Synthesis of new trypanocidal agents from the hybridisation of metronidazole and eugenol analogues

Nitroimidazole compounds are well-known bioactive substances, and the structural activity relationship has been reported whereby the position of the nitro group within the imidazole ring has a large influence on the activity. This study focuses on synthesising new trypanocidal agents from the hybridisation of metronidazole with different natural phenols (eugenol, dihydroeugenol and guaiacol). Two different coupling methodologies have been explored in order to analyse the influence of the connector on bioactivity: i) classic direct esterification (AD compounds) and ii) "click" chemistry using a triazole connector (AC compounds). The in vitro trypanocidal tests show good results for both AC and AD hybrid compounds against both epimastigote and trypomastigote forms of T. cruzi. In silico studies showed positive data for most of the synthesised compounds and, in general present low toxicological risks. The AC compounds present lower ClogP (lipophilicity) values than those found for the AD series and higher TPSA (topological polar surface area) values, suggesting lower lipophilicity may be related to the presence of the triazole connector. The AD series compounds have higher Drug Score values than the AC series derivatives, suggesting better general properties for a pharmacological action.

Design and synthesis of new 1,2,3-triazoles derived from eugenol and analogues with in vitro and in vivo activity against Trypanosoma cruzi

Chagas disease (CD) is a neglected tropical disease endemic in 21 countries and affects about 8 million people around the world. The pharmacotherapy for this disease is limited to two drugs (Benznidazole and Nifurtimox) and both are associated with important limitations, as low cure rate in the chronic phase of the disease, high toxicity and increasing resistance by Trypanosoma cruzi. Recently, we reported a bioactive 1,2,3-triazole (compound 35) active in vitro (IC₅₀ 42.8 μM) and in vivo (100 mg/kg) against T. cruzi Y strains and preliminary in silico studies suggested the cysteine protease cruzain as a possible target. Considering these initial findings, we describe here the design and synthesis of new 1,2,3-triazoles derivatives of our hit compound (35). The triazoles were initially evaluated against healthy cells derived from neonatal rat cardiomyoblasts (H9c2 cells) to determine their cytotoxicity and against epimastigotes forms of T. cruzi Y strain. The most active triazoles were compounds 26 (IC₅₀ 19.7 μM) and 27 (IC₅₀ 7.3 μM), while benznidazole was active at 21.6 μM. Derivative 27 showed an interesting selectivity index considering healthy H9c2 cells (>77). Promising activities against trypomastigotes forms of the parasite were also observed for triazoles 26 (IC₅₀ 20.74 μM) and 27 (IC₅₀ 8.41 μM), mainly 27 which showed activity once again higher than that observed for benznidazole (IC₅₀ 12.72 μM). While docking results suggested cruzain as a potential target for these compounds, no significant enzyme inhibition was observed in vitro, indicating that their trypanocidal activity is related to another mode of action. Considering the promising in vitro results of triazoles 26 and 27, the in vivo toxicity was initially verified based on the evaluation of behavioral and physiological parameters, mortality, effect in body weight gain, and through the measurement of AST/ALT enzymes, which are markers of liver toxicity. All these evaluations pointed to a good tolerability of the animals, especially considering triazole 27. A reduction in parasitemia was observed among animals treated with triazole 27, but not among those treated with derivative 26. Regarding the dosage, derivative 27 (100 mg/kg) was the most active sample against T. cruzi infection, showing a 99.4% reduction in parasitemia peak. Triazole 27 at a dosage of 100 mg/kg influenced the humoral immune response and reduced myocarditis in the animals, bringing antibody levels closer to those observed among healthy mice. Altogether, our results indicate compound 27 as a new lead for the development of drug candidates to treat Chagas disease.

Oxidative stress, cardiomyocytes senescence and contractile dysfunction in in vitro and in vivo experimental models of Chagas disease

AIMS

The relationship between redox imbalance and cardiovascular senescence in infectious myocarditis is unknown. Thus, the aim of this study was to investigate whether cardiomyocytes parasitism, oxidative stress and contractile dysfunction can be correlated to senescence-associated β-galactosidase (SA-β-Gal) activity in Trypanosoma cruzi-infection in vitro and in vivo.

METHODS

Uninfected, T. cruzi-infected untreated and benznidazole (BZN)-treated H9c2 cardiomyocytes and rats were investigated. Parasitological, prooxidant, antioxidant, microstructural, and senescence-associated markers were quantified in vitro and in vivo.

RESULTS

T. cruzi infection triggered intense cardiomyocytes parasitism in vitro and in vivo, which was accompanied by reactive oxygen species (ROS) upregulation, lipids, proteins and DNA oxidation in cardiomyocytes and cardiac tissue. Oxidative stress was parallel to microstructural cell damage (e.g., increased cardiac toponin I levels) and contractile dysfunction in cardiomyocytes in vitro and in vivo, whose severity accompanied a premature cellular senescence-like phenotype revealed by increased senescence-associated β-galactosidase (SA-β-Gal) activity and DNA oxidation (8-OHdG). Cellular parasitism (e.g., infection rate and parasite load), myocarditis and T. cruzi-induced prooxidant responses were attenuated by early BZN administration to interrupt the progression of T. cruzi infection, protecting against SA-β-gal-based premature cellular senescence, microstructural damage and contractile deterioration in cardiomyocytes from T. cruzi-infected animals.

CONCLUSION

Our findings indicated that cell parasitism, redox imbalance and contractile dysfunction were correlated to SA-β-Gal-based cardiomyocytes premature senescence in acute T. cruzi infection. Therefore, in addition to controlling parasitism, inflammation and oxidative stress; inhibiting cardiomyocytes premature senescence should be further investigated as an additional target of specific Chagas disease therapeutics.

