Enhancing vaccination efficacy by application of in vitro preselected dietary fibers and lactic acid bacteria

Much attention has been given by the scientific community to dietary fibers and lactic acid bacteria to modulate immunity and enhance well-being of consumers. Up to now, the positive effects were mainly attributed to the effects of bacteria in the gut that promote health. These effects are considered to be indirect as they rely on the molecules produced by the bacteria that live in the gut, the microbiota. However, direct effects of food components on immune cells and well-being were also recently reported. This thesis aimed at further understanding the mechanisms behind the direct immune activities of dietary fibers and lactic acid bacteria (LAB) which are all commonly consumed. Using a screening platform with cells that mimick the gut allowed to measure effects on different health parameter. The gut’s barrier integrity was strongly enhanced by a specific LAB. The combination of a LAB with a dietary fiber had synergistic effects on immune cell receptors. Furthermore, this combination was proved to enhance oral vaccination efficacy in neonatal piglets despite the immaturity of their immune system. The enhancement of vaccination could not be solely explained by microbiota changes, suggesting that direct immune effects are at play. Our studies will contribute to the selection of effective food components that can stimulate the immunity of the consumers