DNA damage and oxidative stress in human cells infected by Trypanosoma cruzi

Antioxidant and anti-glycation activities of Mandevilla velutina extract and effect on parasitemia levels in Trypanosoma cruzi experimental infection: In vivo, in vitro and in silico approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Mandevilla velutina (Mart. Ex Stadelm.) Woodson, known in Brazil as "infalível" and "jalapa", is a medicinal plant native from the Cerrado region (Brazilian Savannah). The underground organ (xylopodium) of this species is prepared as ethanolic extract or infusion and it is commonly used in traditional medicine to treat snake venom. Although, locals and indigenous populations from Cerrado have used M. velutina for the treatment of infection by Trypanosoma cruzi (Chagas' disease).

AIM OF THE STUDY

This study aimed to evaluate the in vitro antioxidant and anti-glycation activities of the crude hydroethanolic extract of M. velutina xylopodium. Besides, it aimed to evaluate its effect on parasitemia levels in vivo T. cruzi experimental infection. In addition, this study aimed to determine possible interactions between the main compound of the extract and molecular targets associated with survival and virulence of T. cruzi in silico approaches.

MATERIALS AND METHODS

Determination of total polyphenols, flavonoids and steroidal aglycones content were performed. In addition, high performance liquid chromatography (HPLC) was carried out to identify main compounds of the extract. Antioxidant activity was determined by DPPH radical scavenging, ferric ion reducing power (FRAP), Thiobarbituric acid reactive species (TBARS) and Oxygen Radical Absorbance Capacity (ORAC) methods. Anti-glycation activity was demonstrated through relative mobility in electrophoresis (RME), determination of free amino groups and inhibition of AGEs formation. Determination of the action of extract in parasitemia levels was performed by T. cruzi experimental infection of mice and nitrite levels were measured in the serum of animals evaluated in this study. Molecular docking analyses of the main compound (Velutinol A) with DNA and molecular targets associated with survival and virulence of T. cruzi.

RESULTS

Phytoconstituents evaluation exhibited the presence polyphenols, flavonoids and steroidal aglycone, and HPLC identified the major presence of Velutinol A. Antioxidant and anti-glycation evaluations showed that the extract present significant activity in all methods evaluated. In addition, extract reduced the number of trypomastigotes and increased the survival of treated animals. The treatment using extract showed an interference in the synthesis of physiological nitric oxide as an immune response to infection. In silico assays demonstrated interaction between Velutinol A and DNA and molecular targets of T. cruzi.

CONCLUSIONS

The results showed that the hydroethanolic extract of M. velutina xylopodium contains bioactive compounds including polyphenols, flavonoids and steroidal aglycones (mainly Velutinol A) of which may be responsible for the antioxidant, anti-glycation and anti-parasitic activity against T. cruzi. Trypanocidal activity of M. velutina compounds may be linked to their influence on NO synthesis during infection and/or their capacity to bind and inhibit molecules associated to virulence and survival of T. cruzi.

The role of Nrf2 signaling in parasitic diseases and its therapeutic potential

In response to invading parasites, one of the principal arms of innate immunity is oxidative stress, caused by reactive oxygen species (ROS). However, oxidative stresses play dual functions in the disease, whereby free radicals promote pathogen removal, but they can also trigger inflammation, resulting in tissue injuries. A growing body of evidence has strongly supported the notion that nuclear factor erythroid 2-related factor 2 (NRF) signaling is one of the main antioxidant pathways to combat this oxidative burst against parasites. Given the important role of NRF2 in oxidative stress, in this review, we investigate the activation mechanism of the NRF2 antioxidant pathway in different parasitic diseases, such as malaria, leishmaniasis, trypanosomiasis, toxoplasmosis, schistosomiasis, entamoebiasis, and trichinosis.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

BACKGROUND

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

METHODOLOGY

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/ 5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

RESULTS

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

CONCLUSIONS

These data confirm toxicity associated with curative doses of BNZ and suggest that while dose sparing low BNZ plus vaccine treatment does not reduce parasite burdens, it better preserves liver health.

