Genetic and functional role of TNF-alpha in the development Trypanosoma cruzi infection

Microalgae extracts modulates the immune response in Trypanosoma cruzi-infected human cells

Chagas disease (CD) is caused by the hemoflagellate protozoan Trypanosoma cruzi. The control of the infection depends of the innate and acquired immune response of host. Moreover, CD plays a significant role in the immune response, and, in this context, microalgae can be an interesting alternative due to its immunomodulatory and trypanocidal effects. This study aimed to evaluate, in vitro, immunomodulatory potentials of the aqueous extracts of Chlorella vulgaris and Tetradesmus obliquus. Both microalgae extracts (ME) were obtained by sonication, and the selectivity index (SI) was determined by assays of inhibitory concentration (IC50) in T. cruzi trypomastigotes cells; as well as the cytotoxic concentrations (CC50) in human peripheral mononuclear cells (PBMC). The immune response was evaluated in T. cruzi-infected PBMC using the IC50 value. ME led to inhibition of T. cruzi trypomastigotes after 24 h of treatment, in which the IC50 values were 112.1 µg/ml to C. vulgaris and 15.8 µg ml-1 to T. obliquus. On the other hand, C. vulgaris did not affect the viability of PBMCs in concentrations up to 1000 µg ml-1, while T. obliquus was non-toxic to PBMCs in concentrations up to 253.44 µg ml-1. In addition, T. obliquus displayed a higher SI against T. cruzi (SI = 16.8), when compared with C. vulgaris (SI = 8.9). C. vulgaris decreased the levels of IFN, indicating a reduction of the inflammatory process; while T. obliquus displayed an interesting immunomodulatory effect, since discretely increased the levels of TNF and stimulated the production of the anti-inflammatory cytokine IL-10. This study confirms that ME are effective against T. cruzi trypomastigotes, and may able to control the parasitemia and preventing the progress of CD while regulating the inflammatory process.

Cytokine Networks as Targets for Preventing and Controlling Chagas Heart Disease

Chagas disease, a neglected disease caused by the protozoan Trypanosoma cruzi, is endemic in 21 Latin American countries, affecting 6-8 million people. Increasing numbers of Chagas disease cases have also been reported in non-endemic countries due to migration, contamination via blood transfusions or organ transplantation, characterizing Chagas as an emerging disease in such regions. While most individuals in the chronic phase of Chagas disease remain in an asymptomatic clinical form named indeterminate, approximately 30% of the patients develop a cardiomyopathy that is amongst the deadliest cardiopathies known. The clinical distinctions between the indeterminate and the cardiac clinical forms are associated with different immune responses mediated by innate and adaptive cells. In this review, we present a collection of studies focusing on the human disease, discussing several aspects that demonstrate the association between chemokines, cytokines, and cytotoxic molecules with the distinct clinical outcomes of human infection with Trypanosoma cruzi. In addition, we discuss the role of gene polymorphisms in the transcriptional control of these immunoregulatory molecules. Finally, we discuss the potential application of cytokine expression and gene polymorphisms as markers of susceptibility to developing the severe form of Chagas disease, and as targets for disease control.

Chagas Disease Megaesophagus Patients Carrying Variant MRPS18B P260A Display Nitro-Oxidative Stress and Mitochondrial Dysfunction in Response to IFN-γ Stimulus

Chagas disease (CD), caused by the protozoan parasite Trypanosoma cruzi, affects 8 million people, and around 1/3 develop chronic cardiac (CCC) or digestive disease (megaesophagus/megacolon), while the majority remain asymptomatic, in the indeterminate form of Chagas disease (ASY). Most CCC cases in families with multiple Chagas disease patients carry damaging mutations in mitochondrial genes. We searched for exonic mutations associated to chagasic megaesophagus (CME) in genes essential to mitochondrial processes. We performed whole exome sequencing of 13 CME and 45 ASY patients. We found the damaging variant MRPS18B 688C > G P230A, in five out of the 13 CME patients (one of them being homozygous; 38.4%), while the variant appeared in one out of 45 ASY patients (2.2%). We analyzed the interferon (IFN)-γ-induced nitro-oxidative stress and mitochondrial function of EBV-transformed lymphoblastoid cell lines. We found the CME carriers of the mutation displayed increased levels of nitrite and nitrated proteins; in addition, the homozygous (G/G) CME patient also showed increased mitochondrial superoxide and reduced levels of ATP production. The results suggest that pathogenic mitochondrial mutations may contribute to cytokine-induced nitro-oxidative stress and mitochondrial dysfunction. We hypothesize that, in mutation carriers, IFN-γ produced in the esophageal myenteric plexus might cause nitro-oxidative stress and mitochondrial dysfunction in neurons, contributing to megaesophagus.

Insights into IL-33 on inflammatory response during in vitro infection by Trypanosoma cruzi

Inflammatory and regulatory cytokines play an important role in the immunopathogenesis of Trypanosoma cruzi infection. Interleukin (IL)-33 is a member of the IL-1 superfamily of cytokines whose expression/production is upregulated following pro-inflammatory stimulation to alert the immune system in response to tissue stress or damage. The aim of this study was to evaluate the inflammatory profile induced in cultured J774 cells stimulated or not with IL-33 (10 ng/mL), with live parasites (1 × 10⁶ metacyclic trypomastigote forms) and/or total antigen, TcAg (100 µg/mL) and with both, IL-33 and TcAg/T. cruzi. The cultures were evaluated at 24 h and 48 h after addition of the stimuli. For this, the supernatants were collected for the measurement of TNF, IL-17, CCL2, and IL-10 by ELISA and of nitrite by the Griess method. TNF, IL-17, and CCL2 concentrations were elevated in the presence of TcAg or live T. cruzi parasites at 24 h, and the addition of IL-33 potentiated these effects at 48 h. In addition, the T. cruzi-amastigote forms reduced in those infected J774 cells stimulated with IL-33 at 48 h. In conclusion, the IL-33 elevated the production of the TNF, IL-17, and CCL2 in cultured J774 cells stimulated with T. cruzi and/or its antigen and reduced the intracellular parasites, providing impetus to new investigations on its potential actions on the parasite-induced inflammation.

