rPepO treatment showed decreased cytokines production, reduced neutrophils infiltration and intensified tissue injury as compared with WT mice. Upon stimulation, cytokines TNF-α, IL-6, CXCL1, and CXCL10 were produced by peritoneal exudate macrophages (PEMs) in a TLR2 and TLR4 dependent manner. rPepO-induced cytokines production was markedly decreased in TLR2 or TLR4 deficient PEMs. Further study revealed that cytokines induction relied on the rapid phosphorylation of p38, Akt and p65, not the activation of ERK or JNK. While in TLR2 or TLR4 deficient PEMs the activation of p65 was undetectable. Taken together, these results indicate for the first time that the newer pneumococcal virulence protein PepO activates host innate immune response partially through TLR2 and TLR4 signaling pathways.
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Affiliation(s)
- Hong Zhang
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Lihua Kang
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Hua Yao
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Yujuan He
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Xiaofang Wang
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Wenchun Xu
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Zhixin Song
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Yibing Yin
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
| | - Xuemei Zhang
- Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University Chongqing, China
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Morales M, Martín-Galiano AJ, Domenech M, García E. Insights into the Evolutionary Relationships of LytA Autolysin and Ply Pneumolysin-Like Genes in Streptococcus pneumoniae and Related Streptococci. Genome Biol Evol 2015; 7:2747-61. [PMID: 26349755 PMCID: PMC4607534 DOI: 10.1093/gbe/evv178] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is a major human pathogen. The main pneumococcal autolysin LytA and the pneumolysin Ply are two of the bacterium's most important virulence factors. The lytA- and ply-related genes are also found in other streptococci of the Mitis group (SMG). The precise characteristics of the lytA-related-but not the ply-related-genes of SMG and their prophages have been previously described. A search of the more than 400 SMG genomic sequences available in public databases (ca. 300 for S. pneumoniae), showed Streptococcus pseudopneumoniae IS7493 to harbor four ply-related genes, two of which (plyA and plyB) have 98% identical nucleotides. The plyA homolog of S. pseudopneumoniae is conserved in all S. pneumoniae strains, and seems to be included in a pathogenicity island together with the lytA gene. However, only nonencapsulated S. pneumoniae strains possess a plyB gene, which is part of an integrative and conjugative element. Notably, the existence of a bacterial lytA-related gene in a genome is linked to the presence of plyA and vice versa. The present analysis also shows there are eight main types of plyA-lytA genomic islands. A possible stepwise scenario for the evolution of the plyA-lytA island in S. pneumoniae is proposed.
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Affiliation(s)
- María Morales
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain Unidad de Genética Bacteriana, Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Antonio J Martín-Galiano
- Unidad de Genética Bacteriana, Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Madrid, Spain Centro Nacional de Microbiología, ISCIII, Majadahonda, Madrid, Spain
| | - Mirian Domenech
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain Unidad de Genética Bacteriana, Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Ernesto García
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain Unidad de Genética Bacteriana, Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
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Importance of bacterial replication and alveolar macrophage-independent clearance mechanisms during early lung infection with Streptococcus pneumoniae. Infect Immun 2015; 83:1181-9. [PMID: 25583525 DOI: 10.1128/iai.02788-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although the importance of alveolar macrophages for host immunity during early Streptococcus pneumoniae lung infection is well established, the contribution and relative importance of other innate immunity mechanisms and of bacterial factors are less clear. We have used a murine model of S. pneumoniae early lung infection with wild-type, unencapsulated, and para-amino benzoic acid auxotroph mutant TIGR4 strains to assess the effects of inoculum size, bacterial replication, capsule, and alveolar macrophage-dependent and -independent clearance mechanisms on bacterial persistence within the lungs. Alveolar macrophage-dependent and -independent (calculated indirectly) clearance half-lives and bacterial replication doubling times were estimated using a mathematical model. In this model, after infection with a high-dose inoculum of encapsulated S. pneumoniae, alveolar macrophage-independent clearance mechanisms were dominant, with a clearance half-life of 24 min compared to 135 min for alveolar macrophage-dependent clearance. In addition, after a high-dose inoculum, successful lung infection required rapid bacterial replication, with an estimated S. pneumoniae doubling time of 16 min. The capsule had wide effects on early lung clearance mechanisms, with reduced half-lives of 14 min for alveolar macrophage-independent and 31 min for alveolar macrophage-dependent clearance of unencapsulated bacteria. In contrast, with a lower-dose inoculum, the bacterial doubling time increased to 56 min and the S. pneumoniae alveolar macrophage-dependent clearance half-life improved to 42 min and was largely unaffected by the capsule. These data demonstrate the large effects of bacterial factors (inoculum size, the capsule, and rapid replication) and alveolar macrophage-independent clearance mechanisms during early lung infection with S. pneumoniae.
