The TGF-β Pathway as an Emerging Target for Chagas Disease Therapy

In Chagas disease, transforming growth factor beta neutralization reduces Trypanosoma cruzi infection and improves cardiac performance

Chronic Chagasic cardiomyopathy (CCC), a progressive inflammatory and fibrosing disease, is the most prominent clinical form of Chagas disease, a neglected tropical disease caused by Trypanosoma cruzi infection. During CCC, the parasite remains inside the cardiac cells, leading to tissue damage, involving extensive inflammatory response and irregular fibrosis. Among the fibrogenic factors is transforming growth factor-β (TGF-β), a key cytokine controlling extracellular matrix synthesis and degradation. TGF-β is involved in CCC onset and progression, with increased serum levels and activation of its signaling pathways in the cardiac tissue, which crucially contributes to fibrosis. Inhibition of the TGF-β signaling pathway attenuates T. cruzi infection and prevents cardiac damage in an experimental model of acute Chagas disease. The aim of this study was to investigate the effect of TGF-β neutralization on T. cruzi infection in both in vitro and in vivo pre-clinical models, using the 1D11 monoclonal antibody. To this end, primary cultures of cardiac cells were infected with T. cruzi trypomastigote forms and treated with 1D11. For in vivo studies, 1D11 was administered in different schemes for acute and chronic phase models (Swiss mice infected with 10⁴ parasites from the Y strain and C57BL/6 mice infected with 10² parasites from the Colombian strain, respectively). Here we show that the addition of 1D11 to cardiac cells greatly reduces cardiomyocyte invasion by T. cruzi and the number of parasites per infected cell. In both acute and chronic experimental models, T. cruzi infection altered the electrical conduction, decreasing the heart rate, increasing the PR interval and the P wave duration. The treatment with 1D11 reduced cardiac fibrosis and reversed electrical abnormalities improving cardiac performance. Taken together, these data further support the major role of the TGF-β signaling pathways in T. cruzi-infection and their biological consequences on parasite/host interactions. The therapeutic effects of the 1D11 antibody are promising and suggest a new possibility to treat cardiac fibrosis in the chronic phase of Chagas' heart disease by TGF-β neutralization.

Epigenetic regulation of transcription factor binding motifs promotes Th1 response in Chagas disease cardiomyopathy

Chagas disease, caused by the protozoan Trypanosoma cruzi, is an endemic parasitic disease of Latin America, affecting 7 million people. Although most patients are asymptomatic, 30% develop complications, including the often-fatal Chronic Chagasic Cardiomyopathy (CCC). Although previous studies have demonstrated some genetic deregulations associated with CCCs, the causes of their deregulations remain poorly described. Based on bulk RNA-seq and whole genome DNA methylation data, we investigated the genetic and epigenetic deregulations present in the moderate and severe stages of CCC. Analysis of heart tissue gene expression profile allowed us to identify 1407 differentially expressed transcripts (DEGs) specific from CCC patients. A tissue DNA methylation analysis done on the same tissue has permitted the identification of 92 regulatory Differentially Methylated Regions (DMR) localized in the promoter of DEGs. An in-depth study of the transcription factors binding sites (TFBS) in the DMRs corroborated the importance of TFBS’s DNA methylation for gene expression in CCC myocardium. TBX21, RUNX3 and EBF1 are the transcription factors whose binding motif appears to be affected by DNA methylation in the largest number of genes. By combining both transcriptomic and methylomic analysis on heart tissue, and methylomic analysis on blood, 4 biological processes affected by severe CCC have been identified, including immune response, ion transport, cardiac muscle processes and nervous system. An additional study on blood methylation of moderate CCC samples put forward the importance of ion transport and nervous system in the development of the disease.

The Search for Biomarkers and Treatments in Chagas Disease: Insights From TGF-Beta Studies and Immunogenetics

The anti-inflammatory cytokine transforming growth factor beta (TGF-β) plays an important role in Chagas disease (CD), a potentially life-threatening illness caused by Trypanosoma cruzi. In this review we revisited clinical studies in CD patients combined with in vitro and in vivo experiments, presenting three main sections: an overview of epidemiological, economic, and clinical aspects of CD and the need for new biomarkers and treatment; a brief panorama of TGF-β roles and its intracellular signaling pathways, and an update of what is known about TGF-β and Chagas disease. In in vitro assays, TGF-β increases during T. cruzi infection and modulates heart cells invasion by the parasite fostering its intracellular parasite cycle. TGF-β modulates host immune response and inflammation, increases heart fibrosis, stimulates remodeling, and slows heart conduction via gap junction modulation. TGF-β signaling inhibitors reverts these effects opening a promising therapeutic approach in pre-clinical studies. CD patients with higher TGF-β1 serum level show a worse clinical outcome, implicating a predictive value of serum TGF-β as a surrogate biomarker of clinical relevance. Moreover, pre-clinical studies in chronic T. cruzi infected mice proved that inhibition of TGF-β pathway improved several cardiac electric parameters, reversed the loss of connexin-43 enriched intercellular plaques, reduced fibrosis of the cardiac tissue, restored GATA-6 and Tbox-5 transcription, supporting cardiac recovery. Finally, TGF-β polymorphisms indicate that CD immunogenetics is at the base of this phenomenon. We searched in a Brazilian population five single-nucleotide polymorphisms (-800 G>A rs1800468, -509 C>T rs1800469, +10 T>C rs1800470, +25 G>C rs1800471, and +263 C>T rs1800472), showing that CD patients frequently express the TGF-β1 gene genotypes CT and TT at position -509, as compared to noninfected persons; similar results were observed with genotypes TC and CC at codon +10 of the TGF-β1 gene, leading to the conclusion that 509 C>T and +10 T>C TGF-β1 polymorphisms are associated with Chagas disease susceptibility. Studies in genetically different populations susceptible to CD will help to gather new insights and encourage the use of TGF-β as a CD biomarker.

