Plasma proteome responses in zebrafish following λ-carrageenan-Induced inflammation are mediated by PMN leukocytes and correlate highly with their human counterparts.

Regulation of inflammation is a critical process for maintaining physiological homeostasis. The λ-carrageenan (λ-CGN) is a mucopolysaccharide extracted from the cell wall of red algae (Chondrus crispus) capable of inducing acute intestinal inflammation, which is translated into the production of acute phase reactants secreted into the blood circulation. However, the associated mechanisms in vertebrates are not well understood. Here, we investigated the crucial factors behind the inflammatory milieu of λ-CGN-mediated inflammation administered at 0, 1.75, and 3.5% (v/w) by i.p. injection into the peritoneal cavity of adult zebrafish (ZF) (Danio rerio). We found that polymorphonuclear leukocytes (neutrophils) and lymphocytes infiltrating the ZF peritoneal cavity had short-term persistence. Nevertheless, they generate a strong pattern of inflammation that affects systemically and is enough to produce edema in the cavity. Consistent with these findings, cell infiltration, which causes notable tissue changes, resulted in the overexpression of several acute inflammatory markers at the protein level. Using reversed-phase high-performance liquid chromatography followed by a hybrid linear ion-trap mass spectrometry shotgun proteomic approach, we identified 2938 plasma proteins among the animals injected with PBS and 3.5% λ-CGN. First, the bioinformatic analysis revealed the composition of the plasma proteome. Interestingly, 72 commonly expressed proteins were recorded among the treated and control groups, but, surprisingly, 2830 novel proteins were differentially expressed exclusively in the λ-CGN-induced group. Furthermore, from the commonly expressed proteins, compared to the control group 62 proteins got a significant (p < 0.05) upregulation in the λ-CGN-treated group, while the remaining ten proteins were downregulated. Next, we obtained the major protein-protein interaction networks between hub protein clusters in the blood plasma of the λ-CGN induced group. Moreover, to understand the molecular underpinnings of these effects based on the unveiled protein sets, we performed a bioinformatic structural similarity analysis and generated overlapping 3D reconstructions between ZF and humans during acute inflammation. Biological pathway analysis pointed to the activation and abundance of diverse classical immune and acute phase reactants, several catalytic enzymes, and varied proteins supporting the immune response. Together, this information can be used for testing and finding novel pharmacological targets to treat human intestinal inflammatory diseases.

Zebrafish as a model to study inflammation: A tool for drug discovery.

This study aims to demonstrate the applicability and importance of zebrafish (Danio rerio) model to study acute and chronic inflammatory responses induced by different stimuli: carrageenan phlogogen (nonimmune); acute infection by bacteria (immune); foreign body reaction (chronic inflammation by round glass coverslip implantation); reaction induced by xenotransplantation. In addition to the advantages of presenting low breeding cost, high prolificity, transparent embryos, high number of individuals belonging to the same spawning and high genetic similarity that favor translational responses to vertebrate organisms like humans, zebrafish proved to be an excellent tool, allowing the evaluation of edema formation, accumulation of inflammatory cells in the exudate, mediators, signaling pathways, gene expression and production of specific proteins. Our studies demonstrated the versatility of fish models to investigate the inflammatory response and its pathophysiology, essential for the successful development of studies to discover innovative pharmacological strategies.

Preclinical Gold Complexes as Oral Drug Candidates to Treat Leishmaniasis Are Potent Trypanothione Reductase Inhibitors.

The drugs currently used to treat leishmaniases have limitations concerning cost, efficacy, and safety, making the search for new therapeutic approaches urgent. We found that the gold(I)-derived complexes were active against L. infantum and L. braziliensis intracellular amastigotes with IC50 values ranging from 0.5 to 5.5 µM. All gold(I) complexes were potent inhibitors of trypanothione reductase (TR), with enzyme IC50 values ranging from 1 to 7.8 µM. Triethylphosphine-derived complexes enhanced reactive oxygen species (ROS) production and decreased mitochondrial respiration after 2 h of exposure, indicating that gold(I) complexes cause oxidative stress by direct ROS production, by causing mitochondrial damage or by impairing TR activity and thus accumulating ROS. There was no cross-resistance to antimony; in fact, SbR (antimony-resistant mutants) strains were hypersensitive to some of the complexes. BALB/c mice infected with luciferase-expressing L. braziliensis or L. amazonensis and treated orally with 12.5 mg/kg/day of AdT Et (3) or AdO Et (4) presented reduced lesion size and parasite burden, as revealed by bioimaging. The combination of (3) and miltefosine allowed for a 50% reduction in miltefosine treatment time. Complexes 3 and 4 presented favorable pharmacokinetic and toxicity profiles that encourage further drug development studies. Gold(I) complexes are promising antileishmanial agents, with a potential for therapeutic use, including in leishmaniasis caused by antimony-resistant parasites.

Acute-phase proteins during inflammatory reaction by bacterial infection: fish-model

Acute-phase protein (APPs) serum levels have been studied in many human diseases, and their components contribute to host defense during the evolution of infectious diseases by acting as part of the innate immune system. Based on the importance of establishing new experimental models, the present investigation evaluated the modulation of APPs following inflammatory stimulus by the inoculation of Aeromonas hydrophila in tilapias. Fish were sampled 6 and 24 hours post-infection. Tilapias presented increase of positive APPs such as ceruloplasmin, haptoglobin, alpha-2-macroglobulin and complement C3, as well as decrease of negative APPs such as albumin and transferrin. The protein response of tilapias during the course of bacterial infection showed correlation with the kinetics of cellular accumulation in the inflamed focus with significant increase of granulocytes, thrombocytes, lymphocytes and macrophages. However, granulocytes were the predominant cells, associated with increment in the reactive oxygen species (ROS) production. Showing responses similar to those observed in humans, the modulation of APPs and the kinetics of cellular accumulation in the exudate demonstrate the feasibility of this alternative experimental model for advances and studies to understand changes in pathophysiological mechanisms of acute inflammatory reaction due to bacterial infection.

