Oxidative stress in chronic cardiopathy associated with Chagas disease

An Update on Vaccines Against Trypanosoma cruzi and Chagas Disease

Chagas disease (CD) is a global health concern, with no existing therapies to prophylactically treat adults traveling to endemic countries or those who may already be infected with Trypanosoma cruzi. The economic burden of Chagas cardiomyopathy and heart failure, due to healthcare costs and lost productivity from premature deaths, provides a strong rationale for investment in the development of immune therapies against CD. Vaccine efficacy is proposed to depend heavily on the induction of a robust Th1 response for the clearance of intracellular pathogens like T. cruzi. In this review, updated information on the efforts for vaccine development against CD is provided.

Immunopathological Mechanisms Underlying Cardiac Damage in Chagas Disease

In Chagas disease, the mechanisms involved in cardiac damage are an active field of study. The factors underlying the evolution of lesions following infection by Trypanosoma cruzi and, in some cases, the persistence of its antigens and the host response, with the ensuing development of clinically observable cardiac damage, are analyzed in this review.

Platelets, Macrophages, and Thromboinflammation in Chagas Disease

Chagas disease (CD) is a major health problem in the Americas and an emerging health problem in Europe and other nonendemic countries. Several studies have documented persistence of the protozoan parasite Trypanosoma cruzi, and oxidative and inflammatory stress are major pathogenic factor. Mural and cardiac thrombi, cardiac arrhythmias, and cardiomyopathy are major clinical features of CD. During T. cruzi infection, parasite-released factors induce endothelial dysfunction along with platelet (PLT) and immune-cell activation. PLTs have a fundamental role in maintaining hemostasis and preventing bleeding after vascular injury. Excessive activation of PLTs and coagulation cascade can result in thrombosis and thromboembolic events, which are recognized to occur in seropositive individuals in early stages of CD when clinically symptomatic heart disease is not apparent. Several host and parasite factors have been identified to signal hypercoagulability and increase the risk of ischemic stroke in early phases of CD. Further, PLT interaction with immune cells and their role in host defense against pathogens and inflammatory processes have only recently been recognized and evolving. In the context of parasitic diseases, PLTs function in directly responding to T. cruzi infection, and PLT interactions with immune cells in shaping the proinflammatory or immunoregulatory function of monocytes, macrophages, and neutrophils remains elusive. How T. cruzi infection alters systemic microenvironment conditions to influence PLT and immune-cell interactions is not understood. In this review, we discuss the current literature, and extrapolate the mechanistic situations to explain how PLT and innate immune cell (especially monocytes and macrophages) interactions might be sustaining hypercoagulability and thromboinflammation in chronic CD.

The repositioned drugs disulfiram/diethyldithiocarbamate combined to benznidazole: Searching for Chagas disease selective therapy, preventing toxicity and drug resistance

Chagas disease (CD) affects at least 6 million people in 21 South American countries besides several thousand in other nations all over the world. It is estimated that at least 14,000 people die every year of CD. Since vaccines are not available, chemotherapy remains of pivotal relevance. About 30% of the treated patients cannot complete the therapy because of severe adverse reactions. Thus, the search for novel drugs is required. Here we tested the benznidazole (BZ) combination with the repositioned drug disulfiram (DSF) and its derivative diethyldithiocarbamate (DETC) upon Trypanosoma cruzi in vitro and in vivo. DETC-BZ combination was synergistic diminishing epimastigote proliferation and enhancing selective indexes up to over 10-fold. DETC was effective upon amastigotes of the BZ- partially resistant Y and the BZ-resistant Colombiana strains. The combination reduced proliferation even using low concentrations (e.g., 2.5 µM). Scanning electron microscopy revealed membrane discontinuities and cell body volume reduction. Transmission electron microscopy revealed remarkable enlargement of endoplasmic reticulum cisternae besides, dilated mitochondria with decreased electron density and disorganized kinetoplast DNA. At advanced stages, the cytoplasm vacuolation apparently impaired compartmentation. The fluorescent probe H2-DCFDA indicates the increased production of reactive oxygen species associated with enhanced lipid peroxidation in parasites incubated with DETC. The biochemical measurement indicates the downmodulation of thiol expression. DETC inhibited superoxide dismutase activity on parasites was more pronounced than in infected mice. In order to approach the DETC effects on intracellular infection, peritoneal macrophages were infected with Colombiana trypomastigotes. DETC addition diminished parasite numbers and the DETC-BZ combination was effective, despite the low concentrations used. In the murine infection, the combination significantly enhanced animal survival, decreasing parasitemia over BZ. Histopathology revealed that low doses of BZ-treated animals presented myocardial amastigote, not observed in combination-treated animals. The picrosirius collagen staining showed reduced myocardial fibrosis. Aminotransferase de aspartate, Aminotransferase de alanine, Creatine kinase, and urea plasma levels demonstrated that the combination was non-toxic. As DSF and DETC can reduce the toxicity of other drugs and resistance phenotypes, such a combination may be safe and effective.

Extraction, Biochemical Characterization, and Health Effects of Native and Degraded Fucoidans from Sargassum crispifolium

In the current investigation, a native crude fucoidan (Ex) was extracted from Sargassum crispifolium, pretreated by single-screw extrusion, and two degraded fucoidans, i.e., ExAh (degradation of Ex by ascorbic acid) and ExHp (degradation of Ex by hydrogen peroxide), were obtained. The extrusion pretreatment increased the extraction yield of fucoidan by approximately 1.73-fold as compared to the non-extruded sample. Among Ex, ExAh, and ExHp, their molecular weight and chemical compositions varied, but the structural features were similar. ExHp possessed the greatest antioxidant activities among the extracted fucoidans. According to the outcome, ExAh exhibited the maximum immune promoting effects via enhanced NO, TNF-α, IL-1β, IL-6, and IL-10 secretion. Thus, both ExHp and ExAh may potentially be used as an effective antioxidant and as immunostimulant agents, which could be of great value in the development of food and nutraceutical products.

Assessment of Radioactive Materials in Albite Granites from Abu Rusheid and Um Naggat, Central Eastern Desert, Egypt

The present study aims to assess Abu Rusheid and Um Naggat albite granite’s natural radioactivity in the Central Eastern Desert, Egypt, using an HPGe laboratory spectrometer. A total of 17 albite granite samples were detected for this study. The activity concentrations were estimated for 238U (range from 204 to 1127 Bq/kg), 226Ra (range from 215 to 1300 Bq/kg), 232Th (from 130 to 1424 Bq/kg) and 40K (from 1108 to 2167 Bq/kg) for Abu Rusheid area. Furthermore 238U (range from 80 to 800 Bq/kg), 226Ra (range from 118 to 1017 Bq/kg), 232Th (from 58 to 674 Bq/kg) and 40K (from 567 to 2329 Bq/kg) for the Um Naggat area. The absorbed dose rates in the outdoor air were measured with average values of 740 nGy/h for Abu Rusheid albite granite and 429 nGy/h for Um Naggat albite granite. The activity concentration and gamma-ray exposure dose rates of the radioactive elements 238U, 226Ra, 232Th and 40K at Abu Rusheid and Um Naggat exceeded the worldwide average values that recommend the necessity of radiation protection regulation. Moreover, the corresponding outdoor annual effective dose (AEDout) was calculated to be 0.9 and 0.5 mSv y−1 for Abu Rusheid and Um Naggat albite granite, respectively, which are lower than the permissible level (1 mSv y−1). By contrast, the indoor annual effective dose (AEDin) exceeded the recommended limit (3.6 and 2.1 for Abu Rusheid and Um Naggat, respectively). Therefore, the two areas are slightly saving for development projects concerning the use of the studied rocks. The statistical analysis displays that the effects of the radiological hazard are associated with the uranium and thorium activity concentrations in Abu Rusheid and Um Naggat albite granites.

