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Carvalho TP, Toledo FAO, Bautista DFA, Silva MF, Oliveira JBS, Lima PA, Costa FB, Ribeiro NQ, Lee JY, Birbrair A, Paixão TA, Tsolis RM, Santos RL. Pericytes modulate endothelial inflammatory response during bacterial infection. mBio 2024; 15:e0325223. [PMID: 38289074 PMCID: PMC10936204 DOI: 10.1128/mbio.03252-23] [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: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 03/14/2024] Open
Abstract
Pericytes are located around blood vessels, in close contact with endothelial cells. We discovered that pericytes dampen pro-inflammatory endothelial cell responses. Endothelial cells co-cultured with pericytes had markedly reduced expression of adhesion molecules (PECAM-1 and ICAM-1) and proinflammatory cytokines (CCL-2 and IL-6) in response to bacterial stimuli (Brucella ovis, Listeria monocytogenes, or Escherichia coli lipopolysaccharide). Pericyte-depleted mice intraperitoneally inoculated with either B. ovis, a stealthy pathogen that does not trigger detectable inflammation, or Listeria monocytogenes, developed peritonitis. Further, during Citrobacter rodentium infection, pericyte-depleted mice developed severe intestinal inflammation, which was not evident in control mice. The anti-inflammatory effect of pericytes required connexin 43, as either chemical inhibition or silencing of connexin 43 abrogated pericyte-mediated suppression of endothelial inflammatory responses. Our results define a mechanism by which pericytes modulate inflammation during infection, which shifts our understanding of pericyte biology: from a structural cell to a pro-active player in modulating inflammation. IMPORTANCE A previously unknown mechanism by which pericytes modulate inflammation was discovered. The absence of pericytes or blocking interaction between pericytes and endothelium through connexin 43 results in stronger inflammation, which shifts our understanding of pericyte biology, from a structural cell to a player in controlling inflammation.
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Affiliation(s)
- Thaynara P. Carvalho
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
| | - Frank A. O. Toledo
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Diego F. A. Bautista
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Monique F. Silva
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Jefferson B. S. Oliveira
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Pâmela A. Lima
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Fabíola B. Costa
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Noelly Q. Ribeiro
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Jee-Yon Lee
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
| | - Alexander Birbrair
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Department of Dermatology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Tatiane A. Paixão
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Reneé M. Tsolis
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
| | - Renato L. Santos
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
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Razei A, Javanbakht M, Hajizade A, Heiat M, Zhao S, Aghamollaei H, Saadati M, Khafaei M, Asadi M, Cegolon L, Keihan AH. Nano and microparticle drug delivery systems for the treatment of Brucella infections. Biomed Pharmacother 2023; 169:115875. [PMID: 37979375 DOI: 10.1016/j.biopha.2023.115875] [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: 04/05/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/20/2023] Open
Abstract
Nano-based drug delivery systems are increasingly used for diagnosis, prevention and treatment of several diseases, thanks to several beneficial properties, including the ability to target specific cells or organs, allowing to reduce treatment costs and side effects frequently associated with chemotherapeutic medications, thereby improving treatment compliance of patients. In the field of communicable diseases, especially those caused by intracellular bacteria, the delivery of antibiotics targeting specific cells is of critical importance to maximize their treatment efficacy. Brucella melitensis, an intracellular obligate bacterium surviving and replicating inside macrophages is hard to be eradicated, mainly because of the low ability of antibiotics to enter these phagocityc cells . Although different antibiotics regimens including gentamicin, doxycycline and rifampicin are in fact used against the Brucellosis, no efficient treatment has been attained yet, due to the intracellular life of the respective pathogen. Nano-medicines responding to environmental stimuli allow to maximize drug delivery targeting macropages, thereby boosting treatment efficacy. Several drug delivery nano-technologies, including solid lipid nanoparticles, liposomes, chitosan, niosomes, and their combinations with chitosan sodium alginate can be employed in combination of antibiotics to successfully eradicate Brucellosis infection from patients.
