Current and developing therapeutic agents in the treatment of Chagas disease

Screening of synthetic 1,2,3-triazolic compounds inspired by SRPIN340 as anti-Trypanosoma cruzi agents

BACKGROUND

The current treatments for Chagas disease (CD) include benznidazole and nifurtimox, which have limited efficacy and cause numerous side effects. Triazoles are candidates for new CD treatments due to their ability to eliminate T. cruzi parasites by inhibiting ergosterol synthesis, thereby damaging the cell membranes of the parasite.

METHODS

Eleven synthetic analogs of the kinase inhibitor SRPIN340 containing a triazole core (compounds 6A-6K) were screened in vitro against the Tulahuen strain transfected with β-galactosidase, and their IC50, CC50, and selectivity indexes (SI) were calculated. Compounds with an SI > 50 were further evaluated in mice infected with the T. cruzi Y strain by rapid testing.

RESULTS

Eight compounds were active in vitro with IC50 values ranging from 0.5-10.5 µg/mL. The most active compounds, 6E and 6H, had SI values of 125.2 and 69.6, respectively. These compounds also showed in vivo activity, leading to a reduction in parasitemia at doses of 10, 50, and 250 mg/kg/day. At doses of 50 and 250 mg/kg/day, parasitemia was significantly reduced compared to infected untreated animals, with no significant differences between the effects of 6E and 6H.

CONCLUSIONS

This study identified two new promising compounds for CD chemotherapy and confirmed their activity against T. cruzi.

Listen to what the animals say: a systematic review and meta-analysis of sterol 14-demethylase inhibitor efficacy for in vivo models of Trypanosoma cruzi infection

Sterol 14-demethylase (CYP51) inhibitors, encompassing new chemical entities and repurposed drugs, have emerged as promising candidates for Chagas disease treatment, based on preclinical studies reporting anti-Trypanosoma cruzi activity. Triazoles like ravuconazole (RAV) and posaconazole (POS) progressed to clinical trials. Unexpectedly, their efficacy was transient in chronic Chagas disease patients, and their activity was not superior to benznidazole (BZ) treatment. This paper aims to summarize evidence on the global activity of CYP51 inhibitors against T. cruzi by applying systematic review strategies, risk of bias assessment, and meta-analysis from in vivo studies. PubMed and Embase databases were searched for original articles, obtaining fifty-six relevant papers meeting inclusion criteria. Characteristics of animal models, parasite strain, treatment schemes, and cure rates were extracted. Primary outcomes such as maximum parasitaemia values, survival, and parasitological cure were recorded for meta-analysis, when possible. The risk of bias was uncertain in most studies. Animals treated with itraconazole, RAV, or POS survived significantly longer than the infected non-treated groups (RR = 4.85 [3.62, 6.49], P < 0.00001), and they showed no differences with animals treated with positive control drugs (RR = 1.01 [0.98, 1.04], P = 0.54). Furthermore, the overall analysis showed that RAV or POS was not likely to achieve parasitological cure when compared with BZ or NFX treatment (OD = 0.49 [0.31, 0.77], P = 0.002). This systematic review contributes to understanding why the azoles had failed in clinical trials and, more importantly, how to improve the animal models of T. cruzi infection by filling the gaps between basic, translational, and clinical research.

Trypanosoma cruzi killing and immune response boosting by novel phenoxyhydrazine-thiazole against Chagas disease

Trypanosoma cruzi (T. cruzi) causes Chagas, which is a neglected tropical disease (NTD). WHO estimates that 6 to 7 million people are infected worldwide. Current treatment is done with benznidazole (BZN), which is very toxic and effective only in the acute phase of the disease. In this work, we designed, synthesized, and characterized thirteen new phenoxyhydrazine-thiazole compounds and applied molecular docking and in vitro methods to investigate cell cytotoxicity, trypanocide activity, nitric oxide (NO) production, cell death, and immunomodulation. We observed a higher predicted affinity of the compounds for the squalene synthase and 14-alpha demethylase enzymes of T. cruzi. Moreover, the compounds displayed a higher predicted affinity for human TLR2 and TLR4, were mildly toxic in vitro for most mammalian cell types tested, and LIZ531 (IC50 2.8 μM) was highly toxic for epimastigotes, LIZ311 (IC50 8.6 μM) for trypomastigotes, and LIZ331 (IC50 1.9 μM) for amastigotes. We observed that LIZ311 (IC50 2.5 μM), LIZ431 (IC50 4.1 μM) and LIZ531 (IC50 5 μM) induced 200 μg/mL of NO and JM14 induced NO production in three different concentrations tested. The compound LIZ331 induced the production of TNF and IL-6. LIZ311 induced the secretion of TNF, IFNγ, IL-2, IL-4, IL-10, and IL-17, cell death by apoptosis, decreased acidic compartment formation, and induced changes in the mitochondrial membrane potential. Taken together, LIZ311 is a promising anti-T. cruzi compound is not toxic to mammalian cells and has increased antiparasitic activity and immunomodulatory properties.

Anti-trypanosomal Lignans Isolated from Salvadoran Peperomia pseudopereskiifolia

A search for anti-trypanosomal natural compounds from plants collected in El Salvador, a country particularly endemic for Chagas disease, resulted in the isolation of five lignan-type compounds (1-5) from Peperomia pseudopereskiifolia. The lignan derivatives 1, 2, and 4 are new. Their absolute configuration was determined by chemical derivatization. Compounds 1, 5, 6, and 8 exhibited anti-trypanosomal activity against the amastigote form of T. cruzi comparable to that of the existing drug benznidazole.

Elongation on aliphatic chain improves selectivity of 2-hydroxy-3,4,6-trimethoxyphenyl chalcone on Trypanosoma cruzi

Aim: Our objective was to investigate the trypanocidal effect of the chalcone (2E,4E)-1-(2-hydroxy-3,4,6-trimethoxyphenyl)-5-phenylpenta-2,4-dien-1-one (CPNC). Material & methods: Cytotoxicity toward LLC-MK2 host cells was assessed by MTT assay, and the effect on Trypanosoma cruzi life forms (epimastigotes, trypomastigotes and amastigotes) was evaluated by counting. Flow cytometry analysis was performed to evaluate the possible mechanisms of action. Finally, molecular docking simulations were performed to evaluate interactions between CPNC and T. cruzi enzymes. Results: CPNC showed activity against epimastigote, trypomastigote and amastigote life forms, induced membrane damage, increased cytoplasmic reactive oxygen species and mitochondrial dysfunction on T. cruzi. Regarding molecular docking, CPNC interacted with both trypanothione reductase and TcCr enzymes. Conclusion: CPNC presented a trypanocidal effect, and its effect is related to oxidative stress, mitochondrial impairment and necrosis.