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Pleiotropic effects of cell wall amidase LytA on Streptococcus pneumoniae sensitivity to the host immune response. Infect Immun 2014; 83:591-603. [PMID: 25404032 DOI: 10.1128/iai.02811-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The complement system is a key component of the host immune response for the recognition and clearance of Streptococcus pneumoniae. In this study, we demonstrate that the amidase LytA, the main pneumococcal autolysin, inhibits complement-mediated immunity independently of effects on pneumolysin by a complex process of impaired complement activation, increased binding of complement regulators, and direct degradation of complement C3. The use of human sera depleted of either C1q or factor B confirmed that LytA prevented activation of both the classical and alternative pathways, whereas pneumolysin inhibited only the classical pathway. LytA prevented binding of C1q and the acute-phase protein C-reactive protein to S. pneumoniae, thereby reducing activation of the classical pathway on the bacterial surface. In addition, LytA increased recruitment of the complement downregulators C4BP and factor H to the pneumococcal cell wall and directly cleaved C3b and iC3b to generate degradation products. As a consequence, C3b deposition and phagocytosis increased in the absence of LytA and were markedly enhanced for the lytA ply double mutant, confirming that a combination of LytA and Ply is essential for the establishment of pneumococcal pneumonia and sepsis in a murine model of infection. These data demonstrate that LytA has pleiotropic effects on complement activation, a finding which, in combination with the effects of pneumolysin on complement to assist with pneumococcal complement evasion, confirms a major role of both proteins for the full virulence of the microorganism during septicemia.
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Cole J, Aberdein J, Jubrail J, Dockrell DH. The role of macrophages in the innate immune response to Streptococcus pneumoniae and Staphylococcus aureus: mechanisms and contrasts. Adv Microb Physiol 2014; 65:125-202. [PMID: 25476766 DOI: 10.1016/bs.ampbs.2014.08.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Macrophages are critical mediators of innate immune responses against bacteria. The Gram-positive bacteria Streptococcus pneumoniae and Staphylococcus aureus express a range of virulence factors, which challenge macrophages' immune competence. We review how macrophages respond to this challenge. Macrophages employ a range of strategies to phagocytose and kill each pathogen. When the macrophages capacity to clear bacteria is overwhelmed macrophages play important roles in orchestrating the inflammatory response through pattern recognition receptor-mediated responses. Macrophages also ensure the inflammatory response is tightly constrained, to avoid tissue damage, and play an important role in downregulating the inflammatory response once initial bacterial replication is controlled.
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Affiliation(s)
- Joby Cole
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - Jody Aberdein
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - Jamil Jubrail
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - David H Dockrell
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom.
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Pneumolysin activates macrophage lysosomal membrane permeabilization and executes apoptosis by distinct mechanisms without membrane pore formation. mBio 2014; 5:e01710-14. [PMID: 25293758 PMCID: PMC4196231 DOI: 10.1128/mbio.01710-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Intracellular killing of Streptococcus pneumoniae is complemented by induction of macrophage apoptosis. Here, we show that the toxin pneumolysin (PLY) contributes both to lysosomal/phagolysosomal membrane permeabilization (LMP), an upstream event programing susceptibility to apoptosis, and to apoptosis execution via a mitochondrial pathway, through distinct mechanisms. PLY is necessary but not sufficient for the maximal induction of LMP and apoptosis. PLY's ability to induce both LMP and apoptosis is independent of its ability to form cytolytic pores and requires only the first three domains of PLY. LMP involves TLR (Toll-like receptor) but not NLRP3/ASC (nucleotide-binding oligomerization domain [Nod]-like receptor family, pyrin domain-containing protein 3/apoptosis-associated speck-like protein containing a caspase recruitment domain) signaling and is part of a PLY-dependent but phagocytosis-independent host response that includes the production of cytokines, including interleukin-1 beta (IL-1β). LMP involves progressive and selective permeability to 40-kDa but not to 250-kDa fluorescein isothiocyanate (FITC)-labeled dextran, as PLY accumulates in the cytoplasm. In contrast, the PLY-dependent execution of apoptosis requires phagocytosis and is part of a host response to intracellular bacteria that also includes NO generation. In cells challenged with PLY-deficient bacteria, reconstitution of LMP using the lysomotrophic detergent LeuLeuOMe favored cell necrosis whereas PLY reconstituted apoptosis. The results suggest that PLY contributes to macrophage activation and cytokine production but also engages LMP. Following bacterial phagocytosis, PLY triggers apoptosis and prevents macrophage necrosis as a component of a broad-based antimicrobial strategy. This illustrates how a key virulence factor can become the focus of a multilayered and coordinated innate response by macrophages, optimizing pathogen clearance and limiting inflammation. Importance: Streptococcus pneumoniae, the commonest cause of bacterial pneumonia, expresses the toxin pneumolysin, which can make holes in cell surfaces, causing tissue damage. Macrophages, resident immune cells essential for responses to bacteria in tissues, activate a program of cell suicide called apoptosis, maximizing bacterial clearance and limiting harmful inflammation. We examined pneumolysin's role in activating this response. We demonstrate that pneumolysin did not directly form holes in cells to trigger apoptosis and show that pneumolysin has two distinct roles which require only part of the molecule. Pneumolysin and other bacterial factors released by bacteria that have not been eaten by macrophages activate macrophages to release inflammatory factors but also make the cell compartment containing ingested bacteria leaky. Once inside the cell, pneumolysin ensures that the bacteria activate macrophage apoptosis, rather than necrosis, enhancing bacterial killing and limiting inflammation. This dual response to pneumolysin is critical for an effective immune response to S. pneumoniae.
