Identification of small molecule enzyme inhibitors as broad-spectrum anthelmintics

Abstract

Targeting chokepoint enzymes in metabolic pathways has led to new drugs for cancers, autoimmune disorders and infectious diseases. This is also a cornerstone approach for discovery and development of anthelmintics against nematode and flatworm parasites. Here, we performed omics-driven knowledge-based identification of chokepoint enzymes as anthelmintic targets. We prioritized 10 of 186 phylogenetically conserved chokepoint enzymes and undertook a target class repurposing approach to test and identify new small molecules with broad spectrum anthelmintic activity. First, we identified and tested 94 commercially available compounds using an in vitro phenotypic assay, and discovered 11 hits that inhibited nematode motility. Based on these findings, we performed chemogenomic screening and tested 32 additional compounds, identifying 6 more active hits. Overall, 6 intestinal (single-species), 5 potential pan-intestinal (whipworm and hookworm) and 6 pan-Phylum Nematoda (intestinal and filarial species) small molecule inhibitors were identified, including multiple azoles, Tadalafil and Torin-1. The active hit compounds targeted three different target classes in humans, which are involved in various pathways, including carbohydrate, amino acid and nucleotide metabolism. Last, using representative inhibitors from each target class, we demonstrated in vivo efficacy characterized by negative effects on parasite fecundity in hamsters infected with hookworms.

An Integrated Approach to Identify New Anti-Filarial Leads to Treat River Blindness, a Neglected Tropical Disease

“…Azoles have also been reported to inhibit other crucial genes like P-gp, multiple CYP proteins, certain ion channels and receptors, thromboxane synthase (an inflammation mediator), FYN (a Src family tyrosine kinase oncogene), heme oxygenase (heme metabolism; maintaining homeostasis under oxidative and other stresses), Indoleamine 2,3-dioxygenase (heme containing immunomodulator), etc., [ 87 , 88 ]. They have also been identified in our previous work as potential broad-spectrum anthelmintics [ 89 ] based on their known activity against malate dehydrogenase (MDH) [ 90 , 91 ]. One concern is that some of these drugs may exhibit poor water solubility and oral bioavailability and may also have unacceptable side-effects on oral administration.…”

Rapid determination of nematode cell and organ susceptibility to toxic treatments

“…However, the limited selection of efficacious anthelmintics and emerging pathogen resistance to anthelmintics ( Sangster et al, 2018 ) identifies a need to expand the selection of drugs available for therapy and control of parasitic nematodes. A surge in research to increase the limited arsenal of available anthelmintic compounds has stemmed from several advances, including expanding parasite multi-omics resources, technological advances in biologic screening methods, access to expanding small molecule inhibitor libraries, and enhanced computational methods that integrate biologic data with large knowledge bases related to both drug and inhibitor compounds (examples include ( Taylor et al, 2013 ; Tyagi et al, 2018 ; Tyagi et al, 2019 ; Jasmer et al, 2020 )). These omics-driven approaches have proven quite effective in identifying small molecule inhibitors that are toxic to parasitic nematodes and have multiple applications to anthelmintic research.…”

De novo identification of toxicants that cause irreparable damage to parasitic nematode intestinal cells

“…Similar approach at a smaller scale or aimed at specific processes has been successfully applied before (e.g. [38, 45]), but in this case our focus was on a single tissue, highlighting this computational approach’s flexibility when studying specific tissues or pathogens or other systems of interest. The prioritization includes criteria to select targets based on orthology (conserved across parasitic nematode species), intestinal proteomic detection (providing evidence that the gene target is active and produces proteins in the worm intestine), high gene transcription levels in the intestine across several nematode species (providing supporting evidence of cross-species conserved intestinal function), and knowledge-based evidence of the gene’s biological functions (providing evidence that inhibiting the target could be lethal in the nematodes based on RNAi phenotype of orthologous targets in C. elegans ).…”