Acute Trypanosoma cruzi infection is associated with anemia, thrombocytopenia, leukopenia, and bone marrow hypoplasia: reversal by nifurtimox treatment

Effects of Free and Nanoencapsulated Benznidazole in Acute Trypanosoma cruzi Infection: Role of Cholinergic Pathway and Redox Status

Background/Objectives: The Trypanosoma cruzi infection promotes an intense inflammatory process that affects several tissues. The cholinergic system may exert a regulatory immune response and control the inflammatory process. This study aimed to evaluate the comparative effect of free and nanoencapsulated benznidazole in acute T. cruzi infection to assess hematological, biochemical, and oxidative status triggered by the cholinergic system. Methods: For this, fifty female Swiss mice were distributed in eight groups, i.e., uninfected and infected animals under four treatment protocols: untreated (control-CT); vehicle treatment (Eudragit L 100-EL-100); benznidazole treatment (BNZ); and nanoencapsulated benznidazole treatment (NBNZ). After eight treatment days, the animals were euthanized for sample collection. Results: The peak of parasitemia was at day 7 p.i., and the BNZ and NBNZ controlled and reduced the parasite rate but showed no efficacy in terms of total elimination of parasites analyzed by RT-PCR in both infected groups. The infection promotes significant anemia, leukopenia, and thrombocytopenia, which the BNZ improves. There was an increase in AChE activity during infection, leading to a pro-inflammatory response and an increase in M1 and M2 mACh receptors in the BNZ group, showing that the treatment interacted with the cholinergic pathway. In addition, a pro-oxidative response was characterized in the infection and mainly in the infected BNZ and NBNZ groups. The histopathological analysis showed significative splenomegaly and inflammatory infiltrate in the heart, liver, and spleen. Conclusions: The administration of the BNZ or NBNZ reverses hematological, hepatic, and renal alterations through cholinergic signaling and stimulates a pro-inflammatory response during acute T. cruzi infection.

First report of Trypanosoma cruzi infection in urban hedgehog (Atelerix albiventris) in Colombia

Chagas disease (CD) is a zoonotic infection caused by the protozoan parasite Trypanosoma cruzi, affecting over seven million people worldwide. T. cruzi can infect more than 100 species of wild mammals, including opossums, armadillos, bats, carnivores, rodents, and primates, as well as domestic animals like dogs, cats, and exotic pets. This is the first report of T. cruzi infection in an "exotic pet" African hedgehog (Atelerix albiventris), in an endemic area for CD in Colombia. After the patient underwent euthanasia due to worsening clinical signs including diarrhea, thrombocytopenia, leukopenia, and hemiplegia, anatomopathological and histopathological examinations were conducted. Simultaneously, molecular diagnosis and genotyping of T. cruzi were performed using qPCR and Next Generation sequencing of the 18S rRNA gene, respectively. Anatomopathological examination revealed significant changes across various systems, including ulcerative hemorrhagic enteritis, left ventricular hypertrophy, lymphadenitis and diffuse meningeal edema. The main histopathological findings included mononuclear inflammatory reaction, congestion and hemorrhages in several organs, accompanied of amastigote cysts in cardiomyocytes. qPCR confirmed the presence of T. cruzi in heart, lymph node, brain, salivary gland, blood, and spleen. Regarding genotyping analyses, all organs were positive for TcI. This case confirms the susceptibility of A. albiventris to infection with T. cruzi and suggest a potential role for these pets as disseminators of T. cruzi infection in endemic areas. The ecological and epidemiological implications of these findings are discussed here.

Omega-3 and omega-6 polyunsaturated fatty acids and their potential therapeutic role in protozoan infections

Protozoa exert a serious global threat of growing concern to human, and animal, and there is a need for the advancement of novel therapeutic strategies to effectively treat or mitigate the impact of associated diseases. Omega polyunsaturated fatty acids (ω-PUFAs), including Omega-3 (ω-3) and omega-6 (ω-6), are constituents derived from various natural sources, have gained significant attention for their therapeutic role in parasitic infections and a variety of essential structural and regulatory functions in animals and humans. Both ω-3 and ω-6 decrease the growth and survival rate of parasites through metabolized anti-inflammatory mediators, such as lipoxins, resolvins, and protectins, and have both in vivo and in vitro protective effects against various protozoan infections. The ω-PUFAs have been shown to modulate the host immune response by a commonly known mechanism such as (inhibition of arachidonic acid (AA) metabolic process, production of anti-inflammatory mediators, modification of intracellular lipids, and activation of the nuclear receptor), and promotion of a shift towards a more effective immune defense against parasitic invaders by regulation the inflammation like prostaglandins, leukotrienes, thromboxane, are involved in controlling the inflammatory reaction. The immune modulation may involve reducing inflammation, enhancing phagocytosis, and suppressing parasitic virulence factors. The unique properties of ω-PUFAs could prevent protozoan infections, representing an important area of study. This review explores the clinical impact of ω-PUFAs against some protozoan infections, elucidating possible mechanisms of action and supportive therapy for preventing various parasitic infections in humans and animals, such as toxoplasmosis, malaria, coccidiosis, and chagas disease. ω-PUFAs show promise as a therapeutic approach for parasitic infections due to their direct anti-parasitic effects and their ability to modulate the host immune response. Additionally, we discuss current treatment options and suggest perspectives for future studies. This could potentially provide an alternative or supplementary treatment option for these complex global health problems.

Serum proteomics reveals a tolerant immune phenotype across multiple pathogen taxa in wild vampire bats

Bats carry many zoonotic pathogens without showing pronounced pathology, with a few exceptions. The underlying immune tolerance mechanisms in bats remain poorly understood, although information-rich omics tools hold promise for identifying a wide range of immune markers and their relationship with infection. To evaluate the generality of immune responses to infection, we assessed the differences and similarities in serum proteomes of wild vampire bats (Desmodus rotundus) across infection status with five taxonomically distinct pathogens: bacteria (Bartonella spp., hemoplasmas), protozoa (Trypanosoma cruzi), and DNA (herpesviruses) and RNA (alphacoronaviruses) viruses. From 19 bats sampled in 2019 in Belize, we evaluated the up- and downregulated immune responses of infected versus uninfected individuals for each pathogen. Using a high-quality genome annotation for vampire bats, we identified 586 serum proteins but found no evidence for differential abundance nor differences in composition between infected and uninfected bats. However, using receiver operating characteristic curves, we identified four to 48 candidate biomarkers of infection depending on the pathogen, including seven overlapping biomarkers (DSG2, PCBP1, MGAM, APOA4, DPEP1, GOT1, and IGFALS). Enrichment analysis of these proteins revealed that our viral pathogens, but not the bacteria or protozoa studied, were associated with upregulation of extracellular and cytoplasmatic secretory vesicles (indicative of viral replication) and downregulation of complement activation and coagulation cascades. Additionally, herpesvirus infection elicited a downregulation of leukocyte-mediated immunity and defense response but an upregulation of an inflammatory and humoral immune response. In contrast to our two viral infections, we found downregulation of lipid and cholesterol homeostasis and metabolism with Bartonella spp. infection, of platelet-dense and secretory granules with hemoplasma infection, and of blood coagulation pathways with T. cruzi infection. Despite the small sample size, our results suggest that vampire bats have a similar suite of immune mechanisms for viruses distinct from responses to the other pathogen taxa, and we identify potential biomarkers that can expand our understanding of pathogenesis of these infections in bats. By applying a proteomic approach to a multi-pathogen system in wild animals, our study provides a distinct framework that could be expanded across bat species to increase our understanding of how bats tolerate pathogens.