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Affiliation(s)
- Ali Razei
- Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Mohammad Javanbakht
- Nephrology and Urology Research Center,Clinical Science Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Abbas Hajizade
- Biology Research Centre, Faculty of Basic Sciences, Imam Hossain University, Tehran, Iran
| | - Mohammad Heiat
- Baqiyatallah Research Center for Gastroenterology and Liver Diseases (BRCGL), Clinical Sciences Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Shi Zhao
- JC School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China
| | - Hossien Aghamollaei
- Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Mojtaba Saadati
- Biology Research Centre, Faculty of Basic Sciences, Imam Hossain University, Tehran, Iran
| | - Mostafa Khafaei
- Human Genetics Research Center, Baqiyatallah Medical Science University, Tehran, Iran
| | - Mosa Asadi
- Nephrology and Urology Research Center,Clinical Science Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Luca Cegolon
- University of Trieste, Department of Medical, Surgical & Health Sciences, Trieste, Italy; University Health Agency Giuliano-Isontina (ASUGI), Public Health Department, Trieste, Italy
| | - Amir Homayoun Keihan
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
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Challagundla N, Phadnis D, Gupta A, Agrawal-Rajput R. Host Lipid Manipulation by Intracellular Bacteria: Moonlighting for Immune Evasion. J Membr Biol 2023; 256:393-411. [PMID: 37938349 DOI: 10.1007/s00232-023-00296-8] [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: 09/11/2023] [Accepted: 10/11/2023] [Indexed: 11/09/2023]
Abstract
Lipids are complex organic molecules that fulfill energy demands and sometimes act as signaling molecules. They are mostly found in membranes, thus playing an important role in membrane trafficking and protecting the cell from external dangers. Based on the composition of the lipids, their fluidity and charge, their interaction with embedded proteins vary greatly. Bacteria can hijack host lipids to satisfy their energy needs or to conceal themselves from host cells. Intracellular bacteria continuously exploit host, from their entry into host cells utilizing host lipid machinery to exiting through the cells. This acquisition of lipids from host cells helps in their disguise mechanism. The current review explores various mechanisms employed by the intracellular bacteria to manipulate and acquire host lipids. It discusses their role in manipulating host membranes and the subsequence impact on the host cells. Modulating these lipids in macrophages not only serve the purpose of the pathogen but also modulates the macrophage energy metabolism and functional state. Additionally, we have explored the intricate pathogenic relationship and the potential prospects of using this knowledge in lipid-based therapeutics to disrupt pathogen dominance.
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Affiliation(s)
- Naveen Challagundla
- Immunology Lab, Indian Institute of Advanced Research, Koba Institutional Area, Gandhinagar, Gujarat, 382426, India
| | - Deepti Phadnis
- Immunology Lab, Indian Institute of Advanced Research, Koba Institutional Area, Gandhinagar, Gujarat, 382426, India
| | - Aakriti Gupta
- Immunology Lab, Indian Institute of Advanced Research, Koba Institutional Area, Gandhinagar, Gujarat, 382426, India
| | - Reena Agrawal-Rajput
- Immunology Lab, Indian Institute of Advanced Research, Koba Institutional Area, Gandhinagar, Gujarat, 382426, India.
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4
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Peruń A, Gębicka M, Biedroń R, Skalska P, Józefowski S. The CD36 and SR-A/CD204 scavenger receptors fine-tune Staphylococcus aureus-stimulated cytokine production in mouse macrophages. Cell Immunol 2022; 372:104483. [DOI: 10.1016/j.cellimm.2022.104483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 12/20/2021] [Accepted: 01/11/2022] [Indexed: 11/03/2022]
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Chatterjee R, Chowdhury AR, Mukherjee D, Chakravortty D. Lipid larceny: channelizing host lipids for establishing successful pathogenesis by bacteria. Virulence 2021; 12:195-216. [PMID: 33356849 PMCID: PMC7808437 DOI: 10.1080/21505594.2020.1869441] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 12/03/2020] [Accepted: 12/17/2020] [Indexed: 12/16/2022] Open
Abstract
Lipids are complex organic compounds made up of carbon, oxygen, and hydrogen. These play a diverse and intricate role in cellular processes like membrane trafficking, protein sorting, signal transduction, and bacterial infections. Both Gram-positive bacteria (Staphylococcus sp., Listeria monocytogenes, etc.) and Gram-negative bacteria (Chlamydia sp., Salmonella sp., E. coli, etc.) can hijack the various host-lipids and utilize them structurally as well as functionally to mount a successful infection. The pathogens can deploy with various arsenals to exploit host membrane lipids and lipid-associated receptors as an attachment for toxins' landing or facilitate their entry into the host cellular niche. Bacterial species like Mycobacterium sp. can also modulate the host lipid metabolism to fetch its carbon source from the host. The sequential conversion of host membrane lipids into arachidonic acid and prostaglandin E2 due to increased activity of cPLA-2 and COX-2 upon bacterial infection creates immunosuppressive conditions and facilitates the intracellular growth and proliferation of bacteria. However, lipids' more debatable role is that they can also be a blessing in disguise. Certain host-lipids, especially sphingolipids, have been shown to play a crucial antibacterial role and help the host in combating the infections. This review shed light on the detailed role of host lipids in bacterial infections and the current understanding of the lipid in therapeutics. We have also discussed potential prospects and the need of the hour to help us cope in this race against deadly pathogens and their rapidly evolving stealthy virulence strategies.
