Development of zebrafish demyelination model for evaluation of remyelination compounds and RORγt inhibitors

Animal model of multiple sclerosis: Experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a very complex and heterogeneous disease, with an unknown etiology and which, currently, remains incurable. For this reason, animal models are crucial to investigate this disease, which has increased in prevalence in recent years, affecting 2.8 million people worldwide, and is the leading cause of non-traumatic disability in young adults between the ages of 20-30years. Of all the models developed to replicate MS, experimental autoimmune encephalomyelitis (EAE) best reflects the autoimmune pathogenesis of MS. There are different methods to induce it, which will give rise to different types of EAE, which will vary in clinical presentation and severity. Of the EAE models, the most widespread and used is the one induced in rodents due to its advantages over other species. Likewise, EAE has become a widely used model in the development of therapies for the treatment of MS. Likewise, it is very useful to define the cellular and molecular mechanisms involved in the pathogenesis of MS and to establish therapeutic targets for this disease. For all these reasons, the EAE model plays a key role in improving the understanding of MS.

Aquatic Freshwater Vertebrate Models of Epilepsy Pathology: Past Discoveries and Future Directions for Therapeutic Discovery

Epilepsy is an international public health concern that greatly affects patients’ health and lifestyle. About 30% of patients do not respond to available therapies, making new research models important for further drug discovery. Aquatic vertebrates present a promising avenue for improved seizure drug screening and discovery. Zebrafish (Danio rerio) and African clawed frogs (Xenopus laevis and tropicalis) are increasing in popularity for seizure research due to their cost-effective housing and rearing, similar genome to humans, ease of genetic manipulation, and simplicity of drug dosing. These organisms have demonstrated utility in a variety of seizure-induction models including chemical and genetic methods. Past studies with these methods have produced promising data and generated questions for further applications of these models to promote discovery of drug-resistant seizure pathology and lead to effective treatments for these patients.

Modeling neurodegenerative disorders in zebrafish

Neurodegeneration is a major cause of Alzheimer's, Parkinson's, Huntington's, multiple and amyotrophic lateral sclerosis, pontocerebellar hypoplasia, dementia and other related brain disorders. Their complex pathogenesis commonly includes genetic and neurochemical deficits, misfolded protein toxicity, demyelination, apoptosis and mitochondrial dysfunctions. Albeit differing in specific underlying mechanisms, neurodegenerative disorders typically display evolutionarily conserved mechanisms across taxa. Here, we review the role of zebrafish models in recapitulating major human and rodent neurodegenerative conditions, demonstrating this species as a highly relevant experimental model for research on neurodegenerative diseases, and discussing how these fish models can further clarify the underlying genetic, neurochemical, neuroanatomical and behavioral pathogenic mechanisms.

Discovery of carboxyl-containing biaryl ureas as potent RORγt inverse agonists

GSK805 (1) is a potent RORγt inverse agonist, but a drawback of 1 is its low solubility, leading to a limited absorption in high doses. We have explored detailed structure-activity relationship on the amide linker, biaryl and arylsulfonyl moieties of 1 trying to improve solubility while maintaining RORγt activity. As a result, a novel series of carboxyl-containing biaryl urea derivatives was discovered as potent RORγt inverse agonists with improved drug-like properties. Compound 3i showed potent RORγt inhibitory activity and subtype selectivity with an IC₅₀ of 63.8 nM in RORγ FRET assay and 85 nM in cell-based RORγ-GAL4 promotor reporter assay. Reasonable inhibitory activity of 3i was also achieved in mouse Th17 cell differentiation assay (76% inhibition at 0.3 μM). Moreover, 3i had greatly improved aqueous solubility at pH 7.4 compared to 1, exhibited decent mouse PK profile and demonstrated some in vivo efficacy in an imiquimod-induced psoriasis mice model.