Search

Chagas disease is a neglected illness caused by Trypanosoma cruzi and its treatment is done only with two drugs, nifurtimox and benznidazole. However, both drugs are ineffective in the chronic phase, in addition to causing serious side effects. This context of therapeutic limitation justifies the continuous research for alternative drugs. Here, we study the in vitro trypanocidal effects of the non-steroidal anti-inflammatory drug nimesulide, a molecule that has in its chemical structure a toxicophoric nitroaromatic group (NO2). The set of results obtained in this work highlights the potential for repurposing nimesulide in the treatment of this disease that affects millions of people around the world., Competing Interests: The authors have declared that no competing interests exist.

Trypanosoma cruzi is the causative agent of Chagas disease which affects 8 million people in Latin America. The parasite possesses high capacity to evade host immune system and the available drugs to treat Chagas disease present low efficacy combined to serious side effects to patients. Therefore, the identification of alternative therapeutics is essential. Brazilian flora exhibits an immense diversity of metabolites with great potential to be developed into new drugs. We investigated the action of 2″,3″-dihydroochnaflavone a biflavonoid extracted from Luxemburgia nobilis Eichler ex Engl. (Ochnaceae) against T. cruzi (Y strain). Our experiments showed that this compound is effective against parasite epimastigote forms, presenting IC 50 value of (2.5 ± 0.1) μM after 96 h of treatment. Ultrastructure alterations were also detected in treated epimastigotes especially mitochondrial enlargement at the kinetoplast region. At the concentration of 30 μM, the compound killed (61.6 ± 3.37)% of the parasite in its amastigote form. In addition, at the same concentration, the compound killed all trypamastigotes growing within murine macrophages after 7-9 days of infection. Nonetheless, the biflavonoid concentrations were harmless to murine enriched population of lymphocytes and peritoneal macrophages. These results indicate that 2″,3″- dihydroochnaflavone presents activity against T. cruzi., Competing Interests: Declaration of competing interest On behalf of all authors, the corresponding author states that there is no conflict of interest., (Copyright © 2020. Published by Elsevier B.V.)

Neutrophils are involved in the initial steps of most responses to pathogens and are essential components of the innate immune response. Due to the ability to produce and release various soluble mediators, neutrophils may participate in the regulation of the inflammatory response. Little is known about the role of neutrophils during protozoan infections including infection by Trypanosoma cruzi. In the present study we investigated the importance of inflammatory neutrophils on macrophage activation and T. cruzi replication in vitro, in cells obtained from BALB/c mice and C57Bl/6 mice. Co-cultures of BALB/c apoptotic or live neutrophils with infected peritoneal macrophages resulted in increased replication of the parasites and in the production of TGF-β and PGE2. The treatment with anti-TGF-β neutralizing antibody and COX inhibitor blocked the parasite replication in vitro. On the other hand, co-cultures of T. cruzi infected macrophages with live neutrophils isolated from C57BL/6 mice resulted in decreased number of trypomastigotes in culture and increased production of TNF-α and NO. The addition of anti-TNF-α neutralizing antibody or elastase inhibitor resulted in the abolishment of macrophage microbicidal effect and increased parasite replication. Addition of elastase to infected macrophages reduced the replication of the parasites, and on the other hand, addition of a selective inhibitor of iNOS increased parasite growth, suggesting the role of NO in this system. Our findings reveal that neutrophils may regulate T. cruzi experimental infection and determine susceptibility and resistance to infection.

The interactions between cell and cellular matrix confers plasticity to each body tissue, influencing the cellular migratory capacity. Macrophages rely on motility to promote their physiological function. These phagocytes are determinant for the control of invasive infections, and their immunological role largely depends on their ability to migrate and adhere to tissue. Therefore, they interact with the components of the extracellular matrix through their adhesion receptors, conferring morphological modifications that change their shape during migration. Nevertheless, the need to use in vitro cell growth models with the conditioning of three-dimensional synthetic matrices to mimic the dynamics of cell-matrix interaction has been increasingly studied. This becomes more important to effectively understand the changes occurring in phagocyte morphology in the context of infection progression, such as in Chagas disease. This disease is caused by the intracellular pathogen Trypanosoma cruzi, capable of infecting macrophages, determinant cells in the anti-trypanosomatid immunity. In the present study, we sought to understand how an in vitro extracellular matrix model interferes with T. cruzi infection in macrophages. Using different time intervals and parasite ratios, we evaluated the cell morphology and parasite replication rate in the presence of 3D collagen I matrix. Nevertheless, microscopy techniques such as scanning electron microscopy were crucial to trace macrophage-matrix interactions. In the present work, we demonstrated for the first time that the macrophage-matrix interaction favors T. cruzi in vitro replication and the release of anti-inflammatory cytokines during macrophage infection, in addition to drastically altering the morphology of the macrophages and promoting the formation of migratory macrophages. [ABSTRACT FROM AUTHOR]

