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Characterization and Proteomic Analysis of Plasma EVs Recovered from Healthy and Diseased Dogs with Canine Leishmaniosis. Int J Mol Sci 2023; 24:ijms24065490. [PMID: 36982564 PMCID: PMC10056832 DOI: 10.3390/ijms24065490] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 02/23/2023] [Accepted: 03/05/2023] [Indexed: 03/16/2023] Open
Abstract
Dogs are highly valued companions and work animals that are susceptible to many life-threatening conditions such as canine leishmaniosis (CanL). Plasma-derived extracellular vesicles (EVs), exploited extensively in biomarker discovery, constitute a mostly untapped resource in veterinary sciences. Thus, the definition of proteins associated with plasma EVs recovered from healthy and diseased dogs with a relevant pathogen would be important for biomarker development. For this, we recovered, using size-exclusion chromatography (SEC), EVs from 19 healthy and 20 CanL dogs’ plasma and performed proteomic analysis by LC-MS/MS to define their core proteomic composition and search for CanL-associated alterations. EVs-specific markers were identified in all preparations and also non-EVs proteins. Some EVs markers such as CD82 were specific to the healthy animals, while others, such as the Integrin beta 3 were identified in most samples. The EVs-enriched preparations allowed the identification of 529 canine proteins that were identified in both groups, while 465 and 154 were only identified in healthy or CanL samples, respectively. A GO enrichment analysis revealed few CanL-specific terms. Leishmania spp. protein identifications were also found, although with only one unique peptide. Ultimately, CanL-associated proteins of interest were identified and a core proteome was revealed that will be available for intra- and inter-species comparisons.
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Conde L, Maciel G, de Assis GM, Freire-de-Lima L, Nico D, Vale A, Freire-de-Lima CG, Morrot A. Humoral response in Leishmaniasis. Front Cell Infect Microbiol 2022; 12:1063291. [PMID: 36579347 PMCID: PMC9791258 DOI: 10.3389/fcimb.2022.1063291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022] Open
Abstract
Leishmaniasis presents different types of clinical manifestations that can be divided into cutaneous leishmaniasis and visceral leishmaniasis. The host's immune system, associated with genetic and nutritional factors, is strongly involved in the evolution of the disease or parasite escape. Humoral immunity is characterized by the production of antibodies capable of promoting neutralization, opsonization, and activation of the complement system. In this scenario, B lymphocytes produce antibodies that play an important role in Leishmania infection although neglected for a long time. Thus, relevant aspects in the establishment of Leishmania infection will be addressed, highlighting the importance of humoral immunity during the entire process of Leishmania infection.
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Affiliation(s)
- Luciana Conde
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gabriela Maciel
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Meira de Assis
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leonardo Freire-de-Lima
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Dirlei Nico
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - André Vale
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Alexandre Morrot
- Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil,Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil,*Correspondence: Alexandre Morrot,
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Gupta AK, Das S, Kamran M, Ejazi SA, Ali N. The Pathogenicity and Virulence of Leishmania - interplay of virulence factors with host defenses. Virulence 2022; 13:903-935. [PMID: 35531875 PMCID: PMC9154802 DOI: 10.1080/21505594.2022.2074130] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Leishmaniasis is a group of disease caused by the intracellular protozoan parasite of the genus Leishmania. Infection by different species of Leishmania results in various host immune responses, which usually lead to parasite clearance and may also contribute to pathogenesis and, hence, increasing the complexity of the disease. Interestingly, the parasite tends to reside within the unfriendly environment of the macrophages and has evolved various survival strategies to evade or modulate host immune defense. This can be attributed to the array of virulence factors of the vicious parasite, which target important host functioning and machineries. This review encompasses a holistic overview of leishmanial virulence factors, their role in assisting parasite-mediated evasion of host defense weaponries, and modulating epigenetic landscapes of host immune regulatory genes. Furthermore, the review also discusses the diagnostic potential of various leishmanial virulence factors and the advent of immunomodulators as futuristic antileishmanial drug therapy.
