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Santecchia I, Ferrer MF, Vieira ML, Gómez RM, Werts C. Phagocyte Escape of Leptospira: The Role of TLRs and NLRs. Front Immunol 2020; 11:571816. [PMID: 33123147 PMCID: PMC7573490 DOI: 10.3389/fimmu.2020.571816] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/16/2020] [Indexed: 12/21/2022] Open
Abstract
The spirochetal bacteria Leptospira spp. are causative agents of leptospirosis, a globally neglected and reemerging zoonotic disease. Infection with these pathogens may lead to an acute and potentially fatal disease but also to chronic asymptomatic renal colonization. Both forms of disease demonstrate the ability of leptospires to evade the immune response of their hosts. In this review, we aim first to recapitulate the knowledge and explore the controversial data about the opsonization, recognition, intracellular survival, and killing of leptospires by scavenger cells, including platelets, neutrophils, macrophages, and dendritic cells. Second, we will summarize the known specificities of the recognition or escape of leptospire components (the so-called microbial-associated molecular patterns; MAMPs) by the pattern recognition receptors (PRRs) of the Toll-like and NOD-like families. These PRRs are expressed by phagocytes, and their stimulation by MAMPs triggers pro-inflammatory cytokine and chemokine production and bactericidal responses, such as antimicrobial peptide secretion and reactive oxygen species production. Finally, we will highlight recent studies suggesting that boosting or restoring phagocytic functions by treatments using agonists of the Toll-like or NOD receptors represents a novel prophylactic strategy and describe other potential therapeutic or vaccine strategies to combat leptospirosis.
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Affiliation(s)
- Ignacio Santecchia
- Institut Pasteur, Microbiology Department, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France.,CNRS, UMR 2001 Microbiologie intégrative et Moléculaire, Paris, France.,INSERM, Equipe Avenir, Paris, France.,Université de Paris, Sorbonne Paris Cité, Paris, France
| | - María Florencia Ferrer
- Laboratorio de Virus Animales, Instituto de Biotecnología y Biología Molecular, CONICET-Universidad Nacional de La Plata, La Plata, Argentina
| | - Monica Larucci Vieira
- Departamento de Microbiologia, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Ricardo Martín Gómez
- Laboratorio de Virus Animales, Instituto de Biotecnología y Biología Molecular, CONICET-Universidad Nacional de La Plata, La Plata, Argentina
| | - Catherine Werts
- Institut Pasteur, Microbiology Department, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France.,CNRS, UMR 2001 Microbiologie intégrative et Moléculaire, Paris, France
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Passalia FJ, Carvalho E, Heinemann MB, Vieira ML, Nascimento ALTO. The Leptospira interrogans LIC10774 is a multifunctional surface protein that binds calcium and interacts with host components. Microbiol Res 2020; 235:126470. [PMID: 32247916 DOI: 10.1016/j.micres.2020.126470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/13/2020] [Accepted: 03/15/2020] [Indexed: 02/06/2023]
Abstract
Leptospirosis is a global re-emerging zoonosis, caused by pathogenic bacteria of the genus Leptospira. Humans are infected mainly through contact with contaminated water or soil. The understanding of the molecular mechanisms of leptospirosis through the characterization of unknown outer membrane proteins may contribute to the development of new treatments, diagnostic methods and vaccines. We have identified using bioinformatics analysis a protein that is encoded by the gene LIC10774, predicted to be localized at the leptospiral outer membrane and exhibit beta-roll folding. Surface exposure was confirmed by flow cytometry, ELISA and immunofluorescence-based confocal microscopy. Through circular dichroism spectroscopy and hydrophobic dye binding we have shown that rLIC10774 binds calcium ions, which imposes changes to secondary and tertiary structures. The recombinant protein was capable of binding to several host extracellular matrix and serum components. Therefore, we describe LIC10774 as a calcium-binding protein exposed in the outer surface of pathogenic leptospires with possible multifunctional roles in adhesion to host tissues, evasion of the immune system and participation in dissemination processes during leptospirosis. In addition, we hypothesize that the calcium binding is important for temperature-dependent functional roles during leptospirosis.
