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1.
Nat Commun ; 15(1): 4400, 2024 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-38782898

RESUMEN

Digestive Chagas disease (DCD) is an enteric neuropathy caused by Trypanosoma cruzi infection. There is a lack of evidence on the mechanism of pathogenesis and rationales for treatment. We used a female C3H/HeN mouse model that recapitulates key clinical manifestations to study how infection dynamics shape DCD pathology and the impact of treatment with the front-line, anti-parasitic drug benznidazole. Curative treatment 6 weeks post-infection resulted in sustained recovery of gastrointestinal transit function, whereas treatment failure led to infection relapse and gradual return of DCD symptoms. Neuro/immune gene expression patterns shifted from chronic inflammation to a tissue repair profile after cure, accompanied by increased cellular proliferation, glial cell marker expression and recovery of neuronal density in the myenteric plexus. Delaying treatment until 24 weeks post-infection led to partial reversal of DCD, suggesting the accumulation of permanent tissue damage over the course of chronic infection. Our study shows that murine DCD pathogenesis is sustained by chronic T. cruzi infection and is not an inevitable consequence of acute stage denervation. The risk of irreversible enteric neuromuscular tissue damage and dysfunction developing highlights the importance of prompt diagnosis and treatment. These findings support the concept of treating asymptomatic, T. cruzi-infected individuals with benznidazole to prevent DCD development.


Asunto(s)
Enfermedad de Chagas , Modelos Animales de Enfermedad , Sistema Nervioso Entérico , Ratones Endogámicos C3H , Nitroimidazoles , Tripanocidas , Trypanosoma cruzi , Animales , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/parasitología , Femenino , Tripanocidas/farmacología , Tripanocidas/uso terapéutico , Nitroimidazoles/farmacología , Nitroimidazoles/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Ratones , Sistema Nervioso Entérico/efectos de los fármacos , Regeneración Nerviosa/efectos de los fármacos
2.
PLoS Negl Trop Dis ; 18(5): e0012106, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38820564

RESUMEN

Chagas disease is caused by Trypanosoma cruzi, a protozoan parasite that displays considerable genetic diversity. Infections result in a range of pathological outcomes, and different strains can exhibit a wide spectrum of anti-parasitic drug tolerance. The genetic determinants of infectivity, virulence and therapeutic susceptibility remain largely unknown. As experimental tools to address these issues, we have generated a panel of bioluminescent:fluorescent parasite strains that cover the diversity of the T. cruzi species. These reporters allow spatio-temporal infection dynamics in murine models to be monitored in a non-invasive manner by in vivo imaging, provide a capability to detect rare infection foci at single-cell resolution, and represent a valuable resource for investigating virulence and host:parasite interactions at a mechanistic level. Importantly, these parasite reporter strains can also contribute to the Chagas disease drug screening cascade by ensuring that candidate compounds have pan-species in vivo activity prior to being advanced into clinical testing. The parasite strains described in this paper are available on request.


Asunto(s)
Enfermedad de Chagas , Trypanosoma cruzi , Trypanosoma cruzi/genética , Trypanosoma cruzi/efectos de los fármacos , Enfermedad de Chagas/parasitología , Animales , Ratones , Genotipo , Modelos Animales de Enfermedad , Variación Genética , Fenotipo , Mediciones Luminiscentes/métodos , Genes Reporteros , Humanos , Femenino , Interacciones Huésped-Parásitos
3.
Sci Transl Med ; 15(726): eadg8105, 2023 12 13.
Artículo en Inglés | MEDLINE | ID: mdl-38091410

