Increased type 1 chemokine expression in experimental Chagas disease correlates with cardiac pathology in beagle dogs

Trypanosoma cruzi infection increases atherosclerotic lesion in ApoE-deficient mice

Apolipoprotein E (ApoE) is the major ligand for the transporting and removal of chylomicrons and lipoproteins by the liver. Since the creation of the ApoE-knockout mice, it is well established that ApoE deficiency results in spontaneous atherosclerosis in aged animals. Atherosclerosis is also observed in animals infected with Trypanosoma cruzi, a protozoan that elicits a systemic inflammatory response in mammalian hosts, culminating in damage to cardiac, neuronal, and endothelial cells. Pro-atherogenic effects related to the experimental infection with T. cruzi may be induced by inflammatory components affecting the vascular wall. Herein, we evaluated whether infection with different strains of T. cruzi worsened the atherogenic lesions observed in aged ApoE^-/- mice. After four weeks of infection with Berenice-78 (Be-78) or Colombian (Col) strains of the parasite, mice presented increased CCL2 and CCL5 production and high migration of inflammatory cells to cardiac tissue. Although the infection with either strain did not affect the survival rate, only the infection with Col strain caused abundant parasite growth in blood and heart and increased aortic root lesions in ApoE^-/- mice. Our findings show, for the first time that ApoE exerts a protective anti-atherosclerotic role in the aortic root of mice in the acute phase of experimental infection with the Col strain of T. cruzi. Further studies should target ApoE and nutritional interventions to modulate susceptibility to cardiovascular disabilities after T. cruzi infection, minimizing the risk of death in both experimental animals and humans.

In vitro tripanocidal effect of 1,8-dioxooctahydroxanthenes (xanthenodiones) and tetraketones and improvement of cardiac parameters in vivo

OBJECTIVE

Trypanosoma cruzi infection affects millions of people worldwide, and the drugs available for its treatment have limited efficacy. 1,8-Dioxooctahydroxanthenes and tetraketones are compounds with important biological applications. The aim of this study was to assess the trypanocidal and inflammatory activities of nine 1,8-dioxooctahydroxanthenes (1-9) and three tetraketones (10-12).

METHODS AND RESULTS

By in vitro killing assay, three compounds were able to eliminate CL TdTomato expressing strain of T. cruzi, 9 (IC₅₀=30.65μM), 10 (IC₅₀=14.11μM), and 11 (IC₅₀=26.43μM). However, only 9 was not toxic to Vero cells. Next, to evaluate the in vivo antitrypanosomal and immunological efficacy of 9, Swiss mice were infected with the Y and CL strains of T. cruzi and treated for 10 days with 50mg/kg of 9. This compound reduced the cardiac inflammatory infiltration in animals infected with both strains. Rank's ligand (RankL), CCL2, and interferon (IFN)-γ were measured in the cardiac tissue homogenate of the Y-strain-infected animals, and no interference of 9 was observed. However, compound 9 increased the RankL and interleukin (IL)-10 levels in CL-infected mice. No hepatic and renal toxicity was observed.

CONCLUSION

Our findings showed that 1,8-dioxooctahydroxanthene has antiparasitic effect and ameliorates the cardiac inflammatory parameters related to T. cruzi infection.

Visceral leishmaniasis: a practical strategy for quantitative molecular diagnosis in naturally infected dogs

The diagnosis of canine visceral leishmaniasis (CVL) has been a problem for public health services due to the variety of clinical signs similar to other diseases and low sensitivity and specificity of available tests. In this sense, our main objective was to develop a simple, rapid, and accurate quantitative real-time PCR (qPCR) diagnosis for CVL. Thus, low-invasive samples from bone marrow (BM), popliteal lymph nodes (PLN), and conjunctival swabs (CS) were selected from negative and VL-positive dogs, using as gold standard, immunological and parasitological tests performed with different tissues. Oligonucleotides for Leishmania infantum kDNA were designed and the limit of quantification and amplification efficiency of the qPCR were determined using tissue-specific standards produced with DNA from those different tissues, mixed with DNA from a known amount of L. infantum promastigotes. Endogenous control was used to validate a comparative Ct method, and tissue parasite concentrations were estimated by comparison with tissue-specific reference standard samples. The overall analysis of the qPCR data suggests the following ranking for tissue choice: PLN > BM > CS. Finally, we have concluded that this molecular approach simplifies and accelerates the quantitative diagnostic process because it is easy to perform, requiring no DNA dosing or standard curve application, and it shows good diagnostic parameters, especially when using popliteal lymph node samples.