Miltefosine and Benznidazole Combination Improve Anti-Trypanosoma cruzi In Vitro and In Vivo Efficacy

Drug repurposing and combination therapy have been proposed as cost-effective strategies to improve Chagas disease treatment. Miltefosine (MLT), a synthetic alkylphospholipid initially developed for breast cancer and repositioned for leishmaniasis, is a promising candidate against Trypanosoma cruzi infection. This study evaluates the efficacy of MLT as a monodrug and combined with benznidazole (BZ) in both in vitro and in vivo models of infection with T. cruzi (VD strain, DTU TcVI). MLT exhibited in vitro activity on amastigotes and trypomastigotes with values of IC_{50 =} 0.51 µM (0.48 µM; 0,55 µM) and LC_{50 =} 31.17 µM (29.56 µM; 32.87 µM), respectively. Drug interaction was studied with the fixed-ration method. The sum of the fractional inhibitory concentrations (ΣFICs) resulted in ∑FIC= 0.45 for trypomastigotes and ∑FIC= 0.71 for amastigotes, suggesting in vitro synergistic and additive effects, respectively. No cytotoxic effects on host cells were observed. MLT efficacy was also evaluated in a murine model of acute infection alone or combined with BZ. Treatment was well tolerated with few adverse effects, and all treated animals displayed significantly lower mean peak parasitemia and mortality than infected non-treated controls (p<0.05). The in vivo studies showed that MLT led to a dose-dependent parasitostatic effect as monotherapy which could be improved by combining with BZ, preventing parasitemia rebound after a stringent immunosuppression protocol. These results support MLT activity in clinically relevant stages from T. cruzi, and it is the first report of positive interaction with BZ, providing further support for evaluating combined schemes using MLT and exploring synthetic alkylphospholipids as drug candidates.

Anti-trypanosomal screening of Salvadoran flora

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, and in Central America, it is considered one of the four most infectious diseases. This study aimed to screen the anti-trypanosomal activity of plant species from Salvadoran flora. Plants were selected through literature search for plants ethnobotanically used for antiparasitic and Chagas disease symptomatology, and reported in Museo de Historia Natural de El Salvador (MUHNES) database. T. cruzi was incubated for 72 h with 2 different concentrations of methanolic extracts of 38 species, among which four species, Piper jacquemontianum, Piper lacunosum, Trichilia havanensis, and Peperomia pseudopereskiifolia, showed the activity (≤ 52.0% viability) at 100 µg/mL. Separation of the methanolic extract of aerial parts from Piper jacquemontianum afforded a new flavanone (4) and four known compounds, 2,2-dimethyl-6-carboxymethoxychroman-4-one (1), 2,2-dimethyl-6-carboxychroman-4-one (2), cardamomin (3), and pinocembrin (5), among which cardamomin exhibited the highest anti-trypanosomal activity (IC₅₀ = 66 µM). Detailed analyses of the spectral data revealed that the new compound 4, named as jaqueflavanone A, was a derivative of pinocembrin having a prenylated benzoate moiety at the 8-position of the A ring.

Cysteine proteases as potential targets for anti-trypanosomatid drug discovery

Leishmaniasis and trypanosomiasis are endemic neglected disease in South America and Africa and considered a significant public health problem, mainly in poor communities. The limitations of the current available therapeutic options, including the lack of specificity, relatively high toxicity, and the drug resistance acquiring, drive the constant search for new targets and therapeutic options. Advances in knowledge of parasite biology have revealed essential enzymes involved in the replication, survival, and pathogenicity of Leishmania and Trypanosoma species. In this scenario, cysteine proteases have drawn the attention of researchers and they are being proposed as promising targets for drug discovery of antiprotozoal drugs. In this systematic review, we will provide an update on drug discovery strategies targeting the cysteine proteases as potential targets for chemotherapy against protozoal neglected diseases.

The Pseudomonas aeruginosa product pyochelin interferes with Trypanosoma cruzi infection and multiplication in vitro

BACKGROUND

Bacteria are sources of numerous molecules used in treatment of infectious diseases. We investigated effects of molecules produced by 26 Pseudomonas aeruginosa strains against infection of mammalian cell cultures with Trypanosoma cruzi, the aetiological agent of Chagas disease.

METHODS

Vero cells were infected with T. cruzi in the presence of wild-type P. aeruginosa supernatants or supernatants of mutants with defects in the production of various virulence, quorum sensing and iron acquisition factors. Quantification of T. cruzi infection (percentage of infected cells) and multiplication (number of amastigotes per infected cell) was performed and cell viability was determined.

RESULTS

Wild-type P. aeruginosa products negatively affected T. cruzi infection and multiplication in a dose-dependent manner, without evident toxicity for mammalian cells. PvdD/pchE mutation (loss of the P. aeruginosa siderophores pyoverdine and pyochelin) had the greatest impact on anti-T. cruzi activity. Negative effects on T. cruzi infection by pure pyochelin, but not pyoverdine, or other P. aeruginosa exoproducts studied, were quantitatively similar to the effects of benznidazole, the current standard therapy against T. cruzi.

CONCLUSIONS

The P. aeruginosa product pyochelin showed promising activity against T. cruzi and might become a new lead molecule for therapy development.

Nano Based Approach for the Treatment of Neglected Tropical Diseases

Neglected tropical diseases (NTDs) afflict more than one billion peoples in the world’s poorest countries. The World Health Organization (WHO) has recorded seventeen NTDs in its portfolio, mainly caused by bacterial, protozoal, parasitic, and viral infections. Each of the NTDs has its unique challenges on human health such as interventions for control, prevention, diagnosis, and treatment. Research for the development of new drug molecules against NTDs has not been undertaken by pharmaceutical industries due to high investment and low-returns, which results in limited chemotherapeutics in the market. In addition, conventional chemotherapies for the treatment of NTDs are unsatisfactory due to its low efficacy, increased drug resistance, short half-life, potential or harmful fatal toxic side effects, and drug incompetence to reach the site of parasite infection. In this context, active chemotherapies are considered to be re-formulated by overcoming these toxic side effects via a tissue-specific targeted drug delivery system. This review mainly emphasizes the recent developments of nanomaterial-based drug delivery systems for the effective treatment of NTDs especially sleeping sickness, leishmaniasis, chagas disease, soil-transmitted helminthiasis, african trypanosomiasis and dengue. Nanomaterials based drug delivery systems offer enhanced and effective alternative therapy through the re-formulation approach of conventional drugs into site-specific targeted delivery of drugs.

In vitro studies and preclinical evaluation of benznidazole microparticles in the acute Trypanosoma cruzi murine model

Chagas disease is a serious parasitic infection caused by Trypanosoma cruzi. Unfortunately, the current chemotherapeutic tools are not enough to combat the infection. The aim of this study was to evaluate the trypanocidal activity of benznidazole-loaded microparticles during the acute phase of Chagas infection in an experimental murine model. Microparticles were prepared by spray-drying using copolymers derived from esters of acrylic and methacrylic acids as carriers. Dissolution efficiency of the formulations was up to 3.80-fold greater than that of raw benznidazole. Stability assay showed no significant difference (P > 0.05) in the loading capacity of microparticles for 3 years. Cell cultures showed no visible morphological changes or destabilization of the cell membrane nor haemolysis was observed in defibrinated human blood after microparticles treatment. Mice with acute lethal infection survived 100% after 30 days of treatment with benznidazole microparticles (50 mg kg-1 day-1). Furthermore, no detectable parasite load measured by quantitative polymerase chain reaction and lower levels of T. cruzi-specific antibodies by enzyme-linked immunosorbent assay were found in those mice. A significant decrease in the inflammation of heart tissue after treatment with these microparticles was observed, in comparison with the inflammatory damage observed in both infected mice treated with raw benznidazole and untreated infected mice. Therefore, these polymeric formulations are an attractive approach to treat Chagas disease.

