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Sun S, Aguirre-Gamboa R, Barreiro LB. Transmission of stimulus-induced epigenetic changes through cell division is coupled to continuous transcription factor activity. Front Immunol 2023; 14:1129577. [PMID: 36999024 PMCID: PMC10043173 DOI: 10.3389/fimmu.2023.1129577] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 02/27/2023] [Indexed: 03/16/2023] Open
Abstract
Trained immunity, or innate immune memory, has been attributed to the long-term retention of stimulus-induced histone post-translational modifications (PTMs) following clearance of the initial stimulus. Yet, it remains unknown how this epigenetic memory can persist for months in dividing cells given the lack of any known mechanism for stimulus-induced histone PTMs to be directly copied from parent to daughter strand during DNA replication. Here, using time course RNA-seq, ChIP-seq, and infection assays, we find that trained macrophages are transcriptionally, epigenetically, and functionally re-programmed for at least 14 cell divisions after stimulus washout. However, the epigenetic changes observed after multiple rounds of cell division do not result from the self-sustained propagation of stimulus-induced epigenetic changes through cell division. Instead, long-lasting epigenetic differences between trained and non-trained cells are always coupled with changes in transcription factor (TF) activity, emphasizing the central role played by TFs, and gene expression changes more broadly, in driving the transmission of stimulus-induced epigenetic changes across cell divisions.
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Affiliation(s)
- Sarah Sun
- Committee on Immunology, University of Chicago, Chicago, IL, United States
- Medical Scientist Training Program, The University of Chicago, Chicago, IL, United States
| | - Raúl Aguirre-Gamboa
- Department of Human Genetics, University of Chicago, Chicago, IL, United States
- Section of Genetic Medicine, Department of Medicine, University of Chicago, Chicago, IL, United States
| | - Luis B. Barreiro
- Committee on Immunology, University of Chicago, Chicago, IL, United States
- Department of Human Genetics, University of Chicago, Chicago, IL, United States
- Section of Genetic Medicine, Department of Medicine, University of Chicago, Chicago, IL, United States
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2
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Gurjar D, Kumar Patra S, Bodhale N, Lenka N, Saha B. Leishmania intercepts IFN-γR signaling at multiple levels in macrophages. Cytokine 2022; 157:155956. [PMID: 35785668 DOI: 10.1016/j.cyto.2022.155956] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 06/13/2022] [Accepted: 06/24/2022] [Indexed: 11/26/2022]
Abstract
IFN-γ, a type 2 interferon and a cytokine, is critical for both innate and adaptive immunity. IFN-γ binds to the IFN-γRs on the cell membrane of macrophages, signals through JAK1-STAT-1 pathway and induces IFN-γ-stimulated genes (ISGs). As Leishmania amastigotes reside and replicate within macrophages, IFN-γ mediated macrophage activation eventuate in Leishmania elimination. As befits the principle of parasitism, the impaired IFN-γ responsiveness in macrophages ensures Leishmania survival. IFN-γ responsiveness is a function of integrated molecular events at multiple levels in the cells that express IFN-γ receptors. In Leishmania-infected macrophages, reduced IFN-γRα expression, impaired IFN-γRα and IFN-γRβ hetero-dimerization due to altered membrane lipid composition, reduced JAK-1 and STAT-1 phosphorylation but increased STAT-1 degradation and impaired ISGs induction collectively determine the IFN-γ responsiveness and the efficacy of IFN-γ induced antileishmanial function of macrophages. Therefore, parasite load is not only decided by the levels of IFN-γ produced but also by the IFN-γ responsiveness. Indeed, in Leishmania-infected patients, IFN-γ is produced but IFN-γ signalling is downregulated. However, the molecular mechanisms of IFN-γ responsiveness remain unclear. Therefore, we review the current understanding of IFN-γ responsiveness of Leishmania-infected macrophages.
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Affiliation(s)
- Dhiraj Gurjar
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| | | | - Neelam Bodhale
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| | - Nibedita Lenka
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
| | - Bhaskar Saha
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
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3
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Brar HK, Roy G, Kanojia A, Madan E, Madhubala R, Muthuswami R. Chromatin-Remodeling Factor BRG1 Is a Negative Modulator of L. donovani in IFNγ Stimulated and Infected THP-1 Cells. Front Cell Infect Microbiol 2022; 12:860058. [PMID: 35433496 PMCID: PMC9011159 DOI: 10.3389/fcimb.2022.860058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 03/14/2022] [Indexed: 11/13/2022] Open
Abstract
Intracellular pathogens manipulate the host cell for their own survival by contributing to modifications of host epigenome, and thus, altering expression of genes involved in the pathogenesis. Both ATP-dependent chromatin remodeling complex and histone modifications has been shown to be involved in the activation of IFNγ responsive genes. Leishmania donovani is an intracellular pathogen that causes visceral leishmaniasis. The strategies employed by Leishmania donovani to modulate the host epigenome in order to overcome the host defense for their persistence has been worked out in this study. We show that L. donovani negatively affects BRG1, a catalytic subunit of mammalian SWI/SNF chromatin remodeling complex, to alter IFNγ induced host responses. We observed that L. donovani infection downregulates BRG1 expression both at transcript and protein levels in cells stimulated with IFNγ. We also observed a significant decrease in IFNγ responsive gene, Class II transactivator (CIITA), as well as its downstream genes, MHC-II (HLA-DR and HLA-DM). Also, the occupancy of BRG1 at CIITA promoters I and IV was disrupted. A reversal in CIITA expression and decreased parasite load was observed with BRG1 overexpression, thus, suggesting BRG1 is a potential negative regulator for the survival of intracellular parasites in an early phase of infection. We also observed a decrease in H3 acetylation at the promoters of CIITA, post parasite infection. Silencing of HDAC1, resulted in increased CIITA expression, and further decreased parasite load. Taken together, we suggest that intracellular parasites in an early phase of infection negatively regulates BRG1 by using host HDAC1 for its survival inside the host.
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Affiliation(s)
- Harsimran Kaur Brar
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Gargi Roy
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Akanksha Kanojia
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Evanka Madan
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Rentala Madhubala
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- *Correspondence: Rentala Madhubala, ; Rohini Muthuswami,
| | - Rohini Muthuswami
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- *Correspondence: Rentala Madhubala, ; Rohini Muthuswami,
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4
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Oliveira LG, Souza-Testasicca MC, Ricotta TNQ, Vago JP, dos Santos LM, Crepaldi F, Lima KM, Queiroz-Junior C, Sousa LP, Fernandes AP. Temporary Shutdown of ERK1/2 Phosphorylation Is Associated With Activation of Adaptive Immune Cell Responses and Disease Progression During Leishmania amazonensis Infection in BALB/c Mice. Front Immunol 2022; 13:762080. [PMID: 35145518 PMCID: PMC8821891 DOI: 10.3389/fimmu.2022.762080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 01/04/2022] [Indexed: 11/22/2022] Open
Abstract
Leishmania spp. infection outcomes are dependent on both host and parasite factors. Manipulation of host signaling pathways involved in the generation of immune responses is thought to be one of the most common mechanisms used by parasites for persistence within the host. Considering the diversity of pathologies caused by different Leishmania spp., it is plausible that significant differences may exist in the mechanisms of host cell manipulation by each parasite species, which may have implications when developing new vaccine or treatment strategies. Here we show that in L. braziliensis-infection in BALB/c mice, a model of resistance, activation of ERK1/2 coincides with the peak of inflammatory responses and resolution of tissue parasitism. In contrast, in the susceptibility model of L. amazonensis-infection, an early silent phase of infection is observed, detected solely by quantification of parasite loads. At this early stage, only basal levels of P-ERK1/2 are observed. Later, after a brief shutdown of ERK1/2 phosphorylation, disease progression is observed and is associated with increased inflammation, lesion size and tissue parasitism. Moreover, the short-term down-regulation of ERK1/2 activation affected significantly downstream inflammatory pathways and adaptive T cell responses. Administration of U0126, a MEK/ERK inhibitor, confirmed this phenomenon, since bigger lesions and higher parasite loads were seen in infected mice that received U0126. To investigate how kinetics of ERK1/2 activation could affect the disease progression, U0126 was administered to L. amazonensis-infected animals earlier than the P-ERK1/2 switch off time-point. This intervention resulted in anticipation of the same effects on inflammatory responses and susceptibility phenotype seen in the natural course of infection. Additionally, in vitro inhibition of ERK1/2 affected the phagocytosis of L. amazonensis by BMDMs. Collectively, our findings reveal distinct temporal patterns of activation of inflammatory responses in L. braziliensis and L. amazonensis in the same animal background and a pivotal role for a brief and specific shutdown of ERK1/2 activation at late stages of L. amazonensis infection. Since activation of inflammatory responses is a crucial aspect for the control of infectious processes, these findings may be important for the search of new and specific strategies of vaccines and treatment for tegumentary leishmaniasis.
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Affiliation(s)
- Leandro G. Oliveira
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Tiago Nery Queiroga Ricotta
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Juliana P. Vago
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Liliane M. dos Santos
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Frederico Crepaldi
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Kátia M. Lima
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Celso Queiroz-Junior
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Lirlândia P. Sousa
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ana Paula Fernandes
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- *Correspondence: Ana Paula Fernandes,
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5
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Smirlis D, Dingli F, Pescher P, Prina E, Loew D, Rachidi N, Späth GF. SILAC-based quantitative proteomics reveals pleiotropic, phenotypic modulation in primary murine macrophages infected with the protozoan pathogen Leishmania donovani. J Proteomics 2019; 213:103617. [PMID: 31846769 DOI: 10.1016/j.jprot.2019.103617] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 12/04/2019] [Accepted: 12/13/2019] [Indexed: 01/06/2023]
Abstract
Leishmaniases are major vector-borne tropical diseases responsible for great human morbidity and mortality, caused by protozoan, trypanosomatid parasites of the genus Leishmania. In the mammalian host, parasites survive and multiply within mononuclear phagocytes, especially macrophages. However, the underlying mechanisms by which Leishmania spp. affect their host are not fully understood. Herein, proteomic alterations of primary, bone marrow-derived BALB/c macrophages are documented after 72 h of infection with Leishmania donovani insect-stage promastigotes, applying a SILAC-based, quantitative proteomics approach. The protocol was optimised by combining strong anion exchange and gel electrophoresis fractionation that displayed similar depth of analysis (combined total of 6189 mouse proteins). Our analyses revealed 86 differentially modulated proteins (35 showing increased and 51 decreased abundance) in response to Leishmania donovani infection. The proteomics results were validated by analysing the abundance of selected proteins. Intracellular Leishmania donovani infection led to changes in various host cell biological processes, including primary metabolism and catabolic process, with a significant enrichment in lysosomal organisation. Overall, our analysis establishes the first proteome of bona fide primary macrophages infected ex vivo with Leishmania donovani, revealing new mechanisms acting at the host/pathogen interface. SIGNIFICANCE: Little is known on proteome changes that occur in primary macrophages after Leishmania donovani infection. This study describes a SILAC-based quantitative proteomics approach to characterise changes of bone marrow-derived macrophages infected with L. donovani promastigotes for 72 h. With the application of SILAC and the use of SAX and GEL fractionation methods, we have tested new routes for proteome quantification of primary macrophages. The protocols developed here can be applicable to other diseases and pathologies. Moreover, this study sheds important new light on the "proteomic reprogramming" of infected macrophages in response to L. donovani promastigotes that affects primary metabolism, cellular catabolic processes, and lysosomal/vacuole organisation. Thus, our study reveals key molecules and processes that act at the host/pathogen interface that may inform on new immuno- or chemotherapeutic interventions to combat leishmaniasis.
