Benznidazole prevents endothelial damage in an experimental model of Chagas disease

Effect of statins on inflammation and cardiac function in patients with chronic Chagas disease: A protocol for pathophysiological studies in a multicenter, placebo-controlled, proof-of-concept phase II trial

BACKGROUND

Cardiac complications, including heart failure and arrhythmias, are the leading causes of disability and death in Chagas disease (CD). CD, caused by the Trypanosoma cruzi parasite, afflicts 7 million people in Latin America, and its incidence is increasing in non-endemic countries due to migration. The cardiac involvement is explained by parasite-dependent, immune-mediated myocardial injury, microvascular abnormalities, and ischemia. Current treatment of early CD includes the administration of nifurtimox and benznidazole. However, their efficacy is low in the chronic phase and may induce severe adverse events, forcing therapy to halt. Therefore, finding innovative approaches to treat this life-threatening tropical disease is of utmost importance. Thus, improving the efficacy of the current antichagasic drugs by modifying the inflammatory response would render the current treatment more effective. It has been reported that, in mice, simvastatin decreases cardiac inflammation and endothelial activation, and improves cardiac function, effects that require clinical confirmation.

OBJECTIVE

The study aims to analyze whether two doses of Atorvastatin, administered after CD treatment is completed, are safe and more efficacious than the antiparasitic drugs alone in reducing general inflammation and improving endothelial and cardiac functions in a proof-of-concept, placebo-controlled phase II trial.

METHODS

300 subjects will be recruited from four Chilean hospitals with an active Program for the Control of Chagas Disease. 40 or 80 mg/day of atorvastatin or placebo will be administered after completion of the antichagasic therapy. The patients will be followed up for 12 months. Efficacy will be determined by measuring changes in plasma levels of anti-inflammatory and pro-inflammatory cytokines, soluble cell adhesion molecules, BNP, and cTnT. Also, the resting 12-lead ECG and a 2D-echocardiogram will be obtained to evaluate cardiac function.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04984616.

Comparing in vivo bioluminescence imaging and the Multi-Cruzi immunoassay platform to develop improved Chagas disease diagnostic procedures and biomarkers for monitoring parasitological cure

BACKGROUND

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and is a serious public health problem throughout Latin America. With 6 million people infected, there is a major international effort to develop new drugs. In the chronic phase of the disease, the parasite burden is extremely low, infections are highly focal at a tissue/organ level, and bloodstream parasites are only intermittently detectable. As a result, clinical trials are constrained by difficulties associated with determining parasitological cure. Even highly sensitive PCR methodologies can be unreliable, with a tendency to produce "false-cure" readouts. Improved diagnostic techniques and biomarkers for cure are therefore an important medical need.

METHODOLOGY/PRINCIPAL FINDINGS

Using an experimental mouse model, we have combined a multiplex assay system and highly sensitive bioluminescence imaging to evaluate serological procedures for diagnosis of T. cruzi infections and confirmation of parasitological cure. We identified a set of three antigens that in the context of the multiplex serology system, provide a rapid, reactive and highly accurate read-out of both acute and chronic T. cruzi infection. In addition, we describe specific antibody responses where down-regulation can be correlated with benznidazole-mediated parasite reduction and others where upregulation is associated with persistent infection. One specific antibody (IBAG39) highly correlated with the bioluminescence flux and represents a promising therapy monitoring biomarker in mice.

CONCLUSIONS/SIGNIFICANCE

Robust, high-throughput methodologies for monitoring the efficacy of anti-T. cruzi drug treatment are urgently required. Using our experimental systems, we have identified markers of infection or parasite reduction that merit assessing in a clinical setting for the longitudinal monitoring of drug-treated patients.

