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Disorders of gastrointestinal motility are the major physiologic problem in chagasic megacolon. The contraction mechanism is complex and controlled by different cell types such as enteric neurons, smooth muscle, telocytes, and an important pacemaker of the intestine, the interstitial cells of Cajal (ICCs). The role of ICCs in the progression of acute and chronic Chagas disease remains unclear. In the present work, we investigate the aspects of ICCs in a long-term model of Chagas disease that mimics the pathological aspects of human megacolon. Different subsets of ICCs isolated from Auerbach's myenteric plexuses and muscle layers of control and Trypanosoma cruzi infected animals were determined by analysis of CD117, CD44, and CD34 expression by flow cytometer. Compared with the respective controls, the results showed a reduced frequency of mature ICCs in the acute phase and three months after infection. These results demonstrate for the first time the phenotypic distribution of ICCs associated with functional dysfunction in a murine model of chagasic megacolon. This murine model proved valuable for studying the profile of ICCs as an integrative system in the gut and as a platform for understanding the mechanism of chagasic megacolon development.

Over 110 years after the first formal description of Chagas disease, the trypanocidal drugs thus far available have limited efficacy and several side effects. This encourages the search for novel treatments that inhibit T. cruzi targets. One of the most studied anti-T. cruzi targets is the cysteine protease cruzain; it is associated with metacyclogenesis, replication, and invasion of the host cells. We used computational techniques to identify novel molecular scaffolds that act as cruzain inhibitors. First, with a docking-based virtual screening, we identified compound 8, a competitive cruzain inhibitor with a K i of 4.6 μM. Then, aided by molecular dynamics simulations, cheminformatics, and docking, we identified the analog compound 22 with a K i of 27 μM. Surprisingly, despite sharing the same isoquinoline scaffold, compound 8 presented higher trypanocidal activity against the epimastigote forms, while compound 22, against the trypomastigotes and amastigotes. Taken together, compounds 8 and 22 represent a promising scaffold for further development of trypanocidal compounds as drug candidates for treating Chagas disease., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Rafaela Salgado Ferreira reports financial support was provided by Minas Gerais State Foundation of Support to the Research (FAPEMIG). Rafaela Salgado Ferreira reports financial support was provided by National Council for Scientific and Technological Development (CNPq). Rafaela Salgado Ferreira reports financial support was provided by Coordination of Higher Education Personnel Improvement (CAPES). Viviane Corrêa Santos reports financial support was provided by National Council for Scientific and Technological Development. Viviane Corrêa Santos reports financial support was provided by Coordination of Higher Education Personnel Improvement. Peter Kolb reports financial support was provided by German Research Foundation DFG. Rafaela Salgado Ferreira has patent #BR102022002935 pending to INPI - Instituto Nacional da Propriedade Industrial., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

