51
|
Michailowsky V, Luhrs K, Rocha MOC, Fouts D, Gazzinelli RT, Manning JE. Humoral and cellular immune responses to Trypanosoma cruzi-derived paraflagellar rod proteins in patients with Chagas' disease. Infect Immun 2003; 71:3165-71. [PMID: 12761095 PMCID: PMC155720 DOI: 10.1128/iai.71.6.3165-3171.2003] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sera and peripheral blood mononuclear cells (PBMC) from patients displaying different clinical symptoms as well as from normal uninfected individuals (NI) were used to evaluate the humoral and cellular responses of Chagas' disease patients to Trypanosoma cruzi-derived paraflagellar rod proteins (PFR). Our results show that sera from both asymptomatic Chagas' disease patients (ACP) and cardiac Chagas' disease patients (CCP) have higher levels of antibodies to PFR than sera from NI. Immunoglobulin G1 (IgG1) and IgG3 were the main Ig isotypes that recognized PFR. We also tested three recombinant forms of PFR, named rPAR-1, rPAR-2, and rPAR-3, by Western blot analysis. Sera from seven out of eight patients with Chagas' disease recognized one of the three rPAR forms. Sera from 75, 50, and 37.5% of Chagas' disease patients tested recognized rPAR-3, rPAR-2, and rPAR-1, respectively. PFR induced proliferation of 100 and 70% of PBMC from ACP and CCP, respectively. Further, stimulation of cells from Chagas' disease patients with PFR enhanced the frequencies of both small and large CD4(+) CD25(+) and CD4(+) CD69(+) lymphocytes, as well as that of small CD8(+) CD25(+) lymphocytes. Finally, we evaluated the ability of PFR to elicit the production of gamma interferon (IFN-gamma) by PBMC from patients with Chagas' disease. Fifty percent of the PBMC from ACP as well as CCP produced IFN-gamma upon stimulation with PFR. PFR enhanced the percentages of IFN-gamma-producing cells in both CD3(+) and CD3(-) populations. Within the T-cell population, large CD4(+) T lymphocytes were the main source of IFN-gamma.
Collapse
Affiliation(s)
- Vladimir Michailowsky
- Laboratory of Immunopathology, René Rachou Research Center-Oswaldo Cruz Foundation, Minas Gerais, Brazil
| | | | | | | | | | | |
Collapse
|
52
|
Urbina JA, Concepcion JL, Montalvetti A, Rodriguez JB, Docampo R. Mechanism of action of 4-phenoxyphenoxyethyl thiocyanate (WC-9) against Trypanosoma cruzi, the causative agent of Chagas' disease. Antimicrob Agents Chemother 2003; 47:2047-50. [PMID: 12760897 PMCID: PMC155860 DOI: 10.1128/aac.47.6.2047-2050.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the molecular basis of the activity of 4-phenoxyphenoxyethyl thiocyanate (WC-9) against Trypanosoma cruzi, the etiological agent of Chagas' disease. We found that growth inhibition of T. cruzi epimastigotes induced by this compound was associated with a reduction in the content of the parasite's endogenous sterols due to a specific blockade of their de novo synthesis at the level of squalene synthase.
Collapse
Affiliation(s)
- Julio A Urbina
- Laboratorio de Quimica Biológica, Centro de Bioquimica y Biofisica, Instituto Venezolano de Investigaciones Cientificas, Carretera Panamericana, Caracas 1020, Venezuela.
| | | | | | | | | |
Collapse
|
53
|
Abstract
Reactive oxygen species are the unwanted by-products of aerobic metabolism. To protect cells against their potentially lethal effects a series of pathways have evolved that are collectively called the oxidative defence system. In most eukaryotes, catalases and selenium-dependent glutathione peroxidases form the front line of defence against hydroperoxide-mediated damage. However, these activities are lacking in members of the Trypanosomatidae family of protozoan parasites. Instead these organisms contain several enzyme-mediated pathways for removal of hydroperoxides that are centred upon the unusual thiol trypanothione. Here we discuss the biochemical properties of one group of these enzymes, the non-selenium glutathione-dependent peroxidases, and outline the roles that they play in protecting the parasite against hydroperoxides associated with biological membranes.