Benznidazole, itraconazole and their combination in the treatment of acute experimental chagas disease in dogs

Chagas disease (CD) is a serious public health problem in Latin America and its treatment remains neglected. Benznidazole (BZ), the only drug available in Brazil, presents serious side effects and low therapeutic efficacy, especially at the chronic phase. The last clinical trials demonstrated that the first generation of azole compounds were less successful than BZ in CD chemotherapy, which stimulated studies of these compounds associated to BZ and nifurtimox (NF). This study evaluated the therapeutic efficacy of BZ, itraconazole (ITZ) and their combination (BZ + ITZ) in dogs infected with the VL-10 T. cruzi strain in the acute phase of the disease. Twenty young mongrel dogs were inoculated with 2.0 × 10³ blood trypomastigotes/kg and divided into four groups: treated with BZ, ITZ and BZ + ITZ for 60 days, and control group (INT). The parasitemia of the BZ + ITZ and BZ groups were similar and showed significant reduction compared to the INT group. The group treated with ITZ also showed significant parasitemia reduction compared to the INT group. The global analysis of hemoculture (HC), blood PCR, conventional serology (CS-ELISA), heart qPCR and histopathology techniques, used in the post-treatment evaluation, revealed that BZ + ITZ combination lead to a more reduction of parasitemia during the acute phase and heart qPCR positivity, less cardiac damage (inflammation and fibrosis in the left ventricle) and total survival. According to the classical cure criteria one animal treated with BZ + ITZ can be considered cured in its final evaluation and two other dogs, one of this group and one treated with ITZ were in process of cure. At least for BZ-resistant T. cruzi strains such as VL-10, BZ + ITZ was not effective to induce parasitological cure or a profound and sustained reduction of the parasite burden in blood and infected organs.

CD43 sialoglycoprotein modulates cardiac inflammation and murine susceptibility to Trypanosoma cruzi infection

CD43 (leukosialin) is a large sialoglycoprotein abundantly expressed on the surface of most cells from the hematopoietic lineage. CD43 is directly involved in the contact between cells participating in a series of events such as signaling, adherence and host parasite interactions. In this study we examined the role of CD43 in the immune response against Trypanosoma cruzi, the protozoan parasite that causes Chagas’ disease, a potential life-threatening illness endemic in 21 Latin American countries according to the WHO. The acute stage of infection is marked by intense parasitemia and cardiac tissue parasitism, resulting in the recruitment of inflammatory cells and acute damage to the heart tissue. We show here that CD43^−/− mice were more resistant to infection due to increased cytotoxicity of antigen specific CD8+ T cells and reduced inflammatory infiltration in the cardiac tissue, both contributing to lower cardiomyocyte damage. In addition, we demonstrate that the induction of acute myocarditis involves the engagement of CD43 cytoplasmic tripeptide sequence KRR to ezrin-radixin-moiesin cytoskeletal proteins. Together, our results show the participation of CD43 in different events involved in the pathogenesis of T. cruzi infection, contributing to a better overall understanding of the mechanisms underlying the pathogenesis of acute chagasic cardiomyopathy.

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

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

Canine Macrophage DH82 Cell Line As a Model to Study Susceptibility to Trypanosoma cruzi Infection

Trypanosoma cruzi is an obligatory intracellular protozoan parasite, and it is the etiological agent of Chagas' disease that is endemic in the Americas. In addition to humans, a wide spectrum of mammals can be infected by T. cruzi, including dogs. Dogs develop acute and chronic disease, similar to human infection. T. cruzi can infect almost all cell types and after cell invasion, the metacyclics trypomastigotes localize in the cytoplasm, where they transform into amastigotes, the replicative form of T. cruzi in mammals. After amastigote multiplication and differentiation, parasites lyse host cells and spread through the body by blood circulation. In this work, we evaluated the in vitro ability of T. cruzi to infect a canine macrophage cell line DH82 compared with RAW264.7, a murine tissue culture macrophage. Our results have shown that the T. cruzi is able to infect, replicate and differentiate in DH82 cell line. We observed that following treatment with LPS and IFN-γ DH82 cells were more resistant to infection and that resistance was not related reactive oxygen species production in our system. In this study, we also found that DH82 cells became more susceptible to T. cruzi infection when cocultured with apoptotic cells. The analysis of cytokine production has showed elevated levels of the TGF-β, IL-10, and TNF-α produced by T. cruzi-infected canine macrophages. Additionally, we demonstrated a reduced expression of the MHC class II and CD80 by infected DH82 cell line.