Immunologic changes are detectable in the peripheral blood transcriptome of clinically asymptomatic Chagas cardiomyopathy patients

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is a neglected parasitic disease that affects approximately 6 million individuals worldwide. Of those infected, 20-30% will go on to develop chronic Chagas cardiomyopathy (CCC), and ultimately many of these individuals will progress to advanced heart failure. The mechanism by which this progression occurs is poorly understood, as few studies have focused on early CCC. In this study, we sought to understand the physiologic changes associated with T. cruzi infection and the development of CCC. We analyzed gene expression in the peripheral blood of asymptomatic Chagas patients with early structural heart disease, Chagas patients without any signs or symptoms of disease, and Chagas-negative patients with and without early structural heart disease. Our analysis shows that early CCC was associated with a downregulation of various peripheral immune response genes, with gene expression changes suggestive of reduced antigen presentation and T cell activation. Notably, these genes and processes were distinct from those of early cardiomyopathy in Chagas-negative patients, suggesting that the processes mediating CCC may be unique from those mediating progression to other cardiomyopathies. This work highlights the importance of the immune response in early CCC, providing insight into the early pathogenesis of this disease. The changes we have identified may serve as biomarkers of progression and could inform strategies for the treatment of CCC in its early stages, before significant cardiac damage has occurred.

"Slow kill" treatment reduces DNA damage in leukocytes of dogs naturally infected with Dirofilaria immitis

Parasitic diseases are considered to be a cause of oxidative stress which leads to oxidative damage of various molecules including DNA. This can result in mutations, replication errors, and genome instability. Therefore, aim of this study was to measure DNA damage induced by Dirofilaria immitis in the single cells such as dogs' leukocytes using the comet assay. Also, we monitored the effects of antiparasitic treatment on mitigation of sensitivity to DNA damage in leukocytes treated with H2O2 using the in vivo and ex vivo comet assay. The whole blood samples from 34 dogs from Serbia were used, both males and females, from one to 13 years old, both pure and mixed-breeds. A rapid immunochromatographic test (Antigen Rapid Heartworm Ag 2.0 Test Kit, Bionote, Minnesota, USA) was used for the detection of D. immitis antigens. The modified Knott's test and PCR were used in the aim of detecting D. immitis microfilariae in dogs' blood, and evaluating the number of circulating microfilariae during the treatment. The genotoxicity evaluation showed that D. immitis infection resulted in DNA damage in naturally infected dogs, with the highest DNA damage occurring in the group of dogs with severe clinical signs. Treatment with ivermectin and doxycycline decreased DNA damage in leukocytes of dogs in all groups, as the intensity of infection decreased due to applied therapy. Ex vivo comet assay results showed that leukocytes exhibited decreased sensitivity to H2O2-induced DNA damage during treatment. The results of the modified Knott's test and PCR in our study showed that treatment with ivermectin and doxycycline was successful in decreasing the average number of microfilariae during the time and at the end eliminating them from the dogs' blood.

PARPs and ADP-Ribosylation in Chronic Inflammation: A Focus on Macrophages

Aberrant adenosine diphosphate-ribose (ADP)-ribosylation of proteins and nucleic acids is associated with multiple disease processes such as infections and chronic inflammatory diseases. The poly(ADP-ribose) polymerase (PARP)/ADP-ribosyltransferase (ART) family members promote mono- or poly-ADP-ribosylation. Although evidence has linked PARPs/ARTs and macrophages in the context of chronic inflammation, the underlying mechanisms remain incompletely understood. This review provides an overview of literature focusing on the roles of PARP1/ARTD1, PARP7/ARTD14, PARP9/ARTD9, and PARP14/ARTD8 in macrophages. PARPs/ARTs regulate changes in macrophages during chronic inflammatory processes not only via catalytic modifications but also via non-catalytic mechanisms. Untangling complex mechanisms, by which PARPs/ARTs modulate macrophage phenotype, and providing molecular bases for the development of new therapeutics require the development and implementation of innovative technologies.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

Background

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

Methodology

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

Results

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

Conclusions

These data confirm toxicity associated with curative doses of BNZ and suggest that the dose sparing low BNZ plus vaccine treatment better preserves liver health.