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Affiliation(s)
- Anand Kumar Gupta
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Sonali Das
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Mohd Kamran
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Sarfaraz Ahmad Ejazi
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Nahid Ali
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
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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: 105] [Impact Index Per Article: 8.8] [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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Sudan R, Srivastava N, Pandey SP, Majumdar S, Saha B. Reciprocal Regulation of Protein Kinase C Isoforms Results in Differential Cellular Responsiveness. THE JOURNAL OF IMMUNOLOGY 2012; 188:2328-37. [DOI: 10.4049/jimmunol.1101678] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Quintana E, Torres Y, Alvarez C, Rojas A, Forero ME, Camacho M. Changes in macrophage membrane properties during early Leishmania amazonensis infection differ from those observed during established infection and are partially explained by phagocytosis. Exp Parasitol 2010; 124:258-64. [PMID: 19854174 DOI: 10.1016/j.exppara.2009.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 10/14/2009] [Accepted: 10/19/2009] [Indexed: 12/01/2022]
Affiliation(s)
- Eduardo Quintana
- Laboratorio de Biofísica, Centro Internacional de Física, Bogotá, Colombia
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7
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Späth GF, Schlesinger P, Schreiber R, Beverley SM. A novel role for Stat1 in phagosome acidification and natural host resistance to intracellular infection by Leishmania major. PLoS Pathog 2009; 5:e1000381. [PMID: 19381261 PMCID: PMC2663844 DOI: 10.1371/journal.ppat.1000381] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 03/16/2009] [Indexed: 01/14/2023] Open
Abstract
Intracellular parasites of the genus Leishmania generate severe diseases in humans, which are associated with a failure of the infected host to induce a protective interferon γ (IFNγ)-mediated immune response. We tested the role of the JAK/STAT1 signaling pathway in Leishmania pathogenesis by utilizing knockout mice lacking the signal transducer and activator of transcription 1 (Stat1) and derived macrophages. Unexpectedly, infection of Stat1-deficient macrophages in vitro with promastigotes from Leishmania major and attenuated LPG1 knockout mutants (lpg−) specifically lacking lipophosphoglycan (LPG) resulted in a twofold increased intracellular growth, which was independent of IFNγ and associated with a substantial increase in phagosomal pH. Phagosomes in Stat1−/− macrophages showed normal maturation as judged by the accumulation of the lysosomal marker protein rab7, and provided normal vATPase activity, but were defective in the anion conductive pathway required for full vesicular acidification. Our results suggest a role of acidic pH in the control of intracellular Leishmania growth early during infection and identify for the first time an unexpected role of Stat1 in natural anti-microbial resistance independent from its function as IFNγ-induced signal transducer. This novel Stat1 function may have important implications to studies of other pathogens, as the acidic phagolysosomal pH plays an important role in antigen processing and the uncoating process of many viruses. Protozoan parasites of the genus Leishmania generate a variety of pathologies, collectively termed leishmaniasis, which afflict millions of people worldwide. Leishmania is transmitted during the blood meal of infested sand flies that inoculate highly infective metacyclic promastigotes into the mammalian host. Following uptake by host macrophages, metacyclics differentiate into the amastigote form that replicates inside the acidified phago-lysosome of the host cell. The cytokine interferon-γ activates infected macrophages to kill intracellular Leishmania through the production of nitric oxide. This process is mediated through Stat 1, a cytosolic transcription factor that translocates into the nucleus in response to the cytokine, where it induces a pleiotropic anti-microbial response. By utilizing Stat1-deficient macrophages we found evidence for a novel interferon-γ-independent physiological function of Stat1 in acidification of the host cell phago-lysosome. Stat1-deficient macrophages showed higher phago-lysosomal pH and increased susceptibility to Leishmania infection, which was linked to a defect in cellular chloride channel function. Vesicular pH and acidification are important factors affecting the infective cycle of bacterial and protozoan pathogens, and the uncoating process during viral entry. Thus, the role of cytokine-independent Stat1 functions in innate anti-microbial resistance may have a greater impact on host-pathogen interactions than previously appreciated.
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Affiliation(s)
- Gerald F. Späth
- Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri, United States of America
- Department of Parasitology and Mycology, Laboratory of Parasite Virulence, Institut Pasteur, Paris, France
- Institut National de la Santé et de la Recherche Médicale (INSERM) AVENIR, Paris, France
| | - Paul Schlesinger
- Department of Cell Biology, Washington University Medical School, St. Louis, Missouri, United States of America
| | - Robert Schreiber
- Department of Pathology and Immunology, Washington University Medical School, St. Louis, Missouri, United States of America
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri, United States of America
- * E-mail:
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Camacho M, Forero ME, Fajardo C, Niño A, Morales P, Campos H. Leishmania amazonensis infection may affect the ability of the host macrophage to be activated by altering their outward potassium currents. Exp Parasitol 2008; 120:50-6. [PMID: 18571651 DOI: 10.1016/j.exppara.2008.04.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 04/22/2008] [Accepted: 04/28/2008] [Indexed: 02/04/2023]
Abstract
Understanding the impact of intracellular pathogens on the behaviour of their host cells is key to designing new interventions. We are interested in how Leishmania alters the electrical functioning of the plasma membrane of the macrophage it infects. The specific question addressed here is whether Leishmania amazonensis infection alters the macrophage's outward currents and what the consequences of such changes might be. Using the whole cell configuration of the patch clamp technique, we show that outward peak current density remains constant over the period studied but that time to peak and sensitivity to inhibitors vary during infection. Infected cells take 40% longer to activate and are more sensitive to the potassium channel inhibitor tetraethyl ammonium, compared to control cells, indicating increased potassium outward current activity. Activation of macrophages is associated with increases of nitric oxide production and membrane area, depolarization of the macrophage membrane, down regulation of inward potassium and up regulation of outward currents. After Leishmania infection, macrophage activation is characterised by a reduction of nitric oxide production and of outward current density. We therefore suggest that this reflects a weaker activation.
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Affiliation(s)
- Marcela Camacho
- Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia.
