Schiff bases complexed with iron and their relation with the life cycle and infection by Schistosoma mansoni

Introduction

The trematode Schistosoma mansoni causes schistosomiasis, and this parasite's life cycle depends on the mollusk Biomphalaria glabrata. The most effective treatment for infected people is administering a single dose of Praziquantel. However, there are naturally resistant to treatment. This work has developed, considering this parasite's complex life cycle.

Methods

The synthetics compound were evaluated: i) during the infection of B. glabrata, ii) during the infection of BALB/c mice, and iii) during the treatment of mice infected with S. mansoni.

Results and Discussion

For the first objective, snails infected with miracidia treated with compounds C1 and C3 at concentrations of 25% IC50 and 50% IC50, after 80 days of infection, released fewer cercariae than the infected group without treatment. For the second objective, compounds C1 and C3 did not show significant results in the infected group without treatment. For the third objective, the mice treated with C3 and C1 reduced the global and differential cell count. The results suggest that although the evaluated compounds do not present schistosomicidal properties when placed in cercariae suspension, they can stimulate an immune reaction in snails and decrease mice's inflammatory response. In general, we can conclude that compound C1 and C3 has an anti-schistosomicidal effect both in the larval phase (miracidia) and in the adult form of the parasite.

Toxicological effects of the mixed iron oxide nanoparticle (Fe3O4 NP) on murine fibroblasts LA-9

The increase in large-scale production of magnetic nanoparticles (NP) associated with the incomplete comprehensive knowledge regarding the potential risks of their use on environmental and human health makes it necessary to study the biological effects of these particles on organisms at the cellular level. The aim of this study to examine the cellular effects on fibroblast lineage LA-9 after exposure to mixed iron oxide NP (Fe₃O₄ NP). The following analyses were performed: field emission gun-scanning electron microscopy (SEM-FEG), dynamic light scattering (DLS), zeta potential, ultraviolet/visible region spectroscopy (UV/VIS), and attenuated total reactance-Fourier transform infrared (ATR-FTIR) spectroscopy analyses for characterization of the NP. The assays included cell viability, morphology, clonogenic potential, oxidative stress as measurement of reactive oxygen species (ROS) and nitric oxide (NO) levels, cytokines quantification interleukin 6 (IL-6) and tumor necrosis factor (TNF), NP uptake, and cell death. The size of Fe₃O₄ NP was 26.3 nm when evaluated in water through DLS. Fe₃O₄ NP did not reduce fibroblast cell viability until the highest concentration tested (250 µg/ml), which showed a decrease in clonogenic potential as well as small morphological changes after exposure for 48 and 72 hr. The NP concentration of 250 µg/ml induced enhanced ROS and NO production after 24 hr treatment. The uptake assay exhibited time-dependent Fe₃O₄ NP internalization at all concentrations tested with no significant cell death. Hence, exposure of fibroblasts to Fe₃O₄ NP-induced oxidative stress but not reduced cell viability or death. However, the decrease in the clonogenic potential at the highest concentration demonstrates cytotoxic effects attributed to Fe₃O₄ NP which occurred on the 7^th day after exposure.

New Multi-Walled carbon nanotube of industrial interest induce cell death in murine fibroblast cells

The search for new nanomaterials has brought to the multifactorial industry several opportunities for use and applications for existing materials. Carbon nanotubes (CNT), for example, present excellent properties which allow us to assume a series of applications, however there is concern in the industrial scope about possible adverse health effects related to constant exposure for inhalation or direct skin contact. Thus, using cell models is the fastest and safest way to assess the effects of a new material. The aim of this study was to investigate the cytotoxic profile in LA9 murine fibroblast lineage, of a new multi-walled carbon nanotube (MWCNT) that was functionalized with tetraethylenepentamine (TEPA) to obtain better physical-chemical characteristics for industrial use. The modifications presented in the CNT cause concern, as they can change its initial characteristics, making this nanomaterial harmful. HR-TEM, FE-SEM and zeta potential were used for the characterization. Cytotoxicity and cell proliferation tests, oxidative and nitrosative stress analyzes and inflammatory cytokine assay (TNF-α) were performed. The main findings demonstrated a reduction in cell viability, increased release of intracellular ROS, accompanied by an increase in TNF-α, indicating an important inflammatory profile. Confirmation of the data was performed by flow cytometry and ImageXpress with apoptosis/necrosis markers. These data provide initial evidence that OCNT-TEPA has a cytotoxic profile dependent on the concentration of LA9 fibroblasts, since there was an increase in free radicals, inflammation induction and cell death, suggesting that continuous exposure to this nanoparticle can cause damage to different tissues in the organism.