RESUMEN

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects millions of people in the Americas and across the world, leading to considerable morbidity and mortality. Current treatment options, benznidazole (BNZ) and nifurtimox, offer limited efficacy and often lead to adverse side effects because of long treatment durations. Better treatment options are therefore urgently required. Here, we describe a pyrrolopyrimidine series, identified through phenotypic screening, that offers an opportunity to improve on current treatments. In vitro cell-based washout assays demonstrate that compounds in the series are incapable of killing all parasites; however, combining these pyrrolopyrimidines with a subefficacious dose of BNZ can clear all parasites in vitro after 5 days. These findings were replicated in a clinically predictive in vivo model of chronic Chagas disease, where 5 days of treatment with the combination was sufficient to prevent parasite relapse. Comprehensive mechanism of action studies, supported by ligand-structure modeling, show that compounds from this pyrrolopyrimidine series inhibit the Qi active site of T. cruzi cytochrome b, part of the cytochrome bc1 complex of the electron transport chain. Knowledge of the molecular target enabled a cascade of assays to be assembled to evaluate selectivity over the human cytochrome b homolog. As a result, a highly selective and efficacious lead compound was identified. The combination of our lead compound with BNZ rapidly clears T. cruzi parasites, both in vitro and in vivo, and shows great potential to overcome key issues associated with currently available treatments.


Asunto(s)
Enfermedad de Chagas , Parásitos , Tripanocidas , Trypanosoma cruzi , Animales , Humanos , Citocromos b , Tripanocidas/efectos adversos , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/inducido químicamente , Enfermedad de Chagas/parasitología
4.
Pathogens ; 12(11)2023 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-38003828

RESUMEN

Chronic Chagas cardiomyopathy (CCC) results from infection with the protozoan parasite Trypanosoma cruzi and is a prevalent cause of heart disease in endemic countries. We previously found that cardiac fibrosis can vary widely in C3H/HeN mice chronically infected with T. cruzi JR strain, mirroring the spectrum of heart disease in humans. In this study, we examined functional cardiac abnormalities in this host:parasite combination to determine its potential as an experimental model for CCC. We utilised electrocardiography (ECG) to monitor T. cruzi-infected mice and determine whether ECG markers could be correlated with cardiac function abnormalities. We found that the C3H/HeN:JR combination frequently displayed early onset CCC indicators, such as sinus bradycardia and right bundle branch block, as well as prolonged PQ, PR, RR, ST, and QT intervals in the acute stage. Our model exhibited high levels of cardiac inflammation and enhanced iNOS expression in the acute stage, but denervation did not appear to have a role in pathology. These results demonstrate the potential of the C3H/HeN:JR host:parasite combination as a model for CCC that could be used for screening new compounds targeted at cardiac remodelling and for examining the potential of antiparasitic drugs to prevent or alleviate CCC development and progression.

5.
J Med Chem ; 66(18): 13043-13057, 2023 09 28.
Artículo en Inglés | MEDLINE | ID: mdl-37722077

RESUMEN

We designed and synthesized a series of symmetric bis-6-amidino-benzothiazole derivatives with aliphatic central units and evaluated their efficacy against bloodstream forms of the African trypanosome Trypanosoma brucei. Of these, a dicationic benzothiazole compound (9a) exhibited sub-nanomolar in vitro potency with remarkable selectivity over mammalian cells (>26,000-fold). Unsubstituted 5-amidine groups and a cyclohexyl spacer were the crucial determinants of trypanocidal activity. In all cases, mice treated with a single dose of 20 mg kg-1 were cured of stage 1 trypanosomiasis. The compound displayed a favorable in vitro ADME profile, with the exception of low membrane permeability. However, we found evidence that uptake by T. brucei is mediated by endocytosis, a process that results in lysosomal sequestration. The compound was also active in low nanomolar concentrations against cultured asexual forms of the malaria parasite Plasmodium falciparum. Therefore, 9a has exquisite cross-species efficacy and represents a lead compound with considerable therapeutic potential.


Asunto(s)
Tripanocidas , Trypanosoma brucei brucei , Trypanosoma , Tripanosomiasis Africana , Tripanosomiasis , Ratones , Animales , Tripanosomiasis Africana/tratamiento farmacológico , Tripanosomiasis Africana/parasitología , Tripanosomiasis/tratamiento farmacológico , Benzotiazoles/farmacología , Benzotiazoles/uso terapéutico , Tripanocidas/farmacología , Tripanocidas/uso terapéutico , Mamíferos
6.
Science ; 380(6652): 1349-1356, 2023 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-37384702

RESUMEN

Millions who live in Latin America and sub-Saharan Africa are at risk of trypanosomatid infections, which cause Chagas disease and human African trypanosomiasis (HAT). Improved HAT treatments are available, but Chagas disease therapies rely on two nitroheterocycles, which suffer from lengthy drug regimens and safety concerns that cause frequent treatment discontinuation. We performed phenotypic screening against trypanosomes and identified a class of cyanotriazoles (CTs) with potent trypanocidal activity both in vitro and in mouse models of Chagas disease and HAT. Cryo-electron microscopy approaches confirmed that CT compounds acted through selective, irreversible inhibition of trypanosomal topoisomerase II by stabilizing double-stranded DNA:enzyme cleavage complexes. These findings suggest a potential approach toward successful therapeutics for the treatment of Chagas disease.