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Affiliation(s)
- Despina Smirlis
- Institut Pasteur and Institut National de Santé et Recherche Médicale INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France; Hellenic Pasteur Institute, Molecular Parasitology Laboratory, Athens, Greece.
| | - Florent Dingli
- Laboratoire de Spectrométrie de Masse Protéomique, Centre de Recherche, Institut Curie, Université de recherche PSL, Paris, France
| | - Pascale Pescher
- Institut Pasteur and Institut National de Santé et Recherche Médicale INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Eric Prina
- Institut Pasteur and Institut National de Santé et Recherche Médicale INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Damarys Loew
- Laboratoire de Spectrométrie de Masse Protéomique, Centre de Recherche, Institut Curie, Université de recherche PSL, Paris, France
| | - Najma Rachidi
- Institut Pasteur and Institut National de Santé et Recherche Médicale INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Gerald F Späth
- Institut Pasteur and Institut National de Santé et Recherche Médicale INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France.
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6
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Nyambura LW, Jarmalavicius S, Walden P. Impact of Leishmania donovani infection on the HLA I self peptide repertoire of human macrophages. PLoS One 2018; 13:e0200297. [PMID: 30001391 PMCID: PMC6042751 DOI: 10.1371/journal.pone.0200297] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 06/23/2018] [Indexed: 02/07/2023] Open
Abstract
Macrophages are specialized antigen-presenting cells that process and present self-antigens for induction of tolerance, and foreign antigens to initiate T cell-mediated immunity. Despite this, Leishmania donovani (LD) are able to parasitize the macrophages and persist. The impact of this parasitizing and persistence on antigen processing and presentation by macrophages remains poorly defined. To gain insight into this, we analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and compared the HLA-I self-peptidomes, proteasome compositions, HLA expression and activation states of non-infected and LD-infected THP1-derived macrophages. We found that, though both HLA-I peptidomes were dominated by nonapeptides, they were heterogeneous and individualized, with differences in HLA binding affinities and anchor residues. Non-infected and LD-infected THP1-derived macrophages were able to sample peptides from source proteins of almost all subcellular locations and involved in various cellular functions, but in different proportions. In the infected macrophages, there was increased sampling of plasma membrane and extracellular proteins, and those involved in immune responses, cell communication/signal transduction and metabolism/energy pathways, and decreased sampling of nuclear and cytoplasmic proteins and those involved in protein metabolism, RNA binding and cell growth and/or maintenance. Though the activation state of infected macrophages was unchanged, their proteasome composition was altered.
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Affiliation(s)
- Lydon Wainaina Nyambura
- Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Dermatology, Venerology and Allergology, Clinical Research Group 'Tumor Immunology', Berlin, Germany
- Humboldt Universität zu Berlin, Lebenswissenschaftliche Fakultät, Institut für Biologie, Berlin, Germany
| | - Saulius Jarmalavicius
- Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Dermatology, Venerology and Allergology, Clinical Research Group 'Tumor Immunology', Berlin, Germany
| | - Peter Walden
- Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Dermatology, Venerology and Allergology, Clinical Research Group 'Tumor Immunology', Berlin, Germany
- * E-mail:
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7
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Soulat D, Bogdan C. Function of Macrophage and Parasite Phosphatases in Leishmaniasis. Front Immunol 2017; 8:1838. [PMID: 29312331 PMCID: PMC5743797 DOI: 10.3389/fimmu.2017.01838] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 12/05/2017] [Indexed: 01/23/2023] Open
Abstract
The kinetoplastid protozoan parasites belonging to the genus Leishmania are the causative agents of different clinical forms of leishmaniasis, a vector-borne infectious disease with worldwide prevalence. The protective host immune response against Leishmania parasites relies on myeloid cells such as dendritic cells and macrophages in which upon stimulation by cytokines (e.g., interferon-γ) a complex network of signaling pathways is switched on leading to strong antimicrobial activities directed against the intracellular parasite stage. The regulation of these pathways classically depends on post-translational modifications of proteins, with phosphorylation events playing a cardinal role. Leishmania parasites deactivate their phagocytic host cells by inducing specific mammalian phosphatases that are capable to impede signaling. On the other hand, there is now also evidence that Leishmania spp. themselves express phosphatases that might target host cell molecules and thereby facilitate the intracellular survival of the parasite. This review will present an overview on the modulation of host phosphatases by Leishmania parasites as well as on the known families of Leishmania phosphatases and their possible function as virulence factors. A more detailed understanding of the role of phosphatases in Leishmania–host cell interactions might open new avenues for the treatment of non-healing, progressive forms of leishmaniasis.
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Affiliation(s)
- Didier Soulat
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Interdisciplinary Center of the FAU, Erlangen, Germany
| | - Christian Bogdan
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Interdisciplinary Center of the FAU, Erlangen, Germany
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8
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Gomez CP, Descoteaux A. Moesin and myosin IIA modulate phagolysosomal biogenesis in macrophages. Biochem Biophys Res Commun 2017; 495:1964-1971. [PMID: 29247647 DOI: 10.1016/j.bbrc.2017.12.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 12/12/2017] [Indexed: 12/20/2022]
Abstract
Biogenesis of phagolysosomes is central to the elimination of pathogens by macrophages. We previously showed that Src homology region 2 domain-containing phosphatase 1 (SHP-1) participates in the regulation of phagosome maturation. Through proteomics, we identified moesin and the non-muscle myosin-IIA as proteins interacting with SHP-1 during phagocytosis. Silencing of either moesin or myosin IIA with small interfering RNA inhibited phagosomal acidification and recruitment of LAMP-1. Moreover, the intraphagosomal oxidative burst was impaired in the absence of either SHP-1 or myosin IIA but not moesin. Finally, absence of either SHP-1, moesin, or myosin IIA ablated the capacity of macrophages to clear bacterial infection. Collectively, these results implicate both moesin and myosin IIA in the regulation of phagolysosome biogenesis and in host defense against infections.
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Affiliation(s)
- Carolina P Gomez
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, QC, H7V 1B7, Canada
| | - Albert Descoteaux
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, QC, H7V 1B7, Canada.
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9
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Alteration of SHP-1/p-STAT3 Signaling: A Potential Target for Anticancer Therapy. Int J Mol Sci 2017; 18:ijms18061234. [PMID: 28594363 PMCID: PMC5486057 DOI: 10.3390/ijms18061234] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/01/2017] [Accepted: 06/05/2017] [Indexed: 12/12/2022] Open
Abstract
The Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 1 (SHP-1), a non-receptor protein tyrosine phosphatase, has been reported as a negative regulator of phosphorylated signal transducer and activator of transcription 3 (STAT3) and linked to tumor development. In this present review, we will discuss the importance and function of SHP-1/p-STAT3 signaling in nonmalignant conditions as well as malignancies, its cross-talk with other pathways, the current clinical development and the potential role of inhibitors of this pathway in anticancer therapy and clinical relevance of SHP-1/p-STAT3 in cancers. Lastly, we will summarize and highlight work involving novel drugs/compounds targeting SHP-1/p-STAT3 signaling and combined strategies that were/are discovered in our and our colleagues’ laboratories.
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10
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Roy S, Mandal C. Leishmania donovani Utilize Sialic Acids for Binding and Phagocytosis in the Macrophages through Selective Utilization of Siglecs and Impair the Innate Immune Arm. PLoS Negl Trop Dis 2016; 10:e0004904. [PMID: 27494323 PMCID: PMC4975436 DOI: 10.1371/journal.pntd.0004904] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 07/14/2016] [Indexed: 12/15/2022] Open
Abstract
Background Leishmania donovani, belonging to a unicellular protozoan parasite, display the differential level of linkage-specific sialic acids on their surface. Sialic acids binding immunoglobulin-like lectins (siglecs) are a class of membrane-bound receptors present in the haematopoetic cell lineages interact with the linkage-specific sialic acids. Here we aimed to explore the utilization of sialic acids by Leishmania donovani for siglec-mediated binding, phagocytosis, modulation of innate immune response and signaling pathways for establishment of successful infection in the host. Methodology/Principle Findings We have found enhanced binding of high sialic acids containing virulent strains (AG83+Sias) with siglec-1 and siglec-5 present on macrophages compared to sialidase treated AG83+Sias (AG83-Sias) and low sialic acids-containing avirulent strain (UR6) by flow cytometry. This specific receptor-ligand interaction between sialic acids and siglecs were further confirmed by confocal microscopy. Sialic acids-siglec-1-mediated interaction of AG83+Sias with macrophages induced enhanced phagocytosis. Additionally, sialic acids-siglec-5 interaction demonstrated reduced ROS, NO generation and Th2 dominant cytokine response upon infection with AG83+Sias in contrast to AG83-Sias and UR6. Sialic acids-siglecs binding also facilitated multiplication of intracellular amastigotes. Moreover, AG83+Sias induced sialic acids-siglec-5-mediated upregulation of host phosphatase SHP-1. Such sialic acids-siglec interaction was responsible for further downregulation of MAPKs (p38, ERK and JNK) and PI3K/Akt pathways followed by the reduced translocation of p65 subunit of NF-κβ to the nucleus from cytosol in the downstream signaling pathways. This sequence of events was reversed in AG83-Sias and UR6-infected macrophages. Besides, siglec-knockdown macrophages also showed the reversal of AG83+Sias infection-induced effector functions and downstream signaling events. Conclusions/Significances Taken together, this study demonstrated that virulent parasite (AG83+Sias) establish a unique sialic acids-mediated binding and subsequent phagocytosis in the host cell through the selective exploitation of siglec-1. Additionally, sialic acids-siglec-5 interaction altered the downstream signaling pathways which contributed impairment of immune effector functions of macrophages. To the best of our knowledge, this is a comprehensive report describing sialic acids-siglec interactions and their role in facilitating uptake of the virulent parasite within the host. Sialic acids are nine carbon sugars present on terminal cell surface glycoproteins and glycolipids. Siglec is a membrane receptor that belongs to an immunoglobulin super family present in almost all the haematopoetic cell lineages. There are 14 different types of siglecs present on human immune cells that take an active part in balancing the magnitude of immunological reactions. In general, these siglecs bind with sialic acids and negatively regulate the immune response. Leishmania contains sialic acids on its surface. Virulent parasites utilize this sugar to bind with macrophages through siglec-1 and siglec-5 compared to low sialic acids containing avirulent parasites. Such sialic acids-siglec-mediated interactions exhibited a suppressed host immune response which helped them to establish successful infection compared to desialylated virulent and avirulent parasites, as well as, siglec-depleted macrophages. Interestingly, interaction between sialic acids and siglec-1 induced enhanced phagocytosis, while sialic acids-siglec-5 interaction upregulated the phosphatase SHP-1. This interaction with the virulent strain exhibited deactivation of various downstream signaling pathways and ultimately controlled translocation of a functional component of transcription factor NF-κβ for regulation of cytokines and other effector molecules in infected macrophages. Thus, the interaction between the parasite and the host cells through sialic acids-siglec binding is clearly a newly identified mechanism by which parasites can establish successful infection by subverting the host’s innate immune response.