Coagulation disorders in Chagas disease: A pathophysiological systematic review and meta-analysis

BACKGROUND

Currently, Chagas disease (CD) constitutes one of the main public health problems in Latin America. However, little is known about potential mechanisms of disease different from cardiac or digestive involvement, such as the coagulation disorders elicited by the parasite persistence in the tissues. The aim of this systematic review was to describe and characterize all the published literature that evaluated the pathophysiological aspects of coagulation disorders in CD.

METHODS

Searches in Medline, EMBASE, and LILACS databases (from inception to July 28th, 2020) were performed. Articles of any language reporting the levels of different coagulation factors/markers or the prevalence of abnormal levels of the mentioned molecules in patients with CD were included. Two reviewers independently selected the studies, extracted the data, and assessed the quality of evidence. Estimates were pooled using random-effects meta-analyses.

RESULTS

Seven studies evaluating a total of 676 participants fulfilled the criteria and were included, while only six were suitable for meta-analyzing (544 participants, 52% men, mean age: 49 ± 8 years). 57.16% of the patients in the meta-analysis had a serological confirmed diagnosis of CD, while 97% of these were in the indeterminate stage of the disease. Patients in the CD group had higher levels of F 1 + 2 (SMD 5.15. 95% CI 1.92, 8.38), PAI-1 (SMD 0.46. 95% CI 0.07; 0.89), and P-selectin (SMD 1.8; 95% CI 0.13-3.47) compared to healthy controls. Furthermore, benznidazole therapy was associated with a reduction in the levels of these biomarkers after treatment.

CONCLUSION

The results of the present study suggest that patients with chronic T. cruzi infection are affected by a potential hypercoagulable state irrespective of the development of cardiac or digestive disease. Furthermore, the reduction in the levels of the coagulation markers after benznidazole therapy may suggest a significant role of the parasite load in the development of these coagulation disorders. There is a scarcity of research assessing the molecular and pathophysiological mechanisms of coagulation disorders in Chagas disease. Further research is needed to assess the benefit of benznidazole therapy on this hypercoagulable state in the long-term, along with its impact on the risk of thromboembolic events in CD patients.

Understanding the oral transmission of Trypanosoma cruzi as a veterinary and medical foodborne zoonosis

Chagas disease is a neglected tropical disease transmitted by the protozoan Trypanosoma cruzi that lately has been highlighted because several outbreaks attributed to oral transmission of the parasite have occurred. These outbreaks are characterized by high mortality rates and massive infections that cannot be related to other types of transmission such as the vectorial route. Oral transmission of Chagas disease has been reported in Brazil, Colombia, Venezuela, Bolivia, Ecuador, Argentina and French Guiana, most of them are massive oral outbreaks caused by the ingestion of beverages and food contaminated with triatomine feces or parasites' reservoirs secretions and considered since 2012 as a foodborne disease. In this review, we present the current status and all available data regarding oral transmission of Chagas disease, highlighting its relevance as a veterinary and medical foodborne zoonosis.

Effects of Meglumine Antimoniate Treatment on Cytokine Production in a Patient with Mucosal Leishmaniasis and Chagas Diseases Co-Infection

The influence of antimoniate treatment on specific anti-protozoan T-cell responses was evaluated in a 48-year-old male patient diagnosed with mucosal leishmaniasis and Chagas disease infection. Before and after treatment, PBMC (peripheral blood mononuclear cells) were cultured in the absence or presence of Leishmania braziliensis or Trypanosoma cruzi live parasites, their soluble antigens, or PHA (phytohaemagglutinin). Cytokines were measured and Treg (T regulatory) cell percentages were quantified. Before treatment, PBMC were able to produce higher amounts of TNF-α, IL-6 (Interleukin-6), and IL-10 (Interleukin-10) but lower amounts of IL-12 (Interleukin-12) in response to culture stimulation. However, after treatment, there was a down-modulation of TNF-α, IL-6, and IL-10 cytokines but an up-modulation in IL-12 production. PBMC had the ability to produce TNF-α only against live parasites or PHA. There was an overall decrease of circulating Treg cells after treatment. In mixed Leishmaniasis and Chagas disease infection, treatment with antimoniate could modulate immune responses toward a more protective profile to both diseases.

Genomic medicine in Chagas disease

Genetic approaches have been proposed for improving the understanding of the causes of differential susceptibility to Trypanosoma cruzi infection and Chagas disease outcome. Polymorphisms in genes involved in the immune/inflammatory response are being studied in order to clarify their possible role in the occurrence or severity of the cardiac and/or gastrointestinal complications. However still today, the number of significant associated genes is limited and the pathophysiological mechanisms underlying this condition are unknown. This article review the information currently available from the published scientific literature regarding the genetic variants of molecules of the immune system and other variants that can contribute to the clinical presentation of the disease. Genomic medicine will improve our knowledge about the molecular basis of Chagas disease, will open new avenues for developing biomarkers of disease progression, new therapeutic strategies to suit the requirements of individual patients, and will contribute to the control of one of the infections with the greatest socio-economic impact in the Americas.