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Wade KR, Hotze EM, Briles DE, Tweten RK. Mouse, but not human, ApoB-100 lipoprotein cholesterol is a potent innate inhibitor of Streptococcus pneumoniae pneumolysin. PLoS Pathog 2014; 10:e1004353. [PMID: 25188225 PMCID: PMC4154877 DOI: 10.1371/journal.ppat.1004353] [Citation(s) in RCA: 15] [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: 06/12/2014] [Accepted: 07/18/2014] [Indexed: 11/19/2022] Open
Abstract
Streptococcus pneumoniae produces the pore-forming toxin pneumolysin (PLY), which is a member of the cholesterol-dependent cytolysin (CDC) family of toxins. The CDCs recognize and bind the 3β-hydroxyl group of cholesterol at the cell surface, which initiates membrane pore formation. The cholesterol transport lipoproteins, which carry cholesterol in their outer monolayer, are potential off-pathway binding targets for the CDCs and are present at significant levels in the serum and the interstitial spaces of cells. Herein we show that cholesterol carried specifically by the ApoB-100-containing lipoprotein particles (CH-ApoB-100) in the mouse, but not that carried by human or guinea pig particles, is a potent inhibitor of the PLY pore-forming mechanism. Cholesterol present in the outer monolayer of mouse ApoB-100 particles is recognized and bound by PLY, which stimulates premature assembly of the PLY oligomeric complex thereby inactivating PLY. These studies further suggest that the vast difference in the inhibitory capacity of mouse CH-ApoB-100 and that of the human and the guinea pig is due to differences in the presentation of cholesterol in the outer monolayer of their ApoB-100 particles. Therefore mouse CH-ApoB-100 represents a significant innate CDC inhibitor that is absent in humans, which may underestimate the contribution of CDCs to human disease when utilizing mouse models of disease.
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Affiliation(s)
- Kristin R. Wade
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Eileen M. Hotze
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - David E. Briles
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Rodney K. Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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Martín-Galiano AJ, Yuste J, Cercenado MI, de la Campa AG. Inspecting the potential physiological and biomedical value of 44 conserved uncharacterised proteins of Streptococcus pneumoniae. BMC Genomics 2014; 15:652. [PMID: 25096389 PMCID: PMC4143570 DOI: 10.1186/1471-2164-15-652] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 07/21/2014] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The major Gram-positive coccoid pathogens cause similar invasive diseases and show high rates of antimicrobial resistance. Uncharacterised proteins shared by these organisms may be involved in virulence or be targets for antimicrobial therapy. RESULTS Forty four uncharacterised proteins from Streptococcus pneumoniae with homologues in Enterococcus faecalis and/or Staphylococcus aureus were selected for analysis. These proteins showed differences in terms of sequence conservation and number of interacting partners. Twenty eight of these proteins were monodomain proteins and 16 were modular, involving domain combinations and, in many cases, predicted unstructured regions. The genes coding for four of these 44 proteins were essential. Genomic and structural studies showed one of the four essential genes to code for a promising antibacterial target. The strongest impact of gene removal was on monodomain proteins showing high sequence conservation and/or interactions with many other proteins. Eleven out of 40 knockouts (one for each gene) showed growth delay and 10 knockouts presented a chaining phenotype. Five of these chaining mutants showed a lack of putative DNA-binding proteins. This suggest this phenotype results from a loss of overall transcription regulation. Five knockouts showed defective autolysis in response to penicillin and vancomycin, and attenuated virulence in an animal model of sepsis. CONCLUSIONS Uncharacterised proteins make up a reservoir of polypeptides of different physiological importance and biomedical potential. A promising antibacterial target was identified. Five of the 44 examined proteins seemed to be virulence factors.
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Affiliation(s)
- Antonio J Martín-Galiano
- />Centro Nacional de Microbiología and CIBERES (CIBER de Enfermedades Respiratorias), Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - José Yuste
- />Centro Nacional de Microbiología and CIBERES (CIBER de Enfermedades Respiratorias), Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - María I Cercenado
- />Centro Nacional de Microbiología and CIBERES (CIBER de Enfermedades Respiratorias), Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Adela G de la Campa
- />Centro Nacional de Microbiología and CIBERES (CIBER de Enfermedades Respiratorias), Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
- />Presidencia, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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Role of capsule and suilysin in mucosal infection of complement-deficient mice with Streptococcus suis. Infect Immun 2014; 82:2460-71. [PMID: 24686060 DOI: 10.1128/iai.00080-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Virulent Streptococcus suis serotype 2 strains are invasive extracellular bacteria causing septicemia and meningitis in piglets and humans. One objective of this study was to elucidate the function of complement in innate immune defense against S. suis. Experimental infection of wild-type (WT) and C3(-/-) mice demonstrated for the first time that the complement system protects naive mice against invasive mucosal S. suis infection. S. suis WT but not an unencapsulated mutant caused mortality associated with meningitis and other pathologies in C3(-/-) mice. The capsule contributed also substantially to colonization of the upper respiratory tract. Experimental infection of C3(-/-) mice with a suilysin mutant indicated that suilysin expression facilitated an early disease onset and the pathogenesis of meningitis. Flow cytometric analysis revealed C3 antigen deposition on the surface of ca. 40% of S. suis WT bacteria after opsonization with naive WT mouse serum, although to a significantly lower intensity than on the unencapsulated mutant. Ex vivo multiplication in murine WT and C3(-/-) blood depended on capsule but not suilysin expression. Interestingly, S. suis invasion of inner organs was also detectable in C5aR(-/-) mice, suggesting that chemotaxis and activation of immune cells via the anaphylatoxin receptor C5aR is, in addition to opsonization, a further important function of the complement system in defense against mucosal S. suis infection. In conclusion, we unequivocally demonstrate here the importance of complement against mucosal S. suis serotype 2 infection and that the capsule of this pathogen is also involved in escape from complement-independent immunity.