Transforming growth factor-ß as a therapeutic target for the cardiac damage of Chagas disease

Transforming growth factor beta (TGF-β) is deeply involved on the pathogenesis of Chagas disease. Our group has been investigating the participation of this pleiotropic cytokine in different aspects of Chagas disease over the last 20 years. Important observations have been made, such as: (i) the ability of Trypanosoma cruzi in activating latent TGF-β; (ii) the potential involvement of TGF-β pathway on T. cruzi invasion of host cells; (iii) association of TGF-β with parasite intracellular replication; (iv) cardiac fibrosis development and maintenance; (v) disruption of Connexin-43 plaque structures and (vi) inflammation and immune response. In this perspective article we intend to discuss the advances of the potential use of new therapies targeting TGF-β to treat the cardiac alterations of Chagas disease-affected patients.

Interleukin-9 in Immunopathology of Trypanosoma cruzi Experimental Infection

Chagas’ disease is a parasitosis caused by Trypanosoma cruzi, which affects approximately 8 million people worldwide. The balance between pro- and anti-inflammatory cytokines produced during immunological responses contributes to disease prognosis and progression. Parasite tissue persistence can induce chronic inflammatory stimuli, which can cause long-term tissue injury and fibrosis. Chronic Chagas’ patients exhibit increased levels of interleukin (IL)-9, an important cytokine in the regulation of inflammatory and fibrogenic processes. Data on the role of IL-9 in other pathologies are sometimes contradictory, and few studies have explored this cytokine’s influence in Chagas’ disease pathology. Hence, the aim of this study was to evaluate the role of IL-9 in the progression of T. cruzi infection in vivo and in vitro. In vitro infection demonstrated that IL-9 reduced the number of infected cells and decreased the multiplication of intracellular amastigotes in both C2C12 myoblasts and bone marrow-derived macrophages. In myoblasts, the increased production of nitric oxide (NO) was essential for reduced parasite multiplication, whereas macrophage responses resulted in increased IL-6 and reduced TGF-β levels, indicating that parasite growth restriction mechanisms induced by IL-9 were cell-type specific. Experimental infection of BALB/c mice with T. cruzi trypomastigotes of the Y strain implicated a major role of IL-9 during the chronic phase, as increased Th9 and Tc9 cells were detected among splenocytes; higher levels of IL-9 in these cell populations and increased cardiac IL-9 levels were detected compared to those of uninfected mice. Moreover, rIL9 treatment decreased serum IL-12, IL-6, and IL-10 levels and cardiac TNF-α levels, possibly attempting to control the inflammatory response. IL-9 neutralization increased cardiac fibrosis, synthesis of collagens I and III, and mastocyte recruitment in BALB/c heart tissue during the chronic phase. In conclusion, our data showed that IL-9 reduced the invasion and multiplication of T. cruzi in vitro, in both myoblasts and macrophages, favoring disease control through cell-specific mechanisms. In vivo, IL-9 was elevated during experimental chronic infection in BALB/c mice, and this cytokine played a protective role in the immunopathological response during this phase by controlling cardiac fibrosis and proinflammatory cytokine production.

The multi-faceted roles of TGF-β in regulation of immunity to infection

Transforming Growth Factor-β is a potent regulator of the immune system, acting at every stage from thymic differentiation, population of the periphery, control of responsiveness, tissue repair and generation of memory. It is therefore a central player in the immune response to infectious pathogens, but its contribution is often clouded by multiple roles acting on different cells in time and space. Hence, context is all-important in understanding when TGF-β is beneficial or detrimental to the outcome of infection. In this review, a full range of infectious agents from viruses to helminth parasites are explored within this framework, drawing contrasts and general conclusions about the importance of TGF-β in these diseases.

Chromatic and Morphological Differentiation of Triatoma dimidiata (Hemiptera: Reduviidae) with Land Use Diversity in El Salvador

Chagas disease is caused by the parasite Trypanosoma cruzi, which is transmitted by insect-vectors in the taxonomic subfamily Triatominae and affects approximately 8,000,000 people world-wide. Current mitigation strategies for Chagas focus on insecticides, infrastructure improvements, and management of symptoms, which are largely unsustainable in underserved communities where the disease is widespread. Transmission patterns of vector-borne diseases are known to adaptively respond to habitat change; as such, the objective of our study was to evaluate how the physical characteristics of Triatoma dimidiata would vary in relation to land use in El Salvador. We hypothesized that the color and morphology of T. dimidiata would change with municipal levels of urban and natural green space, natural green space, and agricultural space, as well as municipal diversity, richness, and evenness of land use types. Our results characterize how T. dimidiata color and morphology vary directly with anthropogenic changes to natural and agricultural environments, which are reflective of a highly adaptable population primed to respond to environmental change. Mitigation studies of Chagas disease should exploit the relationships between anthropogenic land use and T. dimidiata morphology to evaluate how the transmission pattern of T. cruzi and Chagas disease symptomology are impacted.

Therapeutic miR-21 Silencing Reduces Cardiac Fibrosis and Modulates Inflammatory Response in Chronic Chagas Disease

Chagas disease, caused by the parasite Trypanosoma cruzi (T. cruzi), remains a serious public health problem for which there is no effective treatment in the chronic stage. Intense cardiac fibrosis and inflammation are hallmarks of chronic Chagas disease cardiomyopathy (CCC). Previously, we identified upregulation of circulating and cardiac miR-21, a pro-fibrotic microRNA (miRNA), in subjects with CCC. Here, we explored the potential role of miR-21 as a therapeutic target in a model of chronic Chagas disease. PCR array-based 88 microRNA screening was performed in heart samples obtained from C57Bl/6 mice chronically infected with T. cruzi and serum samples collected from CCC patients. MiR-21 was found upregulated in both human and mouse samples, which was corroborated by an in silico analysis of miRNA-mRNA target prediction. In vitro miR-21 functional assays (gain-and loss-of-function) were performed in cardiac fibroblasts, showing upregulation of miR-21 and collagen expression upon transforming growth factor beta 1 (TGFβ1) and T. cruzi stimulation, while miR-21 blockage reduced collagen expression. Finally, treatment of T. cruzi-infected mice with locked nucleic acid (LNA)-anti-miR-21 inhibitor promoted a significant reduction in cardiac fibrosis. Our data suggest that miR-21 is a mediator involved in the pathogenesis of cardiac fibrosis and indicates the pharmacological silencing of miR-21 as a potential therapeutic approach for CCC.