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

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

Plasma concentrations of CCL3 and CCL4 in the cardiac and digestive clinical forms of chronic Chagas disease

The aim of this study was to investigate the plasma levels of the CCL3 and CCL4 chemokines in patients with the cardiac and digestive clinical forms of chronic Chagas disease and in cardiac patients with and without left ventricular systolic dysfunction (LVSD). Plasma samples from 75 patients were evaluated by enzyme-linked immunosorbent assay (ELISA) to confirm infection by T. cruzi. Plasma levels of the CCL3 and CCL4 chemokines were measured using Milliplex® MAP assay (Millipore). There were no significant differences in the levels of CCL3 and CCL4 between patients with the digestive and cardiac clinical forms of Chagas disease. Moreover, no significant differences were found between patients without LVSD and those with LVSD. Higher CCL3 and CCL4 plasma levels were found in patients with LVSD compared to those with the digestive form of the disease. The CCL3 and CCL4 chemokines might not be involved in differential susceptibility to the digestive and cardiac clinical forms of chronic Chagas disease, and it seems they do not influence the development of LVSD.

Expression and production of cardiac angiogenic mediators depend on the Trypanosoma cruzi-genetic population in experimental C57BL/6 mice infection

Mammalian cardiac cells are important targets to the protozoan Trypanosoma cruzi. The inflammatory reaction in the host aims at eliminating this parasite, can lead to cell destruction, fibrosis and hypoxia. Local hypoxia is well-defined stimulus to the production of angiogenesis mediators. Assuming that different genetic T. cruzi populations induce distinct inflammation and disease patterns, the current study aims to investigate whether the production of inflammatory and angiogenic mediators is a parasite strain-dependent condition. C57BL/6 mice were infected with the Y and Colombian strains of T. cruzi and euthanized at the 12th and 32nd days, respectively. The blood and heart tissue were processed in immune assays and/or qPCR (TNF, IL-17, IL-10, CCL2, CCL3, CCL5, CCR2, CCR5 and angiogenic factors VEGF, Ang-1, Ang-2) and in histological assays. The T. cruzi increased the inflammatory and angiogenic mediators in the infected mice when they were compared to non-infected animals. However, the Colombian strain has led to higher (i) leukocyte infiltration, (ii) cardiac TNF and CCL5 production/expression, (iii) cardiac tissue parasitism, and to higher (iv) ratio between heart/body weights. On the other hand, the Colombian strain has caused lower production and expression VEGF, Ang-1 and Ang-2, when it was compared to the Y strain of the parasite. The present study highlights that the T. cruzi-genetic population defines the pattern of angiogenic/inflammatory mediators in the heart tissue, and that it may contribute to the magnitude of the cardiac pathogenesis. Besides, such assumption opens windows to the understanding of the angiogenic mediator's role in association with the experimental T. cruzi infection.

Doxycycline and Benznidazole Reduce the Profile of Th1, Th2, and Th17 Chemokines and Chemokine Receptors in Cardiac Tissue from Chronic Trypanosoma cruzi-Infected Dogs