Involvement of Inflammation and Its Resolution in Disease and Therapeutics

Inflammation plays a critical role in the response to and survival from injuries and/or infections. It occurs in two phases: initiation and resolution; however, when these events do not resolve and persist over time, the inflammatory response becomes chronic, prompting diseases that affect several systems and organs, such as the vasculature and the skin. Here, we reviewed inflammation that occurs in selected infectious and sterile pathologies. Thus, the immune processes induced by bacterial sepsis as well as T. cruzi and SARS-CoV-2 infections are shown. In addition, vaccine adjuvants as well as atherosclerosis are revised as examples of sterile-mediated inflammation. An example of the consequences of a lack of inflammation resolution is given through the revision of wound healing and chronic wounds. Then, we revised the resolution of the latter through advanced therapies represented by cell therapy and tissue engineering approaches, showing how they contribute to control chronic inflammation and therefore wound healing. Finally, new pharmacological insights into the management of chronic inflammation addressing the resolution of inflammation based on pro-resolving mediators, such as lipoxin, maresin, and resolvins, examining their biosynthesis, biological properties, and pharmacokinetic and pharmaceuticals limitations, are given. We conclude that resolution pharmacology and advanced therapies are promising tools to restore the inflammation homeostasis.

Vaccine-linked chemotherapy with a low dose of benznidazole plus a bivalent recombinant protein vaccine prevents the development of cardiac fibrosis caused by Trypanosoma cruzi in chronically-infected BALB/c mice

Background

Chagas disease (CD) is caused by Trypanosoma cruzi and affects 6–7 million people worldwide. Approximately 30% of chronic patients develop chronic chagasic cardiomyopathy (CCC) after decades. Benznidazole (BNZ), one of the first-line chemotherapy used for CD, induces toxicity and fails to halt the progression of CCC in chronic patients. The recombinant parasite-derived antigens, including Tc24, Tc24-C4, TSA-1, and TSA-1-C4 with Toll-like receptor 4 (TLR-4) agonist-adjuvants reduce cardiac parasite burdens, heart inflammation, and fibrosis, leading us to envision their use as immunotherapy together with BNZ. Given genetic immunization (DNA vaccines) encoding Tc24 and TSA-1 induce protective immunity in mice and dogs, we propose that immunization with the corresponding recombinant proteins offers an alternative and feasible strategy to develop these antigens as a bivalent human vaccine. We hypothesized that a low dose of BNZ in combination with a therapeutic vaccine (TSA-1-C4 and Tc24-C4 antigens formulated with a synthetic TLR-4 agonist-adjuvant, E6020-SE) given during early chronic infection, could prevent cardiac disease progression and provide antigen-specific T cell immunity.

Methodology/ Principal findings

We evaluated the therapeutic vaccine candidate plus BNZ (25 mg/kg/day/7 days) given on days 72 and 79 post-infection (p.i) (early chronic phase). Fibrosis, inflammation, and parasite burden were quantified in heart tissue at day 200 p.i. (late chronic phase). Further, spleen cells were collected to evaluate antigen-specific CD4⁺ and CD8⁺ T cell immune response, using flow cytometry. We found that vaccine-linked BNZ treated mice had lower cardiac fibrosis compared to the infected untreated control group. Moreover, cells from mice that received the immunotherapy had higher stimulation index of antigen-specific CD8⁺Perforin⁺ T cells as well as antigen-specific central memory T cells compared to the infected untreated control.

Conclusions

Our results suggest that the bivalent immunotherapy together with BNZ treatment given during early chronic infection protects BALB/c mice against cardiac fibrosis progression and activates a strong CD8⁺ T cell response by in vitro restimulation, evidencing the induction of a long-lasting T. cruzi-immunity.