Effect of Posaconazole in an in vitro model of cardiac fibrosis induced by Trypanosoma cruzi

Posaconazole (POS) is an inhibitor of ergosterol biosynthesis in clinical use for treating invasive fungal infections. POS has potent and selective anti-Trypanosoma cruzi activity and has been evaluated as a possible treatment for Chagas disease. Microtissues are a 3D culture system that has been shown to reproduce better tissue architecture and functionality than cell cultures in monolayer (2D). It has been used to evaluate chemotropic response as in vitro disease models. We previously developed an in vitro model that reproduces aspects of cardiac fibrosis observed in Chagas cardiomyopathy, using microtissues formed by primary cardiac cells infected by the T. cruzi, here called T. cruzi fibrotic cardiac microtissue (TCFCM). We also showed that the treatment of TCFCM with a TGF-β pathway inhibitor reduces fibrosis. Here, we aimed to evaluate the effect of POS in TCFCM, observing parasite load and molecules involved in fibrosis. To choose the concentration of POS to be used in TCFCM we first performed experiments in a monolayer of primary cardiac cell cultures and, based on the results, TCFCM was treated with 5 nM of POS for 96 h, starting at 144 h post-infection. Our previous studies showed that at this time the TCFCM had established fibrosis, resulting from T. cruzi infection. Treatment with POS of TCFCM reduced 50 % of parasite load as observed by real-time PCR and reduced markedly the fibrosis as observed by western blot and immunofluorescence, associated with a strong reduction in the expression of fibronectin and laminin (45 % and 54 %, respectively). POS treatment also changed the expression of proteins involved in the regulation of extracellular matrix proteins (TGF-β and TIMP-4, increased by 50 % and decreased by 58 %, respectively) in TCFCM. In conclusion, POS presented a potent trypanocidal effect both in 2D and in TCFCM, and the reduction of the parasite load was associated with a reduction of fibrosis in the absence of external immunological effectors.

Tgfβ signaling is required for tenocyte recruitment and functional neonatal tendon regeneration

Tendon injuries are common with poor healing potential. The paucity of therapies for tendon injuries is due to our limited understanding of the cells and molecular pathways that drive tendon regeneration. Using a mouse model of neonatal tendon regeneration, we identified TGFβ signaling as a major molecular pathway that drives neonatal tendon regeneration. Through targeted gene deletion, small molecule inhibition, and lineage tracing, we elucidated TGFβ-dependent and TGFβ-independent mechanisms underlying tendon regeneration. Importantly, functional recovery depended on canonical TGFβ signaling and loss of function is due to impaired tenogenic cell recruitment from both Scleraxis-lineage and non-Scleraxis-lineage sources. We show that TGFβ signaling is directly required in neonatal tenocytes for recruitment and that TGFβ ligand is positively regulated in tendons. Collectively, these results show a functional role for canonical TGFβ signaling in tendon regeneration and offer new insights toward the divergent cellular activities that distinguish regenerative vs fibrotic healing.

Chagas' cardiomyopathy and Lyme carditis: Lessons learned from two infectious diseases affecting the heart

Chagas' disease and Lyme disease are two endemic, vector-borne zoonotic infectious diseases that impact multiple organ systems, including the heart. Chagas' cardiomyopathy is a progressive process that can evolve into a dilated cardiomyopathy and heart failure several decades after the acute infection; in contrast, although early-disseminated Lyme carditis has been relatively well characterized, the sequelae of Lyme disease on the heart are less well-defined. A century of research on Chagas' cardiomyopathy has generated compelling data for pathophysiological models, evaluated the efficacy of therapy in large randomized controlled trials, and explored the social determinants of health impacting preventative measures. Recognizing the commonalities between Chagas' disease and Lyme disease, we speculate on whether some of the lessons learned from Chagas' cardiomyopathy may be applicable to Lyme carditis.

Differential Role of TGF-β in Extracellular Matrix Regulation During Trypanosoma cruzi-Host Cell Interaction

Transforming growth factor beta (TGF-β) is a determinant for inflammation and fibrosis in cardiac and skeletal muscle in Chagas disease. To determine its regulatory mechanisms, we investigated the response of Trypanosoma cruzi-infected cardiomyocytes (CM), cardiac fibroblasts (CF), and L6E9 skeletal myoblasts to TGF-β. Cultures of CM, CF, and L6E9 were infected with T. cruzi (Y strain) and treated with TGF-β (1–10 ng/mL, 1 h or 48 h). Fibronectin (FN) distribution was analyzed by immunofluorescence and Western blot (WB). Phosphorylated SMAD2 (PS2), phospho-p38 (p-p38), and phospho-c-Jun (p-c-Jun) signaling were evaluated by WB. CF and L6E9 showed an increase in FN from 1 ng/mL of TGF-β, while CM displayed FN modulation only after 10 ng/mL treatment. CF and L6E9 showed higher PS2 levels than CM, while p38 was less stimulated in CF than CM and L6E9. T. cruzi infection resulted in localized FN disorganization in CF and L6E9. T. cruzi induced an increase in FN in CF cultures, mainly in uninfected cells. Infected CF cultures treated with TGF-β showed a reduction in PS2 and an increase in p-p38 and p-c-Jun levels. Our data suggest that p38 and c-Jun pathways may be participating in the fibrosis regulatory process mediated by TGF-β after T. cruzi infection.