GC-MS Characterization of Antibacterial, Antioxidant, and Antitrypanosomal Activity of Syzygium aromaticum Essential Oil and Eugenol

Syzygium aromaticum has a diversity of biological activities due to the chemical compounds found in its plant products such as total phenolic compounds and flavonoids. The present work describes the chemical analysis and antimicrobial, antioxidant, and antitrypanosomal activity of the essential oil of S. aromaticum. Eugenol (53.23%) as the major compound was verified by gas chromatography-mass spectrometry. S. aromaticum essential oil was more effective against S. aureus (MIC 50 μg/mL) than eugenol (MIC 250 μg/mL). Eugenol presented higher antioxidant activity than S. aromaticum essential oil, with an EC₅₀ of 12.66 and 78.98 µg/mL, respectively. S. aromaticum essential oil and eugenol exhibited Trypanosoma cruzi inhibitory activity, with IC₅₀ of 28.68 ± 1.073 and 31.97 ± 1.061 μg/mL against epimastigotes and IC₅₀ of 64.51 ± 1.658 and 45.73 ± 1.252 μg/mL against intracellular amastigotes, respectively. Both compounds presented low cytotoxicity, with S. aromaticum essential oil displaying 15.5-fold greater selectivity for the parasite than the cells. Nitrite levels in T. cruzi-stimulated cells were reduced by essential oil (47.01%; p = 0.002) and eugenol (48.05%; p = 0.003) treatment. The trypanocidal activity of S. aromaticum essential oil showed that it is reasonable to use it in future research in the search for new therapeutic alternatives for trypanosomiasis.

Precision Health for Chagas Disease: Integrating Parasite and Host Factors to Predict Outcome of Infection and Response to Therapy

Chagas disease, caused by the infection with the protozoan parasite Trypanosoma cruzi, is clinically manifested in approximately one-third of infected people by inflammatory heart disease (cardiomyopathy) and, to a minor degree, gastrointestinal tract disorders (megaesophagus or megacolon). Chagas disease is a zoonosis transmitted among animals and people through the contact with triatomine bugs, which are found in much of the western hemisphere, including most countries of North, Central and South America, between parallels 45° north (Minneapolis, USA) and south (Chubut Province, Argentina). Despite much research on drug discovery for T. cruzi, there remain only two related agents in widespread use. Likewise, treatment is not always indicated due to the serious side effects of these drugs. On the other hand, the epidemiology and pathogenesis of Chagas disease are both highly complex, and much is known about both. However, it is still impossible to predict what will happen in an individual person infected with T. cruzi, because of the highly variability of parasite virulence and human susceptibility to infection, with no definitive molecular predictors of outcome from either side of the host-parasite equation. In this Minireview we briefly discuss the current state of T. cruzi infection and prognosis and look forward to the day when it will be possible to employ precision health to predict disease outcome and determine whether and when treatment of infection may be necessary.

Trypanocidal Effect of Nano MOFs-EP on Circulating Forms of Trypanosoma cruzi

BACKGROUND

Chagas disease caused by the parasite Trypanosoma cruzi is considered a neglected disease in several countries. One of the main problems about this disease is the lack of an effective treatment and the absence of adverse effects. T. cruzi, like most pathogenic fungi and yeasts, require specific sterols to maintain viability and proliferative capacity during their life cycle. However, the oxidation of this molecule to ergosterol peroxide has shown several biological effects, including its trypanocidal activity.

METHODS

We have synthesized MOFs nanoparticles as carrier system coupled to ergosterol peroxide (MOFs-EP) and we have studied its effect on the circulating forms of the T. cruzi parasite.

RESULTS

MOFs-EP possess an efficient trypanocidal activity at much lower inhibitory concentrations (ng/mL) that the concentrations shown by ergosterol peroxide (μg/mL) when administered unconjugated form.

CONCLUSION

Our results open a new possibility in the biomedical application of MOFs and ergosterol peroxide in the search for new options for the treatment of Chagas disease.

Detection of Trypanosoma cruzi by PCR in adults with chronic Chagas disease treated with nifurtimox

Chagas disease, a vector-borne parasitosis caused by Trypanosoma cruzi, is endemic to Latin America and has spread to other countries due to immigration of infected persons. It is estimated that 160,000 people are infected in Chile, most of them in the chronic phase and without etiological treatment. The infection is confirmed by conventional serological methods while molecular methods have become in valuable tools to evaluate parasitemia in treated and non-treated chronic Chagas disease patients. The objective of this study was to determine, by conventional Polymerase Chain Reaction, the presence of T. cruzi kinetoplastid DNA in peripheral blood samples from 114 adult individuals with confirmed chronic Chagas disease, before and 6.6 years (average) after treatment with nifurtimox. The samples were received and preserved in guanidine-EDTA until DNA purification. Conventional PCR assays were performed in triplicate with T. cruzi kinetoplastid DNA primers 121 and 122. The amplified products were fractionated by electrophoresis in 2% agarose gels. A 330 bp product represented a positive assay. 84.2% (96 cases) and 6.1% (7 cases) of the samples taken before and after the treatment, respectively, were positive. The McNemar test showed a statistically significant difference between the groups of samples (p<0.001). Since serological negativization (the current cure criterion) delay many years after therapy and positive parasitological results represent a treatment failure, the conversion of pre-therapy positive conventional PCR is a qualitative and complementary tool that could be included in protocols of prolonged follow-up.

A Combination of Itraconazole and Amiodarone Is Highly Effective against Trypanosoma cruzi Infection of Human Stem Cell-Derived Cardiomyocytes

Trypanosoma cruzi is the etiologic agent of Chagas disease (CD), which can result in severe cardiomyopathy. Trypanosoma cruzi is endemic to the Americas, and of particular importance in Latin America. In the United States and other non-endemic countries, rising case numbers have also been observed. The currently used drugs are benznidazole (BNZ) and nifurtimox, which have limited efficacy during chronic infection. We repurposed itraconazole (ICZ), originally an antifungal, in combination with amiodarone (AMD), an antiarrhythmic, with the goal of interfering with T. cruzi infection. Human pluripotent stem cells (hiPSCs) were differentiated into cardiomyocytes (hiPSC-CMs). Vero cells or hiPSC-CMs were infected with T. cruzi trypomastigotes of the II or I strain in the presence of ICZ and/or AMD. After 48 hours, cells were Giemsa stained, and infection and multiplication were evaluated microscopically. Trypanosoma cruzi infection and multiplication were evalutated also by electron microscopy. BNZ was used as a reference compound. Cell metabolism in the presence of test substances was assessed. Itraconazole and AMD showed strain- and dose-dependent interference with T. cruzi infection and multiplication in Vero cells or hiPSC-CMs. Combinations of ICZ and AMD were more effective against T. cruzi than the single substances, or BNZ, without affecting host cell metabolism, and better preserving host cell integrity during infection. Our in vitro data in hiPSC-CMs suggest that a combination of ICZ and AMD might serve as a treatment option for CD in patients, but that different responses due to T. cruzi strain differences have to be taken into account.