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Affiliation(s)
- Saptarshi Roy
- Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Chitra Mandal
- Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- * E-mail:
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11
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Atayde VD, Hassani K, da Silva Lira Filho A, Borges AR, Adhikari A, Martel C, Olivier M. Leishmania exosomes and other virulence factors: Impact on innate immune response and macrophage functions. Cell Immunol 2016; 309:7-18. [PMID: 27499212 DOI: 10.1016/j.cellimm.2016.07.013] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/14/2016] [Accepted: 07/25/2016] [Indexed: 12/23/2022]
Abstract
Leishmania parasites are the causative agents of the leishmaniases, a collection of vector-borne diseases that range from simple cutaneous to fatal visceral forms. Employing potent immune modulation mechanisms, Leishmania is able to render the host macrophage inactive and persist inside its phagolysosome. In the last few years, the role of exosomes in Leishmania-host interactions has been increasingly investigated. For instance, it was reported that Leishmania exosome release is augmented following temperature shift, a condition mimicking parasite's entry into its mammalian host. Leishmania exosomes were found to strongly affect macrophage cell signaling and functions, similarly to whole parasites. Importantly, these vesicles were shown to be pro-inflammatory, capable to recruit neutrophils at their inoculation site exacerbating the pathology. In this review, we provide the most recent insights on the role of exosomes and other virulence factors, especially the surface protease GP63, in Leishmania-host interactions, deepening our knowledge on leishmaniasis and paving the way for the development of new therapeutics.
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Affiliation(s)
- Vanessa Diniz Atayde
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Kasra Hassani
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Alonso da Silva Lira Filho
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Andrezza Raposo Borges
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Anupam Adhikari
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Caroline Martel
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Martin Olivier
- Departments of Medicine, Microbiology and Immunology, McGill University, 3775 University Street, Montréal, QC H3A 2B4, Canada; Infectious Diseases and Immunity in Global Heath Program, The Research Institute of the McGill University Health Centre, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada.
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Dual Transcriptome Profiling of Leishmania-Infected Human Macrophages Reveals Distinct Reprogramming Signatures. mBio 2016; 7:mBio.00027-16. [PMID: 27165796 PMCID: PMC4959658 DOI: 10.1128/mbio.00027-16] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Macrophages are mononuclear phagocytes that constitute a first line of defense against pathogens. While lethal to many microbes, they are the primary host cells of Leishmania spp. parasites, the obligate intracellular pathogens that cause leishmaniasis. We conducted transcriptomic profiling of two Leishmania species and the human macrophage over the course of intracellular infection by using high-throughput RNA sequencing to characterize the global gene expression changes and reprogramming events that underlie the interactions between the pathogen and its host. A systematic exclusion of the generic effects of large-particle phagocytosis revealed a vigorous, parasite-specific response of the human macrophage early in the infection that was greatly tempered at later time points. An analogous temporal expression pattern was observed with the parasite, suggesting that much of the reprogramming that occurs as parasites transform into intracellular forms generally stabilizes shortly after entry. Following that, the parasite establishes an intracellular niche within macrophages, with minimal communication between the parasite and the host cell later during the infection. No significant difference was observed between parasite species transcriptomes or in the transcriptional response of macrophages infected with each species. Our comparative analysis of gene expression changes that occur as mouse and human macrophages are infected by Leishmania spp. points toward a general signature of the Leishmania-macrophage infectome. Little is known about the transcriptional changes that occur within mammalian cells harboring intracellular pathogens. This study characterizes the gene expression signatures of Leishmania spp. parasites and the coordinated response of infected human macrophages as the pathogen enters and persists within them. After accounting for the generic effects of large-particle phagocytosis, we observed a parasite-specific response of the human macrophages early in infection that was reduced at later time points. A similar expression pattern was observed in the parasites. Our analyses provide specific insights into the interplay between human macrophages and Leishmania parasites and constitute an important general resource for the study of how pathogens evade host defenses and modulate the functions of the cell to survive intracellularly.
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13
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Abstract
The ability of Leishmania parasites to infect and persist in the antigen-presenting cell population of their mammalian hosts is dependent on their ability to gain entry to their host and host cells, to survive the mammalian cell environment, and to suppress or evade the protective immune response mechanisms of their hosts. A multitude of genes and their products have been implicated in each of these virulence-enhancing strategies to date, and we present an overview of the nature and known function of such virulence genes.
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Isnard A, Christian JG, Kodiha M, Stochaj U, McMaster WR, Olivier M. Impact of Leishmania infection on host macrophage nuclear physiology and nucleopore complex integrity. PLoS Pathog 2015; 11:e1004776. [PMID: 25826301 PMCID: PMC4380401 DOI: 10.1371/journal.ppat.1004776] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 03/03/2015] [Indexed: 12/23/2022] Open
Abstract
The protease GP63 is an important virulence factor of Leishmania parasites. We previously showed that GP63 reaches the perinuclear area of host macrophages and that it directly modifies nuclear translocation of the transcription factors NF-κB and AP-1. Here we describe for the first time, using molecular biology and in-depth proteomic analyses, that GP63 alters the host macrophage nuclear envelope, and impacts on nuclear processes. Our results suggest that GP63 does not appear to use a classical nuclear localization signal common between Leishmania species for import, but degrades nucleoporins, and is responsible for nuclear transport alterations. In the nucleoplasm, GP63 activity accounts for the degradation and mislocalization of proteins involved amongst others in gene expression and in translation. Collectively, our data indicates that Leishmania infection strongly affects nuclear physiology, suggesting that targeting of nuclear physiology may be a strategy beneficial for virulent Leishmania parasites. Unicellular parasites of the genus Leishmania are the causative agent of leishmaniasis, a disease affecting 12 million people worldwide, mainly in tropical and subtropical regions of the developing world. They have evolved strategies to circumvent cellular defense mechanisms favouring their survival. This includes the cleavage and activation of proteins and the subsequent block of signals within the host cells. In this study we discovered that a Leishmania virulence factor, GP63, is able to reach host cell nuclei and affect protein transport from and into the nucleus. Through the analysis of the protein content of nuclei after parasite infection we revealed that Leishmania, predominantly through the protein cleaving enzyme GP63, can alter several processes within the nucleus, amongst others mechanisms associated with gene expression and nucleic acid metabolism. Thus, we here introduce a novel strategy of how Leishmania parasites may overcome host cell defense and ensure their own survival.
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Affiliation(s)
- Amandine Isnard
- Departments of Medicine and Microbiology & Immunology, The Research Institute of the McGill University Health Centre, McGill University, Montréal, Quebec, Canada
| | - Jan G. Christian
- Departments of Medicine and Microbiology & Immunology, The Research Institute of the McGill University Health Centre, McGill University, Montréal, Quebec, Canada
| | - Mohamed Kodiha
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - Ursula Stochaj
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - W. Robert McMaster
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Martin Olivier
- Departments of Medicine and Microbiology & Immunology, The Research Institute of the McGill University Health Centre, McGill University, Montréal, Quebec, Canada
- * E-mail:
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15
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Proteomic-based approach to gain insight into reprogramming of THP-1 cells exposed to Leishmania donovani over an early temporal window. Infect Immun 2015; 83:1853-68. [PMID: 25690103 DOI: 10.1128/iai.02833-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/13/2015] [Indexed: 12/20/2022] Open
Abstract
Leishmania donovani, a protozoan parasite, is the causative agent of visceral leishmaniasis. It lives and multiplies within the harsh environment of macrophages. In order to investigate how intracellular parasite manipulate the host cell environment, we undertook a quantitative proteomic study of human monocyte-derived macrophages (THP-1) following infection with L. donovani. We used the isobaric tags for relative and absolute quantification (iTRAQ) method and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to compare expression profiles of noninfected and L. donovani-infected THP-1 cells. We detected modifications of protein expression in key metabolic pathways, including glycolysis and fatty acid oxidation, suggesting a global reprogramming of cell metabolism by the parasite. An increased abundance of proteins involved in gene transcription, RNA splicing (heterogeneous nuclear ribonucleoproteins [hnRNPs]), histones, and DNA repair and replication was observed at 24 h postinfection. Proteins involved in cell survival and signal transduction were more abundant at 24 h postinfection. Several of the differentially expressed proteins had not been previously implicated in response to the parasite, while the others support the previously identified proteins. Selected proteomics results were validated by real-time PCR and immunoblot analyses. Similar changes were observed in L. donovani-infected human monocyte-derived primary macrophages. The effect of RNA interference (RNAi)-mediated gene knockdown of proteins validated the relevance of the host quantitative proteomic screen. Our findings indicate that the host cell proteome is modulated after L. donovani infection, provide evidence for global reprogramming of cell metabolism, and demonstrate the complex relations between the host and parasite at the molecular level.