Modulation of haematopoiesis by protozoal and helminth parasites

During inflammation, haematopoietic stem cells (HSCs) in the bone marrow (BM) and periphery rapidly expand and preferentially differentiate into myeloid cells that mediate innate immune responses. HSCs can be directed into quiescence or differentiation by sensing alterations to the haematopoietic niche, including cytokines, chemokines, and pathogen-derived products. Most studies attempting to identify the mechanisms of haematopoiesis have focused on bacterial and viral infections. From intracellular protozoan infections to large multicellular worms, parasites are a global health burden and represent major immunological challenges that remain poorly defined in the context of haematopoiesis. Immune responses to parasites vary drastically, and parasites have developed sophisticated immunomodulatory mechanisms that allow development of chronic infections. Recent advances in imaging, genomic sequencing, and mouse models have shed new light on how parasites induce unique forms of emergency haematopoiesis. In addition, parasites can modify the haematopoiesis in the BM and periphery to improve their survival in the host. Parasites can also induce long-lasting modifications to HSCs, altering future immune responses to infection, inflammation or transplantation, a term sometimes referred to as central trained immunity. In this review, we highlight the current understanding of parasite-induced haematopoiesis and how parasites target this process to promote chronic infections.

Cafeteria diet-induced obesity remodels immune response in acute Trypanosoma cruzi infection

BACKGROUND

Obesity is a global problem associated with several conditions, including hypertension, diabetes, arthritis and cardiovascular diseases. With the increase in the prevalence of obesity in recent years, mostly in developing countries, it is important to study its impact on various diseases, including infectious illnesses, such as Chagas disease, caused by the protozoan Trypanosoma cruzi. Considering that a diet rich in salt, sugar, and fat is associated with obesity, this study aimed to evaluate the influence of cafeteria diet (CAF)-induced obesity on immune responses in T. cruzi-infected rats.

METHODS

Male Wistar Hannover rats were provided with water and food ad libitum (chow group). The CAF-fed groups received a normal rodent diet or CAF. The animals were intraperitoneally infected with 105 trypomastigote forms of the Y strain of T. cruzi present in the whole blood from a previously infected mouse.

RESULTS

CAF-fed rats showed a significant increase in visceral adipose tissue weight compared to chow-fed rats. A significant reduction in CD3+ CD4+ helper splenic T cells was observed in obese-infected rats compared to non-obese-infected rats, as well as CD11b and macrophages. In addition, macrophages from obese animals displayed reduced RT1b levels compared to those from control animals. Moreover, INF-γ, an important factor in macrophage activation, was reduced in obese-infected rats compared with their counterparts.

CONCLUSIONS

These results indicate that a CAF can impair the cell-mediated immune response against T. cruzi.

The Therapeutic Potential of Angeli's Salt in Mitigating Acute Trypanosoma cruzi Infection in Mice

Chagas disease (CD), caused by Trypanosoma cruzi, is a neglected tropical disease prevalent in Latin America. Infected patients are treated to eliminate the parasite, reduce the cardiomyopathy risk, and interrupt the disease transmission cycle. The World Health Organization recognizes benznidazole (BZ) and nifurtimox as effective drugs for CD treatment. In the chronic phase, both drugs have low cure rates and serious side effects. T. cruzi infection causes intense tissue inflammation that controls parasite proliferation and CD evolution. Compounds that liberate nitric oxide (NO) (NO donors) have been used as anti-T. cruzi therapeutics. Currently, there is no evidence that nitroxyl (HNO) affects T. cruzi infection outcomes. This study investigated the effects of the HNO donor Angeli's salt (AS) on C57BL/6 mice infected with T. cruzi (Y strain, 5 × 103 trypomastigotes, intraperitoneally). AS reduced the number of parasites in the bloodstream and heart nests and increased the protective antioxidant capacity of erythrocytes in infected animals, reducing disease severity. Furthermore, in vitro experiments showed that AS treatment reduced parasite uptake and trypomastigote release by macrophages. Taken together, these findings from the murine model and in vitro testing suggest that AS could be a promising therapy for CD.

Oral Trypanosoma cruzi Acute Infection in Mice Targets Primary Lymphoid Organs and Triggers Extramedullary Hematopoiesis

During the acute phase of Chagas disease, Trypanosoma cruzi circulation through the bloodstream leads to high tissue parasitism in the host. In primary lymphoid organs, progenitor cell reduction paralleled transient immunosuppression. Herein we showed that acute oral infection in mice promotes diffuse parasitism in bone marrow cells at 14 and 21 days post-infection (dpi), with perivascular regions, intravascular regions, and regions near the bone being target sites of parasite replication. Phenotypic analysis of hematopoietic differentiation in the bone marrow of infected mice showed that the cell number in the tissue is decreased (lineage-negative and lineage-positive cells). Interestingly, analysis of hematopoietic branching points showed that hematopoietic stem and progenitor cells (HSPCs) were significantly increased at 14 dpi. In addition, the pool of progenitors with stem plasticity (HSC-MPP3), as well as multipotent progenitors (MPPs) such as MPP4, also showed this pattern of increase. In contrast, subsequent progenitors that arise from MPPs, such as common lymphoid progenitors (CLPs), lymphoid-primed MPPs (LMPPs), and myeloid progenitors, were not enhanced; conversely, all presented numeric decline. Annexin V staining revealed that cell death increase in the initial hematopoietic branching point probably is not linked to CLPs and that myeloid progenitors decreased at 14 and 21 dpi. In parallel, our investigation provided clues that myeloid progenitor decrease could be associated with an atypical expression of Sca-1 in this population leading to a remarkable increase on LSK-like cells at 14 dpi within the HSPC compartment. Finally, these results led us to investigate HSPC presence in the spleen as a phenomenon triggered during emergency hematopoiesis due to mobilization or expansion of these cells in extramedullary sites. Splenocyte analysis showed a progressive increase in HSPCs between 14 and 21 dpi. Altogether, our study shows that the bone marrow is a target tissue in T. cruzi orally infected mice, leading to a hematopoietic disturbance with LSK-like cell bias accounting on HSPCs possibly affecting myeloid progenitor numbers. The LMPP and CLP reduction converges with defective thymocyte development. Lastly, it is tempting to speculate that the extramedullary hematopoiesis seen in the spleen is a mechanism involved in the hematological maintenance reported during the acute phase of oral T. cruzi infection.