Chagas disease (CD) is a neglected tropical disease caused by the parasite Trypanosoma cruzi, transmitted through contact with infected feces of vectors bugs. CD can induce cardiac abnormalities including the development of fibrosis and eventually death. Benznidazole (BNZ) is the first-line drug approved against CD, however, its toxicity and lack of efficacy in the chronic phase have limited its use. Previous studies have demonstrated the feasibility of reducing doses of BNZ given in combination with therapeutic vaccines during the acute phase of CD, which increases its tolerability and reduces adverse side effects. Considering that patients are often diagnosed until more advanced stages of the disease, its necessary to evaluate therapies given in the chronic phase of CD. In this study, we evaluated a vaccine formulated with the recombinant T. cruzi-antigens TSA-1-C4 and Tc24-C4 and the adjuvant E6020-SE in combination with a low dose of BNZ given during the chronic phase of T. cruzi-infection using a murine model. The authors found that the combination therapy protects mice against cardiac fibrosis progression, allows the activation of a CD8⁺ T cell response, and induces a prolonged memory response against T. cruzi. This study supports the development of the vaccine-linked chemotherapy approach to prevent T. cruzi chronic infection.

The role of vascular endothelium and exosomes in human protozoan parasitic diseases

The vascular endothelium is a vital component in maintaining the structure and function of blood vessels. The endothelial cells (ECs) mediate vital regulatory functions such as the proliferation of cells, permeability of various tissue membranes, and exchange of gases, thrombolysis, blood flow, and homeostasis. The vascular endothelium also regulates inflammation and immune cell trafficking, and ECs serve as a replicative niche for many bacterial, viral, and protozoan infectious diseases. Endothelial dysfunction can lead to vasodilation and pro-inflammation, which are the hallmarks of many severe diseases. Exosomes are nanoscale membrane-bound vesicles that emerge from cells and serve as important extracellular components, which facilitate communication between cells and maintain homeostasis during normal and pathophysiological states. Exosomes are also involved in gene transfer, inflammation and antigen presentation, and mediation of the immune response during pathogenic states. Protozoa are a diverse group of unicellular organisms that cause many infectious diseases in humans. In this regard, it is becoming increasingly evident that many protozoan parasites (such as Plasmodium, Trypanosoma, Leishmania, and Toxoplasma) utilize exosomes for the transfer of their virulence factors and effector molecules into the host cells, which manipulate the host gene expression, immune responses, and other biological activities to establish and modulate infection. In this review, we discuss the role of the vascular endothelium and exosomes in and their contribution to pathogenesis in malaria, African sleeping sickness, Chagas disease, and leishmaniasis and toxoplasmosis with an emphasis on their actions on the innate and adaptive immune mechanisms of resistance.

Challenges in Chagas Disease Drug Development

The protozoan parasite Trypanosoma cruzi causes Chagas disease, an important public health problem throughout Latin America. Current therapeutic options are characterised by limited efficacy, long treatment regimens and frequent toxic side-effects. Advances in this area have been compromised by gaps in our knowledge of disease pathogenesis, parasite biology and drug activity. Nevertheless, several factors have come together to create a more optimistic scenario. Drug-based research has become more systematic, with increased collaborations between the academic and commercial sectors, often within the framework of not-for-profit consortia. High-throughput screening of compound libraries is being widely applied, and new technical advances are helping to streamline the drug development pipeline. In addition, drug repurposing and optimisation of current treatment regimens, informed by laboratory research, are providing a basis for new clinical trials. Here, we will provide an overview of the current status of Chagas disease drug development, highlight those areas where progress can be expected, and describe how fundamental research is helping to underpin the process.

Efficacy of the Benznidazole+Posaconazole combination therapy in parasitemia reduction: An experimental murine model of acute Chagas

INTRODUCTION:

Benznidazole (BZL) and Nifurtimox (NFX) are the pharmacological treatment for acute phase Chagas Disease (CD); however, therapy resistance and residual mortality development remain important unresolved issues. Posaconazole (POS) has shown a trypanocidal effect in vivo and in vitro. Thus, this study aimed at comparing the T. Cruzi parasitic load-reducing effect of the combination of BZL+POS against that of monotherapy with either, during acute phase CD, in an experimental murine model.