Development of a motion-based cell-counting system for Trypanosoma parasite using a pattern recognition approach

Automated cell counters that utilize still images of sample cells are widely used. However, they are not well suited to counting slender, aggregate-prone microorganisms such as Trypanosoma cruzi. Here, we developed a motion-based cell-counting system, using an image-recognition method based on a cubic higher-order local auto-correlation feature. The software successfully estimated the cell density of dispersed, aggregated, as well as fluorescent parasites by motion pattern recognition. Loss of parasites activeness due to drug treatment could also be detected as a reduction in apparent cell count, which potentially increases the sensitivity of drug screening assays. Moreover, the motion-based approach enabled estimation of the number of parasites in a co-culture with host mammalian cells, by disregarding the presence of the host cells as a static background.

Utilization of proliferable extracellular amastigotes for transient gene expression, drug sensitivity assay, and CRISPR/Cas9-mediated gene knockout in Trypanosoma cruzi

Trypanosoma cruzi has three distinct life cycle stages; epimastigote, trypomastigote, and amastigote. Amastigote is the replication stage in host mammalian cells, hence this stage of parasite has clinical significance in drug development research. Presence of extracellular amastigotes (EA) and their infection capability have been known for some decades. Here, we demonstrate that EA can be utilized as an axenic culture to aid in stage-specific study of T. cruzi. Amastigote-like property of axenic amastigote can be sustained in LIT medium at 37°C at least for 1 week, judging from their morphology, amastigote-specific UTR-regulated GFP expression, and stage-specific expression of selected endogenous genes. Inhibitory effect of benznidazole and nifurtimox on axenic amastigotes was comparable to that on intracellular amastigotes. Exogenous nucleic acids can be transfected into EA via conventional electroporation, and selective marker could be utilized for enrichment of transfectants. We also demonstrate that CRISPR/Cas9-mediated gene knockout can be performed in EA. Essentiality of the target gene can be evaluated by the growth capability of the knockout EA, either by continuation of axenic culturing or by host infection and following replication as intracellular amastigotes. By taking advantage of the accessibility and sturdiness of EA, we can potentially expand our experimental freedom in studying amastigote stage of T. cruzi.

In Silico Studies Designed to Select Sesquiterpene Lactones with Potential Antichagasic Activity from an In-House Asteraceae Database

Chagas disease is an endemic disease caused by Trypanosoma cruzi, which affects more than eight million people, mostly in the Americas. A search for new treatments is necessary to control and eliminate this disease. Sesquiterpene lactones (SLs) are an interesting group of secondary metabolites characteristic of the Asteraceae family that have presented a wide range of biological activities. From the ChEMBL database, we selected a diverse set of 4452, 1635, and 1322 structures with tested activity against the three T. cruzi parasitic forms: amastigote, trypomastigote, and epimastigote, respectively, to create random forest (RF) models with an accuracy of greater than 74 % for cross-validation and test sets. Afterward, a ligand-based virtual screen of the entire SLs of the Asteraceae database stored in SistematX (1306 structures) was performed. In addition, a structure-based virtual screen was also performed for the same set of SLs using molecular docking. Finally, using an approach combining ligand-based and structure-based virtual screening along with the equations proposed in this study to normalize the probability scores, we verified potentially active compounds and established a possible mechanism of action.

Experimental and Clinical Treatment of Chagas Disease: A Review

Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi that infects a broad range of triatomines and mammalian species, including man. It afflicts 8 million people in Latin America, and its incidence is increasing in nonendemic countries owing to rising international immigration and nonvectorial transmission routes such as blood donation. Since the 1960s, the only drugs available for the clinical treatment of this infection have been benznidazole (BZ) and nifurtimox (NFX). Treatment with these trypanocidal drugs is recommended in both the acute and chronic phases of CD. These drugs have low cure rates mainly during the chronic phase, in addition both drugs present side effects that may result in the interruption of the treatment. Thus, more efficient and better-tolerated new drugs or pharmaceutical formulations containing BZ or NFX are urgently needed. Here, we review the drugs currently used for CD chemotherapy, ongoing clinical assays, and most-promising new experimental drugs. In addition, the mechanism of action of the commercially available drugs, NFX and BZ, the biodistribution of the latter, and the potential for novel formulations of BZ based on nanotechnology are discussed. Taken together, the literature emphasizes the urgent need for new therapies for acute and chronic CD.

Pediatric enteric neuropathies: diagnosis and current management

PURPOSE OF REVIEW

Neurointestinal diseases are increasingly recognized as causes of significant gastrointestinal morbidity in children. This review highlights the most common pediatric enteric neuropathies and their diagnosis and management, emphasizing insights and discoveries from the most recent literature available.

RECENT FINDINGS

The embryologic and histopathologic causes of enteric neuropathies are varied. They range from congenital aganglionosis in Hirschsprung disease, to autoimmune-mediated loss of neuronal subtypes in esophageal achalasia and Chagas disease, to degenerative neuropathies in some cases of chronic intestinal pseudo-obstruction and gastroparesis. Increased awareness of the clinical presentation and diagnostic evaluation of these conditions is essential as it allows for earlier initiation of treatment and improved outcomes. Most current therapies, which include medical management, neurostimulation, and operative intervention, aim to minimize the symptoms caused by these conditions. The evidence base for many of these treatments in children is poor, and multiinstitutional prospective studies are needed. An innovative therapy on the horizon involves using neuronal stem cell transplantation to treat the underlying disorder by replacing the missing or damaged neurons in these diseases.

SUMMARY

Although recent advances in basic and clinical neurogastroenterology have significantly improved our awareness and understanding of enteric neuropathies, the efficacy of current treatment approaches is limited. The development of novel therapies, including pharmacologic modulators of neurointestinal function, neurostimulation to enhance gut motility, and neuronal cell-based therapies, is essential to improve the long-term outcomes in children with these disorders.

Nitrotriazole-Based Compounds as Antichagasic Agents in a Long-Treatment In Vivo Assay

3-Nitrotriazole-based compounds belonging to various chemical subclasses were found to be very effective against Chagas disease both in vitro and in vivo after a short administration schedule. In this study, five compounds with specific characteristics were selected to be administered for longer periods of time to mice infected with the virulent Trypanosoma cruzi Y strain to further evaluate their effectiveness as antichagasic agents and whether or not potential adverse effects occur. Benznidazole was included for comparison purposes. Complete parasitemia depletion, weight gain, 100% survival, and a lack of myocardial inflammation were observed with four of the compounds and benznidazole administered intraperitoneally at 15 or 20 mg/kg of body weight/day for 40 days. There was a significant reduction in the number of treatment days (number of doses) necessary to induce parasitemia suppression with all four compounds compared to that required with benznidazole. Partial cures were obtained with only one compound tested at 15 mg/kg/day and on the schedule mentioned above but not with benznidazole. Taken together, our data suggest that these compounds demonstrate potent trypanocidal activity comparable to or better than that of the reference drug, benznidazole, when they are administered at the same dose and on the same schedule.

