Building Tolerance to Gut Bacteria: Quantification of Goblet Cell – Immune Interactions in the Proximal and Distal Colon

Abstract: Goblet cell - immune cell interactions and their role in inflammatory bowel disease Goblet cells, specialized mucus secreting cells lining the gut, are key players in mediating immune responses. While the mucus layer functions as a barrier against the intrusion of foreign bacteria into the host, substances from e.g food and bacteria are sampled and delivered to the immune system through the formation of goblet cell associated passages (GAPs). This process promotes the activation and maintenance of tolerance against dietary substances and our own flora and is crucial in the maintenance of gut balance and health. The disruption of goblet cell function leads to chronic inflammation seen in e.g. Crohn's disease, inflammatory bowel disease (IBD) and ulcerative colitis, which as of now have no cure. To get a deeper understanding of the role goblet cells have in tolerance and disease and how their interactions are regulated, a study was conducted to investigate the quantity of interactions between goblet cells and immune cells in different parts of the colon. Future studies will build upon this to discover what specific types of immune cell populations are interacting with goblet cells, and how these interactions affect them and their protein expression. To do this, tissue was extracted from mice to be stained with fluorescent antibodies that bind specific receptors on immune cells to visualize them using fluorescent microscopy. The mice had been genetically manipulated to express a red fluorescent protein in the mucus of goblet cells (Fig. 1). The number of interactions (see yellow arrow in Fig. 1) were quantified and different sections; start (proximal) and end (distal) of the colon were compared. The results showed, contrary to my hypothesis, that the number of interactions in the crypts was significantly higher in the proximal colon (mean: 50.2% of goblet cells) compared to the distal colon (mean: 40.9%). I expected bacterial inhibition of GAP formation in the proximal colon, where the mucus layer is thinner, enabling bacteria to be in closer proximity to the epithelium, to also inhibit goblet cell interaction with immune cells. Studies using antibiotics and other treatments to disrupt gut flora and the mucus layer could be conducted to investigate whether the observed differences in goblet cell interactions are due to differential exposure to bacteria. Supervisor: Jenny Gustafsson Bachelor’s degree project 15 credits in MOBK01, 2021 Institution of Physiology, Gothenburg University