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Affiliation(s)
- Felipe José Passalia
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, 05503-900, São Paulo, Brazil; Programa de Pós-Graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-900, São Paulo, Brazil
| | - Eneas Carvalho
- Laboratório de Bacteriologia, Instituto Butantan, 05503-900, São Paulo, Brazil
| | - Marcos Bryan Heinemann
- Laboratório de Zoonoses Bacterianas, Faculdade de Medicina Veterinária e Zootecnia, Universidade de Sao Paulo, Brazil
| | - Mônica Larucci Vieira
- Departamento de Microbiologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais (UFMG), Minas Gerais, Brazil.
| | - Ana Lucia T O Nascimento
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, 05503-900, São Paulo, Brazil; Programa de Pós-Graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-900, São Paulo, Brazil.
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3
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Luo X, Zhang X, Gan L, Zhou C, Zhao T, Zeng T, Liu S, Xiao Y, Yu J, Zhao F. The outer membrane protein Tp92 of Treponema pallidum induces human mononuclear cell death and IL-8 secretion. J Cell Mol Med 2018; 22:6039-6054. [PMID: 30596396 PMCID: PMC6237608 DOI: 10.1111/jcmm.13879] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/30/2018] [Indexed: 12/19/2022] Open
Abstract
Treponema pallidum is the pathogen that causes syphilis, a sexually transmitted disease; however, the pathogenic mechanism of this organism remains unclear. Tp92 is the only T. pallidum outer membrane protein that has structural features similar to the outer membrane proteins of other Gram-negative bacteria, but the exact functions of this protein remain unknown. In the present study, we demonstrated that the recombinant Tp92 protein can induce human mononuclear cell death. Tp92 mediated the human monocytic cell line derived from an acute monicytic leukemia patient (THP-1) cell death by recognizing CD14 and/or TLR2 on cell surfaces. After the stimulation of THP-1 cells by the Tp92 protein, Tp92 may induce atypical pyroptosis of THP-1 cells via the pro-caspase-1 pathway. Meanwhile, this protein caused the apoptosis of THP-1 cells via the receptor-interacting protein kinase 1/caspase-8/aspase-3 pathway. Tp92 reduced the number of monocytes among peripheral blood mononuclear cells. Interestingly, further research showed that Tp92 failed to increase the tumour necrosis factor-α, interleukin (IL)-1β, IL-6, IL-10, IL-18 and monocyte chemotactic protein 1 (MCP)-1 levels but slightly elevated the IL-8 levels via the Nuclear Factor (NF)-κB pathway in THP-1 cells. The data suggest that Tp92 recognizes CD14 and TLR2, transfers the signal to a downstream pathway, and activates NF-κB to mediate the production of IL-8. This mechanism may help T. pallidum escape recognition and elimination by the host innate immune system.
