β-Glucans from Saccharomyces cerevisiae as antiadhesive and immunomodulating polysaccharides against Campylobacter jejuni

Campylobacter jejuni is responsible for the majority of food-borne enteritis worldwide with severe cases of diarrhea and being the third leading cause of death globally. The bacterium strongly colonizes the intestine of poultry without affecting the animals, but leading to severe infections in humans after oral intake of contaminated eggs or undercooked meat. A commercially available β-1,3/1,6-glucan from Saccharomyces cerevisiae (BGL) was shown to interact with early host-pathogen interactions of C. jejuni to eucaryotic host cells. BGL with a β-1,3-D-glucose backbone and short oligosaccharide glucose side chains (DP4 to 6) at position O-6 of the backbone reduced C. jejuni adhesion to human intestinal Caco-2 cells in a concentration dependent manner (1-1000 μg/mL) up to 45 % within coincubation protocol. Preincubation of either bacteria or host cells with BGL indicated that C. jejuni is significantly impaired in its capability to recognize and to attach to eukaryotic host cells. In contrast, adhesion of untreated C. jejuni to BGL-pretreated host cells remains unchanged. Cellular viability of host cells and proliferation of the bacteria are not significantly influenced by BGL. Beside reduced adhesion to Caco-2 cells, BGL treatment of RAW 264.7 macrophages significantly stimulated phagocytosis of fluorescent-labeled zymosan particles as well as internalization of C. jejuni. Interestingly, BGL reduced also the bacterial adhesion to the macrophages, but phagocytosis of the bacteria is strongly stimulated. The observed effects of yeast glucans could prove beneficial for protecting intestinal cells from C. jejuni infection by inhibition of bacterial adhesion and by increased and faster elimination.