Diversity and Epidemiology of Bat Trypanosomes: A One Health Perspective

Bats (order Chiroptera) have been increasingly recognised as important reservoir hosts for human and animal pathogens worldwide. In this context, molecular and microscopy-based investigations to date have revealed remarkably high diversity of Trypanosoma spp. harboured by bats, including species of recognised medical and veterinary importance such as Trypanosoma cruzi and Trypanosoma evansi (aetiological agents of Chagas disease and Surra, respectively). This review synthesises current knowledge on the diversity, taxonomy, evolution and epidemiology of bat trypanosomes based on both molecular studies and morphological records. In addition, we use a One Health approach to discuss the significance of bats as reservoirs (and putative vectors) of T. cruzi, with a focus on the complex associations between intra-specific genetic diversity and eco-epidemiology of T. cruzi in sylvatic and domestic ecosystems. This article also highlights current knowledge gaps on the biological implications of trypanosome co-infections in a single host, as well as the prevalence, vectors, life-cycle, host-range and clinical impact of most bat trypanosomes recorded to date. Continuous research efforts involving molecular surveillance of bat trypanosomes are required for improved disease prevention and control, mitigation of biosecurity risks and potential spill-over events, ultimately ensuring the health of humans, domestic animals and wildlife globally.

In vitro and in vivo trypanocidal activity of a benzofuroxan derivative against Trypanosoma cruzi

Chagas disease, caused by Trypanosoma cruzi, is a major public health problem and is described as one of the most neglected diseases worldwide. It affects about 6-7 million people. Currently, only two drugs are available for the treatment of this disease: nifurtimox and benznidazole. However, both drugs are highly toxic and have several side effects, which lead many patients to discontinue treatment. Moreover, these compounds show a significant curative efficacy only in the acute phase of the disease. Therefore, searching for new drugs is necessary. The objective of this study was to evaluate the in vitro and in vivo activity of a benzofuroxan derivative (EA2) against T. cruzi, and to evaluate the hematological and biochemical changes induced by its treatment in animals infected with T. cruzi. The results were then compared with those of healthy controls. In vitro testing was first performed with T. cruzi epimastigote forms. In this experiment, EA2 was diluted at three different concentrations (0.25, 0.50, and 1%). In vitro evaluation of the trypanocidal activity was performed 24, 48, and 72 h after incubation. In vivo assays were performed using three different doses (10, 5, and 2,5 mg/kg). Mice were divided into 10 groups (five animals/group), wherein four groups comprised non-infected animals (A, G, H, I) and six groups comprised infected animals (B, C, D E, F, J). Groups B and J represented the negative and positive controls, respectively. Groups G, H, and I were used to confirm that EA2 was not toxic to non-infected animals. Parasitemia was measured in infected animals and the hematological and biochemical profiles (urea, creatinine, albumin, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) were evaluated in all animals. EA2 demonstrated in vitro trypanocidal activity at all concentrations tested. Although it did not demonstrate a curative effect in vivo, EA2 was able to retard the onset of parasitemia, and significantly reduced the parasite count in groups D and E (treated with 5 and 2.5 mg/kg, respectively). EA2 did not induce changes in hematological and biochemical parameters in non-infected animals, demonstrating that it is not toxic. However, further assessments should aim to confirm the safety of EA2 since this was the first in vitro and in vivo study conducted with this molecule.

Administration of artinm lectin reduces the severity of the acute phase infection with Trypanosoma cruzi

The acute phase of experimental Trypanosoma cruzi infection is associated with a strong inflammatory reaction, physiological changes, amastigote nests in tissues, and hematological alterations. ArtinM, a lectin extracted from Artocarpus heterophyllus seeds, is a homotetramer exhibiting immunomodulatory properties that promotes Th1 immune responses against intracellular pathogens, including the induction of neutrophil migration and increase in IL‐12 production. This study aimed to evaluate the effects of ArtinM on experimental Chagas disease in mice. We evaluated mouse survival curves, parasitemia, hematological parameters including quantification of inflammatory infiltrates, and amastigote nests in cardiac tissue during infection. The results showed a reduced number of parasites in the blood, an increase in animal survival, improvements in hematological parameters, and decrease in inflammatory infiltrates and amastigote nests in the group treated with ArtinM. Collectively, these data suggest that the administration of ArtinM can lower the number of parasites in peak parasitemia caused by the Colombian strain of T. cruzi and can increase survival of infected mice. The observed reduction in cardiac tissue injury may be due to fewer T. cruzi amastigote nests and lower levels of inflammatory infiltrates. This study highlights the need for further investigation into the use of ArtinM as a potential alternative therapeutic for treating Chagas disease.

Host Genetics Background Influence in the Intragastric Trypanosoma cruzi Infection

Background

Considering the complexity of the factors involved in the immunopathology of Chagas disease, which influence the Chagas' disease pathogenesis, anti-T. cruzi immune response, and chemotherapy outcome, further studies are needed to improve our understanding about these relationships. On this way, in this article we analyzed the host genetic influence on hematological, histopathological and immunological aspects after T. cruzi infection.

Methods

BALB/c and A mice were intragastrically infected with T. cruzi SC2005 strain, isolated from a patient of an outbreak of Chagas disease. Parameters such as parasite load, survival rates, cytokines production, macrophages, T and B cell frequencies, and histopathology analysis were carried out.

Results

BALB/c mice presented higher parasitemia and mortality rates than A mice. Both mouse lineages exhibited hematological alterations suggestive of microcytic hypochromic anemia and histopathological alterations in stomach, heart and liver. The increase of CD8+ T cells, in heart, liver and blood, and the increase of CD19+ B cells, in liver, associated with a high level of proinflammatory cytokines (IL-6, TNF-α, IFN-γ), confer a resistance profile to the host. Although BALB/c animals exhibited the same findings observed in A mice, the response to infection occurred later, after a considerable parasitemia increase. By developing an early response to the infection, A mice were found to be less susceptible to T. cruzi SC2005 infection.

Conclusions

Host genetics background shaping the response to infection. The early development of a cytotoxic cellular response profile with the production of proinflammatory cytokines is important to lead a less severe manifestation of Chagas disease.