Chemokines (CKs) and chemokine receptors (CKR) promote leukocyte recruitment into cardiac tissue infected by the Trypanosoma cruzi. This study investigated the long-term treatment with subantimicrobial doses of doxycycline (Dox) in association, or not, with benznidazole (Bz) on the expression of CK and CKR in cardiac tissue. Thirty mongrel dogs were infected, or not, with the Berenice-78 strain of T. cruzi and grouped according their treatments: (i) two months after infection, Dox (50 mg/kg) 2x/day for 12 months; (ii) nine months after infection, Bz (3,5 mg/kg) 2x/day for 60 days; (iii) Dox + Bz; and (iv) vehicle. After 14 months of infection, hearts were excised and processed for qPCR analysis of Th1 (CCL2, CCL3, CCL4, CCL5, CXCL9, and CXCL11), Th2 (CCL1, CCL17, CCL24, and CCL26), Th17 (CCL20) CKs, Th1 (CCR5, CCR6, and CXCR3), and Th2/Th17 (CCR3, CCR4, and CCR8) CKR, as well as IL-17. T. cruzi infection increases CCL1, CCL2, CCL4, CCL5, CCL17, CXCL10, and CCR5 expression in the heart. Dox, Bz, or Dox + Bz treatments cause a reversal of CK and CKR and reduce the expression of CCL20, IL-17, CCR6, and CXCR3. Our data reveal an immune modulatory effect of Dox with Bz, during the chronic phase of infection suggesting a promising therapy for cardiac protection.

Chagas cardiomyopathy: The potential effect of benznidazole treatment on diastolic dysfunction and cardiac damage in dogs chronically infected with Trypanosoma cruzi

Cardiac involvement represents the main cause of mortality among patients with Chagas disease, and the relevance of trypanocidal treatment to improving diastolic dysfunction is still doubtful. In the present study, we used a canine model infected with the benznidazole-sensitive Berenice-78 Trypanosoma cruzi strain to verify the efficacy of an etiologic treatment in reducing the parasite load and ameliorating cardiac muscle tissue damage and left ventricular diastolic dysfunction in the chronic phase of the infection. The effect of the treatment on reducing the parasite load was monitored by blood PCR and blood culture assays, and the effect of the treatment on the outcome of heart tissue damage and on diastolic function was evaluated by histopathology and echo Doppler cardiogram. The benefit of the benznidazole-treatment in reducing the parasite burden was demonstrated by a marked decrease in positive blood culture and PCR assay results until 30days post-treatment. At this time, the PCR and blood culture assays yielded negative results for 82% of the treated animals, compared with only 36% of the untreated dogs. However, a progressive increase in the parasite load could be detected in the peripheral blood for one year post-treatment, as evidenced by a progressive increase in positive results for both the PCR and the blood culture assays at follow-up. The parasite load reduction induced by treatment was compatible with the lower degree of tissue damage among animals euthanized in the first month after treatment and with the increased cardiac damage after this period, reaching levels similar to those in untreated animals at the one-year follow-up. The two infected groups also presented similar, significantly smaller values for early tissue septal velocity (E' SIV) than the non-infected dogs did at this later time. Moreover, in the treated animals, an increase in the E/E' septal tissue filling pressure ratio was observed when compared with basal values as well as with values in non-infected dogs. These findings strongly suggest that the temporary reduction in the parasite load that was induced by benznidazole treatment was not able to prevent myocardial lesions and diastolic dysfunction for long after treatment.

The role of CCR5 in Chagas disease - a systematic review

Chagas disease is an infection caused by the protozoan Trypanosoma cruzi. The clinical manifestations result from the chronic forms of the disease: indeterminate, cardiac, digestive or mixed. The pathogenesis of this disease is related to the genetic variability of both the parasite and the host with polymorphisms of genes involved in immune response possibly being involved in the variable clinical course. Cytokines play a key role in regulating immune response, in particular chemokines exert a crucial role in the control of leukocyte migration during the host's response to infectious processes. Furthermore, inflammatory cytokines and chemokines have been implicated in the generation of inflammatory infiltrates and tissue damage. The involvement of the CC Chemokine Receptor 5 (CCR5) in leukocyte migration to sites of inflammation has been elucidated and this receptor has been investigated in Chagas disease. Here we review the role of CCR5 in T. cruzi infection as well as its importance in the pathogenesis of the Chagas disease.

Domestic Pig (Sus scrofa) as an Animal Model for Experimental Trypanosoma cruzi Infection

Pigs were infected with a Bolivian strain of Trypanosoma cruzi (genotype I) and evaluated up to 150 days postinoculation (dpi) to determine the use of pigs as an animal model of Chagas disease. Parasitemia was observed in the infected pigs during the acute phase (15-40 dpi). Anti-T. cruzi immunoglobulin M was detected during 15-75 dpi; high levels of anti-T. cruzi immunoglobulin G were detected in all infected pigs from 75 to 150 dpi. Parasitic DNA was observed by western blot (58%, 28/48) and polymerase chain reaction (27%, 13/48) in urine samples, and in the brain (75%, 3/4), spleen (50%, 2/4), and duodenum (25%, 1/4), but no parasitic DNA was found in the heart, colon, and kidney. Parasites were not observed microscopically in tissues samples, but mild inflammation, vasculitis, and congestion was observed in heart, brain, kidney, and spleen. This pig model was useful for the standardization of the urine test because of the higher volume that can be obtained as compared with other small animal models. However, further experiments are required to observe pathological changes characteristic of Chagas disease in humans.