TGF-β inhibitor therapy decreases fibrosis and stimulates cardiac improvement in a pre-clinical study of chronic Chagas' heart disease

TGF-β involvement in Chagas disease cardiomyopathy has been clearly demonstrated. The TGF-β signaling pathway is activated in the cardiac tissue of chronic phase patients and is associated with an increase in extracellular matrix protein expression. The aim of this study was to investigate the effect of GW788388, a selective inhibitor of TβR1/ALK5, on cardiac function in an experimental model of chronic Chagas' heart disease. To this end, C57BL/6 mice were infected with Trypanosoma cruzi (102 parasites from the Colombian strain) and treated orally with 3mg/kg GW788388 starting at 120 days post-infection (dpi), when 100% of the infected mice show cardiac damage, and following three distinct treatment schedules: i) single dose; ii) one dose per week; or iii) three doses per week during 30 days. The treatment with GW788388 improved several cardiac parameters: reduced the prolonged PR and QTc intervals, increased heart rate, and reversed sinus arrhythmia, and atrial and atrioventricular conduction disorders. At 180 dpi, 30 days after treatment interruption, the GW3x-treated group remained in a better cardiac functional condition. Further, GW788388 treatment reversed the loss of connexin-43 enriched intercellular plaques and reduced fibrosis of the cardiac tissue. Inhibition of the TGF-β signaling pathway reduced TGF-β/pSmad2/3, increased MMP-9 and Sca-1, reduced TIMP-1/TIMP-2/TIMP-4, and partially restored GATA-6 and Tbox-5 transcription, supporting cardiac recovery. Moreover, GW788388 administration did not modify cardiac parasite load during the infection but reduced the migration of CD3+ cells to the heart tissue. Altogether, our data suggested that the single dose schedule was not as effective as the others and treatment three times per week during 30 days seems to be the most effective strategy. The therapeutic effects of GW788388 are promising and suggest a new possibility to treat cardiac fibrosis in the chronic phase of Chagas' heart disease by TGF-β inhibitors.

Pathology and Pathogenesis of Chagas Heart Disease

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

Circulating Plasma MicroRNA-208a as Potential Biomarker of Chronic Indeterminate Phase of Chagas Disease

Chagas cardiomyopathy is the most severe clinical manifestation of chronic Chagas disease. The disease affects most of the Latin American countries, being considered one of the leading causes of morbidity and death in the continent. The pathogenesis of Chagas cardiomyopathy is very complex, with mechanisms involving parasite-dependent cytopathy, immune-mediated myocardial damage and neurogenic disturbances. These pathological changes eventually result in cardiac myocyte hypertrophy, arrhythmias, congestive heart failure and stroke during chronic infection phase. Herein, we show that miR-208a, a microRNA that is a key factor in promoting cardiovascular dysfunction during cardiac hypertrophy processes of heart failure, has its circulating levels increased during chronic indeterminate phase when compared to cardiac (CARD) clinical forms in patients with Chagas disease. In contrast, we have not found altered serum levels of miR-34a, a microRNA known to promote pro-apoptotic role in myocardial infarction during degenerative process of cardiac injuries thus indicating intrinsic differences in the nature of the mechanisms underlying the heart failure triggered by Trypanosoma cruzi infection. Our findings support that the chronic indeterminate phase is a progressive phase involved in the genesis of chagasic cardiopathy and point out the use of plasma levels of miR-208a as candidate biomarker in risk-prediction score for the clinical prognosis of Chagas disease.

Correlation of transforming growth factor-β1 and tumour necrosis factor levels with left ventricular function in Chagas disease

BACKGROUND

Transforming growth factor β1 (TGF-β1) and tumour necrosis factor (TNF) have been implicated in Chagas disease pathophysiology and may correlate with left ventricular (LV) function.

OBJECTIVES

We determined whether TGF-β1 and TNF serum levels correlate with LV systolic and diastolic functions and brain natriuretic peptide (BNP) serum levels in chronic Chagas disease.

METHODS

This cross-sectional study included 152 patients with Chagas disease (43% men; 57 ± 12 years old), classified as 53 patients with indeterminate form and 99 patients with cardiac form (stage A: 24, stage B: 25, stage C: 44, stage D: 6). TGF-β1, TNF, and BNP were determined by enzyme-linked immunosorbent assay ELISA. Echocardiogram was used to determine left atrial and LV diameters, as well as LV ejection fraction and diastolic function.

FINDINGS

TGF-b1 serum levels were lower in stages B, C, and D, while TNF serum levels were higher in stages C and D of the cardiac form. TGF-β1 presented a weak correlation with LV diastolic function and LV ejection fraction. TNF presented a weak correlation with left atrial and LV diameters and LV ejection fraction.

CONCLUSIONS

TNF is increased, while TGF-β1 is decreased in the cardiac form of chronic Chagas disease. TNF and TGF-β1 serum levels present a weak correlation with LV systolic and diastolic function in Chagas disease patients.

TGF-β Polymorphisms Are a Risk Factor for Chagas Disease

Transforming growth factor β1 (TGF-β1) is an important mediator in Chagas disease. Furthermore, patients with higher TGF-β1 serum levels show a worse clinical outcome. Gene polymorphism may account for differences in cytokine production during infectious diseases. We tested whether TGFB1 polymorphisms could be associated with Chagas disease susceptibility and severity in a Brazilian population. We investigated five single-nucleotide polymorphisms (-800 G>A, -509 C>T, +10 T>C, +25 G>C, and +263 C>T). 152 patients with Chagas disease (53 with the indeterminate form and 99 with the cardiac form) and 48 noninfected subjects were included. Genotypes CT and TT at position -509 of the TGFB1 gene were more frequent in Chagas disease patients than in noninfected subjects. Genotypes TC and CC at codon +10 of the TGFB1 gene were also more frequent in Chagas disease patients than in noninfected subjects. We found no significant differences in the distribution of the studied TGFB1 polymorphisms between patients with the indeterminate or cardiac form of Chagas disease. Therefore, -509 C>T and +10 T>C TGFB1 polymorphisms are associated with Chagas disease susceptibility in a Brazilian population.