Differential virulence of Trypanosoma brucei rhodesiense isolates does not influence the outcome of treatment with anti-trypanosomal drugs in the mouse model

We assessed the virulence and anti-trypanosomal drug sensitivity patterns of Trypanosoma brucei rhodesiense (Tbr) isolates in the Kenya Agricultural and Livestock Research Organization-Biotechnology Research Institute (KALRO-BioRI) cryobank. Specifically, the study focused on Tbr clones originally isolated from the western Kenya/eastern Uganda focus of human African Trypanosomiasis (HAT). Twelve (12) Tbr clones were assessed for virulence using groups(n = 10) of Swiss White Mice monitored for 60 days post infection (dpi). Based on survival time, four classes of virulence were identified: (a) very-acute: 0-15, (b) acute: 16-30, (c) sub-acute: 31-45 and (d) chronic: 46-60 dpi. Other virulence biomarkers identified included: pre-patent period (pp), parasitaemia progression, packed cell volume (PCV) and body weight changes. The test Tbr clones together with KALRO-BioRi reference drug-resistant and drug sensitive isolates were then tested for sensitivity to melarsoprol (mel B), pentamidine, diminazene aceturate and suramin, using mice groups (n = 5) treated with single doses of each drug at 24 hours post infection. Our results showed that the clones were distributed among four classes of virulence as follows: 3/12 (very-acute), 3/12 (acute), 2/12 (sub-acute) and 4/12 (chronic) isolates. Differences in survivorship, parasitaemia progression and PCV were significant (P<0.001) and correlated. The isolate considered to be drug resistant at KALRO-BioRI, KETRI 2538, was confirmed to be resistant to melarsoprol, pentamidine and diminazene aceturate but it was not resistant to suramin. A cure rate of at least 80% was achieved for all test isolates with melarsoprol (1mg/Kg and 20 mg/kg), pentamidine (5 and 20 mg/kg), diminazene aceturate (5 mg/kg) and suramin (5 mg/kg) indicating that the isolates were not resistant to any of the drugs despite the differences in virulence. This study provides evidence of variations in virulence of Tbr clones from a single HAT focus and confirms that this variations is not a significant determinant of isolate sensitivity to anti-trypanosomal drugs.

Combination Therapy Using Benznidazole and Aspirin during the Acute Phase of Experimental Chagas Disease Prevents Cardiovascular Dysfunction and Decreases Typical Cardiac Lesions in the Chronic Phase

Chagas disease, caused by the protozoan Trypanosoma cruzi, is one of the main causes of death due to cardiomyopathy and heart failure in Latin American countries. The treatment of Chagas disease is directed at eliminating the parasite, decreasing the probability of cardiomyopathy and disrupting the disease transmission cycle. Benznidazole (BZ) and nifurtimox (Nfx) are recognized as effective drugs for the treatment of Chagas disease by the World Health Organization, but both have high toxicity and limited efficacy, especially in the chronic disease phase. At low doses, aspirin (ASA) has been reported to protect against T. cruzi infection. We evaluated the effectiveness of BZ in combination with ASA at low doses during the acute disease phase and evaluated cardiovascular aspects and cardiac lesions in the chronic phase. ASA treatment prevented the cardiovascular dysfunction (hypertension and tachycardia) and typical cardiac lesions. Moreover, BZ+ASA-treated mice had a smaller cardiac fibrotic area than BZ-treated mice. These results were associated with an increase in numbers of eosinophils and reticulocytes and levels of nitric oxide in the plasma and cardiac tissue of ASA-treated mice relative to respective controls. These effects of ASA and BZ+ASA in chronically infected mice were inhibited by pretreatment with the lipoxin A₄ (LXA₄) receptor antagonist Boc-2, indicating that the protective effects of ASA are mediated by ASA-triggered lipoxin. These results emphasize the importance of exploring new drug combinations for treatments of the acute phase of Chagas disease that are beneficial for patients with chronic disease.

Intravital microscopy: Imaging host-parasite interactions in lymphoid organs

Intravital microscopy allows imaging of biological phenomena within living animals, including host-parasite interactions. This has advanced our understanding of both, the function of lymphoid organs during parasitic infections, and the effect of parasites on such organs to allow their survival. In parasitic research, recent developments in this technique have been crucial for the direct study of host-parasite interactions within organs at depths, speeds and resolution previously difficult to achieve. Lymphoid organs have gained more attention as we start to understand their function during parasitic infections and the effect of parasites on them. In this review, we summarise technical and biological findings achieved by intravital microscopy with respect to the interaction of various parasites with host lymphoid organs, namely the bone marrow, thymus, lymph nodes, spleen and the mucosa-associated lymphoid tissue, and present a view into possible future applications.

Oral Route Driven Acute Trypanosoma cruzi Infection Unravels an IL-6 Dependent Hemostatic Derangement

Oral transmission of Trypanosoma cruzi, the etiologic agent of Chagas disease, is presently the most important route of infection in Brazilian Amazon. Other South American countries have also reported outbreaks of acute Chagas disease associated with food consumption. A conspicuous feature of this route of transmission is presenting symptoms such as facial and lower limbs edema, in some cases bleeding manifestations and risk of thromboembolism are evident. Notwithstanding, studies that address this route of infection are largely lacking regarding its pathogenesis and, more specifically, the crosstalk between immune and hemostatic systems. Here, BALB/c mice were orally infected with metacyclic trypomastigotes of T. cruzi Tulahuén strain and used to evaluate the cytokine response, primary and secondary hemostasis during acute T. cruzi infection. When compared with control uninfected animals, orally infected mice presented higher pro-inflammatory cytokine (TNF-α, IFN-γ, and IL-6) serum levels. The highest concentrations were obtained concomitantly to the increase of parasitemia, between 14 and 28 days post-infection (dpi). Blood counts in the oral infected group revealed concomitant leukocytosis and thrombocytopenia, the latter resulting in increased bleeding at 21 dpi. Hematological changes paralleled with prolonged activated partial thromboplastin time, Factor VIII consumption and increased D-dimer levels, suggest that oral T. cruzi infection relies on disseminated intravascular coagulation. Remarkably, blockade of the IL-6 receptor blunted hematological abnormalities, revealing a critical role of IL-6 in the course of oral infection. These results unravel that acute T. cruzi oral infection results in significant alterations in the hemostatic system and indicates the relevance of the crosstalk between inflammation and hemostasis in this parasitic disease.