Emerging importance of chemokine receptor CXCR3 and its ligands in cardiovascular diseases

The CXC chemokines, CXCL4, -9, -10, -11, CXCL4L1, and the CC chemokine CCL21, activate CXC chemokine receptor 3 (CXCR3), a cell-surface G protein-coupled receptor expressed mainly by Th1 cells, cytotoxic T (Tc) cells and NK cells that have a key role in immunity and inflammation. However, CXCR3 is also expressed by vascular smooth muscle and endothelial cells, and appears to be important in controlling physiological vascular function. In the last decade, evidence from pre-clinical and clinical studies has revealed the participation of CXCR3 and its ligands in multiple cardiovascular diseases (CVDs) of different aetiologies including atherosclerosis, hypertension, cardiac hypertrophy and heart failure, as well as in heart transplant rejection and transplant coronary artery disease (CAD). CXCR3 ligands have also proven to be valid biomarkers for the development of heart failure and left ventricular dysfunction, suggesting an underlining pathophysiological relation between levels of these chemokines and the development of adverse cardiac remodelling. The observation that several of the above-mentioned chemokines exert biological actions independent of CXCR3 provides both opportunities and challenges for developing effective drug strategies. In this review, we provide evidence to support our contention that CXCR3 and its ligands actively participate in the development and progression of CVDs, and may additionally have utility as diagnostic and prognostic biomarkers.

Genetic Susceptibility to Cardiac and Digestive Clinical Forms of Chronic Chagas Disease: Involvement of the CCR5 59029 A/G Polymorphism

The clinical manifestations of chronic Chagas disease include the cardiac form of the disease and the digestive form. Not all the factors that act in the variable clinical course of this disease are known. This study investigated whether the CCR5Δ32 (rs333) and CCR5 59029 A/G (promoter region--rs1799987) polymorphisms of the CCR5 gene are associated with different clinical forms of chronic Chagas disease and with the severity of left ventricular systolic dysfunction in patients with chronic Chagas heart disease (CCHD). The antibodies anti-T. cruzi were identified by ELISA. PCR and PCR-RFLP were used to identify the CCR5Δ32 and CCR5 59029 A/G polymorphisms. The chi-square test was used to compare variables between groups. There was a higher frequency of the AA genotype in patients with CCHD compared with patients with the digestive form of the disease and the control group. The results also showed a high frequency of the AG genotype in patients with the digestive form of the disease compared to the other groups. The results of this study show that the CCR5Δ32 polymorphism does not seem to influence the different clinical manifestations of Chagas disease but there is involvement of the CCR5 59029 A/G polymorphism in susceptibility to the different forms of chronic Chagas disease. Besides, these polymorphisms do not influence left ventricular systolic dysfunction in patients with CCHD.

Interferon-γ and other inflammatory mediators in cardiomyocyte signaling during Chagas disease cardiomyopathy

Chagas disease cardiomyopathy (CCC), the main consequence of Trypanosoma cruzi (T.cruzi) infection, is an inflammatory cardiomyopathy that develops in up to 30% of infected individuals. The heart inflammation in CCC patients is characterized by a Th1 T cell-rich myocarditis with increased production of interferon (IFN)-γ, produced by the CCC myocardial infiltrate and detected at high levels in the periphery. IFN-γ has a central role in the cardiomyocyte signaling during both acute and chronic phases of T.cruzi infection. In this review, we have chosen to focus in its pleiotropic mode of action during CCC, which may ultimately be the strongest driver towards pathological remodeling and heart failure. We describe here the antiparasitic protective and pathogenic dual role of IFN-γ in Chagas disease.