New miconazole-based azoles derived from eugenol show activity against Candida spp. and Cryptococcus gattii by inhibiting the fungal ergosterol biosynthesis

This work describes the design, synthesis and antifungal activity of new imidazoles and 1,2,4-triazoles derived from eugenol and dihydroeugenol. These new compounds were fully characterized by spectroscopy/spectrometric analyses and the imidazoles 9, 10, 13 e 14 showed relevant antifungal activity against Candida sp. and Cryptococcus gattii in the range of 4.6-75.3 μM. Although no compound has shown a broad spectrum of antifungal activity against all evaluated strains, some azoles were more active than either reference drugs employed against specific strains. Eugenol-imidazole 13 was the most promising azole (MIC: 4.6 μM) against Candida albicans being 32 times more potent than miconazole (MIC: 150.2 μM) with no relevant cytotoxicity (selectivity index >28). Notably, dihydroeugenol-imidazole 14 was twice as potent (MIC: 36.4 μM) as miconazole (MIC: 74.9 μM) and more than 5 times more active than fluconazole (MIC: 209.0 μM) against alarming multi-resistant Candida auris. Furthermore, in vitro assays showed that most active compounds 10 and 13 altered the fungal ergosterol biosynthesis, reducing its content as fluconazole does, suggesting the enzyme lanosterol 14α-demethylase (CYP51) as a possible target for these new compounds. Docking studies with CYP51 revealed an interaction between the imidazole ring of the active substances with the heme group, as well as insertion of the chlorinated ring into a hydrophobic cavity at the binding site, consistent with the behavior observed with control drugs miconazole and fluconazole. The increase of azoles-resistant isolates of Candida species and the impact that C. auris has had on hospitals around the world reinforces the importance of discovery of azoles 9, 10, 13 e 14 as new bioactive compounds for further chemical optimization to afford new clinically antifungal agents.

Immunological Modulation and Control of Parasitaemia by Ayahuasca Compounds: Therapeutic Potential for Chagas's Disease

Ayahuasca is a psychoactive and psychedelic decoct composed mainly of Banisteriopsis caapi and Psychotria viridis plant species. The beverage is rich in alkaloids and it is ritualistically used by several indigenous communities of South America as a natural medicine. There are also reports in the literature indicating the prophylaxis potential of Ayahuasca alkaloids against internal parasites. In the present study, Ayahuasca exhibited moderate in vitro activity against Trypanosoma cruzi trypomastigotes (IC₅₀ 95.78 μg/mL) compared to the reference drug benznidazole (IC₅₀ 2.03 μg/mL). The β-carboline alkaloid harmine (HRE), isolated from B. caapi, was considered active against the trypomastigotes forms (IC₅₀ 6.37), and the tryptamine N, N-dimethyltryptamine (DMT), isolated from P. viridis was also moderately active with IC₅₀ of 21.02 μg/mL. Regarding the in vivo evaluations, no collateral effects were observed. The HRE alone demonstrated the highest trypanocidal activity in a dose-responsive manner (10 and 100 mg/kg). The Ayahuasca and the association between HRE and DMT worsened the parasitaemia, suggesting a modulation of the immunological response during the T. cruzi infection, especially by increasing total Immunoglobulin (IgG) and IgG1 antibody levels. The in silico molecular docking revealed HRE binding with low energy at two sites of the Trypanothione reductase enzyme (TR), which are absent in humans, and thus considered a promissory target for drug discovery. In conclusion, Ayahuasca compounds seem to not be toxic at the concentrations of the in vivo evaluations and can promote trypanocidal effect in multi targets, including control of parasitaemia, immunological modulation and TR enzymatic inhibition, which might benefit the treatments of patients with Chagas' disease. Moreover, the present study also provides scientific information to support the prophylactic potential of Ayahuasca against internal parasites.

In vivo anti-inflammatory activity of Fabaceae species extracts screened by a new ex vivo assay using human whole blood

INTRODUCTION

Plants have been considered a promising source for discovering new compounds with pharmacological activities. The Fabaceae family comprises a large variety of species that produce substances with diverse therapeutic potential, including anti-inflammatory activity. The limitations of current anti-inflammatories generate the need to research new anti-inflammatory structures with higher efficacy as well as develop methods for screening multiple samples, reliably and ethically, to assess such therapeutic properties.

OBJECTIVE

Validate and apply a quantification method for prostaglandin E₂ (PGE₂ ) production from an ex vivo assay in human blood in order to screen anti-inflammatory activity present in many Fabaceae species extracts.

METHODS

Human blood was incubated with extracts from 47 Fabaceae species. After lipopolysaccharide (LPS)-induced inflammation, PGE₂ was quantified in the plasma by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The extracts that presented PGE₂ production inhibition were further assessed through in vivo assay and then chemically characterised through an analysis of ultra-performance liquid chromatography electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-QTOF-MS² ) data.

RESULTS

The new ex vivo anti-inflammatory assay showed that five out of the 47 Fabaceae species inhibited PGE₂ production. Results from an in vivo assay and the metabolic profile of the active extracts supported the anti-inflammatory potential of four species.

CONCLUSION

The quantification method for PGE₂ demonstrated fast, sensitive, precise, and accurate results. The new ex vivo anti-inflammatory assay comprised a great, reliable, and ethical approach for the screening of a large number of samples before an in vivo bioassay. Additionally, the four active extracts in both ex vivo and in vivo assays may be useful for the development of more efficient anti-inflammatory drugs.