Congenital Transmission of Trypanosoma cruzi: A Review About the Interactions Between the Parasite, the Placenta, the Maternal and the Fetal/Neonatal Immune Responses

Chagas disease (CD), caused by the protozoan parasite Trypanosoma cruzi, is considered a neglected tropical disease by the World Health Organization. Congenital transmission of CD is an increasingly relevant public health problem. It progressively becomes the main transmission route over others and can occur in both endemic and non-endemic countries. Though most congenitally infected newborns are asymptomatic at birth, they display higher frequencies of prematurity, low birth weight, and lower Apgar scores compared to uninfected ones, and some suffer from severe symptoms. If not diagnosed and treated, infected newborns are at risk of developing disabling and life-threatening chronic pathologies later in life. The success or failure of congenital transmission depends on interactions between the parasite, the placenta, the mother, and the fetus. We review and discuss here the current knowledge about these parameters, including parasite virulence factors such as exovesicles, placental tropism, potential placental defense mechanisms, the placental transcriptome of infected women, gene polymorphism, and the maternal and fetal/neonatal immune responses, that might modulate the risk of T. cruzi congenital transmission.

Association study between CCR2-CCR5 genes polymorphisms and chronic Chagas heart disease in Wichi and in admixed populations from Argentina

Several studies have proposed different genetic markers of susceptibility to develop chronic Chagas cardiomyopathy (CCC). Many genes may be involved, each one making a small contribution. For this reason, an appropriate approach for this problematic is to study a large number of single nucleotide polymorphisms (SNPs) in individuals sharing a genetic background. Our aim was to analyze two CCR2 and seven CCR5 SNPs and their association to CCC in Argentina. A case-control study was carried out in 480 T. cruzi seropositive adults from Argentinean Gran Chaco endemic region (Wichi and Creole) and patients from Buenos Aires health centres. They were classified according to the Consensus on Chagas-Mazza Disease as non-demonstrated (non-DC group) or demonstrated (DC group) cardiomyopathy, i.e. asymptomatic or with CCC patients, respectively. Since, after allelic analysis, 2 out of 9 studied SNPs did not fit Hardy–Weinberg equilibrium in the unaffected non-DC group from Wichi patients, we analyzed them as a separate population. Only rs1800024T and rs41469351T in CCR5 gene showed significant differences within non-Wichi population (Creole + patients from Buenos Aires centres), being the former associated to protection, and the latter to risk of CCC. No evidence of association was observed between any of the analyzed CCR2-CCR5 gene polymorphisms and the development of CCC; however, the HHE haplotype was associated with protection in Wichi population. Our findings support the hypothesis that CCR2-CCR5 genes and their haplotypes are associated with CCC; however, depending on the population studied, different associations can be found. Therefore, the evolutionary context, in which the genes or haplotypes are associated with diseases, acquires special relevance.

Chagas disease caused by the infection with the protozoan Trypanosoma cruzi is endemic in Latin America. In Argentina, it is estimated 1.5 million patients have Chagas disease and 2.2 million people in risk of T. cruzi infection. The endemic area covers the north of the country where the conditions, such as high levels of poverty and social exclusion and low population density, mostly rural, favor T. cruzi infection. Most affected people remains asymptomatic after infection for the rest of their lives, but around one third of infected people may develop clinical symptoms of visceral damage. Chronic Chagas Cardiomyopathy (CCC), the most frequent and severe consequence of the chronic infection by T. cruzi, is manifested predominately as an arrhythmogenic cardiomyopathy. The pathogenesis of CCC is not completely understood, but it is believed that the human genetic variation may be a determinant factor of disease progression. We studied in Wichi and in admixed populations from Argentina the CCR2-CCR5 genes, two CC chemokine receptors involved in the trafficking of several immune cells and in the pathogenesis of cardiovascular diseases. Our results showed that CCR2-CCR5 genes are associated with CCC and highlight the relevance of the evolutionary context in which disease-associated genes are found.

Biomarkers of Oxidative Stress and Inflammation in Chagasic Myocardiopathy

Introduction:

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

Objective:

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

Aim:

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

Results and Conclusion:

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

Disease Tolerance and Pathogen Resistance Genes May Underlie Trypanosoma cruzi Persistence and Differential Progression to Chagas Disease Cardiomyopathy

Chagas disease is caused by infection with the protozoan Trypanosoma cruzi and affects over 8 million people worldwide. In spite of a powerful innate and adaptive immune response in acute infection, the parasite evades eradication, leading to a chronic persistent infection with low parasitism. Chronically infected subjects display differential patterns of disease progression. While 30% develop chronic Chagas disease cardiomyopathy (CCC)—a severe inflammatory dilated cardiomyopathy—decades after infection, 60% of the patients remain disease-free, in the asymptomatic/indeterminate (ASY) form, and 10% develop gastrointestinal disease. Infection of genetically deficient mice provided a map of genes relevant for resistance to T. cruzi infection, leading to the identification of multiple genes linked to survival to infection. These include pathogen resistance genes (PRG) needed for intracellular parasite destruction, and genes involved in disease tolerance (protection against tissue damage and acute phase death—DTG). All identified DTGs were found to directly or indirectly inhibit IFN-γ production or Th1 differentiation. We hypothesize that the absolute need for DTG to control potentially lethal IFN-γ PRG activity leads to T. cruzi persistence and establishment of chronic infection. IFN-γ production is higher in CCC than ASY patients, and is the most highly expressed cytokine in CCC hearts. Key DTGs that downmodulate IFN-γ, like IL-10, and Ebi3/IL27p28, are higher in ASY patients. Polymorphisms in PRG and DTG are associated with differential disease progression. We thus hypothesize that ASY patients are disease tolerant, while an imbalance of DTG and IFN-γ PRG activity leads to the inflammatory heart damage of CCC.

