1
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Payen S, Giroux MC, Gisch N, Schombel U, Fittipaldi N, Segura M, Gottschalk M. Lipoteichoic acids influence cell shape and bacterial division of Streptococcus suis serotype 2, but play a limited role in the pathogenesis of the infection. Vet Res 2024; 55:34. [PMID: 38504299 PMCID: PMC10953176 DOI: 10.1186/s13567-024-01287-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 03/01/2024] [Indexed: 03/21/2024] Open
Abstract
Streptococcus suis serotype 2 is a major swine pathogen and a zoonotic agent, causing meningitis in both swine and humans, responsible for substantial economic losses to the swine industry worldwide. The pathogenesis of infection and the role of bacterial cell wall components in virulence have not been fully elucidated. Lipoproteins, peptidoglycan, as well as lipoteichoic acids (LTA) have all been proposed to contribute to virulence. In the present study, the role of the LTA in the pathogenesis of the infection was evaluated through the characterisation of a mutant of the S. suis serotype 2 strain P1/7 lacking the LtaS enzyme, which mediates the polymerization of the LTA poly-glycerolphosphate chain. The ltaS mutant was confirmed to completely lack LTA and displayed significant morphological defects. Although the bacterial growth of this mutant was not affected, further results showed that LTA is involved in maintaining S. suis bacterial fitness. However, its role in the pathogenesis of the infection appears limited. Indeed, LTA presence reduces self-agglutination, biofilm formation and even dendritic cell activation, which are important aspects of the pathogenesis of the infection caused by S. suis. In addition, it does not seem to play a critical role in virulence using a systemic mouse model of infection.
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Affiliation(s)
- Servane Payen
- Research Group On Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, J2S 2M2, Canada
| | - Marie-Christine Giroux
- Research Group On Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, J2S 2M2, Canada
| | - Nicolas Gisch
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Ursula Schombel
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Nahuel Fittipaldi
- Research Group On Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, J2S 2M2, Canada
| | - Mariela Segura
- Research Group On Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, J2S 2M2, Canada
| | - Marcelo Gottschalk
- Research Group On Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, J2S 2M2, Canada.
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2
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Nogueira WG, Jaiswal AK, Tiwari S, Ramos RTJ, Ghosh P, Barh D, Azevedo V, Soares SC. Computational identification of putative common genomic drug and vaccine targets in Mycoplasma genitalium. Genomics 2021; 113:2730-2743. [PMID: 34118385 DOI: 10.1016/j.ygeno.2021.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/17/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022]
Abstract
Mycoplasma genitalium is an obligate intracellular bacterium that is responsible for several sexually transmitted infections, including non-gonococcal urethritis in men and several inflammatory reproductive tract syndromes in women. Here, we applied subtractive genomics and reverse vaccinology approaches for in silico prediction of potential vaccine and drug targets against five strains of M. genitalium. We identified 403 genes shared by all five strains, from which 104 non-host homologous proteins were selected, comprising of 44 exposed/secreted/membrane proteins and 60 cytoplasmic proteins. Based on the essentiality, functionality, and structure-based binding affinity, we finally predicted 19 (14 novel) putative vaccine and 7 (2 novel) candidate drug targets. The docking analysis showed six molecules from the ZINC database as promising drug candidates against the identified targets. Altogether, both vaccine candidates and drug targets identified here may contribute to the future development of therapeutic strategies to control the spread of M. genitalium worldwide.
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Affiliation(s)
- Wylerson G Nogueira
- Laboratório de Genética Celular e Molecular, Departamento de Genetica, Ecologia e Evolucao, Instituto de Ciências Biológicas,Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Arun Kumar Jaiswal
- Laboratório de Genética Celular e Molecular, Departamento de Genetica, Ecologia e Evolucao, Instituto de Ciências Biológicas,Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.; Department of Immunology, Microbiology and Parasitology, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - Sandeep Tiwari
- Laboratório de Genética Celular e Molecular, Departamento de Genetica, Ecologia e Evolucao, Instituto de Ciências Biológicas,Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil..
| | - Rommel T J Ramos
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Preetam Ghosh
- Department of Computer Science, Virginia Commonwealth University, Richmond VA-23284, USA
| | - Debmalya Barh
- Centre for Genomics and Applied Gene Technology, Institute of Integrative Omics and Applied Biotechnology (IIOAB), Nonakuri, Purba Medinipur, West Bengal, India
| | - Vasco Azevedo
- Laboratório de Genética Celular e Molecular, Departamento de Genetica, Ecologia e Evolucao, Instituto de Ciências Biológicas,Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Siomar C Soares
- Department of Immunology, Microbiology and Parasitology, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais, Brazil.