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MESH Headings
- Antigens, Surface/genetics
- Bacterial Proteins/genetics
- Caspase 1/genetics
- Cell Death/genetics
- Cell Line, Tumor
- Cytokines/genetics
- Host-Pathogen Interactions/genetics
- Humans
- Interleukin-8/genetics
- Leukemia, Monocytic, Acute/genetics
- Leukemia, Monocytic, Acute/microbiology
- Leukemia, Monocytic, Acute/pathology
- Leukocytes, Mononuclear/microbiology
- Leukocytes, Mononuclear/pathology
- Lipopolysaccharide Receptors/genetics
- NF-kappa B/genetics
- Recombinant Proteins/genetics
- Signal Transduction/genetics
- Syphilis/genetics
- Syphilis/microbiology
- Syphilis/pathology
- Toll-Like Receptor 2/genetics
- Treponema pallidum/genetics
- Treponema pallidum/pathogenicity
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Affiliation(s)
- Xi Luo
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
| | - Xiaohong Zhang
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
- Department of Histology and EmbryologySchool of MedicineUniversity of South ChinaHengyangChina
| | - Lin Gan
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
| | - Chenglong Zhou
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
| | - Tie Zhao
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
| | - Tiebing Zeng
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
| | - Shuangquan Liu
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
- Department of Clinical LaboratoryThe First Affiliated Hospital of University of South ChinaHengyangChina
| | - Yongjian Xiao
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
- Department of Clinical LaboratoryThe Second Affiliated Hospital of University of South ChinaHengyangChina
| | - Jian Yu
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
| | - Feijun Zhao
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan ProvinceCollaborative Innovation Center for New Molecular Drug ResearchUniversity of South ChinaHengyangChina
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Ferrer MF, Scharrig E, Charo N, Rípodas AL, Drut R, Carrera Silva EA, Nagel A, Nally JE, Montes de Oca DP, Schattner M, Gómez RM. Macrophages and Galectin 3 Control Bacterial Burden in Acute and Subacute Murine Leptospirosis That Determines Chronic Kidney Fibrosis. Front Cell Infect Microbiol 2018; 8:384. [PMID: 30425972 PMCID: PMC6218566 DOI: 10.3389/fcimb.2018.00384] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/11/2018] [Indexed: 12/15/2022] Open
Abstract
Previous studies have suggested that macrophages may contribute to acute Leptospira dissemination, as well as having a major role in kidney fibrosis. Our aim was to characterize the role of macrophages and galectin 3 (Gal-3) on the survival, clinical course, bacterial burden, interstitial nephritis, and chronic kidney fibrosis in Leptospira interrogans serovar Copenhageni (LIC)-induced experimental murine leptospirosis. C57BL/6J mice depleted of macrophages by liposome-encapsulated clodronate treatment and infected with LIC presented a higher bacterial burden, had reduced subacute nephritis and enhanced chronic kidney fibrosis relative to untreated, infected mice. Moreover, LIC infection in mice whose Gal-3 was disrupted (Lgals3−/–) had a higher bacterial burden and enhanced subacute nephritis and chronic kidney fibrosis when compared to C57BL/6J wild-type mice. Chronic fibrosis did not correlate with higher transcription levels of TGF-β1 or IL-13 in the kidneys. Kidney fibrosis was found in chronically infected rats as well as in wild infected rats. On the other hand, human fibroblast cultures exhibited enhanced differentiation to myofibroblasts after treatment with LIC. Our results demonstrate that macrophages and Gal-3 play a critical role in controlling the LIC burden but has a minor role in subsequent fibrosis. Instead, kidney fibrosis was better correlated with bacterial burden. Taken together, our results do not support a role for macrophages to disseminate leptospires during acute infection, nor in chronic kidney fibrosis.
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Affiliation(s)
- María F Ferrer
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, UNLP-CONICET, La Plata, Argentina
| | - Emilia Scharrig
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, UNLP-CONICET, La Plata, Argentina
| | - Nancy Charo
- Laboratory of Experimental Thrombosis, Institute of Experimental Medicine, National Academy of Medicine-CONICET, Buenos Aires, Argentina
| | | | - Ricardo Drut
- Division of Pathology, Children Hospital "Superiora Sor María Ludovica", La Plata, Argentina
| | - Eugenio A Carrera Silva
- Laboratory of Experimental Thrombosis, Institute of Experimental Medicine, National Academy of Medicine-CONICET, Buenos Aires, Argentina
| | - Ariel Nagel
- Biotechnology Institute, National Institute of Agricultural Technology (INTA-CONICET), Buenos Aires, Argentina
| | - Jarlath E Nally
- Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, United States
| | - Daniela P Montes de Oca
- Ecology, Genetics and Evolution Department, Exact and Natural Sciences Faculty, and Ecology, Genetics and Evolution Institute of Buenos Aires, UBA-CONICET, Buenos Aires, Argentina
| | - Mirta Schattner
- Laboratory of Experimental Thrombosis, Institute of Experimental Medicine, National Academy of Medicine-CONICET, Buenos Aires, Argentina
| | - Ricardo M Gómez
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, UNLP-CONICET, La Plata, Argentina
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5
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Recent findings related to immune responses against leptospirosis and novel strategies to prevent infection. Microbes Infect 2018; 20:578-588. [PMID: 29452258 DOI: 10.1016/j.micinf.2018.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 12/11/2022]
Abstract
What are the new approaches and emerging ideas to prevent leptospirosis, a neglected bacterial re-emerging zoonotic disease? How do Leptospira interrogans escape the host defenses? We aim here to review and discuss the most recent literature that provides some answers to these questions, in particular data related to a better understanding of adaptive and innate immunity towards leptospires, and design of vaccines. This is an opinion paper, not a comprehensive review. We will try to highlight the new strategies and technologies boosting the search for drugs and vaccines. We will also address the bottlenecks and difficulties impairing the search for efficient vaccines and the many gaps in our knowledge of immunity against leptospirosis. Finally, we aim to delineate how Leptospira spp. escape the innate immune responses of Toll-Like receptors (TLR) and Nod-Like receptors (NLR). The rational use of TLR and NLR agonists as adjuvants could be key to design future vaccines against pathogenic leptospires.