Chagas disease has a complex pathogenesis wherein the host immune response is essential for controlling its development. Suppressor of cytokine signaling(SOCS)2 is a crucial protein that regulates cytokine production. In this study, SOCS2 deficiency resulted in an initial imbalance of IL12- and IL-10-producing neutrophils and dendritic cells (DCs), which caused a long-lasting impact reducing inflammatory neutrophils and DCs, and tolerogenic DCs at the peak of acute disease. A reduced number of inflammatory and pro-resolving macrophages, and IL17A-producing CD4 + T cells, and increased lymphocyte apoptosis was found in SOCS2-deficient mice. Electrocardiogram analysis of chimeric mice showed that WT mice that received SOCS2 KO bone marrow transplantation presented increased heart dysfunction. Taken together, the results demonstrated that SOCS2 is a crucial regulator of the immune response during Trypanosoma cruzi infection, and suggest that a SOCS2 genetic polymorphism, or failure of its expression, may increase the susceptibility of cardiomyopathy development in Chagasic patients., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Current chemical therapies for Chagas Disease (CD) lack ability to clear Trypanosoma cruzi (Tc) parasites and cause severe side effects, making search for new strategies extremely necessary. We evaluated the action of Tityus serrulatus venom (TsV) components during Tc infection. TsV treatment increased nitric oxide and pro-inflammatory cytokine production by Tc-infected macrophages (MØ), decreased intracellular parasite replication and trypomastigotes release, also triggering ERK1/2, JNK1/2 and p38 activation. Ts7 demonstrated the highest anti-Tc activity, inducing high levels of TNF and IL-6 in infected MØ. TsV/Ts7 presented synergistic effect on p38 activation when incubated with Tc antigen. KPP-treatment of MØ also decreased trypomastigotes releasing, partially due to p38 activation. TsV/Ts7-pre-incubation of Tc demonstrated a direct effect on parasite decreasing MØ-trypomastigotes releasing. In vivo KPP-treatment of Tc-infected mice resulted in decreased parasitemia. Summarizing, this study opens perspectives for new bioactive molecules as CD-therapeutic treatment, demonstrating the TsV/Ts7/KPP-trypanocidal and immunomodulatory activity during Tc infection., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in controlling several aspects of immune responses, including the activation and differentiation of specific T cell subsets and antigen-presenting cells, thought to be relevant in the context of experimental Trypanosoma cruzi infection. The relevance of AhR for the outcome of T. cruzi infection is not known and was investigated here. We infected wild-type (WT) mice and AhR knockout (AhR KO) mice with T. cruzi (Y strain) and determined levels of parasitemia, myocardial inflammation and fibrosis, expression of AhR/cytokines/suppressor of cytokine signaling (SOCS) (spleen/heart), and production of nitric oxide (NO), reactive oxygen species (ROS), and peroxynitrite (ONOO(-)) (spleen). AhR expression was increased in the heart of infected WT mice. Infected AhR KO mice displayed significantly reduced parasitemia, inflammation, and fibrosis of the myocardium. This was associated with an anticipated increased immune response characterized by increased levels of inflammatory cytokines and reduced expression of SOCS2 and SOCS3 in the heart. In vitro, AhR deficiency caused impairment in parasite replication and decreased levels of ROS production. In conclusion, AhR influences the development of murine Chagas disease by modulating ROS production and regulating the expression of key physiological regulators of inflammation, SOCS1 to -3, associated with the production of cytokines during experimental T. cruzi infection., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Over 100 years have elapsed since the discovery of Chagas disease and there is still much to learn regarding pathogenesis and treatment. Although there are antiparasitic drugs available, such as benznidazole and nifurtimox, they are not totally reliable and often toxic. A recently released negative clinical trial with benznidazole in patients with chronic Chagas cardiomyopathy further reinforces the concerns regarding its effectiveness. New drugs and new delivery systems, including those based on nanotechnology, are being sought. Although vaccine development is still in its infancy, the reality of a therapeutic vaccine remains a challenge. New ECG methods may help to recognize patients prone to developing malignant ventricular arrhythmias. The management of heart failure, stroke and arrhythmias also remains a challenge. Although animal experiments have suggested that stem cell based therapy may be therapeutic in the management of heart failure in Chagas cardiomyopathy, clinical trials have not been promising.

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.

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.

Chagas disease, caused by Trypanosoma cruzi (Tc), is an important cause of heart disease. Resistance to Tc infection is multifactorial and associated with Th1 response. IL-18 plays an important role in regulation of IFN-γ production/development of Th1 response. However, the role of IL-18 in the setting of Tc infection remains unclear. Therefore, we investigated the role of IL-18 in the modulation of immune response and myocarditis in Tc infection. C57BL/6 and IL-18 KO mice were infected with Tc (Y or Colombian strain) and parasitemia, immune response and pathology were evaluated. Y strain infection of IL-18 KO did not alter any parameters when compared with C57BL/6 mice. However, during the acute phase (20 and 40 days post infection-dpi), Colombian strain infected-IL-18 KO mice displayed higher serum levels of IL-12 and IFN-γ, respectively, and at the chronic phase (100 dpi) an increase in splenic IFN-γ-producing CD4(+) and CD8(+) T memory cells. There was an IL-10, FOXP3 and CD4(+)CD25(+) cells reduction during acute infection in spleen. Additionally, there was a significant reduction in leukocyte infiltration and parasite load in myocardium of chronically infected IL-18 KO mice. Collectively, these data indicate that IL-18 contributes to the pathogenesis of Tc-induced myocarditis when infected with Colombian but not Y strain. These observations also underscore that parasite and host strain differences are important in evaluation of experimental Tc infection pathogenesis., (Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Trypanosoma cruzi infects all nucleated cells in both humans and experimental animals. As a prelude to our studies of T. cruzi pathogenesis in the gastrointestinal system, we have initiated in vitro cultures of gut (Caco-2 and HT-29) and pancreatic (Panc-1) epithelial cells. We show that along with primary human fibroblasts, all three cell lines are susceptible to infection and support proliferation of T. cruzi. Infection with T. cruzi modified dramatically the cytokines elaborated by these cells. Substantially greater quantities of IL-5 and TGF-β1 were produced by fibroblasts and Caco-2 and Panc-1 cells, whereas secretion of IFN-γ and TNF-α was greatly reduced in all three cell types. Since these cells are not known to be the primary sources of IFN-γ, we examined IFN-γ mRNA expression in these cells. Both Caco-2 and Panc-1 cells were found to express IFN-γ mRNA, validating its secretion. These findings may provide insight into signaling pathways that mediate innate immunity to T. cruzi and pathogenesis of gastrointestinal and pancreatic alterations in Chagas disease.