Asunto(s)
Enfermedad de Chagas , Inhibidores de Topoisomerasa II , Triazoles , Trypanosoma , Tripanosomiasis Africana , Animales , Humanos , Ratones , Enfermedad de Chagas/tratamiento farmacológico , Microscopía por Crioelectrón , ADN-Topoisomerasas de Tipo II/metabolismo , Trypanosoma/efectos de los fármacos , Inhibidores de Topoisomerasa II/química , Inhibidores de Topoisomerasa II/farmacología , Inhibidores de Topoisomerasa II/uso terapéutico , Triazoles/química , Triazoles/farmacología , Triazoles/uso terapéutico , Tripanosomiasis Africana/tratamiento farmacológico , Evaluación Preclínica de Medicamentos
7.
PLoS Negl Trop Dis ; 16(10): e0010827, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36190992

RESUMEN

BACKGROUND: Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and is a serious public health problem throughout Latin America. With 6 million people infected, there is a major international effort to develop new drugs. In the chronic phase of the disease, the parasite burden is extremely low, infections are highly focal at a tissue/organ level, and bloodstream parasites are only intermittently detectable. As a result, clinical trials are constrained by difficulties associated with determining parasitological cure. Even highly sensitive PCR methodologies can be unreliable, with a tendency to produce "false-cure" readouts. Improved diagnostic techniques and biomarkers for cure are therefore an important medical need. METHODOLOGY/PRINCIPAL FINDINGS: Using an experimental mouse model, we have combined a multiplex assay system and highly sensitive bioluminescence imaging to evaluate serological procedures for diagnosis of T. cruzi infections and confirmation of parasitological cure. We identified a set of three antigens that in the context of the multiplex serology system, provide a rapid, reactive and highly accurate read-out of both acute and chronic T. cruzi infection. In addition, we describe specific antibody responses where down-regulation can be correlated with benznidazole-mediated parasite reduction and others where upregulation is associated with persistent infection. One specific antibody (IBAG39) highly correlated with the bioluminescence flux and represents a promising therapy monitoring biomarker in mice. CONCLUSIONS/SIGNIFICANCE: Robust, high-throughput methodologies for monitoring the efficacy of anti-T. cruzi drug treatment are urgently required. Using our experimental systems, we have identified markers of infection or parasite reduction that merit assessing in a clinical setting for the longitudinal monitoring of drug-treated patients.


Asunto(s)
Enfermedad de Chagas , Trypanosoma cruzi , Animales , Biomarcadores , Enfermedad de Chagas/diagnóstico , Enfermedad de Chagas/tratamiento farmacológico , Inmunoensayo/métodos , Pruebas Inmunológicas , Ratones
8.
PLoS Pathog ; 16(4): e1008456, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32282850

RESUMEN

Leishmania donovani causes visceral leishmaniasis (VL), which is typically fatal without treatment. There is substantial variation between individuals in rates of disease progression, response to treatment and incidence of post-treatment sequelae, specifically post-kala-azar dermal leishmaniasis (PKDL). Nevertheless, the majority of infected people are asymptomatic carriers. Hamsters and mice are commonly used as models of fatal and non-fatal VL, respectively. Host and parasite genetics are likely to be important factors, but in general the reasons for heterogeneous disease presentation in humans and animal models are poorly understood. Host microbiota has become established as a factor in cutaneous forms of leishmaniasis but this has not been studied in VL. We induced intestinal dysbiosis in mice and hamsters by long-term treatment with broad-spectrum antibiotics in their drinking water. There were no significant differences in disease presentation in dysbiotic mice. In contrast, dysbiotic hamsters infected with L. donovani had delayed onset and progression of weight loss. Half of control hamsters had a rapid progression phenotype compared with none of the ABX-treated animals and the nine-month survival rate was significantly improved compared to untreated controls (40% vs. 10%). Antibiotic-treated hamsters also had significantly less severe hepatosplenomegaly, which was accompanied by a distinct cytokine gene expression profile. The protective effect was not explained by differences in parasite loads or haematological profiles. We further found evidence that the gut-liver axis is a key aspect of fatal VL progression in hamsters, including intestinal parasitism, bacterial translocation to the liver, malakoplakia and iron sequestration, none of which occurred in non-progressing murine VL. Diverse bacterial genera were cultured from VL affected livers, of which Rodentibacter was specifically absent from ABX-treated hamsters, indicating this pathobiont may play a role in promoting disease progression. The results provide experimental support for antibiotic prophylaxis against secondary bacterial infections as an adjunct therapy in human VL patients.