Phenotypic evaluation and in silico ADMET properties of novel arylimidamides in acute mouse models of Trypanosoma cruzi infection

Arylimidamides (AIAs), previously termed as reversed amidines, present a broad spectrum of activity against intracellular microorganisms. In the present study, three novel AIAs were evaluated in a mouse model of Trypanosoma cruzi infection, which is the causative agent of Chagas disease. The bis-AIAs DB1957, DB1959 and DB1890 were chosen based on a previous screening of their scaffolds that revealed a very promising trypanocidal effect at nanomolar range against both the bloodstream trypomastigotes (BTs) and the intracellular forms of the parasite. This study focused on both mesylate salts DB1957 and DB1959 besides the hydrochloride salt DB1890. Our current data validate the high activity of these bis-AIA scaffolds that exhibited EC₅₀ (drug concentration that reduces 50% of the number of the treated parasites) values ranging from 14 to 78 nM and 190 to 1,090 nM against bloodstream and intracellular forms, respectively, also presenting reasonable selectivity indexes and no mutagenicity profile predicted by in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET). Acute toxicity studies using murine models revealed that these AIAs presented only mild toxic effects such as reversible abdominal contractions and ruffled fur. Efficacy assays performed with Swiss mice infected with the Y strain revealed that the administration of DB1957 for 5 consecutive days, with the first dose given at parasitemia onset, reduced the number of BTs at the peak, ranging between 21 and 31% of decrease. DB1957 was able to provide 100% of animal survival, while untreated animals showed 70% of mortality rates. DB1959 and DB1890B did not reduce circulating parasitism but yielded >80% of survival rates.

Computer-Aided Drug Design Using Sesquiterpene Lactones as Sources of New Structures with Potential Activity against Infectious Neglected Diseases

This review presents an survey to the biological importance of sesquiterpene lactones (SLs) in the fight against four infectious neglected tropical diseases (NTDs)—leishmaniasis, schistosomiasis, Chagas disease, and sleeping sickness—as alternatives to the current chemotherapies that display several problems such as low effectiveness, resistance, and high toxicity. Several studies have demonstrated the great potential of some SLs as therapeutic agents for these NTDs and the relationship between the protozoal activities with their chemical structure. Recently, Computer-Aided Drug Design (CADD) studies have helped increase the knowledge of SLs regarding their mechanisms, the discovery of new lead molecules, the identification of pharmacophore groups and increase the biological activity by employing in silico tools such as molecular docking, virtual screening and Quantitative-Structure Activity Relationship (QSAR) studies.

The Trypanosoma cruzi Diamine Transporter Is Essential for Robust Infection of Mammalian Cells

Trypanosoma cruzi is incapable of synthesizing putrescine or cadaverine de novo, and, therefore, salvage of polyamines from the host milieu is an obligatory nutritional function for the parasite. A high-affinity diamine transporter (TcPOT1) from T. cruzi has been identified previously that recognizes both putrescine and cadaverine as ligands. In order to assess the functional role of TcPOT1 in intact parasites, a Δtcpot1 null mutant was constructed by targeted gene replacement and characterized. The Δtcpot1 mutant lacked high-affinity putrescine-cadaverine transport capability but retained the capacity to transport diamines via a non-saturable, low-affinity mechanism. Transport of spermidine and arginine was not impacted by the Δtcpot1 lesion. The Δtcpot1 cell line exhibited a significant but not total defect in its ability to subsist in Vero cells, although initial infection rates were not affected by the lesion. These findings reveal that TcPOT1 is the sole high-affinity diamine permease in T. cruzi, that genetic obliteration of TcPOT1 impairs the ability of the parasite to maintain a robust infection in mammalian cells, and that a secondary low-affinity uptake mechanism for this key parasite nutrient is operative but insufficient for optimal infection.

Synthesis and Evaluation of Oxyguanidine Analogues of the Cysteine Protease Inhibitor WRR-483 against Cruzain

A series of oxyguanidine analogues of the cysteine protease inhibitor WRR-483 were synthesized and evaluated against cruzain, the major cysteine protease of the protozoan parasite Trypanosoma cruzi. Kinetic analyses of these analogues indicated that they have comparable potency to previously prepared vinyl sulfone cruzain inhibitors. Co-crystal structures of the oxyguanidine analogues WRR-666 (4) and WRR-669 (7) bound to cruzain demonstrated different binding interactions with the cysteine protease, depending on the aryl moiety of the P1' inhibitor subunit. Specifically, these data demonstrate that WRR-669 is bound noncovalently in the crystal structure. This represents a rare example of noncovalent inhibition of a cysteine protease by a vinyl sulfone inhibitor.

Medicinal organometallic compounds with anti-chagasic activity

Chagas disease (CD) is one of the most important neglected tropical disorders, being a major health concern in Latin America.

Clinical Candidate VT-1161's Antiparasitic Effect In Vitro, Activity in a Murine Model of Chagas Disease, and Structural Characterization in Complex with the Target Enzyme CYP51 from Trypanosoma cruzi

A novel antifungal drug candidate, the 1-tetrazole-based agent VT-1161 [(R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(1H-tetrazol-1-yl)-1-{5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl}propan-2-ol], which is currently in two phase 2b antifungal clinical trials, was found to be a tight-binding ligand (apparent dissociation constant [Kd], 24 nM) and a potent inhibitor of cytochrome P450 sterol 14α-demethylase (CYP51) from the protozoan pathogen Trypanosoma cruzi. Moreover, VT-1161 revealed a high level of antiparasitic activity against amastigotes of the Tulahuen strain of T. cruzi in cellular experiments (50% effective concentration, 2.5 nM) and was active in vivo, causing >99.8% suppression of peak parasitemia in a mouse model of infection with the naturally drug-resistant Y strain of the parasite. The data strongly support the potential utility of VT-1161 in the treatment of Chagas disease. The structural characterization of T. cruzi CYP51 in complex with VT-1161 provides insights into the molecular basis for the compound's inhibitory potency and paves the way for the further rational development of this novel, tetrazole-based inhibitory chemotype both for antiprotozoan chemotherapy and for antifungal chemotherapy.

Development of a Fluorescence-based Trypanosoma cruzi CYP51 Inhibition Assay for Effective Compound Triaging in Drug Discovery Programmes for Chagas Disease

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi (T. cruzi), is a life threatening global health problem with only two drugs available for treatment (benznidazole and nifurtimox), both having variable efficacy in the chronic stage of the disease and high rates of adverse drug reactions. Inhibitors of sterol 14α-demethylase (CYP51) have proven effective against T. cruzi in vitro and in vivo in animal models of Chagas disease. Consequently two azole inhibitors of CYP51 (posaconazole and ravuconazole) have recently entered clinical development by the Drugs for Neglected Diseases initiative. Further new drug treatments for this disease are however still urgently required, particularly having a different mode of action to CYP51 in order to balance the overall risk in the drug discovery portfolio. This need has now been further strengthened by the very recent reports of treatment failure in the clinic for both posaconazole and ravuconazole. To this end and to prevent enrichment of drug candidates against a single target, there is a clear need for a robust high throughput assay for CYP51 inhibition in order to evaluate compounds active against T. cruzi arising from phenotypic screens. A high throughput fluorescence based functional assay using recombinantly expressed T. cruzi CYP51 (Tulahuen strain) is presented here that meets this requirement. This assay has proved valuable in prioritising medicinal chemistry resource on only those T. cruzi active series arising from a phenotypic screening campaign where it is clear that the predominant mode of action is likely not via inhibition of CYP51.