Pharmacological potential of new metronidazole/eugenol/dihydroeugenol hybrids against Trypanosoma cruzi in vitro and in vivo

AIMS

From well-delimited immunomodulatory, redox and antimicrobial properties; metronidazole and eugenol were used as structural platforms to assembly two new molecular hybrids (AD06 and AD07), whose therapeutic relevance was analyzed on T. cruzi infection in vitro and in vivo.

METHODS

Non-infected, T. cruzi-infected H9c2 cardiomyocytes, and mice non-treated and treated with vehicle, benznidazole (Bz - reference drug), AD06 and AD07 were investigated. Parasitological, prooxidant, antioxidant, microstructural, immunological, and hepatic function markers were analyzed.

RESULTS

Our findings indicated that in addition to having a direct antiparasitic effect on T. cruzi, metronidazole/eugenol hybrids (especially AD07) attenuated cellular parasitism, reactive species biosynthesis and oxidative stress in infected cardiomyocytes in vitro. Although AD06 and AD07 exerted no relevant impact on antioxidant enzymes activity (CAT, SOD, GR and GPx) in host cells, these drugs (especially AD07) attenuated trypanothione reductase activity in T. cruzi, which increased parasite's susceptibility to in vitro pro-oxidant challenge. AD06 and AD07 were well tolerated and do not determine humoral response suppression, mortality (100 % survival) or hepatotoxicity in mice, as indicated by transaminases plasma levels. AD07 also induced relevant in vivo antiparasitic and cardioprotective effects, attenuating parasitemia, cardiac parasite load and myocarditis in T. cruzi-infected mice. Although this cardioprotective response is potentially related to AD07 antiparasitic effect, a direct anti-inflammatory potential of this molecular hybrid cannot be ruled out.

CONCLUSION

Taken together, our findings indicated that the new molecular hybrid AD07 stood out as a potentially relevant candidate for the development of new, safe and more effective drug regimens for T. cruzi infection treatment.

Oxidative stress, cardiomyocytes senescence and contractile dysfunction in in vitro and in vivo experimental models of Chagas disease

AIMS

The relationship between redox imbalance and cardiovascular senescence in infectious myocarditis is unknown. Thus, the aim of this study was to investigate whether cardiomyocytes parasitism, oxidative stress and contractile dysfunction can be correlated to senescence-associated β-galactosidase (SA-β-Gal) activity in Trypanosoma cruzi-infection in vitro and in vivo.

METHODS

Uninfected, T. cruzi-infected untreated and benznidazole (BZN)-treated H9c2 cardiomyocytes and rats were investigated. Parasitological, prooxidant, antioxidant, microstructural, and senescence-associated markers were quantified in vitro and in vivo.

RESULTS

T. cruzi infection triggered intense cardiomyocytes parasitism in vitro and in vivo, which was accompanied by reactive oxygen species (ROS) upregulation, lipids, proteins and DNA oxidation in cardiomyocytes and cardiac tissue. Oxidative stress was parallel to microstructural cell damage (e.g., increased cardiac toponin I levels) and contractile dysfunction in cardiomyocytes in vitro and in vivo, whose severity accompanied a premature cellular senescence-like phenotype revealed by increased senescence-associated β-galactosidase (SA-β-Gal) activity and DNA oxidation (8-OHdG). Cellular parasitism (e.g., infection rate and parasite load), myocarditis and T. cruzi-induced prooxidant responses were attenuated by early BZN administration to interrupt the progression of T. cruzi infection, protecting against SA-β-gal-based premature cellular senescence, microstructural damage and contractile deterioration in cardiomyocytes from T. cruzi-infected animals.

CONCLUSION

Our findings indicated that cell parasitism, redox imbalance and contractile dysfunction were correlated to SA-β-Gal-based cardiomyocytes premature senescence in acute T. cruzi infection. Therefore, in addition to controlling parasitism, inflammation and oxidative stress; inhibiting cardiomyocytes premature senescence should be further investigated as an additional target of specific Chagas disease therapeutics.