Oxidative stress implications for therapeutic vaccine development against Chagas disease

INTRODUCTION

Pathogenesis of Chagas disease (CD) caused by the protozoan parasite Trypanosoma cruzi (T. cruzi) involves chronic oxidative and inflammatory stress. In this review, we discuss the research efforts in therapeutic vaccine development to date and the potential challenges imposed by oxidative stress in achieving an efficient therapeutic vaccine against CD.

AREAS COVERED

This review covers the immune and nonimmune mechanisms of reactive oxygen species production and immune response patterns during T. cruzi infection in CD. A discussion on immunotherapy development efforts, the efficacy of antigen-based immune therapies against T. cruzi, and the role of antioxidants as adjuvants is discussed to provide promising insights to developing future treatment strategies against CD.

EXPERT OPINION

Administration of therapeutic vaccines can be a good option to confront persistent parasitemia in CD by achieving a rapid, short-lived stimulation of type 1 cell-mediated immunity. At the same time, adjunct therapies could play a critical role in the preservation of mitochondrial metabolism and cardiac muscle contractility in CD. We propose combined therapy with antigen-based vaccine and small molecules to control the pathological oxidative insult would be effective in the conservation of cardiac structure and function in CD.

The Use of Antioxidants as Potential Co-Adjuvants to Treat Chronic Chagas Disease

Chagas disease is a neglected tropical disease caused by the flagellated protozoa Trypanosome cruzi. This illness affects to almost 8–12 million people worldwide, however, is endemic to Latin American countries. It is mainly vectorially transmitted by insects of the Triatominae family, although other transmission routes also exist. T. cruzi-infected cardiomyocytes at the chronic stage of the disease display severe mitochondrial dysfunction and high ROS production, leading to chronic myocardial inflammation and heart failure. Under cellular stress, cells usually can launch mitochondrial biogenesis in order to restore energy loss. Key players to begin mitochondrial biogenesis are the PGC-1 (PPARγ coactivator 1) family of transcriptional coactivators, which are activated in response to several stimuli, either by deacetylation or dephosphorylation, and in turn can serve as coactivators for the NRF (nuclear respiratory factor) family of transcription factors. The NRF family of transcriptional activators, namely NRF1 and NRF2, can activate gene expression of oxidative phosphorylation (OXPHOS) components, mitochondrial transcriptional factor (Tfam) and nuclear encoded mitochondrial proteins, leading to mitochondrial biogenesis. On the other hand, NRF2 can activate gene expression of antioxidant enzymes in response to antioxidants, oxidants, electrophile compounds, pharmaceutical and dietary compounds in a mechanism dependent on KEAP1 (Kelch-like ECH-associated protein 1). Since a definitive cure to treat Chagas disease has not been found yet; the use of antioxidants a co-adjuvant therapy has been proposed in an effort to improve mitochondrial functions, biogenesis, and the antioxidant defenses response. Those antioxidants could activate different pathways to begin mitochondrial biogenesis and/or cytoprotective antioxidant defenses. In this review we discuss the main mechanisms of mitochondrial biogenesis and the NRF2-KEAP1 activation pathway. We also reviewed the antioxidants used as co-adjuvant therapy to treat experimental Chagas disease and their action mechanisms and finish with the discussion of antioxidant therapy used in Chagas disease patients.

Alterations to the Cardiac Metabolome Induced by Chronic T. cruzi Infection Relate to the Degree of Cardiac Pathology

Chronic Chagasic cardiomyopathy (CCC) is a Neglected Tropical Disease caused by the parasite Trypanosoma cruzi. The pathognomonic findings in symptomatic CCC patients and animal models includes diffuse cardiac fibrosis and inflammation with persistent parasite presence in the heart. This study investigated chemical alterations in different regions of the heart in relation to cardiac pathology indicators to better understand the long-term pathogenesis of this neglected disease. We used data from echocardiography, fibrosis biomarkers, and histopathological analysis to fully evaluate cardiac pathology. Metabolites isolated from the pericardial and endocardial sides of the right ventricular myocardium were analyzed by liquid chromatography tandem mass spectrometry. The endocardial sections contained significantly less cardiac inflammation and fibrosis than the pericardial sections. Cardiac levels of acylcarnitines, phosphocholines, and other metabolites were significantly disrupted in accordance with cardiac fibrosis, inflammation, and serum fibrosis biomarker levels. These findings have potential implications in treatment and monitoring for CCC patients.

Tryp-ing Up Metabolism: Role of Metabolic Adaptations in Kinetoplastid Disease Pathogenesis

Today, more than a billion people-one-sixth of the world's population-are suffering from neglected tropical diseases. Human African trypanosomiasis, Chagas disease, and leishmaniasis are neglected tropical diseases caused by protozoan parasites belonging to the genera Trypanosoma and Leishmania About half a million people living in tropical and subtropical regions of the world are at risk of contracting one of these three infections. Kinetoplastids have complex life cycles with different morphologies and unique physiological requirements at each life cycle stage. This review covers the latest findings on metabolic pathways impacting disease pathogenesis of kinetoplastids within the mammalian host. Nutrient availability is a key factor shaping in vivo parasite metabolism; thus, kinetoplastids display significant metabolic flexibility. Proteomic and transcriptomic profiles show that intracellular trypanosomatids are able to switch to an energy-efficient metabolism within the mammalian host system. Host metabolic changes can also favor parasite persistence, and contribute to symptom development, in a location-specific fashion. Ultimately, targeted and untargeted metabolomics studies have been a valuable approach to elucidate the specific biochemical pathways affected by infection within the host, leading to translational drug development and diagnostic insights.

Potential Role of Antioxidants as Adjunctive Therapy in Chagas Disease

Chagas disease (CD) is one of the most important neglected tropical diseases in the American continent. Host-derived nitroxidative stress in response to Trypanosoma cruzi infection can induce tissue damage contributing to the progression of Chagas disease. Antioxidant supplementation has been suggested as adjuvant therapy to current treatment. In this article, we synthesize and discuss the current evidence regarding the use of antioxidants as adjunctive compounds to fight harmful reactive oxygen species and lower the tissue oxidative damage during progression of chronic Chagas disease. Several antioxidants evaluated in recent studies have shown potential benefits for the control of oxidative stress in the host's tissues. Melatonin, resveratrol, the combination of vitamin C/vitamin E (vitC/vitE) or curcumin/benznidazole, and mitochondria-targeted antioxidants seem to be beneficial in reducing plasma and cardiac levels of lipid peroxidation products. Nevertheless, further research is needed to validate beneficial effects of antioxidant therapies in Chagas disease.

T. cruzi infection among aged rats: Melatonin as a promising therapeutic molecule

Although T. cruzi was identified as the cause of Chagas disease more than 100 years ago, satisfactory treatments still do not exist, especially for chronic disease. Here we review work suggesting that melatonin could have promise as a Chagas therapeutic. Melatonin has remarkably diverse actions. It is an immunomodulator, an anti-inflammatory, an antioxidant, a free radical scavenger, and has antiapoptotic and anti-aging effects. The elderly (aged 60 years or more) as a group are growing faster than any other age group. Here we discuss the major effects and the mechanisms of action of melatonin on aged T. cruzi-infected rats. Melatonin's protective effects may be consequences of its cooperative antioxidant and immunomodulatory actions. Melatonin modulates oxidative damage, inducing an antioxidant response and reversing age-related thymus regression. Its protective actions could be the result of its anti-apoptotic activity, and by its counteracting the excessive production of corticosterone. This review describes our work showing that host age plays an important and variable influence on the progression of systemic T. cruzi infection and supporting the hypothesis that melatonin should be considered as a powerful therapeutic compound with multiple activities that can improve host homeostasis during experimental T. cruzi infection.