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Küng E, Coward WR, Neill DR, Malak HA, Mühlemann K, Kadioglu A, Hilty M, Hathaway LJ. The pneumococcal polysaccharide capsule and pneumolysin differentially affect CXCL8 and IL-6 release from cells of the upper and lower respiratory tract. PLoS One 2014; 9:e92355. [PMID: 24664110 PMCID: PMC3963895 DOI: 10.1371/journal.pone.0092355] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 02/20/2014] [Indexed: 11/19/2022] Open
Abstract
The polysaccharide capsule and pneumolysin toxin are major virulence factors of the human bacterial pathogen Streptococcus pneumoniae. Colonization of the nasopharynx is asymptomatic but invasion of the lungs can result in invasive pneumonia. Here we show that the capsule suppresses the release of the pro-inflammatory cytokines CXCL8 (IL-8) and IL-6 from the human pharyngeal epithelial cell line Detroit 562. Release of both cytokines was much less from human bronchial epithelial cells (iHBEC) but levels were also affected by capsule. Pneumolysin stimulates CXCL8 release from both cell lines. Suppression of CXCL8 homologue (CXCL2/MIP-2) release by the capsule was also observed in vivo during intranasal colonization of mice but was only discernable in the absence of pneumolysin. When pneumococci were administered intranasally to mice in a model of long term, stable nasopharyngeal carriage, encapsulated S. pneumoniae remained in the nasopharynx whereas the nonencapsulated pneumococci disseminated into the lungs. Pneumococcal capsule plays a role not only in protection from phagocytosis but also in modulation of the pro-inflammatory immune response in the respiratory tract.
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Affiliation(s)
- Eliane Küng
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - William R. Coward
- Nottingham Respiratory Biomedical Research Unit, Clinical Sciences Building, Nottingham City Campus, Nottingham, United Kingdom
| | - Daniel R. Neill
- Clinical Infection, Microbiology and Immunology, Institute of Infection & Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Hesham A. Malak
- Clinical Infection, Microbiology and Immunology, Institute of Infection & Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Kathrin Mühlemann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Aras Kadioglu
- Clinical Infection, Microbiology and Immunology, Institute of Infection & Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Markus Hilty
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Department of Infectious Diseases, University Hospital, Bern, Switzerland
| | - Lucy J. Hathaway
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- * E-mail:
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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.
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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.
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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
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Schachern PA, Tsuprun V, Goetz S, Cureoglu S, Juhn SK, Briles DE, Paparella MM, Ferrieri P. Viability and virulence of pneumolysin, pneumococcal surface protein A, and pneumolysin/pneumococcal surface protein A mutants in the ear. JAMA Otolaryngol Head Neck Surg 2013; 139:937-43. [PMID: 24051749 DOI: 10.1001/jamaoto.2013.4104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Understanding how pneumococcal proteins affect the pathology of the middle ear and inner ear is important for the development of new approaches to prevent otitis media and its complications. OBJECTIVES To determine the viability and virulence of Streptococcus pneumoniae mutants deficient in pneumolysin (Ply-) and pneumococcal surface protein A (PspA-) in the chinchilla middle ear. DESIGN Bullae of chinchillas were inoculated bilaterally with wild-type (Wt), Ply-, PspA-, and Ply-/PspA- strains. Bacterial colony-forming units (CFUs) in middle ear effusions were counted at 48 hours. The CFUs of the PspA- group were also counted at 6 to 36 hours after inoculation. Temporal bone histopathological results were compared. SETTING AND PARTICIPANTS Twenty-seven chinchillas in an academic research laboratory. EXPOSURE Chinchilla middle ears were inoculated with S pneumoniae to produce sufficient volumes of effusions and noticeable histopathological changes in the ears. MAIN OUTCOMES AND MEASURES The CFU counts in the middle ear effusions and histopathological changes were compared to determine the effect of pneumococcal protein mutations on chinchilla ears. RESULTS At 48 hours, CFUs in middle ears were increased for the Wt and Ply-/PspA- strains, but Ply- remained near inoculum level. No bacteria were detected in the PspA- group. The CFUs of PspA- decreased over time to a low level at 30 to 36 hours. In vitro, PspA- in Todd-Hewitt broth showed an increase in bacterial growth of 2 logs at 43 hours, indicating PspA- susceptibility to host defenses in vivo. The PspA- and Ply- groups had fewer pathologic findings than the Wt or Ply-/PspA- groups. Histopathological analysis showed significant differences in the number of bacteria in the scala tympani in the Wt group compared with the Ply-, PspA-, and Ply-/PspA- groups. The PspA- strain was the least virulent. CONCLUSIONS AND RELEVANCE The PspA- mutant was much less viable and less virulent in the ear than the Wt, Ply-, and Ply-/PspA- strains. There was no significant attenuation in the viability and virulence of the Ply-/PspA- mutant compared with the Wt or single mutants. The viability and virulence of pneumococcal mutants seemed to be protein and organ specific.