METHODS

Nineteen Wistar rats were randomly allocated to four groups and inoculated with the trypomastigotes of T. cruzi strain´s JChVcl1. The rats were administered anti-parasites from day 20-29 post-infection. The Pizzi and Brener method was used for parasitemia measurement. Longitudinal data analysis for the continuous outcome of repeated measures was performed using parasitemia as the outcome measured at days 20, 22, 24, 27, and 29 post-infection.

RESULTS

All four groups had similar parasitic loads (p=0.143) prior to therapy initiation. Among the three treatment groups, the BZL+POS (n=5) group showed the highest mean parasitic load reduction (p=0.000) compared with the control group. Likewise, the BZL+POS group rats showed an earlier therapeutic effect and were the only ones without parasites in their myocardial samples.

CONCLUSIONS:

Treatment of acute phase CD with BZL+POS was more efficacious at parasitemia and myocardial injury reduction, compared with monotherapy with either.

Notch receptor expression in Trypanosoma cruzi-infected human umbilical vein endothelial cells treated with benznidazole or simvastatin revealed by microarray analysis

Chagas disease is a vector-borne disease caused by the protozoan parasite Trypanosoma cruzi. Current therapy involves benznidazole. Benznidazole and other drugs can modify gene expression patterns, improving the response to the inflammatory influx induced by T. cruzi and decreasing the endothelial activation or immune cell recruitment, among other effects. Here, we performed a microarray analysis of human umbilical vein endothelial cells (HUVECs) treated with benznidazole and the anti-inflammatory drugs acetylsalicylic acid or simvastatin and infected with T. cruzi. Parasitic infection produces differential expression of a set of genes in HUVECs treated with benznidazole alone or a combination with simvastatin or acetylsalicylic acid. The differentially expressed genes were involved in inflammation, adhesion, cardiac function, and remodeling. Notch1 and high mobility group B1 were genes of interest in this analysis due to their importance in placental development, cardiac development, and inflammation. Quantitative polymerase chain reaction confirmation of these two genes indicated that both are upregulated in the presence of benznidazole.

Infectious myocarditis: the role of the cardiac vasculature

Infectious myocarditis is the result of an immune response to a microbial infection of the heart. The blood vessels of the heart, both the intramyocardial microvasculature and the large epicardial coronary arteries, play an important role in the pathogenesis of infectious myocarditis. First of all, in addition to cardiomyocytes, endothelial cells of the cardiac (micro)vasculature are direct targets for infection. Moreover, through the expression of adhesion molecules and antigen presenting Major Histocompatibility Complex molecules, the blood vessels assist in shaping the cellular immune response in infectious myocarditis. In addition, damage and dysfunction of the cardiac (micro)vasculature are associated with thrombus formation as well as aberrant regulation of vascular tone including coronary vasospasm. These in turn can cause cardiac perfusion abnormalities and even myocardial infarction. In this review, we will discuss the role of the cardiac (micro)vasculature in the pathogenesis of infectious myocarditis.

Assessing the Effectiveness of Curative Benznidazole Treatment in Preventing Chronic Cardiac Pathology in Experimental Models of Chagas Disease

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

Biological factors that impinge on Chagas disease drug development

Chagas disease is caused by infection with the insect-transmitted protozoan Trypanosoma cruzi, and is the most important parasitic infection in Latin America. The current drugs, benznidazole and nifurtimox, are characterized by limited efficacy and toxic side-effects, and treatment failures are frequently observed. The urgent need for new therapeutic approaches is being met by a combined effort from the academic and commercial sectors, together with major input from not-for-profit drug development consortia. With the disappointing outcomes of recent clinical trials against chronic Chagas disease, it has become clear that an incomplete understanding of parasite biology and disease pathogenesis is impacting negatively on the development of more effective drugs. In addition, technical issues, including difficulties in establishing parasitological cure in both human patients and animal models, have greatly complicated the assessment of drug efficacy. Here, we outline the major questions that need to be addressed and discuss technical innovations that can be exploited to accelerate the drug development pipeline.