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Cecílio P, Pérez-Cabezas B, Santarém N, Maciel J, Rodrigues V, Cordeiro da Silva A. Deception and manipulation: the arms of leishmania, a successful parasite. Front Immunol 2014; 5:480. [PMID: 25368612 PMCID: PMC4202772 DOI: 10.3389/fimmu.2014.00480] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/19/2014] [Indexed: 12/12/2022] Open
Abstract
Leishmania spp. are intracellular parasitic protozoa responsible for a group of neglected tropical diseases, endemic in 98 countries around the world, called leishmaniasis. These parasites have a complex digenetic life cycle requiring a susceptible vertebrate host and a permissive insect vector, which allow their transmission. The clinical manifestations associated with leishmaniasis depend on complex interactions between the parasite and the host immune system. Consequently, leishmaniasis can be manifested as a self-healing cutaneous affliction or a visceral pathology, being the last one fatal in 85–90% of untreated cases. As a result of a long host–parasite co-evolutionary process, Leishmania spp. developed different immunomodulatory strategies that are essential for the establishment of infection. Only through deception and manipulation of the immune system, Leishmania spp. can complete its life cycle and survive. The understanding of the mechanisms associated with immune evasion and disease progression is essential for the development of novel therapies and vaccine approaches. Here, we revise how the parasite manipulates cell death and immune responses to survive and thrive in the shadow of the immune system.
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Affiliation(s)
- Pedro Cecílio
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Begoña Pérez-Cabezas
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Nuno Santarém
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Joana Maciel
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Vasco Rodrigues
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Anabela Cordeiro da Silva
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal ; Department of Biological Sciences, Faculty of Pharmacy, University of Porto , Porto , Portugal
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17
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Contreras I, Estrada JA, Guak H, Martel C, Borjian A, Ralph B, Shio MT, Fournier S, Krawczyk CM, Olivier M. Impact of Leishmania mexicana infection on dendritic cell signaling and functions. PLoS Negl Trop Dis 2014; 8:e3202. [PMID: 25255446 PMCID: PMC4177750 DOI: 10.1371/journal.pntd.0003202] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 08/19/2014] [Indexed: 12/02/2022] Open
Abstract
Leishmania parasites have the ability to modify macrophage signaling pathways in order to survive and multiply within its mammalian host. They are also known to invade other cells including neutrophils, fibroblasts and dendritic cells (DCs). DCs have an important role in immunity as the link between innate and adaptive immunity, necessary for the development of an effective response; however, the impact of Leishmania mexicana infection on DCs has been poorly studied. Herein, we report that Leishmania infection rapidly induced DC protein tyrosine phosphatases activity, leading to MAP kinases inactivation. In line with this, L. mexicana was found to decrease the nuclear translocation of transcription factors such as AP-1 and NF-κB. Concomitantly, L. mexicana-infected DCs showed reduced expression of several surface antigen-presenting and co-stimulatory molecules upon LPS stimulation. Leishmania-induced interference on DC maturation was further reflected by their reduced capacity to present OVA antigen to OVA-specific T cells, as shown by abrogation of IL-2 production by the T cells. Collectively, our data revealed that DC infection by L. mexicana appears to affect the cellular and immunological mechanisms necessary for the development of an effective and protective immune response, therefore favouring the survival and propagation of the parasite within its host. Parasites of the Leishmania genus have developed many strategies to survive inside their host. Initially, they were only considered capable of infecting macrophages; however, it has been observed that Leishmania is able to infect other cell types, such as fibroblast, neutrophils and dendritic cells (DCs). DCs are well known for their antigen-presentation capabilities, and they are considered as the fundamental bridge between the innate and adaptive immune responses. In this study, we attempted to elucidate the effect of L. mexicana promastigotes on DCs. Our results showed that L. mexicana inactivates signaling cascades responsible for the expression of immune effector molecules, such as cytokines, concomitantly with the activation of protein phosphatases in the host. Furthermore, we observed that promastigote-infected cells had lower expression of MHC and co-stimulatory molecules on their surface, as well as decreased antigen-presentation capacity. In conclusion, our study showed that Leishmania parasites are able to inactivate the immunological mechanisms of DCs, as they do in macrophages, in order to survive inside its host.
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Affiliation(s)
- Irazú Contreras
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
- Neurochemistry Laboratory, Faculty of Medicine. Universidad Autónoma del Estado de México, Toluca, Estado de México, México
| | - José A. Estrada
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
- Neurochemistry Laboratory, Faculty of Medicine. Universidad Autónoma del Estado de México, Toluca, Estado de México, México
| | - Hannah Guak
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Caroline Martel
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Alborz Borjian
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Benjamin Ralph
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Marina T. Shio
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Sylvie Fournier
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Connie M. Krawczyk
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
| | - Martin Olivier
- Department of Microbiology and Immunology, McGill University, Montréal, Quebec, Canada
- McGill TB International Centre and the Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
- * E-mail:
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18
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Ricardo-Carter C, Favila M, Polando RE, Cotton RN, Bogard Horner K, Condon D, Ballhorn W, Whitcomb JP, Yadav M, Geister RL, Schorey JS, McDowell MA. Leishmania major inhibits IL-12 in macrophages by signalling through CR3 (CD11b/CD18) and down-regulation of ETS-mediated transcription. Parasite Immunol 2014; 35:409-20. [PMID: 23834512 DOI: 10.1111/pim.12049] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/03/2013] [Indexed: 01/17/2023]
Abstract
Leishmania major is an aetiological agent of cutaneous leishmaniasis. The parasite primarily infects immune sentinel cells, specifically macrophages and dendritic cells, in the mammalian host. Infection is receptor mediated and is known to involve parasite binding to cell surface protein complement receptor 3 (CR3, Mac-1, CD11b/CD18). Engagement of CR3 by various ligands inhibits production of interleukin-12 (IL-12), the cytokine that drives antileishmanial T helper 1-type immune responses. Likewise, L. major infection inhibits IL-12 production and activation of host macrophages. Our data indicate that in the absence of CR3, L. major-infected bone marrow-derived macrophages produce more IL-12 and nitric oxide compared with WT cells upon lipopolysaccharide (LPS) stimulation. We therefore investigated multiple signalling pathways by which L. major may inhibit IL-12 transcription through CR3 ligation. We demonstrate that L. major infection does not elicit significant NFκB p65, MAPK, IRF-1 or IRF-8 activation in WT or CD11b-deficient macrophages. Furthermore, infection neither inhibits LPS-induced MAPK or NFκB activation nor blocks IFN-γ-activated IRF-1 and IRF-8. ETS-mediated transcription, however, is inhibited by L. major infection independently of CR3. Our data indicate that L. major-mediated inhibition of IL-12 occurs through CR3 engagement; however, the mechanism of inhibition is independent of NFκB, MAPK, IRF and ETS.
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Affiliation(s)
- C Ricardo-Carter
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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Gómez CP, Tiemi Shio M, Duplay P, Olivier M, Descoteaux A. The protein tyrosine phosphatase SHP-1 regulates phagolysosome biogenesis. THE JOURNAL OF IMMUNOLOGY 2012; 189:2203-10. [PMID: 22826316 DOI: 10.4049/jimmunol.1103021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The process of phagocytosis and phagosome maturation involves the recruitment of effector proteins that participate in phagosome formation and in the acidification and/or fusion with various endocytic vesicles. In the current study, we investigated the role of the Src homology region 2 domain-containing phosphatase 1 (SHP-1) in phagolysosome biogenesis. To this end, we used immortalized bone marrow macrophages derived from SHP-1-deficient motheaten mice and their wild-type littermates. We found that SHP-1 is recruited early and remains present on phagosomes for up to 4 h postphagocytosis. Using confocal immunofluorescence microscopy and Western blot analyses on purified phagosome extracts, we observed an impaired recruitment of lysosomal-associated membrane protein 1 in SHP-1-deficient macrophages. Moreover, Western blot analyses revealed that whereas the 51-kDa procathepsin D is recruited to phagosomes, it is not processed into the 46-kDa cathepsin D in the absence of SHP-1, suggesting a defect in acidification. Using the lysosomotropic agent LysoTracker as an indicator of phagosomal pH, we obtained evidence that in the absence of SHP-1, phagosome acidification was impaired. Taken together, these results are consistent with a role for SHP-1 in the regulation of signaling or membrane fusion events involved in phagolysosome biogenesis.
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Affiliation(s)
- Carolina P Gómez
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec H7V 1B7, Canada
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20
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Isnard A, Shio MT, Olivier M. Impact of Leishmania metalloprotease GP63 on macrophage signaling. Front Cell Infect Microbiol 2012; 2:72. [PMID: 22919663 PMCID: PMC3417651 DOI: 10.3389/fcimb.2012.00072] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Accepted: 05/03/2012] [Indexed: 11/18/2022] Open
Abstract
The intramacrophage protozoan parasites of Leishmania genus have developed sophisticated ways to subvert the innate immune response permitting their infection and propagation within the macrophages of the mammalian host. Several Leishmania virulence factors have been identified and found to be of importance for the development of leishmaniasis. However, recent findings are now further reinforcing the critical role played by the zinc-metalloprotease GP63 as a virulence factor that greatly influence host cell signaling mechanisms and related functions. GP63 has been found to be involved not only in the cleavage and degradation of various kinases and transcription factors, but also to be the major molecule modulating host negative regulatory mechanisms involving for instance protein tyrosine phosphatases (PTPs). Those latter being well recognized for their pivotal role in the regulation of a great number of signaling pathways. In this review article, we are providing a complete overview about the role of Leishmania GP63 in the mechanisms underlying the subversion of macrophage signaling and functions.
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Affiliation(s)
- Amandine Isnard
- Faculty of Medicine, Department of Medicine, Microbiology, and Immunology, The Research Institute of the McGill University Health Centre, McGill University Montréal, QC, Canada
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21
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Lambertz U, Silverman JM, Nandan D, McMaster WR, Clos J, Foster LJ, Reiner NE. Secreted virulence factors and immune evasion in visceral leishmaniasis. J Leukoc Biol 2012; 91:887-99. [PMID: 22442494 DOI: 10.1189/jlb.0611326] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Evasion or subversion of host immune responses is a well-established paradigm in infection with visceralizing leishmania. In this review, we summarize current findings supporting a model in which leishmania target host regulatory molecules and pathways, such as the PTP SHP-1 and the PI3K/Akt signaling cascade, to prevent effective macrophage activation. Furthermore, we describe how virulence factors, secreted by leishmania, interfere with macrophage intracellular signaling. Finally, we discuss mechanisms of secretion and provide evidence that leishmania use a remarkably adept, exosome-based secretion mechanism to export and deliver effector molecules to host cells. In addition to representing a novel mechanism for trafficking of virulence factors across membranes, recent findings indicate that leishmania exosomes may have potential as vaccine candidates.