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Affiliation(s)
- Ritika Chatterjee
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Atish Roy Chowdhury
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Debapriya Mukherjee
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
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6
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Stranahan LW, Arenas-Gamboa AM. When the Going Gets Rough: The Significance of Brucella Lipopolysaccharide Phenotype in Host-Pathogen Interactions. Front Microbiol 2021; 12:713157. [PMID: 34335551 PMCID: PMC8319746 DOI: 10.3389/fmicb.2021.713157] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 06/22/2021] [Indexed: 01/18/2023] Open
Abstract
Brucella is a facultatively intracellular bacterial pathogen and the cause of worldwide zoonotic infections, infamous for its ability to evade the immune system and persist chronically within host cells. Despite the frequent association with attenuation in other Gram-negative bacteria, a rough lipopolysaccharide phenotype is retained by Brucella canis and Brucella ovis, which remain fully virulent in their natural canine and ovine hosts, respectively. While these natural rough strains lack the O-polysaccharide they, like their smooth counterparts, are able to evade and manipulate the host immune system by exhibiting low endotoxic activity, resisting destruction by complement and antimicrobial peptides, entering and trafficking within host cells along a similar pathway, and interfering with MHC-II antigen presentation. B. canis and B. ovis appear to have compensated for their roughness by alterations to their outer membrane, especially in regards to outer membrane proteins. B. canis, in particular, also shows evidence of being less proinflammatory in vivo, suggesting that the rough phenotype may be associated with an enhanced level of stealth that could allow these pathogens to persist for longer periods of time undetected. Nevertheless, much additional work is required to understand the correlates of immune protection against the natural rough Brucella spp., a critical step toward development of much-needed vaccines. This review will highlight the significance of rough lipopolysaccharide in the context of both natural disease and host–pathogen interactions with an emphasis on natural rough Brucella spp. and the implications for vaccine development.
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Affiliation(s)
- Lauren W Stranahan
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Angela M Arenas-Gamboa
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
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Roop RM, Barton IS, Hopersberger D, Martin DW. Uncovering the Hidden Credentials of Brucella Virulence. Microbiol Mol Biol Rev 2021; 85:e00021-19. [PMID: 33568459 PMCID: PMC8549849 DOI: 10.1128/mmbr.00021-19] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.
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Affiliation(s)
- R Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ian S Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Dariel Hopersberger
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Daniel W Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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Bialer MG, Sycz G, Muñoz González F, Ferrero MC, Baldi PC, Zorreguieta A. Adhesins of Brucella: Their Roles in the Interaction with the Host. Pathogens 2020; 9:E942. [PMID: 33198223 PMCID: PMC7697752 DOI: 10.3390/pathogens9110942] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/05/2020] [Indexed: 01/30/2023] Open
Abstract
A central aspect of Brucella pathogenicity is its ability to invade, survive, and replicate in diverse phagocytic and non-phagocytic cell types, leading to chronic infections and chronic inflammatory phenomena. Adhesion to the target cell is a critical first step in the invasion process. Several Brucella adhesins have been shown to mediate adhesion to cells, extracellular matrix components (ECM), or both. These include the sialic acid-binding proteins SP29 and SP41 (binding to erythrocytes and epithelial cells, respectively), the BigA and BigB proteins that contain an Ig-like domain (binding to cell adhesion molecules in epithelial cells), the monomeric autotransporters BmaA, BmaB, and BmaC (binding to ECM components, epithelial cells, osteoblasts, synoviocytes, and trophoblasts), the trimeric autotransporters BtaE and BtaF (binding to ECM components and epithelial cells) and Bp26 (binding to ECM components). An in vivo role has also been shown for the trimeric autotransporters, as deletion mutants display decreased colonization after oral and/or respiratory infection in mice, and it has also been suggested for BigA and BigB. Several adhesins have shown unipolar localization, suggesting that Brucella would express an adhesive pole. Adhesin-based vaccines may be useful to prevent brucellosis, as intranasal immunization in mice with BtaF conferred high levels of protection against oral challenge with B. suis.
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Affiliation(s)
- Magalí G. Bialer
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires 1405, Argentina; (M.G.B.); (G.S.)
| | - Gabriela Sycz
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires 1405, Argentina; (M.G.B.); (G.S.)
| | - Florencia Muñoz González
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina; (F.M.G.); (M.C.F.)
- Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Mariana C. Ferrero
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina; (F.M.G.); (M.C.F.)
- Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Pablo C. Baldi
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina; (F.M.G.); (M.C.F.)
- Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Angeles Zorreguieta
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires 1405, Argentina; (M.G.B.); (G.S.)
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
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Aerts JMFG, Artola M, van Eijk M, Ferraz MJ, Boot RG. Glycosphingolipids and Infection. Potential New Therapeutic Avenues. Front Cell Dev Biol 2019; 7:324. [PMID: 31867330 PMCID: PMC6908816 DOI: 10.3389/fcell.2019.00324] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022] Open
Abstract
Glycosphingolipids (GSLs), the main topic of this review, are a subclass of sphingolipids. With their glycans exposed to the extracellular space, glycosphingolipids are ubiquitous components of the plasma membrane of cells. GSLs are implicated in a variety of biological processes including specific infections. Several pathogens use GSLs at the surface of host cells as binding receptors. In addition, lipid-rafts in the plasma membrane of host cells may act as platform for signaling the presence of pathogens. Relatively common in man are inherited deficiencies in lysosomal glycosidases involved in the turnover of GSLs. The associated storage disorders (glycosphingolipidoses) show lysosomal accumulation of substrate(s) of the deficient enzyme. In recent years compounds have been identified that allow modulation of GSLs levels in cells. Some of these agents are well tolerated and already used to treat lysosomal glycosphingolipidoses. This review summarizes present knowledge on the role of GSLs in infection and subsequent immune response. It concludes with the thought to apply glycosphingolipid-lowering agents to prevent and/or combat infections.