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9
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Dey R, Khan S, Pahari S, Srivastava N, Jadhav M, Saha B. Functional paradox in host–pathogen interaction dictates the fate of parasites. Future Microbiol 2007; 2:425-37. [PMID: 17683278 DOI: 10.2217/17460913.2.4.425] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The interactions between the protozoan parasite Leishmania and host macrophages are complex and involve several paradoxical functions that are meant for protection of the host but exploited by the parasite for its survival. The initial interaction of the parasite surface molecules with the host-cell receptors plays a major role in the final outcome of the disease state. While the interactions between macrophages and a virulent strain of Leishmania trigger a cascade of cell-signaling events leading to immunosuppression, the interaction with an avirulent strain triggers host-protective immune effector functions. Thus, an incisive study on Leishmania–macrophage interactions reveals functional paradoxes that highlight the concept of ‘relativity in parasite virulence’. Using Leishmania infection as a model, we propose that virulence of a pathogen and the resistance (or susceptibility) of a host to the pathogen are relative properties that equate to combinatorial functions of several sets of molecular processes.
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Affiliation(s)
- Ranadhir Dey
- National Centre for Cell Science, Ganeshkhind, Pune, India.
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10
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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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11
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Olivier M, Gregory DJ, Forget G. Subversion mechanisms by which Leishmania parasites can escape the host immune response: a signaling point of view. Clin Microbiol Rev 2005; 18:293-305. [PMID: 15831826 PMCID: PMC1082797 DOI: 10.1128/cmr.18.2.293-305.2005] [Citation(s) in RCA: 362] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The obligate intracellular parasite Leishmania must survive the antimicrobial activities of its host cell, the macrophage, and prevent activation of an effective immune response. In order to do this, it has developed numerous highly successful strategies for manipulating activities, including antigen presentation, nitric oxide and oxygen radical generation, and cytokine production. This is generally the result of interactions between Leishmania cell surface molecules, particularly gp63 and LPG, and less well identified macrophage surface receptors, causing the distortion of specific intracellular signaling cascades. We describe some of the signaling pathways and intermediates that are repressed in infected cells, including JAK/STAT, Ca(2+)-dependent protein kinase C (PKC) isoforms, and mitogen-activated protein kinases (especially ERK1/2), and proteasome-mediated transcription factor degradation. We also discuss protein tyrosine phosphatases (particularly SHP-1), intracellular Ca2+, Ca(2+)-independent PKC, ceramide, and the suppressors of cytokine signaling family of repressors, which are all reported to be activated following infection, and the role of parasite-secreted cysteine proteases.
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Affiliation(s)
- Martin Olivier
- Centre for the Study of Host Resistance at the Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.
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Abstract
During the course of evolution, protozoan parasites have developed strategies to subvert the immune response of their host in order to multiply, reproduce and survive. One of these inherited strategies is their capacity to modulate the host cell transductional mechanisms in their favor. Alteration of host cells Ca(2-) homeostasis following interaction and/or invasion by protozoan parasites such as Leishmania donovani, Trypanosoma cruzi, Plasmodium falciparum or Entamoeba histolytica has been reported. There is direct evidence that such disturbances are responsible for pathogenesis observed during parasitic infections. This homeostatic imbalance of Ca(2+) in the host cell is an early inducible event whose underlying mechanisms needs further investigation, as discussed here by Martin Olivier.
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Affiliation(s)
- M Olivier
- Centre de Recherche en Infectiologie, 9500, Centre Hospitalier de l'Université Laval, and Département de Microbiologie, Faculté de Médecine, Université Laval, 2705 boulevard Laurier, Ste-Foy, Québec, Canada.
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Genois N, Barbeau B, Olivier M, Tremblay MJ. Inhibition of HIV-1-mediated syncytium formation and virus replication by the lipophosphoglycan from Leishmania donovani is due to an effect on early events in the virus life cycle. Clin Exp Immunol 2001; 124:32-42. [PMID: 11359440 PMCID: PMC1906040 DOI: 10.1046/j.1365-2249.2001.01492.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous findings have indicated that the major surface molecule of Leishmania, lipophosphoglycan (LPG), could abrogate HIV-1-induced syncytium formation and virus replication. In the present work, we were interested in characterizing this inhibitory process. Data from a new luciferase-based semiquantitative assay for syncytium formation, relying on the coincubation of a T-cell line containing an HIV-1 LTR-driven luciferase construct with a cell line chronically infected with HIV-1, confirmed that LPG was indeed a strong inhibitor of HIV-1-dependent syncytium formation and that this inhibition was dose-dependent. As determined by flow cytometric analyses, this inhibition was not apparently due to downregulation of CD4, CXCR4 or LFA-1, three distinct surface glycoproteins known to be important in HIV-1 mediated syncytium formation. Furthermore, LPG did not seem to affect signal transduction pathways in T cells as judged by measurement of HIV-1 LTR-driven reporter gene activity upon treatment with different stimuli. However, pretreatment of either of the cell lines used in the assay with LPG led to a significant decrease of virus-mediated syncytium formation, which was further accentuated when both cell lines were pretreated. LPG inhibition of HIV-1 replication was next assessed. When measuring either infection with luciferase-encoding recombinant HIV-1 particles or multinucleated giant cell formation following an acute virus infection, we again observed that LPG was efficient at blocking HIV-1 replication. Specific assays probing different steps of viral entry demonstrated that attachment was not hindered by LPG but that viral entry was modulated, suggesting that LPG targets a postbinding step. Hence, incorporation of LPG into a target cell membrane could influence its fluidity and diminish both the virus-cell and cell-to-cell fusion processes initiated by HIV-1.