Trypanosoma cruzi infection changes the chromatin proteome profile of infected human cells

Chagas disease is endemic in 22 Latin American countries, with approximately 8 million individuals infected worldwide and 10,000 deaths yearly. Trypanosoma cruzi presents an intracellular life cycle in mammalian hosts to sustain infection. Parasite infection activates host cell responses, promoting an unbalance in reactive oxygen species (ROS) in the intracellular environment inducing genomic DNA lesions in the host cell during infection. To further understand changes in host cell chromatin induced by parasite infection, we investigated alterations in chromatin caused by infection by performing quantitative proteomic analysis. DNA Damage Repair proteins, such as Poly-ADP-ribose Polymerase 1 (PARP-1) and X-Ray Repair Cross Complementing 6 (XRRC6), were recruited to the chromatin during infection. Also, changes in chromatin remodeling enzymes suggest that parasite infection may shape the epigenome of the host cells. Interestingly, the abundance of oxidative phosphorylation mitochondrial and vesicle-mediated transport proteins increased in the host chromatin at the final stages of infection. In addition, Apoptosis-inducing Factor (AIF) is translocated to the host cell nucleus upon infection, suggesting that cells enter parthanatos type of death. Altogether, this study reveals how parasites interfere with the host cells' responses at the chromatin level leading to significant crosstalk that support and disseminate infection. SIGNIFICANCE: The present study provides novel insights into the effects of Trypanosoma cruzi on the chromatin from the host cell. This manuscript investigated proteomic alterations in chromatin caused by parasite infection at early and late infection phases by performing a quantitative proteomic analysis. In this study, we revealed that parasites interfere with DNA metabolism in the early and late stages of infection. We identified that proteins related to DNA damage repair, oxidative phosphorylation, and vesicle-mediated transport have increased abundance at the host chromatin. Additionally, we have observed that Apoptosis-inducing Factor is translocated to the host cell nucleus upon infection, suggesting that the parasites could lead the cells to enter Parthanatos as a form of programmed cell death. The findings improve our understanding on how the parasites modulate the host cell chromatin to disseminate infection. In this study, we suggest a mechanistic parasite action towards host nucleus that could be used to indicate targets for future treatments.

Genetic Instability among Hitnü People Living in Colombian Crude-Oil Exploitation Areas

Oil exploitation, drilling, transportation, and processing in refineries produces a complex mixture of chemical compounds, including polycyclic aromatic hydrocarbons (PAHs), which may affect the health of populations living in the zone of influence of mining activities (PZOI). Thus, to better understand the effects of oil exploitation activities on cytogenetic endpoint frequency, we conducted a biomonitoring study in the Hitnü indigenous populations from eastern Colombia by using the cytokinesis micronucleus cytome assay (CBMN-cyt). PAH exposure was also measured by determine urine 1-hydroxypyrene (1-OHP) using HPLC. We also evaluated the relationship between DNA damage and 1-OHP levels in the oil exploitation area, as well as the modulating effects of community health factors, such as Chagas infection; nutritional status; and consumption of traditional hallucinogens, tobacco, and wine from traditional palms. The frequencies of the CBMN-cyt assay parameters were comparable between PZOI and Hitnü populations outside the zone of influence of mining activities (POZOI); however, a non-significant incremental trend among individuals from the PZOI for most of the DNA damage parameters was also observed. In agreement with these observations, levels of 1-OHP were also identified as a risk factor for increased MN frequency (PR = 1.20) compared to POZOI (PR = 0.7). Proximity to oil exploitation areas also constituted a risk factor for elevated frequencies of nucleoplasmic bridges (NPBs) and APOP-type cell death. Our results suggest that genetic instability and its potential effects among Hitnü individuals from PZOI and POZOI could be modulated by the combination of multiple factors, including the levels of 1-OHP in urine, malnutrition, and some traditional consumption practices.