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6
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Christodoulides A, Boyadjian A, Kelesidis T. Spirochetal Lipoproteins and Immune Evasion. Front Immunol 2017; 8:364. [PMID: 28424696 PMCID: PMC5372817 DOI: 10.3389/fimmu.2017.00364] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 03/14/2017] [Indexed: 12/28/2022] Open
Abstract
Spirochetes are a major threat to public health. However, the exact pathogenesis of spirochetal diseases remains unclear. Spirochetes express lipoproteins that often determine the cross talk between the host and spirochetes. Lipoproteins are pro-inflammatory, modulatory of immune responses, and enable the spirochetes to evade the immune system. In this article, we review the modulatory effects of spirochetal lipoproteins related to immune evasion. Understanding lipoprotein-induced immunomodulation will aid in elucidating innate pathogenesis processes and subsequent adaptive mechanisms potentially relevant to spirochetal disease vaccine development and treatment.
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Affiliation(s)
- Alexei Christodoulides
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Ani Boyadjian
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Theodoros Kelesidis
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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7
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Leptospira surface adhesin (Lsa21) induces Toll like receptor 2 and 4 mediated inflammatory responses in macrophages. Sci Rep 2016; 6:39530. [PMID: 27996041 PMCID: PMC5172228 DOI: 10.1038/srep39530] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/23/2016] [Indexed: 12/18/2022] Open
Abstract
Leptospirosis is zoonotic and emerging infectious disease of global importance. Little is understood about Leptospira pathogenesis and host immune response. In the present work we have investigated how Leptospira modulates the host innate immune response mediated by Toll-like receptors (TLRs) via surface exposed proteins. We screened Leptospira outer membrane/surface proteins for their ability to activate/inhibit TLR2/4 signaling in HEK293 cell lines. Of these the 21 kDa Leptospira surface adhesin, Lsa21 had strong TLR2 and TLR4 activity leading to production of proinflammatory cytokines and expression of costimulatory molecules in mouse macrophages. This activity of Lsa21 on innate response was dependent on activation of mitogen activated protein kinases (MAPKs) via stimulating the rapid phosphorylation of p38, JNK and activation of transcription factor NF-κB. Additionally, neutralizing antibodies against TLR2 and TLR4 significantly inhibited cytokine secretion and attenuated Lsa21 induced phosphorylation of p38 and JNK. Furthermore, Lsa21 induced cytokine levels were significantly lower in TLR2-/- and TLR4-/- than in wild type mouse macrophage cell lines. Confocal microscopy and molecular docking confirmed that Lsa21 interacted with both TLR2 and TLR4. These results indicate that Lsa21 is a potent TLR2 and TLR4 agonist that induces strong innate response and may play important role in Leptospira pathogenesis.
