Does orchiectomy enhance the immune-stimulatory effects of melatonin during experimental Chagas' disease?

Melatonin has been reported to play a fundamental role in T-cell immunoregulation. Control of Trypanosome cruzi parasitism during the acute phase of infection is considered to be critically dependent on direct macrophage activation by cytokines. The aim of this work was to evaluate the influence of exogenous melatonin treatment and the influences exerted by sexual hormones during the acute phase of the experimental Chagas' disease in rats. With melatonin treatment, orchiectomized animals (CMOR and IMOR) displayed the highest concentrations of IFN-gamma and TNF-alpha. On the 7th day post-infection, untreated and treated orchiectomized animals (IOR and IMOR) showed an enhanced number of peritoneal macrophages. Nitric oxide levels were also increased in untreated and treated orchiectomized (IOR and IMOR) when compared to the other groups, with or without LPS. Our data suggest that melatonin therapy associated with orchiectomy induced a stimulating effect on the immune response to the parasite. (c) 2012 Published by Elsevier Ltd.

EFFECTS OF VITAMIN C SUPPLEMENTATION ON ACUTE PHASE CHAGAS DISEASE IN EXPERIMENTALLY INFECTED MICE WITH Trypanosoma cruzi QM1 STRAIN

The tissue changes that occur in Chagas disease are related to the degree of oxidative stress and antioxidant capacity of affected tissue. Studies with vitamin C supplementation did not develop oxidative damage caused by Chagas disease in the host, but other studies cite the use of peroxiredoxins ascorbate - dependent on T. cruzi to offer protection against immune reaction. Based on these propositions, thirty "Swiss" mice were infected with T. cruzi QM1 strain and treated with two different vitamin C doses in order to study the parasitemia evolution, histopathological changes and lipid peroxidation biomarkers during the acute phase of Chagas disease. The results showed that the parasite clearance was greater in animals fed with vitamin C overdose. There were no significant differences regarding the biomarkers of lipid peroxidation and inflammatory process or the increase of myocardium in animals treated with the recommended dosage. The largest amount of parasite growth towards the end of the acute phase suggests the benefit of high doses of vitamin C for trypomastigotes. The supplementation doesn't influence the production of free radicals or the number of amastigote nests in the acute phase of Chagas disease.

A General Latent Class Model for Performance Evaluation of Diagnostic Tests in the Absence of a Gold Standard: An Application to Chagas Disease

We propose a new general Bayesian latent class model for evaluation of the performance of multiple diagnostic tests in situations in which no gold standard test exists based on a computationally intensive approach. The modeling represents an interesting and suitable alternative to models with complex structures that involve the general case of several conditionally independent diagnostic tests, covariates, and strata with different disease prevalences. The technique of stratifying the population according to different disease prevalence rates does not add further marked complexity to the modeling, but it makes the model more flexible and interpretable. To illustrate the general model proposed, we evaluate the performance of six diagnostic screening tests for Chagas disease considering some epidemiological variables. Serology at the time of donation (negative, positive, inconclusive) was considered as a factor of stratification in the model. The general model with stratification of the population performed better in comparison with its concurrents without stratification. The group formed by the testing laboratory Biomanguinhos FIOCRUZ-kit (c-ELISA and rec-ELISA) is the best option in the confirmation process by presenting false-negative rate of 0.0002% from the serial scheme. We are 100% sure that the donor is healthy when these two tests have negative results and he is chagasic when they have positive results.

Antiparasitical chemotherapy in Chagas' disease cardiomyopathy: current evidence

Chronic chagasic cardiomyopathy affects 20% of Chagas disease patients. At present, Chagas disease chemotherapy uses nitrofurans, benznidazole (Rochagan (R), Rodanil (R), Roche) or nifurtimox (Lampit (R), Bayer). Treatment during acute and recent chronic phases in childhood effects 71.5% and 57.6%, respectively, of parasitological cure. However, in clinical trials during the late chronic phase, only 5.9% of parasitological cure were achieved. This review focuses on the benefit from aetiological treatment to avoid, stop or revert myocarditis. Divergent data gathered from clinical practice are not convincing to support prescription of aetiological treatment as routine for indeterminate and cardiac chronic patients.