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Affiliation(s)
- N Genois
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec, Pavillon CHUL, Canada
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Bouchot A, Jaillet JD, Bonhomme A, Alessandro NP, Laquerriere P, Kilian L, Burlet H, Gomez-Marin JE, Pluot M, Bonhomme P, Pinon JM. Detection and localization of a Ca2+-ATPase activity in Toxoplasma gondii. Cell Struct Funct 2001; 26:49-60. [PMID: 11345503 DOI: 10.1247/csf.26.49] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Toxoplasma gondii, the agent causing toxoplasmosis, is an obligate intracellular protozoan parasite. A calcium signal appears to be essential for intracellular transduction during the active process of host cell invasion. We have looked for a Ca2+-transport ATPase in tachyzoites and found Ca2+-ATPase activity (11-22 nmol Pi liberated/mg protein/min) in the tachyzoite membrane fraction. This ATP-dependent activity was stimulated by Ca2+ and Mg2+ ions and by calmodulin, and was inhibited by pump inhibitors (sodium orthovanadate or thapsigargin). We used cytochemistry and X-ray microanalysis of cerium phosphate precipitates and immunolabelling to find the Ca2+, Mg2+-ATPase. It was located mainly in the membrane complex, the conoid, nucleus, secretory organelles (rhoptries, dense granules) and in vesicles with a high calcium concentration. Thus, Toxoplasma gondii possesses Ca2+-pump ATPase (Ca2+, Mg2+-ATPase) as do eukaryotic cells.
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Affiliation(s)
- A Bouchot
- UPRES EA 2070 et Laboratoire de Parasitologie-Mycologie, CHU Maison Blanche, Reims, France.
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Abstract
Cell surface lipophosphoglycan (LPG) is commonly regarded as a multifunctional Leishmania virulence factor required for survival and development of these parasites in mammals. In this study, the LPG biosynthesis gene lpg1 was deleted in Leishmania mexicana by targeted gene replacement. The resulting mutants are deficient in LPG synthesis but still display on their surface and secrete phosphoglycan-modified molecules, most likely in the form of proteophosphoglycans, whose expression appears to be up-regulated. LPG-deficient L.mexicana promastigotes show no significant differences to LPG-expressing parasites with respect to attachment to, uptake into and multiplication inside macrophages. Moreover, in Balb/c and C57/BL6 mice, LPG-deficient L.mexicana clones are at least as virulent as the parental wild-type strain and lead to lethal disseminated disease. The results demonstrate that at least L. mexicana does not require LPG for experimental infections of macrophages or mice. Leishmania mexicana LPG is therefore not a virulence factor in the mammalian host.
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Affiliation(s)
- T Ilg
- Max-Planck-Institut für Biologie, Corrensstrasse 38, D-72076 Tübingen, Germany.
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16
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Abstract
Leishmaniasis is a major health problem to humans and is caused by one of the world's major pathogens, the Leishmania parasite. These protozoa have the remarkable ability to avoid destruction in hostile environments they encounter throughout their life cycle. That Leishmania parasites have adapted to not only survive, but to proliferate largely is due to the protection conferred by unique glycoconjugates that are either on the parasites' cell surface or secreted. Most of these specialized molecules are members of a family of phosphoglycans while others are a family of glycosylinositol phospholipids. Together they have been implicated in a surprisingly large number of functions for the parasites throughout their life cycle and, therefore, are key players in their pathogenesis. This review summarizes the biological roles of these glycoconjugates and how they are believed to contribute to Leishmania survival in destructive surroundings.
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Affiliation(s)
- A Descoteaux
- Institut Armand-Frappier, Université du Québec, Laval, Canada
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17
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Abstract
Whereas amastigotes of the protozoan parasite Leishmania proliferate inside acidic phagolysosomal vacuoles of the macrophage, vacuoles induced by Leishmania donovani promastigotes during initiation of infection are poorly characterized. Here, evidence is presented that interaction of these parasitophorous vacuoles with endocytic organelles is very limited. In contrast, vacuoles formed around L. donovani mutants lacking the cell surface lipophosphoglycan (LPG) fuse extensively with endosomes and lysosomes. The role of LPG repeating units in the inhibition of phagosome-endosome fusion was demonstrated using two different approaches. First, genetic complementation of the LPG-defective C3PO mutant restored its ability to inhibit phagosome-endosome fusion to a degree similar to that of wild-type promastigotes. Second, opsonization of C3PO mutant cells with purified L. donovani LPG also conferred to this mutant the ability to inhibit phagosome-endosome fusion. Inasmuch as LPG is essential for infecting macrophages, these results suggest that inhibition of phagolysosomal biogenesis by LPG repeating units represents an intramacrophage survival strategy used by promastigotes to establish infection.
