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

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.

Infection by Trypanosoma cruzi in the central nervous system in non-human mammals: a systematic review

Currently, the types and distribution of the lesions induced in the central nervous system (CNS) by Trypanosoma cruzi remain unclear as the available evidence is based on fragmented data. Therefore, we developed a systematic review to analyse the main characteristics of the CNS lesions in non-human hosts infected. From a structured search on the PubMed/Medline and Scopus platforms, 32 studies were retrieved, subjected to data extraction and methodological bias analysis. Our results show that the most frequent alterations in the CNS are the presence of different forms of T. cruzi and intense lymphocytes infiltrates. The encephalon is the main target of T. cruzi, and inflammatory changes in the CNS are more frequent and severe in the acute phase of infection. The parasite's genotype and phenotype are associated with the tropism and severity of the CNS lesions. The methodological limitations found in the studies were divergences in inoculation pathways, under-reporting of animal age and weight, sample calculation strategies and histopathological characterization. Since the changes were dependent on the pathogenicity and virulence of the T. cruzi strains, the genotype and phenotype characterization of the parasite are extremely relevant to predict changes in the CNS and the neurological manifestations associated with Chagas' disease.

In silico identification and evaluation of new Trypanosoma cruzi trypanothione reductase (TcTR) inhibitors obtained from natural products database of the Bahia semi-arid region (NatProDB)

Trypanosoma cruzi Trypanothione Reductase (TcTR) is one of the therapeutic targets studied in the development of new drugs against Chagas' disease. Due to its biodiversity, Brazil has several compounds of natural origin that were not yet properly explored in drug discovery. Therefore, we employed the Virtual Screening against TcTR aiming to discover new inhibitors from the Natural Products Database of the Bahia Semi-Arid region (NatProDB). This database has a wide chemical diversity favoring the discovery of new chemical entities. Subsequently, we analyzed the best docking conformations using self-organizing maps (AuPosSOM) aiming to verify their interaction sites at TcTR. Finally, the Pred-hERG, the Aggregator Advisor, the FAF-DRUGS and the pkCSM results allowed us to evaluate, respectively, the cardiotoxicity, aggregation capacity, presence of false positives (PAINS) and its toxicity. Thus, we selected three molecules that could be tested in in vitro assays in the hope that the computational results reported here would favor the development of new anti-chagasic drugs.

The Role of Co-Stimulatory Molecules in Chagas Disease

Chagas disease, caused by Trypanosoma cruzi, is a potentially life-threatening tropical disease endemic to Latin American countries that affects approximately 8 million people. In the chronic phase of the disease, individuals are classified as belonging to the indeterminate clinical form or to the cardiac and/or digestive forms when clinical symptoms are apparent. The relationship between monocytes and lymphocytes may be an important point to help clarify the complexity that surrounds the clinical symptoms of the chronic phase of Chagas disease. The co-stimulatory signals are essential to determining the magnitude of T cell response to the antigen. The signals are known to determine the regulation of subsequent adaptive immune response. However, little is known about the expression and function of these molecules in Chagas disease. Therefore, this review aims to discuss the possible role of main pathways of co-stimulatory molecule-receptor interactions in this pathology that could be crucial to understand the disease dynamics.

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.

Oral Versus Intragastric Inoculation: Similar Pathways of Trypanosoma cruzi Experimental Infection? From Target Tissues, Parasite Evasion, and Immune Response

Currently, oral infection is the most frequent transmission mechanism of Chagas disease in Brazil and others Latin American countries. This transmission pathway presents increased mortality rate in the first 2 weeks, which is higher than the calculated mortality after the biting of infected insect vectors. Thus, the oral route of Trypanosoma cruzi infection, and the consequences in the host must be taken into account when thinking on the mechanisms underlying the natural history of the disease. Distinct routes of parasite entry may differentially affect immune circuits, stimulating regional immune responses that impact on the overall profile of the host protective immunity. Experimental studies related to oral infection usually comprise inoculation in the mouth (oral infection, OI) or gavage (gastrointestinal infection, GI), being often considered as similar routes of infection. Hence, establishing a relationship between the inoculation site (OI or GI) with disease progression and the mounting of T. cruzi-specific regional immune responses is an important issue to be considered. Here, we provide a discussion on studies performed in OI and GI in experimental models of acute infections, including T. cruzi infection.