Collapse
Affiliation(s)
- Shane R Wilkinson
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | | |
Collapse
|
54
|
Araya JE, Neira I, da Silva S, Mortara RA, Manque P, Cordero E, Sagua H, Loyola A, Bórquez J, Morales G, González J. Diterpenoids from Azorella compacta (Umbelliferae) active on Trypanosoma cruzi. Mem Inst Oswaldo Cruz 2003; 98:413-8. [PMID: 12886426 DOI: 10.1590/s0074-02762003000300022] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The anti-Trypanosoma cruzi activity of natural products isolated from Azorella compacta was evaluated, with particular emphasis on their effect against intracellular amastigotes. Five diterpenoids from A. compacta derived from mulinane and azorellane were isolated and identified. Only two products, named azorellanol (Y-2) and mulin-11,3-dien-20-oic acid (Y-5), showed trypanocidal activity against all stages of T. cruzi including intracellular amastigotes. At 10 M, these compounds displayed a strong lytic activity. It ranged from 88.4 0.6 to 99.0 1 % for all strains and stages evaluate, with an IC50 /18 h values of 20-84 M and 41-87 M, respectively. The development of intracellular amastigotes was also inhibited by nearly 60% at 25 M. The trypanocidal molecules Y-2 and Y-5 did show different degrees of cytotoxicity depending on the cell line tested, with an IC50 /24 h ranging from 33.2 to 161.2 M. We evaluated the effect of diterpenoids against intracellular T. cruzi forms by immunofluorescent identification of a specific membrane molecular marker (Ssp-4 antigen) of the T. cruzi amastigote forms. The accuracy and reproducibility of the measurements were found to be outstanding when examined by confocal microscopy.
Collapse
Affiliation(s)
- Jorge E Araya
- Unidad de Parasitolog a, Departamento de Tecnolog a M dica, Universidad de Antofagasta
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
55
|
Affiliation(s)
- William Martin
- Institute of Botany III, Universität Düsseldorf, Universitätstrasse 1, D-40225 Düsseldorf, Germany.
| | | |
Collapse
|
56
|
Urbina JA, Payares G, Sanoja C, Molina J, Lira R, Brener Z, Romanha AJ. Parasitological cure of acute and chronic experimental Chagas disease using the long-acting experimental triazole TAK-187. Activity against drug-resistant Trypanosoma cruzi strains. Int J Antimicrob Agents 2003; 21:39-48. [PMID: 12507836 DOI: 10.1016/s0924-8579(02)00274-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We investigated the activity of TAK-187, an experimental antifungal triazole with a long terminal half-life in several experimental animals, against Trypanosoma cruzi. In vitro studies showed that the minimal inhibitory concentration (MIC) against the (extracellular) epimastigote form was 0.3-1 microM, while the corresponding concentration against clinically relevant intracellular amastigotes was 1 nM. At the MIC the endogenous epimastigote C4,14-desmethyl sterols were replaced by di- and tri-methylated sterols, supporting the notion that the primary target of TAK-187 is the parasite's sterol C14alpha demethylase. We investigated the in vivo activity of the compound in a murine model of acute Chagas disease, using T. cruzi strains with different susceptibilities to the drugs currently used clinically (nitrofurans and nitroimidazoles). It was found that TAK-187 given orally at 20 mg/kg induced complete protection against death and high levels (60-100%) of parasitological cures, independently of the infecting strain and even when administered every other day (e.o.d.), consistent with its long terminal half-life in mice. Other experiments, using longer treatment periods were carried out in both acute and chronic models of the disease and showed that TAK-187 given at 10-20 mg/kg e.o.d. induced 80-100% survival with 80-100% of parasitological cures of survivors in both models. No toxic side effects were observed in any of the experimental protocols. TAK-187 is a potent anti-T. cruzi compound with trypanocidal activity in vivo and should be considered for further studies as a potential specific treatment of human Chagas disease.