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Affiliation(s)
- M Desjardins
- Département d'anatomie,Université de Montréal, Montréal, Québec, Canada, H3C 3J7
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Racoosin EL, Beverley SM. Leishmania major: promastigotes induce expression of a subset of chemokine genes in murine macrophages. Exp Parasitol 1997; 85:283-95. [PMID: 9085925 DOI: 10.1006/expr.1996.4139] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recent studies suggest that Leishmania major promastigotes infect cultured macrophages in a stealthy fashion, activating little or no host gene expression and often interfering with the host's ability to respond to further stimulation. Here we examined macrophage transcription at early times following infection, when virulent parasites must execute steps required for survival. Stationary-phase promastigotes induced rapid and transient expression of transcripts of the chemokines JE (human MCAF/MCP-1) and KC (human GRO) in bone marrow-derived macrophages from BALB/c mice. JE and KC expression rose four- to sixfold shortly after infection and returned to uninduced levels by 4-24 hr. In contrast, chemokines MIP-1alpha, C10, and RANTES were not induced, nor were TGF-beta, IL-10, IL-12, or i-NOS. Chemokine induction did not occur following ingestion of latex beads, implicating a parasite-specific stimulus. Elevated expression of a subset of chemokines is the earliest known transcriptional response of macrophages to L. major infection and potentially may provide a signal for the initiation of downstream immunological responses which occur in vivo, such as cytokine induction and chemotaxis of monocytes and macrophages. Thus, Leishmania has a remarkable ability to take an active role in either inducing or preventing the expression of distinct sets of host genes during macrophage invasion and successful intracellular parasitism.
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Affiliation(s)
- E L Racoosin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, U.S.A.
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Mauël J. Intracellular survival of protozoan parasites with special reference to Leishmania spp., Toxoplasma gondii and Trypanosoma cruzi. ADVANCES IN PARASITOLOGY 1996; 38:1-51. [PMID: 8701794 DOI: 10.1016/s0065-308x(08)60032-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- J Mauël
- Institute of Biochemistry, Epalinges, Switzerland
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Descoteaux A, Turco SJ. The lipophosphoglycan of Leishmania and macrophage protein kinase C. ACTA ACUST UNITED AC 1993; 9:468-71. [PMID: 15463696 DOI: 10.1016/0169-4758(93)90105-o] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Lipophosphoglycan (LPG), the major cellsurface glycoconjugate of Leishmania promastigotes, is on essential virulence determinant. One feature of LPG resides in its strong inhibitory effect on the activity of purified protein kinase C (PKC). In this article, Albert Descoteaux and Salvatore Turco briefly review the evidence that LPG effectively inhibits PKC activity in the macrophage, and discuss the implication of such inhibition on Leishmania intramacrophoge survival.
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Affiliation(s)
- A Descoteaux
- Department of Biochemistry, University of Kentucky Medical Center, Lexington, KY 40536, USA
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21
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Shankar A, Mitchen TK, Hall LR, Turco SJ, Titus RG. Reversion to virulence in Leishmania major correlates with expression of surface lipophosphoglycan. Mol Biochem Parasitol 1993; 61:207-16. [PMID: 8264725 DOI: 10.1016/0166-6851(93)90067-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
An attenuated clone of Leishmania major was produced by chemical mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and was biochemically characterized to determine the reason(s) for its loss of virulence. We found that the degree of virulence of L. major did not correlate with either the level of expression of promastigote surface protease (PSP) or with the enzymatic activity of the molecule. In contrast, the levels of lipophosphoglycan (LPG) expressed by the attenuated clone were found to be at least 6-fold less than those of virulent L. major. When the attenuated L. major was injected into BALB/c mice and allowed to revert to virulence, the degree of reversion to virulence that the parasites underwent correlated directly with the amount and form (metacyclic) of LPG expressed by the parasites. Thus, these results further implicate LPG as an important Leishmania virulence factor.
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Affiliation(s)
- A Shankar
- Department of Tropical Public Health, Harvard School of Public Health, Boston, MA 02115
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22
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McConville MJ, Ferguson MA. The structure, biosynthesis and function of glycosylated phosphatidylinositols in the parasitic protozoa and higher eukaryotes. Biochem J 1993; 294 ( Pt 2):305-24. [PMID: 8373346 PMCID: PMC1134455 DOI: 10.1042/bj2940305] [Citation(s) in RCA: 674] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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23
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Greis K, Turco S, Thomas J, McConville M, Homans S, Ferguson M. Purification and characterization of an extracellular phosphoglycan from Leishmania donovani. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42635-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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24
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Affiliation(s)
- S J Turco
- Department of Biochemistry, University of Kentucky Medical Center, Lexington 40536
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25
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26
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Hall BF, Joiner KA. Strategies of obligate intracellular parasites for evading host defences. IMMUNOLOGY TODAY 1991; 12:A22-7. [PMID: 2069674 DOI: 10.1016/s0167-5699(05)80007-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
During the course of establishing infection in a susceptible host, obligate intracellular parasites evade host defence mechanisms before, during and after entry into host cells. Before entry they circumvent the lytic activity of the complement cascade, during cell entry they avoid being killed by toxic oxygen metabolites and after entry they escape nonoxidative killing mechanisms such as degradation by lysosomal hydrolases. Different intracellular parasites, exemplified here by Leishmania spp, Trypanosoma cruzi and Toxoplasma gondii, undermine host defences at each step by various strategies that ultimately ensure their targeting to, and survival in, an appropriate intracellular compartment.