Epidemiology and pathogenesis of maternal-fetal transmission of Trypanosoma cruzi and a case for vaccine development against congenital Chagas disease

Trypanos o ma cruzi (T. cruzi or Tc) is the causative agent of Chagas disease (CD). It is common for patients to suffer from non-specific symptoms or be clinically asymptomatic with acute and chronic conditions acquired through various routes of transmission. The expecting women and their fetuses are vulnerable to congenital transmission of Tc. Pregnant women face formidable health challenges because the frontline antiparasitic drugs, benznidazole and nifurtimox, are contraindicated during pregnancy. However, it is worthwhile to highlight that newborns can be cured if they are diagnosed and given treatment in a timely manner. In this review, we discuss the pathogenesis of maternal-fetal transmission of Tc and provide a justification for the investment in the development of vaccines against congenital CD.

Anti-inflammatory and antioxidant therapies for chagasic myocarditis: a systematic review

The aim of this review was to identify anti-inflammatory and antioxidant therapeutic agents and their effects on patients with chagasic myocarditis. A systematic review of the MEDLINE, EMBASE, WEB OF SCIENCE, SCOPUS, LILACS and CENTRAL databases (Cochrane Library) was carried out without language restrictions. The descriptors used were: 'Chagas cardiomyopathy', 'treatment', 'Chagas disease', 'anti-inflammatory agents', 'Trypanosoma cruzi' and 'antioxidants'. A total of 4,138 articles was identified, six of which were selected for data extraction. Of these, four were related to antioxidant therapy with vitamins C and E supplementation, and two using anti-inflammatory therapy. The studies were carried out in Brazil and were published between 2002 and 2017. Antioxidant therapy with vitamin C and E supplementation increases the activity of antioxidant enzymes and reduces the oxidative markers. There is no conclusive data to support the use of vitamin supplementation and anti-inflammatory therapy in the treatment of chagasic cardiomyopathy. However, the studies indicate the possibility of vitamin supplementation as a new approach to the treatment of Chagas disease. Antioxidant therapy was proven to be a viable alternative for attenuating the oxidative damage caused by chronic chagasic cardiopathy, leading to a better prognosis for patients.

Redox Balance Keepers and Possible Cell Functions Managed by Redox Homeostasis in Trypanosoma cruzi

The toxicity of oxygen and nitrogen reactive species appears to be merely the tip of the iceberg in the world of redox homeostasis. Now, oxidative stress can be seen as a two-sided process; at high concentrations, it causes damage to biomolecules, and thus, trypanosomes have evolved a strong antioxidant defense system to cope with these stressors. At low concentrations, oxidants are essential for cell signaling, and in fact, the oxidants/antioxidants balance may be able to trigger different cell fates. In this comprehensive review, we discuss the current knowledge of the oxidant environment experienced by T. cruzi along the different phases of its life cycle, and the molecular tools exploited by this pathogen to deal with oxidative stress, for better or worse. Further, we discuss the possible redox-regulated processes that could be governed by this oxidative context. Most of the current research has addressed the importance of the trypanosomes' antioxidant network based on its detox activity of harmful species; however, new efforts are necessary to highlight other functions of this network and the mechanisms underlying the fine regulation of the defense machinery, as this represents a master key to hinder crucial pathogen functions. Understanding the relevance of this balance keeper program in parasite biology will give us new perspectives to delineate improved treatment strategies.

Selenium and selenoproteins in prostanoid metabolism and immunity

Selenium (Se) is an essential trace element that functions in the form of the 21st amino acid, selenocysteine (Sec) in a defined set of proteins. Se deficiency is associated with pathological conditions in humans and animals, where incorporation of Sec into selenoproteins is reduced along with their expression and catalytic activity. Supplementation of Se-deficient population with Se has shown health benefits suggesting the importance of Se in physiology. An interesting paradigm to explain, in part, the health benefits of Se stems from the observations that selenoprotein-dependent modulation of inflammation and efficient resolution of inflammation relies on mechanisms involving a group of bioactive lipid mediators, prostanoids, which orchestrate a concerted action toward maintenance and restoration of homeostatic immune responses. Such an effect involves the interaction of various immune cells with these lipid mediators where cellular redox gatekeeper functions of selenoproteins further aid in not only dampening inflammation, but also initiating an effective and active resolution process. Here we have summarized the current literature on the multifaceted roles of Se/selenoproteins in the regulation of these bioactive lipid mediators and their immunomodulatory effects.

Immunity and vaccine development efforts against Trypanosoma cruzi

Trypanosoma cruzi (T. cruzi) is the causative agent for Chagas disease (CD). There is a critical lack of methods for prevention of infection or treatment of acute infection and chronic disease. Studies in experimental models have suggested that the protective immunity against T. cruzi infection requires the elicitation of Th1 cytokines, lytic antibodies and the concerted activities of macrophages, T helper cells, and cytotoxic T lymphocytes (CTLs). In this review, we summarize the research efforts in vaccine development to date and the challenges faced in achieving an efficient prophylactic or therapeutic vaccine against human CD.

Biomarkers of Oxidative Stress and Inflammation in Chagasic Myocardiopathy

Introduction:

The fact that only part of the population that lives in endemic areas gets Chagas disease and that only some of the patients with chronic infection develop symptoms, supports the importance of investigating the factors of each host in the susceptibility and the development of the disease. Chronic pathological processes and progressive inflammation lead to alterations in the cellular antioxidant status. This imbalance would contribute to the destruction of the parasite and would be related to the cardiac damage observed in patients with chagasic cardiomyopathy.

Objective:

The objective of the present study was to determine the plasma activity of oxidative stress and inflammatory biomarkers: SOD, CAT, GPx, TBARS and TNF-α in chagasic patients with and without cardiomyopathy and healthy individuals.

Aim:

The aim of the present study is to demonstrate the predisposition to severe forms of chagasic heart disease by quantifying the biomarkers mentioned in blood from the study population.

Results and Conclusion:

The results show significant differences in the enzymatic activities in the different groups of patients, which would mean at the cellular level, an alteration of the antioxidant capacity. Contrary to what we expected (a depletion of these enzymes), patients show an increase in antioxidant activity, that is, they respond to the generation of free radicals. The same trend is observed in the case of TBARS that are elevated in the case of chagasic patients, indicating a high degree of lipid peroxidation and oxidative damage. Regarding TNF-α levels, we found statistically significant differences, which show an active and chronic inflammatory state in these patients. Although we have found significant differences between the CN group and the other groups of patients, we should indicate that between the MCC and ECsinMCC groups, the results obtained did not show marked differences. This is important since it has been shown that patients infected with Tc have a marked antioxidant potential and are able to respond to the oxidative stress induced by the parasite, although this would not be decisive in the evolution of the disease.

Pathology and Pathogenesis of Chagas Heart Disease

Chagas heart disease is an inflammatory cardiomyopathy that develops in approximately one-third of people infected with the protozoan parasite Trypanosoma cruzi. One way T. cruzi is transmitted to people is through contact with infected kissing bugs, which are found in much of the Western Hemisphere, including in vast areas of the United States. The epidemiology of T. cruzi and Chagas heart disease and the varied mechanisms leading to myocyte destruction, mononuclear cell infiltration, fibrosis, and edema in the heart have been extensively studied by hundreds of scientists for more than 100 years. Despite this wealth of knowledge, it is still impossible to predict what will happen in an individual infected with T. cruzi because of the tremendous variability in clonal parasite virulence and human susceptibility to infection and the lack of definitive molecular predictors of outcome from either side of the host-parasite equation. Further, while several distinct mechanisms of pathogenesis have been studied in isolation, it is certain that multiple coincident mechanisms combine to determine the ultimate outcome. For these reasons, Chagas disease is best considered a collection of related but distinct illnesses. This review highlights the pathology and pathogenesis of the most common adverse sequela of T. cruzi infection-Chagas heart disease-and concludes with a discussion of key unanswered questions and a view to the future.