Synthesis of New Hybrid Derivatives from Metronidazole and Eugenol Analogues as Trypanocidal Agents

BACKGROUND

The search for new drug compounds is always challenging and there are several different strategies that involve the most varied and creative approaches in medicinal chemistry. One of them is the technique of molecular hybridisation: forming a hybrid compound from two or more pharmacophoric subunits. These hybrids may maintain the characteristics of the original compound and preferably show improvements to its pharmacological action, with reduced side effects and lower toxicity when compared to the original components. This study specifically focuses on synthesising hybrid molecules which demonstrate trypanocidal activity against the epimastigote and trypomastigote forms of Trypanosoma cruzi.

METHODS

In this context, this study centres on the synthesis of a novel structural scaffold via molecular hybridisation; by using a triazole species to link a metronidazole unit to a eugenol analogue unit, the objective being to combine their therapeutic properties into a new molecular structure. The resulting hybrid molecules were evaluated against T. cruzi which is responsible for high incidences of trypanosomiasis in tropical countries such as Brazil.

RESULTS

The results of this study showed an improvement in the anti-parasitic activity of the hybrid compounds with the best result coming from hybrid compounds [8] and [9], which present an activity similar to the control drug benznidazole. The new compounds, utilising a triazole species as a coupling connector, demonstrated promising results and has highlighted the path for planning similar structural patterns to investigate new compounds.

CONCLUSIONS

In summary, we can conclude that the synthesised hybrid compounds demonstrate that using a triazole to link metronidazole with natural phenols, produces hybrid molecules that are promising as a new class of compounds of therapeutic interest for further investigation.

Computer-Guided Trypanocidal Activity of Natural Lactones Produced by Endophytic Fungus of Euphorbia umbellata

Hundreds of millions of people worldwide are affected by Chagas' disease caused by Trypanosoma cruzi. Since the current treatment lack efficacy, specificity, and suffers from several side-effects, novel therapeutics are mandatory. Natural products from endophytic fungi have been useful sources of lead compounds. In this study, three lactones isolated from an endophytic strain culture were in silico evaluated for rational guidance of their bioassay screening. All lactones displayed in vitro activity against T. cruzi epimastigote and trypomastigote forms. Notably, the IC₅₀ values of (+)-phomolactone were lower than benznidazole (0.86 vs. 30.78 μM against epimastigotes and 0.41 vs. 4.88 μM against trypomastigotes). Target-based studies suggested that lactones displayed their trypanocidal activities due to T. cruzi glyceraldehyde-3-phosphate dehydrogenase (TcGAPDH) inhibition, and the binding free energy for all three TcGAPDH-lactone complexes suggested that (+)-phomolactone has a lower score value (-3.38), corroborating with IC₅₀ assays. These results highlight the potential of these lactones for further anti-T. cruzi drug development.

Synthesis, activity, and molecular modeling studies of 1,2,3-triazole derivatives from natural phenylpropanoids as new trypanocidal agents

The search for compounds with new structural scaffolds is an important tool to the discovery of new drugs against Chagas disease. We report herein the synthesis of 1,2,3-triazoles obtained from eugenol and di-hydroeugenol and their in vitro and in vivo trypanocidal activity. These derivatives were obtained by a three-step objective route and were suitably characterized by ¹ H and ¹³ C nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Two compounds (9 and 10) showed activity against epimastigote forms of Trypanosoma cruzi (Y strain) in the range 42.8-88.4 μM and were weakly toxic to cardiomyoblast cells (H9c2 cells). The triazole 10 was the most active derivative and could reduce more than 50% of parasitemia after a 100-mg/kg oral treatment of mice infected with T. cruzi. Molecular docking studies suggested this compound could act as a trypanocidal agent by inhibiting cruzain, an essential enzyme for T. cruzi metabolism, usually inhibited by triazole compounds.

Parasitaemia and parasitic load are limited targets of the aetiological treatment to control the progression of cardiac fibrosis and chronic cardiomyopathy in Trypanosoma cruzi-infected dogs

It is still unclear whether the progression of acute to chronic Chagas cardiomyopathy is predominantly associated with the limited efficacy of aetiological chemotherapy, or with the pharmacological resistance profiles and pathogenicity of specific Trypanosoma cruzi strains. Thus, we tested the hypothesis that parasitic load could be a limited target of aetiological chemotherapy to prevent chronic cardiomyopathy in dogs infected by different T. cruzi strains. Animals were infected with benznidazole-susceptible (Berenice-78) and -resistant (VL-10 and AAS) strains of T. cruzi. A quantitative real-time PCR strategy was developed to comparatively quantify the parasite load of the three different strains using a single standard curve. For dogs infected with the VL-10 strain, benznidazole treatment reduced cardiac parasitism during the acute phase of infection. However, similar parasite load and collagen deposition were detected in the myocardium of treated and untreated animals in the chronic phase of the infection. In animals infected with the AAS strain, benznidazole reduced parasite load, myocarditis and type III collagen deposition in the acute phase. However, increased type III collagen deposition was verified in the chronic phase. Dogs infected with the Berenice-78 strain showed a parasitological cure and no evidence of myocardial fibrosis. Parasitic load and cardiac fibrosis presented no correlation in acute or chronic phases of T. cruzi infection. Our findings in a canine model of Chagas disease suggest that parasite burden is a limited predictor for disease progression after treatment and show that benznidazole, although not inducing parasitological cure, is able to prevent total fibrosis in the early stages of infection, as well as complete prevention of cardiac damage when it eliminates parasites at the onset of infection.

Seroepidemiological aspects of human infection by Strongyloides stercoralis in Alfenas, southern Minas Gerais, Brazil

INTRODUCTION

In most Strongyloides stercoralis infected individuals, nematoidosis occurs asymptomatically, but in immunocompromised patients, it can cause hyperinfection. Serological techniques seem to be a good alternative for detecting this parasite.