In-solution behavior and protective potential of asparagine synthetase A from Trypanosoma cruzi

l-Asparagine synthetase (AS) acts in asparagine formation and can be classified into two families: AS-A or AS-B. AS-A is mainly found in prokaryotes and can synthetize asparagine from ammonia. Distinct from other eukaryotes, Trypanosoma cruzi produces an AS-A. AS-A from Trypanosoma cruzi (Tc-AS-A) differs from prokaryotic AS-A due to its ability to catalyze asparagine synthesis using both glutamine and ammonia as nitrogen sources. Regarding these peculiarities, this work uses several biophysical techniques to provide data concerning the Tc-AS-A in-solution behavior. Tc-AS-A was produced as a recombinant and purified by three chromatography steps. Circular dichroism, dynamic light scattering, and analytical size exclusion chromatography showed that Tc-AS-A has the same fold and quaternary arrangement of prokaryotic AS-A. Despite the tendency of protein to aggregate, stable dimers were obtained when solubilization occurred at pH ≤ 7.0. We also demonstrate the protective efficacy against T. cruzi infection in mice immunized with Tc-AS-A. Our results indicate that immunization with Tc-AS-A might confer partial protection to infective forms of T. cruzi in this particular model.

Immunosuppression in Experimental Chagas Disease Is Mediated by an Alteration of Bone Marrow Stromal Cell Function During the Acute Phase of Infection

After infection with Trypanosoma cruzi, the etiologic agent of Chagas disease, immunosuppression, and apoptosis of mature lymphocytes contribute to the establishment of the parasite in the host and thereby to persistence and pathology in the chronic stage of infection. In a systemic mouse model of experimental Chagas disease, we have demonstrated a strong depletion of mature B cells in the spleen during the first 2 weeks of infection. Remarkably, the decrease in this cell population commenced already in the bone marrow from infected mice and was a concomitant of an increased apoptosis in pro- and pre-B cell populations. Pro- and pre-B cells in the bone marrow showed a significant reduction accompanied by a functional disturbance of bone marrow-derived stromal cells resulting in diminished levels of IL-7, an essential factor for the development of B cell precursors. Ex vivo, stromal cells isolated from the bone marrow of infected mice had a strikingly impaired capacity to maintain the development of pro- and pre-B cells obtained from uninfected animals. Together, the reduction of an active humoral immune response during acute Chagas disease suggests to be an initial immune evasion mechanism of the parasite to establish persistent infection. Therefore, prevention of B cell depletion by rescuing the stromal cells during this early phase, could give rise to new therapeutic approaches.

Outcomes of Trypanosoma cruzi and Trypanosoma evansi infections on health of Southern coati (Nasua nasua), crab-eating fox (Cerdocyon thous), and ocelot (Leopardus pardalis) in the Brazilian Pantanal

The occurrence of Trypanosoma spp. in wild carnivore populations has been intensively investigated during the last decades. However, the impact of these parasites on the health of free-living infected animals has been largely neglected. The Pantanal biome is the world’s largest seasonal wetland, harboring a great diversity of species and habitats. This includes 174 species of mammals, of which 20 belong to the order Carnivora. The present study aimed to investigate the effect of Trypanosoma evansi and Trypanosoma cruzi infections and coinfections on the health of the most abundant carnivores in the Pantanal: coati (Nasua nasua), crab-eating fox (Cerdocyon thous), and ocelot (Leopardus pardalis). We captured 39 coatis, 48 crab-eating foxes, and 19 ocelots. Diagnostic tests showed T. cruzi infection in 7 crab-eating foxes and 5 coatis. Additionally, 7 crab-eating foxes, 10 coatis, and 12 ocelots were positive for T. evansi. We observed coinfections in 9 crab-eating foxes, 8 coatis, and 2 ocelots. This is the first report of T. evansi and T. cruzi infection on the health of free-living ocelots and crab-eating foxes. We showed that single T. evansi or T. cruzi infection, as well as coinfection, caused some degree of anemia in all animals, as well as an indirect negative effect on body condition in coatis and crab-eating foxes via anemia indicators and immune investment, respectively. Furthermore, the vigorous immune investment observed in sampled coatis, crab-eating foxes and ocelots infected by T. evansi, T. cruzi and coinfected can be highly harmful to their health. Overall, our results indicate that single and combined infection with T. evansi and T. cruzi represent a severe risk to the health of wild carnivores in the Pantanal region.

Haematological alterations in non-human hosts infected with Trypanosoma cruzi: a systematic review

American trypanosomiasis is a neglected tropical disease whose spectrum has not been quite understood, including the impact of Trypanosoma cruzi infection on the haematological parameters of different vertebrate hosts. Thus, this study was designed to compare the pattern of haematological changes induced by T. cruzi infection in order to identify possible species-specific differences among taxons. We also aimed at evaluating the use of this parameter as a tool for diagnosis during the acute phase, when symptoms are usually masked. For this purpose, we performed a systematic search on PubMed and Scopus databases to retrieve original studies published until August 2016. Thirty-one studies were selected using Prisma strategy, which were then submitted to data extraction and methodological bias analysis. Half of the studies showed that the number of erythrogram decreased in infected animals, indicating anaemia. In 68.2% of the studies, the total amount of leukogram values increased, suggesting infection. The main methodological limitations were insufficient information for T. cruzi strains identification, inoculation routes and parasitological characterization. Most of the mammalian species analysed showed the same pattern of haematological changes following T. cruzi infection, indicating that haematological parameters might direct the diagnosis of Chagas disease in the initial phase.

Fish oil supplementation benefits the murine host during the acute phase of a parasitic infection from Trypanosoma cruzi

Long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) are known to modulate a variety of immune cell functions. On occasion, this has led to diminished host resistance to certain viral and bacterial infections. Little is known about the impact of n-3 PUFA on host resistance to parasitic infection, however, based on results from a small study conducted more than two decades ago, we hypothesized that providing mice LC n-3 PUFA will diminish host resistance to Trypanosoma cruzi, the parasitic pathogen responsible for Chagas disease. To investigate this, C57BL/6 mice were supplemented by gavage (0.6% v/w) with phosphate-buffered saline, corn oil (CO), or menhaden fish oil (FO, a fat source rich in LC n-3 PUFA) for 15 days prior to T cruzi (Y strain) challenge and throughout the acute phase of infection. FO supplementation was associated with a transient 2-fold greater peak of blood parasitemia at 7 days postinfection (dpi), whereas subsequent cardiac parasitemia was ~60% lower at 12 dpi. FO treatment also ameliorated the leukopenia and thrombocytopenia observed in the early stages of a T cruzi infection. FO supplementation reduced circulating and cardiac nitric oxide at 7 and 12 dpi, respectively. FO supplementation altered ex vivo prostaglandin E₂ and cytokine and chemokine production by splenocytes isolated from uninfected and infected mice. Overall, our results suggest that oral administration of LC n-3 PUFA from FO can have beneficial effects on the host in the early course of a T cruzi infection.