Antioxidant effect of Morus nigra on Chagas disease progression

Considering the widespread popular use of Morus nigra and the amount of scientific information on its antioxidant and anti-inflammatory activity, the effectiveness of this phytotherapeutic compound in the parasitemia progression during the acute phase of Chagas disease and its role in the development of the inflammatory process as well as its effects on the oxidative damage in the chronic phase of infection were evaluated. Thus, 96 male Swiss mice were randomly divided into eight groups, four groups were uninfected controls, and four groups were intraperitoneally infected with 5.0 x 104 blood trypomastigotes forms of T. cruzi QM2 strain. Four batches composed of one uninfected and one infected group were respectively treated with 70% alcohol solution and 25 μL, 50 μL and 75 μL of the phytotherapeutic compound. Levels of antioxidant elements (TBARS, FRAP, GSH and Sulfhydryl groups) were measured in plasma samples. The phytotherapeutic compound's antioxidant activity was measured by polyphenol and total flavonoid quantification, DPPH, NO, and FRAP method. Our results showed that the vehicle influenced some of the results that may have physiological relevance in Chagas disease. However, an important action of M. nigra tincture was observed in the progression of Chagas disease, since our results demonstrated a reduction in parasitemia of treated groups when compared to controls, especially in the group receiving 25 µL. However, in the chronic phase, the 50-µL dosage presented a better activity on some antioxidant defenses and minimized the tissue inflammatory process. Results indicated an important action of M. nigra tincture on the Chagas disease progression.

Changes in Proteome Profile of Peripheral Blood Mononuclear Cells in Chronic Chagas Disease

Trypanosoma cruzi (Tc) infection causes chagasic cardiomyopathy; however, why 30-40% of the patients develop clinical disease is not known. To discover the pathomechanisms in disease progression, we obtained the proteome signature of peripheral blood mononuclear cells (PBMCs) of normal healthy controls (N/H, n = 30) and subjects that were seropositive for Tc-specific antibodies, but were clinically asymptomatic (C/A, n = 25) or clinically symptomatic (C/S, n = 28) with cardiac involvement and left ventricular dysfunction. Protein samples were labeled with BODIPY FL-maleimide (dynamic range: > 4 orders of magnitude, detection limit: 5 f-mol) and resolved by two-dimensional gel electrophoresis (2D-GE). After normalizing the gel images, protein spots that exhibited differential abundance in any of the two groups were analyzed by mass spectrometry, and searched against UniProt human database for protein identification. We found 213 and 199 protein spots (fold change: |≥ 1.5|, p< 0.05) were differentially abundant in C/A and C/S individuals, respectively, with respect to N/H controls. Ingenuity Pathway Analysis (IPA) of PBMCs proteome dataset identified an increase in disorganization of cytoskeletal assembly and recruitment/activation and migration of immune cells in all chagasic subjects, though the invasion capacity of cells was decreased in C/S individuals. IPA predicted with high probability a decline in cell survival and free radical scavenging capacity in C/S (but not C/A) subjects. The MYC/SP1 transcription factors that regulate hypoxia and oxidative/inflammatory stress were predicted to be key targets in the context of control of Chagas disease severity. Further, MARS-modeling identified a panel of proteins that had >93% prediction success in classifying infected individuals with no disease and those with cardiac involvement and LV dysfunction. In conclusion, we have identified molecular pathways and a panel of proteins that could aid in detecting seropositive individuals at risk of developing cardiomyopathy.

Molecular mechanisms of myocarditis caused by Trypanosoma cruzi

PURPOSE OF REVIEW

American trypanosomiasis, or Chagas disease, is a lifelong and persistent infection caused by the protozoan Trypanosoma cruzi and is the most significant cause of morbidity and mortality in South and Central America. Owing to immigration and additional risks from blood transfusion and organ transplantation, the number of reported cases of Chagas disease has increased recently in Europe and the USA. The disease is caused by a moderate to intense lasting inflammatory response that triggers local expression of inflammatory mediators and activates and recruits leukocytes to various tissues to eliminate the parasites.

RECENT FINDINGS

This long-term inflammatory process triggers biochemical, physiological and morphological alterations and clinical changes in the digestive, nervous and cardiac (e.g. myocarditis, arrhythmias, congestive heart failure, autonomic dysfunctions and microcirculatory disturbances) systems. Indeed, the pathogenesis of Chagas disease is intricate and multifactorial, and the roles of the parasite and the immune response in initiating and maintaining the disease are still controversial.

SUMMARY

In this review, we discuss the current knowledge of 'strategies' employed by the parasite to persist in the host and host defence mechanisms against Trypanosoma cruzi infection, which can result in equilibrium (absence of the disease) or disease development, mainly in the cardiac systems.

Interleukin-17, oxidative stress, and inflammation: role of melatonin during Trypanosoma cruzi infection

Although the exact etiology of Chagas' disease remains unknown, the inflammatory process and oxidative stress are believed to be the main contributors to the dysfunction and pathogenesis during chronic Trypanosoma cruzi infection. Our hypothesis is that melatonin administered for 2 months daily could modulate the oxidative stress and the inflammatory response during the chronic infection. Flow cytometric analysis of macrophages and antigen-presenting cells (APC), expression of RT1B as well as LFA-1 and MCP-1 in CD4(+) and CD8(+) T cells and levels of interleukin-17A were assessed. The oxidative stress was evaluated through lipid peroxidation (LPO) analysis on the plasma of thiobarbituric acid-reactive substances (TBARS) and nitric oxide production. Decreased concentrations of nitrite and TBARS were found in infected and melatonin-treated animals, as well as a rising trend in the production of IL-17A as compared to infected and untreated counterparts. A significant decrease was found in the percentages of CD4(+) and CD8(+) T lymphocytes MCP-1 producers for infected and melatonin-treated rats. Reduced percentage of CD8(+) T cells producing LFA-1 was observed in control and melatonin-treated animals as compared to untreated rats. The cellular response of peritoneal APC cells and macrophages significantly dropped in infected and treated animals. As an endpoint, the use of antioxidant compounds such as melatonin emerges as a new and promising approach to control the oxidative stress during the chronic Chagas' disease partially mediated through the abrogation of LPO and the prevention of the inflammatory response and can be used for further investigation on treatment trials for other infectious diseases.

A change of heart: oxidative stress in governing muscle function?

Redox/cysteine modification of proteins that regulate calcium cycling can affect contraction in striated muscles. Understanding the nature of these modifications would present the possibility of enhancing cardiac function through reversible cysteine modification of proteins, with potential therapeutic value in heart failure with diastolic dysfunction. Both heart failure and muscular dystrophy are characterized by abnormal redox balance and nitrosative stress. Recent evidence supports the synergistic role of oxidative stress and inflammation in the progression of heart failure with preserved ejection fraction, in concert with endothelial dysfunction and impaired nitric oxide-cyclic guanosine monophosphate-protein kinase G signalling via modification of the giant protein titin. Although antioxidant therapeutics in heart failure with diastolic dysfunction have no marked beneficial effects on the outcome of patients, it, however, remains critical to the understanding of the complex interactions of oxidative/nitrosative stress with pro-inflammatory mechanisms, metabolic dysfunction, and the redox modification of proteins characteristic of heart failure. These may highlight novel approaches to therapeutic strategies for heart failure with diastolic dysfunction. In this review, we provide an overview of oxidative stress and its effects on pathophysiological pathways. We describe the molecular mechanisms driving oxidative modification of proteins and subsequent effects on contractile function, and, finally, we discuss potential therapeutic opportunities for heart failure with diastolic dysfunction.