Nitroimidazoles are pharmacophoric groups responsible for important antiparasitic activity against several infectious diseases. 2-Nitroimidazoles are found in some antiparasitic drugs and are one of the main moieties responsible for the biological activities exhibited. As an example, we can mention the drug benznidazole, the only drug available in Brazil for the treatment of Chagas disease. This work describes an efficient methodology for the synthesis of 2-nitro-1-vinyl-1H-imidazole through a simple and direct approach, as well as its full characterization and biological assessment. The antiparasitic evaluation of 2-nitro-1-vinyl-1H-imidazole against Trypanosoma cruzi (Tulahuen C2C4-LacZ strain) showed IC50 = 4.8 μM on amastigotes and low cytotoxicity against LLC-MK2 cells (IC50 > 500 μM), validating 2-nitro-1-vinyl-1H-imidazole as a biologically active structural subunit for anti-T. cruzi activity. The results presented herein demonstrate that 2-nitro-1-vinyl-1H-imidazole can be easily obtained, possessing great potential for use in the design of new antichagasic drugs through a molecular hybridization strategy using known coupling reactions. [ABSTRACT FROM AUTHOR]

B-1 cells can directly and indirectly influence the immune response. These cells are known to be excellent producers of natural antibodies and can secrete a variety of immunomodulatory molecules. They are also able to differentiate into B-1 cell-derived phagocytes (B-1CDP). B-1 cells can modulate macrophages to become less effective, and B-1CDP cells are more susceptible in infection models. In this work, we investigated the microbicidal ability of these cells in Trypanosoma cruzi infection in vitro. The results show that macrophages from BALB/c mice are more susceptible to infection than macrophages from XID mice. The resistance observed in macrophages from XID mice was abolished in the presence of B-1 cells, and this event seems to be associated with IL-10 production by B-1 cells, which may have contributed to the decrease of NO production. Additionally, B-1CDP cells were more permissive to intracellular T. cruzi infection than peritoneal macrophages. These findings strongly suggest that B-1 cells and B-1CDP cells have a potential role in the persistence of the parasite in host cells. [ABSTRACT FROM AUTHOR]

Trypanosoma cruzi is an obligatory intracellular protozoan parasite, and it is the etiological agent of Chagas' disease that is endemic in the Americas. In addition to humans, a wide spectrum of mammals can be infected by T. cruzi, including dogs. Dogs develop acute and chronic disease, similar to human infection. T. cruzi can infect almost all cell types and after cell invasion, the metacyclics trypomastigotes localize in the cytoplasm, where they transform into amastigotes, the replicative form of T. cruzi in mammals. After amastigote multiplication and differentiation, parasites lyse host cells and spread through the body by blood circulation. In this work, we evaluated the in vitro ability of T. cruzi to infect a canine macrophage cell line DH82 compared with RAW264.7, a murine tissue culture macrophage. Our results have shown that the T. cruzi is able to infect, replicate and differentiate in DH82 cell line. We observed that following treatment with LPS and IFN-γ DH82 cells were more resistant to infection and that resistance was not related reactive oxygen species production in our system. In this study, we also found that DH82 cells became more susceptible to T. cruzi infection when cocultured with apoptotic cells. The analysis of cytokine production has showed elevated levels of the TGF-β, IL-10, and TNF-α produced by T. cruzi-infected canine macrophages. Additionally, we demonstrated a reduced expression of the MHC class II and CD80 by infected DH82 cell line. [ABSTRACT FROM AUTHOR]

Neutrophils are involved in the initial steps of most responses to pathogens and are essential components of the innate immune response. Due to the ability to produce and release various soluble mediators, neutrophils may participate in the regulation of the inflammatory response. Little is known about the role of neutrophils during protozoan infections including infection by Trypanosoma cruzi. In the present study we investigated the importance of inflammatory neutrophils on macrophage activation and T. cruzi replication in vitro, in cells obtained from BALB/c mice and C57Bl/6 mice. Co-cultures of BALB/c apoptotic or live neutrophils with infected peritoneal macrophages resulted in increased replication of the parasites and in the production of TGF-β and PGE2. The treatment with anti-TGF-β neutralizing antibody and COX inhibitor blocked the parasite replication in vitro. On the other hand, co-cultures of T. cruzi infected macrophages with live neutrophils isolated from C57BL/6 mice resulted in decreased number of trypomastigotes in culture and increased production of TNF-α and NO. The addition of anti-TNF-α neutralizing antibody or elastase inhibitor resulted in the abolishment of macrophage microbicidal effect and increased parasite replication. Addition of elastase to infected macrophages reduced the replication of the parasites, and on the other hand, addition of a selective inhibitor of iNOS increased parasite growth, suggesting the role of NO in this system. Our findings reveal that neutrophils may regulate T. cruzi experimental infection and determine susceptibility and resistance to infection. [ABSTRACT FROM AUTHOR]