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Affiliation(s)
- Ulrike Lambertz
- Department of Medicine Division of Infectious Diseases and the Experimental Medicine Program, University of British Columbia, Vancouver, Canada
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22
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Silverman JM, Reiner NE. Leishmania exosomes deliver preemptive strikes to create an environment permissive for early infection. Front Cell Infect Microbiol 2012; 1:26. [PMID: 22919591 PMCID: PMC3417360 DOI: 10.3389/fcimb.2011.00026] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 12/23/2011] [Indexed: 01/20/2023] Open
Abstract
Herein, we review evidence supporting a role for Leishmania exosomes during early infection. We suggest a model in which Leishmania secreted microvesicles released into the extracellular milieu deliver effector cargo to host target cells. This cargo mediates immunosuppression and functionally primes host cells for Leishmania invasion. Leishmania ssp. release microvesicles and the amount of vesicle release and the specific protein cargo of the vesicles is sensitive to changes in environmental conditions that mimic infection. Leishmania exosomes influence the phenotype of treated immune cells. For example, wild-type (WT) exosomes attenuate interferon-γ-induced pro-inflammatory cytokine production (TNF-α) by Leishmania-infected monocytes while conversely enhancing production of the anti-inflammatory cytokine IL-10. The Leishmania proteins GP63 and elongation factor-1α (EF-1α) are found in secreted vesicles and are likely important effectors responsible for these changes in phenotype. GP63 and EF-1α access host cell cytosol and activate multiple host protein-tyrosine phosphatases (PTPs). Activation of these PTPs negatively regulates interferon-γ signaling and this prevents effective expression of the macrophage microbicidal arsenal, including TNF-α and nitric oxide. In addition to changing macrophage phenotype, WT vesicles dampen the immune response of monocyte-derived dendritic cells and CD4+ T lymphocytes. This capacity is lost when the protein cargo of the vesicles is modified, specifically when the amount of GP63 and EF-1α in the vesicles is reduced. It appears that exosome delivery of effector proteins results in activation of host PTPs and the negative regulatory effects of the latter creates a pro-parasitic environment. The data suggest that Leishmania exosomes secreted upon initial infection are capable of delivering effector cargo to naïve target cells wherein the cargo primes host cells for infection by interfering with host cell signaling pathways.
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Affiliation(s)
- Judith Maxwell Silverman
- Brain Research Center, Division of Neurology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
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Host cell signalling and leishmania mechanisms of evasion. J Trop Med 2011; 2012:819512. [PMID: 22131998 PMCID: PMC3216306 DOI: 10.1155/2012/819512] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/16/2011] [Indexed: 12/18/2022] Open
Abstract
Leishmania parasites are able to secure their survival and propagation within their host by altering signalling pathways involved in the ability of macrophages to kill pathogens or to engage adaptive immune system. An important step in this immune evasion process is the activation of host protein tyrosine phosphatase SHP-1 by Leishmania. SHP-1 has been shown to directly inactivate JAK2 and Erk1/2 and to play a role in the negative regulation of several transcription factors involved in macrophage activation. These signalling alterations contribute to the inactivation of critical macrophage functions (e.g., Nitric oxide, IL-12, and TNF-α). Additionally, to interfere with IFN-γ receptor signalling, Leishmania also alters several LPS-mediated responses. Recent findings from our laboratory revealed a pivotal role for SHP-1 in the inhibition of TLR-induced macrophage activation through binding to and inactivating IL-1-receptor-associated kinase 1 (IRAK-1). Furthermore, we identified the binding site as an evolutionarily conserved ITIM-like motif, which we named kinase tyrosine-based inhibitory motif (KTIM). Collectively, a better understanding of the evasion mechanisms utilized by Leishmania parasite could help to develop more efficient antileishmanial therapies in the near future.
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TGF-β1 re-programs TLR4 signaling in L. donovani infection: enhancement of SHP-1 and ubiquitin-editing enzyme A20. Immunol Cell Biol 2011; 90:640-54. [PMID: 21968712 DOI: 10.1038/icb.2011.80] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Visceral leishmaniasis (VL), caused by Leishmania donovani, is a major health concern in India. It represents T-helper type 2 (Th2) bias of cytokines in active state and Th1 bias at cure. However, the role of the parasite in regulating Toll-like receptor (TLR)-mediated macrophage activation in VL patients remains elusive. In this report, we demonstrated that later stages of L. donovani infection rendered tolerance to macrophages, leading to incapability for the production of inflammatory cytokines like tumor necrosis factor (TNF)-α and interleukin (IL)-1β in response to TLR stimulation. Overexpression of transforming growth factor (TGF)-β(1), but not IL-10, resulted in suppressed lipopolysaccharide (LPS)-induced production of TNF-α and downregulation of TLR4 expression in L. donovani-infected macrophages. Recombinant human (rh)TGF-β(1) markedly enhanced tyrosine phosphatase (Src homology region 2 domain-containing phosphatase-1) activity, but inhibited IL-1 receptor-activated kinase (IRAK)-1 activation. Addition of neutralizing TGF-β(1) antibody reversed these effects, and thus suggesting the pivotal role of TGF-β(1) in promoting refractoriness for LPS in macrophages. Surprisingly, the use of a tyrosine phosphatase inhibitor (sodium orthovanadate, Na(3)VO(4)) promoted IRAK-1 activation, confirming the negative inhibitory role of tyrosine phosphatase in macrophage activation. Furthermore, rhTGF-β(1) induced tolerance in infected macrophages by reducing inhibitory protein (IκBα) degradation in a time-dependent manner. In addition, short interfering RNA studies proved that overexpression of A20 ubiquitin-editing protein complex induced inhibitory activity of TGF-β(1) on LPS-mediated nuclear factor-κB activation. Thus, these findings suggest that TGF-β(1) promotes overexpression of A20 through tyrosine phosphatase activity that ensures transient activation of inflammatory signaling pathways in macrophages in active L. donovani infection.
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Abstract
Leishmania is a genus of protozoan parasites that are transmitted by the bite of phlebotomine sandflies and give rise to a range of diseases (collectively known as leishmaniases) that affect over 150 million people worldwide. Cellular immune mechanisms have a major role in the control of infections with all Leishmania spp. However, as discussed in this Review, recent evidence suggests that each host-pathogen combination evokes different solutions to the problems of parasite establishment, survival and persistence. Understanding the extent of this diversity will be increasingly important in ensuring the development of broadly applicable vaccines, drugs and immunotherapeutic interventions.
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TGF-β-regulated tyrosine phosphatases induce lymphocyte apoptosis in Leishmania donovani-infected hamsters. Immunol Cell Biol 2010; 89:466-74. [PMID: 20856262 DOI: 10.1038/icb.2010.108] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Visceral leishmaniasis, which is caused by Leishmania donovani, is one of the major health problems of the Indian subcontinent. Infected hosts have been reported to have impaired lymphoproliferation. However, the fate of anergic cells is still elusive. In the present investigation, L. donovani-infected hamsters were used to study the mechanism of lymphocyte cell death. Lymph node-derived lymphocytes were analysed for apoptotic death through mitochondrial abnormality, caspase activity and DNA degradation. The data demonstrate that the disease progression leads to a gradual impairment of lymphocyte proliferation in the presence of Concanavalin A. The fate of the anergic lymphocytes is intrinsic apoptosis, which is evident by the depolarization of the mitochondrial membrane potential, cytosolic release of cytochrome c, caspase activation and DNA fragmentation. Tumour growth factor (TGF)-β, which is secreted by macrophages, was significantly upregulated in the lymph node compartment of infected hamsters. Adding a neutralizing TGF-β antibody and a recombinant TGF-β resulted in the downregulation and induction of lymphocyte apoptosis, respectively. Furthermore, it has been observed that TGF-β triggers the apoptotic death of lymphocytes through the upregulation of tyrosine phosphatase activity and that the use of sodium orthovanadate (Na(3)VO(4), a tyrosine phosphatase inhibitor) reduces the apoptotic frequency. Thus, this study clearly reports the novel involvement of tyrosine phosphatases in TGF-β-induced lymphocyte apoptosis in Leishmania-infected hamsters.
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Leishmania interferes with host cell signaling to devise a survival strategy. J Biomed Biotechnol 2010; 2010:109189. [PMID: 20396387 PMCID: PMC2852600 DOI: 10.1155/2010/109189] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 10/21/2009] [Accepted: 01/28/2010] [Indexed: 01/24/2023] Open
Abstract
The protozoan parasite Leishmania spp. exists as extracellular promastigotes in its vector whereas it resides and replicates as amastigotes within the macrophages of its mammalian host. As a survival strategy, Leishmania modulates macrophage functions directly or indirectly. The direct interference includes prevention of oxidative burst and the effector functions that lead to its elimination. The indirect effects include the antigen presentation and modulation of T cell functions in such a way that the effector T cells help the parasite survive by macrophage deactivation. Most of these direct and indirect effects are regulated by host cell receptor signaling that occurs through cycles of phosphorylation and dephosphorylation in cascades of kinases and phosphatases. This review highlights how Leishmania selectively manipulates the different signaling pathways to ensure its survival.