Collapse
Affiliation(s)
- Julio A Urbina
- Laboratorio de Química Biológica, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Apartado 21827, Caracas 1020A, Venezuela.
| | | | | | | | | | | | | |
Collapse
|
57
|
Urbina JA, Payares G, Sanoja C, Lira R, Romanha AJ. In vitro and in vivo activities of ravuconazole on Trypanosoma cruzi, the causative agent of Chagas disease. Int J Antimicrob Agents 2003; 21:27-38. [PMID: 12507835 DOI: 10.1016/s0924-8579(02)00273-x] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Ravuconazole is an experimental triazole derivative with potent and broad-spectrum antifungal activity and a remarkably long half-life in humans. In this work, we investigated the in vitro and in vivo activities of this compound against Trypanosoma cruzi. Ravuconazole showed very potent in vitro anti-T. cruzi activity with minimal inhibitory concentrations (MIC) of 300 and 1 nM against the extracellular epimastigote and intracellular amastigote forms, respectively. As with other azole derivatives, ravuconazole at the MIC led to an essentially complete depletion of the epimastigotes' endogenous C4,14-desmethyl sterols and their replacement by di- and tri-methylated sterols. In murine acute models of acute Chagas disease, it was found that ravuconazole treatment led to high levels of parasitological cures, but only when given twice a day (b.i.d.), consistent with its short terminal half-life in mice (4 h). Furthermore, it was found that this curative activity was restricted towards nitrofuran/nitroimidazole-susceptible (CL) and partially drug-resistant (Y) strains of T. cruzi, with no curative activity in animals infected with the fully drug-resistant Colombiana strain. No curative activity occurred in a chronic model of the disease. No toxic side effects were observed resulting from treatment with the triazole. Ravuconazole is a very potent and specific anti-T. cruzi agent in vitro but its in vivo activity in mice is limited, probably due to its unfavourable pharmacokinetic properties in this animal model. However, these results do not necessarily rule out the potential utility of ravuconazole in the treatment of human T. cruzi infections.
Collapse
Affiliation(s)
- Julio A Urbina
- Laboratorio de Química Biológica, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Apartado 21827, Caracas 1020A, Venezuela.
| | | | | | | | | |
Collapse
|
58
|
Toledo MJDO, Bahia MT, Carneiro CM, Martins-Filho OA, Tibayrenc M, Barnabé C, Tafuri WL, de Lana M. Chemotherapy with benznidazole and itraconazole for mice infected with different Trypanosoma cruzi clonal genotypes. Antimicrob Agents Chemother 2003; 47:223-30. [PMID: 12499195 PMCID: PMC149031 DOI: 10.1128/aac.47.1.223-230.2003] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The benznidazole (BZ) and itraconazole (ITC) susceptibilities of a standard set of Trypanosoma cruzi natural stocks were evaluated during the acute phase and the chronic phase of experimental chagasic infection in BALB/c mice. Twenty laboratory-cloned stocks representative of the total phylogenetic diversity of T. cruzi, including genotypes 20 and 19 (T. cruzi I) and genotypes 39 and 32 (T. cruzi II), were analyzed. Our results demonstrate important differences among stocks that could be pointed out as markers of biological behavior. Members of the T. cruzi I group were highly resistant to both BZ and ITC, whereas members of the T. cruzi II group were partially resistant to both drugs, despite their susceptibilities to ITC during the chronic phase of infection. The resistance to BZ observed for T. cruzi I was mainly triggered by genotype 20 isolates, whereas resistance to ITC was due to both genotype 20 and 19 isolates. Two polar patterns of response to BZ observed for genotype 39 isolates had a major impact on the partial resistance pattern observed for members of the T. cruzi II group. Genotype 32 isolates showed a typical profile of susceptibility. The correlation between the response to treatment and phylogenetic classification of T. cruzi stocks was clearer for ITC than for BZ. In conclusion, the data presented show a correlation between phylogenetic divergence among T. cruzi stocks and their susceptibilities to chemotherapeutic agents in vivo. Our results warn of the necessity to take into account the lesser genetic subdivisions of T. cruzi stocks since the upper subdivisions (T. cruzi I and II) show a great deal of heterogeneity for in vivo drug susceptibility.