Asunto(s)
Antibacterianos/administración & dosificación , Infecciones Bacterianas/prevención & control , Coinfección/prevención & control , Parasitosis Intestinales/parasitología , Leishmaniasis Visceral/parasitología , Animales , Profilaxis Antibiótica , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Fenómenos Fisiológicos Bacterianos , Coinfección/microbiología , Cricetinae , Progresión de la Enfermedad , Femenino , Microbioma Gastrointestinal , Humanos , Leishmania donovani/fisiología , Leishmaniasis Visceral/complicaciones , Masculino , Mesocricetus , Ratones , Ratones Endogámicos C57BL , Simbiosis
9.
Microb Pathog ; 137: 103711, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31491548

RESUMEN

Chagas disease affects millions of people, and it is a major cause of death in Latin America. Prevention and development of an effective treatment for this infection can be favored by a more thorough understanding of T. cruzi interaction with the microbiome of vectors and hosts. Next-generation sequencing technology vastly broadened the knowledge about intestinal bacteria composition, showing that microbiota within each host (triatomines and mammals) is composed by high diversity of species, although few dominant phyla. This fact may represent an ecological balance that was acquired during the evolutionary process of the microbiome-host complex, and that serves to perpetuate this system. In this context, commensal microbiota is also essential to protect hosts, conferring them resistance to pathogens colonization. However, in some situations, the microbiota is not able to prevent infection but only modulate it. Here we will review the role of the microbiota on the parasite-vector-host triad with a focus on the kinetoplastida of medical importance Trypanosoma cruzi. Novel strategies to control Chagas disease based on intestinal microbiome will also be discussed.


Asunto(s)
Enfermedad de Chagas/microbiología , Microbioma Gastrointestinal/fisiología , Insectos Vectores/microbiología , Animales , Evolución Biológica , Disbiosis/microbiología , Disbiosis/parasitología , Ecología , Interacciones Microbiota-Huesped/inmunología , Interacciones Huésped-Patógeno/inmunología , Humanos , Trypanosoma cruzi
10.
Artículo en Inglés | MEDLINE | ID: mdl-30082291

RESUMEN

Chagasic heart disease develops in 30% of those infected with the protozoan parasite Trypanosoma cruzi, but can take decades to become symptomatic. Because of this, it has been difficult to assess the extent to which antiparasitic therapy can prevent the development of pathology. We sought to address this question using experimental murine models, exploiting highly sensitive bioluminescent imaging to monitor curative efficacy. Mice were inoculated with bioluminescent parasites and then cured in either the acute or chronic stage of infection with benznidazole. At the experimental endpoint (5 to 6 months postinfection), heart tissue was removed and assessed for inflammation and fibrosis, two widely used markers of cardiac pathology. Infection of BALB/c and C3H/HeN mice with distinct T. cruzi lineages resulted in greatly increased myocardial collagen content at a group level, indicative of fibrotic pathology. When mice were cured by benznidazole in the acute stage, the development of pathology was completely blocked. However, if treatment was delayed until the chronic stage, cardiac fibrosis was observed in the BALB/c model, although the protective effect was maintained in the case of C3H/HeN mice. These experiments therefore demonstrate that curative benznidazole treatment early in murine T. cruzi infections can prevent the development of cardiac fibrosis. They also show that treatment during the chronic stage can block pathology but the effectiveness varies between infection models. If these findings are extendable to humans, it implies that widespread chemotherapeutic intervention targeted at early-stage infections could play a crucial role in reducing Chagas disease morbidity at a population level.


