Nutritional strategies for mucosal health: the interplay between microbes and mucin glycans

Many aspects of the mechanisms underlying the symbiosis between humans and gut microbes remain unknown and encompass some of the most intriguing questions in microbiome research. An important factor in this symbiosis is the interplay between microbes and human-produced glycans in mucin and breast milk. In this Opinion paper, I propose a synergy between the structural diversity of human mucin glycans and the enzymatic repertoire of the gut microbiome. The contribution of microbes to mucosal health is discussed, and the role of breast milk glycans in mucosal colonization by microbes is explained. The use of prebiotic mucin glycans in general, and specialized infant and medical nutrition in particular, should be considered as the field of interest to modulate the microbiota and improve mucosal health. The gut mucosa forms a protective barrier for epithelial cells but also serves as an ecological niche for specific nonharmful members of the microbiota.The degradation of mucin glycans by the microbiome leads to a pool of microbial products that are beneficial for host mucus production and for immune and metabolic responses.Mucin glycans are catabolized by microbes through a sequential action of different microbial enzymes, and cross-feeding between microbes is taking place while scavenging the mucin glycan structures leading to a microbial ecological network.Human milk and mucin glycans show similar molecular characteristics and sugar code.A proper seeding of the gut mucosa with microbes in early life will positively stimulate host immune and metabolic health in later life.The use of food containing synthetic glycans designed to target microbial activity at the mucosa will enhance colonization with beneficial microbes, and their presence and glycan-degrading activity will stimulate mucosal health.