Impact of Trypanosoma cruzi infection on nitric oxide synthase and arginase expression and activity in young and elderly mice

Elderly organisms are more susceptible to infectious diseases. However, the impact of aging on antiparasitic mechanisms, especially the nitric oxide pathway, is poorly understood. Using an integrated in vivo and in vitro model, we compared the severity of Trypanosoma cruzi infection in young and elderly (8 or 72 weeks old) mice. Forty C57BL/6 mice were randomized into four groups: Y-inf, young infected; Yn-inf, young uninfected; A-inf, aged infected; An-inf, aged uninfected. Parasitemia was measured daily, and animals were euthanized after 15 days of infection. Trypanosoma cruzi-induced inflammatory processes were analyzed in blood and heart samples, as well as in bone marrow-derived macrophages (BMDMs) co-cultured with splenocytes isolated from young or elderly mice. Our results indicated upregulated IgG2b and IL-17 production in elderly animals, which was not sufficient to reduce parasitemia, parasitic load and myocarditis to levels observed in young animals. The higher susceptibility of elderly mice to T. cruzi infection was accompanied by reduced cardiac inducible nitric oxide synthase (iNOS) gene expression, nitric oxide (NO) and IFN-γ levels, as well as an antagonistic upregulation of arginase-1 expression and arginase activity. The same responses were observed when BMDMs co-cultured with splenocytes from elderly mice were stimulated with T. cruzi antigens. Our findings indicate that elderly mice were more susceptible to T. cruzi infection, which was potentially related to an attenuated response to antigenic stimulation, inhibition of iNOS gene expression and NO production, and antagonistic upregulation of arginase gene expression and activity, which created favorable conditions for heart parasitism and myocarditis development.

A systematic review of the Trypanosoma cruzi genetic heterogeneity, host immune response and genetic factors as plausible drivers of chronic chagasic cardiomyopathy

Chagas disease is a complex tropical pathology caused by the kinetoplastid Trypanosoma cruzi. This parasite displays massive genetic diversity and has been classified by international consensus in at least six Discrete Typing Units (DTUs) that are broadly distributed in the American continent. The main clinical manifestation of the disease is the chronic chagasic cardiomyopathy (CCC) that is lethal in the infected individuals. However, one intriguing feature is that only 30-40% of the infected individuals will develop CCC. Some authors have suggested that the immune response, host genetic factors, virulence factors and even the massive genetic heterogeneity of T. cruzi are responsible of this clinical pattern. To date, no conclusive data support the reason why a few percentages of the infected individuals will develop CCC. Therefore, we decided to conduct a systematic review analysing the host genetic factors, immune response, cytokine production, virulence factors and the plausible association of the parasite DTUs and CCC. The epidemiological and clinical implications are herein discussed.

Single nucleotide polymorphisms of cytokine-related genes and association with clinical outcome in a Chagas disease case-control study from Brazil

BACKGROUND

The severity of chronic chagasic cardiomyopathy (CCC), the most frequent clinical outcome of Chagas disease (CD), has been associated with cytokine-enriched heart tissue inflammation, and high serum levels of transforming growth factor (TGFβ), interferon-gamma (IFNγ), and tumour necrosis factor (TNF). Conversely, increased interleukin (IL)-10 serum concentrations have been associated with asymptomatic CD. Cytokines and cytokine-related gene polymorphisms may control cytokine expression and have been proposed to contribute to CCC outcomes.

OBJECTIVES

We evaluated the association of 13 cytokine-related genes (TGFB: rs8179181, rs8105161, rs1800469; IL10: rs1800890, rs1800871, rs1800896; IFNG: rs2430561; TNF: rs1800629; BAT1: rs3853601; LTA: rs909253, rs2239704; TNFR1: rs767455; TNFR2: rs1061624) with risk and progression of CCC.

FINDINGS

Four hundred and six seropositive patients from CD endemic areas in the state of Pernambuco, north-eastern Brazil, were classified as non-cardiopathic (A, 110) or cardiopathic (mild, B1, 163; severe, C, 133). We found no evidence of TGFB, IL10, TNF, or TNFR1/2 gene polymorphisms associated with CCC risk or progression. Only BAT1 rs3853601 −22G carriers (B1 vs. C: OR = 0.5; p-value = 0.03) and IFNG rs2430561 +874AT (A vs. C: OR = 0.7; p-value = 0.03; A vs. B1+C: OR = 0.8; p-value = 0.02) showed a significant association with protection from cardiopathy in a logistic regression analysis with adjustment for gender and ethnicity; however, the association disappeared after performing adjustment for multiple testing. A systematic review of TNF rs1800629 −308G>A publications included five studies for meta-analysis (534 CCC and 472 asymptomatic patients) and showed no consensus in pooled odds ratio (OR) estimates for A allele or A carriers (OR = 1.4 and 1.5; p-values = 0.14 and 0.15, respectively). In CD patients, TNF serum levels were increased, but not affected by the TNF rs1800629 −308A allele.

MAIN CONCLUSIONS

Our data suggest no significant contribution of the analysed gene variants of cytokine-related molecules to development/severity of Chagas' heart disease, reinforcing the idea that parasite/host interplay is critical to CD outcomes.