Pharmacokinetics and Tissue Distribution of Benznidazole after Oral Administration in Mice

Specific chemotherapy using benznidazole (BNZ) for Chagas disease during the chronic stage is controversial due to its limited efficacy and toxic effects. Although BNZ has been used to treat Chagas disease since the 1970s, few studies about the biodistribution of this drug exist. In this study, BNZ tissue biodistribution in a murine model and its pharmacokinetic profile in plasma were monitored. A bioanalytical high-performance liquid chromatography method with a UV detector (HPLC-UV) was developed and validated according to the European Medicines Agency for quantification of BNZ in organs and plasma samples prepared by liquid-liquid extraction using ethyl acetate. The developed method was linear in the BNZ concentration, which ranged from 0.1 to 100.0 μg/ml for plasma, spleen, brain, colon, heart, lung, and kidney and from 0.2 to 100.0 μg/ml for liver. Validation assays demonstrated good stability for BNZ under all conditions evaluated. Pharmacokinetic parameters confirmed rapid, but low, absorption of BNZ after oral administration. Biodistribution assays demonstrated different maximum concentrations in organs and similar times to maximum concentration and mean residence times, with means of 40 min and 2.5 h, respectively. Therefore, the biodistribution of BNZ is extensive, reaching organs such as the heart and colon, which are the most relevant organs affected by Trypanosoma cruzi infection, and also the spleen, brain, liver, lungs, and kidneys. Simultaneous analyses of tissues and plasma indicated high BNZ metabolism in the liver. Our results suggest that low bioavailability, instead of inadequate biodistribution, could be responsible for therapeutic failure during the chronic phase of Chagas disease.

Simvastatin Attenuates Endothelial Activation through 15-Epi-Lipoxin A4 Production in Murine Chronic Chagas Cardiomyopathy

Current treatments for chronic Chagas cardiomyopathy, a disease with high mortality rates and caused by the protozoan Trypanosoma cruzi, are unsatisfactory. Myocardial inflammation, including endothelial activation, is responsible for the structural and functional damage seen in the chronic phase. The clinical efficacy of benznidazole could be improved by decreasing chronic inflammation. Statins, which have anti-inflammatory properties, may improve the action of benznidazole. Here, the action of simvastatin in a murine model of chronic Chagas cardiomyopathy and the link with the production of the proresolving eicosanoid 15-epi-lipoxin A4, produced by 5-lipoxygenase, are evaluated. Simvastatin decreased the expression of the adhesion molecules E-selectin, intracellular adhesion molecule type 1 (ICAM-1), and vascular cell adhesion molecule type 1 (VCAM-1) in T. cruzi-infected mice. However, when this drug was administered to 5-lipoxygenase-deficient mice, the anti-inflammatory effect was not observed unless exogenous 15-epi-lipoxin A4 was administered. Thus, in chronic Chagas disease, 5-epi-lipoxin A4 induced by simvastatin treatment could improve the pathophysiological condition of patients by increasing the trypanocidal action of benznidazole.

Nitroheterocyclic drugs cure experimental Trypanosoma cruzi infections more effectively in the chronic stage than in the acute stage

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

Low-dose benznidazole treatment results in parasite clearance and attenuates heart inflammatory reaction in an experimental model of infection with a highly virulent Trypanosoma cruzi strain

