Early preclinical screening using zebrafish (Danio rerio) reveals the safety of the candidate anti-inflammatory therapeutic agent TnP

Antinociceptive effect of Nephelium lappaceum L. fruit peel and the participation of nitric oxide, opioid receptors, and ATP-sensitive potassium channels

Introduction: Nephelium lappaceum L. (Sapindaceae) is a plant known as rambutan. It is used for various purposes in traditional medicine. Objective: We aimed to evaluate the antinociceptive effects of the ethanol extract of the fruit peel of N. lappaceum (EENL), the mechanisms involved in these effects, and the acute toxicity in zebrafish. Methods: We performed chromatography coupled to mass spectrometry, acute toxicity assay in zebrafish, and evaluation in mice submitted to models of nociception and locomotor activity. Results: We identified (epi)-catechin, procyanidin B, and ellagic acid and its derivatives in EENL. We did not find any toxicity in zebrafish embryos incubated with EENL. The locomotor activity of mice submitted to oral pretreatment with EENL was not changed, but it reduced the abdominal constrictions induced by acetic acid, the licking/biting time in both the first and second phase of formalin testing and capsaicin testing, and carrageenan-induced paw mechanical allodynia. Oral pretreatment with EENL increased latency time in the hot plate test. This antinociceptive effect was significantly reversed by naloxone, L-arginine, and glibenclamide respectively showing the participation of opioid receptors, nitric oxide, and KATP channels as mediators of EENL-induced antinociception. Conclusion: EENL causes antinociception with the participation of opioid receptors, nitric oxide, and KATP channels, and is not toxic to zebrafish.

Assessing Drug Administration Techniques in Zebrafish Models of Neurological Disease

Neurological diseases, including neurodegenerative and neurodevelopmental disorders, affect nearly one in six of the world's population. The burden of the resulting deaths and disability is set to rise during the next few decades as a consequence of an aging population. To address this, zebrafish have become increasingly prominent as a model for studying human neurological diseases and exploring potential therapies. Zebrafish offer numerous benefits, such as genetic homology and brain similarities, complementing traditional mammalian models and serving as a valuable tool for genetic screening and drug discovery. In this comprehensive review, we highlight various drug delivery techniques and systems employed for therapeutic interventions of neurological diseases in zebrafish, and evaluate their suitability. We also discuss the challenges encountered during this process and present potential advancements in innovative techniques.

"Half-Sandwich" Ruthenium Complexes with Alizarin as Anticancer Agents: In Vitro and In Vivo Studies

Upon exploration of the chemistry of the combination of ruthenium/arene with anthraquinone alizarin (L), three new complexes with the general formulas [Ru(L)Cl(η⁶-p-cymene)] (C1), [Ru(L)(η⁶-p-cymene)(PPh₃)]PF₆ (C2), and [Ru(L)(η⁶-p-cymene)(PEt₃)]PF₆ (C3) were synthesized and characterized using spectroscopic techniques (mass, IR, and 1D and 2D NMR), molar conductivity, elemental analysis, and X-ray diffraction. Complex C1 exhibited fluorescence, such as free alizarin, while in C2 and C3, the emission was probably quenched by monophosphines and the crystallographic data showed that hydrophobic interactions are predominant in intermolecular contacts. The cytotoxicity of the complexes was evaluated in the MDA-MB-231 (triple-negative breast cancer), MCF-7 (breast cancer), and A549 (lung) tumor cell lines and MCF-10A (breast) and MRC-5 (lung) nontumor cell lines. Complexes C1 and C2 were more selective to the breast tumor cell lines, and C2 was the most cytotoxic (IC₅₀ = 6.5 μM for MDA-MB-231). In addition, compound C1 performs a covalent interaction with DNA, while C2 and C3 present only weak interactions; however, internalization studies by flow cytometry and confocal microscopy showed that complex C1 does not accumulate in viable MDA-MB-231 cells and is detected in the cytoplasm only after cell permeabilization. Investigations of the mechanism of action of the complexes indicate that C2 promotes cell cycle arrest in the Sub-G₁ phase in MDA-MB-231, inhibits its colony formation, and has a possible antimetastatic action, impeding cell migration in the wound-healing experiment (13% of wound healing in 24 h). The in vivo toxicological experiments with zebrafish indicate that C1 and C3 exhibit the most zebrafish embryo developmental toxicity (inhibition of spontaneous movements and heartbeats), while C2, the most promising anticancer drug in the in vitro preclinical tests, revealed the lowest toxicity in in vivo preclinical screening.