Chagas disease cardiomyopathy: immunopathology and genetics

Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and affects ca. 10 million people worldwide. About 30% of Chagas disease patients develop chronic Chagas disease cardiomyopathy (CCC), a particularly lethal inflammatory cardiomyopathy that occurs decades after the initial infection, while most patients remain asymptomatic. Mortality rate is higher than that of noninflammatory cardiomyopathy. CCC heart lesions present a Th1 T-cell-rich myocarditis, with cardiomyocyte hypertrophy and prominent fibrosis. Data suggest that the myocarditis plays a major pathogenetic role in disease progression. Major unmet goals include the thorough understanding of disease pathogenesis and therapeutic targets and identification of prognostic genetic factors. Chagas disease thus remains a neglected disease, with no vaccines or antiparasitic drugs proven efficient in chronically infected adults, when most patients are diagnosed. Both familial aggregation of CCC cases and the fact that only 30% of infected patients develop CCC suggest there might be a genetic component to disease susceptibility. Moreover, previous case-control studies have identified some genes associated to human susceptibility to CCC. In this paper, we will review the immunopathogenesis and genetics of Chagas disease, highlighting studies that shed light on the differential progression of Chagas disease patients to CCC.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Myocardial chemokine expression and intensity of myocarditis in Chagas cardiomyopathy are controlled by polymorphisms in CXCL9 and CXCL10

Background

Chronic Chagas cardiomyopathy (CCC), a life-threatening inflammatory dilated cardiomyopathy, affects 30% of the approximately 8 million patients infected by Trypanosoma cruzi. Even though the Th1 T cell-rich myocarditis plays a pivotal role in CCC pathogenesis, little is known about the factors controlling inflammatory cell migration to CCC myocardium.

Methods and Results

Using confocal immunofluorescence and quantitative PCR, we studied cell surface staining and gene expression of the CXCR3, CCR4, CCR5, CCR7, CCR8 receptors and their chemokine ligands in myocardial samples from end-stage CCC patients. CCR5+, CXCR3+, CCR4+, CCL5+ and CXCL9+ mononuclear cells were observed in CCC myocardium. mRNA expression of the chemokines CCL5, CXCL9, CXCL10, CCL17, CCL19 and their receptors was upregulated in CCC myocardium. CXCL9 mRNA expression directly correlated with the intensity of myocarditis, as well as with mRNA expression of CXCR3, CCR4, CCR5, CCR7, CCR8 and their ligands. We also analyzed single-nucleotide polymorphisms for genes encoding the most highly expressed chemokines and receptors in a cohort of Chagas disease patients. CCC patients with ventricular dysfunction displayed reduced genotypic frequencies of CXCL9 rs10336 CC, CXCL10 rs3921 GG, and increased CCR5 rs1799988CC as compared to those without dysfunction. Significantly, myocardial samples from CCC patients carrying the CXCL9/CXCL10 genotypes associated to a lower risk displayed a 2–6 fold reduction in mRNA expression of CXCL9, CXCL10, and other chemokines and receptors, along with reduced intensity of myocarditis, as compared to those with other CXCL9/CXCL10 genotypes.

Conclusions

Results may indicate that genotypes associated to reduced risk in closely linked CXCL9 and CXCL10 genes may modulate local expression of the chemokines themselves, and simultaneously affect myocardial expression of other key chemokines as well as intensity of myocarditis. Taken together our results may suggest that CXCL9 and CXCL10 are master regulators of myocardial inflammatory cell migration, perhaps affecting clinical progression to the life-threatening form of CCC.

Chronic Chagas cardiomyopathy (CCC) is an inflammatory heart disease that affects millions in Latin America, and in growing numbers in USA and Europe. Survival among CCC patients is shorter than among patients with cardiomyopathy of non-inflammatory etiology. This suggests that the inflammatory cell influx plays an important pathogenic role in CCC. However, little is known about the factors that maintain this myocardial inflammation. We hypothesized that Th1 T cell-attracting chemokines, involved in driving leukocyte migration, could play a role in myocardial inflammation. Herein, we have analyzed expression of several chemokines and receptors in heart tissue from patients with CCC and controls. We found inflammatory cells expressing chemokines and receptors consistent with Th1 T cell influx into CCC myocardium. mRNA expression levels of the chemokine CXCL9 correlated with inflammation. We also studied whether genetic variations in these genes could be associated to CCC development. Polymorphisms in CXCL9, CXCL10 and CCR5 were associated to differential risk of progression to the more severe form of CCC. Polymorphisms of CXCL9 and CXCL10 were also associated to the intensity of myocardial inflammation and chemokine expression. These results suggest that such chemokines may be master regulators of myocardial inflammatory cell migration, perhaps affecting clinical progression to severe CCC.

