Mom's sweet gift:The beneficial effects of human milk oligosaccharides and their structure-function relationships

Human milk oligosaccharide (hMO) is the third-largest solid compound and the most abundant bioactive molecule in human milk. The beneficial effects of hMOs in human milk are broadly acknowledged but the underlying mechanisms are still insufficiently understood. Especially the impact of individual hMOs on the intestinal immune system are still largely unknown. It is important to study now single instead of mixtures of hMOs are used in functional foods and infant formula. In this thesis, we tested different individual hMOs as well as a hMO’s acid hydrolysis product (after passing the stomach) on different cellular systems that represent essential parts of the gastrointestinal immune barrier. We showed that hMOs contribute to the reinforcement of the gastrointestinal immune barrier via direct and indirect modulatory effects, but all in a structure-dependent way. Slight differences in structure have a significant impact on the biological action of an hMO. Specific hMOs can influence growth and function of gut microorganisms. We also identified a new potential receptor for hMOs on gut epithelial cells and proved the importance of cross-talk and the presence of peristaltic movements on impact of hMOs. Our data contribute more knowledge about the structure-function relationship of hMOs, bring new insights for the future hMOs study, and helps for the future design of hMO containing products for the specific target groups