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8
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Tong SM, Chen Y, Ying SH, Feng MG. Three DUF1996 Proteins Localize in Vacuoles and Function in Fungal Responses to Multiple Stresses and Metal Ions. Sci Rep 2016; 6:20566. [PMID: 26839279 PMCID: PMC4738358 DOI: 10.1038/srep20566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/07/2016] [Indexed: 12/22/2022] Open
Abstract
Many annotated fungal genomes harbour high proportions of hypothetical proteins with or without domains of unknown function (DUF). Here, three novel proteins (342−497 amino acids), each containing only a single large DUF1996 (231−250 residues) region with highly conserved head (DPIXXP) and tail (HXDXXXGW) signatures, were expressed as eGFP-tagged fusion proteins and shown to specifically localize in the vacuoles of Beauveria bassiana, a filamentous fungal entomopathogen; therefore, these proteins were named vacuole-localized proteins (VLPs). The VLPs have one to three homologues in other entomopathogenic or non-entomopathogenic filamentous fungi but no homologues in yeasts. The large DUF1996 regions can be formulated as D-X4-P-X5–6-H-X-H-X3-G-X25–26-D-X-S-X-YW-X-P-X123–203-CP-X39–48-H-X-D-X3-GW; the identical residues likely involve in a proton antiport system for intracellular homeostasis. Single deletions of three VLP-coding genes (vlp1–3) increased fungal sensitivities to cell wall perturbation, high osmolarity, oxidation, and several metal ions. Conidial thermotolerance decreased by ~11% in two Δvlp mutants, and UV-B resistance decreased by 41−57% in three Δvlp mutants. All the changes were restored by targeted gene complementation. However, the deletions did not influence fungal growth, conidiation, virulence or Cu2+ sensitivity. Our findings unveiled a role for the DUF1996 regions of three B. bassiana VLPs in the regulation of multiple stress responses and environmental adaptation.
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Affiliation(s)
- Sen-Miao Tong
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, People's Republic of China
| | - Ying Chen
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, People's Republic of China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, People's Republic of China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, People's Republic of China
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9
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Eshghi A, Pappalardo E, Hester S, Thomas B, Pretre G, Picardeau M. Pathogenic Leptospira interrogans exoproteins are primarily involved in heterotrophic processes. Infect Immun 2015; 83:3061-73. [PMID: 25987703 PMCID: PMC4496612 DOI: 10.1128/iai.00427-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/11/2015] [Indexed: 12/19/2022] Open
Abstract
Leptospirosis is a life-threatening and emerging zoonotic disease with a worldwide annual occurrence of more than 1 million cases. Leptospirosis is caused by spirochetes belonging to the genus Leptospira. The mechanisms of disease manifestation in the host remain elusive, and the roles of leptospiral exoproteins in these processes have yet to be determined. Our aim in this study was to assess the composition and quantity of exoproteins of pathogenic Leptospira interrogans and to construe how these proteins contribute to disease pathogenesis. Label-free quantitative mass spectrometry of proteins obtained from Leptospira spirochetes cultured in vitro under conditions mimicking infection identified 325 exoproteins. The majority of these proteins are conserved in the nonpathogenic species Leptospira biflexa, and proteins involved in metabolism and energy-generating functions were overrepresented and displayed the highest relative abundance in culture supernatants. Conversely, proteins of unknown function, which represent the majority of pathogen-specific proteins (presumably involved in virulence mechanisms), were underrepresented. Characterization of various L. interrogans exoprotein mutants in the animal infection model revealed host mortality rates similar to those of hosts infected with wild-type L. interrogans. Collectively, these results indicate that pathogenic Leptospira exoproteins primarily function in heterotrophic processes (the processes by which organisms utilize organic substances as nutrient sources) to maintain the saprophytic lifestyle rather than the virulence of the bacteria. The underrepresentation of proteins homologous to known virulence factors, such as toxins and effectors in the exoproteome, also suggests that disease manifesting from Leptospira infection is likely caused by a combination of the primary and potentially moonlight functioning of exoproteins.