Effect of Colchicine on Myocardial Injury Induced by Trypanosoma cruzi in Experimental Chagas Disease

Background: The hallmark of Chagas disease (CD) is multifocal myocarditis and extensive fibrosis. We investigated the potential effect of colchicine on myocardial remodeling in experimental CD. Methods and Results: One hundred Syrian hamsters were randomly divided into noninfected untreated control (CG), noninfected control treated with colchicine (COLG 0.4 mg kg(-1) d(-1) by gavage), infected (IG), and infected treated with colchicine (ICOLG, 0.4 mg kg(-1) d(-1)) groups. The interstitial collagen volume fraction (ICVF) was evaluated by videomorphometry with picrosirius red staining. The gelatinolytic activities of matrix metalloproteinase (MMP) 2 were examined with the use of zymography. Myocarditis was described according to the Dallas criteria. Statistical comparisons were performed with parametric analysis of variance and Tukey test. ICVF (%) accumulation was attenuated in infected colchicine-treated animals in the left (CG 0.81 +/- 0.13, COLG 0.85 +/- 0.13, IG: 1.35 +/- 0.31,* ICOLG 1.06 +/- 0.19; *P < .05 compared with ICOLG) and right ventricles (CG 1.4 +/- 0.36, COLG 1.26 +/- 0.14, IG 1.97 +/- 0.058,* ICOLG: 1.52 +/- 0.23; *P < .05 compared with ICOLG). A significant increase in MMP-2 enzymatic activity (UA) was observed in ICOLG (17,432.8*) compared with GC (3731.6), COLG (2,792.6), and IG (4,286.3; *P < .001). In IG, 66% of animals had myocarditis compared with only 49% in ICOLG. Conclusions: Colchicine had a protective effect on myocardium, indicated by decreased interstitial myocardial fibrosis, increased intensity of MMP-2, and attenuated myocardial inflammation. (J Cardiac Fail 2012;18:654-659)

Congenital Chagas disease: time to screen pregnant women?

The congenital transmission of Trypanosoma cruzi has gained epidemiological importance because it is partially responsible for the spread of Chagas disease worldwide. The feasibility of a cure when infected children are treated early makes the detection of congenital infection a valuable goal toward the control of the disease. Here, the authors review and discuss the findings of Bua et al., who quantified the parasitemia of infected women and their newborns by quantitative PCR. The authors demonstrate that the maternal parasite burden is directly related to the risk of neonatal infection. This study points out the importance of a quantitative screen for T. cruzi in pregnant women who live in, or have traveled to, endemic areas for improving the diagnosis of infected newborns and providing prompt treatment.

Oral Transmission of Chagas Disease

Chagas disease is now an active disease in the urban centers of countries of nonendemicity and endemicity because of congenital and blood and/or organ transplantation transmissions and the reactivation of the chronic disease in smaller scale than vectorial transmission, reported as controlled in countries of endemicity. Oral transmission of Chagas disease has emerged in unpredictable situations in the Amazon region and, more rarely, in areas of nonendemicity where the domiciliary triatomine cycle was under control because of exposition of the food to infected triatomine and contaminated secretions of reservoir hosts. Oral transmission of Chagas disease is considered when >1 acute case of febrile disease without other causes is linked to a suspected food and should be confirmed by the presence of the parasite after direct microscopic examination of the blood or other biological fluid sample from the patient.

Deficient Regulatory T Cell Activity and Low Frequency of IL-17-Producing T Cells Correlate with the Extent of Cardiomyopathy in Human Chagas' Disease