Chagas disease, caused by Trypanosoma cruzi, is the main cause of dilated cardiomyopathy in the Americas. Antiparasitic treatment mostly relies on benznidazole (Bzl) due to Nifurtimox shortage or unavailability. Both induce adverse drug effects (ADE) of varied severity in many patients, leading to treatment discontinuation or abandonment. Since dosage may influence ADE, we aimed to assess Bzl efficacy in terms of parasiticidal and anti-inflammatory activity, using doses lower than those previously reported. BALB/c mice infected with the T. cruzi RA strain were treated with different doses of Bzl. Parasitaemia, mortality and weight change were assessed. Parasite load, tissue infiltrates and inflammatory mediators were studied in the heart. Serum creatine kinase (CK) activity was determined as a marker of heart damage. The infection-independent anti-inflammatory properties of Bzl were studied in an in vitro model of LPS-treated cardiomyocyte culture. Treatment with 25 mg/kg/day Bzl turned negative the parasitological parameters, induced a significant decrease in IL-1β, IL-6 and NOS2 in the heart and CK activity in serum, to normal levels. No mortality was observed in infected treated mice. Primary cultured cardiomyocytes treated with Bzl showed that inflammatory mediators were reduced via inhibition of the NF-κB pathway. A Bzl dose lower than that previously reported for treatment of experimental Chagas disease exerts adequate antiparasitic and anti-inflammatory effects leading to parasite clearance and tissue healing. This may be relevant to reassess the dose currently used for the treatment of human Chagas disease, aiming to minimize ADE.

Acute Chagas outbreaks: molecular and biological features of Trypanosoma cruzi isolates, and clinical aspects of acute cases in Santander, Colombia

BACKGROUND

Outbreaks of acute Chagas disease associated with oral transmission are easily detected nowadays with trained health personnel in areas of low endemicity, or in which the vector transmission has been interrupted. Given the biological and genetic diversity of Trypanosoma cruzi, the high morbidity, mortality, and the observed therapeutic failure, new characteristics of these outbreaks need to be addressed at different levels, both in Trypanosoma cruzi as in patient response. The aim of this work was to evaluate the patient's features involved in six outbreaks of acute Chagas disease which occurred in Santander, Colombia, and the characteristics of Trypanosoma cruzi clones isolated from these patients, to establish the potential relationship between the etiologic agent features with host behavior.

METHODS

The clinical, pathological and epidemiological aspects of outbreaks were analyzed. In addition, Trypanosoma cruzi clones were biologically characterized both in vitro and in vivo, and the susceptibility to the classical trypanocidal drugs nifurtimox and benznidazole was evaluated. Trypanosoma cruzi clones were genotyped by means of mini-exon intergenic spacer and cytochrome b genes sequencing.

RESULTS

All clones were DTU I, and based on the mini-exon intergenic spacer, belong to two genotypes: G2 related with sub-urban, and G11 with rural outbreaks. Girón outbreak clones with higher susceptibility to drugs presented G2 genotype and C/T transition in Cyt b. The outbreaks affected mainly young population (±25.9 years), and the mortality rate was 10 %. The cardiac tissue showed intense inflammatory infiltrate, myocardial necrosis and abundant amastigote nests. However, although the gastrointestinal tissue was congestive, no inflammation or parasites were observed.

CONCLUSIONS

Although all clones belong to DTU I, two intra-DTU genotypes were found with the sequencing of the mini-exon intergenic spacer, however there is no strict correlation between genetic groups, the cycles of the parasite or the clinical forms of the disease. Trypanosoma cruzi clones from Girón with higher sensitivity to nifurtimox presented a particular G2 genotype and C/T transition in Cyt b. When the diagnosis was early, the patients responded well to antichagasic treatment, which highlights the importance of diagnosis and treatment early to prevent fatal outcomes associated with these acute episodes.