Asunto(s)
Enfermedad de Chagas/tratamiento farmacológico , Nitroimidazoles/uso terapéutico , Tripanocidas/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Trypanosoma cruzi/patogenicidad , Animales , Cardiomiopatía Chagásica/tratamiento farmacológico , Modelos Animales de Enfermedad , Femenino , Corazón/parasitología , Inflamación/tratamiento farmacológico , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Miocardio/patología
11.
PLoS Negl Trop Dis ; 12(4): e0006388, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29608569

RESUMEN

BACKGROUND: Infection with Trypanosoma cruzi causes Chagas disease, a major public health problem throughout Latin America. There is no vaccine and the only drugs have severe side effects. Efforts to generate new therapies are hampered by limitations in our understanding of parasite biology and disease pathogenesis. Studies are compromised by the complexity of the disease, the long-term nature of the infection, and the fact that parasites are barely detectable during the chronic stage. In addition, functional dissection of T. cruzi biology has been restricted by the limited flexibility of the genetic manipulation technology applicable to this parasite. METHODOLOGY/PRINCIPAL FINDINGS: Here, we describe two technical innovations, which will allow the role of the parasite in disease progression to be better assessed. First, we generated a T. cruzi reporter strain that expresses a fusion protein comprising red-shifted luciferase and green fluorescent protein domains. Bioluminescence allows the kinetics of infection to be followed within a single animal, and specific foci of infection to be pinpointed in excised tissues. Fluorescence can then be used to visualise individual parasites in tissue sections to study host-parasite interactions at a cellular level. Using this strategy, we have been routinely able to find individual parasites within chronically infected murine tissues for the first time. The second advance is the incorporation of a streamlined CRISPR/Cas9 functionality into this reporter strain that can facilitate genome editing using a PCR-based approach that does not require DNA cloning. This system allows the rapid generation of null mutants and fluorescently tagged parasites in a background where the in vivo phenotype can be rapidly assessed. CONCLUSIONS/SIGNIFICANCE: The techniques described here will have multiple applications for studying aspects of T. cruzi biology and Chagas disease pathogenesis previously inaccessible to conventional approaches. The reagents and cell lines have been generated as a community resource and are freely available on request.


Asunto(s)
Sistemas CRISPR-Cas , Enfermedad de Chagas/parasitología , Mediciones Luminiscentes/métodos , Trypanosoma cruzi/química , Trypanosoma cruzi/genética , Animales , Enfermedad de Chagas/diagnóstico , Femenino , Fluorescencia , Genes Reporteros , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Ratones , Ratones Endogámicos BALB C , Fenotipo , Trypanosoma cruzi/aislamiento & purificación , Trypanosoma cruzi/fisiología
12.
Sci Rep ; 6: 35351, 2016 10 17.
Artículo en Inglés | MEDLINE | ID: mdl-27748443

RESUMEN

The insect-transmitted protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, and infects 5-8 million people in Latin America. Chagas disease is characterised by an acute phase, which is partially resolved by the immune system, but then develops as a chronic life-long infection. There is a consensus that the front-line drugs benznidazole and nifurtimox are more effective against the acute stage in both clinical and experimental settings. However, confirmative studies have been restricted by difficulties in demonstrating sterile parasitological cure. Here, we describe a systematic study of nitroheterocyclic drug efficacy using highly sensitive bioluminescence imaging of murine infections. Unexpectedly, we find both drugs are more effective at curing chronic infections, judged by treatment duration and therapeutic dose. This was not associated with factors that differentially influence plasma drug concentrations in the two disease stages. We also observed that fexinidazole and fexinidazole sulfone are more effective than benznidazole and nifurtimox as curative treatments, particularly for acute stage infections, most likely as a result of the higher and more prolonged exposure of the sulfone derivative. If these findings are translatable to human patients, they will have important implications for treatment strategies.