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Affiliation(s)
- Azad Eshghi
- Institut Pasteur, Biology of Spirochetes Unit, Paris, France
| | - Elisa Pappalardo
- University of Oxford, Sir William Dunn School of Pathology, Oxford, United Kingdom
| | - Svenja Hester
- University of Oxford, Sir William Dunn School of Pathology, Oxford, United Kingdom
| | - Benjamin Thomas
- University of Oxford, Sir William Dunn School of Pathology, Oxford, United Kingdom
| | - Gabriela Pretre
- Institut Pasteur, Biology of Spirochetes Unit, Paris, France
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Scharrig E, Carestia A, Ferrer MF, Cédola M, Pretre G, Drut R, Picardeau M, Schattner M, Gómez RM. Neutrophil Extracellular Traps are Involved in the Innate Immune Response to Infection with Leptospira. PLoS Negl Trop Dis 2015; 9:e0003927. [PMID: 26161745 PMCID: PMC4498591 DOI: 10.1371/journal.pntd.0003927] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/20/2015] [Indexed: 12/30/2022] Open
Abstract
NETosis is a process by which neutrophils extrude their DNA together with bactericidal proteins that trap and/or kill pathogens. In the present study, we evaluated the ability of Leptospira spp. to induce NETosis using human ex vivo and murine in vivo models. Microscopy and fluorometric studies showed that incubation of human neutrophils with Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 (LIC) resulted in the release of DNA extracellular traps (NETs). The bacteria number, pathogenicity and viability were relevant factors for induction of NETs, but bacteria motility was not. Entrapment of LIC in the NETs resulted in LIC death; however, pathogenic but not saprophytic Leptospira sp. exerted nuclease activity and degraded DNA. Mice infected with LIC showed circulating NETs after 2 days post-infection (dpi). Depletion of neutrophils with mAb1A8 significantly reduced the amount of intravascular NETs in LIC-infected mice, increasing bacteremia at 3 dpi. Although there was a low bacterial burden, scarce neutrophils and an absence of inflammation in the early stages of infection in the kidney and liver, at the beginning of the leptospiruric phase, the bacterial burden was significantly higher in kidneys of neutrophil-depleted-mice compared to non-depleted and infected mice. Surprisingly, interstitial nephritis was of similar intensity in both groups of infected mice. Taken together, these data suggest that LIC triggers NETs, and that the intravascular formation of these DNA traps appears to be critical not only to prevent early leptospiral dissemination but also to preclude further bacterial burden. Neutrophils extracellular traps (NETs) are a relatively novel pathogen-killing mechanism for extracellular microbes independent of phagocytic uptake and degranulation. Although it was originally proposed that NETs are formed exclusively in tissues at sites of infection, NETs have also been found within blood vessels where they ensnare microbes in circulation during sepsis. Leptospirosis is a global zoonosis that has become prevalent in slum areas, where its diagnosis and treatment may be overlooked. Here, for the first time, we characterized NETs formation as a result of Leptospira spp. stimulus. We also showed that mice lacking neutrophils exhibit early reduced levels of circulating NETs, but higher bacteremia, a fact that was later associated with higher bacterial burden in kidney. The present results demonstrate that Leptospira spp. can trigger NET formation and that this innate immune mechanism can play a role in the pathogenesis of leptospirosis.