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Comparative study of the ability of Leishmania mexicana promastigotes and amastigotes to alter macrophage signaling and functions. Infect Immun 2010; 78:2438-45. [PMID: 20368344 DOI: 10.1128/iai.00812-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Leishmania alternates between two morphologically different stages, promastigotes and amastigotes. While the majority of reports focused on how the promastigote form can alter macrophage (Mphi) signaling and function, fewer reports investigated signaling alterations mediated by amastigotes, and there is a lack of comparative studies. In this study, we performed a comparison between the ability of both forms of the parasite to alter Mphi signaling and functions. Here, we show that both promastigotes and amastigotes were able to rapidly activate host protein tyrosine phosphatases (PTPs), importantly the Src homology 2 domain-containing PTP (SHP-1). However, we found that PTP-1B is specifically activated by promastigote but not amastigote infection and that lmcpb(-/-) promastigotes were no longer able to activate PTP-1B. We also show a similarity in the way promastigotes and amastigotes inactivate the transcription factors (TFs) STAT-1alpha and AP-1, but we show differences in the modulation of NF-kappaB, with promastigotes cleaving the p65 subunit, generating a smaller p35 subunit, and amastigotes fully degrading the p65 subunit with no p35 production. Importantly, we show that the cysteine proteinase LmCPb plays a key role in the alteration of NF-kappaB, STAT-1alpha, and AP-1 by promastigote and amastigote infections, ultimately leading to the inability of these TFs to translocate to the nucleus in response to gamma interferon (IFN-gamma) stimulation and thus contributing to the ability of both parasite forms to effectively block IFN-gamma-mediated nitric oxide (NO) production in Mphis.
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Calegari-Silva TC, Pereira RM, De-Melo LDB, Saraiva EM, Soares DC, Bellio M, Lopes UG. NF-κB-mediated repression of iNOS expression in Leishmania amazonensis macrophage infection. Immunol Lett 2009; 127:19-26. [DOI: 10.1016/j.imlet.2009.08.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 08/11/2009] [Accepted: 08/18/2009] [Indexed: 11/17/2022]
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Gomez MA, Contreras I, Hallé M, Tremblay ML, McMaster RW, Olivier M. Leishmania GP63 alters host signaling through cleavage-activated protein tyrosine phosphatases. Sci Signal 2009; 2:ra58. [PMID: 19797268 DOI: 10.1126/scisignal.2000213] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
With more than 12 million people affected worldwide, 2 million new cases occurring per year, and the rapid emergence of drug resistance and treatment failure, leishmaniasis is an infectious disease for which research on drug and vaccine development, host-pathogen, and vector-parasite interactions are current international priorities. Upon Leishmania-macrophage interaction, activation of the protein tyrosine phosphatase (PTP) SHP-1 rapidly leads to the down-regulation of Janus kinase and mitogen-activated protein kinase signaling, resulting in the attenuation of host innate inflammatory responses and of various microbicidal macrophage functions. We report that, in addition to SHP-1, the PTPs PTP1B and TCPTP are activated and posttranslationally modified in infected macrophages, and we identify an essential role for PTP1B in the in vivo progression of Leishmania infection. The mechanism underlying PTP modulation involves the proteolytic activity of the Leishmania surface protease GP63. Access of GP63 to macrophage PTP1B, TCPTP, and SHP-1 is mediated in part by a lipid raft-dependent mechanism, resulting in PTP cleavage and stimulation of phosphatase activity. Collectively, our data present a mechanism of cleavage-dependent activation of macrophage PTPs by an obligate intracellular pathogen and show that internalization of GP63, a key Leishmania virulence factor, into host macrophages is a strategy the parasite uses to interact and survive within its host.
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Affiliation(s)
- Maria Adelaida Gomez
- Department of Experimental Medicine, McGill University, Montréal, Québec, Canada
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Blanchette J, Abu-Dayyeh I, Hassani K, Whitcombe L, Olivier M. Regulation of macrophage nitric oxide production by the protein tyrosine phosphatase Src homology 2 domain phosphotyrosine phosphatase 1 (SHP-1). Immunology 2009; 127:123-33. [PMID: 18793215 DOI: 10.1111/j.1365-2567.2008.02929.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Nitric oxide (NO) is a potent molecule involved in the cytotoxic effects mediated by macrophages (MØ) against microorganisms. We previously reported that Src homology 2 domain phosphotyrosine phosphatase 1 (SHP-1)-deficient cells generate a greater amount of NO than wild-type cells in response to interferon-gamma (IFN-gamma). We also reported that the Leishmania-induced MØ SHP-1 activity is needed for the survival of the parasite within phagocytes through the attenuation of NO-dependent and NO-independent mechanisms. In the present study, we investigated the role of SHP-1 in regulating key signalling molecules important in MØ NO generation. Janus tyrosine kinase 2 (JAK2), mitogen-activated extracellular signal-regulated protein kinase kinase (MEK), extracellular signal-regulated kinases 1 and 2 (Erk1/Erk2) mitogen-activated protein kinases, p38 and stress-activated mitogen-activated protein kinases/c-Jun NH(2)-terminal kinase (SAPK/JNK) were examined in immortalized bone marrow-derived MØ (BMDM) from both SHP-1-deficient motheaten mice (me-3) and their respective littermates (LM-1). The results indicated that Erk1/Erk2 and SAPK/JNK are the main kinases regulated by SHP-1 because the absence of SHP-1 caused an increase in their phosphorylation. Moreover, only Apigenin, the specific inhibitor of Erk1/Erk2, was able to block IFN-gamma-induced inducible nitric oxide synthase (iNOS) transcription and translation in me-3 cells. Transcription factor analyses revealed that in the absence of SHP-1, activator protein-1 (AP-1) was activated. The activation of AP-1, and not nuclear factor-kappaB (NF-kappaB) or signal transducer and activator of transcription-1 alpha (STAT-1 alpha), may explain the enhanced NO generation in SHP-1-deficient cells. These observations emphasize the involvement of the MAPKs Erk1/Erk2 and SAPK/JNK in NO generation via AP-1 activation. Collectively, our findings suggest that SHP-1 plays a pivotal role in the negative regulation of signalling events leading to iNOS expression and NO generation. Furthermore, our observations underline the importance of SHP-1-mediated negative regulation in maintaining NO homeostasis and thus preventing the abnormal generation of NO that can be detrimental to the host.
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Leishmania-induced IRAK-1 inactivation is mediated by SHP-1 interacting with an evolutionarily conserved KTIM motif. PLoS Negl Trop Dis 2008; 2:e305. [PMID: 19104650 PMCID: PMC2596967 DOI: 10.1371/journal.pntd.0000305] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Accepted: 11/25/2008] [Indexed: 11/24/2022] Open
Abstract
Parasites of the Leishmania genus can rapidly alter several macrophage (MØ) signalling pathways in order to tame down the innate immune response and inflammation, therefore favouring their survival and propagation within their mammalian host. Having recently reported that Leishmania and bacterial LPS generate a significantly stronger inflammatory response in animals and phagocytes functionally deficient for the Src homology 2 domain-containing protein tyrosine phosphatase (SHP-1), we hypothesized that Leishmania could exploit SHP-1 to inactivate key kinases involved in Toll-like receptor (TLR) signalling and innate immunity such as IL-1 receptor-associated kinase 1 (IRAK-1). Here we show that upon infection, SHP-1 rapidly binds to IRAK-1, completely inactivating its intrinsic kinase activity and any further LPS-mediated activation as well as MØ functions. We also demonstrate that the SHP-1/IRAK-1 interaction occurs via an evolutionarily conserved ITIM-like motif found in the kinase domain of IRAK-1, which we named KTIM (Kinase Tyrosyl-based Inhibitory Motif). This regulatory motif appeared in early vertebrates and is not found in any other IRAK family member. Our study additionally reveals that several other kinases (e.g. Erk1/2, IKKα/β) involved in downstream TLR signalling also bear KTIMs in their kinase domains and interact with SHP-1. We thus provide the first demonstration that a pathogen can exploit a host protein tyrosine phosphatase, namely SHP-1, to directly inactivate IRAK-1 through a generally conserved KTIM motif. Leishmania developed several methods to seize control of macrophage signalling pathways in an effort to inactivate their killing abilities. One effective method utilized by the parasite is the activation of host protein tyrosine phosphatases, specifically SHP-1. This increased phosphatase activity contributes to the inactivation of signalling molecules involved in critical macrophage functions such as NO and cytokine production. Interestingly, the absence of SHP-1 results in stronger macrophage inflammatory responses to a bacterial cell wall component known as LPS, a molecule detected by macrophages through Toll-like receptors (TLRs). This observation suggested a role for SHP-1 in the regulation of TLR signalling. Our study reveals that upon Leishmania infection, SHP-1 is able to rapidly bind to and inactivate a critical kinase (IRAK-1) in this pathway. This regulatory binding was shown to be mediated by an evolutionarily conserved motif identified in the kinase. This motif was also present in other kinases involved in Toll signalling and therefore could represent a regulatory mechanism of relevance to many kinases. This work not only reports a unique mechanism by which Leishmania can avoid harmful TLR signalling, but also provides a platform on which extensive investigation on host evasion mechanisms and regulation of cellular kinases can be gained.
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Späth GF, McDowell MA, Beverley SM. Leishmania major intracellular survival is not altered in SHP-1 deficient mev or CD45-/- mice. Exp Parasitol 2008; 120:275-9. [PMID: 18682252 DOI: 10.1016/j.exppara.2008.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 07/07/2008] [Accepted: 07/14/2008] [Indexed: 01/23/2023]
Abstract
Protozoan parasites of the genus Leishmania escape from the immune response by interfering with signal transduction pathways of its host cell, the macrophage, thereby establishing permissive conditions for intracellular survival. Inhibition of macrophage activation after Leishmania infection has been suggested to require activation of the host cell phosphatase SHP-1. However, by utilizing infections of SHP-1 deficient (me(v)) and CD45 null mutant mice or macrophages, we provide evidence that intracellular survival of Leishmania major is not generally dependent on these cellular phosphatases.