Novel Gallate Triphenylphosphonium Derivatives with Potent Antichagasic Activity

Chagas disease is one of the most neglected tropical diseases in the world, affecting nearly 15 million people, primarily in Latin America. Only two drugs are used for the treatment of this disease, nifurtimox and benznidazole. These drugs have limited efficacy and frequently induce adverse effects, limiting their usefulness. Consequently, new drugs must be found. In this study, we demonstrated the in vitro trypanocidal effects of a series of four gallic acid derivatives characterized by a gallate group linked to a triphenylphosphonium (TPP⁺) moiety (a delocalized cation) via a hydrocarbon chain of 8, 10, 11, or 12 atoms (TPP⁺-C₈, TPP⁺-C₁₀, TPP⁺-C₁₁, and TPP⁺-C₁₂, respectively). We analyzed parasite viability in isolated parasites (by MTT reduction and flow cytometry) and infected mammalian cells using T. cruzi Y strain trypomastigotes. Among the four derivatives, TPP⁺-C₁₀ and TPP⁺-C₁₂ were the most potent in both models, with EC₅₀ values (in isolated parasites) of 1.0 ± 0.6 and 1.0 ± 0.7 μM, respectively, and were significantly more potent than nifurtimox (EC₅₀ = 4.1 ± 0.6 μM). At 1 μM, TPP⁺-C₁₀ and TPP⁺-C₁₂ induced markers of cell death, such as phosphatidylserine exposure and propidium iodide permeabilization. In addition, at 1 μM, TPP⁺-C₁₀ and TPP⁺-C₁₂ significantly decreased the number of intracellular amastigotes (TPP⁺-C₁₀: 24.3%, TPP⁺-C₁₂: 19.0% of control measurements, as measured by DAPI staining) and the parasite’s DNA load (C₁₀: 10%, C₁₂: 13% of control measurements, as measured by qPCR). Based on the previous mode of action described for these compounds in cancer cells, we explored their mitochondrial effects in isolated trypomastigotes. TPP⁺-C₁₀ and TPP⁺-C₁₂ were the most potent compounds, significantly altering mitochondrial membrane potential at 1 μM (measured by JC-1 fluorescence) and inducing mitochondrial transition pore opening at 5 μM. Taken together, these results indicate that the TPP⁺-C₁₀ and TPP⁺-C₁₂ derivatives of gallic acid are promising trypanocidal agents with mitochondrial activity.

Modulation of oxidative and inflammatory cardiac response by nonselective 1- and 2-cyclooxygenase inhibitor and benznidazole in mice

OBJECTIVES

This study investigated the combined effects of benznidazole (BZ) and ibuprofen (IB) on the oxidative and inflammatory status of the cardiac tissue in vivo.

METHODS

Swiss mice were randomized in groups receiving BZ (100 mg/kg) and IB (400 mg/kg) alone or combined (BZ + IB 200 or 400 mg/kg). Control animals were concurrently treated with 1% carboxymethyl cellulose. All treatments were administered orally for 7 days.

KEY FINDINGS

BZ treatment increased cardiac production of nitrogen/oxygen-reactive species, malondialdeyde, carbonyl proteins, prostaglandins as well as the activities of catalase, superoxide dismutase and glutathione peroxidase. These parameters were attenuated by IB, with the best results at higher dose. Individually, BZ and IB significantly reduced the tissue levels of chemokine ligand 2, tumour necrosis factor-α and IL-10, but no reduction was observed when the treatments were combined.

CONCLUSIONS

BZ triggers an oxidative and nitrosative route, which is associated with increased prostaglandin synthesis and marked damages to the lipids and proteins of the cardiac tissue. IB treatment attenuated reactive stresses triggered by BZ, which was an independent effects of this drug on the endogenous antioxidant enzymes. Individually, but not together, BZ and IB reduced the cardiac inflammatory status, indicating a beneficial and complex drug interaction.

Simvastatin and Benznidazole-Mediated Prevention of Trypanosoma cruzi-Induced Endothelial Activation: Role of 15-epi-lipoxin A4 in the Action of Simvastatin