Asunto(s)
Enfermedad de Chagas/tratamiento farmacológico , Nitroimidazoles/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Área Bajo la Curva , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Nifurtimox/farmacocinética , Nifurtimox/farmacología , Nitroimidazoles/farmacocinética , Resultado del Tratamiento , Tripanocidas/farmacocinética
13.
Angew Chem Int Ed Engl ; 55(31): 8994-8, 2016 07 25.
Artículo en Inglés | MEDLINE | ID: mdl-27314630

RESUMEN

Trimethylsilyl chloride is an efficient activating agent for azines in isocyanide-based reactions, which then proceed through a key insertion of the isocyanide into a N-Si bond. The reaction is initiated by N activation of the azine, followed by nucleophilic attack of an isocyanide in a Reissert-type process. Finally, a second equivalent of the same or a different isocyanide inserts into the N-Si bond leading to the final adduct. The use of distinct nucleophiles leads to a variety of α-substituted dihydroazines after a selective cascade process. Based on computational studies, a mechanistic hypothesis for the course of these reactions was proposed. The resulting products exhibit significant activity against Trypanosoma brucei and T. cruzi, featuring favorable drug-like properties and safety profiles.


Asunto(s)
Antiparasitarios/farmacología , Cianuros/química , Hidrazinas/química , Nitrógeno/química , Silicio/química , Trypanosoma cruzi/efectos de los fármacos , Antiparasitarios/síntesis química , Antiparasitarios/química , Estructura Molecular , Pruebas de Sensibilidad Parasitaria
14.
Cell Microbiol ; 18(10): 1429-43, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-26918803

RESUMEN

Host and parasite diversity are suspected to be key factors in Chagas disease pathogenesis. Experimental investigation of underlying mechanisms is hampered by a lack of tools to detect scarce, pleiotropic infection foci. We developed sensitive imaging models to track Trypanosoma cruzi infection dynamics and quantify tissue-specific parasite loads, with minimal sampling bias. We used this technology to investigate cardiomyopathy caused by highly divergent parasite strains in BALB/c, C3H/HeN and C57BL/6 mice. The gastrointestinal tract was unexpectedly found to be the primary site of chronic infection in all models. Immunosuppression induced expansion of parasite loads in the gut and was followed by widespread dissemination. These data indicate that differential immune control of T. cruzi occurs between tissues and shows that the large intestine and stomach provide permissive niches for active infection. The end-point frequency of heart-specific infections ranged from 0% in TcVI-CLBR-infected C57BL/6 to 88% in TcI-JR-infected C3H/HeN mice. Nevertheless, infection led to fibrotic cardiac pathology in all models. Heart disease severity was associated with the model-dependent frequency of dissemination outside the gut and inferred cumulative heart-specific parasite loads. We propose a model of cardiac pathogenesis driven by periodic trafficking of parasites into the heart, occurring at a frequency determined by host and parasite genetics.


Asunto(s)
Cardiomiopatías/parasitología , Enfermedad de Chagas/parasitología , Trypanosoma cruzi/genética , AMP Desaminasa , Animales , Cardiomiopatías/genética , Enfermedad de Chagas/genética , Femenino , Tracto Gastrointestinal/parasitología , Genes Protozoarios , Variación Genética , Interacciones Huésped-Parásitos , Masculino , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones SCID , Miocardio/patología
16.
Antimicrob Agents Chemother ; 59(8): 4653-61, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26014936

RESUMEN

The antifungal drug posaconazole has shown significant activity against Trypanosoma cruzi in vitro and in experimental murine models. Despite this, in a recent clinical trial it displayed limited curative potential. Drug testing is problematic in experimental Chagas disease because of difficulties in demonstrating sterile cure, particularly during the chronic stage of infection when parasite burden is extremely low and tissue distribution is ill defined. To better assess posaconazole efficacy against acute and chronic Chagas disease, we have exploited a highly sensitive bioluminescence imaging system which generates data with greater accuracy than other methods, including PCR-based approaches. Mice inoculated with bioluminescent T. cruzi were assessed by in vivo and ex vivo imaging, with cyclophosphamide-induced immunosuppression used to enhance the detection of relapse. Posaconazole was found to be significantly inferior to benznidazole as a treatment for both acute and chronic T. cruzi infections. Whereas 20 days treatment with benznidazole was 100% successful in achieving sterile cure, posaconazole failed in almost all cases. Treatment of chronic infections with posaconazole did however significantly reduce infection-induced splenomegaly, even in the absence of parasitological cure. The imaging-based screening system also revealed that adipose tissue is a major site of recrudescence in mice treated with posaconazole in the acute, but not the chronic stage of infection. This in vivo screening model for Chagas disease is predictive, reproducible and adaptable to diverse treatment schedules. It should provide greater assurance that drugs are not advanced prematurely into clinical trial.