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Affiliation(s)
| | - M Artola
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
| | - M van Eijk
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
| | - M J Ferraz
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
| | - R G Boot
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
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Otopathogenic Staphylococcus aureus Invades Human Middle Ear Epithelial Cells Primarily through Cholesterol Dependent Pathway. Sci Rep 2019; 9:10777. [PMID: 31346200 PMCID: PMC6658548 DOI: 10.1038/s41598-019-47079-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 06/26/2019] [Indexed: 01/20/2023] Open
Abstract
Chronic suppurative otitis media (CSOM) is one of the most common infectious diseases of the middle ear especially affecting children, leading to delay in language development and communication. Although Staphylococcus aureus is the most common pathogen associated with CSOM, its interaction with middle ear epithelial cells is not well known. In the present study, we observed that otopathogenic S. aureus has the ability to invade human middle ear epithelial cells (HMEECs) in a dose and time dependent manner. Scanning electron microscopy demonstrated time dependent increase in the number of S. aureus on the surface of HMEECs. We observed that otopathogenic S. aureus primarily employs a cholesterol dependent pathway to colonize HMEECs. In agreement with these findings, confocal microscopy showed that S. aureus colocalized with lipid rafts in HMEECs. The results of the present study provide new insights into the pathogenesis of S. aureus induced CSOM. The availability of in vitro cell culture model will pave the way to develop novel effective treatment modalities for CSOM beyond antibiotic therapy.
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Waldrop SG, Sriranganathan N. Intracellular invasion and survival of Brucella neotomae, another possible zoonotic Brucella species. PLoS One 2019; 14:e0213601. [PMID: 30943213 PMCID: PMC6447175 DOI: 10.1371/journal.pone.0213601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 02/25/2019] [Indexed: 12/17/2022] Open
Abstract
In 1967, Brucella neotomae was first isolated from Neotoma lepida, the dessert wood rat, in Utah. With little infection data since its discovery, the zoonotic potential of this Brucella species is largely unknown. Recent reports of isolation from human cerebrospinal fluid, along with current literature suggest that B. neotomae has the ability to infect various hosts and cell types. In this report we extend the knowledge of B. neotomae ATCC 23459’s intracellular invasion and survival abilities to a variety of cell lines through gentamicin protection assays. Some of the phagocytic and epithelial cell lines from various mammalian species represent characteristics of some cell types that could be encountered by Brucella in potential hosts. It was found that B. neotomae ATCC 23459 exhibits generally lower intracellular bacterial CFUs compared to the mouse-passaged strain of B. neotomae ATCC 23459, B. suis 1330, and B. abortus 2308. Ultimately, these observations provide a small piece of the puzzle in the investigation of the breadth of B. neotomae’s pathogenic potential.
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Affiliation(s)
- Steven Grant Waldrop
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Nammalwar Sriranganathan
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- * E-mail:
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Pujol M, Borie C, Montoya M, Ferreira A, Vernal R. Brucella canis induces canine CD4 + T cells multi-cytokine Th1/Th17 production via dendritic cell activation. Comp Immunol Microbiol Infect Dis 2018; 62:68-75. [PMID: 30711049 DOI: 10.1016/j.cimid.2018.11.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 11/23/2018] [Accepted: 11/27/2018] [Indexed: 01/18/2023]
Abstract
Brucella canis is a small intracellular Gram-negative bacterium that frequently leads to chronic infections highly resistant to antibiotic therapy in dogs. Also, it causes mild human brucellosis compared to other zoonotic Brucella spp. Herein we characterize the cellular immune response elicited by B. canis by analysing human and canine CD4+ T cells after stimulation with autologous monocyte-derived dendritic cells (MoDCs). Human and canine B. canis-primed MoDCs stimulated autologous CD4+ T cells; however, a Th1 response was triggered by human MoDCs, whereas canine MoDCs induced Th1/Th17 responses, with increased CD4+ T cells producing IFN-γ and IL-17A simultaneously. Each pattern of cellular response may contribute to host susceptibility, helping to understand the differences in B. canis virulence between these two hosts. In addition, other aspects of canine immunology are unveiled by highlighting the participation of IL-17A-producing canine MoDCs and CD4+ T cells producing IFN-γ and IL-17A.
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Affiliation(s)
- Myriam Pujol
- Program of Immunology, Institute of Biomedical Sciences ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile; Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile.
| | - Consuelo Borie
- Laboratory of Veterinary Bacteriology, Department of Animal Preventive Medicine, Faculty of Veterinary Sciences, Universidad de Chile, Santiago, Chile
| | - María Montoya
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Arturo Ferreira
- Program of Immunology, Institute of Biomedical Sciences ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
| | - Rolando Vernal
- Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile; Dentistry Unit, Faculty of Health Sciences, Universidad Autónoma de Chile, Santiago, Chile.
