Biology subjects

Daunt, C.

Publications and source records attributed to Daunt, C..

3 recordsLinked to original sources

bioRxiv2025

Screening of the Pathogen box reveals novel anti blood-feeding compounds

Soil-transmitted helminth (STH) infections such as Necator americanus infect millions globally, and are a major cause of anemia and developmental stunting in low and middle income countries. Blood-feeding hookworms in particular rely on the digestion of host erythrocytes for nutrition and therefore detoxify heme as a byproduct of their parasitism. This dependency on blood feeding and subsequent detoxification renders this pathway as a vulnerable target for therapeutic intervention, particularly as it is the cause of morbidity in those infected. Here we described the continued development and application of a high-throughput in vitro assay using the so-called rodent hookworm Nippostrongylus brasiliensis, a model that shares key traits with N. americanus including blood feeding and hemozoin-like pigment formation. We optimized a fluorescence-based screening cascade to utilise GelGreen as a cost-effective viability stain and screened 400 compounds from the MMV Pathogen Box. Multiple compounds displayed enhanced activity in the presence of blood, suggesting interference with blood-feeding or blood-feeding-induced development. Five hits were selected for further validation, and as proof-of-principle of this screening cascade, all five were well tolerated in vivo at low doses in a murine model. This study therefore demonstrates this method can be used as a tractable and biologically relevant screening approach to identify compounds active against blood-feeding nematodes. Future work can further develop such compounds into lead drug candidates, and be leveraged for comparative parasitology approaches to identify pan-anthelmintic drugs.

microbiology↗

bioRxiv2024

Holding glycolysis in check though Alox15 activity is required for macrophage M2 commitment and function in tissue repair and anti-helminth immunity.

Macrophage polarization by type-2 cytokines is central to anti-helminth immunity and tissue repair. While some hallmark changes in macrophages are well-characterized and associated with protection against helminths, it is still unclear how macrophages exert their anti-helminth effects. In this context, we investigated Arachidonate 15-lipoxygenase (Alox15), a lipoxygenase well known for its role in macrophage polarization in the context of metabolic diseases, and a hallmark of type-2 macrophage (M2) human polarization. We show that in the absence of Alox15, M2 cannot trap and kill helminths. Surprisingly, expression of M2 markers was normal despite a loss of function. Instead, we found a concomitant increase in pro-inflammatory responses due to an uncontrolled activation of glycolysis. We further show that activation of Peroxisome proliferator-activated receptor-delta (PPAR-{delta}) by lipids downstream of Docosapentaenoic acid (DPA) can restore normal glycolysis control, highlighting a novel role for lipids in the fine-tuning of the metabolic support required for optimal macrophage polarization.

immunology↗

bioRxiv2023

Helminth infection driven gastrointestinal hypermotility is independent of eosinophils and mediated by alterations in smooth muscle instead of enteric neurons

Intestinal helminth infection triggers a type 2 immune response that promotes a weep-and sweep response characterised by increased mucus secretion and intestinal hypermotility, which function to dislodge the worm from its intestinal habitat. Recent studies have discovered that several other pathogens cause intestinal dysmotility through major alterations to the immune and enteric nervous systems (ENS), and their interactions, within the gastrointestinal tract. However, the involvement of these systems has not been investigated for helminth infections. Eosinophils represent a key cell type recruited by the type 2 immune response and alter intestinal motility under steady-state conditions. Our study aimed to investigate whether intestinal dysmotility driven by murine hookworm, Nippostrongylus brasiliensis, infection involves eosinophils and how the ENS and smooth muscles of the gut are impacted. Eosinophil deficiency did not influence helminth-induced intestinal hypermotility and hypermotility did not involve gross structural or functional changes to the ENS. Hypermotility was instead associated with a dramatic increase in smooth muscle thickness and contractility. In summary our data indicate that, in contrast to other pathogens, helminth-induced intestinal hypermotility is driven by largely by myogenic, rather than neurogenic, alterations with such changes occurring independently of eosinophils. (<300 words) Author SummaryIntestinal helminth infection is a global threat to those living in poverty without adequate sanitation. Expulsion of intestinal worms is driven by a host type 2 immune response, characterised by increased eosinophils, that results in the intestinal hypermotility and mucus secretion that dislodge the worm from its luminal habitat. Intestinal motility is largely controlled by the local enteric nervous system (ENS) and can be regulated by close interactions between neurons and intestinal immune cells. Utilising Nippostrongylus brasiliensis as a model of murine hookworm infection, we investigated the contribution of the ENS and eosinophils to intestinal hypermotility and worm expulsion. Despite the critical role of the ENS in regulating typical intestinal function, very little alteration to ENS structure or function was observed following N. brasiliensis infection. Instead, infected animals displayed dramatically increased smooth muscle thickness and contractile strength. Neither helminth-induced intestinal hypermotility nor altered smooth muscle morphology required eosinophils. Our findings reveal that, in contrast to other intestinal pathogens, myogenic rather than neurogenic alterations drive small intestinal hypermotility and pathogen expulsion following hookworm infection. (<200 words)

immunology↗