Purinergic ecto-enzymes participate in the thromboregulation in acute in mice infection by Trypanosoma cruzi

Coagulation disorders have been described in Chagas disease with thrombocytopenia as an important event. Several mechanisms may be related to this pathogenesis, such as enzymes of the purinergic system, purine, and receptors involved in the regulation and modulation of physiological events related to hemostasis. Therefore, the aim of this study was to evaluate the activities of E-NTPDase, E-5'nucleotidase, and ecto-adenosine deaminase (E-ADA) in platelets of mice experimentally infected by Trypanosoma cruzi. Twelve female mice were used, divided into two groups (n = 6): uninfected and infected. Mice of infected group were intraperitoneally inoculated with 10⁴ trypomastigotes of T. cruzi (strain Y). On day 12 post-infection (PI), blood samples were collected for quantitation and separation of platelets. A significant reduction in the number of platelets of infected mice (P < 0.05) was observed. The activities of E-NTPDase (ATP and ADP substrates), E-5'nucleotidase, and E-ADA in platelets increased significantly (P < 0.05) in mice infected by T. cruzi compared with uninfected animals. A negative correlation (P < 0.01)was observed between the number of platelets and ATP hydrolysis (r = -0.64), and ADP hydrolysis (r = -0.69) by E-NTPDase. Therefore, there is a response from the purinergic system activating ecto-enzymes in platelets of mice T. cruzi infected, as a compensatory effect of thrombocytopenia.

Purinergic enzymatic activities in lymphocytes and cardiomyocytes of mice acutely infected by Trypanosoma cruzi modulating the inflammatory responses

The aim of this study was to evaluate the activity of purinergic enzymes in lymphocytes and cardiac tissue of mice experimentally infected by Trypanosoma cruzi. Twelve female mice were used, divided into two groups (n = 6): uninfected and infected. On day 12 post-infection (PI), the animals were anesthetized and after euthanized, and samples were collected for analyses. Infected mice showed reduction in erythrocyte counts, hematocrit and hemoglobin concentration, as well as reduced number of total leukocytes in consequence of neutrophilia (P < 0.01). The number of monocytes increased in infected mice (P < 0.001), however the number of lymphocytes and eosinophils did not differ between groups (P > 0.05). The E-NTPDase (ATP and ADP substrate) and E-ADA activities in lymphocytes increased significantly in mice infected by T. cruzi (P < 0.01). In the heart, multiple pseudocysts containing amastigotes within cardiomyocytes were observed, as well as focally extensive severe necrosis associated with diffuse moderate to severe inflammatory infiltrate of lymphocytes. Although, the NTPDase activity (ATP and ADP substrate) in the cardiac homogenate did not differ between groups, a reduction on 5'-nucleotidase activity (P < 0.001) and an increase in the ADA activity in infected animals (P < 0.05) were observed. Thus, animals infected by T. cruzi experienced the disease, i.e., showed anemia, leucopenia, and heart lesions. Associated with this, purinergic enzymes showed altered activities, which might be related to the modulation of the inflammatory response.

Murine models susceptibility to distinctTrypanosoma cruziI genotypes infection

Chagas disease is a complex zoonosis that affects around 8 million people worldwide. This pathology is caused byTrypanosoma cruzi, a kinetoplastid parasite that shows tremendous genetic diversity evinced in six distinct Discrete Typing Units (TcI-TcVI) including a recent genotype named as TcBat and associated with anthropogenic bats. TcI presents a broad geographical distribution and has been associated with chronic cardiomyopathy. Recent phylogenetic studies suggest the existence of two genotypes (Domestic (TcIDom) and sylvatic TcI) within TcI. The understanding of the course of the infection in different mouse models by these two genotypes is not yet known. Therefore, we infected 126 animals (ICR-CD1, National Institute of Health (NIH) and Balb/c) with two TcIDomstrains and one sylvatic strain for a follow-up period of 60 days. We quantified the parasitaemia, immune response and histopathology observing that the maximum day of parasitaemia was achieved at day 21 post-infection. Domestic strains showed higher parasitaemia than the sylvatic strain in the three mouse models; however in the survival curves Balb/c mice were less susceptible to infection compared with NIH and ICR-CD1. Our results suggest that the genetic background plays a fundamental role in the natural history of the infection and the sympatric TcI genotypes have relevant implications in disease pathogenesis.

Co-Infection and Wild Animal Health: Effects of Trypanosomatids and Gastrointestinal Parasites on Coatis of the Brazilian Pantanal

Wild animals are infected by diverse parasites, but how they influence host health is poorly understood. We examined the relationship of trypanosomatids and gastrointestinal parasites with health of wild brown-nosed coatis (Nasua nasua) from the Brazilian Pantanal. We used coati body condition and hematological parameters as response variables in linear models that were compared using an information theoretic approach. Predictors were high/low parasitemias by Trypanosoma cruzi and T. evansi, and indices representing the abundance of distinct groups of gastrointestinal parasites. We also analyzed how host health changed with host sex and reproductive seasonality. Hemoparasites was best related to coati body condition and hematological indices, whereas abundance of gastrointestinal parasites was relatively less associated with coati health. Additionally, some associations were best predicted by models that incorporated reproductive seasonality and host sex. Overall, we observed a lower health condition during the breeding season, when coatis are under reproductive stress and may be less able to handle infection. In addition, females seem to handle infection better than males. Body condition was lower in coatis with high parasitemias of T. evansi, especially during the reproductive season. Total red blood cell counts, packed cell volume, platelets and eosinophils were also lower in animals with high T. evansi parasitemias. Total white blood cell counts and mature neutrophils were lower in animals with high parasitemias for both Trypanosoma species, with neutrophils decreasing mainly during the reproductive season. Overall, decreases in hematological parameters of females with T. evansi high parasitemias were less evident. For T. cruzi, monocytes decreased in individuals with high parasitemias. High abundances of microfilariae in the bloodstream, and cestode eggs and coccidian oocysts in feces were also associated with coati blood parameters. This study shows the potential value of examining hematological parameters as an approach to better understand the ecological relevance of parasite-host interactions.

Oral Outbreak of Chagas Disease in Santa Catarina, Brazil: Experimental Evaluation of a Patient's Strain

Chagas disease is a worldwide public health problem. Although the vectorial transmission of Chagas disease has been controlled in Brazil there are other ways of transmission, such as the ingestion of T. cruzi contaminated food, which ensures the continuation of this zoonosis. Here, we demonstrate the influence of the inoculation route on the establishment and development of the SC2005 T. cruzi strain infection in mice. Groups of Swiss mice were infected intragastrically (IG) or intraperitoneally (IP) with the T. cruzi SC2005 strain derived from an outbreak of oral Chagas disease. The results revealed that 100% of IP infected mice showed parasitemia, while just 36% of IG infected showed the presence of the parasite in blood. The parasitemia peaks were later and less intense in the IG infected mice. Mortality of the IP infected animals was more intense and earlier when compared to the IG infected mice. In the IP infected mice leucopenia occurred in the early infection followed by leucocytosis, correlating positively with the increase of the parasites. However, in the IG infected mice only an increase in monocytes was observed, which was positively correlated with the increase of the parasites. Histopathological analyses revealed a myotropic pattern of the SC2005 strain with the presence of inflammatory infiltrates and parasites in different organs of the animals infected by both routes as well as fibrosis foci and collagen redistribution. The flow cytometric analysis demonstrated a fluctuation of the T lymphocyte population in the blood, spleen and mesenteric lymph nodes of the infected animals. T. cruzi DNA associated with the presence of inflammatory infiltrates was detected by PCR in the esophagus, stomach and intestine of all infected mice. These findings are important for the understanding of the pathogenesis of T. cruzi infection by both inoculation routes.