METHODS

The frequency of seropositivity for strongyloidiasis in Alfenas, MG, was estimated using the enzyme linked immunosorbent assay on blood samples, between May and August of 2015.

RESULTS

Out of 258 samples tested, 53.9% were positive, and the frequency of seropositive individuals was higher in the peripheral districts of the municipality.

CONCLUSIONS

The results indicate high seropositivity rates for strongyloidiasis among the residents of Alfenas city.

Relevance of Trypanothione Reductase Inhibitors on Trypanosoma cruzi Infection: A Systematic Review, Meta-Analysis, and In Silico Integrated Approach

Due to the rudimentary antioxidant defenses in Trypanosoma cruzi, disruptors of redox balance are promising candidates for new antitrypanosomal drugs. We developed an integrated model based on systematic review, meta-analyses, and molecular modeling to evaluate the effect of trypanothione reductase (TR) inhibitors in T. cruzi infections. Our findings indicated that the TR inhibitors analyzed were effective in reducing parasitemia and mortality due to Trypanosoma cruzi infection in animal models. The most investigated drugs (clomipramine and thioridazine) showed no beneficial effects on the occurrence of infection-related electrocardiographic abnormalities or the affinity and density of cardiac β-adrenergic receptors. The affinity between the tested ligands and the active site of TR was confirmed by molecular docking. However, the molecular affinity score was unable to explain TR inhibition and T. cruzi death in vitro or the antiparasitic potential of these drugs when tested in preclinical models of T. cruzi infection. The divergence of in silico, in vitro, and in vivo findings indicated that the anti-T. cruzi effects of the analyzed drugs were not restricted to TR inhibition. As in vivo studies on TR inhibitors are still scarce and exhibit methodological limitations, mechanistic and highly controlled studies are required to improve the quality of evidence.

In vitro and in vivo trypanocidal activities of 8-methoxy-3-(4-nitrobenzoyl)-6-propyl-2H-cromen-2-one, a new synthetic coumarin of low cytotoxicity against mammalian cells

Natural and synthetic coumarins have been described as prototypes of new drug candidates against Chagas' disease. During a typical screening with new compounds, we observed the potential of a new synthetic nitrobenzoylcoumarin (1) as trypanocidal against Trypanosoma cruzi epimastigotas. Then, we decided to prepare and evaluate a set of analogues from 1 to check the major structural requirements for trypanocidal activity. The structural variations were conducted in six different sites on the original compound and the best derivative (3) presented activity (IC₅₀ 28 ± 3 μM) similar to that of benznidazole (IC₅₀ 25 ± 10 μM). The enhancement of trypanocidal activity was conditioned to a change in the side chain at C6 (allyl to n-propyl group) and the preservation of coumarin nucleus and the nitrobenzoyl group at C3. Exposure of 3 to H9C2 cells showed low toxicity (CC₅₀  > 200 μM) and its activity on T. cruzi amastigotes (IC₅₀ 13 ± 0.3 μM) encouraged us to perform an evaluation of its potential when given orally to mice infected with trypomastigote forms. Derivative 3 was able to reduce parasitemia when compared to the group of untreated animals. Taken together, these results show the potential therapeutic application of the synthetic coumarins.

Could age and aging change the host response to systemic parasitic infections? A systematic review of preclinical evidence

The impact of age and aging in the evolution of systemic parasitic infections remains poorly understood. We conducted a systematic review from preclinical models of Chagas disease, leishmaniasis, malaria, sleeping sickness and toxoplasmosis. From a structured and comprehensive search in electronic databases, 29 studies were recovered and included in the review. Beyond the characteristics of the experimental models, parasitological and immunological outcomes, we also discussed the quality of current evidence. Our findings indicated that throughout aging, parasitemia and mortality were consistently reduced in Chagas disease and malaria, but were similar or increased in leishmaniasis and highly variable in toxoplasmosis. While a marked humoral response in older animals was related to the anti-T. cruzi protective phenotype, cellular responses mediated by a polarized Th1 phenotype were associated with a more effective defense against Plasmodium infection. Conversely, in leishmaniasis, severe infections and high mortality rates were potentially related to attenuation of humoral response and an imbalance between Th1 and Th2 phenotypes. Due to the heterogeneous parasitological outcomes and limited immunological data, the role of aging on toxoplasmosis evolution remains unclear. From a detailed description of the methodological bias, more controlled researches could avoid the systematic reproduction of inconsistent and poorly reproducible experimental designs.

Lipopolysaccharide-induced acute lung injury in mice chronically infected by Schistosoma mansoni

We used a murine model of Schistosoma mansoni (SM) infection and lipopolysaccharide (LPS)-induced endotoxicity to investigate if these conditions can interact to modify the pathological manifestations typically observed in each condition. Swiss mice were randomized into four groups: SAL, uninfected; SM, infected; LPS, uninfected + LPS; and SM + LPS, infected + LPS. S. mansoni infection developed over 120 days, after which blood samples and lungs were collected, peritoneal leukocytes were isolated and cultivated for 6 and 24 h after LPS inoculation (1 mL/kg). Infected animals presented marked granulomatous inflammation. LPS exposure transiently modified the profile of leucocyte migration into the lung tissue and increased NO production by isolated leukocytes, without inducing any acute effect on the structure of schistosomiasis granulomas. Beyond modifying lung morphology, S. mansoni and LPS interacted to modulate the circulating levels of cytokines. S. mansoni infection restricted INF-γ upregulation 6 and 24 h after LPS administration. Conversely, 24 h after inoculation, LPS increased IL-2 and IL-5 levels. Our findings indicate that LPS impaired the lung microenvironment by acutely disrupting inflammatory homeostatic mechanisms that control lung schistosomiasis. As schistosomiasis develops as a chronic condition, long-term exposure to endotoxins could aggravate the granulomatous process, an issue that requires further investigation.