Renovascular hypertension increases serum TNF and CX3CL1 in experimental Trypanosoma cruzi infection

Trypanosoma cruzi triggers a progressive inflammatory response affecting cardiovascular functions in humans and experimental models. Angiotensin II, a key effector of the renin-angiotensin system, plays roles in mediating hypertension, heart failure, and inflammatory responses. T. cruzi and AngII can induce inflammatory responses by releasing inflammatory mediators. The aim of this study was to evaluate systemic AngII, tumor necrosis factor (TNF), and CX3CL1 mediators in a two-kidney one-clip (2K1C) renovascular hypertension model using Wistar rats infected with T. cruzi. Our data showed an increase in serum AngII in uninfected and T. cruzi-infected rats 1 week after 2K1C surgery compared to non-2K1C (Sham) animals. The baseline systolic blood pressure was higher in both uninfected and infected 2K1C rats. Despite no difference in circulating parasites in the acute phase of infection, elevated serum TNF and CX3CL1 were observed at 8 weeks post-infection in 2K1C rats in association with higher cardiac inflammatory infiltration. In summary, AngII-induced hypertension associated with T. cruzi infection may act synergistically to increase TNF and CX3CL1 in the 2K1C rat model, thereby intensifying cardiac inflammatory infiltration and worsening the underlying inflammation triggered by this protozoan.

T cells responding to Trypanosoma cruzi detected by membrane TNF-α and CD154 in chagasic patients

Introduction

Chagas disease is a parasitic infection whose pathogenesis is related to parasite persistence and a dysfunctional cellular immune response. Variability in cytokine secretion among chronic Trypanosoma cruzi‐infected patients might preclude the identification of the pool of antigen specific T cells. The goal of this study was to determine the fraction of T cells responding to T. cruzi antigen measured by the expression of membrane TNF‐α and CD154.

Methods

A total of 21 chagasic patients, 11 healthy and 5 non‐chagasic cardiomyopathy controls were analyzed. PBMCs were short‐term cultured in the presence of anti‐CD28, anti‐CD49d, anti‐TNF‐α, and TACE (TNF‐α converting enzyme) inhibitor either under T. cruzi‐lysate or polyclonal stimuli. Cells were stained with anti‐CD3, anti‐CD4, anti‐CD8, and anti‐CD154, and analyzed with flow cytometry.

Results

CD4+ and CD8+ T cells in chagasic patients displayed higher percentages of membrane‐bound TNF‐α+ and CD154+ compared with controls after T. cruzi‐antigen stimulation. Both markers displayed a positive correlation in the T cell subpopulations analyzed. Symptomatic chagasic patients were differentiated from asymptomatic patients based on the expression of CD154 and membrane TNF‐α in TCD4+ and TCD8+ compartments, respectively.

Conclusions

These results show that both markers could be useful for assessing the pool of antigen‐specific T cells in chronic chagasic patients.

Cynomolgus macaques naturally infected with Trypanosoma cruzi-I exhibit an overall mixed pro-inflammatory/modulated cytokine signature characteristic of human Chagas disease

Background

Non-human primates have been shown to be useful models for Chagas disease. We previously reported that natural T. cruzi infection of cynomolgus macaques triggers clinical features and immunophenotypic changes of peripheral blood leukocytes resembling those observed in human Chagas disease. In the present study, we further characterize the cytokine-mediated microenvironment to provide supportive evidence of the utility of cynomolgus macaques as a model for drug development for human Chagas disease.

Methods and findings

In this cross-sectional study design, flow cytometry and systems biology approaches were used to characterize the ex vivo and in vitro T. cruzi-specific functional cytokine signature of circulating leukocytes from TcI-T. cruzi naturally infected cynomolgus macaques (CH). Results showed that CH presented an overall CD4⁺-derived IFN-γ pattern regulated by IL-10-derived from CD4⁺ T-cells and B-cells, contrasting with the baseline profile observed in non-infected hosts (NI). Homologous TcI-T. cruzi-antigen recall in vitro induced a broad pro-inflammatory cytokine response in CH, mediated by TNF from innate/adaptive cells, counterbalanced by monocyte/B-cell-derived IL-10. TcIV-antigen triggered a more selective cytokine signature mediated by NK and T-cell-derived IFN-γ with modest regulation by IL-10 from T-cells. While NI presented a cytokine network comprised of small number of neighborhood connections, CH displayed a complex cross-talk amongst network elements. Noteworthy, was the ability of TcI-antigen to drive a complex global pro-inflammatory network mediated by TNF and IFN-γ from NK-cells, CD4⁺ and CD8⁺ T-cells, regulated by IL-10⁺CD8⁺ T-cells, in contrast to the TcIV-antigens that trigger a modest network, with moderate connecting edges.

Conclusions

Altogether, our findings demonstrated that CH present a pro-inflammatory/regulatory cytokine signature similar to that observed in human Chagas disease. These data bring additional insights that further validate these non-human primates as experimental models for Chagas disease.

Trypanosoma cruzi is the causative agent of Chagas disease; millions of people are infected with this parasite. One of the major challenges to manage infected patients is the low efficacy of currently available treatments, especially during chronic infection. Different T. cruzi genotypes are known to differ in response to existing drugs (e.g., TcI is quite resistant), and differences among individuals in immune response also are believed to play a role determining therapeutic efficacy. Experimental models and in vitro systems have been proposed for rational searches for new compounds for treating infected individuals, optimally before the infection becomes clinically manifested as Chagas disease. In the field of drug development, the non-human primate models offer a unique and valuable contribution, as a consequence of patho-physiological similarities that mimic many human diseases, including Chagas disease. In the present study, we further investigated the functional features of the immune response triggered by TcI T. cruzi-infection, characterizing the ex vivo as well as the in vitro cytokine microenvironment, upon T. cruzi-antigen recall. Our results revealed that chronically infected cynomolgus macaques display a similar ex vivo cytokine signature to that observed in chronic human Chagas disease. Moreover, CH macaques display a complex cross-talk among the cytokine⁺ leukocyte subsets, enhanced by TcI T. cruzi-antigen recall in vitro. These findings provide additional insights that further validate these non-human primates as experimental models for rational development of new therapeutic agents for Chagas disease.