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Xu Y, Xu T, Zhang J. Efficient synthesis of a 6-deoxy-talose containing tetrasccharide found in Franconibacter helveticus LMG23732 T. Carbohydr Res 2018. [DOI: 10.1016/j.carres.2018.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Pujol M, Castillo F, Alvarez C, Rojas C, Borie C, Ferreira A, Vernal R. Variability in the response of canine and human dendritic cells stimulated with Brucella canis. Vet Res 2017; 48:72. [PMID: 29096717 PMCID: PMC5667440 DOI: 10.1186/s13567-017-0476-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 10/16/2017] [Indexed: 01/30/2023] Open
Abstract
Brucella canis is a small intracellular Gram-negative bacterium whose primary host is the dog, but it also can cause mild human brucellosis. One of the main causes of an inefficient immune response against other species of Brucella is their interaction with dendritic cells (DCs), which affects antigen presentation and impairs the development of an effective Th1 immune response. This study analysed the cytokine pattern production, by RT-qPCR and ELISA, in human and canine DCs against whole B. canis or its purified LPS. Human and canine DCs produced different patterns of cytokines after stimulation with B. canis. In particular, while human DCs produced a Th1-pattern of cytokines (IL-1β, IL-12, and TNF-α), canine cells produced both Th1 and Th17-related cytokines (IL-6, IL-12, IL-17, and IFN-γ). Thus, differences in susceptibility and pathogenicity between these two hosts could be explained, at least partly, by the distinct cytokine patterns observed in this study, where we propose that human DCs induce an effective Th1 immune response to control the infection, while canine DCs lead to a less effective immune response, with the activation of Th17-related response ineffective to control the B. canis infection.
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Affiliation(s)
- Myriam Pujol
- Doctoral Program in Agronomy Forestry and Veterinary Sciences, Faculty of Veterinary Sciences, Universidad de Chile, Santiago, Chile.,Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Francisca Castillo
- Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Carla Alvarez
- Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Camila Rojas
- Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Consuelo Borie
- Laboratory of Veterinary Bacteriology, Department of Animal Preventive Medicine, Faculty of Veterinary Sciences, Universidad de Chile, Santiago, Chile
| | - Arturo Ferreira
- Program of Immunology, Institute of Biomedical Sciences ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Rolando Vernal
- Periodontal Biology Laboratory, Faculty of Dentistry, Universidad de Chile, Santiago, Chile. .,Dentistry Unit, Faculty of Health Sciences, Universidad Autónoma de Chile, Santiago, Chile.
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15
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Abstract
Coxiella burnetii is an intracellular bacterial pathogen and a significant cause of culture-negative endocarditis in the United States. Upon infection, the nascent Coxiella phagosome fuses with the host endocytic pathway to form a large lysosome-like vacuole called the parasitophorous vacuole (PV). The PV membrane is rich in sterols, and drugs perturbing host cell cholesterol homeostasis inhibit PV formation and bacterial growth. Using cholesterol supplementation of a cholesterol-free cell model system, we found smaller PVs and reduced Coxiella growth as cellular cholesterol concentration increased. Further, we observed in cells with cholesterol a significant number of nonfusogenic PVs that contained degraded bacteria, a phenotype not observed in cholesterol-free cells. Cholesterol had no effect on axenic Coxiella cultures, indicating that only intracellular bacteria are sensitive to cholesterol. Live-cell microscopy revealed that both plasma membrane-derived cholesterol and the exogenous cholesterol carrier protein low-density lipoprotein (LDL) traffic to the PV. To test the possibility that increasing PV cholesterol levels affects bacterial survival, infected cells were treated with U18666A, a drug that traps cholesterol in lysosomes and PVs. U18666A treatment led to PVs containing degraded bacteria and a significant loss in bacterial viability. The PV pH was significantly more acidic in cells with cholesterol or cells treated with U18666A, and the vacuolar ATPase inhibitor bafilomycin blocked cholesterol-induced PV acidification and bacterial death. Additionally, treatment of infected HeLa cells with several FDA-approved cholesterol-altering drugs led to a loss of bacterial viability, a phenotype also rescued by bafilomycin. Collectively, these data suggest that increasing PV cholesterol further acidifies the PV, leading to Coxiella death. The intracellular Gram-negative bacterium Coxiella burnetii is a significant cause of culture-negative infectious endocarditis, which can be fatal if untreated. The existing treatment strategy requires prolonged antibiotic treatment, with a 10-year mortality rate of 19% in treated patients. Therefore, new clinical therapies are needed and can be achieved by better understanding C. burnetii pathogenesis. Upon infection of host cells, C. burnetii grows within a specialized replication niche, the parasitophorous vacuole (PV). Recent data have linked cholesterol to intracellular C. burnetii growth and PV formation, leading us to further decipher the role of cholesterol during C. burnetii-host interaction. We observed that increasing PV cholesterol concentration leads to increased acidification of the PV and bacterial death. Further, treatment with FDA-approved drugs that alter host cholesterol homeostasis also killed C. burnetii through PV acidification. Our findings suggest that targeting host cholesterol metabolism might prove clinically efficacious in controlling C. burnetii infection.