Trypanosoma cruzi activates mouse cardiac fibroblasts in vitro leading to fibroblast-myofibroblast transition and increase in expression of extracellular matrix proteins

Background

Cardiac fibrosis is a consequence of chronic chagasic cardiomyopathy (CCC). In other cardiovascular diseases, the protagonist role of fibroblasts in cardiac fibrosis is well established. However, the role of cardiac fibroblasts (CFs) in fibrosis during the CCC is not clear. Here, our aim was to investigate the effect of Trypanosoma cruzi, the etiological agent of Chagas disease on CFs activation.

Methods

Cardiac fibroblasts were purified from primary cultures of mouse embryo cardiac cells. After two passages, cells were infected with T. cruzi (Y strain) and analyzed at different times for determination of infectivity, activation and production of extracellular matrix components (fibronectin, laminin and collagen IV) by immunofluorescence and western blot.

Results

At second passage, cultures were enriched in CFs (95% of fibroblasts and 5% of cardiomyocytes), as revealed by presence of alpha-smooth muscle actin (α-SMA) and discoidin domain receptor 2 (DDR2) and absence of sarcomeric tropomyosin (ST) protein expression. Trypanosoma cruzi infection induced fibroblast-myofibroblast transition, with increased expression of α-SMA after 6 and 24 h post-infection (hpi). Fibronectin was increased at 6, 24 and 48 hpi, laminin was increased at 6 and 24 hpi and collagen IV was increased at 6 hpi.

Conclusions

Our results showed that T. cruzi activates CFs, inducing activation and exacerbates ECM production. Furthermore, our data raise the possibility of the involvement of CFs in heart fibrosis during Chagas disease.

Inhibition of TGF-β pathway reverts extracellular matrix remodeling in T. cruzi-infected cardiac spheroids

Chagasic cardiomyopathy (CC) is the main manifestation of Chagas Disease (CD). CC is a progressive dysfunctional illness, in which transforming growth factor beta (TGF-β) plays a central role in fibrogenesis and hypertrophy. In the present study, we tested in a three-dimensional (3D) model of cardiac cells culture (named cardiac spheroids), capable of mimicking the aspects of fibrosis and hypertrophy observed in CC, the role of TGF-β pathway inhibition in restoring extracellular matrix (ECM) balance disrupted by T. cruzi infection. Treatment of T. cruzi-infected cardiac spheroids with SB 431542, a selective inhibitor of TGF-β type I receptor, resulted in a reduction in the size of spheroids, which was accompanied by a decrease in parasite load and in fibronectin expression. The inhibition of TGF-β pathway also promoted an increase in the activity of matrix metalloproteinase (MMP)-2 and a decrease in tissue inhibitor of matrix metalloproteinase (TIMP)-1 expression, which may be one of the mechanisms regulating extracellular matrix remodeling. Therefore, our study provides new insights into the molecular mechanisms by which inhibition of TGF-β signaling reverts fibrosis and hypertrophy generated by T. cruzi during CC and also highlights the use of cardiac spheroids as a valuable tool for the study of fibrogenesis and anti-fibrotic compounds.

Chronic Chagas Heart Disease Management: From Etiology to Cardiomyopathy Treatment

Trypanosoma cruzi (T. cruzi) infection is endemic in Latin America and is becoming a worldwide health burden. It may lead to heterogeneous phenotypes. Early diagnosis of T. cruzi infection is crucial. Several biomarkers have been reported in Chagas heart disease (ChHD), but most are nonspecific for T. cruzi infection. Prognosis of ChHD patients is worse compared with other etiologies, with sudden cardiac death as an important mode of death. Most ChHD patients display diffuse myocarditis with fibrosis and hypertrophy. The remodeling process seems to be associated with etiopathogenic mechanisms and neurohormonal activation. Pharmacological treatment and antiarrhythmic therapy for ChHD is mostly based on results for other etiologies. Heart transplantation is an established, valuable therapeutic option in refractory ChHD. Implantable cardioverter-defibrillators are indicated for prevention of secondary sudden cardiac death. Specific etiological treatments should be revisited and reserved for select patients. Understanding and management of ChHD need improvement, including development of randomized trials.

Thrombospondin-4 mediates TGF-β-induced angiogenesis

TGF-β is a multifunctional cytokine affecting many cell types and implicated in tissue remodeling processes. Due to its many functions and cell-specific effects, the consequences of TGF-β signaling are process-and stage-dependent, and it is not uncommon that TGF-β exerts distinct and sometimes opposing effects on a disease progression depending on the stage and on the pathological changes associated with the stage. The mechanisms underlying cell- and process-specific effects of TGF-β are poorly understood.

We are describing a novel pathway that mediates induction of angiogenesis in response to TGF-β1. We found that in endothelial cells (EC) TSP-4, a secreted extracellular matrix (ECM) protein is upregulated in response to TGF-β1 and mediates the effects of TGF-β1 on angiogenesis.

Upregulation of TSP-4 does not require the synthesis of new protein, is not caused by decreased secretion of TSP-4, and is mediated by activation of SMAD3. Using Thbs4^−/− mice and TSP-4 shRNA, we found that TSP-4 mediated pro-angiogenic functions on cultured EC and angiogenesis in vivo in response to TGF-β1. We observed ~ 3-fold increases in tumor mass and levels of angiogenesis markers in animals injected with TGF-β1, and these effects did not occur in Thbs4^−/− animals. Injections of an inhibitor of TGF-β1 signaling SB431542 also decreased the weights of tumors and cancer angiogenesis.