Trypanosoma cruzi is the causal agent of Chagas Disease that is endemic in Latin American, afflicting more than ten million people approximately. This disease has two phases, acute and chronic. The acute phase is often asymptomatic, but with time it progresses to the chronic phase, affecting the heart and gastrointestinal tract and can be lethal. Chronic Chagas cardiomyopathy involves an inflammatory vasculopathy. Endothelial activation during Chagas disease entails the expression of cell adhesion molecules such as E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) through a mechanism involving NF-κB activation. Currently, specific trypanocidal therapy remains on benznidazole, although new triazole derivatives are promising. A novel strategy is proposed that aims at some pathophysiological processes to facilitate current antiparasitic therapy, decreasing treatment length or doses and slowing disease progress. Simvastatin has anti-inflammatory actions, including improvement of endothelial function, by inducing a novel pro-resolving lipid, the 5-lypoxygenase derivative 15-epi-lipoxin A4 (15-epi-LXA4), which belongs to aspirin-triggered lipoxins. Herein, we propose modifying endothelial activation with simvastatin or benznidazole and evaluate the pathways involved, including induction of 15-epi-LXA4. The effect of 5 μM simvastatin or 20 μM benznidazole upon endothelial activation was assessed in EA.hy926 or HUVEC cells, by E-selectin, ICAM-1 and VCAM-1 expression. 15-epi-LXA4 production and the relationship of both drugs with the NFκB pathway, as measured by IKK-IKB phosphorylation and nuclear migration of p65 protein was also assayed. Both drugs were administered to cell cultures 16 hours before the infection with T. cruzi parasites. Indeed, 5 μM simvastatin as well as 20 μM benznidazole prevented the increase in E-selectin, ICAM-1 and VCAM-1 expression in T. cruzi-infected endothelial cells by decreasing the NF-κB pathway. In conclusion, Simvastatin and benznidazole prevent endothelial activation induced by T. cruzi infection, and the effect of simvastatin is mediated by the inhibition of the NFκB pathway by inducing 15-epi-LXA4 production.

A new experimental model for assessing drug efficacy against Trypanosoma cruzi infection based on highly sensitive in vivo imaging

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

Maia PI, Sesti-Costa R, Lopes CD, Pereira TA, Milanezi CM, da Silva MAP, Lopez RFV, Silva JS, Deflon VM. In vitro and in vivo trypanocidal activity of H2bdtc-loaded solid lipid nanoparticles

The parasite Trypanosoma cruzi causes Chagas disease, which remains a serious public health concern and continues to victimize thousands of people, primarily in the poorest regions of Latin America. In the search for new therapeutic drugs against T. cruzi, here we have evaluated both the in vitro and the in vivo activity of 5-hydroxy-3-methyl-5-phenyl-pyrazoline-1-(S-benzyl dithiocarbazate) (H2bdtc) as a free compound or encapsulated into solid lipid nanoparticles (SLN); we compared the results with those achieved by using the currently employed drug, benznidazole. H2bdtc encapsulated into solid lipid nanoparticles (a) effectively reduced parasitemia in mice at concentrations 100 times lower than that normally employed for benznidazole (clinically applied at a concentration of 400 µmol kg(-1) day(-1)); (b) diminished inflammation and lesions of the liver and heart; and (c) resulted in 100% survival of mice infected with T. cruzi. Therefore, H2bdtc is a potent trypanocidal agent.

Toxic and therapeutic effects of Nifurtimox and Benznidazol on Trypanosoma cruzi ex vivo infection of human placental chorionic villi explants

Nifurtimox (Nfx) and Benznidazole (Bnz) are the only available drugs in use for the treatment of Chagas disease. These drugs are recommended but not fully validated in evidence-based medicine and reports about the differential toxicity of both drugs are controversial. Here, we evaluated the toxic and therapeutic effects of Nfx and Bnz on human placental chorionic villi explants (HPCVE) during ex vivo infection of Trypanosoma cruzi, performing histopathological, histochemical, immunohistochemical as well as immunofluorescence analysis of the tissue. Additionally, we determined the effect of both drugs on parasite load by real time PCR. Bnz prevents the parasite induced tissue damage in ex vivo infected HPCVE compared to Nfx, which is toxic per se. The presence of T. cruzi antigens and DNA in infected explants suggests that these drugs do not impair parasite invasion into the HPCVE. Additionally, our results confirm reports suggesting that Bnz is less toxic than Nfx and support the need for the development of more effective and better-tolerated drugs.