Mitochondrial dysfunction in skeletal muscle during experimental Chagas disease

Trypanosoma cruzi invasion and replication in cardiomyocytes and other tissues induce cellular injuries and cytotoxic reactions, with the production of inflammatory cytokines and nitric oxide, both sources of reactive oxygen species. The myocyte response to oxidative stress involves the progression of cellular changes primarily targeting mitochondria. Similar alterations could be taking place in mitochondria from the skeletal muscle; if that is the case, a simple skeletal muscle biopsy would give information about the cardiac energetic production that could be used as a predictor of the chagasic cardiopathy evolution. Therefore, in the present paper we studied skeletal muscle mitochondrial structure and the enzymatic activity of citrate synthase and respiratory chain complexes I to IV (CI-CIV), in Albino Swiss mice infected with T. cruzi, Tulahuen strain and SGO Z12 and Lucky isolates, along the infection. Changes in the mitochondrial structure were detected in 100% of the mitochondria analyzed from the infected groups: they all presented at least 1 significant abnormality such as increase in their matrix or disorganization of their cristae, which are probably related to the enzymatic dysfunction. When we studied the Krebs cycle functionality through the measurement of the specific citrate synthase activity, we found it to be significantly diminished during the acute phase of the infection in Tulahuen and SGO Z12 infected groups with respect to the control one; citrate synthase activity from the Lucky group was significantly increased (p<0.05). The activity of this enzyme was reduced in all the infected groups during the chronic asymptomatic phase (p<0.001) and return to normal values (Tulahuen and SGO Z12) or increased its activity (Lucky) by day 365 post-infection (p.i.). When the mitochondrial respiratory chain was analyzed from the acute to the chronic phase of the infection through the measurement of the activity of complexes I to IV, the activity of CI remained similar to control in Tulahuen and Lucky groups, but was significantly augmented in the SGO Z12 one in the acute and chronic phases (p<0.05). CII increased its activity in Tulahuen and Lucky groups by day 75 p.i. and in SGO Z12 by day 365 p.i. (p<0.05). CIII showed a similar behavior in the 3 infected groups, remaining similar to control values in the first two stages of the infection and significantly increasing later on (p<0.0001). CIV showed an increase in its activity in Lucky throughout all stages of infection (p<0.0001) and an increase in Tulahuen by day 365days p.i. (p<0.0001); SGO Z12 on the other hand, showed a decreased CIV activity at the same time. The structural changes in skeletal muscle mitochondria and their altered enzyme activity began in the acute phase of infection, probably modifying the ability of mitochondria to generate energy; these changes were not compensated in the rest of the phases of the infection. Chagas is a systemic disease, which produces not only heart damage but also permanent skeletal muscle alterations.

Markers of oxidative stress in adipose tissue during Trypanosoma cruzi infection

The protozoan parasite Trypanosoma cruzi causes Chagas disease. Cardiac and adipose tissues are among the early targets of infection and are sites of persistent infection. In the heart and adipose tissue, T. cruzi infection results in an upregulation of pro-inflammatory mediators. In the heart, infection is associated with an increase in the markers of oxidative stress. To date, markers of oxidative stress have not been evaluated in adipose tissue in this infection. Brown and white adipose tissues were obtained from CD-1 mice infected with the Brazil strain of T. cruzi for 15, 30, and 130 days post infection. Protein carbonylation and lipid peroxidation assays were performed on these samples. There was an upregulation of these markers of oxidative stress at all time-points in both white and brown adipose tissue. Determinants of anti-oxidative stress were downregulated at similar time-points. This increase in oxidative stress during T. cruzi infection most likely has a deleterious effect on host metabolism and on the heart.

Synthesis and evaluation of antioxidant and trypanocidal properties of a selected series of coumarin derivatives

This article describes the preparation and characterization of a selected series of coumarin derivatives with the aim of evaluating their antioxidant properties and their activity against Trypanosoma cruzi, the parasite responsible for Chagas disease. All the derivatives demonstrated moderate trypanocidal activity in the epimastigote and trypomastigote stages (clone Dm28c), with Compound 3 presenting the highest trypanocidal activity of the entire series, displaying higher activity than nifurtimox, which was used as a reference compound. In addition to the trypanocidal activity, this compound proved to have a very interesting antioxidant profile, as well as no cytotoxicity. These preliminary findings encouraged the authors to study the future structural optimization of this scaffold.

MnSODtg mice control myocardial inflammatory and oxidative stress and remodeling responses elicited in chronic Chagas disease

Background

We utilized genetically modified mice equipped with a variable capacity to scavenge mitochondrial and cellular reactive oxygen species to investigate the pathological significance of oxidative stress in Chagas disease.

Methods and Results

C57BL/6 mice (wild type, MnSOD^tg, MnSOD^+/−, GPx1^−/−) were infected with Trypanosoma cruzi and harvested during the chronic disease phase. Chronically infected mice exhibited a substantial increase in plasma levels of inflammatory markers (nitric oxide, myeloperoxidase), lactate dehydrogenase, and myocardial levels of inflammatory infiltrate and oxidative adducts (malondialdehyde, carbonyls, 3‐nitrotyrosine) in the order of wild type=MnSOD^+/−>GPx1^−/−>MnSOD^tg. Myocardial mitochondrial damage was pronounced and associated with a >50% decline in mitochondrial DNA content in chronically infected wild‐type and GPx1^−/− mice. Imaging of intact heart for cardiomyocytes and collagen by the nonlinear optical microscopy techniques of multiphoton fluorescence/second harmonic generation showed a significant increase in collagen (>10‐fold) in chronically infected wild‐type mice, whereas GPx1^−/− mice exhibited a basal increase in collagen that did not change during the chronic phase. Chronically infected MnSOD^tg mice exhibited a marginal decline in mitochondrial DNA content and no changes in collagen signal in the myocardium. P47^phox−/− mice lacking phagocyte‐generated reactive oxygen species sustained a low level of myocardial oxidative stress and mitochondrial DNA damage in response to Trypanosoma cruzi infection. Yet chronically infected p47^phox−/− mice exhibited increase in myocardial inflammatory and remodeling responses, similar to that noted in chronically infected wild‐type mice.

Conclusions

Inhibition of oxidative burst of phagocytes was not sufficient to prevent pathological cardiac remodeling in Chagas disease. Instead, enhancing the mitochondrial reactive oxygen species scavenging capacity was beneficial in controlling the inflammatory and oxidative pathology and the cardiac remodeling responses that are hallmarks of chronic Chagas disease.

Carvedilol enhances the antioxidant effect of vitamins E and C in chronic Chagas heart disease

Background

Chagas disease is still an important endemic disease in Brazil, and the cardiac involvement is its more severe manifestation.

Objective

To verify whether the concomitant use of carvedilol will enhance the antioxidant effect of vitamins E and C in reducing the systemic oxidative stress in chronic Chagas heart disease.

Methods

A total of 42 patients with Chagas heart disease were studied. They were divided into four groups according to the modified Los Andes classification: 10 patients in group IA (normal electrocardiogram and echocardiogram; no cardiac involvement); 20 patients in group IB (normal electrocardiogram and abnormal echocardiogram; mild cardiac involvement); eight patients in group II (abnormal electrocardiogram and echocardiogram; no heart failure; moderate cardiac involvement); and four patients in group III (abnormal electrocardiogram and echocardiogram with heart failure; severe cardiac involvement). Blood levels of markers of oxidative stress were determined before and after a six-month period of treatment with carvedilol, and six months after combined therapy of carvedilol with vitamins E and C. The markers analyzed were as follows: activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and reductase, myeloperoxidade and adenosine deaminase; and the levels of reduced glutathione, thiobarbituric-acid reactive substances, protein carbonyls, vitamin E, and nitric oxide.