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3
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Abstract
Streptococcus mutans is a Gram-positive bacterium that thrives under acidic conditions and is a primary cause of tooth decay (dental caries). To better understand the metabolism of S. mutans on a systematic level, we manually constructed a genome-scale metabolic model of the S. mutans type strain UA159. The model, called iSMU, contains 675 reactions involving 429 metabolites and the products of 493 genes. We validated iSMU by comparing simulations with growth experiments in defined medium. The model simulations matched experimental results for 17 of 18 carbon source utilization assays and 47 of 49 nutrient depletion assays. We also simulated the effects of single gene deletions. The model's predictions agreed with 78.1% and 84.4% of the gene essentiality predictions from two experimental data sets. Our manually curated model is more accurate than S. mutans models generated from automated reconstruction pipelines and more complete than other manually curated models. We used iSMU to generate hypotheses about the S. mutans metabolic network. Subsequent genetic experiments confirmed that (i) S. mutans catabolizes sorbitol via a sorbitol-6-phosphate 2-dehydrogenase (SMU_308) and (ii) the Leloir pathway is required for growth on complex carbohydrates such as raffinose. We believe the iSMU model is an important resource for understanding the metabolism of S. mutans and guiding future experiments.IMPORTANCE Tooth decay is the most prevalent chronic disease in the United States. Decay is caused by the bacterium Streptococcus mutans, an oral pathogen that ferments sugars into tooth-destroying lactic acid. We constructed a complete metabolic model of S. mutans to systematically investigate how the bacterium grows. The model provides a valuable resource for understanding and targeting S. mutans' ability to outcompete other species in the oral microbiome.
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4
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Jang AY, Ahn KB, Zhi Y, Ji HJ, Zhang J, Han SH, Guo H, Lim S, Song JY, Lim JH, Seo HS. Serotype-Independent Protection Against Invasive Pneumococcal Infections Conferred by Live Vaccine With lgt Deletion. Front Immunol 2019; 10:1212. [PMID: 31191555 PMCID: PMC6549034 DOI: 10.3389/fimmu.2019.01212] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/13/2019] [Indexed: 01/10/2023] Open
Abstract
Streptococcus pneumoniae is the most common respiratory bacterial pathogen among cases of community-acquired infection in young children, older adults, and individuals with underlying medical conditions. Although capsular polysaccharide-based pneumococcal vaccines have contributed to significant decrease in invasive pneumococcal infections, these vaccines have some limitations, including limited serotype coverage, lack of effective mucosal antibody responses, and high costs. In this study, we investigated the safety and immunogenicity of a live, whole-cell pneumococcal vaccine constructed by deleting the gene for prolipoprotein diacylglyceryl transferase (lgt) from the encapsulated pneumococcal strain TIGR4 (TIGR4Δlgt) for protection against heterologous pneumococcal strains. Pneumococcal strain TIGR4 was successfully attenuated by deletion of lgt, resulting in the loss of inflammatory activity and virulence. TIGR4Δlgt colonized the nasopharynx long enough to induce strong mucosal IgA and IgG2b-dominant systemic antibody responses that were cross-reactive to heterologous pneumococcal serotypes. Finally, intranasal immunization with TIGR4Δlgt provided serotype-independent protection against pneumococcal challenge in mice. Taken together, our results suggest that TIGR4Δlgt is an avirulent and attractive broad-spectrum pneumococcal vaccine candidate. More broadly, we assert that modulation of such "master" metabolic genes represents an emerging strategy for developing more effective vaccines against numerous infectious agents.