Evaluation of VDR gene polymorphisms in Trypanosoma cruzi infection and chronic Chagasic cardiomyopathy

Vitamin D is an important modulator of the immune response. It acts over several immune cell types where the Vitamin D receptor (VDR) is expressed. Due to the high relevance of this signaling pathway, several studies have investigated the possible influence of genes involved in the metabolism of Vitamin D and its receptor in different human diseases. Here, we analyzed whether four single-nucleotide polymorphisms of the VDR gene (rs731236, rs7975232, rs1544410 and rs2228570) are involved in the susceptibility to infection by Trypanosoma cruzi and/or to chronic Chagas cardiomyopathy (CCC) in a Colombian endemic population for this parasite. Our results showed that the rs2228570*A allele is associated with CCC development (P = 4.46E-03, OR = 1.51). In summary, the data presented in this report suggest that variation within the VDR gene may affect the immune response against T. cruzi, increasing the probability of cardiac complications in infected individuals.

Effects of aspirin-triggered resolvin D1 on peripheral blood mononuclear cells from patients with Chagas' heart disease

Chagas disease is caused by Trypanosoma cruzi (T. cruzi). In some patients with Chagas disease, symptoms progress to chronic chagasic cardiomyopathy. Endogenously, inflammation is resolved in the presence of lipid mediators such as aspirin-triggered RvD1 (AT-RvD1) which has anti-inflammatory and pro-resolution effects. Here, we demonstrated, for the first time, the effects of AT-RvD1 on T. cruzi antigen-stimulated peripheral blood mononuclear cells (PBMCs) from patients with Chagas heart disease. The levels of IFN-γ, TNF-α, IL-10, and IL-13 increased in PBMCs from cardiac-form Chagas patients in stage B1 (patients with fewer heart abnormalities) stimulated with T. cruzi antigen compared to those in non-stimulated PBMCs. AT-RvD1 reduced the IFN-γ concentrations in PBMCs from patients with Chagas disease stimulated with T. cruzi antigen compared to stimulated with T. cruzi antigen cells. AT-RvD1 treatment resulted in no observable changes in TNF-α, IL-10, and IL-13 levels. AT-RvD1 significantly decreased the percentage of necrotic cells and caused a significant reduction in the proliferation rate of T. cruzi antigen-stimulated PBMCs from patients with Chagas disease. These findings demonstrate that AT-RvD1 modulates the immune response in Chagas disease patients and might have potential to be used as an alternative approach for slowing the development of further heart damage.

The rs361525 polymorphism does not increase production of tumor necrosis factor alpha by monocytes from alpha-1 antitrypsin deficient subjects with chronic obstructive pulmonary disease - a pilot study

Background

Polymorphisms in the TNF-A gene have been associated with chronic obstructive pulmonary disease (COPD) in some case-control studies. Previous work has shown that COPD/chronic bronchitis subjects with alpha-1 antitrypsin deficiency with the rs361525 TNF-α single nucleotide polymorphism have 100 times more TNF-in spontaneous sputum than disease matched controls. Our objective was to determine if the presence of this polymorphism increased TNF-α production by blood monocytes from COPD subjects.

Findings

Monocytes from 18 COPD/alpha-1 antitrypsin deficient subjects, with and without the rs361525 polymorphism, were cultured in the presence or absence of lipopolysaccharide. Cell-free supernatants were analyzed by ELISA and real-time PCR performed using cDNA from extracted RNA. Baseline expression of TNF-α messenger RNA was no different between the groups. No difference in messenger RNA or secreted protein was observed over time in un-stimulated cells. TNF-α messenger RNA expression and protein was not higher in lipopolysaccharide-stimulated monocytes from subjects with the polymorphism compared to cells from patients with the wild-type allele.

Conclusions

This small pilot study did not provide an explanation for the findings of earlier observations of the association of the rs361525 polymorphism with TNF-α in airways secretions. Possible reasons for the lack of concordance include the study of blood rather than tissue cells, the use of a single stimulant rather than biological secretions and the need for far greater subject numbers to overcome intra-subject variation in monocyte TNF-α production.

Investigation of the role of IL17A gene variants in Chagas disease

Human host genetic factors have been suggested to be determinants of the prevalence and clinical forms of Chagas disease. In this regard, IL-17A is believed to control parasitemia and protect against heart disease. In this work, we assessed whether IL17A gene polymorphisms are related to infection and/or development of the cardiac form of Chagas disease by genotyping for five IL17A SNPs (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909) in 1171 individuals from a Colombian region endemic for Chagas disease, classified as seronegative (n=595), seropositive asymptomatic (n=175) and chronic Chagas cardiomyopathy (n=401). Our results showed that SNP rs8193036, which is located upstream of the coding region of the gene, was slightly associated with protection against T. cruzi infection (P=0.0170, P(FDR)=0.0851, odds ratio (OR)=0.80, confidence interval (CI)=0.66-0.96) and associated with protection against the development of cardiomyopathy (P=0.0065, P(FDR)=0.0324, OR=0.75, CI=0.60-0.92). This finding suggests that this IL17A polymorphism could be associated with Trypanosoma cruzi infection and the development of chronic cardiomyopathy due to differential expression of cytokine IL-17A.

Inflammatory responses and intestinal injury development during acute Trypanosoma cruzi infection are associated with the parasite load

Background

Chagas disease is caused by the protozoan Trypanosoma cruzi and is characterized by cardiac, gastrointestinal, and nervous system disorders. Although much about the pathophysiological process of Chagas disease is already known, the influence of the parasite burden on the inflammatory process and disease progression remains uncertain.