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Ricci S, Gerlini A, Pammolli A, Chiavolini D, Braione V, Tripodi SA, Colombari B, Blasi E, Oggioni MR, Peppoloni S, Pozzi G. Contribution of different pneumococcal virulence factors to experimental meningitis in mice. BMC Infect Dis 2013; 13:444. [PMID: 24059458 PMCID: PMC3848944 DOI: 10.1186/1471-2334-13-444] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/13/2013] [Indexed: 11/28/2022] Open
Abstract
Background Pneumococcal meningitis (PM) is a life-threatening disease with a high case-fatality rate and elevated risk for serious neurological sequelae. In this study, we investigated the contribution of three major virulence factors of Streptococcus pneumoniae, the capsule, pneumococcal surface protein A (PspA) and C (PspC), to the pathogenesis of experimental PM. Methods Mice were challenged by the intracranial route with the serotype 4 TIGR4 strain (wt) and three isogenic mutants devoid of PspA, PspC, and the capsule. Survival, bacterial counts, and brain histology were carried out. To study the interaction between S. pneumoniae mutants and microglia, phagocytosis and survival experiments were performed using the BV2 mouse microglial cell line. Results Virulence of the PspC mutant was comparable to that of TIGR4. In contrast, survival of animals challenged with the PspA mutant was significantly increased compared with the wt, and the mutant was also impaired at replicating in the brain and blood of infected mice. Brain histology indicated that all strains, except for the unencapsulated mutant, caused PM. Analysis of inflammation and damage in the brain of mice infected with TIGR4 or its unencapsulated mutant demonstrated that the rough strain was unable to induce inflammation and neuronal injury, even at high challenge doses. Results with BV2 cells showed no differences in phagocytic uptake between wt and mutants. In survival assays, however, the PspA mutant showed significantly reduced survival in microglia compared with the wt. Conclusions PspA contributed to PM pathogenesis possibly by interacting with microglia at early infection stages, while PspC had limited importance in the disease. The rough mutant did not cause brain inflammation, neuronal damage or mouse death, strengthening the key role of the capsule in PM.
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Affiliation(s)
- Susanna Ricci
- Department of Medical Biotechnologies, Laboratory of Molecular Microbiology and Biotechnology (LA,M,M,B,), University of Siena and Siena University Hospital, Siena 53100, Italy.
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Los FCO, Randis TM, Aroian RV, Ratner AJ. Role of pore-forming toxins in bacterial infectious diseases. Microbiol Mol Biol Rev 2013; 77:173-207. [PMID: 23699254 PMCID: PMC3668673 DOI: 10.1128/mmbr.00052-12] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.
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Affiliation(s)
| | - Tara M. Randis
- Department of Pediatrics, Columbia University, New York, New York, USA
| | - Raffi V. Aroian
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, USA
| | - Adam J. Ratner
- Department of Pediatrics, Columbia University, New York, New York, USA
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Streptococcus pneumoniae capsular serotype invasiveness correlates with the degree of factor H binding and opsonization with C3b/iC3b. Infect Immun 2012; 81:354-63. [PMID: 23147038 DOI: 10.1128/iai.00862-12] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Different capsular serotypes of Streptococcus pneumoniae vary markedly in their ability to cause invasive infection, but the reasons why are not known. As immunity to S. pneumoniae infection is highly complement dependent, variations in sensitivity to complement between S. pneumoniae capsular serotypes could affect invasiveness. We have used 20 capsule-switched variants of strain TIGR4 to investigate whether differences in the binding of the alternative pathway inhibitor factor H (FH) could be one mechanism causing variations in complement resistance and invasive potential between capsular serotypes. Flow cytometry assays were used to assess complement factor binding and complement-dependent neutrophil association for the TIGR4 capsule-switched strains. FH binding varied with the serotype and inversely correlated with the results of factor B binding, C3b/iC3b deposition, and neutrophil association. Differences between strains in FH binding were lost when assays were repeated with pspC mutant strains, and loss of PspC also reduced differences in C3b/iC3b deposition between strains. Median FH binding was high in capsule-switched mutant strains expressing more invasive serotypes, and a principal component analysis demonstrated a strong correlation between serotype invasiveness, high FH binding, and resistance to complement and neutrophil association. Further data obtained with 33 clinical strains also demonstrated that FH binding negatively correlated with C3b/iC3b deposition and that median FH binding was high in strains expressing more invasive serotypes. These data suggest that variations in complement resistance between S. pneumoniae strains and the association of a serotype with invasiveness could be related to capsular serotype effects on FH binding.
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Macrolides and β-lactam antibiotics enhance C3b deposition on the surface of multidrug-resistant Streptococcus pneumoniae strains by a LytA autolysin-dependent mechanism. Antimicrob Agents Chemother 2012; 56:5534-40. [PMID: 22890762 DOI: 10.1128/aac.01470-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The emergence of Streptococcus pneumoniae strains displaying high levels of multidrug resistance is of great concern worldwide and a serious threat for the outcome of the infection. Modifications of the bacterial envelope by antibiotics may assist the recognition and clearance of the pathogen by the host immune system. Recognition of S. pneumoniae resistant strains by the complement component C3b was increased in the presence of specific anti-pneumococcal antibodies and subinhibitory concentrations of different macrolides and β-lactam antibiotics for all the strains investigated. However, C3b levels were unchanged in the presence of serum containing specific antibodies and sub-MICs of levofloxacin. To investigate whether LytA, the main cell wall hydrolase of S. pneumoniae, might be involved in this process, lytA-deficient mutants were constructed. In the presence of antibiotics, loss of LytA was not associated with enhanced C3b deposition on the pneumococcal surface, which confirms the importance of LytA in this interaction. The results of this study offer new insights into the development of novel therapeutic strategies using certain antibiotics by increasing the efficacy of the host immune response to efficiently recognize pneumococcal resistant strains.