Collapse
Affiliation(s)
- Max Jean de Ornelas Toledo
- Departamento Análises Clínicas, Centro de Ciências da Saúde, Universidade Estadual de Maringá, Maringá, Brazil.
| | | | | | | | | | | | | | | |
Collapse
|
59
|
Urbina JA, Concepcion JL, Rangel S, Visbal G, Lira R. Squalene synthase as a chemotherapeutic target in Trypanosoma cruzi and Leishmania mexicana. Mol Biochem Parasitol 2002; 125:35-45. [PMID: 12467972 DOI: 10.1016/s0166-6851(02)00206-2] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Trypanosoma cruzi and Leishmania parasites have a strict requirement for specific endogenous sterols (ergosterol and analogs) for survival and growth and cannot use the abundant supply of cholesterol present in their mammalian hosts. Squalene synthase (SQS, E.C. 2.5.1.21) catalyzes the first committed step in sterol biosynthesis and is currently under intense study as a possible target for cholesterol-lowering agents in humans, but it has not been investigated as a target for anti-parasitic chemotherapy. SQS is a membrane-bound enzyme in both T. cruzi epimastigotes and Leishmania mexicana promastigotes with a dual subcellular localization, being almost evenly distributed between glycosomes and mitochondrial/microsomal vesicles. Kinetic studies showed that the parasite enzymes display normal Michaelis-Menten kinetics and the values of the kinetic constants are comparable to those of the mammalian enzyme. We synthesized and purified 3-(biphenyl-4-yl)-3-hydroxyquinuclidine (BPQ-OH), a potent and specific inhibitor of mammalian SQS and found that it is also a powerful non-competitive inhibitor of T. cruzi and L. mexicana SQS, with K(i)'s in the range of 12-62 nM. BPQ-OH induced a dose-dependent reduction of proliferation the extracellular stages of these parasites with minimal growth inhibitory concentrations (MIC) of 10-30 microM. Growth inhibition and cell lysis induced by BPQ-OH in both parasites was associated with complete depletion of endogenous squalene and sterols, consistent with a blockade of de novo sterol synthesis at the level of SQS. BPQ-OH was able to eradicate intracellular T. cruzi amastigotes from Vero cells cultured at 37 degrees C, with a MIC of 30 microM with no deleterious effects on host cells. Taken together, these results support the notion that SQS inhibitors could be developed as selective anti-trypanosomatid agents.
Collapse
Affiliation(s)
- Julio A Urbina
- Laboratorio de Quimica Biológica, Centro de Bioquimica y Biofisica, Instituto Venezolano de Investigaciones Cientificas, Caracas 1020, Venezuela.
| | | | | | | | | |
Collapse
|
60
|
Abstract
The protozoan parasite Trypanosoma cruzi is responsible for Chagas disease, a serious debilitating disease that affects millions of people in Latin America. Trypomastigotes, the infective forms, are capable of invading and replicating in different cell types. The invasion process involves a gradual recruitment and fusion of host cell lysosomes at the parasite entry site, and is regulated by intracellular free Ca2+ transients triggered by trypomastigotes in host cells. This unusual, Ca2+-dependent lysosome exocytosis pathway was recently shown to be involved in the mechanism by which mammalian cells repair lesions on their plasma membrane.
Collapse
Affiliation(s)
- Henry Tan
- Section of Microbial Pathogenesis and Dept of Cell Biology, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | | |
Collapse
|
61
|
Affiliation(s)
- Michael H Gelb
- Departments of Chemistry, University of Washington, Seattle, WA 98195, USA
| | | |
Collapse
|