The TcI and TcII Trypanosoma cruzi experimental infections induce distinct immune responses and cardiac fibrosis in dogs

Trypanosoma cruzi infection may be caused by different strains with distinct discrete typing units (DTUs) that can result in variable clinical forms of chronic Chagas disease. The present study evaluates the immune response and cardiac lesions in dogs experimentally infected with different T. cruzi strains with distinct DTUs, namely, the Colombian (Col) and Y strains of TcI and TcII DTU, respectively. During infection with the Col strain, increased levels of alanine aminotransferase, erythrocytes, haematocrit and haemoglobin were observed. In addition, CD8⁺ T-lymphocytes isolated from the peripheral blood produced higher levels of interleukin (IL)-4. The latter suggests that during the acute phase, infection with the Col strain may remain unnoticed by circulating mononuclear cells. In the chronic phase, a significant increase in the number of inflammatory cells was detected in the right atrium. Conversely, infection with the Y strain led to leucopoenia, thrombopoenia, inversion of the ratio of CD4⁺/CD8⁺ T-lymphocytes and alterations in monocyte number. The Y strain stimulated the production of interferon-γ by CD4⁺ and CD8⁺ T-lymphocytes and IL-4 by CD8⁺ T-cells. In the chronic phase, significant heart inflammation and fibrosis were observed, demonstrating that strains of different DTUs interact differently with the host.

Significance of algal polymer in designing amphotericin B nanoparticles

Development of oral amphotericin B (AmB) loaded nanoparticles (NPs) demands a novel technique which reduces its toxicity and other associated problems. Packing of AmB in between two oppositely charged ions by polyelectrolyte complexation technique proved to be a successful strategy. We have developed a novel carrier system in form of polyelectrolyte complex of AmB by using chitosan (CS) and porphyran (POR) as two oppositely charged polymers with TPP as a crosslinking agent. Initially POR was isolated from Porphyra vietnamensis followed by the fact that its alkali induced safe reduction in molecular weight was achieved. Formulation was optimized using three-factor three-level (3³) central composite design. High concentration of POR in NPs was confirmed by sulfated polysaccharide (SP) assay. Degradation and dissolution studies suggested the stability of NPs over wide pH range. Hemolytic toxicity data suggested the safety of prepared formulation. In vivo and in vitro antifungal activity demonstrated the high antifungal potential of optimized formulation when compared with standard drug and marketed formulations. Throughout the study TPP addition did not cause any significant changes. Therefore, these experimental oral NPs may represent an interesting carrier system for the delivery of AmB.

The acute phase of Trypanosoma cruzi infection is attenuated in 5-lipoxygenase-deficient mice

In the present work we examine the contribution of 5-lipoxygenase- (5-LO-) derived lipid mediators to immune responses during the acute phase of Trypanosoma cruzi infection in 5-LO gene knockout (5-LO(-/-)) mice and wild-type (WT) mice. Compared with WT mice, the 5-LO(-/-) mice developed less parasitemia/tissue parasitism, less inflammatory cell infiltrates, and a lower mortality. This resistance of 5-LO(-/-) mice correlated with several differences in the immune response to infection, including reduced PGE2 synthesis; sustained capacity of splenocytes to produce high levels of interleukin (IL)-12 early in the infection; enhanced splenocyte production of IL-1β, IL-6, and IFN-γ; rapid T-cell polarization to secrete high quantities of IFN-γ and low quantities of IL-10; and greater numbers of CD8(+)CD44(high)CD62L(low) memory effector T cells at the end of the acute phase of infection. The high mortality in WT mice was associated with increased production of LTB4/LTC4, T cell bias to produce IFN-γ, high levels of serum nitrite, and marked protein extravasation into the peritoneal cavity, although survival was improved by treatment with a cys-LT receptor 1 antagonist. These data also provide evidence that 5-LO-derived mediators negatively affect host survival during the acute phase of T. cruzi infection.

Oral exposure to Phytomonas serpens attenuates thrombocytopenia and leukopenia during acute infection with Trypanosoma cruzi

Mice infected with Trypanosoma cruzi, the agent of Chagas disease, rapidly develop anemia and thrombocytopenia. These effects are partially promoted by the parasite trans-sialidase (TS), which is shed in the blood and depletes sialic acid from the platelets, inducing accelerated platelet clearance and causing thrombocytopenia during the acute phase of disease. Here, we demonstrate that oral immunization of C57BL/6 mice with Phytomonas serpens, a phytoflagellate parasite that shares common antigens with T. cruzi but has no TS activity, reduces parasite burden and prevents thrombocytopenia and leukopenia. Immunization also reduces platelet loss after intraperitoneal injection of TS. In addition, passive transfer of immune sera raised in mice against P. serpens prevented platelet clearance. Thus, oral exposure to P. serpens attenuates the progression of thrombocytopenia induced by TS from T. cruzi. These findings are not only important for the understanding of the pathogenesis of T. cruzi infection but also for developing novel approaches of intervention in Chagas disease.

NATURAL INFECTION BY Trypanosoma cruzi IN ONE DOG IN CENTRAL WESTERN BRAZIL: A CASE REPORT

SUMMARY It is estimated that about 10 million people are infected with Trypanosoma cruzi worldwide, mostly in Latin America and more than 25 million are at risk of acquiring this infection in endemic areas. Dogs are an important reservoir for this pathogen and thus, considered a risk factor for human populations. This report describes one case of Chagas disease in a dog from Cuiabá, Mato Grosso State, Brazil. The diagnosis was obtained by direct examination of trypomastigote forms in blood smears. Amastigotes forms were visualized in microscopy of the bone marrow, lymph nodes, kidneys, liver and brain. The T. cruzi (ZIII) infection was confirmed by Polymerase Chain Reaction, and sequencing. The animal presented multisystemic failure and died. Although acute Chagas disease in humans is not reported in Cuiabá, this is the first report of a canine case in this region. This case represents a warning, to health professionals and authorities, to the possibility of transmission of this zoonosis in Cuiabá.