The Anti-Inflammatory Peptide TnP Is a Candidate Molecule for Asthma Treatment

Asthma is the most common chronic lung disease, with increasing morbidity and mortality worldwide. Accumulation of peribronchial leukocytes is the hallmark of asthma, in particular, eosinophils, which have been reported as the primary cell associated with the induction of airway hyperresponsiveness. Continued exacerbation and accumulation of other leukocytes, such as neutrophils, Th1, and Th17 cells correlate with many of the long-term effects of asthma, such as airway remodeling. We have patented the TnP family of synthetic cyclic peptides, which is in the preclinical phase of developmental studies for chronic inflammatory diseases. The aim of this work was to investigate whether TnP could show anti-inflammatory activity in a murine model of asthma that includes a mixed phenotype of eosinophilic and neutrophilic inflammation. For this, Balb/c mice, sensitized with OVA and exposed to 1% challenge with OVA aerosol, were submitted to prophylactic treatment, receiving TnP at 0.3 mg/kg orally, 1 h before each challenge. We found that sensitized mice challenged with OVA and treated with TnP showed no airway hyperreactivity or lung remodeling. TnP acts systemically in secondary lymphoid organs and locally in the lung, inhibiting the production of Th2/Th17 cytokines. Furthermore, TnP prevented the infiltration of eosinophils and neutrophils in the BAL and lung tissue, inhibited the production of IgE/IgG1, prevented hyperplasia of mucus-producing cells, and decreased the thickening and deposition of sub-epithelial collagen. Our results showed TnP as a candidate molecule for the treatment of airway remodeling associated with inflammatory diseases, such as asthma.

Shedding Light on the Drug-Target Prediction of the Anti-Inflammatory Peptide TnP with Bioinformatics Tools

Peptide–protein interactions are involved in various fundamental cellular functions, and their identification is crucial for designing efficacious peptide therapeutics. Drug–target interactions can be inferred by in silico prediction using bioinformatics and computational tools. We patented the TnP family of synthetic cyclic peptides, which is in the preclinical stage of developmental studies for chronic inflammatory diseases such as multiple sclerosis. In an experimental autoimmune enceph-alomyelitis model, we found that TnP controls neuroinflammation and prevents demyelination due to its capacity to cross the blood–brain barrier and to act in the central nervous system blocking the migration of inflammatory cells responsible for neuronal degeneration. Therefore, the identification of potential targets for TnP is the objective of this research. In this study, we used bioinformatics and computational approaches, as well as bioactivity databases, to evaluate TnP–target prediction for proteins that were not experimentally tested, specifically predicting the 3D structure of TnP and its biochemical characteristics, TnP–target protein binding and docking properties, and dynamics of TnP competition for the protein/receptor complex interaction, construction of a network of con-nectivity and interactions between molecules as a result of TnP blockade, and analysis of similarities with bioactive molecules. Based on our results, integrins were identified as important key proteins and considered responsible to regulate TnP-governed pharmacological effects. This comprehensive in silico study will help to understand how TnP induces its anti-inflammatory effects and will also facilitate the identification of possible side effects, as it shows its link with multiple biologically important targets in humans.

TnP Peptide Suppresses Experimental Autoimmune Encephalomyelitis (EAE) in a Preclinical Mouse Model

TnP is a family of patented synthetic peptides which is in a preclinical development stage with valuable potential therapeutic indication for multiple sclerosis (MS), an autoimmune demyelinating disease of the central nervous system (CNS). The use of a preclinical animal model, such as experimental autoimmune encephalomyelitis (EAE) has deepened our knowledge of the immunomodulatory functions of TnP as a drug. We have shown that TnP possesses a disease suppressive function in EAE, ameliorating disease severity by 40% and suppressing the accumulation of T helper (Th)1- and Th17-producing lymphocytes (by 55% and 60%, respectively) in CNS along with activated microglia/macrophages populations (by 33% and 50%, respectively), and also conferred a protective effect anticipating the remyelination process to day 66 compared to day 83 of untreated cuprizone-mice. Here we expanded our knowledge about its effects compared with current first-line disease-modifying therapies (DMT). We demonstrated that prophylactic treatment with TnP generated similar protection to betaseron (30%) or was more effective than glatiramer (44% versus 6%) or fingolimod (50% versus 19%) against the development of clinical symptoms. Although TnP controlled the leukocyte infiltration (87% versus 82%) into demyelinated areas of the spinal cord in the same way as betaseron and fingolimod, it was more effective (72% to 78% decrease) in the long-term control of neuronal degeneration compared to them. Also, when compared to glatiramer, TnP was more efficient in reversing leukocytes infiltration into the spinal cord (55% versus 24%), as well as induced a higher percentage of regulatory cells in spleen (2.9-fold versus 2.3-fold increase over vehicle-treated EAE mice) an in the spinal cord (8-fold versus 6-fold increase over vehicle-treated EAE mice). This specialized TnP profile for inducing immune tolerance and neuronal regeneration has significant therapeutic potential for the treatment of MS and other autoimmune diseases.