Results

After treatment with carvedilol, all groups showed significant decrease in protein carbonyls and reduced glutathione levels, whereas nitric oxide levels and adenosine activity increased significantly only in the less severely affected group (IA). In addition, the activity of most of the antioxidant enzymes was decreased in the less severely affected groups (IA and IB). By combining the vitamins with carvedilol, a reduction in protein damage, in glutathione levels, and in the activity of most of the antioxidant enzymes were observed.

Conclusions

The decrease in oxidative stress levels observed by means of the markers tested was more significant when carvedilol was used in combination with the antioxidant vitamins. The findings suggest that both carvedilol alone and in combination with the vitamins were effective in attenuating the systemic oxidative stress in patients with Chagas heart disease, especially those less severely affected, thus suggesting the possibility of synergism between these compounds.

Innate immune responses and antioxidant/oxidant imbalance are major determinants of human Chagas disease

Background

We investigated the pathological and diagnostic role of selected markers of inflammation, oxidant/antioxidant status, and cellular injury in human Chagas disease.

Methods

Seropositive/chagasic subjects characterized as clinically-symptomatic or clinically-asymptomatic (n = 116), seronegative/cardiac subjects (n = 102), and seronegative/healthy subjects (n = 45) were analyzed for peripheral blood biomarkers.

Results

Seropositive/chagasic subjects exhibited an increase in sera or plasma levels of myeloperoxidase (MPO, 2.8-fold), advanced oxidation protein products (AOPP, 56%), nitrite (5.7-fold), lipid peroxides (LPO, 12–17-fold) and malondialdehyde (MDA, 4–6-fold); and a decline in superoxide dismutase (SOD, 52%) and glutathione (GSH, 75%) contents. Correlation analysis identified a significant (p<0.001) linear relationship between inflammatory markers (AOPP/nitrite: r = 0.877), inflammation and antioxidant/oxidant status (AOPP/glutathione peroxidase (GPX): r = 0.902, AOPP/GSH: r = 0.806, Nitrite/GPX: 0.773, Nitrite/LPO: 0.805, MDA/MPO: 0.718), and antioxidant/oxidant levels (GPX/MDA: r = 0.768) in chagasic subjects. Of these, MPO, LPO and nitrite biomarkers were highly specific and sensitive for distinguishing seropositive/chagasic subjects from seronegative/healthy controls (p<0.001, training and fitting AUC/ROC >0.95). The MPO (r = 0.664) and LPO (r = 0.841) levels were also correlated with clinical disease state in chagasic subjects (p<0.001). Seronegative/cardiac subjects exhibited up to 77% decline in SOD, 3–5-fold increase in LPO and glutamate pyruvate transaminase (GPT) levels, and statistically insignificant change in MPO, AOPP, MDA, GPX, GSH, and creatine kinase (CK) levels.

Conclusions

The interlinked effects of innate immune responses and antioxidant/oxidant imbalance are major determinants of human Chagas disease. The MPO, LPO and nitrite are excellent biomarkers for diagnosing seropositive/chagasic subjects, and MPO and LPO levels have potential utility in identifying clinical severity of Chagas disease.

Chagas disease is a chronic disease of the heart, and caused by Trypanosoma cruzi infection. In this study, we have monitored the biomarkers of inflammation caused by innate immune cells, oxidative stress, and antioxidant status in seropositive/chagasic, seronegative/cardiac disease, and seronegative/healthy subjects. Our goal was to evaluate the diagnostic efficacy of selected biomarkers, and determine if any of the biomarkers are good indicators of clinical severity of Chagas disease. We also determined whether sera or plasma serve as a better source, and if sample storage affects the estimation of the selected biomarkers. Our data suggest that innate immune responses and antioxidant/oxidant imbalance are inter-linked pathological events in Chagas disease. We have identified peripheral blood markers (myeloperoxidase, lipid hydroperoxides and nitrite) that strongly distinguish seropositive/chagasic subjects from controls. Further, we found that myeloperoxidase and lipid hydroperoxide levels have potential utility in identifying seropositive subjects at risk of developing clinically symptomatic disease.

Defects of mtDNA replication impaired mitochondrial biogenesis during Trypanosoma cruzi infection in human cardiomyocytes and chagasic patients: the role of Nrf1/2 and antioxidant response

BACKGROUND

Mitochondrial dysfunction is a key determinant in chagasic cardiomyopathy development in mice; however, its relevance in human Chagas disease is not known. We determined if defects in mitochondrial biogenesis and dysregulation of peroxisome proliferator-activated receptor gamma (PPARγ) coactivator-1 (PGC-1)-regulated transcriptional pathways constitute a mechanism or mechanisms underlying mitochondrial oxidative-phosphorylation (OXPHOS) deficiency in human Chagas disease.

METHODS AND RESULTS

We utilized human cardiomyocytes and left-ventricular tissue from chagasic and other cardiomyopathy patients and healthy donors (n>6/group). We noted no change in citrate synthase activity, yet mRNA and/or protein levels of subunits of the respiratory complexes were significantly decreased in Trypanosoma cruzi-infected cardiomyocytes (0 to 24 hours) and chagasic hearts. We observed increased mRNA and decreased nuclear localization of PGC-1-coactivated transcription factors, yet the expression of genes for PPARγ-regulated fatty acid oxidation and nuclear respiratory factor (NRF1/2)-regulated mtDNA replication and transcription machinery was enhanced in infected cardiomyocytes and chagasic hearts. The D-loop formation was normal or higher, but mtDNA replication and mtDNA content were decreased by 83% and 40% to 65%, respectively. Subsequently, we noted that reactive oxygen species (ROS), oxidative stress, and mtDNA oxidation were significantly increased, yet NRF1/2-regulated antioxidant gene expression remained compromised in infected cardiomyocytes and chagasic hearts.

CONCLUSIONS

The replication of mtDNA was severely compromised, resulting in a significant loss of mtDNA and expression of OXPHOS genes in T cruzi-infected cardiomyocytes and chagasic hearts. Our data suggest increased ROS generation and selective functional incapacity of NRF2-mediated antioxidant gene expression played a role in the defects in mtDNA replication and unfitness of mtDNA for replication and gene expression in Chagas disease.

Chronic indeterminate phase of Chagas’ disease: mitochondrial involvement in infection with two strains

Chagasic cardiopathy has become one of the most frequent causes of heart failure and sudden death, as well as one of the most common causes of cardio-embolic stroke in Latin America. The myocyte response to oxidative stress involves the progression of cellular changes, primarily targeting the mitochondria and modifying therefore the energy supply. In this paper we analysed the effect of the infection of mice with 2 different strains of Trypanosoma cruzi (Tulahuen and SGO Z12) in the chronic indeterminate stage (75 days post-infection), upon the structure and function of cardiac mitochondria. The structural results showed that 83% of the mitochondria from the Tulahuen-infected mice presented an increase in their matrix and 91% of the mitochondria from the SGO Z12-infected group showed a reduction in their diameter (P < 0·05). When the Krebs cycle and mitochondrial respiratory chain functionality was analysed through the measurement of the citrate synthase and complexes I to IV activity, it showed that their activity was altered in all cases in a similar manner in both infected groups. In this paper we have demonstrated that the chronic indeterminate phase is not ‘silent’ and that cardiac mitochondria are clearly involved in the genesis and progression to the chronic chagasic cardiopathy when different factors alter the host-parasite equilibrium.

Current understanding of immunity to Trypanosoma cruzi infection and pathogenesis of Chagas disease

Chagas disease caused by Trypanosoma cruzi remains an important neglected tropical disease and a cause of significant morbidity and mortality. No longer confined to endemic areas of Latin America, it is now found in non-endemic areas due to immigration. The parasite may persist in any tissue, but in recent years, there has been increased recognition of adipose tissue both as an early target of infection and a reservoir of chronic infection. The major complications of this disease are cardiomyopathy and megasyndromes involving the gastrointestinal tract. The pathogenesis of Chagas disease is complex and multifactorial involving many interactive pathways. The significance of innate immunity, including the contributions of cytokines, chemokines, reactive oxygen species, and oxidative stress, has been emphasized. The role of the components of the eicosanoid pathway such as thromboxane A(2) and the lipoxins has been demonstrated to have profound effects as both pro- and anti-inflammatory factors. Additionally, we discuss the vasoconstrictive actions of thromboxane A(2) and endothelin-1 in Chagas disease. Human immunity to T. cruzi infection and its role in pathogen control and disease progression have not been fully investigated. However, recently, it was demonstrated that a reduction in the anti-inflammatory cytokine IL-10 was associated with clinically significant chronic chagasic cardiomyopathy.