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Abstract
Intracellular bacterial pathogens have evolved to exploit the protected niche provided within the boundaries of a eukaryotic host cell. Upon entering a host cell, some bacteria can evade the adaptive immune response of its host and replicate in a relatively nutrient-rich environment devoid of competition from other host flora. Growth within a host cell is not without their hazards, however. Many pathogens enter their hosts through receptor-mediated endocytosis or phagocytosis, two intracellular trafficking pathways that terminate in a highly degradative organelle, the phagolysosome. This usually deadly compartment is maintained at a low pH and contains degradative enzymes and reactive oxygen species, resulting in an environment to which few bacterial species are adapted. Some intracellular pathogens, such as Shigella, Listeria, Francisella, and Rickettsia, escape the phagosome to replicate within the cytosol of the host cell. Bacteria that remain within a vacuole either alter the trafficking of their initial phagosomal compartment or adapt to survive within the harsh environment it will soon become. In this chapter, we focus on the mechanisms by which different vacuolar pathogens either evade lysosomal fusion, as in the case of Mycobacterium and Chlamydia, or allow interaction with lysosomes to varying degrees, such as Brucella and Coxiella, and their specific adaptations to inhabit a replicative niche.
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Toledo A, Benach JL. Hijacking and Use of Host Lipids by Intracellular Pathogens. Microbiol Spectr 2015; 3:10.1128/microbiolspec.VMBF-0001-2014. [PMID: 27337282 PMCID: PMC5790186 DOI: 10.1128/microbiolspec.vmbf-0001-2014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 12/14/2022] Open
Abstract
Intracellular bacteria use a number of strategies to survive, grow, multiply, and disseminate within the host. One of the most striking adaptations that intracellular pathogens have developed is the ability to utilize host lipids and their metabolism. Bacteria such as Anaplasma, Chlamydia, or Mycobacterium can use host lipids for different purposes, such as a means of entry through lipid rafts, building blocks for bacteria membrane formation, energy sources, camouflage to avoid the fusion of phagosomes and lysosomes, and dissemination. One of the most extreme examples of lipid exploitation is Mycobacterium, which not only utilizes the host lipid as a carbon and energy source but is also able to reprogram the host lipid metabolism. Likewise, Chlamydia spp. have also developed numerous mechanisms to reprogram lipids onto their intracellular inclusions. Finally, while the ability to exploit host lipids is important in intracellular bacteria, it is not an exclusive trait. Extracellular pathogens, including Helicobacter, Mycoplasma, and Borrelia, can recruit and metabolize host lipids that are important for their growth and survival.Throughout this chapter we will review how intracellular and extracellular bacterial pathogens utilize host lipids to enter, survive, multiply, and disseminate in the host.
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Affiliation(s)
- Alvaro Toledo
- Department of Molecular Genetics and Microbiology, Stony Brook University, Center for Infectious Diseases at the Center for Molecular Medicine, Stony Brook, NY 11794
| | - Jorge L Benach
- Department of Molecular Genetics and Microbiology, Stony Brook University, Center for Infectious Diseases at the Center for Molecular Medicine, Stony Brook, NY 11794
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18
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Brucella canis is an intracellular pathogen that induces a lower proinflammatory response than smooth zoonotic counterparts. Infect Immun 2015; 83:4861-70. [PMID: 26438796 DOI: 10.1128/iai.00995-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/29/2015] [Indexed: 01/18/2023] Open
Abstract
Canine brucellosis caused by Brucella canis is a disease of dogs and a zoonotic risk. B. canis harbors most of the virulence determinants defined for the genus, but its pathogenic strategy remains unclear since it has not been demonstrated that this natural rough bacterium is an intracellular pathogen. Studies of B. canis outbreaks in kennel facilities indicated that infected dogs displaying clinical signs did not present hematological alterations. A virulent B. canis strain isolated from those outbreaks readily replicated in different organs of mice for a protracted period. However, the levels of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-12 in serum were close to background levels. Furthermore, B. canis induced lower levels of gamma interferon, less inflammation of the spleen, and a reduced number of granulomas in the liver in mice than did B. abortus. When the interaction of B. canis with cells was studied ex vivo, two patterns were observed, a predominant scattered cell-associated pattern of nonviable bacteria and an infrequent intracellular replicative pattern of viable bacteria in a perinuclear location. The second pattern, responsible for the increase in intracellular multiplication, was dependent on the type IV secretion system VirB and was seen only if the inoculum used for cell infections was in early exponential phase. Intracellular replicative B. canis followed an intracellular trafficking route undistinguishable from that of B. abortus. Although B. canis induces a lower proinflammatory response and has a stealthier replication cycle, it still displays the pathogenic properties of the genus and the ability to persist in infected organs based on the ability to multiply intracellularly.