Our results from in vivo angiogenesis models and cultured EC document that TSP-4 mediates upregulation of angiogenesis by TGF-β1. Upregulation of pro-angiogenic TSP-4 and selective effects of TSP-4 on EC may contribute to stimulation of tumor growth by TGF-β despite the inhibition of cancer cell proliferation.

Differential cytokine profiling in Chagasic patients according to their arrhythmogenic-status

Background

Chagas disease is caused by the protozoan Trypanosoma cruzi and is characterized by heart failure and sudden death. Identifying which factors are involved in evolution and treatment response is actually challenging.

Thus, the aim of this work was to determine the Th1/Th17 (IL-6, IL-2, TNF, IL-17 and IFN-γ) and Th2 (IL-4 and IL-10) serum profile in Venezuelan Chagasic patients stratified according amiodarone treatment, hypertension and arrhythmias.

Methods

Sera from 38 chagasic patients were analyzed to determine the level of cytokines by Multiplexed Bead-Based Immunoassays. ANOVA test was applied to determine differences for each group. Additionally, a Linear Discriminant Analysis (LDA) was applied to observe the accuracy of different cytokines to discriminate between the groups.

Results

The levels of several cytokines were significantly higher in the high-risk of sudden death and untreated group. LDA showed that IL-2, IFN-γ and IL-10 were the best cytokines for discriminating between high-risk of sudden death and untreated patients versus low-risk of sudden death, treated and control groups.

Conclusions

High IL-2 levels seem to identify patients with high-risk of sudden death and seems adequate as treatment efficacy marker. To our knowledge, this is the first report about the anti-inflammatory role of the amiodarone in Chagas disease, suggesting an inmunomodulatory effect that may be exploited as coadjutant therapy in chronic Chagas disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2324-x) contains supplementary material, which is available to authorized users.

Trypanosoma cruzi High Mobility Group B (TcHMGB) can act as an inflammatory mediator on mammalian cells

Background

High Mobility Group B (HMGB) proteins are nuclear architectural factors involved in chromatin remodeling and important nuclear events. HMGBs also play key roles outside the cell acting as alarmins or Damage-associated Molecular Patterns (DAMPs). In response to a danger signal these proteins act as immune mediators in the extracellular milieu. Moreover, these molecules play a central role in the pathogenesis of many autoimmune and both infectious and sterile inflammatory chronic diseases.

Principal findings

We have previously identified a High mobility group B protein from Trypanosoma cruzi (TcHMGB) and showed that it has architectural properties interacting with DNA like HMGBs from other eukaryotes. Here we show that TcHMGB can be translocated to the cytoplasm and secreted out of the parasite, a process that seems to be stimulated by acetylation. We report that recombinant TcHMGB is able to induce an inflammatory response in vitro and in vivo, evidenced by the production of Nitric Oxide and induction of inflammatory cytokines like TNF-α, IL-1β and IFN-γ gene expression. Also, TGF-β and IL-10, which are not inflammatory cytokines but do play key roles in Chagas disease, were induced by rTcHMGB.

Conclusions

These preliminary results suggest that TcHMGB can act as an exogenous immune mediator that may be important for both the control of parasite replication as the pathogenesis of Chagas disease and can be envisioned as a pathogen associated molecular pattern (PAMP) partially overlapping in function with the host DAMPs.

When an infection occurs, the innate immune cells recognize Pathogen Associated Molecular Patterns (PAMPs) through their Pattern Recognition Receptors. This triggers an inflammatory response intended to kill the foreign microbe. But inflammation can also be triggered by the recognition of endogenous molecules called “Danger (or Damage) Associated Molecular Patterns” (DAMPs) that are released by damaged or necrotic cells to “ring the alarm” of the immune system that repair is needed, so some of them are also known as “alarmins”. High Mobility group box 1 protein (HMGB1) is a prototypical alarmin molecule released by injured cells and it is also actively secreted by cells of the innate immune system in response to invasion as well as to sterile damage. Trypanosoma cruzi, the causal agent of Chagas Disease, has its own HMGB protein that we called TcHMGB. Using in vitro and in vivo experimental systems, we demonstrated for the first time that TcHMGB is able to mediate inflammation on mammalian cells, inducing the expression of both pro-inflammatory and anti-inflammatory cytokines. Our results suggest that the parasite´s protein could have a role in the immune response and the pathogenesis of Chagas disease, probably overlapping to some extent with the host cell DAMP molecules´ functions.

Scrutinizing the Biomarkers for the Neglected Chagas Disease: How Remarkable!

Biomarkers or biosignature profiles have become accessible over time in population-based studies for Chagas disease. Thus, the identification of consistent and reliable indicators of the diagnosis and prognosis of patients with heart failure might facilitate the prioritization of therapeutic management to those with the highest chance of contracting this disease. The purpose of this paper is to review the recent state and the upcoming trends in biomarkers for human Chagas disease. As an emerging concept, we propose a classification of biomarkers based on plasmatic-, phenotype-, antigenic-, genetic-, and management-related candidates. The available data revisited here reveal the lessons learned thus far and the existing challenges that still lie ahead to enable biomarkers to be employed consistently in risk evaluation for this disease. There is a strong need for biomarker validation, particularly for biomarkers that are specific to the clinical forms of Chagas disease. The current failure to achieve the eradication of the transmission of this disease has produced determination to solve this validation issue. Finally, it would be strategic to develop a wide variety of biomarkers and to test them in both preclinical and clinical trials.