Chagas disease, caused by Trypanosoma cruzi, is an important cause of morbidity and mortality primarily resulting from cardiac dysfunction, although T. cruzi infection results in inflammation and cell destruction in many organs. We found that T. cruzi (Brazil strain) infection of mice results in pancreatic inflammation and parasitism within pancreatic β-cells with apparent sparing of α cells and leads to the disruption of pancreatic islet architecture, β-cell dysfunction, and surprisingly, hypoglycemia. Blood glucose and insulin levels were reduced in infected mice during acute infection and insulin levels remained low into the chronic phase. In response to the hypoglycemia, glucagon levels 30 days postinfection were elevated, indicating normal α-cell function. Administration of L-arginine and a β-adrenergic receptor agonist (CL316, 243, respectively) resulted in a diminished insulin response during the acute and chronic phases. Insulin granules were docked, but the lack of insulin secretion suggested an inability of granules to fuse at the plasma membrane of pancreatic β-cells. In the liver, there was a concomitant reduced expression of glucose-6-phosphatase mRNA and glucose production from pyruvate (pyruvate tolerance test), demonstrating defective hepatic gluconeogenesis as a cause for the T. cruzi-induced hypoglycemia, despite reduced insulin, but elevated glucagon levels. The data establishes a complex, multi-tissue relationship between T. cruzi infection, Chagas disease, and host glucose homeostasis., (Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

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.

Trypanosoma cruzi infection leads to development of chronic Chagas disease. In this article, we provide an update on the current knowledge of the mechanisms employed by the parasite to gain entry into the host cells and establish persistent infection despite activation of a potent immune response by the host. Recent studies point to a number of T. cruzi molecules that interact with host cell receptors to promote parasite invasion of the diverse host cells. T. cruzi expresses an antioxidant system and thromboxane A(2) to evade phagosomal oxidative assault and suppress the host's ability to clear parasites. Additional studies suggest that besides cardiac and smooth muscle cells that are the major target of T. cruzi infection, adipocytes and adipose tissue serve as reservoirs from where T. cruzi can recrudesce and cause disease decades later. Further, T. cruzi employs at least four strategies to maintain a symbiotic-like relationship with the host, and ensure consistent supply of nutrients for its own survival and long-term persistence. Ongoing and future research will continue to help refining the models of T. cruzi invasion and persistence in diverse tissues and organs in the host., (© 2012 Blackwell Publishing Ltd.)

Brown adipose tissue (BAT) and white adipose tissue (WAT) and adipocytes are targets of Trypanosoma cruzi infection. Adipose tissue obtained from CD-1 mice 15 days after infection, an early stage of infection revealed a high parasite load. There was a significant increase in macrophages in infected adipose tissue and a reduction in lipid accumulation, adipocyte size, and fat mass and increased expression of lipolytic enzymes. Infection increased levels of Toll-like receptor (TLR) 4 and TLR9 and in the expression of components of the mitogen-activated protein kinase pathway. Protein and messenger RNA (mRNA) levels of peroxisome proliferator-activated receptor γ were increased in WAT, whereas protein and mRNA levels of adiponectin were significantly reduced in BAT and WAT. The mRNA levels of cytokines, chemokines, and their receptors were increased. Nuclear Factor Kappa B levels were increased in BAT, whereas Iκκ-γ levels increased in WAT. Adipose tissue is an early target of T. cruzi infection.