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Shivshankar P. Modulation of bacterial pathogenesis by oppressive aging factors: insights into host-pneumococcal interaction strategies. ISRN INFLAMMATION 2012; 2012:267101. [PMID: 24049644 PMCID: PMC3765745 DOI: 10.5402/2012/267101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 03/20/2012] [Indexed: 01/20/2023]
Abstract
Streptococcus pneumonia, (Spn, the pneumococcus), is the leading cause of community-acquired pneumonia (CAP) and is responsible for 15–40% deaths in the elderly worldwide. A primed inflammatory status is a significant risk factor for the increased severity of infectious diseases among the elderly (≥65 years of age). Studies have shown that expression of host receptors that the pneumococci bind to invade the tissues are increased thereby increasing the susceptibility to pneumococcal challenge in aged mice. Cellular senescence, an age-related phenomenon that leads to cell cycle arrest may also contribute to increased inflammation in aged mice. Evidence of cellular senescence in aged lungs of humans and mice adds credits to the concept of inflammaging and enhanced bacterial ligands expression during aging. Furthermore, cell senescence has been shown to occur in age-associated lung pathologies such as idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) that may predispose the elderly to pathogenic assaults, including S. pneumoniae. This review highlights the aspects of: chronic inflammation in the aged population; contribution of cellular senescence to age-associated inflammation and their impact on host receptor expression; and, increased susceptibility of fibrosis and emphysematous lesions-bearing lungs to microbial infections.
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Affiliation(s)
- Pooja Shivshankar
- Division of Cardiology, Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Fhb, a novel factor H-binding surface protein, contributes to the antiphagocytic ability and virulence of Streptococcus suis. Infect Immun 2012; 80:2402-13. [PMID: 22526676 DOI: 10.1128/iai.06294-11] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Streptococcus suis serotype 2 is a Gram-positive bacterium that causes sepsis and meningitis in piglets and humans. The mechanisms of S. suis serotype 2 invasive disease are not well understood. The surface proteins of pathogens usually play important roles in infection and bacterium-host interactions. Here, we identified a novel surface protein that contributed significantly to the virulence of S. suis serotype 2 in a piglet infection model. This protein showed little similarity to other reported proteins and exhibited strong binding activity to human factor H (hFH). It was designated Fhb (factor H-binding protein). The fhb genes found in S. suis serotypes 1, 2, 4, 7, and 9 exhibited molecular polymorphism. Fhb possessed two proline-rich repeat sequences and XPZ domains, and one repeat sequence exhibited a high homology to Bac, an IgA-binding protein of Streptococcus agalactiae. Evidence strongly indicated that fhb-deficient mutants had diminished phagocytosis resistance in bactericidal assays. In addition, Fhb plays important roles in complement-mediated immunity by interacting with hFH. These findings indicated that Fhb is a crucial surface protein contributing to the virulence of S. suis, with important functions in evading innate immune defenses by interaction with host complement regulatory factor hFH.
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Sanchez CJ, Hinojosa CA, Shivshankar P, Hyams C, Camberlein E, Brown JS, Orihuela CJ. Changes in capsular serotype alter the surface exposure of pneumococcal adhesins and impact virulence. PLoS One 2011; 6:e26587. [PMID: 22028914 PMCID: PMC3197518 DOI: 10.1371/journal.pone.0026587] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 09/29/2011] [Indexed: 12/26/2022] Open
Abstract
We examined the contribution of serotype on Streptococcus pneumoniae adhesion and virulence during respiratory tract infection using a panel of isogenic TIGR4 (serotype 4) mutants expressing the capsule types 6A (+6A), 7F (+7F) and 23F (+23F) as well as a deleted and restored serotype 4 (+4) control strain. Immunoblots, bacterial capture assays with immobilized antibody, and measurement of mean fluorescent intensity by flow cytometry following incubation of bacteria with antibody, all determined that the surface accessibility, but not total protein levels, of the virulence determinants Pneumococcal surface protein A (PspA), Choline binding protein A (CbpA), and Pneumococcal serine-rich repeat protein (PsrP) changed with serotype. In vitro, bacterial adhesion to Detroit 562 pharyngeal or A549 lung epithelial cells was modestly but significantly altered for +6A, +7F and +23F. In a mouse model of nasopharyngeal colonization, the number of +6A, +7F, and +23F pneumococci in the nasopharynx was reduced 10 to 100-fold versus +4; notably, only mice challenged with +4 developed bacteremia. Intratracheal challenge of mice confirmed that capsule switch strains were highly attenuated for virulence. Compared to +4, the +6A, +7F, and +23F strains were rapidly cleared from the lungs and were not detected in the blood. In mice challenged intraperitoneally, a marked reduction in bacterial blood titers was observed for those challenged with +6A and +7F versus +4 and +23F was undetectable. These findings show that serotype impacts the accessibility of surface adhesins and, in particular, affects virulence within the respiratory tract. They highlight the complex interplay between capsule and protein virulence determinants.