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Affiliation(s)
- Gerald F Späth
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Caron D, Savard PE, Doillon CJ, Olivier M, Shink E, Lussier JG, Faure RL. Protein tyrosine phosphatase inhibition induces anti-tumor activity: Evidence of Cdk2/p27kip1 and Cdk2/SHP-1 complex formation in human ovarian cancer cells. Cancer Lett 2008; 262:265-75. [DOI: 10.1016/j.canlet.2007.12.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Revised: 11/13/2007] [Accepted: 12/05/2007] [Indexed: 10/22/2022]
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Gregory D, Godbout M, Contreras I, Forget G, Olivier M. A novel form of NF-κB is induced byLeishmaniainfection: Involvement in macrophage gene expression. Eur J Immunol 2008; 38:1071-81. [DOI: 10.1002/eji.200737586] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Identification of leishmania fructose-1,6-bisphosphate aldolase as a novel activator of host macrophage Src homology 2 domain containing protein tyrosine phosphatase SHP-1. Biochem Biophys Res Commun 2007; 364:601-7. [DOI: 10.1016/j.bbrc.2007.10.065] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 10/10/2007] [Indexed: 11/18/2022]
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Gomez MA, Li S, Tremblay ML, Olivier M. NRAMP-1 Expression Modulates Protein-tyrosine Phosphatase Activity in Macrophages. J Biol Chem 2007; 282:36190-8. [DOI: 10.1074/jbc.m703140200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Kima PE. The amastigote forms of Leishmania are experts at exploiting host cell processes to establish infection and persist. Int J Parasitol 2007; 37:1087-96. [PMID: 17543969 PMCID: PMC2043126 DOI: 10.1016/j.ijpara.2007.04.007] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2007] [Revised: 04/11/2007] [Accepted: 04/18/2007] [Indexed: 01/31/2023]
Abstract
Leishmania are dimorphic protozoan parasites that live as flagellated forms in the gut of their sandfly vector and as aflagellated forms in their mammalian hosts. Although both parasite forms can infect macrophages and dendritic cells, they elicit distinct responses from mammalian cells. Amastigotes are the parasites forms that persist in the infected host; they infect cells recruited to lesions and disseminate the infection to secondary sites. In this review I discuss studies that have investigated the mechanisms that Leishmania amastigotes employ to harness the host cell's response to infection. It should be acknowledged that our understanding of the mechanisms deployed by Leishmania amastigotes to modulate the host cell's response to infection is still rudimentary. Nonetheless, the results show that amastigote interactions with mammalian cells promote the production of anti-inflammatory cytokines such as IL-10 and TGF-beta while suppressing the production of IL-12, superoxide and nitric oxide. An underlying issue that is considered is how these parasites that reside in sequestered vacuolar compartments target host cell processes in the cytosol or the nucleus; does this occur through the release of parasite molecules from parasitophorous vacuoles or by engaging and sustaining signalling pathways throughout the course of infection?
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Affiliation(s)
- Peter E Kima
- Department of Microbiology and Cell Science, University of Florida, Building 981, Box 110700, Gainesville, FL 32611, USA.
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Lopez M, Cherkasov A, Nandan D. Molecular architecture of leishmania EF-1α reveals a novel site that may modulate protein translation: A possible target for drug development. Biochem Biophys Res Commun 2007; 356:886-92. [PMID: 17397800 DOI: 10.1016/j.bbrc.2007.03.077] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Accepted: 03/09/2007] [Indexed: 11/29/2022]
Abstract
Elongation factor-1alpha plays an essential role in eukaryotic protein biosynthesis. Recently, we have shown by protein structure modeling the presence of a hairpin-loop of 12 amino acids in mammalian EF-1alpha that is absent in the leishmania homologue [D. Nandan, A. Cherkasov, R. Sabouti, T. Yi, N.E. Reiner, Molecular cloning, biochemical and structural analysis of elongation factor-1 alpha from Leishmania donovani: comparison with the mammalian homologue, Biochem. Biophys. Res. Commun. 302 (2003) 646-652]. As a consequence of this deletion, an exposed region is available on the main body of leishmania EF-1alpha. Here we report the generation of an anti-EF-1alpha antibody (DN-3) which bound selectively to the exposed region of leishmania EF-1alpha, with no reactivity with human EF-1alpha. In a leishmania cell-free protein translation system, DN-3 substantially inhibited protein translation. A similar inhibitory effect was observed when a specific peptide based on the exposed region was used in the cell-free protein translation assay. The application of structure-based in silico methods to identify potential ligands to target the exposed region identified a small molecule that selectively attenuated in vitro translation using leishmania extracts. Moreover, this small molecule showed selective suppressive effect on multiplication of leishmania in culture. Taken together, these findings identify a novel, exposed region in leishmania EF-1alpha that may be involved in protein synthesis and a potential site for drug targeting.
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Affiliation(s)
- Martin Lopez
- Department of Medicine (Division of Infectious Diseases), University of British Columbia, Faculties of Medicine and Science, 2733 Heather Street, Heather Pavilion East, Room 452-D, Vancouver, BC, Canada V5Z 3J5
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Abstract
Leishmania are digenetic protozoan parasites that are inoculated into the skin by vector sand flies, are taken up by macrophages, and produce a spectrum of chronic diseases in their natural reservoir and susceptible human hosts. During the early establishment of infection in the skin and lymphoid organs, Leishmania produce multiple effects on macrophage and dendritic cell functions that inhibit their innate anti-microbial defenses and impair their capacity to initiate T-helper 1 cell immunity. In addition, the skin is a site preconditioned for early parasite survival by virtue of a high frequency of steady-state, natural CD25+Foxp3+ regulatory T cells (Tregs) that function to suppress the generation of unneeded immune responses to infectious and non-infectious antigens to which the skin is regularly exposed. In murine models of infection, antigen-induced CD25+/-Foxp3-interleukin (IL)-10+ Treg cells act during the effector phase of the immune response to control immunopathology and may also delay or prevent healing. Finally, following resolution of infection in healed mice, CD25+Foxp3+ Tregs function in an IL-10-dependent manner to prevent sterile cure and establish a long-term state of functional immune privilege in the skin.
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Affiliation(s)
- Nathan Peters
- Laboratory of Parasitic Diseases, NIAID, Bethesda, MD 20892-0425, USA
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Blanchette J, Pouliot P, Olivier M. Role of protein tyrosine phosphatases in the regulation of interferon-γ-induced macrophage nitric oxide generation: implication of ERK pathway and AP-1 activation. J Leukoc Biol 2006; 81:835-44. [PMID: 17170076 DOI: 10.1189/jlb.0505252] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
NO is a potent molecule involved in the cytotoxic events mediated by macrophages (MØ) against microorganisms. We reported previously that inhibition of MØ protein tyrosine phosphatases (PTPs) mediates a protective effect against Leishmania infection, which was NO-dependent. Herein, we show that the PTP inhibitors of the peroxovanadium (pV) class, bpV(phen) and bpV(pic), can similarly increase murine MØ IFN-gamma-induced NO generation. Using various second messenger (JAK2, MEK, Erk1/Erk2, and p38) antagonists, we found that the Erk1/Erk2 pathway was the principal pathway submitted to regulation by PTPs in the context of IFN-gamma-driven MØ activation and increase in NO production. We observed that bpV(phen) increases inducible NO synthase (iNOS) expression, resulting in enhanced NO production, whereas the bpV(pic) increase of NO production does not seem to result from a modulation of iNOS expression. Transcription factors STAT-1alpha and NF-kappaB, recognized for their importance in NO generation, were not affected by the pV treatment. However, AP-1 was strongly activated by bpV(phen) but not by bpV(pic). Collectively, our results suggest that increased IFN-gamma-induced NO production, observed after bpV(phen) treatment, involves the activation of the transcription factor AP-1 by Erk1/Erk2- and stress-activated protein kinase/JNK-dependent transduction mechanisms.
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Affiliation(s)
- Julie Blanchette
- Centre de Recherche en Infectiologie and Département de Biologie Médicale, Centre Hospitalier Universitaire de Québec, Pavillon CHUL, Université Laval, Ste-Foy, Québec, Canada
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Forget G, Gregory DJ, Whitcombe LA, Olivier M. Role of host protein tyrosine phosphatase SHP-1 in Leishmania donovani-induced inhibition of nitric oxide production. Infect Immun 2006; 74:6272-9. [PMID: 17057094 PMCID: PMC1695482 DOI: 10.1128/iai.00853-05] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In order to survive within the macrophages of its host organism, the protozoan parasite Leishmania inhibits a number of critical, gamma interferon (IFN-gamma)-inducible, macrophage functions, including the generation of nitric oxide. We have previously shown that the protein tyrosine phosphatase SHP-1 (Src-homology 2 domain containing phosphatase-1) is activated during Leishmania infection and plays an important role in both the survival of Leishmania within cultured macrophages and disease progression in vivo by inhibiting nitric oxide production. Here we use a SHP-1-/- macrophage cell line derived from motheaten mice to address the mechanisms by which SHP-1 prevents IFN-gamma-dependent nitric oxide production during Leishmania donovani infection. We show that Leishmania inhibits nitric oxide production in response to IFN-gamma poorly in SHP-1-deficient macrophages. This correlates with the inability of Leishmania to alter JAK2 and mitogen-activated protein kinase extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation and to prevent nuclear translocation of transcription factors NF-kappaB and AP-1, although the latter two to a lesser extent. Surprisingly, Leishmania inactivated the transcription factor STAT1 to a similar extent in SHP-1-deficient and wild-type macrophages, so STAT1 is not necessary for nitric oxide production by infected macrophages. Overall, this study demonstrates that induction of SHP-1 by Leishmania is vital for inhibition of nitric oxide generation and that this inhibition occurs through the inactivation of JAK2 and ERK1/2, and transcription factors NF-kappaB and AP-1.
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Affiliation(s)
- Geneviève Forget
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec, Canada
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Chang HK, Thalhofer C, Duerkop BA, Mehling JS, Verma S, Gollob KJ, Almeida R, Wilson ME. Oxidant generation by single infected monocytes after short-term fluorescence labeling of a protozoan parasite. Infect Immun 2006; 75:1017-24. [PMID: 17118986 PMCID: PMC1828521 DOI: 10.1128/iai.00914-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Leishmania spp. are intracellular protozoa residing in mononuclear phagocytes. Leishmania organisms are susceptible to microbicidal responses generated in response to phagocytosis. Assuming that both phagocyte and parasite populations are heterogeneous, it is advantageous to examine the response of individual cells phagocytosing living parasites. Because Leishmania spp. lose virulence during the raising of transfectants, we developed a method to label live Leishmania chagasi short-term with fluorescent dyes. Up to six parasite divisions were detected by flow cytometry after labeling with carboxyfluorescein diacetate succinimidyl ester (CFSE), dioctadecyl-tetramethylindo carbocyanine perchlorate, or chloromethyl tetramethylrhodamine. Labeled parasites entered mononuclear phagocytes as determined by confocal and time-lapse microscopy. Dihydroethidium (DHE) was used to detect macrophage-derived oxidants generated during phagocytosis. Presumably Leishmania organisms are opsonized with host serum/tissue components such as complement prior to phagocytosis. Therefore, we investigated the effects of opsonization and found that this increased the efficiency of CFSE-labeled parasite entry into monocytes (84.6% +/- 8.8% versus 20.2% +/- 3.8% monocytes infected; P < 0.001). Opsonization also increased the percentage of phagocytes undergoing a respiratory burst (66.0% +/- 6.3% versus 41.0% +/- 8.3% of monocytes containing CFSE-labeled parasites; P < 0.001) and the magnitude of oxidant generation by each infected monocyte. Inhibitor data indicated that DHE was oxidized by products of the NADPH oxidase. These data suggest that opsonized serum components such as complement lead to more efficient entry of Leishmania into their target cells but at the same time activate the phagocyte oxidase to generate microbicidal products in infected cells. The parasite must balance these positive and negative survival effects in order to initiate a viable infection.