Trypanosoma cruzi is the etiologic agent of Chagas disease. The contributions of parasite and immune system for disease pathogenesis remain unresolved and controversial. The possibility that Chagas disease was an autoimmune progression triggered by T. cruzi infection led some to question the benefit of treating chronically T. cruzi-infected persons with drugs. Furthermore, it provided the rationale for not investing in research aimed at a vaccine which might carry a risk of inducing autoimmunity or exacerbating inflammation. This viewpoint was adopted by cash-strapped health systems in the developing economies where the disease is endemic and has been repeatedly challenged by researchers and clinicians in recent years and there is now a considerable body of evidence and broad consensus that parasite persistence is requisite for pathogenesis and that antiparasitic immunity can be protective against T. cruzi pathogenesis without eliciting autoimmune pathology. Thus, treatment of chronically infected patients is likely to yield positive outcomes and efforts to understand immunity and vaccine development should be recognized as a priority area of research for Chagas disease.

Trypanosoma cruzi, the etiological agent of Chagas disease, causes vasculopathy and cardiomyopathy in humans and is associated with elevated levels of several vasoactive molecules such as nitric oxide, endothelin-1 and thromboxane A 2 (TXA 2). Parasite derived TXA 2 modulates vasculopathy and other pathophysiological features of Chagasic cardiomyopathy. Previously, we demonstrated that in response to infection with T. cruzi, TXA 2 receptor (TP) null mice displayed increased parasitemia; mortality and cardiac pathology compared with wild type (WT) and TXA 2 synthase null mice. In order to further study the role of TXA 2-TP signaling in the development of Chagas disease, GeneChip microarrays were used to detect transcriptome changes in rat fat pad endothelial cells (RFP-ECs) which is incapable of TXA 2 signaling (TP null) to that of control (wild type) and RFP-EC with reconstituted TP expression. Genes that were significantly regulated due to infection were identified using a time course of 2, 18 and 48 hrs post infection. We identified several key genes such as suppressor of cytokine signaling (SOCS-5), several cytokines (CSF-1, CXCF ligands), and MAP kinases (MAPK-1, Janus kinase) that were upregulated in the absence of TP signaling. These data underscore the importance of the interaction of the parasite with mammalian TP and may explain the increased mortality and cardiovascular pathology observed in infected TP null mice.

Chagas disease, caused by infection with Trypanosoma cruzi, is an important cause of cardiovascular disease. It is increasingly clear that parasite-derived prostaglandins potently modulate host response and disease progression. Here, we report that treatment of experimental T. cruzi infection (Brazil strain) beginning 5 days post infection (dpi) with aspirin (ASA) increased mortality (2-fold) and parasitemia (12-fold). However, there were no differences regarding histopathology or cardiac structure or function. Delayed treatment with ASA (20 mg/kg) beginning 60 dpi did not increase parasitemia or mortality but improved ejection fraction. ASA treatment diminished the profile of parasite- and host-derived circulating prostaglandins in infected mice. To distinguish the effects of ASA on the parasite and host bio-synthetic pathways we infected cyclooxygenase-1 (COX-1) null mice with the Brazil-strain of T. cruzi. Infected COX-1 null mice displayed a reduction in circulating levels of thromboxane (TX)A(2) and prostaglandin (PG)F(2α). Parasitemia was increased in COX-1 null mice compared with parasitemia and mortality in ASA-treated infected mice indicating the effects of ASA on mortality potentially had little to do with inhibition of prostaglandin metabolism. Expression of SOCS-2 was enhanced, and TRAF6 and TNFα reduced, in the spleens of infected ASA-treated mice. Ablation of the initial innate response to infection may cause the increased mortality in ASA-treated mice as the host likely succumbs more quickly without the initiation of the "cytokine storm" during acute infection. We conclude that ASA, through both COX inhibition and other "off-target" effects, modulates the progression of acute and chronic Chagas disease. Thus, eicosanoids present during acute infection may act as immunomodulators aiding the transition to and maintenance of the chronic phase of the disease. A deeper understanding of the mechanism of ASA action may provide clues to the differences between host response in the acute and chronic T. cruzi infection.