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Affiliation(s)
- Emilia Scharrig
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, CCT-La Plata, CONICET-UNLP, Buenos Aires, Argentina
| | - Agostina Carestia
- Laboratory of Experimental Thrombosis, Institute of Experimental Medicine, CONICET-National Academy of Medicine, Buenos Aires, Argentina
| | - María F. Ferrer
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, CCT-La Plata, CONICET-UNLP, Buenos Aires, Argentina
| | - Maia Cédola
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, CCT-La Plata, CONICET-UNLP, Buenos Aires, Argentina
| | - Gabriela Pretre
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, CCT-La Plata, CONICET-UNLP, Buenos Aires, Argentina
| | - Ricardo Drut
- Division of Pathology, Children Hospital “Superiora Sor María Ludovica”, La Plata, Argentina
- Cátedra de Patología “A”, Facultad de Medicina, Universidad Nacional de La Plata, La Plata, Argentina
| | | | - Mirta Schattner
- Laboratory of Experimental Thrombosis, Institute of Experimental Medicine, CONICET-National Academy of Medicine, Buenos Aires, Argentina
- * E-mail: (MS); (RMG)
| | - Ricardo M. Gómez
- Laboratory of Animal Viruses, Institute of Biotechnology and Molecular Biology, CCT-La Plata, CONICET-UNLP, Buenos Aires, Argentina
- * E-mail: (MS); (RMG)
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11
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Decay-accelerating factor 1 deficiency exacerbates leptospiral-induced murine chronic nephritis and renal fibrosis. PLoS One 2014; 9:e102860. [PMID: 25032961 PMCID: PMC4102560 DOI: 10.1371/journal.pone.0102860] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 06/24/2014] [Indexed: 01/27/2023] Open
Abstract
Leptospirosis is a global zoonosis caused by pathogenic Leptospira, which can colonize the proximal renal tubules and persist for long periods in the kidneys of infected hosts. Here, we characterized the infection of C57BL/6J wild-type and Daf1−/− mice, which have an enhanced host response, with a virulent Leptospira interrogans strain at 14 days post-infection, its persistence in the kidney, and its link to kidney fibrosis at 90 days post-infection. We found that Leptospira interrogans can induce acute moderate nephritis in wild-type mice and is able to persist in some animals, inducing fibrosis in the absence of mortality. In contrast, Daf1−/− mice showed acute mortality, with a higher bacterial burden. At the chronic stage, Daf1−/− mice showed greater inflammation and fibrosis than at 14 days post-infection and higher levels at all times than the wild-type counterpart. Compared with uninfected mice, infected wild-type mice showed higher levels of IL-4, IL-10 and IL-13, with similar levels of α-smooth muscle actin, galectin-3, TGF-β1, IL-17, IFN-γ, and lower IL-12 levels at 90 days post-infection. In contrast, fibrosis in Daf1−/− mice was accompanied by high expression of α-smooth muscle actin, galectin-3, IL-10, IL-13, and IFN-γ, similar levels of TGF-β1, IL-12, and IL-17 and lower IL-4 levels. This study demonstrates the link between Leptospira-induced murine chronic nephritis with renal fibrosis and shows a protective role of Daf1.
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Kelesidis T. The Cross-Talk between Spirochetal Lipoproteins and Immunity. Front Immunol 2014; 5:310. [PMID: 25071771 PMCID: PMC4075078 DOI: 10.3389/fimmu.2014.00310] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 06/17/2014] [Indexed: 12/11/2022] Open
Abstract
Spirochetal diseases such as syphilis, Lyme disease, and leptospirosis are major threats to public health. However, the immunopathogenesis of these diseases has not been fully elucidated. Spirochetes interact with the host through various structural components such as lipopolysaccharides (LPS), surface lipoproteins, and glycolipids. Although spirochetal antigens such as LPS and glycolipids may contribute to the inflammatory response during spirochetal infections, spirochetes such as Treponema pallidum and Borrelia burgdorferi lack LPS. Lipoproteins are most abundant proteins that are expressed in all spirochetes and often determine how spirochetes interact with their environment. Lipoproteins are pro-inflammatory, may regulate responses from both innate and adaptive immunity and enable the spirochetes to adhere to the host or the tick midgut or to evade the immune system. However, most of the spirochetal lipoproteins have unknown function. Herein, the immunomodulatory effects of spirochetal lipoproteins are reviewed and are grouped into two main categories: effects related to immune evasion and effects related to immune activation. Understanding lipoprotein-induced immunomodulation will aid in elucidating innate immunopathogenesis processes and subsequent adaptive mechanisms potentially relevant to spirochetal disease vaccine development and to inflammatory events associated with spirochetal diseases.
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Affiliation(s)
- Theodoros Kelesidis
- Division of Infectious Diseases, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles , Los Angeles, CA , USA
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