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Larsen AK, Nymo IH, Briquemont B, Sørensen KK, Godfroid J. Entrance and survival of Brucella pinnipedialis hooded seal strain in human macrophages and epithelial cells. PLoS One 2013; 8:e84861. [PMID: 24376851 PMCID: PMC3869908 DOI: 10.1371/journal.pone.0084861] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 11/19/2013] [Indexed: 11/19/2022] Open
Abstract
Marine mammal Brucella spp. have been isolated from pinnipeds (B. pinnipedialis) and cetaceans (B. ceti) from around the world. Although the zoonotic potential of marine mammal brucellae is largely unknown, reports of human disease exist. There are few studies of the mechanisms of bacterial intracellular invasion and multiplication involving the marine mammal Brucella spp. We examined the infective capacity of two genetically different B. pinnipedialis strains (reference strain; NTCT 12890 and a hooded seal isolate; B17) by measuring the ability of the bacteria to enter and replicate in cultured phagocytes and epithelial cells. Human macrophage-like cells (THP-1), two murine macrophage cell lines (RAW264.7 and J774A.1), and a human malignant epithelial cell line (HeLa S3) were challenged with bacteria in a gentamicin protection assay. Our results show that B. pinnipedialis is internalized, but is then gradually eliminated during the next 72 – 96 hours. Confocal microscopy revealed that intracellular B. pinnipedialis hooded seal strain colocalized with lysosomal compartments at 1.5 and 24 hours after infection. Intracellular presence of B. pinnipedialis hooded seal strain was verified by transmission electron microscopy. By using a cholesterol-scavenging lipid inhibitor, entrance of B. pinnipedialis hooded seal strain in human macrophages was significantly reduced by 65.8 % (± 17.3), suggesting involvement of lipid-rafts in intracellular entry. Murine macrophages invaded by B. pinnipedialis do not release nitric oxide (NO) and intracellular bacterial presence does not induce cell death. In summary, B. pinnipedialis hooded seal strain can enter human and murine macrophages, as well as human epithelial cells. Intracellular entry of B. pinnipedialis hooded seal strain involves, but seems not to be limited to, lipid-rafts in human macrophages. Brucella pinnipedialis does not multiply or survive for prolonged periods intracellulary.
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Affiliation(s)
- Anett K. Larsen
- Section for Arctic Veterinary Medicine, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Tromsø, Norway
- The Fram Centre, High North Research Centre for Climate and the Environment, Tromsø, Norway
- * E-mail:
| | - Ingebjørg H. Nymo
- Section for Arctic Veterinary Medicine, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Tromsø, Norway
- The Fram Centre, High North Research Centre for Climate and the Environment, Tromsø, Norway
| | - Benjamin Briquemont
- Faculty of Science, Catholic University of Louvain, Louvain-la-Neuve, Belgium
| | - Karen K. Sørensen
- Vascular Biology Research Group, Department of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Jacques Godfroid
- Section for Arctic Veterinary Medicine, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Tromsø, Norway
- The Fram Centre, High North Research Centre for Climate and the Environment, Tromsø, Norway
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20
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Gomez G, Adams LG, Rice-Ficht A, Ficht TA. Host-Brucella interactions and the Brucella genome as tools for subunit antigen discovery and immunization against brucellosis. Front Cell Infect Microbiol 2013; 3:17. [PMID: 23720712 PMCID: PMC3655278 DOI: 10.3389/fcimb.2013.00017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 04/26/2013] [Indexed: 01/18/2023] Open
Abstract
Vaccination is the most important approach to counteract infectious diseases. Thus, the development of new and improved vaccines for existing, emerging, and re-emerging diseases is an area of great interest to the scientific community and general public. Traditional approaches to subunit antigen discovery and vaccine development lack consideration for the critical aspects of public safety and activation of relevant protective host immunity. The availability of genomic sequences for pathogenic Brucella spp. and their hosts have led to development of systems-wide analytical tools that have provided a better understanding of host and pathogen physiology while also beginning to unravel the intricacies at the host-pathogen interface. Advances in pathogen biology, host immunology, and host-agent interactions have the potential to serve as a platform for the design and implementation of better-targeted antigen discovery approaches. With emphasis on Brucella spp., we probe the biological aspects of host and pathogen that merit consideration in the targeted design of subunit antigen discovery and vaccine development.
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Affiliation(s)
- Gabriel Gomez
- Department of Veterinary Pathobiology, Texas A&M University College Station, TX 77843, USA.