Methods

We used an acute experimental disease model to evaluate the effect of T. cruzi on intestinal lesions and assessed correlations between parasite load and inflammation and intestinal injury at 7 and 14 days post-infection. Low (3 × 10²), medium (3 × 10³), and high (3 × 10⁴) parasite loads were generated by infecting C57BL/6 mice with “Y”-strain trypomastigotes. Statistical analysis was performed using analysis of variance with Tukey’s multiple comparison post-test, Kruskal–Wallis test with Dunn’s multiple comparison, χ2 test and Spearman correlation.

Results

High parasite load-bearing mice more rapidly and strongly developed parasitemia. Increased colon width, inflammatory infiltration, myositis, periganglionitis, ganglionitis, pro-inflammatory cytokines (e.g., TNF-α, INF-γ, IL-2, IL-17, IL-6), and intestinal amastigote nests were more pronounced in high parasite load-bearing animals. These results were remarkable because a positive correlation was observed between parasite load, inflammatory infiltrate, amastigote nests, and investigated cytokines.

Conclusions

These experimental data support the idea that the parasite load considerably influences the T. cruzi-induced intestinal inflammatory response and contributes to the development of the digestive form of the disease.

Human leucocyte antigen-G (HLA-G) and its murine functional homolog Qa2 in the Trypanosoma cruzi Infection

Genetic susceptibility factors, parasite strain, and an adequate modulation of the immune system seem to be crucial for disease progression after Trypanosoma cruzi infection. HLA-G and its murine functional homolog Qa2 have well-recognized immunomodulatory properties. We evaluated the HLA-G 3′ untranslated region (3′UTR) polymorphic sites (associated with mRNA stability and target for microRNA binding) and HLA-G tissue expression (heart, colon, and esophagus) in patients presenting Chagas disease, stratified according to the major clinical variants. Further, we investigated the transcriptional levels of Qa2 and other pro- and anti-inflammatory genes in affected mouse tissues during T. cruzi experimental acute and early chronic infection induced by the CL strain. Chagas disease patients exhibited differential HLA-G 3′UTR susceptibility allele/genotype/haplotype patterns, according to the major clinical variant (digestive/cardiac/mixed/indeterminate). HLA-G constitutive expression on cardiac muscle and colonic cells was decreased in Chagasic tissues; however, no difference was observed for Chagasic and non-Chagasic esophagus tissues. The transcriptional levels of Qa2 and other anti and proinflammatory (CTLA-4, PDCD1, IL-10, INF-γ, and NOS-2) genes were induced only during the acute T. cruzi infection in BALB/c and C57BL/6 mice. We present several lines of evidence indicating the role of immunomodulatory genes and molecules in human and experimental T. cruzi infection.

Presence of antigen-experienced T cells with low grade of differentiation and proliferative potential in chronic Chagas disease myocarditis

BACKGROUND

The main consequence of chronic Trypanosoma cruzi infection is the development of myocarditis in approximately 20-30% of infected individuals but not until 10-20 years after the initial infection. We have previously shown that circulating interferon-γ-secreting T cells responsive to Trypanosoma cruzi antigens in chronic Chagas disease patients display a low grade of differentiation and the frequency of these T lymphocytes decreases along with the severity of heart disease. This study thought to explore the expression of inhibitory receptors, transcription factors of type 1 or regulatory T cells, and markers of T cell differentiation, immunosenescence or active cell cycle in cardiac explants from patients with advanced Chagas disease myocarditis.

METHODOLOGY/PRINCIPAL FINDINGS

The expression of different markers for T and B cells as well as for macrophages was evaluated by immunohistochemistry and immunofluorescence techniques in cardiac explants from patients with advanced chronic Chagas disease submitted to heart transplantation. Most infiltrating cells displayed markers of antigen-experienced T cells (CD3(+), CD4(+), CD8(+), CD45RO(+)) with a low grade of differentiation (CD27(+), CD57(-), CD45RA(-), PD(-)1(-)). A skewed T helper1/T cytotoxic 1 profile was supported by the expression of T-bet; whereas FOXP3(+) cells were scarce and located only in areas of severe myocarditis. In addition, a significant proliferative capacity of CD3(+) T cells, assessed by Ki67 staining, was found.

CONCLUSIONS/SIGNIFICANCE

The quality of T cell responses and immunoregulatory mechanisms might determine the pattern of the cellular response and the severity of disease in chronic Trypanosoma cruzi infection.

Cytokine profiling in Chagas disease: towards understanding the association with infecting Trypanosoma cruzi discrete typing units (a BENEFIT TRIAL sub-study)

BACKGROUND

Chagas disease caused by the protozoan Trypanosoma cruzi is an important public health problem in Latin America. The immunological mechanisms involved in Chagas disease pathogenesis remain incompletely elucidated. The aim of this study was to explore cytokine profiles and their possible association to the infecting DTU and the pathogenesis of Chagas disease.

METHODS

109 sero-positive T. cruzi patients and 21 negative controls from Bolivia and Colombia, were included. Flow cytometry assays for 13 cytokines were conducted on human sera. Patients were divided into two groups: in one we compared the quantification of cytokines between patients with and without chronic cardiomyopathy; in second group we compared the levels of cytokines and the genetic variability of T. cruzi.

RESULTS

Significant difference in anti-inflammatory and pro-inflammatory cytokines profiles was observed between the two groups cardiac and non-cardiac. Moreover, serum levels of IFN-γ, IL-12, IL-22 and IL-10 presented an association with the genetic variability of T.cruzi, with significant differences in TcI and mixed infections TcI/TcII.