Cellular Stress and Senescence Induction during Trypanosoma cruzi Infection

Chagas disease (CD) is a neglected tropical disease caused by Trypanosoma cruzi infection that, despite being discovered over a century ago, remains a public health problem, mainly in developing countries. Since T. cruzi can infect a wide range of mammalian host cells, parasite–host interactions may be critical to infection outcome. The intense immune stimulation that helps the control of the parasite’s replication and dissemination may also be linked with the pathogenesis and symptomatology worsening. Here, we discuss the findings that support the notion that excessive immune system stimulation driven by parasite persistence might elicit a progressive loss and collapse of immune functions. In this context, cellular stress and inflammatory responses elicited by T. cruzi induce fibroblast and other immune cell senescence phenotypes that may compromise the host’s capacity to control the magnitude of T. cruzi-induced inflammation, contributing to parasite persistence and CD progression. A better understanding of the steps involved in the induction of this chronic inflammatory status, which disables host defense capacity, providing an extra advantage to the parasite and predisposing infected hosts prematurely to immunosenescence, may provide insights to designing and developing novel therapeutic approaches to prevent and treat Chagas disease.

Different Transcriptomic Response to T. cruzi Infection in hiPSC-Derived Cardiomyocytes From Chagas Disease Patients With and Without Chronic Cardiomyopathy

Chagas disease is a tropical zoonosis caused by Trypanosoma cruzi. After infection, the host present an acute phase, usually asymptomatic, in which an extensive parasite proliferation and intense innate immune activity occurs, followed by a chronic phase, characterized by low parasitemia and development of specific immunity. Most individuals in the chronic phase remain without symptoms or organ damage, a state called indeterminate IND form. However, 20 to 40% of individuals develop cardiac or gastrointestinal complications at any time in life. Cardiomyocytes have an important role in the development of Chronic Chagas Cardiomyopathy (CCC) due to transcriptional and metabolic alterations that are crucial for the parasite survival and replication. However, it still not clear why some infected individuals progress to a cardiomyopathy phase, while others remain asymptomatic. In this work, we used hiPSCs-derived cardiomyocytes (hiPSC-CM) to investigate patterns of infection, proliferation and transcriptional response in IND and CCC patients. Our data show that T. cruzi infection and proliferation efficiency do not differ significantly in PBMCs and hiPSC-CM from both groups. However, RNA-seq analysis in hiPSC-CM infected for 24 hours showed a significantly different transcriptional response to the parasite in cells from IND or CCC patients. Cardiomyocytes from IND showed significant differences in the expression of genes related to antigen processing and presentation, as well as, immune co-stimulatory molecules. Furthermore, the downregulation of collagen production genes and extracellular matrix components was significantly different in these cells. Cardiomyocytes from CCC, in turn, showed increased expression of mTORC1 pathway and unfolded protein response genes, both associated to increased intracellular ROS production. These data point to a differential pattern of response, determined by baseline genetic differences between groups, which may have an impact on the development of a chronic outcome with or without the presentation of cardiac symptoms.

Host DNA repair response to oxidative damage is modulated by Trypanosoma cruzi in a strain-dependent manner

The conservation of genomic integrity and stability is essential for cell survival. DNA Damage Responses (DDRs) are considered of paramount importance for all living beings and involve mechanisms of cell cycle regulation and damage-specific DNA repair pathways. Hydrogen peroxide (H₂O₂) is a compound that, in supraphysiological concentrations, damages biomolecules including the DNA, causing base modifications and strand breaks. There is evidence that Trypanosoma cruzi, the protozoan that causes Chagas disease, interferes in the host cell's DNA metabolism. In order to investigate the influence of T. cruzi infection over the host cell capacity to withstand and repair DNA damage, we analyzed L6 cells infected with Berenice, and Colombiana T. cruzi strains according to their viability, proliferation, morphology, DNA degradation, expression of DNA repair, and cell cycle genes following H₂O₂ treatment. It was noted that T. cruzi infection might act as either a stressor or a protective element of host DNA, depending on the strain and H₂O₂ concentration. Cells infected with Berenice strain and treated with 0.8 mM H₂O₂ presented a reduced DNA damage response intensity (e.g., BER and HR). Infection with T. cruzi Colombiana prevented the activation of DNA repair pathways in response to 0.8mM and 1.6mM H₂O₂ (NER and MMR). Nevertheless, since cellular viability was not significantly compromised in Colombiana-infected cells following the oxidative insult, it is possible that the parasite directly influenced the host DNA repair machinery. Our results support the notion that T. cruzi is able to modulate the host cell DNA metabolism in a strain-dependent manner, an event which can be explored in future drug development strategies.