Investigating Immunization With Nucleotide Enzymes of Schistosoma mansoni: Nucleoside Diphosphate Kinase and Adenylosuccinate Lyase as New Antigenic Targets Against Schistosomiasis

Schistosomiasis, caused by Schistosoma mansoni trematode worm, affects more than 1.5 million people in Brazil. The current treatment consists in the administration of Praziquantel, the only medicine used for treatment for more than 40 years. Some of the limitations of this drug consist in its inactivity against schistosomula and parasite eggs, the appearance of resistant strains and non-prevention against reinfection. Thus, the objective of this study was to evaluate the effect of immunization with recombinant functional enzymes of the purine salvage pathway of S. mansoni, Nucleoside Diphosphate Kinase (NDPK) and Adenylosuccinate Lyase (ADSL), to evaluate the host immune response, as well as the parasite load after vaccination. For this, Balb/c mice were divided into 5 groups: control (uninfected and untreated), non-immunized/infected, NDPK infected, ADSL infected, and NDPK + ADSL infected. Immunized groups received three enzyme dosages, with a 15-day interval between each dose, and after 15 days of the last application the animals were infected with 80 cercariae of S. mansoni. On the 47th day after the infection, fecal eggs were counted and, on the 48th day after the infection, the evaluation of leukocyte response, parasite load, antibody production, cytokines quantification, and histopathological analysis were performed. The results showed that immunizations with NDPK, ADSL or NDPK + ADSL promoted a discreet reduction in eosinophil counts in lavage of peritoneal cavity. All immunized animals showed increased production and secretion of IgG1, IgG2a, and IgE antibodies. Increased production of IL-4 was observed in the group immunized with the combination of both enzymes (NDPK + ADSL). In addition, in all immunized groups there were reductions in egg counts in the liver and intestine, such as reductions in liver granulomas. Thus, we suggest that immunizations with these enzymes could contribute to the reduction of schistosomiasis transmission, besides being important in immunopathogenesis control of the disease.

Robust Phenotypic Activation of Eosinophils during Experimental Toxocara canis Infection

Eosinophils are multifunctional cells that have cytotoxic proinflammatory activities and stimulate CD4⁺ T-cells in experimental models of allergy and parasitic infections. Eosinophils, when exposed to antigens, are activated, expressing the CD38/CD69 molecules and exhibited increased expression of major histocompatibility complex (MHC-II), CD80 and CD86, suggesting they play a role upon Toxocara canis antigen stimulation. In the present study, we evaluated the profile of eosinophils using conventional and image flow cytometry upon experimental T. canis infection. T. canis antigens induced a robust activation on this subset, contributing to the immune responses elicited in the experimental model for T. canis-associated visceral larva migrans syndrome. Data analysis demonstrated that, during murine T. canis infection, eosinophils from peripheral blood, spleen, and bone marrow presented upregulated expression of CD69/MHC-II/CD80/CD86. As opposed to splenic and bone marrow eosinophils, circulating eosinophils had increased expression of activation markers upon T. canis infection. The enhanced connectivity between eosinophils and T-cells in T. canis-infected mice in all three compartments (peripheral blood, spleen, and bone marrow) also supports the hypothesis that eosinophils may adopt a role during T. canis infection. Moreover, in vitro T. canis antigen stimulation resulted in activation and upregulation of co-stimulatory-related molecules by bone marrow-derived eosinophils. Our findings are evidence of activation and upregulation of important activation and co-stimulatory-related molecules in eosinophils and suggest a reshape of activation hierarchy toward eosinophils during experimental T. canis infection.