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Affiliation(s)
- A-Yeung Jang
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea.,Department of Internal Medicine, Korea University College of Medicine, Seoul, South Korea
| | - Ki Bum Ahn
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea
| | - Yong Zhi
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea.,Department of Radiation Science and Technology, University of Science and Technology, Daejeon, South Korea
| | - Hyun-Jung Ji
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea.,DRI and BK21 Plus Program, Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Jing Zhang
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea
| | - Seung Hyun Han
- DRI and BK21 Plus Program, Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Huichen Guo
- State Key Laboratory of Veterinary Etiological Biology, National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Sangyong Lim
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea.,Department of Radiation Science and Technology, University of Science and Technology, Daejeon, South Korea
| | - Joon Yong Song
- Department of Internal Medicine, Korea University College of Medicine, Seoul, South Korea
| | - Jae Hyang Lim
- Department of Microbiology, Ewha Womans University College of Medicine, Seoul, South Korea
| | - Ho Seong Seo
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, South Korea.,Department of Radiation Science and Technology, University of Science and Technology, Daejeon, South Korea
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5
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Arimoto T, Yambe R, Morisaki H, Umezawa H, Kataoka H, Matsui S, Kuwata H. Influence of excess branched-chain amino acid uptake by Streptococcus mutans in human host cells. FEMS Microbiol Lett 2018; 365:4733272. [PMID: 29240953 DOI: 10.1093/femsle/fnx273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 12/11/2017] [Indexed: 11/12/2022] Open
Abstract
Oral streptococci, including cariogenic bacterium Streptococcus mutans, comprise a large percentage of human supragingival plaque, which contacts both tooth surfaces and gingiva. Eukaryotic cells are able to take up macromolecules and particles, including bacteria, by endocytosis. Increasing evidence indicates endocytosis may be used as an entry process by bacteria. We hypothesized that some endocytosed bacteria might survive and obtain nutrients, such as amino acids, until they are killed. To verify this hypothesis, we focused on bacterial utilization of branched-chain amino acids (BCAAs; isoleucine, leucine and valine) in host cells. A branched-chain aminotransferase, IlvE (EC 2.6.1.42), has been suggested to play an important role in internal synthesis of BCAAs in S. mutans UA159. Therefore, we constructed an ilvE-deficient S. mutans 109c strain and confirmed that it had similar growth behavior as reported previously. 14C radioactive leucine uptake assays showed that ilvE-deficient S. mutans took up more leucine both inside and outside of host cells. We further clarified that a relative decrease of BCAAs in host cells caused enhanced endocytic and autophagic activity. In conclusion, S. mutans is endocytosed by host cells and may survive and obtain nutrients, such as BCAAs, inside the cells, which might affect cellular functions of host cells.
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Affiliation(s)
- Takafumi Arimoto
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Rei Yambe
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Hirobumi Morisaki
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Haruka Umezawa
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Hideo Kataoka
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Shohei Matsui
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan.,Division of Community-Based Comprehensive Dentistry, Department of Special Needs Dentistry, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Hirotaka Kuwata
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
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6
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Kunii M, Arimoto T, Hasegawa T, Kuwata H, Igarashi T. Role of protease maturation lipoprotein in osmoadaptation of Streptococcus mutans. FEMS Microbiol Lett 2014; 356:45-52. [PMID: 24863612 DOI: 10.1111/1574-6968.12477] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/16/2014] [Accepted: 05/22/2014] [Indexed: 12/18/2022] Open
Abstract
Osmoadaptation may be an important trait for the pathogenicity of Streptococcus mutans. However, how this organism adapts to changes in osmolality in the oral cavity remains unclear. In this study, we showed that S. mutans utilizes K(+) for osmoadaptation, in which protease maturation lipoprotein (PrtM) plays an important role. Although growth of the wild-type strain was impaired in a hyperosmotic medium [brain heart infusion (BHI) containing 0.3 M NaCl] compared with that in an unmodified BHI, the prtM mutant grew much more poorly in 0.3 M NaCl BHI. Comparison of growth behavior in the hyperosmotic medium supplemented with different osmoprotectants revealed that only the addition of K(+) allowed the bacteria to overcome the impairment of growth caused by the high osmolality. These results suggest that K(+) is an important compatible solute for S. mutans. Moreover, K(+) -associated recovery of growth was not observed for the prtM mutant, indicating that PrtM plays a critical role in the utilization of K(+) . Quantitative reverse-transcriptase polymerase chain reaction analysis showed that prtM was induced by osmotic stress, implying that prtM is an osmoresponsive gene. These findings suggest that K(+) is an important compatible solute for S. mutans, and that the osmoresponsive lipoprotein PrtM is involved in K(+) utilization, contributing to osmoadaptation of S. mutans.