Background: Myocardium damage during Chagas' disease results from the immunological imbalance between pro-and production of anti-inflammatory cytokines and has been explained based on the Th1-Th2 dichotomy and regulatory T cell activity. Recently, we demonstrated that IL-17 produced during experimental T. cruzi infection regulates Th1 cells differentiation and parasite induced myocarditis. Here, we investigated the role of IL-17 and regulatory T cell during human Chagas' disease. Methodology/Principal Findings: First, we observed CD4(+)IL-17(+) T cells in culture of peripheral blood mononuclear cells (PBMC) from Chagas' disease patients and we evaluated Th1, Th2, Th17 cytokine profile production in the PBMC cells from Chagas' disease patients (cardiomyopathy-free, and with mild, moderate or severe cardiomyopathy) cultured with T. cruzi antigen. Cultures of PBMC from patients with moderate and severe cardiomyopathy produced high levels of TNF-alpha, IFN-gamma and low levels of IL-10, when compared to mild cardiomyopathy or cardiomyopathy-free patients. Flow cytometry analysis showed higher CD4(+)IL-17(+) cells in PBMC cultured from patients without or with mild cardiomyopathy, in comparison to patients with moderate or severe cardiomyopathy. We then analyzed the presence and function of regulatory T cells in all patients. All groups of Chagas' disease patients presented the same frequency of CD4(+)CD25(+) regulatory T cells. However, CD4(+)CD25(+) T cells from patients with mild cardiomyopathy or cardiomyopathy-free showed higher suppressive activity than those with moderate and severe cardiomyopathy. IFN-gamma levels during chronic Chagas' disease are inversely correlated to the LVEF (P = 0.007, r = -0.614), while regulatory T cell activity is directly correlated with LVEF (P = 0.022, r = 0.500). Conclusion/Significance: These results indicate that reduced production of the cytokines IL-10 and IL-17 in association with high levels of IFN-gamma and TNF-alpha is correlated with the severity of the Chagas' disease cardiomyopathy, and the immunological imbalance observed may be causally related with deficient suppressor activity of regulatory T cells that controls myocardial inflammation.

Highlights of the XXI annual meeting of the Brazilian Society of Protozoology, the XXXII annual meeting on Basic Research in Chagas' disease & an international symposium on vesicle trafficking in parasitic Protozoa – 7 to 9 November 2005, Caxambu, Minas Gerais, Brazil

This report focuses on the 2005 Annual meeting held in Caxambu, Minas Gerais, Brazil that was convened and organized by the Brazilian Society of Protozoology http://www.sbpz.org.br/. This is an annual event and details of these meetings can be found on the Society's website. Within the space available it has been impossible to cover all the important and fascinating contributions and what is presented are our personal views of the meetings scientific highlights and new developments. The contents undoubtedly reflect each author's scientific interests and expertise. Fuller details of the round tables, seminars and posters can be consulted on line at http://www.sbpz.org.br/livroderesumos2005.php.

Aortic distensibility measured by pulse-wave velocity is not modified in patients with Chagas' disease

Abstract Background Experimental studies demonstrate that infection with trypanosoma cruzi causes vasculitis. The inflammatory lesion process could hypothetically lead to decreased distensibility of large and small arteries in advanced Chagas' disease. We tested this hypothesis. Methods and results We evaluated carotid-femoral pulse-wave velocity (PWV) in 53 Chagas' disease patients compared with 31 healthy volunteers (control group). The 53 patients were classified into 3 groups: 1) 16 with indeterminate form of Chagas' disease; 2) 18 with Chagas' disease, electrocardiographic abnormalities, and normal systolic function; 3) 19 with Chagas' disease, systolic dysfunction, and mild-to-moderate congestive heart failure. No difference was noted between the 4 groups regarding carotid-femoral PWV (8.4 ± 1.1 vs 8.2 ± 1.5 vs 8.2 ± 1.4 vs 8.7 ± 1.6 m/s, P = 0.6) or pulse pressure (39.5 ± 7.6 vs 39.3 ± 8.1 vs 39.5 ± 7.4 vs 39.7 ± 6.9 mm Hg, P = 0.9). A positive, significant, similar correlation occurred between PWV and age in patients with Chagas' disease (r = 0.42, P = 0.002), in controls (r = 0.48, P = 0.006), and also between PWV and systolic blood pressure in both groups (patients with Chagas' disease, r = 0.38, P = 0.005; healthy subjects, r = 0.36, P = 0.043). Conclusion Carotid femoral pulse-wave velocity is not modified in patients with Chagas' disease, suggesting that elastic properties of large arteries are not affected in this disorder.