Chagas disease, caused by the parasite Trypanosoma cruzi (T. cruzi), is endemic in Latin America and emerging in North America and Europe through human migration. It is a severe global health problem with 8–10 million people infected and an estimated 12,000 deaths annually. Current treatment options are poorly efficacious and have severe side effects. New drugs are therefore urgently required. Two of these potential new drugs, posaconazole and ravuconazole, both targeting an enzyme in T. cruzi called CYP51, have recently failed in clinical development. Therefore, in light of these recent clinical failures and in order to better balance the overall risk in the drug discovery portfolio for Chagas disease, it has become prudent to assess whether new chemical start points for drug discovery programmes have a mode of action predominantly driven by T. cruzi CYP51 inhibition. In this paper we report a fluorescence based assay to determine whether compounds inhibit T. cruzi CYP51. This provides a high throughput screen to help prioritise medicinal chemistry resource on those T. cruzi active new chemical series that do not have a mode of action predominantly driven by CYP51 inhibition.

Translational challenges of animal models in Chagas disease drug development: a review

Chagas disease, or American trypanosomiasis, caused by Trypanosoma cruzi parasite infection is endemic in Latin America and presents an increasing clinical challenge due to migrating populations. Despite being first identified over a century ago, only two drugs are available for its treatment, and recent outcomes from the first clinical trials in 40 years were lackluster. There is a critical need to develop new drugs to treat Chagas disease. This requires a better understanding of the progression of parasite infection, and standardization of animal models designed for Chagas disease drug discovery. Such measures would improve comparison of generated data and the predictability of test hypotheses and models designed for translation to human disease. Existing animal models address both disease pathology and treatment efficacy. Available models have limited predictive value for the preclinical evaluation of novel therapies and need to more confidently predict the efficacy of new drug candidates in clinical trials. This review highlights the overall lack of standardized methodology and assessment tools, which has hampered the development of efficacious compounds to treat Chagas disease. We provide an overview of animal models for Chagas disease, and propose steps that could be undertaken to reduce variability and improve predictability of drug candidate efficacy. New technological developments and tools may contribute to a much needed boost in the drug discovery process.

Mother-to-Child Transmission of Chagas Disease in El Salvador

To estimate the incidence (any mother to child) and rate (from seropositive mother to child) of mother-to-child transmission of Trypanosoma cruzi, a serological census was conducted, targeting pregnant women and infants born to seropositive mothers, in four municipalities of El Salvador. Of 943 pregnant women, 36 (3.8%) were seropositive for T. cruzi. Of 36, 32 proceeded to serological tests of their infants when they became 6-8 months of age. Six infants seropositive at the age of 6-8 months further proceeded to second-stage serological test at the age of 9-16 months. As the result, one infant was congenitally infected. Thus, serological tests at the age of 6-8 months produced five false positives. To ensure earlier effective medication only for true positives, identification of seropositive infants at the age of 9-16 months is crucial. Incidence and rate of mother-to-child transmission were 0.14 (per 100 person-years) and 4.0%, respectively. Estimated number of children infected through mother-to-child transmission in El Salvador (170 per year) was much higher than that of human immunodeficiency virus (HIV; seven per year). It is recommended that serological testing for T. cruzi be integrated into those for HIV and syphilis as part of antenatal care package.

cAMP signalling in trypanosomatids: role in pathogenesis and as a drug target

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Trypanosoma brucei adenylate cyclases are implicated in modulation of host immune response and social motility.

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First effectors downstream of cAMP signalling were identified in Trypanosoma cruzi and T. brucei.

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Crystal structures reveal a unique pocket in trypanosomatid phosphodiesterases.

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Trypanosomatid phosphodiesterase inhibitors are promising drug candidates.

Despite recent research linking cAMP signalling to virulence in trypanosomatids and detailed studies of trypanosomatid adenylyl cyclases (ACs) and phosphodiesterases (PDEs) since their discoveries 40 years ago, downstream components of the pathway and their biological functions have remained remarkably elusive. However, in recent years, significant discoveries have been made: a role for parasite ACs has been proposed in cytokinesis, evasion of the host immune response, and social motility. cAMP phosphodiesterases PDEB1 and PDEB2 were found to be essential for survival and virulence of Trypanosoma brucei and, in Trypanosoma cruzi, PDEC2 was shown to be required for normal osmoregulation. As we discuss here, these breakthroughs have led to an ongoing surge in the development of PDE inhibitors as lead compounds for trypanocidal drugs.

Structural insights of SIR2rp3 proteins as promising biotargets to fight against Chagas disease and leishmaniasis

Trypanosoma cruzi and Leishmania spp. are protozoan pathogens responsible for Chagas disease and leishmaniasis, respectively. Current therapies rely only on a very small number of drugs, most of them are inadequate because of their severe host toxicity or drug-resistance phenomena. In order to find therapeutic alternatives, the identification of new biotargets is highly desired. In this study, homology modelling, docking and molecular dynamics simulations have been used to generate robust 3D models of NAD(+)-dependent deacetylases from Trypanosoma and Leishmania spp., known as SIR2rp3, whose structures have never been described before. Molecular docking of known inhibitors revealed strong analogies with the mitochondrial human SIRT5 in terms of binding mode and interaction strength. On the other hand, by extending the analysis to the channel rims, regions of difference between host and parasitic targets, useful for future selective drug design projects, were pointed out.

Benznidazole modulates cell proliferation in acute leukemia cells

CONTEXT

We have previously reported that benznidazole (BZL), known for its trypanocidal action, has anti-proliferative activity against different cell lines like HeLa and Raw 264.7 among others. At the moment, it has not been reported if the anti-proliferative effect of BZL is similar for non-adherent hematopoietic cells like was reported for adherent cancer cell lines.

OBJECTIVE

We aimed to investigate the efficacy of BZL on the growth of the leukemic cell lines THP-1 and OCI/AML3.

MATERIALS AND METHODS

We evaluated cell proliferation by [³H]-thymidine incorporation and MTT reduction as well as cell death by lactate dehydrogenase (LDH) activity. We assessed apoptosis by flow cytometry for detection of annexin V-positive and propidium iodide-negative cells, along with nuclear morphology by diamidino-2-phenolindole (DAPI) staining. Western blot studies were performed to evaluate changes in cell cycle proteins in BZL-treated cells.

RESULTS

BZL significantly reduced proliferation of both cell lines without inducing cell death. Likewise it produced no significant differences in apoptosis between treated cells and controls. In addition, flow cytometry analysis indicated that BZL caused a larger number of THP-1 cells in G0/G1 phase and a smaller number of cells in S phase than controls. This was accompanied with an increase in the expression of the CDK inhibitor p27 and of cyclin D1, with no significant differences in the protein levels of CDK1, CDK2, CDK4, cyclins E, A and B as compared to controls.