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Affiliation(s)
- Maiko Kunii
- Department of Oral Microbiology and Immunology, Showa University School of Dentistry, Tokyo, Japan; Division of Comprehensive Dentistry, Department of Conservative Dentistry, Showa University School of Dentistry, Tokyo, Japan
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7
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Segawa T, Saeki A, Hasebe A, Arimoto T, Kataoka H, Yokoyama A, Kawanami M, Shibata KI. Differences in recognition of wild-type and lipoprotein-deficient strains of oralStreptococci in vitroandin vivo. Pathog Dis 2013; 68:65-77. [DOI: 10.1111/2049-632x.12049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/23/2013] [Accepted: 05/24/2013] [Indexed: 01/11/2023] Open
Affiliation(s)
| | - Ayumi Saeki
- Division of Oral Molecular Microbiology; Department of Oral Pathobiological Science; Hokkaido University Graduate School of Dental Medicine; Kita-ku; Sapporo; Japan
| | - Akira Hasebe
- Division of Oral Molecular Microbiology; Department of Oral Pathobiological Science; Hokkaido University Graduate School of Dental Medicine; Kita-ku; Sapporo; Japan
| | - Takafumi Arimoto
- Department of Oral Microbiology; Showa University School of Dentistry; Shinagawa-ku; Tokyo; Japan
| | - Hideo Kataoka
- Department of Oral Microbiology; Showa University School of Dentistry; Shinagawa-ku; Tokyo; Japan
| | - Atsuro Yokoyama
- Division of Oral Functional Science; Department of Oral Functional Prosthodontics; Hokkaido University Graduate School of Dental Medicine; Kita-ku; Sapporo; Japan
| | - Masamitsu Kawanami
- Division of Oral Health Science; Department of Periodontology and Endodontology; Hokkaido University Graduate School of Dental Medicine; Kita-ku; Sapporo; Japan
| | - Ken-ichiro Shibata
- Division of Oral Molecular Microbiology; Department of Oral Pathobiological Science; Hokkaido University Graduate School of Dental Medicine; Kita-ku; Sapporo; Japan
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8
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Cho K, Arimoto T, Igarashi T, Yamamoto M. Involvement of lipoprotein PpiA ofStreptococcus gordoniiin evasion of phagocytosis by macrophages. Mol Oral Microbiol 2013; 28:379-91. [DOI: 10.1111/omi.12031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2013] [Indexed: 11/29/2022]
Affiliation(s)
| | - T. Arimoto
- Department of Oral Microbiology and Immunology; Showa University School of Dentistry; Tokyo; Japan
| | - T. Igarashi
- Department of Oral Microbiology and Immunology; Showa University School of Dentistry; Tokyo; Japan
| | - M. Yamamoto
- Department of Periodontology; Showa University School of Dentistry; Tokyo; Japan
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Saeki A, Segawa T, Abe T, Sugiyama M, Arimoto T, Hara H, Hasebe A, Ohtani M, Tanizume N, Ohuchi M, Kataoka H, Kawanami M, Yokoyama A, Shibata K. Toll-like receptor 2-mediated modulation of growth and functions of regulatory T cells by oral streptococci. Mol Oral Microbiol 2013; 28:267-80. [PMID: 23413817 DOI: 10.1111/omi.12023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/01/2013] [Indexed: 11/30/2022]
Abstract
This study was designed to determine whether oral streptococci modulate the growth and functions of regulatory T cells. Heat-killed cells of wild-type strains of Streptococcus gordonii and Streptococcus mutans induced the Toll-like receptor 2 (TLR2) -mediated nuclear factor-κB (NF-κB) activation, but their lipoprotein-deficient strains did not. Stimulation with these streptococci resulted in a significant increase in the frequency of CD4(+) CD25(+) Foxp3(+) regulatory T cells in splenocytes derived from both TLR2(+/+) and TLR2(-/-) mice, but the level of increase in TLR2(+/+) splenocytes was stronger than that in TLR2(-/-) splenocytes. Both strains of S. gordonii enhanced the proliferation of CD4(+) CD25(+) Foxp3(+) regulatory T cells isolated from TLR2(+/+) mice at the same level as those from TLR2(-/-) mice in an interleukin-2-independent manner. However, wild-type and lipoprotein-deficient strains of both streptococci did not enhance the suppressive activity of the isolated regulatory T cells in vitro, but rather inhibited it. TLR ligands also inhibited the suppressive activity of the regulatory T cells. Inhibition of the suppressive activity was recovered by the addition of anti-IL-6 antibody. Pretreatment of antigen-presenting cells with the NF-κB inhibitor BAY11-7082 enhanced the suppressive activity of the regulatory T cells. These results suggested that interleukin-6 produced by antigen-presenting cells inhibits the suppressive activity of the regulatory T cells. Wild-type strain, but not lipoprotein-deficient strain, of S. gordonii reduced the frequency of CD4(+) CD25(+) Foxp3(+) regulatory T cells in the acute infection model, whereas both strains of S. gordonii increased it in the chronic infection model mice. Hence, this study suggests that oral streptococci are capable of modulating the growth and functions of regulatory T cells in vitro and in vivo.