Chagas disease is caused by Trypanosoma cruzi, a protozoan parasite. Chagas disease remains a serious health problem in large parts of Mexico and Central and South America, where it is a major cause of morbidity and mortality. This disease is being increasingly recognized in non-endemic regions due to immigration. Heart disease develops in 10-30% of infected individuals. It is increasingly clear that parasite- and host-derived bioactive lipids potently modulate disease progression. Many of the changes that occur during acute and chronic Chagas disease can be accounted for by the effects of arachidonic acid (AA)-derived lipids such as leukotrienes, lipoxins, H(P)ETEs, prostaglandins (PGs) and thromboxane. During the course of infection with T. cruzi, changes in circulating levels of AA metabolites are observed. Antagonism of PG synthesis with cyclooxygenase (COX) inhibitors has both beneficial and adverse effects. Treatment with COX inhibitors during acute infection may result in increased parasite load and mortality. However, treatment instituted during chronic infection may be beneficial with no increase in mortality and substantial improvement with cardiac function. Recently, T. cruzi infection of mice deficient in AA biosynthetic enzymes for various pathways has yielded more insightful data than pharmacological inhibition and has highlighted the potential deleterious effects of inhibitors due to "off-target" actions. Using COX-1 null mice, it was observed that parasite biosynthesis is dependent upon host metabolism, that the majority of TXA(2) liberated during T. cruzi infection is derived from the parasite and that this molecule may act as a quorum sensor to control parasite growth/differentiation. Thus, eicosanoids present during acute infection may act as immunomodulators aiding the transition to, and maintenance of, the chronic stage of the disease. It is also likely that the same mediators that initially function to ensure host survival may later contribute to cardiovascular damage. Collectively, the eicosanoids represent a new series of targets for therapy in Chagas disease with defined potential therapeutic windows in which to apply these agents for greatest effect. A deeper understanding of the mechanism of action of non-steroidal anti-inflammatory drugs may provide clues to the differences between host responses in acute and chronic T. cruzi infection., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Adipose tissue is the largest endocrine organ in the body and is composed primarily of adipocytes (fat cells) but also contains fibroblasts, endothelial cells, smooth muscle cells, macrophages and lymphocytes. Adipose tissue and the adipocyte are important in the regulation of energy metabolism and of the immune response. Adipocytes also synthesize adipokines such as adiponectin which is important in the regulation of insulin sensitivity and inflammation. Infection of mice with Trypanosoma cruzi results in an upregulation of inflammation in adipose tissue that begins during the acute phase of infection and persists into the chronic phase. The adipocyte is both a target of infection and a reservoir for the parasite during the chronic phase from which recrudescence of the infection may occur during periods of immunosuppression., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Mice carrying a defective leptin receptor gene (db/db mice) are metabolically challenged and upon infection with Trypanosoma cruzi (Brazil strain) suffer high mortality. In genetically modified db/db mice, (NSE-Rb db/db mice), central leptin signaling is reconstituted only in the brain, which is sufficient to correct the metabolic defects. NSE-Rb db/db mice were infected with T. cruzi to determine the impact of the lack of leptin signaling on infection in the absence of metabolic dysregulation. Parasitemia levels, mortality rates, and tissue parasitism were statistically significantly increased in infected db/db mice compared with those in infected NSE-Rb db/db and FVB wild-type mice. There was a reduction in fat mass and blood glucose level in infected db/db mice. Plasma levels of several cytokines and chemokines were statistically significantly increased in infected db/db mice compared with those in infected FVB and NSE-Rb db/db mice. These findings suggest that leptin resistance in individuals with obesity and diabetes mellitus may have adverse consequences in T. cruzi infection.

Chagas' disease (CD) is caused by the protozoan Trypanosoma cruzi (Tc) and remains an important cause of morbidity and mortality. Most researchers in the field now agree that chronic low grade parasite persistence in tissue drives tissue damage and the autoimmune component of CD. Current therapy relies on two compounds: benznidazole and nifurtimox. Despite their long history in the treatment of CD, both compounds induce significant side-effects. In the current issue of the BJP, two contributions demonstrate that NO-donors are active, especially in combination with benznidazole, against Tc in vitro and in experimental models in vivo. The basic concept used by the authors to develop novel anti-Tc compounds relied on the demonstrated ability of nitric oxide to kill the parasite. There are several issues still to be resolved but the reported studies are a clear advance to the field and should be considered for further pre-clinical development.