Efficacy of Meglumine Antimoniate in a Low Polymerization State Orally Administered in a Murine Model of Visceral Leishmaniasis.

Progress toward the improvement of meglumine antimoniate (MA), commercially known as Glucantime, a highly effective but also toxic antileishmanial drug, has been hindered by the lack of knowledge and control of its chemical composition. Here, MA was manipulated chemically with the aim of achieving an orally effective drug. MA compounds were synthesized from either antimony pentachloride (MA-SbCl5) or potassium hexahydroxyantimonate [MA-KSb(OH)6] and prepared under a low polymerization state. These compounds were compared to Glucantime regarding chemical composition, permeation properties across a cellulose membrane and Caco-2 cell monolayer, and uptake by peritoneal macrophages. MA-SbCl5 and MA-KSb(OH)6 were characterized as less polymerized and more permeative 2:2 Sb-meglumine complexes than Glucantime, which consisted of a mixture of 2:3 and 3:3 Sb-meglumine complexes. The antileishmanial activities and hepatic uptake of all compounds were evaluated after oral administration in BALB/c mice infected with Leishmania infantum chagasi, as a model of visceral leishmaniasis (VL). The synthetic MA compounds given at 300 mg Sb/kg of body weight/12 h for 30 days significantly reduced spleen and liver parasite burdens, in contrast to those for Glucantime at the same dose. The greater activity of synthetic compounds could be attributed to their higher intestinal absorption and accumulation efficiency in the liver. MA-SbCl5 given orally was as efficacious as Glucantime by the parenteral route (80 mg Sb/kg/24 h intraperitoneally). These data taken together suggest that treatment with a less-polymerized form of MA by the oral route may be effective for the treatment of VL.

Polarity-sensitive nanocarrier for oral delivery of Sb(V) and treatment of cutaneous leishmaniasis.

There is a great need for orally active drugs for the treatment of the neglected tropical disease leishmaniasis. Amphiphilic Sb(V) complexes, such as 1:3 Sb-N-octanoyl-N-methylglucamide complex (SbL8), are promising drug candidates. It has been previously reported that SbL8 forms kinetically stabilized nanoassemblies in water and that this simple dispersion exhibits antileishmanial activity when given by oral route to a murine model of visceral leishmaniasis. The main objective of the present work was to interfere in the structural organization of these nanoassemblies so as to investigate their influence on the oral bioavailability of Sb, and ultimately, optimize an oral formulation of SbL8 for the treatment of cutaneous leishmaniasis. The structural organization of SbL8 nanoassemblies was manipulated through addition of propylene glycol (PG) to the aqueous dispersion of SbL8. The presence of 50% (v/v) PG resulted in the loss of hydrophobic microenvironment, as evidenced by fluorescence probing. However, nanostructures were still present, as demonstrated by dynamic light scattering, small-angle X-ray scattering, and atomic force microscopy (AFM). A remarkable property of these nanoassemblies, as revealed by AFM analysis, is the flexibility of their supramolecular organization, which showed changes as a function of the solvent and substrate polarities. The formulation of SbL8 in 1:1 water:PG given orally to mice promoted significantly higher and more sustained serum levels of Sb, when compared to SbL8 in water. The new formulation, when given as repeated doses (200 mg Sb/kg/day) to BALB/c mice infected with Leishmania amazonensis, was significantly more effective in reducing the lesion parasite burden, compared to SbL8 in water, and even, the conventional drug Glucantime(®) given intraperitoneally at the same dose. In conclusion, this work introduces a new concept of polarity-sensitive nanocarrier that was successfully applied to optimize an oral formulation of Sb(V) for treating cutaneous leishmaniasis.

What the Erythrocytic Nuclear Alteration Frequencies Could Tell Us about Genotoxicity and Macrophage Iron Storage?

Erythrocytic nuclear alterations have been considered as an indicative of organism's exposure to genotoxic agents. Due to their close relationship among their frequencies and DNA damages, they are considered excellent markers of exposure in eukaryotes. However, poor data has been found in literature concerning their genesis, differential occurrence and their life span. In this study, we use markers of cell viability; genotoxicity and cellular turn over in order to shed light to these events. Tilapia and their blood were exposed to cadmium in acute exposure and in vitro assays. They were analyzed using flow cytometry for oxidative stress and membrane disruption, optical microscopy for erythrocytic nuclear alteration, graphite furnace atomic absorption spectrometry for cadmium content in aquaria water, blood and cytochemical and analytical electron microscopy techniques for the hemocateretic aspects. The results showed a close relationship among the total nuclear alterations and cadmium content in the total blood and melanomacrophage centres area, mismatching reactive oxygen species and membrane damages. Moreover, nuclear alterations frequencies (vacuolated, condensed and blebbed) showed to be associated to cadmium exposure whereas others (lobed and bud) were associated to depuration period. Decrease on nuclear alterations frequencies was also associated with hemosiderin increase inside spleen and head kidney macrophages mainly during depurative processes. These data disclosure in temporal fashion the main processes that drive the nuclear alterations frequencies and their relationship with some cellular and systemic biomarkers.