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Affiliation(s)
- A Saeki
- Division of Oral Molecular Microbiology, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan
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10
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Chimalapati S, Cohen JM, Camberlein E, MacDonald N, Durmort C, Vernet T, Hermans PWM, Mitchell T, Brown JS. Effects of deletion of the Streptococcus pneumoniae lipoprotein diacylglyceryl transferase gene lgt on ABC transporter function and on growth in vivo. PLoS One 2012; 7:e41393. [PMID: 22911788 PMCID: PMC3404074 DOI: 10.1371/journal.pone.0041393] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 06/21/2012] [Indexed: 12/14/2022] Open
Abstract
Lipoproteins are an important class of surface associated proteins that have diverse roles and frequently are involved in the virulence of bacterial pathogens. As prolipoproteins are attached to the cell membrane by a single enzyme, prolipoprotein diacylglyceryl transferase (Lgt), deletion of the corresponding gene potentially allows the characterisation of the overall importance of lipoproteins for specific bacterial functions. We have used a Δlgt mutant strain of Streptococcus pneumoniae to investigate the effects of loss of lipoprotein attachment on cation acquisition, growth in media containing specific carbon sources, and virulence in different infection models. Immunoblots of triton X-114 extracts, flow cytometry and immuno-fluorescence microscopy confirmed the Δlgt mutant had markedly reduced lipoprotein expression on the cell surface. The Δlgt mutant had reduced growth in cation depleted medium, increased sensitivity to oxidative stress, reduced zinc uptake, and reduced intracellular levels of several cations. Doubling time of the Δlgt mutant was also increased slightly when grown in medium with glucose, raffinose and maltotriose as sole carbon sources. These multiple defects in cation and sugar ABC transporter function for the Δlgt mutant were associated with only slightly delayed growth in complete medium. However the Δlgt mutant had significantly reduced growth in blood or bronchoalveolar lavage fluid and a marked impairment in virulence in mouse models of nasopharyngeal colonisation, sepsis and pneumonia. These data suggest that for S. pneumoniae loss of surface localisation of lipoproteins has widespread effects on ABC transporter functions that collectively prevent the Δlgt mutant from establishing invasive infection.
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Affiliation(s)
- Suneeta Chimalapati
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Jonathan M. Cohen
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
- Infectious Diseases & Microbiology Unit, UCL Institute of Child Health, London, United Kingdom
| | - Emilie Camberlein
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Nathanael MacDonald
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Claire Durmort
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- CNRS, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- Université Joseph Fourier – Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
| | - Thierry Vernet
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- CNRS, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- Université Joseph Fourier – Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
| | - Peter W. M. Hermans
- Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Timothy Mitchell
- Division of Infection and Immunity, IBLS, University of Glasgow, Glasgow, United Kingdom
| | - Jeremy S. Brown
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
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11
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Surface lipoprotein PpiA of Streptococcus mutans suppresses scavenger receptor MARCO-dependent phagocytosis by macrophages. Infect Immun 2011; 79:4933-40. [PMID: 21986627 DOI: 10.1128/iai.05693-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Streptococcus mutans is associated with the initiation and progression of human dental caries and is occasionally isolated from the blood of patients with bacteremia and infective endocarditis. For the pathogen to survive in the infected host, surface lipoproteins of S. mutans are likely to play important roles in interactions with the innate immune system. To clarify the role that a putative lipoprotein, peptidyl-prolyl cis/trans-isomerase (PpiA), of S. mutans plays in the macrophage response, we investigated the response of THP-1-derived macrophages to S. mutans challenge. The deletion of the gene encoding Lgt eliminated PpiA on the cell surface of S. mutans, which implies that PpiA is a lipoprotein that is lipid anchored in the cell membrane by Lgt. Human and murine peritoneal macrophages both showed higher phagocytic activities for the ppiA and lgt mutants than the wild type, which indicates that the presence of PpiA reduces S. mutans phagocytosis. In addition, infection with S. mutans markedly induced mRNAs of macrophage receptor with collagenous structure (MARCO) and scavenger receptor A (SR-A) in human macrophages. In particular, transcriptional and translational levels of MARCO in human macrophages infected with the ppiA mutant were higher than those in macrophages infected with the wild type. Phagocytosis of S. mutans by human macrophages markedly decreased after treatment with anti-MARCO IgG. These results demonstrate that the S. mutans lipoprotein PpiA contributes to suppression of MARCO-mediated phagocytosis of this bacterium by macrophages.
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