Caveolae are motile, membrane-bound compartments that contain a number of molecules that participate in cell signaling. Caveolins are protein markers of caveolae and function in a variety of biological processes. Caveolin-3 (Cav-3) is expressed in muscle cells and Cav-3 null mice display a cardiomyopathic phenotype. Ultrastructural cytochemistry, confocal microscopy and immunoblotting revealed a reduction in Cav-3 expression and an activation of ERK (extracellular-signal-regulated kinase) 48 hours after Trypanosoma cruzi infection of cultured cardiac myocytes. CD-1 mice infected with the Brazil strain of T. cruzi displayed reduced expression of Cav-3 and activation of ERK 66 days post infection (dpi).   By 180 dpi there was a normalization of these values. These data suggest that the reduction in Cav-3 expression and the activation of ERK during the early phase of infection may contribute to the pathogenesis of chagasic cardiomyopathy.

Trypanosoma cruzi infection of the adipose tissue of mice triggers the local expression of inflammatory mediators and a reduction in the expression of the adipokine adiponectin. T. cruzi can be detected in adipose tissue by PCR 300 days post-infection. Infection of cultured adipocytes results in increased expression of cytokines and chemokines and a reduction in the expression of adiponectin and the peroxisome proliferator-activated receptor gamma, both of which are negative regulators of inflammation. Infection also results in the upregulation of cyclin D1, the Notch pathway, and extracellular signal-regulated kinase and a reduction in the expression of caveolin-1. Thus, T. cruzi infection of cultured adipocytes leads to an upregulation of the inflammatory process. Since adiponectin null mice have a cardiomyopathic phenotype, it is possible that the reduction in adiponectin contributes to the pathogenesis of chagasic cardiomyopathy. Adipose tissue may serve as a reservoir for T. cruzi from which parasites can become reactivated during periods of immunosuppression. T. cruzi infection of mice often results in hypoglycemia. In contrast, hyperglycemia as observed in diabetes results in increased parasitemia and mortality. Adipose tissue is an important target tissue of T. cruzi and the infection of this tissue is associated with a profound impact on systemic metabolism, increasing the risk of metabolic syndrome.

Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets.

Infection with Trypanosoma cruzi causes megasyndromes of the gastrointestinal (GI) tract. We used magnetic resonance imaging (MRI) to monitor alterations in the GI tract of T. cruzi-infected mice, and to assess the role of nitric oxide (NO) in the development of intestinal dilation. Brazil strain-infected C57BL/6 wild-type (WT) mice exhibited dilatation of the intestines by 30 days post-infection. Average intestine lumen diameter increased by 72%. Levels of intestinal NO synthase (NOS) isoforms, NOS2 and NOS3, were elevated in infected WT mice. Inflammation and ganglionitis were observed in all infected mice. Intestinal dilation was observed in infected WT, NOS1, NOS2, and NOS3 null mice. This study demonstrates that MRI is a useful tool to monitor intestinal dilation in living mice and that these alterations may begin during acute infection. Furthermore, our data strongly suggests that NO may not be the sole contributor to intestinal dysfunction resulting from this infection.

Infection with the parasite Trypanosoma cruzi causes Chagas disease. In this study we demonstrated that there was an increase in cyclin D1 expression in T. cruzi (Tulahuen strain)-infected myoblasts. To examine a possible mechanism for the increased cyclin D1 expression we transfected L(6)E(9) myoblasts with cyclin D1 luciferase reporter constructs and infected with T. cruzi. There was no evidence of an increase in promoter activity. Additionally, quantitative PCR did not demonstrate any change in cyclin D1 message during infection. Moreover, we demonstrated that the cyclin D1 protein was significantly stabilized after infection. Collectively, these data indicate that infection with T. cruzi increases cyclin D1 protein abundance post-translationally.

