Identifying dietary additive regulated mechanisms impacting intestinal epithelial cell responses and inflammatory processes

In recent years, research has increasingly identified diet as a crucial factor in the development and management of gastrointestinal diseases like Inflammatory Bowel Disease (IBD). Dietary influences are now considered significant in determining an individual's susceptibility to IBD, yet much remains unknown about the long-term effects of various dietary components. The main objective of my thesis is to explore the mechanisms through which dietary emulsifiers and sweeteners influence gut epithelial cell health, with a focus on their potential role in exacerbating gastrointestinal diseases. The first part of the study focuses on the effects of food emulsifiers, specifically lecithin, carboxyethyl cellulose (CMC), and polysorbate 80 (p80), on human intestinal epithelial cells and murine organoids. While lecithin and CMC showed no significant harmful effects, p80 was found to induce cell death at concentrations below the FDA-approved level. Through RNA sequencing and a series of assays including cell viability, cell death, lipid peroxidation autophagy, Seahorse, transmission electron microscopy, western blotting to name a few, the study reveals that p80 triggers ferroptosis—a type of cell death associated with iron-dependent lipid peroxidation—causing mitochondrial damage. Interestingly, p80 did not seem to activate the inflammatory response in the cells. The second part of the thesis explores the role of the lipid peroxidation and lipid accumulation prompted by p80 and ferroptosis. Using lipidomic analysis and inhibitors targeting lipid formation enzymes, the research identifies specific lipid changes and profiles, especially in the polyunsaturated fatty acids, associated with ferroptosis. The study highlights how lipid metabolism is intricately linked to cell death mechanisms, suggesting potential therapeutic approaches to mitigate emulsifier-induced lipotoxicity by using lipid and ferroptosis inhibitors. In the final part, the study examines the effects of rare sugars and sweeteners on human intestinal epithelial cells under both steady-state and inflammatory conditions such as IBD. Among the sweeteners tested—Psicose, Lactitol, Maltitol, Saccharin, and Tagatose—saccharin shows a significant impact on gene expression, particularly under inflammatory conditions. Saccharin activates JAK/STAT pathway related to inflammation by increasing cytokine secretion and cell death, indicating a potential role of saccharin in potentiating intestinal inflammation. Collectively, this thesis provides comprehensive insights into how specific dietary additives influence intestinal cell health. By unravelling the complex interactions between diet and cellular processes, the study contributes to a better understanding of potential dietary risks and offers guidance for future research aimed at improving dietary management in IBD and GI-related disorders.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2024

Author dc:creator

• Saiz-Gonzalo, Gonzalo

Advisors dc:contributor.advisor

• Melgar Villeda, Silvia
• Joyce, Susan

• IBD, polysorbate 80
• Food additives
• Emulsifiers
• Cell death
• Inflammation
• Sweeteners
• Ferroptosis

Statement dc:rights

• © 2024, Gonzalo Saiz-Gonzalo.

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/16441

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/16441