Host-microbiota interactions underlying functional gastrointestinal disorders and the impact of gold kiwifruit consumption : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Albany, Manawatū, Palmerston North, New Zealand

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dc.confidentialEmbargo : No
dc.contributor.advisorMcNabb, Warren
dc.contributor.authorCarco, Caterina
dc.date.accessioned2023-11-17T01:09:20Z
dc.date.available2023-11-17T01:09:20Z
dc.date.issued2023-05-18
dc.description.abstractThe microbial ecosystem exists in a mutualistic relationship with its host, contributing to a healthy gastrointestinal tract. Growing evidence supports the role of microbial-immune interactions in functional gastrointestinal disorders (FGIDs), including irritable bowel syndrome (IBS). However, these mechanisms are poorly understood. It has been hypothesised that taxonomic and gene abundance in the faecal microbiota and gene expression of peripheral blood mononuclear cells (PBMCs) could discriminate FGID subtypes (functional constipation (FC), IBS constipation, functional diarrhoea (FD), IBS diarrhoea) from each other and healthy subjects (controls). A second hypothesis was that consuming two gold kiwifruit daily for four weeks had a different effect on the microbial composition and gene abundance than psyllium in constipation predominant FGID subjects or controls. A systems biology approach was used to address these hypotheses. Different microbial compositional and gene abundance profiles were associated with constipation and/or diarrhoea, particularly facultative anaerobes and obligate fermenters, and genes related to tyrosine metabolism, secretion systems and micronutrient utilisation. Differentially PBMC expressed immunoglobulin variable domain genes were shared among FGIDs, except for IBS constipation. Increased expression levels of interferon-induced genes and those linked to the complement system and platelet functions characterised the immune signature of functional constipation. Increased expression levels of immunoglobulin variable domain associated with immunoglobulin E/G receptor-mediated pathways characterised the immune signature of IBS diarrhoea and FD. Further analyses showed that computationally selected microbial, immune gene and symptomatic variables were associated with constipation or diarrhoea predominant FGIDs, and that symptoms remain the best way to discriminate among FGIDs or controls than PBMC genes or microbial taxa except for FC, which was best discriminated from other FGIDs or controls by selected PBMC genes. Eggerthella and Bacteroides were the only genera that differed between subjects consuming gold kiwifruit or psyllium or between each intervention compared to pre-intervention levels, regardless of the digestive health status of the subjects. This PhD thesis presents novel insights into the host-microbiota interactions underlying FGIDs and the microbiota responses to daily consumption of two gold kiwifruit over four weeks in constipation predominant FGID subjects. The knowledge generated can be used for future research on food-based treatments supporting gastrointestinal health and comfort.en
dc.identifier.urihttps://mro.massey.ac.nz/handle/10179/69101
dc.publisherMassey Universityen
dc.rightsThe Authoren
dc.subjectGastrointestinal systemen
dc.subjectDiseasesen
dc.subjectMicrobiologyen
dc.subjectNutritionen
dc.subjectDiet therapyen
dc.subject.anzsrc321001 Clinical nutritionen
dc.titleHost-microbiota interactions underlying functional gastrointestinal disorders and the impact of gold kiwifruit consumption : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Albany, Manawatū, Palmerston North, New Zealanden
thesis.degree.disciplineNutritional Science
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.description.doctoral-citation-abridgedMiss Carco characterised the microbial-immune interactions in functional gastrointestinal disorders, and the microbiota responses to daily consumption of two gold kiwifruit in constipated subjects. The knowledge generated emphasised the interactions underlying the pathophysiology of functional gastrointestinal disorders, which can be used for future development of food-based treatments supporting gastrointestinal health and comfort.
thesis.description.doctoral-citation-longGrowing evidence supports the role of microbial-immune interactions in functional gastrointestinal disorders; however, these mechanisms are poorly understood. Miss Carco characterised the faecal microbiota and the immune cell transcriptome of subjects with functional gastrointestinal disorders and integrated these datasets with gastrointestinal- and non-gastrointestinal symptoms. She also investigated the microbiota responses to daily consumption of two gold kiwifruit in constipated subjects. The knowledge generated highlighted the value of using a systems biology approach to gain mechanistic insights into the microbiota-immune-mediated pathways underlying functional gastrointestinal disorders. This could lay the groundwork for future development of food-based treatments supporting gastrointestinal health and comfort.
thesis.description.name-pronounciationCA TE RI NA CAR COH
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