In this chapter we summarize the protective and toxic effects of nitric oxide (NO) that are frequently seen in parallel during the infection with Trypanosoma cruzi. The killing of trypomastigotes is dependent on the production of NO which is catalyzed by the inducible NO synthase (iNOS). The cytokines IFN-gamma and TNF-alpha and several chemoatractants molecules, which act on G protein-coupled serpentine receptors, are produced during the acute infection. They play major roles in the induction of iNOS, and in the NO production-dependent killing of T. cruzi by murine macrophages. On the other hand, TGF-beta and IL-10, which are also produced during the infection, are negative regulators of NO production. In addition to mediating resistance against the infection, NO can also suppress the immune response to T. cruzi via the induction of apoptosis of T cells. Furthermore, the expression of cardiac iNOS has been associated with myocardial dysfunction. In fact, we discuss here the evidences indicating that iNOS/NO pathway is involved in the pathogenesis of neuronal and myocardial dysfunction seen in patients and in experimental models.

Objective: To determine the value of the radiological study of the thorax for diagnosing left ventricular dilation and left ventricular systolic dysfunction in patients with Chagas' disease., Methods: A cross-sectional study of 166 consecutive patients with Chagas' disease and no other associated diseases. The patients underwent cardiac assessment with chest radiography and Doppler echocardiography. Sensitivity, specificity, and positive and negative predictive values of chest radiography were calculated to detect left ventricular dysfunction and the accuracy of the cardiothoracic ratio in the diagnosis of left ventricular dysfunction with the area below the ROC curve. The cardiothoracic ratio was correlated with the left ventricular ejection fraction and the left ventricular diastolic diameter., Results: The abnormal chest radiogram had a sensitivity of 50%, specificity of 80.5%, and positive and negative predictive values of 51.2% and 79.8%, respectively, in the diagnosis of left ventricular dysfunction. The cardiothoracic ratio showed a weak correlation with left ventricular ejection fraction (r=-0.23) and left ventricular diastolic diameter (r=0.30). The area calculated under the ROC curve was 0.734., Conclusion: The radiological study of the thorax is not an accurate indicator of left ventricular dysfunction; its use as a screening method to initially approach the patient with Chagas' disease should be reevaluated.

Objective: To assess the usefulness of Doppler tissue imaging (DTI) for evaluating the systolic function of chagasic patients with and without electrocardiographic abnormalities, in comparision with echocardiographic study., Methods: We studied 77 patients divided into 3 groups as follows: group 1 - control; group 2 - chagasic patients with normal electrocardiographic findings; and group 3 - chagasic patients with abnormal electrocardiographic findings. The following parameters were assessed: left ventricular dimensions and ejection fraction, left atrial dimensions and diastolic function on echocardiography. Systolic velocity and regional isovolumic contraction time (IVCTr) of the septal, anterior, lateral, posterior and inferior left ventricular walls were assessed on DTI., Results: Left ventricular cavitary dimensions, ejection fraction and DTI systolic wave showed significant differences between groups 1 and 3 and between groups 2 and 3, which were not found between groups 1 and 2. IVCTr allowed a statistically significant discrimination among the 3 groups., Conclusion: DTI allowed discrimination among the different groups assessed, being superior to echocardiography in identifying early abnormalities of contractility, and, therefore, potentially useful for detecting incipient myocardial alterations in chagasic patients with normal electrocardiographic findings.

Background: The involvement of the right ventricle (RV) in Chagas' disease is frequent. Although echocardiography plays an important role in noninvasive assessment of cardiac function, evaluation of RV is challenging because of the anatomic and functional complexity of this chamber., Methods: To study early functional abnormalities in the RV, we selected 18 patients with Chagas' disease, no other disease, and a normal echocardiogram; and 12 normal individuals as a control group. All participants were submitted to Doppler tissue imaging and the parameters of systolic (systolic wave and regional isovolumic contraction time) and diastolic (early and late expansion waves) function were analyzed at the level of the interventricular septum and free wall of the RV., Results: Regional isovolumic contraction time values showed a statistically significant difference between the 2 groups both in the RV free (P =.0003) and septal (P =.003) walls. With respect to diastolic function, we observed a significant difference between groups involving the early expansion wave (P =.014) and e/a ratio (P =.004) of the RV free wall., Conclusion: Doppler tissue imaging proved to be useful in early detection of RV dysfunction in Chagas' disease, with potential use in risk stratification of these patients.

Left ventricular dysfunction in Chagas' disease is common but can be difficult to detect. We investigated whether measurement of plasma brain natriuretic peptide (BNP) could identify patients with left ventricular dysfunction who need further investigation or treatment. Among patients with an abnormal electrocardiogram or chest radiograph, a BNP concentration of 60.7 pmol/L or higher has a sensitivity and positive predictive value of 80%, and specificity and negative predictive value of 97%. Measurement of plasma BNP concentration could be a useful method to screen patients with Chagas' disease.