Antitrypanosomal and antioxidant properties of 4-hydroxycoumarins derivatives

In the present communication we prepared a series of six 4-hydroxycoumarin derivatives, isosters of quercetin, recognized as an antioxidant natural compound, with the aim of evaluating the antitrypanosomal activity against Trypanosoma cruzi, the parasite responsible for Chagas disease, and the antioxidant properties. We have used the 4-hydroxycoumarin moiety (compound 1) as the molecular template for the synthesis of compounds 2-7. These derivates have shown moderate trypanocidal activity. However they have been proved to be good antioxidants. In particular compound 7 is the most active antioxidant and it is, therefore, a potential candidate for a successful employment in conditions characterized by free radicals overproduction.

Chronic Chagas' heart disease: a disease on its way to becoming a worldwide health problem: epidemiology, etiopathology, treatment, pathogenesis and laboratory medicine

Chagas' disease, caused by Trypanosoma cruzi infection, is ranked as the most serious parasitic disease in Latin America. Nearly 30% of infected patients develop life-threatening complications, and with a latency of 10-30 years, mostly Chagas' heart disease which is currently the major cause of morbidity and mortality in Latin America, enormously burdening economic resources and dramatically affecting patients' social and labor situations. Because of increasing migration, international tourism and parasite transfer by blood contact, intrauterine transfer and organ transplantation, Chagas' heart disease could potentially become a worldwide problem. To raise awareness of this problem, we reflect on the epidemiology and etiopathology of Chagas' disease, particularly Chagas' heart disease. To counteract Chagas' heart disease, in addition to the general interruption of the infection cycle and chemotherapeutic elimination of the infection agent, early and effective causal or symptomatic therapies would be indispensable. Prerequisites for this are improved knowledge of the pathogenesis and optimized patient management. From economic and logistics viewpoints, this last prerequisite should be performed using laboratory medicine tools. Consequently, we first summarize the mechanisms that have been suggested as driving Chagas' heart disease, mainly those associated with the presence of autoantibodies against G-protein-coupled receptors; secondly, we indicate new treatment strategies involving autoantibody apheresis and in vivo autoantibody neutralization; thirdly, we present laboratory medicine tools such as autoantibody estimation and heart marker measurement, proposed for diagnosis, risk assessment and patient guidance and lastly, we critically reflect upon the increase in inflammation and oxidative stress markers in Chagas' heart disease.

Cardiac-oxidized antigens are targets of immune recognition by antibodies and potential molecular determinants in chagas disease pathogenesis

Trypanosoma cruzi elicits reactive oxygen species (ROS) of inflammatory and mitochondrial origin in infected hosts. In this study, we examined ROS-induced oxidative modifications in the heart and determined whether the resultant oxidized cardiac proteins are targets of immune response and of pathological significance in Chagas disease. Heart biopsies from chagasic mice, rats and human patients exhibited, when compared to those from normal controls, a substantial increase in protein 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), carbonyl, and 3-nitrotyrosine (3-NT) adducts. To evaluate whether oxidized proteins gain antigenic properties, heart homogenates or isolated cardiomyocytes were oxidized in vitro and one- or two-dimensional gel electrophoresis (2D-GE)/Western blotting (WB) was performed to investigate the proteomic oxidative changes and recognition of oxidized proteins by sera antibodies in chagasic rodents (mice, rats) and human patients. Human cardiomyocytes exhibited LD(50) sensitivity to 30 µM 4-HNE and 100 µM H(2)O(2) at 6 h and 12 h, respectively. In vitro oxidation with 4-HNE or H(2)O(2) resulted in a substantial increase in 4-HNE- and carbonyl-modified proteins that correlated with increased recognition of cardiac (cardiomyocytes) proteins by sera antibodies of chagasic rodents and human patients. 2D-GE/Western blotting followed by MALDI-TOF-MS/MS analysis to identify cardiac proteins that were oxidized and recognized by human chagasic sera yielded 82 unique proteins. We validated the 2D-GE results by enzyme-linked immunosorbent assay (ELISA) and WB and demonstrated that oxidation of recombinant titin enhanced its immunogenicity and recognition by sera antibodies from chagasic hosts (rats and humans). Treatment of infected rats with phenyl-α-tert-butyl nitrone (PBN, antioxidant) resulted in normalized immune detection of cardiac proteins associated with control of cardiac pathology and preservation of heart contractile function in chagasic rats. We conclude that ROS-induced, cardiac-oxidized antigens are targets of immune recognition by antibodies and molecular determinants for pathogenesis during Chagas disease.

Proteome expression and carbonylation changes during Trypanosoma cruzi infection and Chagas disease in rats

Inflammation and oxidative stress, elicited by Trypanosoma cruzi infection, are important pathologic events during progressive Chagasic cardiomyopathy. In this study, we infected Sprague-Dawley rats with T. cruzi, and treated with phenyl-α-tert-butylnitrone (PBN-antioxidant) and/or benznidazole (BZ-anti-parasite). We employed two-dimensional gel electrophoresis/mass spectrometry to investigate (a) the plasma proteomic changes associated with infection and disease development, and (b) the beneficial effects of PBN and BZ in controlling the disease-associated plasma profile. Matrix-assisted laser desorption ionization/time of flight (MALDI-TOF) tandem MS (MS/MS) analysis of differentially expressed (total 146) and oxidized (total 48) protein spots yielded 92 unique proteins. Our data showed that treatment with PBN and BZ restored the differential expression of 65% and 30% of the disease-associated proteins to normal level, respectively, and PBN prevented development of oxidative adducts on plasma proteins. Western blotting to detect dinitrophenyl-derivatized carbonyl-proteins revealed plasma proteins were maximally oxidized during acute infection. Functional and disease/disorder analyses allocated a majority of the differentially expressed and oxidized proteins into inflammation/immunity and lipid metabolism categories and to molecular pathways associated with heart disease (e.g. cardiac infarction, contractile dysfunction, hypertrophy, and hypertension) in chagasic rats, and to curative pathways (e.g. ROS scavenging capacity, immune regulation) in infected rats treated with PBN and/or BZ. We validated the two-dimensional gel electrophoresis results by Western blotting, and demonstrated that the disease-associated increased expression of gelsolin and vimentin and release of cardiac MYL2 in the plasma of chagasic rats was returned to control level by PBN/BZ treatment. Increased plasma levels of gelsolin, MYL2 and vimentin were directly correlated with the severity of cardiac disease in human chagasic patients. Together, these results demonstrate the plasma oxidative and inflammatory response profile, and plasma detection of cardiac proteins parallels the pathologic events contributing to Chagas disease development, and is of potential utility in diagnosing disease severity and designing suitable therapy for management of human chagasic patients.

Vaccine development against Trypanosoma cruzi and Chagas disease

The pathology of Chagas disease presents a complicated and diverse picture in humans. The major complications and destructive evolutionary outcomes of chronic infection by Trypanosoma cruzi in humans include ventricular fibrillation, thromboembolism and congestive heart failure. Studies in animal models and human patients have revealed the pathogenic mechanisms during disease progression, pathology of disease and features of protective immunity. Accordingly, several antigens, antigen-delivery vehicles and adjuvants have been tested to elicit immune protection to T. cruzi in experimental animals. This review summarizes the research efforts in vaccine development against Chagas disease during the past decade.

