Equine large intestinal microbiota in the steady-state, and over the course of acute and chronic inflammatory conditions

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dc.contributor.authorWalshe, Nicola-
dc.date.copyright2022 the Authoren_US
dc.description.abstractBiodiversity is the foundation on which ecosystems are built and is crucial to the sustainability of health and wellbeing of all species, yet through centuries of development and progression the diversity within ecosystems has been degraded, leading to downstream unforeseen consequences. However, through a rise in availability and sophistication of diagnostics and an awareness of the link between diversity and health via the “hygiene hypothesis”, research into biospheres such as the intestinal ecological environment is gaining momentum. To combat the rise in lifestyle and immune mediated disease seen in the developed world, there is a rapidly growing repertoire of literature around the importance not only of gut microbial diversity but also of coevolutionary intestinal inhabitants such as helminths. In line with this in Chapter 1 we investigate the literature regarding the influence of intestinal microbiota and gastrointestinal helminths in horses and in other species in relation to acute and chronic inflammatory disorders. Chapter 2 examines the effects of anthelmintic-induced disruption of the helminth community on the host immune response and faecal microbiota in horses; the results demonstrate that removal of helminths through anthelmintic treatment induces a change in the faecal microbiota, with a decrease seen in both alpha-diversity and beta-diversity post-treatment, which subsequently resolved 14 days later. These changes correspond with both a local and systemic inflammatory response. In Chapter 3, we expand our analysis into the effects of acute helminth disease processes with an investigation of an outbreak of acute larval cyathostominosis (ALC) in a group of horses analysing the clinicopathological parameters and associated faecal microbiota changes. Here, we outline the main clinicopathological findings of ALC adding to the literature regarding ante-mortem diagnosis of the disease. We show that the severe inflammatory intestinal response is accompanied by decreased alpha-diversity of the faecal microbiota and greater relative abundance of possible pathobionts. Our findings suggest that the relationship between intestinal microbiota, host immunity and cyathostomins could play a role in the initiation and propagation of acute intestinal disease processes. In Chapter 4, to assess the effectiveness of a weight loss intervention on overweight horses regarding gut health, we use a multiomics approach including analysis of the faecal microbiota and metabolome. The treatment group lost weight and had significant phenotypic changes; however, there was no significant difference between the faecal microbiota or metabolome when compared to the control group. Notably, there was an increase in alpha-diversity in the treatment group from the start to end of the study, with an increase in abundance of taxa associated with gut health. These findings lay the foundation for further investigation into the biomarkers associated with improved gut health through interventions in chronic inflammatory diseases and associated disorders such as obesity and equine metabolic syndrome. Chapter 5 synthesises and presents the results of the experimental Chapters in context. Through the exploration of the importance of intestinal equilibrium in the steady-state, acute inflammatory disease and chronic inflammatory disorders, we offer insights into the mechanistic inter-relationships between the host and intestinal biosphere inhabitants whilst also outlining the research gaps in the equine literature. Moreover, we highlight the possible advantages of using horses, who rely so heavily on the hindgut for both nutrition and health whilst harbouring a resident helminth population, as a model for research into this complex ecosystem in health and disease.en_US
dc.publisherUniversity College Dublin. School of Veterinary Medicineen_US
dc.titleEquine large intestinal microbiota in the steady-state, and over the course of acute and chronic inflammatory conditionsen_US
dc.typeDoctoral Thesisen_US
dc.statusPeer revieweden_US
dc.description.admin2022-06-21 JG: Signature removed from PDFen_US
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