CONCLUSION

BZL inhibits the proliferation of leukemic non-adherent cells by controlling cell cycle at G0/G1 cell phase through up-regulation of p27.

Structure-dependent binding of arylimidamides to the DNA minor groove

Heterocyclic diamidines are strong DNA minor-groove binders and have excellent antiparasitic activity. To extend the biological activity of these compounds, a series of arylimidamides (AIAs) analogues, which have better uptake properties in Leishmania and Trypanosoma cruizi than diamidines, was prepared. The binding of the AIAs to DNA was investigated by Tm , fluorescence displacement titration, circular dichroism, DNase I footprinting, biosensor surface plasmon resonance, X-ray crystallography and molecular modeling. These compounds form 1:1 complexes with AT sequences in the DNA minor groove, and the binding strength varies with substituent size, charge and polarity. These substituent-dependent structure and properties provide a SAR that can be used to estimate K values for binding to DNA in this series. The structural results and molecular modeling studies provide an explanation for the differences in binding affinities for AIAs.

Reversible cysteine protease inhibitors show promise for a Chagas disease cure

The cysteine protease cruzipain is essential for the viability, infectivity, and virulence of Trypanosoma cruzi, the causative agent of Chagas disease. Thus, inhibitors of cruzipain are considered promising anti-T. cruzi chemotherapeutic agents. Reversible cruzipain inhibitors containing a nitrile "warhead" were prepared and demonstrated 50% inhibitory concentrations (IC50s) as potent as 1 nM in baculovirus-generated cruzipain enzyme assays. In epimastigote and intracellular amastigote in vitro assays, the most potent compounds demonstrated antiparasitic behavior in the 5 to 10 μM IC50 range; however, trypomastigote production from the amastigote form was ∼90 to 95% inhibited at 2 μM. Two key compounds, Cz007 and Cz008, with IC50s of 1.1 and 1.8 nM, respectively, against the recombinant enzyme were tested in a murine model of acute T. cruzi infection, with oral dosing in chow for 28 days at doses from 3 to 50 mg/kg of body weight. At 3 mg/kg of Cz007 and 3 mg/kg of Cz008, the blood parasitemia areas under the concentration-time curves were 16% and 25% of the untreated group, respectively. At sacrifice, 24 days after immunosuppression with cyclophosphamide, parasite presence in blood, heart, and esophagus was evaluated. Based on negative quantitative PCR results in all three tissues, cure rates in surviving animals were 90% for Cz007 at 3 mg/kg, 78% for Cz008 at 3 mg/kg, and 71% for benznidazole, the control compound, at 50 mg/kg.

Endothelial transmigration by Trypanosoma cruzi

Chagas heart disease, the leading cause of heart failure in Latin America, results from infection with the parasite Trypanosoma cruzi. Although T. cruzi disseminates intravascularly, how the parasite contends with the endothelial barrier to escape the bloodstream and infect tissues has not been described. Understanding the interaction between T. cruzi and the vascular endothelium, likely a key step in parasite dissemination, could inform future therapies to interrupt disease pathogenesis. We adapted systems useful in the study of leukocyte transmigration to investigate both the occurrence of parasite transmigration and its determinants in vitro. Here we provide the first evidence that T. cruzi can rapidly migrate across endothelial cells by a mechanism that is distinct from productive infection and does not disrupt monolayer integrity or alter permeability. Our results show that this process is facilitated by a known modulator of cellular infection and vascular permeability, bradykinin, and can be augmented by the chemokine CCL2. These represent novel findings in our understanding of parasite dissemination, and may help identify new therapeutic strategies to limit the dissemination of the parasite.

Trypanocidal activity of marine natural products

Marine natural products are a diverse, unique collection of compounds with immense therapeutic potential. This has resulted in these molecules being evaluated for a number of different disease indications including the neglected protozoan diseases, human African trypanosomiasis and Chagas disease, for which very few drugs are currently available. This article will review the marine natural products for which activity against the kinetoplastid parasites; Trypanosoma brucei brucei, T.b. rhodesiense and T. cruzi has been reported. As it is important to know the selectivity of a compound when evaluating its trypanocidal activity, this article will only cover molecules which have simultaneously been tested for cytotoxicity against a mammalian cell line. Compounds have been grouped according to their chemical structure and representative examples from each class were selected for detailed discussion.

Rational development of 4-aminopyridyl-based inhibitors targeting Trypanosoma cruzi CYP51 as anti-chagas agents

A new series of 4-aminopyridyl-based lead inhibitors targeting Trypanosoma cruzi CYP51 (TcCYP51) has been developed using structure-based drug design as well as structure-property relationship (SPR) analyses. The screening hit starting point, LP10 (KD ≤ 42 nM; EC50 = 0.65 μM), has been optimized to give the potential leads 14t, 27i, 27q, 27r, and 27t, which have low-nanomolar binding affinity to TcCYP51 and significant activity against T. cruzi amastigotes cultured in human myoblasts (EC50 = 14-18 nM for 27i and 27r). Many of the optimized compounds have improved microsome stability, and most are selective against human CYPs 1A2, 2D6, and 3A4 (<50% inhibition at 1 μM). A rationale for the improvement in microsome stability and selectivity of inhibitors against human metabolic CYP enzymes is presented. In addition, the binding mode of 14t with the Trypanosoma brucei CYP51 (TbCYP51) orthologue has been characterized by X-ray structure analysis.

Evaluation of nifurtimox treatment of chronic Chagas disease by means of several parasitological methods

Currently, evaluation of drug efficacy for Chagas disease remains a controversial issue with no consensus. In this work, we evaluated the parasitological efficacy of Nifurtimox treatment in 21 women with chronic Chagas disease from an area of endemicity in Chile who were treated according to current protocols. Under pre- and posttherapy conditions, blood (B) samples and xenodiagnosis (XD) samples from these patients were subjected to analysis by real-time PCR targeting the nuclear satellite DNA of Trypanosoma cruzi (Sat DNA PCR-B, Sat DNA PCR-XD) and by PCR targeting the minicircle of kinetoplast DNA of T. cruzi (kDNA PCR-B, kDNA PCR-XD) and by T. cruzi genotyping using hybridization minicircle tests in blood and fecal samples of Triatoma infestans feed by XD. In pretherapy, kDNA PCR-B and kDNA PCR-XD detected T. cruzi in 12 (57%) and 18 (86%) cases, respectively, whereas Sat DNA quantitative PCR-B (qPCR-B) and Sat DNA qPCR-XD were positive in 18 cases (86%) each. Regarding T. cruzi genotype analysis, it was possible to observe in pretherapy the combination of TcI, TcII, and TcV lineages, including mixtures of T. cruzi strains in most of the cases. At 13 months posttherapy, T. cruzi DNA was detectable in 6 cases (29.6%) and 4 cases (19.1%) by means of Sat DNA PCR-XD and kDNA PCR-XD, respectively, indicating treatment failure with recovery of live parasites refractory to chemotherapy. In 3 cases, it was possible to identify persistence of the baseline genotypes. The remaining 15 baseline PCR-positive cases gave negative results by all molecular and parasitological methods at 13 months posttreatment, suggesting parasite response. Within this follow-up period, kDNA PCR-XD and Sat DNA qPCR-XD proved to be more sensitive tools for the parasitological evaluation of the efficacy of Nifurtimox treatment than the corresponding PCR methods performed directly from blood samples.