Hematological alterations during experimental canine infection by Trypanosoma cruzi

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

Splenectomy increases mortality in murine Trypanosoma cruzi infection

The spleen is a secondary lymphoid organ that harbours a variety of cells such as T and B lymphocytes and antigen-presenting cells important to immune response development. In this study, we evaluated the impact of spleen removal in the immune response to experimental Trypanosoma cruzi infection. C57BL/6 mice were infected with Y strain of the parasite and infection was followed daily. Mice that underwent splenectomy had fewer parasites in peripheral blood at the peak of infection; however, mortality was increased. Histological analysis of heart and liver tissues revealed an increased number of parasites and inflammatory infiltrates at these sites. Spleen removal was associated with reduction in IFN-γ and TNF-α production during infection as well as with a decrease in specific antibody secretion. Haematological disorders were also detected. Splenectomized mice exhibited severe anaemia and decreased bone marrow cell numbers. Our results indicate that spleen integrity is critical in T. cruzi infection for the immune response against the parasite, as well as for the control of bone marrow haematological function.

Coinfection with different Trypanosoma cruzi strains interferes with the host immune response to infection

A century after the discovery of Trypanosoma cruzi in a child living in Lassance, Minas Gerais, Brazil in 1909, many uncertainties remain with respect to factors determining the pathogenesis of Chagas disease (CD). Herein, we simultaneously investigate the contribution of both host and parasite factors during acute phase of infection in BALB/c mice infected with the JG and/or CL Brener T. cruzi strains. JG single infected mice presented reduced parasitemia and heart parasitism, no mortality, levels of pro-inflammatory mediators (TNF-α, CCL2, IL-6 and IFN-γ) similar to those found among naïve animals and no clinical manifestations of disease. On the other hand, CL Brener single infected mice presented higher parasitemia and heart parasitism, as well as an increased systemic release of pro-inflammatory mediators and higher mortality probably due to a toxic shock-like systemic inflammatory response. Interestingly, coinfection with JG and CL Brener strains resulted in intermediate parasitemia, heart parasitism and mortality. This was accompanied by an increase in the systemic release of IL-10 with a parallel increase in the number of MAC-3(+) and CD4(+) T spleen cells expressing IL-10. Therefore, the endogenous production of IL-10 elicited by coinfection seems to be crucial to counterregulate the potentially lethal effects triggered by systemic release of pro-inflammatory mediators induced by CL Brener single infection. In conclusion, our results suggest that the composition of the infecting parasite population plays a role in the host response to T. cruzi in determining the severity of the disease in experimentally infected BALB/c mice. The combination of JG and CL Brener was able to trigger both protective inflammatory immunity and regulatory immune mechanisms that attenuate damage caused by inflammation and disease severity in BALB/c mice.

Iron metabolism in trypanosomatids, and its crucial role in infection

Iron is almost ubiquitous in living organisms due to the utility of its redox chemistry. It is also dangerous as it can catalyse the formation of reactive free radicals - a classical double-edged sword. In this review, we examine the uptake and usage of iron by trypanosomatids and discuss how modulation of host iron metabolism plays an important role in the protective response. Trypanosomatids require iron for crucial processes including DNA replication, antioxidant defence, mitochondrial respiration, synthesis of the modified base J and, in African trypanosomes, the alternative oxidase. The source of iron varies between species. Bloodstream-form African trypanosomes acquire iron from their host by uptake of transferrin, and Leishmania amazonensis expresses a ZIP family cation transporter in the plasma membrane. In other trypanosomatids, iron uptake has been poorly characterized. Iron-withholding responses by the host can be a major determinant of disease outcome. Their role in trypanosomatid infections is becoming apparent. For example, the cytosolic sequestration properties of NRAMP1, confer resistance against leishmaniasis. Conversely, cytoplasmic sequestration of iron may be favourable rather than detrimental to Trypanosoma cruzi. The central role of iron in both parasite metabolism and the host response is attracting interest as a possible point of therapeutic intervention.

Trypanosoma cruzi: biodistribution of technetium-99m pertechnetate in infected rats

With the aim of investigating the biodistribution of technetium-99m pertechnetate ((99m)TcO4-) in rats infected with Y strain of Tripanosoma Cruzi, at the peak of parasitemia, (14th day of infection), we injected Wistar rats with 0.1 ml of (99m)TcO4- (3.7MBq). After 60 min, the percentage of radioactivity per gram was counted in several isolated organs and blood, using a gamma counter (1470 Wizard, PerkinElmer Finland). The uptake of (99m)TcO4- increased significantly in blood and decreased in the colon of infected animals (p<0.05). A significant reduction in serum iron and red blood cells and a significant increase in total proteins, leukocytes and lymphocytes in the infected rats were observed, compared with controls (p<0.05). A reduction in muscle layer thickness of the colon and mononuclear inflammation were observed. These results conclusively demonstrate that T. cruzi infection would be associated with changes in the biodistribution of (99m)TcO4- and in colon morphology, with potential clinical implications.

Fase aguda da doença de Chagas na Amazônia brasileira: estudo de 233 casos do Pará, Amapá e Maranhão observados entre 1988 e 2005

Foram estudados 233 casos de fase aguda da doença de Chagas, oriundos do Pará, Amapá e Maranhão, observados no período de 1988 a 2005, cento e sessenta deles retrospectivamente de 1988 a 2002 e setenta e três prospectivamente de 2003 a 2005. Entre os casos estudados 78,5% (183/233) faziam parte de surtos provavelmente por transmissão oral, acometendo em média 4 pessoas e 21,5% (50/233) eram casos isolados. Foram considerados casos agudos aqueles que apresentaram exames parasitológicos diretos (a fresco, gota espessa ou Quantitative Buffy Coat - QBC) e/ou IgM anti-Trypanosoma cruzi positivos. Foram feitos ainda xenodiagnósticos em 224 pacientes e hemoculturas em 213. Todos foram avaliados clinica e epidemiologicamente. As manifestações clínicas mais freqüentes foram febre (100%), cefaléia (92,3%), mialgia (84,1%), palidez (67%), dispnéia (58,4%), edema de membros inferiores (57,9%), edema de face (57,5%) dor abdominal (44,2%), miocardite (39,9%) e exantema (27%). O eletrocardiograma mostrou alterações de repolarização ventricular em 38,5% dos casos, baixa voltagem de QRS em 15,4% e desvio de SAQRS em 11,5%, extra-sístoles ventriculares em 5,8%, bradicardia em 5,8% e taquicardia em 5,8%, bloqueio de ramo direito em 4,8% e fibrilação atrial em 4,8%. A alteração mais freqüente vista no ecocardiograma foi o derrame pericárdico em 46,2% dos casos. Treze (5,6%) pacientes evoluíram para o óbito, 10 (76,9%) dos quais por comprometimento cardiovascular, dois por complicações de origem digestiva e um de causa mal definida.