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Affiliation(s)
- Carlos J. Sanchez
- Department of Microbiology and Immunology, The University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Cecilia A. Hinojosa
- Department of Microbiology and Immunology, The University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Pooja Shivshankar
- Department of Microbiology and Immunology, The University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Catherine Hyams
- Department of Medicine, Centre for Respiratory Research, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Emilie Camberlein
- Department of Medicine, Centre for Respiratory Research, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Jeremy S. Brown
- Department of Medicine, Centre for Respiratory Research, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Carlos J. Orihuela
- Department of Microbiology and Immunology, The University of Texas Health Science Center, San Antonio, Texas, United States of America
- * E-mail:
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Hyams C, Opel S, Hanage W, Yuste J, Bax K, Henriques-Normark B, Spratt BG, Brown JS. Effects of Streptococcus pneumoniae strain background on complement resistance. PLoS One 2011; 6:e24581. [PMID: 22022358 PMCID: PMC3192701 DOI: 10.1371/journal.pone.0024581] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 08/15/2011] [Indexed: 01/04/2023] Open
Abstract
Background Immunity to infections caused by Streptococcus pneumoniae is dependent on complement. There are wide variations in sensitivity to complement between S. pneumoniae strains that could affect their ability to cause invasive infections. Although capsular serotype is one important factor causing differences in complement resistance between strains, there is also considerable other genetic variation between S. pneumoniae strains that may affect complement-mediated immunity. We have therefore investigated whether genetically distinct S. pneumoniae strains with the same capsular serotype vary in their sensitivity to complement mediated immunity. Methodology and Principal Findings C3b/iC3b deposition and neutrophil association were measured using flow cytometry assays for S. pneumoniae strains with different genetic backgrounds for each of eight capsular serotypes. For some capsular serotypes there was marked variation in C3b/iC3b deposition between different strains that was independent of capsule thickness and correlated closely to susceptibility to neutrophil association. C3b/iC3b deposition results also correlated weakly with the degree of IgG binding to each strain. However, the binding of C1q (the first component of the classical pathway) correlated more closely with C3b/iC3b deposition, and large differences remained in complement sensitivity between strains with the same capsular serotype in sera in which IgG had been cleaved with IdeS. Conclusions These data demonstrate that bacterial factors independent of the capsule and recognition by IgG have strong effects on the susceptibility of S. pneumoniae to complement, and could therefore potentially account for some of the differences in virulence between strains.
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Affiliation(s)
- Catherine Hyams
- Centre for Respiratory Research, Department of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Sophia Opel
- Centre for Respiratory Research, Department of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - William Hanage
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Jose Yuste
- Spanish Pneumococcal Reference Laboratory, Centro Nacional de Microbiologia, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Katie Bax
- Department of Anatomy, University College London, London, United Kingdom
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet and the Swedish Institute for Infectious Disease Control, Stockholm, Sweden
| | - Brian G. Spratt
- Department of Infectious Disease Epidemiology, St. Mary's Hospital Campus, Imperial College London, London, United Kingdom
| | - Jeremy S. Brown
- Centre for Respiratory Research, Department of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
- * E-mail:
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Wilkosz S, Edwards LA, Bielsa S, Hyams C, Taylor A, Davies RJO, Laurent GJ, Chambers RC, Brown JS, Lee YCG. Characterization of a new mouse model of empyema and the mechanisms of pleural invasion by Streptococcus pneumoniae. Am J Respir Cell Mol Biol 2011; 46:180-7. [PMID: 21885676 DOI: 10.1165/rcmb.2011-0182oc] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Although empyema affects more than 65,000 people each year in the United States and in the United Kingdom, there are limited data on the pathogenesis of pleural infection. We investigated the pathogenesis of empyema using animal and cell culture models of Streptococcus pneumoniae infection. The pathological processes during the development of empyema associated with murine pneumonia due to S. pneumoniae (strain D39) were investigated. Lungs were examined using histology, and pleural fluid and blood bacterial colony-forming units, cytokine levels, and cellular infiltrate were determined over time. Bacterial migration across mesothelial monolayers was investigated using cell culture techniques, flow cytometry, and confocal microscopy. After intranasal inoculation with 10(7) S. pneumoniae D39 strain, mice developed pneumonia associated with rapid bacterial invasion of the pleural space; raised intrapleural IL-8, VEGF, MCP-1, and TNF-α levels; and caused significant intrapleural neutrophilia followed by the development of fibrinous pleural adhesions. Bacterial clearance from the pleural space was poor, and in vitro assays demonstrated that S. pneumoniae crossed mesothelial layers by translocation through cells rather than by a paracellular route. This study describes key events during the development of S. pneumoniae empyema using a novel murine model of pneumonia-associated empyema that closely mimics human disease. The model allows for future assessment of molecular mechanisms involved in the development of empyema and evaluation of potential new therapies. The data suggest that transmigration of bacteria through mesothelial cells could be important in empyema development. Furthermore, upon entry the pleural cavity offers a protected compartment for the bacteria.
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Affiliation(s)
- Sylwia Wilkosz
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, 5 University Street, London, UK.