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Affiliation(s)
- Haeok K Chang
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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Gazzinelli RT, Denkers EY. Protozoan encounters with Toll-like receptor signalling pathways: implications for host parasitism. Nat Rev Immunol 2006; 6:895-906. [PMID: 17110955 DOI: 10.1038/nri1978] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Toll-like receptors (TLRs) have emerged as a major receptor family involved in non-self recognition. They have a vital role in triggering innate immunity and orchestrate the acquired immune response during bacterial and viral infection. However, the role of TLRs during infection with protozoan pathogens is less clear. Nevertheless, our understanding of how these parasitic microorganisms engage the host TLR signalling system has now entered a phase of rapid expansion. This Review describes recent insights into how parasitic protozoans are sensed by TLR molecules, and how the TLR system itself can be targeted by these microbial pathogens for their own survival.
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Affiliation(s)
- Ricardo T Gazzinelli
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, 31270-901 Belo Horizonte, Brazil.
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45
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Bergeron M, Olivier M. Trypanosoma cruzi-Mediated IFN-γ-Inducible Nitric Oxide Output in Macrophages Is Regulated byiNOSmRNA Stability. THE JOURNAL OF IMMUNOLOGY 2006; 177:6271-80. [PMID: 17056557 DOI: 10.4049/jimmunol.177.9.6271] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although the effects of activated macrophages (Muphi) on the intracellular parasite Trypanosoma cruzi are well documented, little is known about how host-Muphi functions are affected by this pathogen before activation. This study is aimed at assessing the capacity of T. cruzi infection to modulate J77.4 murine Muphi NO generation following IFN-gamma stimulation, and identifying mechanisms regulating this modulation. Results show that parasite infection potentiates Muphi to produce inducible NO synthase (iNOS) mRNA and protein as well as NO following IFN-gamma stimulation above IFN-gamma alone controls. This potentiation occurs through the concomitant activation of NF-kappaB, ERK1/ERK2 MAPK, and stress-activated protein kinase signaling pathways. Activation of the JAK/STAT pathway by IFN-gamma then leads to STAT1alpha translocation and the transcription of a stable iNOS mRNA species. A decreased rate of iNOS mRNA degradation results in elevated levels of iNOS protein and NO production. Maximal iNOS expression is likely achieved through NF-kappaB activation by T. cruzi, whereas iNOS mRNA stability results from ERK1/ERK2 MAPK and stress-activated protein kinase activation by the infection. Taken together, our data show that T. cruzi-infected Muphi NO generation is controlled at both pre- and posttranscriptional levels and relies on signaling pathway cross-talk. This is the first report of a parasite pathogen capable of heightening host mRNA stability.
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Affiliation(s)
- Marc Bergeron
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Quebec, Pavillon Centre Hospitalier de l'Université Laval, and Département de Biologie Médicale, Faculté de Médecine, Université Laval, Sainte-Foy, Quebec, Canada G1V 4G2
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46
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Li YY, Jones SJM, Cherkasov A. Selective targeting of indel-inferred differences in spatial structures of homologous proteins. J Bioinform Comput Biol 2006; 4:403-14. [PMID: 16819791 DOI: 10.1142/s0219720006001898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2005] [Revised: 12/03/2005] [Accepted: 12/08/2005] [Indexed: 11/18/2022]
Abstract
The eukaryotic pathogen Leishmania donovani possesses a housekeeping protein Elongation-Factor-1alpha (EF-1alpha) which has been found to be unexpectedly involved in the pathogen's virulence. Because it is associated with virulence and essential for cell survival, this protein is an attractive choice for drug targeting; however, its sequence is highly similar (> 80% sequence identity) to that of its human homolog, rendering it a risky choice for a drug target. The chief difference between these two proteins has been found to be a 12 amino acid sequence present in human EF-1alpha but absent from leishmania EF-1alpha. Furthermore, it has been shown that this 12 amino acid insert in the human sequence corresponds to a hairpin loop on the surface of the protein. In this study, we searched for those spatial features in leishmania EF-1alpha that are impacted or obscured by the extra hairpin loop in the human counterpart. We have also conducted a large-scale in silico screening for small molecules that could plausibly bind to these protein features. While experimental evidence is required to verify our results, our findings thus far appear to support this approach as a new strategy for the development of antagonists against pathogenic targets having close human homologs.
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Affiliation(s)
- Yvonne Y Li
- CIHR/MSFHR Strategic Training Program in Bioinformatics, University of British Columbia, 570 West 7th Avenue, Vancouver, British Columbia, V5Z 4S6, Canada.
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Zhou Y, Bhattacharjee H, Mukhopadhyay R. Bifunctional role of the leishmanial antimonate reductase LmACR2 as a protein tyrosine phosphatase. Mol Biochem Parasitol 2006. [PMID: 16644029 DOI: doi/10.1016/j.molbiopara.2006.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
LmACR2 is the first identified antimonate reductase responsible for the reduction of pentavalent antimony in pentostam to the active trivalent form of the drug in Leishmania. LmACR2 is a homologue of the yeast arsenate reductase Acr2p and Cdc25 phosphatases and has the HC[X]5R phosphatase motif. Purified LmACR2 exhibited phosphatase activity in vitro and was able to dephosphorylate a phosphotyrosine residue from a synthetic peptide. This phosphatase activity was inhibited by classical inhibitors such as orthovanadate. LmACR2-catalyzed phosphatase activity was inhibited by either antimonate or arsenate. Site-directed mutagenesis experiments showed that the H74C[X]5R81 motif was involved in catalysis. This is the first report of a metalloid reductase with a bifunctional role in protein tyrosine phosphatase activity. Leishmania is never exposed to metalloids during its life cycle. It is therefore unlikely that it would evolve an enzyme exclusively for drug activation. We propose that the physiological function of LmACR2 is to dephosphorylate phosphotyrosine residues in leishmanial proteins.
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Affiliation(s)
- Yao Zhou
- Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA
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Cherkasov A, Nandan D, Reiner NE. Selective targeting of indel-inferred differences in spatial structures of highly homologous proteins. Proteins 2006; 58:950-4. [PMID: 15657927 DOI: 10.1002/prot.20391] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent findings have shown that the protein elongation factor-1alpha (EF-1alpha) from the eukaryotic pathogen Leishmania donovani possesses virulence properties. This was unexpected, since it has greater than 80% sequence identity with its human homologue. Given that EF-1alpha is essential for cell survival, in principle, it can be considered an attractive drug target. However, the challenge is to be able to selectively target the protein so as not to affect function of the human homologue. While a limited number of discrete differences were scattered throughout the sequence, most of the difference between these 2 homologues could be attributed to a 12-amino acid insert present in human EF-1alpha and absent from the leishmania sequence. In the present study, we modeled the spatial differences in structures of human and L. donovani EF-1alpha's inferred by this insertion-deletion (or "indel"). The protein models were used to develop antibodies directed specifically toward the deletion region of the pathogen protein. The strategy described allowed successful selective targeting of this putative leishmania virulence factor while avoiding recognition of the highly similar human EF-1alpha homologue. These findings may establish a new strategy for the development of antagonists directed against certain pathogenic targets having close human homologues.
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Affiliation(s)
- Artem Cherkasov
- Department of Medicine, Division of Infectious Diseases, University of British Columbia, Vancouver, British Columbia, Canada.
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Dubois MJ, Bergeron S, Kim HJ, Dombrowski L, Perreault M, Fournès B, Faure R, Olivier M, Beauchemin N, Shulman GI, Siminovitch KA, Kim JK, Marette A. The SHP-1 protein tyrosine phosphatase negatively modulates glucose homeostasis. Nat Med 2006; 12:549-56. [PMID: 16617349 DOI: 10.1038/nm1397] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Accepted: 03/17/2006] [Indexed: 12/17/2022]
Abstract
The protein tyrosine phosphatase SHP-1 is a well-known inhibitor of activation-promoting signaling cascades in hematopoietic cells but its potential role in insulin target tissues is unknown. Here we show that Ptpn6(me-v/me-v) (also known as viable motheaten) mice bearing a functionally deficient SHP-1 protein are markedly glucose tolerant and insulin sensitive as compared to wild-type littermates, as a result of enhanced insulin receptor signaling to IRS-PI3K-Akt in liver and muscle. Downregulation of SHP-1 activity in liver of normal mice by adenoviral expression of a catalytically inert mutant of SHP-1, or after small hairpin RNA-mediated SHP-1 silencing, further confirmed this phenotype. Tyrosine phosphorylation of CEACAM1, a modulator of hepatic insulin clearance, and clearance of serum [125I]-insulin were markedly increased in SHP-1-deficient mice or SHP-1-deficient hepatic cells in vitro. These findings show a novel role for SHP-1 in the regulation of glucose homeostasis through modulation of insulin signaling in liver and muscle as well as hepatic insulin clearance.
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Affiliation(s)
- Marie-Julie Dubois
- Department of Anatomy-Physiology and Lipid Research Unit, Laval University Hospital Research Center, 2705 Laurier Boulevard, Québec, Québec G1V 4G2, Canada
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Gregory DJ, Olivier M. Subversion of host cell signalling by the protozoan parasite Leishmania. Parasitology 2006; 130 Suppl:S27-35. [PMID: 16281989 DOI: 10.1017/s0031182005008139] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The protozoa Leishmania spp. are obligate intracellular parasites that inhabit the macrophages of their host. Since macrophages are specialized for the identification and destruction of invading pathogens, both directly and by triggering an innate immune response, Leishmania have evolved a number of mechanisms for suppressing some critical macrophage activities. In this review, we discuss how various species of Leishmania distort the host macrophage's own signalling pathways to repress the expression of various cytokines and microbicidal molecules (nitric oxide and reactive oxygen species), and antigen presentation. In particular, we describe how MAP Kinase and JAK/STAT cascades are repressed, and intracellular Ca2+ and the activities of protein tyrosine phosphatases, in particular SHP-1, are elevated.
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Affiliation(s)
- D J Gregory
- Centre for the Study of Host Resistance, Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
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