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Affiliation(s)
- B F Hall
- Dept of Medicine, Yale University School of Medicine, New Haven, CT 06510-8056
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27
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Ganguly NK, Sodhi S, Kaul N, Kaur S, Malla N, Mahajan RC. Effect of nifedipine on Leishmania donovani infection in-vivo and in-vitro: chemiluminescence responses of peritoneal macrophages and neutrophils. J Pharm Pharmacol 1991; 43:140-2. [PMID: 1672903 DOI: 10.1111/j.2042-7158.1991.tb06652.x] [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] [Indexed: 12/28/2022]
Abstract
After peritoneal macrophages had been exposed to different concentrations of nifedipine (10-120 ng mL-1) there was a significant increase (P less than 0.001) in the percentage of Leishmania donovani infected macrophages compared with controls. Parasite load was also significantly increased (P less than 0.001) in nifedipine-treated, L. donovani infected, BALB/c mice, compared with untreated, infected mice, post-inoculation. Peak chemiluminescence responses were significantly depressed (P less than 0.001) in nifedipine-treated infected mice compared with untreated mice post-inoculation. It is suggested that availability of intracellular calcium is a factor in the defense mechanism of inflammatory cells in L. donovani infections.
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Affiliation(s)
- N K Ganguly
- Department of Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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28
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Osuna A, Castanys S, Rodriguez-Cabezas MN, Gamarro F. Trypanosoma cruzi: calcium ion movement during internalization in host HeLa cells. Int J Parasitol 1990; 20:673-6. [PMID: 2228428 DOI: 10.1016/0020-7519(90)90126-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The role of cytosolic Ca2+ and cytoplasmic calcium movement during the parasitization of HeLa cells by T. cruzi were studied. The level of calcium in parasitized cells increased compared to the control cells. Our experiments demonstrate that this cytosolic calcium originates from the release of the intracellular calcium deposits, especially from the mitochondria of the host cell. The parasitization rates decreased after the cells were treated with drugs to increase the cytosolic Ca2+ levels to inhibit the host-cell calmodulin.
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Affiliation(s)
- A Osuna
- Institute of Biotechnology, University of Granada, Science Faculty Campus Fuente Nueva C/Severo Ochoa, Spain
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29
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Vercesi AE, Macedo DV, Lima SA, Gadelha FR, Docampo R. Ca2+ transport in digitonin-permeabilized trypanosomatids. Mol Biochem Parasitol 1990; 42:119-24. [PMID: 2233896 DOI: 10.1016/0166-6851(90)90119-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The use of digitonin to permeabilize Leishmania mexicana mexicana, Leishmania agamae, and Crithidia fasciculata plasma membranes enabled us to study Ca2+ transport in situ. The present results show that the mitochondria of these trypanosomatids are able to build up and retain a membrane potential as indicated by a tetraphenylphosphonium-sensitive electrode. Ca2+ uptake caused membrane depolarization compatible with the existence of an electrogenically mediated Ca2+ transport mechanism in these mitochondria. Ca2+ uptake was partially inhibited by ruthenium red, almost totally inhibited by carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and stimulated by inorganic phosphate. Large amounts of Ca2+ were retained by C. fasciculata mitochondria even after addition of thiols and NAD(P)H oxidants such as t-butylhydroperoxide and diamide. In contrast, Ca2+ was not retained in the matrix of Leishmania sp. mitochondria for long periods of time. In addition to the mitochondrial Ca2+ uptake, a vanadate-sensitive Ca2(+)-transporting system was also detectable in these trypanosomatids.
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Affiliation(s)
- A E Vercesi
- Departamento de Bioquimica, Instituto de Biologia, UNICAMP, Campinas, S.P., Brazil
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30
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Abstract
Leishmania have long been known to clinicians and parasitologists as the causative agents of a variety of acute or chronic, cutaneous or visceral diseases in mammalian hosts. More recently, these protozoan parasites have evoked the interest of immunologists, as Leishmania infections are an excellent model for studying T-cell dominated antiparasite immune responses. In this review, Christian Bogdan, Martin Röllinghoff and Werner Solbach discuss the multiple interactions of Leishmania with components of the host immune system that illustrate the variety of highly elaborate evasion strategies developed by this parasite.