Asunto(s)
Antifúngicos/farmacología , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad Crónica/tratamiento farmacológico , Triazoles/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Enfermedad de Chagas/parasitología , Modelos Animales de Enfermedad , Femenino , Ratones , Ratones Endogámicos BALB C , Ratones SCID , Nitroimidazoles/farmacología
17.
J Biomol Screen ; 20(1): 36-43, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25296657

RESUMEN

The protozoan Trypanosoma cruzi is the causative agent of Chagas disease, one of the world's major neglected infections. Although development of improved antiparasitic drugs is considered a priority, there have been no significant treatment advances in the past 40 years. Factors that have limited progress include an incomplete understanding of pathogenesis, tissue tropism, and disease progression. In addition, in vivo models, which allow parasite burdens to be tracked throughout the chronic stage of infection, have been lacking. To address these issues, we have developed a highly sensitive in vivo imaging system based on bioluminescent T. cruzi, which express a red-shifted luciferase that emits light in the tissue-penetrating orange-red region of the spectrum. The exquisite sensitivity of this noninvasive murine model has been exploited to monitor parasite burden in real time throughout the chronic stage, has allowed the identification of the gastrointestinal tract as the major niche of long-term infection, and has demonstrated that chagasic heart disease can develop in the absence of locally persistent parasites. Here, we review the parameters of the imaging system and describe how this experimental model can be incorporated into drug development programs as a valuable tool for assessing efficacy against both acute and chronic T. cruzi infections.


Asunto(s)
Enfermedad de Chagas/diagnóstico , Enfermedad de Chagas/tratamiento farmacológico , Diagnóstico por Imagen , Tripanocidas/farmacología , Tripanocidas/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Animales , Enfermedad de Chagas/parasitología , Diagnóstico por Imagen/métodos , Diagnóstico por Imagen/normas , Modelos Animales de Enfermedad , Humanos , Ratones , Resultado del Tratamiento
18.
Vet Parasitol ; 205(3-4): 472-82, 2014 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-25234767

RESUMEN

Visceral leishmaniasis has a great impact on public health, and dogs are considered the main domestic reservoir of Leishmania infantum, the causal parasite. In this study, 159 animals naturally infected by L. infantum from an endemic area of Brazil were evaluated through an analysis of cellular responses, using flow cytometry, and of the hematological parameters. The results confirmed that disease progression is associated with anemia and reductions in eosinophils, monocytes and lymphocytes. The investigation of the immune response, based on the immunophenotypic profile of peripheral blood, showed declines in the absolute numbers of T lymphocytes CD5(+) and their subsets (CD4(+) and CD8(+)) and a drop of B lymphocytes in asymptomatic seropositive (AD-II) and symptomatic seropositive (SD) dogs. Neutrophils, when stimulated with soluble antigen of L. infantum, showed higher synthesis of interferon (IFN)-γ(+) in AD-II and SD groups, with decreased production of interleukin (IL)-4(+) in asymptomatic seronegative dogs positive for L. infantum infection based on polymerase chain reaction testing (AD-I group). In the AD-II and SD groups, subpopulations of stimulated lymphocytes (CD4(+) and CD8(+)) also exhibited greater synthesis of IFN-γ(+) and IL-4(+) in culture. These results suggest that the animals of the AD-II and SD groups exhibited a mixed immune response (Type 1 and 2) and the AD-I group presenting an immune profile very similar to normal control animals.