Treatment of Chagas' disease with itraconazole: electrocardiographic and parasitological conditions after 20 years of follow-up

OBJECTIVES

To evaluate cases of chronic Chagas' disease for the long-term effects of treatment with itraconazole on Trypanosoma cruzi infections and the regression or development of ECG abnormalities.

METHODS

In March 1992, we treated 46 patients with chronic Chagas' disease with 6 mg/kg/day of itraconazole for 120 days in a blind evaluation. The patients came from an area of Chile where the disease was endemic and were checked for ECG abnormalities and with xenodiagnosis (XD) or real-time XD-quantitative PCR (XD-qPCR) for Trypanosoma cruzi infection before treatment and once a year for 20 years.

RESULTS

Twenty-one patients proved to be uninfected after 20 years and 15 of the patients had a normal ECG. Of the latter cases, 32.6% could be considered cured, although all of them had positive serology. Itraconazole prevents the development of ECG abnormalities, because after 20 years of treatment only 10.86% of patients developed ECG abnormalities (Z = 1.70, P = 0.046). XD-qPCR performed on 16 patients demonstrated 10 cases with <1.42 parasites/mL: eight with <1 parasite/mL, one with 1.42 parasites/mL and one with 1.01 parasites/mL. Five patients had more than 11.75 parasites/mL, all of them with a positive XD; these cases correspond to therapy failure, since re-infection was ruled out. In one case, XD-qPCR did not present amplification.

CONCLUSIONS

Itraconazole is useful in the treatment of chronic Chagas' disease as it prevented the development of ECG abnormalities and cured 32.6% of patients.

The absence of myocardial calcium-independent phospholipase A2γ results in impaired prostaglandin E2 production and decreased survival in mice with acute Trypanosoma cruzi infection

Cardiomyopathy is a serious complication of Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi. The parasite often infects cardiac myocytes, causing the release of inflammatory mediators, including eicosanoids. A recent study from our laboratory demonstrated that calcium-independent phospholipase A2γ (iPLA2γ) accounts for the majority of PLA2 activity in rabbit ventricular myocytes and is responsible for arachidonic acid (AA) and prostaglandin E2 (PGE2) release. Thus, we hypothesized that cardiac iPLA2γ contributes to eicosanoid production in T. cruzi infection. Inhibition of the isoform iPLA2γ or iPLA2β, with the R or S enantiomer of bromoenol lactone (BEL), respectively, demonstrated that iPLA2γ is the predominant isoform in immortalized mouse cardiac myocytes (HL-1 cells). Stimulation of HL-1 cells with thrombin, a serine protease associated with microthrombus formation in Chagas' disease and a known activator of iPLA2, increased AA and PGE2 release, accompanied by platelet-activating factor (PAF) production. Similarly, T. cruzi infection resulted in increased AA and PGE2 release over time that was inhibited by pretreatment with (R)-BEL. Further, T. cruzi-infected iPLA2γ-knockout (KO) mice had lower survival rates and increased tissue parasitism compared to wild-type (WT) mice, suggesting that iPLA2γ-KO mice were more susceptible to infection than WT mice. A significant increase in iPLA2 activity was observed in WT mice following infection, whereas iPLA2γ-KO mice showed no alteration in cardiac iPLA2 activity and produced less PGE2. In summary, these studies demonstrate that T. cruzi infection activates cardiac myocyte iPLA2γ, resulting in increased AA and PGE2 release, mediators that may be essential for host survival during acute infection. Thus, these studies suggest that iPLA2γ plays a cardioprotective role during the acute stage of Chagas' disease.

American trypanosomiasis

American trypanosomiasis is a parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is endemic in Latin America, where an estimated 10-14 million people are infected, and an emerging disease in Europe and the USA. Trypanosoma cruzi is transmitted by blood-sucking bugs of the family Reduviidae. Rhodnius prolixus, Panstrongylus megistus, Triatoma infestans, and T. dimidiata are the main vectors in the sylvatic cycle. Non vector-borne transmission includes blood transfusion, congenital and oral transmission, transplantation, and accidental infections. Most cases of acute infection occur in childhood and are usually asymptomatic, although severe myocarditis and meningoencephalitis may occur. Approximately 30% of T. cruzi-infected people will develop the chronic stage of the disease. Chronic chagasic cardiomyopathy is characterized by progressive heart failure, arrhythmias, intraventricular conduction defects, sudden death, and peripheral thromboembolism. Acute exacerbation can occur in individuals with involvement of cellular immunity such as advanced AIDS (acquired immunodeficiency syndrome), and transplant-associated immunosuppression. Neurological involvement may present with encephalitis, meningoencephalitis, or a space-occupying cerebral lesion called chagoma. Chagas disease is a major cause of ischemic stroke in Latin America. Several epidemiological studies have found an association between T. cruzi infection and cardioembolic ischemic stroke. Benznidazole and nifurtimox are the two available trypanocide drugs against T. cruzi.

Organocatalytic, enantioselective synthesis of VNI: a robust therapeutic development platform for Chagas, a neglected tropical disease

VNI is a potent inhibitor of CYP51 and was recently shown to achieve a parasitological cure of mice infected with T. cruzi in both acute and chronic stages of infection. T. cruzi is the causative parasite of Chagas disease, a neglected tropical disease. The first enantioselective chemical synthesis of VNI (at a materials cost of less than $0.10/mg) is described. Furthermore, the key enantioselective step is performed at the 10 g scale.

Congenital infection by Trypanosoma cruzi in an endemic area of Chile: a multidisciplinary study

BACKGROUND

This study investigated the prevalence of Chagas disease (ChD) in pregnant women in Choapa Province (IV Region, Chile) and the vertical transmission of Trypanosoma cruzi.

METHOD

ELISA and IFI IgG for ChD was performed for the pregnant women. PCR for T. cruzi was done for all chagasic mothers and their newborns. The congenital infection was confirmed by serial positive PCR and/or ELISA or IFI IgG after age of nine months. The placentas of mothers, with and without ChD, were submitted for histopathology and immunohistochemical study.

RESULTS

From 4831 deliveries in 2005-2009 with a serological coverage of 88.6%, it was established that 147 cases (3.4%) had ChD. More than 80% of the pregnancies had a physiological evolution and 90% of the newborn were term. Congenital transmission was demonstrated in six children (4.7%) of the 127 newborn studied by serial PCR (at birth and/or between 3-18 months) and/or ELISA or IIF IgG after age nine months. Most of congenital cases were asymptomatic (67%). The histopathology shows edema, necrosis, fibrinoid deposit in the placentas of 28 of 29 chagasic mothers. In three cases the immnunochemistry demonstrated a decrease in actin expression in trophoblast cells. In one congenital case amastigote nests was observed.

CONCLUSIONS

These results indicate that T. cruzi infection in pregnant women and vertical transmission in Chile are still prevalent. For this reason it is important to propose control measures in endemic areas of the country.