TGF-β receptor type II costameric localization in cardiomyocytes and host cell TGF-β response is disrupted by Trypanosoma cruzi infection

Transforming growth factor beta (TGF-β) cytokine is involved in Chagas disease establishment and progression. Since Trypanosoma cruzi can modulate host cell receptors, we analysed the TGF-β receptor type II (TβRII) expression and distribution during T. cruzi – cardiomyocyte interaction. TβRII immunofluorescent staining revealed a striated organization in cardiomyocytes, which was co-localized with vinculin costameres and enhanced (38%) after TGF-β treatment. Cytochalasin D induced a decrease of 45·3% in the ratio of cardiomyocytes presenting TβRII striations, demonstrating an association of TβRII with the cytoskeleton. Western blot analysis showed that cytochalasin D significantly inhibited Smad 2 phosphorylation and fibronectin stimulation after TGF-β treatment in cardiomyocytes. Trypanosoma cruzi infection elicited a decrease of 79·8% in the frequency of cardiomyocytes presenting TβRII striations, but did not interfere significantly in its expression. In addition, T. cruzi-infected cardiomyocytes present a lower response to exogenous TGF-β, showing no enhancement of TβRII striations and a reduction of phosphorylated Smad 2, with no significant difference in TβRII expression when compared to uninfected cells. Together, these results suggest that the co-localization of TβRII with costameres is important in activating the TGF-β signalling cascade, and that T. cruzi-derived cytoskeleton disorganization could result in altered or low TGF-β response in infected cardiomyocytes.

Developments in the management of Chagas cardiomyopathy

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

Cruzipain Activates Latent TGF-β from Host Cells during T. cruzi Invasion

Several studies indicate that the activity of cruzipain, the main lysosomal cysteine peptidase of Trypanosoma cruzi, contributes to parasite infectivity. In addition, the parasitic invasion process of mammalian host cells is described to be dependent on the activation of the host TGF-β signaling pathway by T. cruzi. Here, we tested the hypothesis that cruzipain could be an important activator of latent TGF-β and thereby trigger TGF-β-mediated events crucial for the development of Chagas disease. We found that live epimastigotes of T. cruzi, parasite lysates and purified cruzipain were able to activate latent TGF-β in vitro. This activation could be inhibited by the cysteine peptidase inhibitor Z-Phe-Ala-FMK. Moreover, transfected parasites overexpressing chagasin, a potent endogenous cruzipain inhibitor, prevented latent TGF-β activation. We also observed that T. cruzi invasion, as well as parasite intracellular growth, were inhibited by the administration of Z-Phe-Ala-FMK or anti-TGF-β neutralizing antibody to Vero cell cultures. We further demonstrated that addition of purified cruzipain enhanced the invasive activity of trypomastigotes and that this effect could be completely inhibited by addition of a neutralizing anti-TGF-β antibody. Taken together, these results demonstrate that the activities of cruzipain and TGF-β in the process of cell invasion are functionally linked. Our data suggest that cruzipain inhibition is an interesting chemotherapeutic approach for Chagas disease not only because of its trypanocidal activity, but also due to the inhibitory effect on TGF-β activation.

Neuroprotective effects of SMADs in a rat model of cerebral ischemia/reperfusion

Previous studies have shown that up-regulation of transforming growth factor β1 results in neuroprotective effects. However, the role of the transforming growth factor β1 downstream molecule, SMAD2/3, following ischemia/reperfusion remains unclear. Here, we investigated the neuroprotective effects of SMAD2/3 by analyzing the relationships between SMAD2/3 expression and cell apoptosis and inflammation in the brain of a rat model of cerebral ischemia/reperfusion. Levels of SMAD2/3 mRNA were up-regulated in the ischemic penumbra 6 hours after cerebral ischemia/reperfusion, reached a peak after 72 hours and were then decreased at 7 days. Phosphorylated SMAD2/3 protein levels at the aforementioned time points were consistent with the mRNA levels. Over-expression of SMAD3 in the brains of the ischemia/reperfusion model rats via delivery of an adeno-associated virus containing the SMAD3 gene could reduce tumor necrosis factor-α and interleukin-1β mRNA levels, down-regulate expression of the pro-apoptotic gene, capase-3, and up-regulate expression of the anti-apoptotic protein, Bcl-2. The SMAD3 protein level was negatively correlated with cell apoptosis. These findings indicate that SMAD3 exhibits neuroprotective effects on the brain after ischemia/reperfusion through anti-inflammatory and anti-apoptotic pathways.

Emerging and reemerging neglected tropical diseases: a review of key characteristics, risk factors, and the policy and innovation environment

In global health, critical challenges have arisen from infectious diseases, including the emergence and reemergence of old and new infectious diseases. Emergence and reemergence are accelerated by rapid human development, including numerous changes in demographics, populations, and the environment. This has also led to zoonoses in the changing human-animal ecosystem, which are impacted by a growing globalized society where pathogens do not recognize geopolitical borders. Within this context, neglected tropical infectious diseases have historically lacked adequate attention in international public health efforts, leading to insufficient prevention and treatment options. This subset of 17 infectious tropical diseases disproportionately impacts the world's poorest, represents a significant and underappreciated global disease burden, and is a major barrier to development efforts to alleviate poverty and improve human health. Neglected tropical diseases that are also categorized as emerging or reemerging infectious diseases are an even more serious threat and have not been adequately examined or discussed in terms of their unique risk characteristics. This review sets out to identify emerging and reemerging neglected tropical diseases and explore the policy and innovation environment that could hamper or enable control efforts. Through this examination, we hope to raise awareness and guide potential approaches to addressing this global health concern.

Dab2 attenuates brain injury in APP/PS1 mice via targeting transforming growth factor-beta/SMAD signaling

Transforming growth factor-beta (TGF-β) type II receptor (TβRII) levels are extremely low in the brain tissue of patients with Alzheimer's disease. This receptor inhibits TGF-β1/SMAD signaling and thereby aggravates amyolid-beta deposition and neuronal injury. Dab2, a specific adapter protein, protects TβRII from degradation and ensures the effective conduction of TGF-β1/SMAD signaling. In this study, we used an adenoviral vector to overexpress the Dab2 gene in the mouse hippocampus and investigated the regulatory effect of Dab2 protein on TGF-β1/SMAD signaling in a mouse model of Alzheimer's disease, and the potential neuroprotective effect. The results showed that the TβRII level was lower in APP/PS1 mouse hippocampus than in normal mouse hippocampus. After Dab2 expression, hippocampal TβRII and p-SMAD2/3 levels were significantly increased, while amyloid-beta deposition, microglia activation, tumor necrosis factor-α and interleulin-6 levels and neuronal loss were significantly attenuated in APP/PS1 mouse brain tissue. These results suggest that Dab2 can exhibit neuroprotective effects in Alzheimer's disease by regulating TGF-β1/SMAD signaling.