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Sá JC, Silva TMA, Costa EA, Silva APC, Tsolis RM, Paixão TA, Carvalho Neta AV, Santos RL. The virB-encoded type IV secretion system is critical for establishment of infection and persistence of Brucella ovis infection in mice. Vet Microbiol 2012; 159:130-40. [PMID: 22483850 DOI: 10.1016/j.vetmic.2012.03.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 03/08/2012] [Accepted: 03/10/2012] [Indexed: 12/13/2022]
Abstract
Brucella spp. are gram-negative intracellular bacterial pathogens that cause chronic infections. Brucella virulence factors include a type IV secretion system (T4SS) and its lipopolysaccharide (LPS), which are essential for persistence. However, the role of the virB-encoded T4SS has not been investigated in naturally rough Brucella species such as Brucella ovis. In this study, male 6-week old BALBc mice were infected with B. ovis, Brucella abortus, and their respective ΔvirB2 mutant strains. During early infection, B. ovis and B. abortus wild type strains were similarly recovered from spleen. Interestingly, in contrast to ΔvirB2 B. abortus that was recovered at similar levels when compared to the wild type strain, the ΔvirB2 B. ovis was markedly attenuated as early as 24h post infection (hpi). The ΔvirB2 B. ovis was unable to survive and multiply in murine peritoneal macrophages and extracellularly within the peritoneal cavity at 12 and 24 hpi with lower splenic colonization than the parental strain at 6, 12 and 24 hpi. In contrast, wild type B. abortus and ΔvirB2 B. abortus had a similar kinetics of infection in this model. As expected, the T4SS was essential for intracellular replication of smooth and rough strains in RAW macrophages at 48 hpi. These results suggest that T4SS is important for survival of B. ovis in murine model, and that a T4SS deficient B. ovis strain is cleared at earlier stages of infection when compared to a similar B. abortus mutant.
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Affiliation(s)
- Joicy C Sá
- Departamento de Clínica e Cirurgia Veterinária, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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22
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von Bargen K, Gorvel JP, Salcedo SP. Internal affairs: investigating the Brucella intracellular lifestyle. FEMS Microbiol Rev 2012; 36:533-62. [PMID: 22373010 DOI: 10.1111/j.1574-6976.2012.00334.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 01/10/2012] [Accepted: 02/16/2012] [Indexed: 01/18/2023] Open
Abstract
Bacteria of the genus Brucella are Gram-negative pathogens of several animal species that cause a zoonotic disease in humans known as brucellosis or Malta fever. Within their hosts, brucellae reside within different cell types where they establish a replicative niche and remain protected from the immune response. The aim of this article is to discuss recent advances in the field in the specific context of the Brucella intracellular 'lifestyle'. We initially discuss the different host cell targets and their relevance during infection. As it represents the key to intracellular replication, the focus is then set on the maturation of the Brucella phagosome, with particular emphasis on the Brucella factors that are directly implicated in intracellular trafficking and modulation of host cell signalling pathways. Recent data on the role of the type IV secretion system are discussed, novel effector molecules identified and how some of them impact on trafficking events. Current knowledge on Brucella gene regulation and control of host cell death are summarized, as they directly affect intracellular persistence. Understanding how Brucella molecules interplay with their host cell targets to modulate cellular functions and establish the intracellular niche will help unravel how this pathogen causes disease.
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Affiliation(s)
- Kristine von Bargen
- Faculté de Sciences de Luminy, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, UM 2, Marseille Cedex, France
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Quorum-sensing and BvrR/BvrS regulation, the type IV secretion system, cyclic glucans, and BacA in the virulence of Brucella ovis: similarities to and differences from smooth brucellae. Infect Immun 2012; 80:1783-93. [PMID: 22392933 DOI: 10.1128/iai.06257-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella ovis is a rough bacterium--lacking O-polysaccharide chains in the lipopolysaccharide--that is virulent in its natural host and whose virulence mechanisms remain almost unexplored. In a search for additional traits that distinguish B. ovis from smooth Brucella, which require O-polysaccharide chains for virulence, we have analyzed the significance in B. ovis of the main virulence factors described for smooth Brucella. Attempts to obtain strains of virulent B. ovis strain PA that are mutated in the BvrR/BvrS two-component regulatory system were unsuccessful, suggesting the requirement of that system for in vitro survival, while the inactivation of bacA--in contrast to the results seen with smooth Brucella--did not affect splenic colonization in mice or behavior in J774.A1 murine macrophages. Defects in the synthesis of cyclic ß-1,2 glucans reduced the uptake of B. ovis PA in macrophages and, although the intracellular multiplication rate was unaffected, led to attenuation in mice. Growth of strains with mutations in the type IV secretion system (encoded by the virB operon) and the quorum-sensing-related regulator VjbR was severely attenuated in the mouse model, and although the mutant strains internalized like the parental strain in J774.A1 murine macrophages, they were impaired for intracellular replication. As described for B. melitensis, VjbR regulates the transcription of the virB operon positively, and the N-dodecanoyl-dl-homoserine lactone (C(12)-HSL) autoinducer abrogates this effect. In contrast, no apparent VjbR-mediated regulation of the fliF flagellar gene was observed in B. ovis, probably due to the two deletions detected upstream of fliF. These results, together with others reported in the text, point to similarities between rough virulent B. ovis and smooth Brucella species as regards virulence but also reveal distinctive traits that could be related to the particular pathogenicity and host tropism characteristics of B. ovis.
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