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Nasopharyngeal colonization and invasive disease are enhanced by the cell wall hydrolases LytB and LytC of Streptococcus pneumoniae. PLoS One 2011; 6:e23626. [PMID: 21886805 PMCID: PMC3160309 DOI: 10.1371/journal.pone.0023626] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 07/21/2011] [Indexed: 01/07/2023] Open
Abstract
Background Streptococcus pneumoniae is a common colonizer of the human nasopharynx and one of the major pathogens causing invasive disease worldwide. Dissection of the molecular pathways responsible for colonization, invasion, and evasion of the immune system will provide new targets for antimicrobial or vaccine therapies for this common pathogen. Methodology/Principal Findings We have constructed mutants lacking the pneumococcal cell wall hydrolases (CWHs) LytB and LytC to investigate the role of these proteins in different phases of the pneumococcal pathogenesis. Our results show that LytB and LytC are involved in the attachment of S. pneumoniae to human nasopharyngeal cells both in vitro and in vivo. The interaction of both proteins with phagocytic cells demonstrated that LytB and LytC act in concert avoiding pneumococcal phagocytosis mediated by neutrophils and alveolar macrophages. Furthermore, C3b deposition was increased on the lytC mutant confirming that LytC is involved in complement evasion. As a result, the lytC mutant showed a reduced ability to successfully cause pneumococcal pneumonia and sepsis. Bacterial mutants lacking both LytB and LytC showed a dramatically impaired attachment to nasopharyngeal cells as well as a marked degree of attenuation in a mouse model of colonization. In addition, C3b deposition and phagocytosis was more efficient for the double lytB lytC mutant and its virulence was greatly impaired in both systemic and pulmonary models of infection. Conclusions/Significance This study confirms that the CWHs LytB and LytC of S. pneumoniae are essential virulence factors involved in the colonization of the nasopharynx and in the progress of invasive disease by avoiding host immunity.
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Sanders ME, Norcross EW, Moore QC, Onwubiko C, King LB, Fratkin J, Marquart ME. A comparison of pneumolysin activity and concentration in vitro and in vivo in a rabbit endophthalmitis model. Clin Ophthalmol 2011; 2:793-800. [PMID: 19668433 PMCID: PMC2699808 DOI: 10.2147/opth.s3941] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to determine whether the in vitro activity and concentration of Streptococcus pneumoniae pneumolysin correlated to the pathogenesis of S. pneumoniae endophthalmitis. Five S. pneumoniae clinical endophthalmitis strains were grown in media to similar optical densities (OD), and extracellular milieu was tested for pneumolysin activity by hemolysis of rabbit red blood cells. Pneumolysin concentration was determined using a sandwich ELISA. Rabbit vitreous was injected with 102 colony-forming units (CFU) of 1 of 2 different strains with low hemolytic activity (n = 10 and 12 for strains 4 and 5, respectively) or 1 of 3 different strains with high hemolytic activity (n = 12 per strain). Pathogenesis of endophthalmitis infection was graded by slit lamp examination (SLE) at 24 hours post-infection. Bacteria were recovered from infected vitreous and quantitated. The SLE scores of eyes infected with strains having high hemolytic activity were significantly higher than the scores of those infected with strains having low hemolytic activity (P < 0.05). Pneumolysin concentration in vitro, however, did not correlate with hemolysis or severity of endophthalmitis. Bacterial concentrations from the vitreous infected with 4 of the strains were not significantly different (P > 0.05). These data suggest that pneumolysin hemolytic activity in vitro directly correlates to the pathogenesis of S. pneumoniae endophthalmitis. The protein concentration of pneumolysin, however, is not a reliable indicator of pneumolysin activity.
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The capsular serotype of Streptococcus pneumoniae is more important than the genetic background for resistance to complement. Infect Immun 2010; 78:5262-70. [PMID: 20855513 DOI: 10.1128/iai.00740-10] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The polysaccharide capsule of Streptococcus pneumoniae inhibits phagocytic killing by innate immune mechanisms. Certain serotypes are associated with invasive disease while others with a nasopharyngeal carriage. The invasiveness of serotypes may partly be explained by ability to resist deposition of complement (C3) on the bacterial surface and consequent opsonophagocytic killing. In our previous studies, we observed that clinical isolates of serotypes 1 and 5, which are rarely detected in asymptomatic carriage, were resistant to complement deposition and opsonophagocytosis, whereas serotypes 6B and 23F, both common in carriage, were more sensitive to deposition of C3 and opsonophagocytic killing. However, presence of significant variation in C3 deposition between isolates of the same serotype indicated that factors other than the capsule also affect complement resistance. To distinguish the relative effect of the capsular serotype and other virulence factors on C3 deposition, we compared capsule-switched mutants prepared in genetic backgrounds of pneumococcal strains TIGR4, 603, and 618. Clinical isolates which had the same multilocus sequence type but expressed different serotypes were also compared. We found that the serotype had a significant impact on complement resistance and that the more resistant the strain was to complement, the higher was the concentration of polysaccharide-specific antibodies required for opsonophagocytic killing. Comparison of strains expressing the same capsular polysaccharides in the different genetic backgrounds and various capsular mutants of the same strain suggests that while the genotype affects complement resistance, the serotype is the most important determinant. Differences between serotypes were more significant than the differences between strains.
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