Interrelationship among muscle, fat, and bone: connecting the dots on cellular, hormonal, and whole body levels

While sarcopenia and sarcopenic obesity have been recognized in the last decade, a combined concept to include decreased muscle mass and strength, as well as decreased bone mass with coexistence of adiposity is discussed here. We introduce a new term, osteopenic obesity, and operationalize its meaning within the context of osteopenia and obesity. Next, we consolidate osteopenic obesity with the already existing and more familiar term, sarcopenic obesity, and delineate the resulting combined condition assigning it the term osteosarcopenic obesity. Identification and possible diagnosis of each condition are discussed, as well as the interactions of muscle, fat and bone tissues on cellular level, considering their endocrine features. Special emphasis is placed on the mesenchymal stem cell commitment into osteoblastogenic, adipogenic and myogenic lineages and causes of its deregulation. Based on the presented evidence and as expounded within the text, it is reasonable to say that under certain conditions, osteoporosis and sarcopenia could be the obesity of bone and muscle, respectively, with the term osteosarcopenic obesity as an encompassment for all.

DTU I isolates of Trypanosoma cruzi induce upregulation of Galectin-3 in murine myocarditis and fibrosis

Chagas heart disease is a major public concern since 30% of infected patients develop cardiac alterations. The relationship between Trypanosoma cruzi discrete typing units (DTUs) and the biological properties exhibited by the parasite population has yet to be elucidated. In this study, we analysed the expression of α-smooth muscle actin (α-SMA) and galectin-3 (Gal-3) associated with cardiac extracellular matrix (ECM) remodelling a murine chronic cardiomyopathy induced by Tc I genotypes. We found the induction of myocarditis was associated with the upregulation of Col I, α-SMA, Gal-3, IFN-γ and IL-13, as analysed by q-PCR. In myocardial areas of fibrosis, the intensity of myocarditis and significant ECM remodelling correlated with the presence of Col I-, Gal-3- and α-SMA-positive cells. These results are promising for the further efforts to evaluate the relevance of Gal-3 in Chagas heart disease, since this galectin was proposed as a prognosis marker in heart failure patients.

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.

Predictive value of transforming growth factor-β1in Chagas disease: towards a biomarker surrogate of clinical outcome

BACKGROUND

Transforming growth factor-β1 (TGF-β1) may be implicated in the development of Chagas heart disease. However, the clinical value of TGF-β1 measurement is yet to be determined.

METHODS

We retrospectively analyzed the outcome of 54 Chagas disease patients without heart failure and with left ventricular (LV) ejection fraction >45% whose TGF-β1 serum values were determined between January 1998 and December 1999. Primary end point was all-cause mortality and secondary end point was the combination of all-cause mortality or hospitalization due to worsening heart failure or cardiac arrhythmias.

RESULTS

TGF-β1 was independently associated with the occurrence of the primary and secondary end points. The optimal cutoff for TGF-β1 to identify the primary end point was 12.9 ng/ml (area under the curve = 0.82, p = 0.004, sensitivity 100%, and specificity 57%) and to identify the secondary end point was 30.8 ng/ml (area under the curve = 0.72, p = 0.03, sensitivity 60%, and specificity 86%). LV ejection fraction and LV end-diastolic diameter were also independent predictors of the primary and secondary endpoints, respectively.

CONCLUSION

The described association between TGF-β1 and clinical outcome provides evidence towards the clinical value of TGF-β1 in Chagas disease.

Trypanosoma cruzi highjacks TrkC to enter cardiomyocytes and cardiac fibroblasts while exploiting TrkA for cardioprotection against oxidative stress

Chronic Chagas cardiomyopathy (CCC), caused by the obligate intracellular protozoan parasite Trypanosoma cruzi, is a major cause of morbidity and mortality in Latin America. CCC begins when T. cruzi enters cardiac cells for intracellular multiplication and differentiation, a process that starts with recognition of host-cell entry receptors. However, the nature of these surface molecules and corresponding parasite counter-receptor(s) is poorly understood. Here we show that antibodies against neurotrophin (NT) receptor TrkC, but not against family members TrkA and TrkB, prevent T. cruzi from invading primary cultures of cardiomyocytes and cardiac fibroblasts. Invasion is also selectively blocked by the TrkC ligand NT-3, and by antagonists of Trk autophosphorylation and downstream signalling. Therefore, these results indicate that T. cruzi gets inside cardiomyocytes and cardiac fibroblasts by activating TrkC preferentially over TrkA. Accordingly, short hairpin RNA interference of TrkC (shTrkC), but not TrkA, selectively prevents T. cruzi from entering cardiac cells. Additionally, T. cruzi parasite-derived neurotrophic factor (PDNF)/trans-sialidase, a TrkC-binding protein, but not family member gp85, blocks entry dose-dependently, underscoring the specificity of PDNF as TrkC counter-receptor in cardiac cell invasion. In contrast to invasion, competitive and shRNA inhibition studies demonstrate that T. cruzi-PDNF recognition of TrkA, but not TrkC on primary cardiomyocytes and the cardiomyocyte cell line H9c2 protects the cells against oxidative stress. Thus, this study shows that T. cruzi via PDNF favours neurotrophin receptor TrkC for cardiac cell entry and TrkA for cardiomyocyte protection against oxidative stress, and suggests a new therapeutic opportunity in PDNF and/or fragments thereof for CCC therapy as entry inhibitors and/or cardioprotection agonists.