Modulation of paraoxonases during infectious diseases and its potential impact on atherosclerosis

The paraoxonase (PON) gene family includes three members, PON1, PON2 and PON3, aligned in tandem on chromosome 7 in humans and on chromosome 6 in mice. All PON proteins share considerable structural homology and have the capacity to protect cells from oxidative stress; therefore, they have been implicated in the pathogenesis of several inflammatory diseases, particularly atherosclerosis. The major goal of this review is to highlight the modulation of each of the PONs by infective (bacterial, viral and parasitic) agents, which may shed a light on the interaction between infectious diseases and PONs activities in order to effectively reduce the risk of developing atherosclerosis.

Pathogenesis of Chagas disease cardiomyopathy

Chagas disease, or American trypanosomiasis, is a parasitic infection caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is mainly affecting rural populations in Mexico and Central and South America. The World Health Organization estimates that 300 000 new cases of Chagas disease occur every year and approximately 20 000 deaths are attributable to Chagas. However, this organisation classified Chagas disease as a neglected tropical disease. The economic burden of this disease is significant. In many Latin American countries, the direct and indirect costs, including the cost of health care in dollars and loss of productivity, attributable to Chagas disease ranges from $40 million to in excess of $800 million per nation per annum. So, it remains a contemporary public health concern. In chronic phase, mortality is primarily due to the rhythm disturbances and congestive heart failure that result from the chronic inflammatory cardiomyopathy (CCC) due to the persistence presence of parasites in the heart tissue. Mechanisms underlying differential progression to CCC are still incompletely understood. In the last decades immunological proteomic genetic approaches lead to significant results which help to disperse the veil covering the knowledge of the pathogenic process. Here, we reported these significant progresses.

Hematological alterations during experimental canine infection by Trypanosoma cruzi

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

Genetic variants in the chemokines and chemokine receptors in Chagas disease

Clinical symptoms of Chagas' disease occur in 30% of the individuals infected with Trypanosoma cruzi and are characterised by heart inflammation and dysfunction. Chemokines and chemokine receptors control the migration of leukocytes during the inflammatory process and are involved in the modulation of Th1 or Th2 responses. To determine their influence, we investigated the possible role of CCL5/RANTES and CXCL8/IL8 chemokines, and CCR2 and CCR5 chemokines receptors cluster gene polymorphisms with the development of chagasic cardiomyopathy. Our study included 260 Chagas seropositive individuals (asymptomatic, n=130; cardiomyopathic, n=130) from an endemic area of Colombia. Genotyping was performed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and TaqMan SNP genotyping assay. We found statistically significant differences in the distribution of the CCR5 human haplogroup (HH)-A (p=0.027; OR=3.78, 95% CI=1.04-13.72). Moreover, we found that the CCR5-2733 G and CCR5-2554 T alleles are associated, respectively, with a reduced risk of susceptibility and severity to develop chagasic cardiomyopathy. No other associations were found to be significant for the other polymorphisms analysed in the CCR5, CCR2, CCL5/RANTES and CXCL8/IL8 genes. Our data suggest that the analysed chemokines and chemokine receptor genetic variants have a weak but important association with the development of chagasic cardiomyopathy in the population under study.

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

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

Inflammation and Chagas disease some mechanisms and relevance

Chagas cardiomyopathy is caused by infection with flagellated protozoan Trypanosoma cruzi. In patients, there is a fine balance between control of the replication and the intensity of the inflammatory response so that the host is unable to eliminate the parasite resulting in the parasite persisting as a lifelong infection in most individuals. However, the parasite persists in such a way that it causes no or little disease. This chapter reviews our understanding of many of the mediators of inflammation and cells which are involved in the inflammatory response of mammals to T. cruzi infection. Particular emphasis is given to the role of chemokines, endothelin and lipid mediators. Understanding the full range of mediators and cells present and how they interact with each other in Chagas disease may shed light on how we modulate disease pathogenesis and define new approaches to treat or prevent the disease.