S. mansoni-T. cruzi co-infection modulates arginase-1/iNOS expression, liver and heart disease in mice

Although Schistosoma species and Trypanosoma cruzi share common endemic areas, co-infections by these parasites remains overlooked. By using a murine model of S. mansoni and T. cruzi co-infection, we investigated if and to what extent these infections might interact to change the pathological outcomes typically observed when the host is infected by a single parasite species. Swiss mice were randomized into four groups: uninfected (NI) and those infected by S. mansoni (SM), T. cruzi (TC) or co-infected (SM + TC). After 120 days of S. mansoni infection, T. cruzi was concurrently inoculated and the infection occurred for 30 days. Taken together, we identified that the overlap of Th2 (schistosomiasis) and Th1 (Chagas disease) immunological patterns changes the host resistance against both pathogens. Beyond impairing the control of granulomatous inflammation, T. cruzi parasitemia and parasitism in co-infected animals, the Th2 inflammatory response against S. mansoni elicits the activation of the arginase-1 pathway to the detriment of inducible oxide nitric synthase (iNOS) expression and nitric oxide (NO) production, contributing to the liver damage, with minor effects on heart pathology.

Myocarditis in different experimental models infected by Trypanosoma cruzi is correlated with the production of IgG1 isotype

This study was designed to verify the relationship between IgG antibodies isotypes and myocarditis in Trypanosoma cruzi infection using mice and dogs infected with different T. cruzi strains. The animals were infected with benznidazole-susceptible Berenice-78 and benznidazole-resistant AAS and VL-10 strains. The IgG subtypes were measured in serum samples from dogs (IgG, IgG1, and IgG2) and mice (IgG, IgG1, IgG2a, and IgG2b). The infection of dogs with VL-10 strain induced the highest levels of heart inflammation while intermediate and lower levels were detected with Berenice-78 and AAS strains, respectively. Similar results were found in mice infected with VL-10, but not in those infected with AAS or Berenice-78 strains. The AAS strain induced higher levels of heart inflammation in mice, while Berenice-78 strain was not able to induce it. Correlation analysis between myocarditis and antibody reactivity index revealed very interesting results, mainly for IgG and IgG1, the latter being the most exciting. High IgG1 showed a significant correlation with myocarditis in both experimental models, being more significant in dogs (r=0.94, p<0.0001) than in mice (r=0.58, p=0.047). Overall, our data suggest that IgG1 could be a good marker to demonstrate myocarditis intensity in Chagas disease.

Vasoactive intestinal peptide reduces the inflammatory profile in mice infected with Trypanosoma cruzi

Vasoactive intestinal peptide (VIP) has gained great prominence because of its therapeutic potential, which is ascribed to its ability to regulate innate immunity, inhibit antigen-specific Th1 cell responses, and generate T regulatory cells. Additionally, VIP may act as a natural antimicrobial peptide, killing bacteria, fungi, and infective forms of Trypanosoma brucei. Despite the possible relevance of VIP during the course of Chagas disease, studies regarding this in human and experimental Trypanosoma cruzi infections remain poorly characterized. In this work, we evaluated the effects of VIP on systemic and cardiac immune responses during experimental acute infection. C57BL/6 mice were infected with 5000 trypomastigotes of the VL-10 strain of T. cruzi and treated with intraperitoneal VIP injection every other day for one month. After 30 days, we observed no reduction in parasitemia levels. However, we observed a reduction in serum levels of IFN-gamma and IL-2 and an increase in that of IL-4. These data suggest that VIP treatment modified immune responses to favor the Th2 response, which had no impact on parasitemia levels although the serum level of IFN-gamma was reduced. However, this change in immune balance reduced heart damage, as noted by the smaller cardiac volume and the moderate inflammatory infiltrate observed in VIP-treated mice. Our results indicate that VIP treatment reduced the inflammatory response at the cardiac site of mice that were experimentally infected with T. cruzi. These data suggest a protective role for VIP in the heart of infected mice.

Benznidazole/Itraconazole Combination Treatment Enhances Anti-Trypanosoma cruzi Activity in Experimental Chagas Disease

The nitroheterocyclic drugs nifurtimox and benznidazole are first-line drugs available to treat Chagas disease; however, they have limitations, including long treatment courses and toxicity. Strategies to overcome these limitations include the identification of new drugs with specific target profiles, re-dosing regimens for the current drugs, drug repositioning and combination therapy. In this work, we evaluated combination therapy as an approach for optimization of the current therapeutic regimen for Chagas disease. The curative action of benznidazole/itraconazole combinations was explored in an established infection of the mice model with the T. cruzi Y strain. The activities of the benznidazole/itraconazole combinations were compared with the results from those receiving the same dosage of each individual drug. The administration of benznidazole/itraconazole in combination eliminated parasites from the blood more efficiently than each drug alone. Here, there was a significant reduction of the number of treatment days (number of doses) necessary to induce parasitemia suppression with the benznidazole/itraconazole combination, as compared to each compound administered alone. These results clearly indicate the enhanced effects of these drugs in combination, particularly at the dose of 75 mg/kg, as the effects observed with the drug combinations were four times more effective than those of each drug used alone. Moreover, benznidazole/itraconazole treatment was shown to prevent or decrease the typical lesions associated with chronic experimental Chagas disease, as illustrated by similar levels of inflammatory cells and fibrosis in the cardiac muscle tissue of healthy and treated mice. These results emphasize the importance of exploring the potential of combination treatments with currently available compounds to specifically treat Chagas disease.