[Regional left ventricular dysfunction and its association with complex ventricular arrhythmia, in chagasic patients with normal or borderline electrocardiogram]

INTRODUCTION

Sudden death is the major cause of death among chagasic patients. A significant number of fatal events in patients without apparent heart disease and borderline electrocardiogram, but with contractile ventricular dysfunction, have been documented. This work aimed to determine the association between regional dysfunction and the presence of ventricular arrhythmia in chagasic patients without apparent heart disease.

METHODS

Forty-nine patients with normal or borderline electrocardiogram were submitted to echocardiogram, exercise stress test and Holter. The presence of cardiac contractile alterations and complex ventricular arrhythmia was analyzed. Statistic analysis used the general Log-Linear model.

RESULTS

Mean age 56 years-old; 55% women. Regional ventricular dysfunction was verified in 24.5% of patients; positive Holter in 12% and exercise stress test in 18%. An association between complex ventricular arrhythmia and contractile abnormalities in the presence of mild left ventricle dysfunction was verified.

CONCLUSIONS

Regional contractile abnormalities with mild left ventricle dysfunction in Chagasic patients indicate a group with higher risk of complex ventricular arrhythmias, who require specific follow-up.

Would selenium supplementation aid in therapy for Chagas disease?

Chagas disease, a neglected tropical disease discovered over 100 years ago, is caused by the intracellular parasite Trypanosoma cruzi and is most frequently associated with chronic cardiomyopathy and digestive disorders. Initial invasion of cells is followed by progressive inflammatory destruction of heart, muscles, nerves, and gastrointestinal (GI) tract tissue. Approximately 30% of patients progress to a chronic cardiomyopathy associated with increased morbidity and mortality. Seven to 10% of patients develop megasyndromes involving the GI tract, in particular, the esophagus and the colon. Results from several studies suggest that selenium (Se) deficiency could be an important factor in the pathogenesis of Chagas disease. In this opinion article, Se supplementation is proposed as an adjuvant therapy for treatment of chronic Chagas disease.

ROS signalling of inflammatory cytokines during Trypanosoma cruzi infection

Inflammation is a host defence activated by exogenous (e.g. pathogen-derived, pollutants) or endogenous (e.g. reactive oxygen species-ROS) danger signals. Mostly, endogenous molecules (or their derivatives) have well-defined intracellular function but become danger signal when released or exposed following stress or injury. In this review, we discuss the potential role of ROS in chronic evolution of inflammatory cardiovascular diseases, using our experiences working on chagasic cardiomyopathy as a focus-point.

Increase of reactive oxygen species by desferrioxamine during experimental Chagas' disease

Oxidative stress is common in inflammatory processes associated with many diseases including Chagas' disease. The aim of the present study was to evaluate, in a murine model, biomarkers of oxidative stress together with components of the antioxidant system in order to provide an overview of the mechanism of action of the iron chelator desferrioxamine (DFO). The study population comprised 48 male Swiss mice, half of which were treated daily by intraperitoneal injection of DFO over a 35-day period, while half were administered sterile water in a similar manner. On the 14th day of the experiment, 12 DFO-treated mice and an equal number of untreated mice were experimentally infected with Trypanosoma cruzi. Serum concentrations of nitric oxide and superoxide dismutase and hepatic levels of total glutathione, thiobarbituric acid reactive species and protein carbonyl, were determined on days 0, 7, 14 and 21 post-infection. The results obtained revealed that DFO enhances antioxidant activity in the host but also increases oxidative stress, indicating that the mode of action of the drug involves a positive contribution to the host together with an effect that is not beneficial to the parasite.

Phenyl-alpha-tert-butyl-nitrone and benzonidazole treatment controlled the mitochondrial oxidative stress and evolution of cardiomyopathy in chronic chagasic Rats

OBJECTIVES

The purpose of this study was to determine the pathological importance of oxidative stress-induced injurious processes in chagasic heart dysfunction.

BACKGROUND

Trypanosoma cruzi-induced inflammatory pathology and a feedback cycle of mitochondrial dysfunction and oxidative stress may contribute to Chagas disease.

METHODS

Sprague-Dawley rats were infected with T. cruzi and treated with phenyl-alpha-tert-butylnitrone (PBN), an antioxidant, and/or benzonidazole (BZ), an antiparasitic agent. We monitored myocardial parasite burden, oxidative adducts, mitochondrial complex activities, respiration, and adenosine triphosphate synthesis rates, and inflammatory and cardiac remodeling responses during disease development. The cardiac hemodynamics was determined for all rats.

RESULTS

Benzonidazole (not PBN) decreased the parasite persistence and immune adverse events (proinflammatory cytokine expression, beta-nicotinamide adenine dinucleotide phosphate oxidase and myeloperoxidase activities, and inflammatory infiltrate) in chronically infected hearts. PBN +/- BZ (not BZ alone) decreased the mitochondrial reactive oxygen species level, oxidative adducts (malonyldialdehyde, 4-hydroxynonenal, carbonyls), hypertrophic gene expression (atrial natriuretic peptide, B-type natriuretic peptide, alpha-skeletal actin), and collagen deposition and preserved the respiratory chain efficiency and energy status in chronically infected hearts. Subsequently, LV dysfunction was prevented in PBN +/- BZ-treated chagasic rats.

CONCLUSIONS

BZ treatment after the acute stage decreased the parasite persistence and inflammatory pathology. Yet, oxidative adducts, mitochondrial dysfunction, and remodeling responses persisted and contributed to declining cardiac function in chagasic rats. Combination treatment (PBN + BZ) was beneficial in arresting the T. cruzi-induced inflammatory and oxidative pathology and chronic heart failure in chagasic rats.

Trypanosoma cruzi induces the reactive oxygen species-PARP-1-RelA pathway for up-regulation of cytokine expression in cardiomyocytes

In this study, we demonstrate that human cardiomyocytes (AC16) produce reactive oxygen species (ROS) and inflammatory cytokines in response to Trypanosoma cruzi. ROS were primarily produced by mitochondria, some of which diffused to cytosol of infected cardiomyocytes. These ROS resulted in an increase in 8-hydroxyguanine lesions and DNA fragmentation that signaled PARP-1 activation evidenced by poly(ADP-ribose) (PAR) modification of PARP-1 and other proteins in infected cardiomyocytes. Phenyl-alpha-tert-butylnitrone blocked the mitochondrial ROS (mtROS) formation, DNA damage, and PARP-1 activation in infected cardiomyocytes. Further inhibition studies demonstrated that ROS and PARP-1 signaled TNF-alpha and IL-1beta expression in infected cardiomyocytes. ROS directly signaled the nuclear translocation of RelA (p65), NF-kappaB activation, and cytokine gene expression. PARP-1 exhibited no direct interaction with p65 and did not signal its translocation to nuclei in infected cardiomyocytes. Instead, PARP-1 contributed to PAR modification of p65-interacting nuclear proteins and assembly of the NF-kappaB transcription complex. PJ34 (PARP-1 inhibitor) also prevented mitochondrial poly(ADP-ribosyl)ation (PARylation) and ROS formation. We conclude that T. cruzi-mediated mtROS provide primary stimulus for PARP-1-NF-kappaB activation and cytokine gene expression in infected cardiomyocytes. PAR modification of mitochondrial membranes then results in a feedback cycle of mtROS formation and DNA damage/PARP-1 activation. ROS, either through direct modulation of cytosolic NF-kappaB, or via PARP-1-dependent PAR modification of p65-interacting nuclear proteins, contributes to cytokine gene expression. Our results demonstrate a link between ROS and inflammatory responses in cardiomyocytes infected by T. cruzi and provide a clue to the pathomechanism of sustained inflammation in Chagas disease.