Modulation of the Host Nuclear Compartment by Trypanosoma cruzi Uncovers Effects on Host Transcription and Splicing Machinery

Host manipulation is a common strategy for invading pathogens. Trypanosoma cruzi, the causative agent of Chagas Disease, lives intracellularly within host cells. During infection, parasite-associated modifications occur to the host cell metabolism and morphology. However, little is known about the effect of T. cruzi infection on the host cell nucleus and nuclear functionality. Here, we show that T. cruzi can modulate host transcription and splicing machinery in non-professional phagocytic cells during infection. We found that T. cruzi regulates host RNA polymerase II (RNAPII) in a time-dependent manner, resulting in a drastic decrease in RNAPII activity. Furthermore, host cell ribonucleoproteins associated with mRNA transcription (hnRNPA1 and AB2) are downregulated concurrently. We reasoned that T. cruzi may hijack the host U2AF35 auxiliary factor, a key regulator for RNA processing, as a strategy to affect the splicing machinery activities directly. In support of our hypothesis, we carried out in vivo splicing assays using an adenovirus E1A pre-mRNA splicing reporter, showing that intracellular T. cruzi directly modulates the host cells by appropriating U2AF35. For the first time, our results provide evidence of a complex and intimate molecular relationship between T. cruzi and the host cell nucleus during infection.

Oxidative stress implications for therapeutic vaccine development against Chagas disease

INTRODUCTION

Pathogenesis of Chagas disease (CD) caused by the protozoan parasite Trypanosoma cruzi (T. cruzi) involves chronic oxidative and inflammatory stress. In this review, we discuss the research efforts in therapeutic vaccine development to date and the potential challenges imposed by oxidative stress in achieving an efficient therapeutic vaccine against CD.

AREAS COVERED

This review covers the immune and nonimmune mechanisms of reactive oxygen species production and immune response patterns during T. cruzi infection in CD. A discussion on immunotherapy development efforts, the efficacy of antigen-based immune therapies against T. cruzi, and the role of antioxidants as adjuvants is discussed to provide promising insights to developing future treatment strategies against CD.

EXPERT OPINION

Administration of therapeutic vaccines can be a good option to confront persistent parasitemia in CD by achieving a rapid, short-lived stimulation of type 1 cell-mediated immunity. At the same time, adjunct therapies could play a critical role in the preservation of mitochondrial metabolism and cardiac muscle contractility in CD. We propose combined therapy with antigen-based vaccine and small molecules to control the pathological oxidative insult would be effective in the conservation of cardiac structure and function in CD.

Mechanisms of Ataxia Telangiectasia Mutated (ATM) Control in the DNA Damage Response to Oxidative Stress, Epigenetic Regulation, and Persistent Innate Immune Suppression Following Sepsis

Cells have evolved extensive signaling mechanisms to maintain redox homeostasis. While basal levels of oxidants are critical for normal signaling, a tipping point is reached when the level of oxidant species exceed cellular antioxidant capabilities. Myriad pathological conditions are characterized by elevated oxidative stress, which can cause alterations in cellular operations and damage to cellular components including nucleic acids. Maintenance of nuclear chromatin are critically important for host survival and eukaryotic organisms possess an elaborately orchestrated response to initiate repair of such DNA damage. Recent evidence indicates links between the cellular antioxidant response, the DNA damage response (DDR), and the epigenetic status of the cell under conditions of elevated oxidative stress. In this emerging model, the cellular response to excessive oxidants may include redox sensors that regulate both the DDR and an orchestrated change to the epigenome in a tightly controlled program that both protects and regulates the nuclear genome. Herein we use sepsis as a model of an inflammatory pathophysiological condition that results in elevated oxidative stress, upregulation of the DDR, and epigenetic reprogramming of hematopoietic stem cells (HSCs) to discuss new evidence for interplay between the antioxidant response, the DNA damage response, and epigenetic status.