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Affiliation(s)
- C Bogdan
- Institute of Clinical Microbiology, University of Erlangen - Nürnberg, Wasserturmstrasse 3, D-8520 Erlangen, FRG
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31
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Prina E, Antoine JC, Wiederanders B, Kirschke H. Localization and activity of various lysosomal proteases in Leishmania amazonensis-infected macrophages. Infect Immun 1990; 58:1730-7. [PMID: 2187806 PMCID: PMC258715 DOI: 10.1128/iai.58.6.1730-1737.1990] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In mammalian hosts, Leishmania amastigotes are obligatory intracellular parasites of macrophages and multiply within parasitophorous vacuoles of phagolysosomal origin. To understand how they escape the harmful strategies developed by macrophages to kill ingested microorganisms, it is important to obtain information on the functional state of parasitophorous vacuole. For this purpose, we studied the intracellular distribution and activity of host lysosomal proteases in rat bone marrow-derived macrophages infected with Leishmania amazonensis amastigotes. Localization of cathepsins B, H, L, and D was investigated by using specific immunoglobulins. In uninfected macrophages, these enzymes were located in perinuclear granules (most of them were probably secondary lysosomes) which, after infection, disappeared progressively. In infected macrophages, cathepsins were detected mainly in the parasitophorous vacuoles, suggesting that the missing secondary lysosomes had fused with these organelles. Biochemical assays of various proteases (cathepsins B, H, and D and dipeptidyl peptidases I and II) showed that infection was accompanied by a progressive increase of all activities tested, except that of dipeptidyl peptidase II, which remained constant. No more than 1 to 10% of these activities could be attributed to amastigotes. These data indicate that (i) Leishmania infection is followed by an increased synthesis and/or a reduced catabolism of host lysosomal proteases, and (ii) amastigotes grow in a compartment rich in apparently fully active proteases. Unexpectedly, it was found that infected and uninfected macrophages degraded endocytosed proteins similarly. The lack of correlation in infected macrophages between increase of protease activities and catabolism of exogenous proteins could be linked to the huge increase in volume of the lysosomal compartment.
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Affiliation(s)
- E Prina
- Département de Physiopathologie Expérimentale, Unité d'Immunophysiologie Cellulaire de l'Institut Pasteur et du Centre National de la Recherche Scientifique, Paris, France
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32
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Schlein Y, Schnur LF, Jacobson RL. Released glycoconjugate of indigenous Leishmania major enhances survival of a foreign L. major in Phlebotomus papatasi. Trans R Soc Trop Med Hyg 1990; 84:353-5. [PMID: 2260168 DOI: 10.1016/0035-9203(90)90315-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The effect of Leishmania glycoconjugate in the vector was investigated using Phlebotomus papatasi artificially infected with a Leishmania major strain that this vector does not transmit in nature. Glycoconjugate of the vector-specific strain of L. major was added to the infective meals of some fly groups and the success of infections with or without this substance was compared 4 d later. In the absence of glycoconjugate the parasites survived in 15.6% of the flies, while the addition of 0.5 mg/ml and 2 mg/ml raised the rate of infection to 34.3% and 63.0% respectively. Undigested blood was found in the stomach of 7.8% of the infected flies, whereas following meals with parasites and 2 mg/ml glycoconjugate it was present in 37% of the flies. The results demonstrated that this glycoconjugate increased the viability of the parasites in the unsuitable vector and delayed digestion of the infective meals. In a parallel experiment the glycoconjugate of L. donovani did not affect the survival of the parasites.
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Affiliation(s)
- Y Schlein
- Department of Parasitology, Hadassah Medical School, Jerusalem, Israel
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33
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el-On J, Zvillich M, Sarov I. Leishmania major: inhibition of the chemiluminescent response of human polymorphonuclear leukocytes by promastigotes and their excreted factors. Parasite Immunol 1990; 12:285-95. [PMID: 2385444 DOI: 10.1111/j.1365-3024.1990.tb00955.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effect of various leishmanial preparations on the chemiluminescent response (CR) of human polymorphonuclear leukocytes (PMN) was studied. Almost no CR was observed with PMN stimulated with either Leishmania promastigotes or their excreted factors (EFs). Promastigotes added to PMN stimulated with phorbol myristate acetate (PMA), at a proportion of 20 to 1, respectively inhibited approximately 80-83% of the CR activity. Leishmanial promastigotes, whether live or dead, infective or non-infective as well as whole parasite homogenates, soluble and insoluble fractions, all decreased the CR of the PMN (PMN-CR). A similar effect was also observed with leishmanial EFs. The degree of inhibition was dose dependent and increasing the amount of EFs in the reaction mixture resulted in decrease of the PMN-CR. More than 80% of the total activity of the PMN-CR was inhibited by 500 micrograms EFs added at zero time to the reaction mixture. The inhibition of PMN-CR obtained from a patient suffering from a chronic infection caused by L. major was not significantly different from that observed with PMN from normal donors. The present study suggests that the PMN-CR is impaired by the Leishmania parasites and their EFs and thus may allow a greater survival of the parasites within these cells.
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Affiliation(s)
- J el-On
- Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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34
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Castanys S, Gamarro F, Ruiz-Pérez LM, Osuna A. Purification of a glycoprotein excreted by Trypanosoma cruzi to increase the permeability of the host-cell membrane. Biochem Biophys Res Commun 1990; 166:736-42. [PMID: 2405854 DOI: 10.1016/0006-291x(90)90871-j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During invasion of the prospective host cell, metacyclic forms of Trypanosoma cruzi render the membrane of HeLa cells permeable to the alpha-sarcin toxin, by excreting a glycoprotein with N-acetyl-D-glucosamine residues. The molecular weight of the glycoprotein is 64,000 dalton and its isoelectric point is 4.8.