The production of nitric oxide (NO) by gamma interferon (IFN-gamma)-activated macrophages is a major effector mechanism during experimental Trypanosoma cruzi infection. In addition to IFN-gamma, chemoattractant molecules, such as platelet-activating factor (PAF) and CC chemokines, may also activate macrophages to induce NO and mediate the killing of T. cruzi in an NO-dependent manner. Here we investigated the ability of leukotriene B(4) (LTB(4)) to induce the production of NO by macrophages infected with T. cruzi in vitro and whether NO mediated LTB(4)-induced parasite killing. The activation of T. cruzi-infected but not naive murine peritoneal macrophages with LTB(4) induced the time- and concentration-dependent production of NO. In addition, low concentrations of LTB(4) acted in synergy with IFN-gamma to induce NO production. The NO produced mediated LTB(4)-induced microbicidal activity in macrophages, as demonstrated by the inhibitory effects of an inducible NO synthase inhibitor. LTB(4)-induced NO production and parasite killing were LTB(4) receptor dependent and were partially blocked by a PAF receptor antagonist. LTB(4) also induced significant tumor necrosis factor alpha (TNF-alpha) production, and blockade of TNF-alpha suppressed LTB(4)-induced NO release and parasite killing. A blockade of LTB(4) or PAF receptors partially inhibited IFN-gamma-induced NO and TNF-alpha production but not parasite killing. Finally, daily treatment of infected mice with CP-105,696 was accompanied by a significantly higher level of blood parasitemia, but not lethality, than that seen in vehicle-treated animals. In conclusion, our results suggest a role for LTB(4) during experimental T. cruzi infection. Chemoattractant molecules such as LTB(4) not only may play a major role in leukocyte migration into sites of inflammation in vivo but also, in the event of an infection, may play a relevant role in the activation of recruited leukocytes to kill the invading microorganism in an NO-dependent manner.

During acute Trypanosoma cruzi infection in mice, many leucocytes undergo apoptosis. Although apoptosis has been ascribed to increased levels of nitric oxide (NO) and Fas-FasL interaction, the importance of this phenomenon in modulating the host response against T. cruzi is unknown. Herein, the role of NO- and Fas-FasL-induced apoptosis in modulating the immune response to T. cruzi was evaluated using mice deficient in Fas expression (MRL/MpJ-Fas lpr) and inducible nitric oxide synthase (iNOS) knockout mice (iNOS-/-). The results showed that besides decreasing apoptosis induction after infection, impairment of the Fas-FasL interaction resulted in decreased NO production, as a consequence of enhanced T helper 2 (Th2) cytokine production. Differently, blockage of NO-induced apoptosis resulted in uncontrolled cytokine production, rather than a biased Th2 cytokine pattern. Together, these results suggested that Fas and FasL-induced apoptosis could be implied in modulation of the immune response against T. cruzi by interfering with cytokine and NO production during the acute phase of the infection.

Chagas' disease can lead to severe and potentially lethal damage of cardiac function. Thus, the identification of contractile abnormalities in asymptomatic patients can be important for risk stratification in those patients. Doppler tissue imaging (DTI) is a new diagnostic modality for the study of regional and longitudinal contractility of the left ventricle. However, DTI has not been used for the assessment of Chagas' cardiopathy. The purpose of this study was to identify abnormalities related to longitudinal contractility by means of DTI in patients with an undetermined form of Chagas' disease and with normal echocardiogram and Doppler studies. Forty patients were studied, including 21 chagasic ones with normal electrocardiographic, radiologic, and echocardiographic studies, and 19 normal control individuals. All of the patients were submitted to DTI to evaluate longitudinal contractility in the various myocardial segments, including assessment of systolic and diastolic velocities and isovolumic contraction time (IVCT). Similar values were observed among the various systolic function rates in both groups, except for the IVCT along the septal wall, which was significantly higher in the chagasic group. DTI enabled the early detection of contractile abnormalities in patients with an undetermined form of Chagas' disease and with normal echocardiogram. Such abnormalities were particularly striking in the interventricular septum. The present study could be useful in risk stratification for those patients.