Asunto(s)
Anticuerpos Antiprotozoarios/sangre , Enfermedades de los Perros/parasitología , Leishmania infantum/inmunología , Leishmaniasis Visceral/veterinaria , Animales , Biomarcadores/metabolismo , Brasil/epidemiología , Resistencia a la Enfermedad , Susceptibilidad a Enfermedades , Perros , Eosinófilos/inmunología , Femenino , Citometría de Flujo/veterinaria , Leishmaniasis Visceral/parasitología , Masculino , Monocitos/inmunología , Linfocitos T/inmunología
19.
PLoS One ; 7(3): e32912, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22412949

RESUMEN

Although metacyclic and blood trypomastigotes are completely functional in relation to parasite-host interaction and/or target cell invasion, they differ in the molecules present on the surface. Thus, aspects related to the variability that the forms of T. cruzi interacts with host cells may lead to fundamental implications on the immune response against this parasite and, consequently, the clinical evolution of Chagas disease. We have shown that BT infected mice presented higher levels of parasitemia during all the acute phase of infection. Moreover, the infection with either MT or BT forms resulted in increased levels of total leukocytes, monocytes and lymphocytes, specifically later for MT and earlier for BT. The infection with BT forms presented earlier production of proinflammatory cytokine TNF-α and later of IFN-γ by both T cells subpopulations. This event was accompanied by an early cardiac inflammation with an exacerbation of this process at the end of the acute phase. On the other hand, infection with MT forms result in an early production of IFN-γ, with subsequent control in the production of this cytokine by IL-10, which provided to these animals an immunomodulatory profile in the end of the acute phase. These results are in agreement with what was found for cardiac inflammation where animals infected with MT forms showed intense cardiac inflammation later at infection, with a decrease in the same at the end of this phase. In summary, our findings emphasize the importance of taking into account the inoculums source of T. cruzi, since vectorial or transfusional routes of T. cruzi infection may trigger distinct parasite-host interactions during the acute phase that may influence relevant biological aspects of chronic Chagas disease.


Asunto(s)
Enfermedad de Chagas/inmunología , Enfermedad de Chagas/parasitología , Trypanosoma cruzi/inmunología , Animales , Citocinas/inmunología , Citocinas/metabolismo , Modelos Animales de Enfermedad , Femenino , Interacciones Huésped-Parásitos/inmunología , Inmunofenotipificación , Leucocitos/inmunología , Ratones , Miocarditis/inmunología , Miocarditis/parasitología , Miocarditis/patología , Parasitemia/inmunología , Bazo/inmunología , Linfocitos T/inmunología , Linfocitos T/metabolismo , Factores de Tiempo
20.
Exp Parasitol ; 128(4): 401-8, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21620835

RESUMEN

Desferrioxamine (DFO) is a potent iron chelator that is also known to modulate inflammation and act as an efficient antioxidant under normal conditions and under oxidative stress. Many in vitro and in vivo studies have shown the efficacy of DFO in the treatment of viral, bacterial and protozoan infections. DFO is known to reduce the intensity of Trypanosoma cruzi infections in mice even during a course of therapy that is not effective in maintaining anaemia or low iron levels. To further clarify these findings, we investigated the action of DFO on mouse T. cruzi infection outcomes and the direct impact of DFO on parasites. Infected animals treated with DFO (5 mg/animal/day) for 35 days, beginning 14 days prior to infection, presented lower parasitemia and lower cumulative mortality rate. No significant effect was observed on iron metabolism markers, erythrograms, leukograms or lymphocyte subsets. In the rapid method for testing in vivo T. cruzi susceptibility, DFO also induced lower parasitemia. In regard to its direct impact on parasites, DFO slightly inhibited the growth of amastigotes and trypomastigotes in fibroblast culture. Trypan blue staining showed no effects of DFO on parasite viability, and only minor apoptosis in trypomastigotes was observed. Nevertheless, a clear decrease in parasite mobility was detected. In conclusion, the beneficial actions of DFO on mice T. cruzi infection seem to be independent of host iron metabolism and free of significant haematological side effects. Through direct action on the parasite, DFO has more effective trypanostatic than trypanocidal properties.


Asunto(s)
Enfermedad de Chagas/tratamiento farmacológico , Deferoxamina/uso terapéutico , Parasitemia/tratamiento farmacológico , Tripanocidas/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Animales , Células Sanguíneas/efectos de los fármacos , Enfermedad de Chagas/mortalidad , Deferoxamina/farmacología , Ferritinas/sangre , Hierro/sangre , Masculino , Ratones , Parasitemia/mortalidad , Sideróforos/farmacología , Sideróforos/uso terapéutico , Tripanocidas/farmacología
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