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Affiliation(s)
- S Castanys
- Department of Parasitology, Faculty of Science, University of Granada, Spain
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35
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Jaffe CL, Pérez ML, Sarfstein R. Leishmania tropica: characterization of a lipophosphoglycan-like antigen recognized by species-specific monoclonal antibodies. Exp Parasitol 1990; 70:12-24. [PMID: 1688534 DOI: 10.1016/0014-4894(90)90081-m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Species-specific monoclonal antibodies to Leishmania tropica, T11 and T13-15, recognize membranal and secreted antigens. The membrane form of the antigen migrates on sodium dodecyl sulfate-polyacrylamide gels with a diffuse molecular weight from 15 to 50 kDa and can be labeled with palmitic acid, myoinositol, galactose, glucosamine, and inorganic phosphate. Both phosphate and sugar-labeled material were isolated from metabolically labeled promastigotes by affinity chromatography on antibodies coupled to Sepharose 4B. No binding to Ricinus communis agglutinin was observed. This material behaves like lipophosphoglycans from other Leishmania but contains unique species-specific epitopes. It is susceptible to cleavage by phospholipase C and after digestion no longer partitions into the detergent phase following a Triton X-114 extraction. All four monoclonal antibodies appear to recognize a carbohydrate epitope on the lipophosphoglycan since periodate treatment of this material bound to nitrocellulose essentially eliminated antibody binding. In addition, T15 binding could be blocked by 5 mM mannose-6-PO4 and fructose-1- or 6-PO4, but not by mannose, glucose, fructose, or the additional PO4 derivatives examined. The antibodies recognize a similar but not identical epitope, as demonstrated by a competitive radioimmunoassay using 125I-labeled T11, T13, and T15. Expression of surface antigen is elevated during the promastigote stationary phase.
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Affiliation(s)
- C L Jaffe
- Department of Biophysics, Weizmann Institute of Science, Rehovot, Israel
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36
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Mukherjee A, Seth M, Bhaduri AP. Present status of Leishmaniasis. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1990; 34:447-90. [PMID: 2236573 DOI: 10.1007/978-3-0348-7128-0_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- A Mukherjee
- Division of Medicinal Chemistry, Central Drug Research Institute, Lucknow, India
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37
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McNeely TB, Rosen G, Londner MV, Turco SJ. Inhibitory effects on protein kinase C activity by lipophosphoglycan fragments and glycosylphosphatidylinositol antigens of the protozoan parasite Leishmania. Biochem J 1989; 259:601-4. [PMID: 2524191 PMCID: PMC1138552 DOI: 10.1042/bj2590601] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fragments of the lipophosphoglycan of Leishmania donovani were generated by phospholipase C digestion and mild acid hydrolysis. The fragments were purified and examined for inhibitory activity on protein kinase C isolated from rat brains. On a molar basis, the 1-O-alkylglycerol portion of LPG exhibited the most inhibitory activity, whereas the carbohydrate domain was not as effective. In addition, several glycolipid antigens from L. major, which contain short carbohydrate chains attached to phosphatidylinositol, were also efficient inhibitors of the enzyme. These results are consistent with the hypothesis that protein kinase C may be a key target for the parasites to overcome within host macrophages.
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Affiliation(s)
- T B McNeely
- Department of Biochemistry, University of Kentucky Medical Center, Lexington 40502
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38
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Abstract
The major cell surface glycoconjugate of leishmanial parasites is lipophosphoglycan (LPG). Its relative abundance, unique structure, and cellular location suggest one or more important roles in interactions between parasites and host cells. In this article, Sam Turco examines current information about this novel glycoconjugate and its significance.
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Affiliation(s)
- S J Turco
- Department of Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA
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39
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Buchmüller-Rouiller Y, Mauël J. Impairment of the oxidative metabolism of mouse peritoneal macrophages by intracellular Leishmania spp. Infect Immun 1987; 55:587-93. [PMID: 3546131 PMCID: PMC260378 DOI: 10.1128/iai.55.3.587-593.1987] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
When stimulated in vitro with macrophage-activating factor or lipopolysaccharide, mouse peritoneal macrophages acquire the capacity to develop a strong respiratory burst when they are triggered by membrane-active agents. The presence of intracellular parasites of the genus Leishmania (L. enriettii, L. major) significantly inhibited such activity, as measured by chemiluminescence, reduction of cytochrome c and Nitro Blue Tetrazolium, and hexose monophosphate shunt levels. On the contrary, inert intracellular particles such as latex beads strongly increased the macrophage respiratory burst, suggesting that the Leishmania-linked inhibition resulted from a specific parasite effect. Impairment of macrophage oxidative metabolism by intracellular Leishmania spp. was a function of the number of infecting microorganisms and was more pronounced in macrophages infected with living than with dead parasites. Moreover, the metabolic inhibition was less apparent in L. enriettii-infected macrophages that were exposed to both macrophage-activating factor and lipopolysaccharide, i.e., conditions leading to complete parasite destruction. The mechanisms of respiratory burst inhibition by intracellular Leishmania spp. are unclear, but these observations suggest that such effects may contribute significantly to intracellular survival of the microorganisms.
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