Therapeutic responses to different anti-Trypanosoma cruzi drugs in experimental infection by benznidazole-resistant parasite stock

SUMMARY This study describes the role of parasite clearance time induced by benznidazole, fexinidazole and posaconazole treatments upon mice infection with a benznidazole-resistant Trypanosoma cruzi strain in the pathological outcomes. Trypanosoma cruzi-infected mice were treated with different drugs and parasite clearance time was detected by blood and tissue qPCR, to determine the dynamic relationship between the efficacy of the treatments and the intensity of heart lesion/serum inflammatory mediators. Our results indicate that anti-T. cruzi treatments were able to reduce parasite replication and consequently induce immunomodulatory effects, where the degree of the immunopathology prevention was related to the time of parasite clearance induced by different treatments. Nevertheless, in benznidazole and posaconazole treatments, parasite rebounding was detected with parasitism reaching levels similar to infected and non-treated mice; the time for parasitic rebound being earlier among benznidazole-treated mice. In parallel, an increase of cardiac lesions and plasma chemokine levels was also detected and was more accentuated in benznidazole-treated animals. Interestingly, in the presence of parasitological cure (fexinidazole treatment), basal levels of these inflammatory mediators were evidenced as well as an absence of cardiac inflammation or fibrosis. Overall, our data indicate that all treatments have positive effects on the clinical evolution of T. cruzi infection, with success in preventing cardiac alterations being drug-dependent.

Association between nutritional status, C-reactive protein, adiponectin and HOMA-AD in Brazilian children

INTRODUCTION

In children, the presence of obesity is a major risk factor for the occurrence of cardiovascular diseases on the adulthood.

OBJECTIVE

To evaluate the association of anthropometry, body composition, clinical variables and biochemical profile with C-reactive protein and adiponectin levels, and insulin resistance in children in the municipality of Nova Era, Brazil.

METHODS

Nested case-control study following a crosssectional study. We evaluated 178 children, 57 of them classified as obese and 121 as normal-weight from a population of 1024 schoolchildren 6 to 10 years old: Blood samples were collected after 12-hour fast to obtain serum and plasma. We collected anthropometric and body composition measures, systolic and diastolic blood pressure data. Sexual maturation was assessed according to the stage of sexual development. We performed Student's t-test, Mann-Whitney U test, Pearson's correlation, Spearman's test and multiple linear regression analysis. Independent variables with p < 0.05 were included in the multiple regression model. Residual analysis was performed to assess model validity.

RESULTS

Among obese children, C-reactive protein levels were associated with triacylglycerol levels and body fat percentage estimated by skinfold thickness (R2 adjusted = 27.6%, p < 0.001). Adiponectin was associated with HOMA-IR, HOMAAD and body fat percentage estimated by skinfold thickness (R2 adjusted = 75.5%, p < 0.001). HOMA-AD index was associated with HOMA-IR, adiponectin, systolic blood pressure and weight (R2 adjusted = 90.7%, p < 0.001).

CONCLUSION

Significant associations were found between body composition, anthropometry, clinical variables, biochemical profile and adiponectin and C-reactive protein levels and insulin resistance in obese and normal-weight children.

Myenteric plexus is differentially affected by infection with distinct Trypanosoma cruzi strains in Beagle dogs

Chagasic megaoesophagus and megacolon are characterised by motor abnormalities related to enteric nervous system lesions and their development seems to be related to geographic distribution of distinct Trypanosoma cruzi subpopulations. Beagle dogs were infected with Y or Berenice-78 (Be-78) T. cruzi strains and necropsied during the acute or chronic phase of experimental disease for post mortem histopathological evaluation of the oesophagus and colon. Both strains infected the oesophagus and colon and caused an inflammatory response during the acute phase. In the chronic phase, inflammatory process was observed exclusively in the Be-78 infected animals, possibly due to a parasitism persistent only in this group. Myenteric denervation occurred during the acute phase of infection for both strains, but persisted chronically only in Be-78 infected animals. Glial cell involvement occurred earlier in animals infected with the Y strain, while animals infected with the Be-78 strain showed reduced glial fibrillary acidic protein immunoreactive area of enteric glial cells in the chronic phase. These results suggest that although both strains cause lesions in the digestive tract, the Y strain is associated with early control of the lesion, while the Be-78 strain results in progressive gut lesions in this model.

Benznidazole and posaconazole in experimental Chagas disease: positive interaction in concomitant and sequential treatments

Background

Current chemotherapy for Chagas disease is unsatisfactory due to its limited efficacy, particularly in the chronic phase, with frequent side effects that can lead to treatment discontinuation. Combined therapy is envisioned as an ideal approach since it may improve treatment efficacy whilst decreasing toxicity and the likelihood of resistance development. We evaluated the efficacy of posaconazole in combination with benznidazole on Trypanosoma cruzi infection in vivo.

Methods and Findings

Benznidazole and posaconazole were administered individually or in combination in an experimental acute murine infection model. Using a rapid treatment protocol for 7 days, the combined treatments were more efficacious in reducing parasitemia levels than the drugs given alone, with the effects most evident in combinations of sub-optimal doses of the drugs. Subsequently, the curative action of these drug combinations was investigated, using the same infection model and 25, 50, 75 or 100 mg/kg/day (mpk) of benznidazole in combination with 5, 10 or 20 mpk of posaconazole, given alone or concomitantly for 20 days. The effects of the combination treatments on parasitological cures were higher than the sum of such effects when the drugs were administered separately at the same doses, indicating synergistic activity. Finally, sequential therapy experiments were carried out with benznidazole or posaconazole over a short interval (10 days), followed by the second drug administered for the same period of time. It was found that the sequence of benznidazole (100 mpk) followed by posaconazole (20 mpk) provided cure rates comparable to those obtained with the full (20 days) treatments with either drug alone, and no cure was observed for the short treatments with drugs given alone.