Zebrafish Beyond the Bench: The 'Plataforma Zebrafish Open Doors' Programme

The Butantan Institute is a pioneering Brazilian health sciences institution, which also houses a large science park with museums that contribute to ongoing science education for schools and the wider community. In recent years, as part of Butantan Institute's Plataforma Zebrafish™, zebrafish embryos have been used for the dissemination of scientific knowledge during on-site events and as part of outreach campaigns to non-scientific audiences, mostly children. The aim of this work is mainly to demystify the activities of the scientific researcher, highlight the role of science in the furthering of knowledge, and increase public interest and confidence in science. In this article, the Institute's 'Plataforma Zebrafish Open Doors' programme is described, which offered guided tours of the laboratory facilities. The tours gave visitors the opportunity to observe zebrafish research and embryo development, and to use the knowledge gained from this experience as a framework for understanding fundamental ethical issues. During the 2-day event, around 800 visitors (most of them school-age children) attended. Together with the guided tours, our experience of outreach offered meaningful opportunities to bring children and members of the public closer to science and 'real-life' scientists, hopefully inspiring and encouraging the next generation of scientists. It also gave the scientists an opportunity to engage more closely with wider society. We believe that these activities also substantially contribute to the wider dissemination of relevant experimental results that have been obtained with public funding and that impact society in general.

In Silico Target Prediction of Overexpressed microRNAs from LPS-Challenged Zebrafish (Danio rerio) Treated with the Novel Anti-Inflammatory Peptide TnP

miRNAs regulate gene expression post-transcriptionally in various processes, e.g., immunity, development, and diseases. Since their experimental analysis is complex, in silico target prediction is important for directing investigations. TnP is a candidate peptide for anti-inflammatory therapy, first discovered in the venom of Thalassophryne nattereri, which led to miRNAs overexpression in LPS-inflamed zebrafish post-treatment. This work aimed to predict miR-21, miR-122, miR-731, and miR-26 targets using overlapped results of DIANA microT-CDS and TargetScanFish software. This study described 513 miRNAs targets using highly specific thresholds. Using Gene Ontology over-representation analysis, we identified their main roles in regulating gene expression, neurogenesis, DNA-binding, transcription regulation, immune system process, and inflammatory response. miRNAs act in post-transcriptional regulation, but we revealed that their targets are strongly related to expression regulation at the transcriptional level, e.g., transcription factors proteins. A few predicted genes participated concomitantly in many biological processes and molecular functions, such as foxo3a, rbpjb, rxrbb, tyrobp, hes6, zic5, smad1, e2f7, and npas4a. Others were particularly involved in innate immunity regulation: il17a/f2, pik3r3b, and nlrc6. Together, these findings not only provide new insights into the miRNAs mode of action but also raise hope for TnP therapy and may direct future experimental investigations.

Knockdown of miR-26a in zebrafish leads to impairment of the anti-inflammatory function of TnP in the control of neutrophilia

Our recent data show the valuable potential of TnP for the development of a new and safe anti-inflammatory drug due to its ability to control the traffic and activation of leukocytes in response to inflammation. Although there is considerable knowledge surrounding the cellular mechanisms of TnP, less is known about the mechanistic molecular role of TnP underlying its immunomodulatory functions. Here, we conducted investigations to identify whether miRNAs could be one of the molecular bases of the therapeutic effect of TnP. Using a zebrafish model of neutrophilic inflammation with a combination of genetic gain- and loss-of-function approaches, we showed that TnP treatment was followed by up-regulation of only four known miRNAs, and mature dre-miR-26a-1, herein referred just as miR-26a was the first most highly expressed. The knockdown of miR-26a ubiquitously resulted in a significant reduction of miR-26a in embryos, accompanied by impaired TnP immunomodulatory function observed by the loss of the control of the removal of neutrophils in response to inflammation, while the overexpression increased the inhibition of neutrophilic inflammation promoted by TnP. The striking importance of miR-26a was confirmed when rescue strategies were used (morpholino and mimic combination). Our results identified miR-26a as an essential molecular regulator of the therapeutic action of TnP, and suggest that miR-26a or its targets could be used as promising therapeutic candidates for enhancing the resolution of inflammation.