Discrepancies and consequences of indirect hemagglutination, indirect immunofluorescence and Elisa tests for the diagnosis of Chagas disease

Using the indirect hemagglutination (IH), indirect immunofluorescence (IIF) and enzyme linked immunosorbent assay (ELISA) tests for the diagnosis of Chagas disease, 4000 serum samples were examined. This study was conducted with different purposes: clinical interest, research support and parasitological monitoring of those patients with Chagas disease who were treated with heart transplantations. The tests occurred without patient selection and in accordance with the medical requests. The results showed discrepancies and brought about several questions, considering the different results that all three methods showed when considered together. What was found brought about concerns and we suggest the adoption of different measures, aiming to avoid these mismatches in the context of this disease.

Effects of vitamin C supplementation on acute phase Chagas disease in experimentally infected mice with Trypanosoma cruzi QM1 strain

The tissue changes that occur in Chagas disease are related to the degree of oxidative stress and antioxidant capacity of affected tissue. Studies with vitamin C supplementation did not develop oxidative damage caused by Chagas disease in the host, but other studies cite the use of peroxiredoxins ascorbate - dependent on T. cruzi to offer protection against immune reaction. Based on these propositions, thirty "Swiss" mice were infected with T. cruzi QM1 strain and treated with two different vitamin C doses in order to study the parasitemia evolution, histopathological changes and lipid peroxidation biomarkers during the acute phase of Chagas disease. The results showed that the parasite clearance was greater in animals fed with vitamin C overdose. There were no significant differences regarding the biomarkers of lipid peroxidation and inflammatory process or the increase of myocardium in animals treated with the recommended dosage. The largest amount of parasite growth towards the end of the acute phase suggests the benefit of high doses of vitamin C for trypomastigotes. The supplementation doesn't influence the production of free radicals or the number of amastigote nests in the acute phase of Chagas disease.

Performance of six diagnostic tests to screen for Chagas disease in blood banks and prevalence of Trypanosoma cruzi infection among donors with inconclusive serology screening based on the analysis of epidemiological variables

OBJECTIVE: The frequent occurrence of inconclusive serology in blood banks and the absence of a gold standard test for Chagas'disease led us to examine the efficacy of the blood culture test and five commercial tests (ELISA, IIF, HAI, c-ELISA, rec-ELISA) used in screening blood donors for Chagas disease, as well as to investigate the prevalence of Trypanosoma cruzi infection among donors with inconclusive serology screening in respect to some epidemiological variables. METHODS: To obtain estimates of interest we considered a Bayesian latent class model with inclusion of covariates from the logit link. RESULTS: A better performance was observed with some categories of epidemiological variables. In addition, all pairs of tests (excluding the blood culture test) presented as good alternatives for both screening (sensitivity > 99.96% in parallel testing) and for confirmation (specificity > 99.93% in serial testing) of Chagas disease. The prevalence of 13.30% observed in the stratum of donors with inconclusive serology, means that probably most of these are non-reactive serology. In addition, depending on the level of specific epidemiological variables, the absence of infection can be predicted with a probability of 100% in this group from the pairs of tests using parallel testing. CONCLUSION: The epidemiological variables can lead to improved test results and thus assist in the clarification of inconclusive serology screening results. Moreover, all combinations of pairs using the five commercial tests are good alternatives to confirm results.

Early dystrophin disruption in the pathogenesis of experimental chronic Chagas cardiomyopathy

Chronic Chagas cardiomyopathy evolves over a long period of time after initial infection by Trypanosoma cruzi. Similarly, a cardiomyopathy appears later in life in muscular dystrophies. This study tested the hypothesis that dystrophin levels are decreased in the early stage of T cruzi-infected mice that precedes the later development of a cardiomyopathy. CD1 mice were infected with T cruzi (Brazil strain), killed at 30 and 100 days post infection (dpi), and the intensity of inflammation, percentage of interstitial fibrosis, and dystrophin levels evaluated. Echocardiography and magnetic resonance imaging data were evaluated from 15 to 100 dpi. At 30 dpi an intense acute myocarditis with ruptured or intact intracellular parasite nests was observed. At 100 dpi a mild chronic fibrosing myocarditis was detected without parasites in the myocardium. Dystrophin was focally reduced or completely lost in cardiomyocytes at 30 dpi, with the reduction maintained up to 100 dpi. Concurrently, ejection fraction was reduced and the right ventricle was dilated. These findings support the hypothesis that the initial parasitic infection-induced myocardial dystrophin reduction/loss, maintained over time, might be essential to the late development of a cardiomyopathy in mice. (C) 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.