Conclusions

Our data demonstrate the importance of investigating the potential beneficial effects of combination treatments with marketed compounds, and showed that combinations of benznidazole with posaconazole have a positive interaction in murine models of Chagas disease.

In this study, we investigated the efficacy of posaconazole in combination with benznidazole against Trypanosoma cruzi acute infections in mice, to support the potential clinical evaluation of such combination therapy for Chagas disease. The curative action of benznidazole/posaconazole combinations was explored in an established acute infection model with the Y strain in which benznidazole and posaconazole treatments induced a 70% and 80% cure rate, respectively, when administered alone at optimal doses. When tested in combination, a 80% to 90% cure rate was detected in mice receiving 25, 50 or 75 mpk of benznidazole, plus 5 or 10 mpk of posaconazole, while treatment with the sub-optimal doses of the drugs given alone induced only 0–43% cures, indicating synergistic effects. Finally, sequential short (10 days) treatments with benznidazole (100 mpk) followed by posaconazole (20 mpk) led to an 80% cure rate, comparable with full-length treatments with either drug given alone, while no cures were observed for short treatments with single drugs. Our results demonstrate that it is possible to achieve the same or better therapeutic effect using lower dosages of posaconazole and benznidazole in combination, decreasing treatment costs and potential toxicity.

Recombinant Leishmania (Leishmania) infantum Ecto-Nucleoside Triphosphate Diphosphohydrolase NTPDase-2 as a new antigen in canine visceral leishmaniasis diagnosis

Canine visceral leishmaniasis is an important public health concern. In the epidemiological context of human visceral leishmaniasis, dogs are considered the main reservoir of Leishmania parasites; therefore, dogs must be epidemiologically monitored constantly in endemic areas. Furthermore, dog to human transmission has been correlated with emerging urbanization and increasing rates of leishmaniasis infection worldwide. Leishmania (Leishmania) infantum (L. chagasi) is the etiologic agent of visceral leishmaniasis in the New World. In this work, a new L. (L.) infantum (L. chagasi) recombinant antigen, named ATP diphosphohydrolase (rLic-NTPDase-2), intended for use in the immunodiagnosis of CVL was produced and validated. The extracellular domain of ATP diphosphohydrolase was cloned and expressed in the pET21b-Escherichia coli expression system. Indirect ELISA assays were used to detect the purified rLic-NTPDase-2 antigen using a standard canine sera library. This library contained CVL-positive samples, leishmaniasis-negative samples and samples from Trypanosoma cruzi-infected dogs. The results show a high sensitivity of 100% (95% CI=92.60-100.0%) and a high specificity of 100% (95% CI=86.77-100.0%), with a high degree of confidence (k=1). These findings demonstrate the potential use of this recombinant protein in immune diagnosis of canine leishmaniasis and open the possibility of its application to other diagnostic approaches, such as immunochromatography fast lateral flow assays and human leishmaniasis diagnosis.

Myocardial scars correlate with eletrocardiographic changes in chronic Trypanosoma cruzi infection for dogs treated with Benznidazole

OBJECTIVES

The cardiac form of Chagas disease is evidenced by a progressive cardiac inflammation that leads to myocarditis, fibrosis and electrocardiographic (ECG) conduction abnormalities. Considering these characteristics, the aim of this study was to prospectively evaluate the early ECG changes in dogs that were experimentally inoculated with Benznidazole (Bz)-susceptibly (Berenice-78) and Bz-resistant (VL-10, and AAS) Trypanosoma cruzi strains and, later, evaluate the efficacy of Bz treatment for preventing these ECG alterations.

METHODS

Electrocardiographic changes of treated and untreated animals were prospectively evaluated for up to 270 days after infection, at which point collagen (right atrium) quantification was performed.

RESULTS

All infected dogs had a high intensity of heart fibrosis (4616.00 ± 1715.82 collagen/74931 μm(2) in dogs infected with Berenice-78 strain, 5839.2 ± 1423.49 collagen/74931 μm(2) in infected by AAS and 6294.40 ± 896.04 collagen/74931 μm(2) in animals infected with VL-10 strain), while 78.57% of all infected dogs showed ECG alterations. Bz Therapy reduced or prevented fibrosis in Bz-susceptible Berenice-78 (2813.00 ± 607.13 collagen/74931 μm(2) ) and Bz-resistant AAS strains (4024 ± 1272.44 collagen/74931 μm(2) ), coincident with only 10% de ECG alterations at 270 days. However, in those animals infected with a Bz-resistant VL-10 strain, specific treatment did not alter collagen deposition (6749.5 ± 1596.35 collagen/74931 μm(2) ) and there was first atrioventricular block and chamber overload at 120 and 270 days after infection, with 75% abnormal ECG exams.

CONCLUSIONS

These findings indicate that an effective antiparasitic treatment in the early stage of Chagas disease can lead to a significant reduction in the frequency and severity of the parasite-induced cardiac disease, even if parasites are not completely eliminated.

