Tailored Combinations of Human Milk Oligosaccharides Modulate the Immune Response in an In Vitro Model of Intestinal Inflammation

Infants rely on their developing immune system and the protective components of breast milk to defend against bacterial and viral pathogens, as well as immune disorders such as food allergies, prior to the introduction of solid foods. When breastfeeding is not feasible, fortified infant formula will most frequently be offered, usually based on a cow's milk-based substitute. The current study aimed to explore the immunomodulatory effects of combinations of commercially available human milk oligosaccharides (HMOs). An in vitro co-culture model of Caco-2 intestinal epithelial cells and THP-1 macrophages was established to replicate the hallmarks of intestinal inflammation and to evaluate the direct effects of different synthetic HMO combinations. Notably, a blend of the most prevalent fucosylated and sialylated HMOs, 2'-fucosyllactose (2'-FL) and 6'-siallylactose (6'-SL), respectively, resulted in decreased pro-inflammatory cytokine levels. These effects were dependent on the HMO concentration and on the HMO ratio resembling those in breastmilk. Interestingly, adding additional HMO structures did not enhance the anti-inflammatory effects. This research highlights the importance of carefully selecting HMO combinations in nutritional products, particularly for infant milk formulations, to effectively mimic the benefits associated with breastmilk.