CONCLUSION

Expression of anti-inflammatory and pro-inflammatory cytokines may play a relevant role in determining the clinical presentation of chronic patients with Chagas disease and suggests the occurrence of specific immune responses, probably associated to different T. cruzi DTUs.

Genetic susceptibility to Chagas disease: an overview about the infection and about the association between disease and the immune response genes

Chagas disease, which is caused by the flagellate parasite Trypanosoma cruzi, affects 8-10 million people in Latin America. The disease is endemic and is characterised by acute and chronic phases that develop in the indeterminate, cardiac, and/or gastrointestinal forms. The immune response during human T. cruzi infection is not completely understood, despite its role in driving the development of distinct clinical manifestations of chronic infection. Polymorphisms in genes involved in the innate and specific immune response are being widely studied in order to clarify their possible role in the occurrence or severity of disease. Here we review the role of classic and nonclassic MHC, KIR, and cytokine host genetic factors on the infection by T. cruzi and the clinical course of Chagas disease.

Combined treatment with benznidazole and allopurinol in mice infected with a virulentTrypanosoma cruziisolate from Nicaragua

We evaluated the effect of chemotherapy with a sequential combined treatment of a low dose of benznidazole and allopurinol, in different schedules of administration, in experimental models of acute and chronicTrypanosoma cruziinfection. Mice were infected with NicaraguaT. cruziisolate, a virulent parasite from an endemic area of Nicaragua, genotyped asTcI (Grossoet al. 2010). We assessed survival rate, IgG levels, histopathological studies and quantified parasitaemia. A 15% survival rate was recorded in untreated mice during the acute phase ofT. cruziinfection. Allopurinol administered immediately after benznidazole treatment was able to reduce parasitaemia and attenuate tissue damage by reducing inflammation.Trypanosoma cruzi-specific antibodies also decreased in 40–50% of the treated mice. The addition of allopurinol during the chronic phase showed the highest beneficial effect, not only by reducing parasitaemia but also by lowering the degree of inflammation and fibrosis.

Association between the lymphotoxin-alpha gene polymorphism and chagasic cardiopathy

Lymphotoxin-alpha (LT-alpha or LTA) is an inflammatory cytokine that is involved in the organization and maintenance of the inflammatory process and in the arrangement of cells at the site of inflammation. These features suggest an important role in the development of chronic Chagas' disease, especially the cardiac form. The objective of this study was to evaluate LT-alpha genetics and its biological role in chronic Chagas' disease. A total of 284 subjects were studied. The LT-alpha single-nucleotide polymorphism (+252) was analyzed by the polymerase chain reaction-restriction fragment length polymorphism and expression by enzyme-linked immunosorbent assay in culture supernatants and in individual T lymphocytes by flow cytometry. The risk of developing the cardiac form was 2.8 times higher among carriers of genotype GG and 2.4 times among carriers of genotype GA when compared to subjects carrying genotype AA. Seropositive subjects carrying the G allele produced significantly higher levels of LT-alpha. The cytokine was mainly expressed by CD8(+) T lymphocytes in the absence of any stimulus and after stimulation with the Trypanosoma cruzi antigen. This study provides genetic and biological evidence for an important role of LT-alpha in the development of the cardiac form of Chagas' disease.

In situ expression of regulatory cytokines by heart inflammatory cells in Chagas' disease patients with heart failure

Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi. The immune system plays an important role in the reduction of parasite load, but may also contribute to the development of lesions observed during the chronic phase of the disease. We analyzed cytokines produced by inflammatory heart cells in 21 autopsy samples obtained from patients with Chagas' disease divided according to the presence or absence of heart failure (HF). Left ventricular sections were analyzed by immunohistochemistry using antibodies against human IL-4, IFN-γ, TGF-β, TNF-α, and NOS2. In situ mRNA expression was quantified by a Low Density Array. The number of IFN-γ-positive cells was significantly higher than IL-4 positive cells. TNF-α, TGF-β and NOS2 were detected in 65%, 62% and 94% of samples respectively. There was an association between TNF-α-producing cells and the presence of HF. Subjects with HF presented higher levels of STAT4 mRNA, whereas FoxP3 and STAT6 levels were similar in the two groups. A Th1 cytokine pattern predominated in the cardiac inflammatory cell infiltrate of Chagas' disease patients associated with HF. High degree of fibrosis was associated with low NOS2 expression. These results support the idea that Th1 immune responses are involved in heart lesions of Chagas' disease patients.

Genetic susceptibility to chronic Chagas disease: an overview of single nucleotide polymorphisms of cytokine genes

Chagas disease is a parasitic infection that is a significant public health problem in Latin America. The mechanisms responsible for susceptibility to the infection and the mechanisms involved in the development of cardiac and digestive forms of chronic Chagas disease remain poorly understood. However, there is growing evidence that differences in susceptibility in endemic areas may be attributable to host genetic factors. The aim of this overview was to analyze the genetic susceptibility to human Chagas disease, particularly that of single nucleotide polymorphisms of cytokine genes. A review of the literature was conducted on the following databases: PubMed/MEDLINE and Scopus. The search strategy included using the following terms: "Cytokines", "Single Nucleotide Polymorphisms" and "Chagas Disease". After screening 25 citations from the databases, 19 studies were selected for the overview. A critical analysis of the data presented in the articles suggests that genetic susceptibility to Chagas disease and chronic Chagas cardiomyopathy is highly influenced by the complexity of the immune response of the host. Follow-up studies based on other populations where Chagas disease is endemic (with distinct ethnic and genetic backgrounds) need to be conducted. These should use a large sample population so as to establish what cytokine genes are involved in susceptibility to and/or progression of the disease.