Real-time PCR strategy for parasite quantification in blood and tissue samples of experimental Trypanosoma cruzi infection

The lack of an accurate diagnosis has been a serious obstacle to the advancement of the anti-Trypanosoma cruzi chemotherapy and long-term infection can result in different health risks to human. PCRs are alternative methods, more sensitive than conventional parasitological techniques, which due to their low sensitivities are considered unsuitable for these purposes. The aim of this study was to investigate a sensitive diagnostic strategy to quantify blood and cardiac tissues parasites based on real-time PCR tools during acute and chronic phases of murine Chagas disease, as well as to monitor the evolution of infection in those mice under specific treatment. In parallel, fresh blood examination, immunological analysis and quantification of cardiac inflammation were also performed to confront and improve real-time PCR data. Similar profiles of parasitemia curves were observed in both quantification techniques during the acute phase of the infection. In contrast, parasites could be quantified only by real-time PCR at 60 and 120 days of infection. In cardiac tissue, real-time PCR detected T. cruzi DNA in 100% of infected mice, and using this tool a significant Pearson correlation between parasite load in peripheral blood and in cardiac tissue during acute and chronic phases was observed. Levels of serum CCL2, CCL5 and nitric oxide were coincident with parasite load but focal and diffuse mononuclear infiltrates was observed, even with significant (p<0.05) reduction of parasitism after 60 days of infection. Later, this methodology was used to monitor the evolution of infection in animals treated with itraconazole (Itz). Itz-treatment induced a reduction of parasite load in both blood and cardiac muscle at the treatment period, but after the end of chemotherapy an increase of parasitism was detected. Interestingly, inflammatory mediators levels and heart inflammation intensity had similar evolution to the parasite load, in the group of animals treated. Taken together, our data show that real-time PCR strategy used was suitable for studies of murine T. cruzi infection and may prove useful in investigations involving experimental chemotherapy of the disease and the benefits of treatment in relation to parasitism and inflammatory response.

Hematological alterations during experimental canine infection by Trypanosoma cruzi

To confirm that Beagle dogs are a good experimental model for Chagas disease, we evaluated hematological alterations during the acute and chronic phases in Beagle dogs infected with the Y, Berenice-78 (Be-78) and ABC strains of Trypanosomacruzi, correlating clinical signs with the parasitemia curve. We demonstrate that the acute phase of infection was marked by lethargy and loss of appetite. Simultaneously, we observed anemia, leukocytosis and lymphocytosis. Also,we describe hematological alterations and clinical signs that were positively correlated with the parasitemia during the experimental infection with the three strains of T.cruzi, and demonstrate that experimental infection of Beagle is a trustworthy model for Chagas disease.

Genetic modulation in Be-78 and Y Trypanosoma cruzi strains after long-term infection in Beagle dogs revealed by molecular markers

The genetic profile of Trypanosoma cruzi was evaluated in parasite populations isolated from Beagle dogs experimentally infected with Be-78 and Y strains that present distinct biological and genetic characteristics. Molecular characterization of the isolates obtained 30days and 2years after infection was carried out. For typing MLEE, sequence polymorphisms of the mitochondrial cytochrome oxidase subunit II gene (COII) and RAPD profiles were used. The profiles of MLEE were the same for the parental Be-78 strains as their respective isolates. However, changes of MLEE profile were observed in two T. cruzi isolates from dogs inoculated with Y strain. Changes in the mitochondrial DNA (COII) and RAPD profiles of the Y strain were also observed. The dendogram constructed by UPGMA with RAPD results indicated two major branches. Global data show that the genetic modulation in polyclonal strains during the long-term infection occurred and was strain-dependent. This study still suggests that each host (here each dog) harbors a determinate T. cruzi population that may change or be modulated throughout long-term infection. This might to hinder the observation of correlation between the genetics of T. cruzi and their biological properties and behavior in different host species due to the complexity of the parasite-host interaction in which probably the genetic background of both should be considered.

Canine visceral leishmaniasis in the Krenak indigenous community, Resplendor, Minas Gerais State, Brazil, 2007

The authors conducted a cross-sectional study of the local canine population in the Krenak indigenous community to detect parasites of the genus Leishmania and identify the circulating species and the proportion of asymptomatic dogs, while investigating associations between canine infection and the dogs' sex, age, and hair length. A seroepidemiological survey was performed, including 63 dogs. All the animals underwent clinical examination to verify the presence of characteristic signs, and serum samples were taken for serological tests (ELISA, IIF). Infected dogs culled by the health service were necropsied and the material was analyzed using molecular diagnostic techniques. The cross-sectional study detected a 46% prevalence rate, and the circulating species was Leishmania (L.) chagasi. The statistical analysis showed no association between infection and the independent variables. The study generated data on the epidemiological situation with canine infection in the area, which was previously unknown.

Low doses of simvastatin therapy ameliorate cardiac inflammatory remodeling in Trypanosoma cruzi-infected dogs

Chagas cardiomyopathy remodeling is based on the presence of Trypanosoma cruzi in heart tissue and on the complex inflammatory response leading to a myocardium fibrosis and alterations in conductive and functional heart parameters. This study aims to evaluate Simvastatin on the inflammatory response and heart functionality using dogs infected with Y strain of T. cruzi. Animals were treated daily with Simvastatin (20 mg) for 6 months and submitted to clinical and immunopathological evaluations. Simvastatin reduced heart expression and serum levels of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) but not interleukin-10 (IL-10), possibly favoring blood parasitism but reducing inflammation and fibrosis in the left ventricle and right atrium. Simvastatin also ameliorated ejection fraction, diastolic diameter, and mass index of the left ventricle 6 months after infection. This study suggests that more investigation should be performed on the use of statins as a prophylactic therapy against cardiac remodeling because of their effects on modifying immune response and benefiting functional parameters in dogs with T. cruzi-induced ventricular dysfunctions.