The intestinal glycome and its modulation by diet and nutrition

The human gastrointestinal epithelium is responsible for adequate digestion and absorption of nutrients. It is an immunological interface and highly selective environment that facilitates colonization by commensal bacteria and prohibits adhesion and invasion of pathogenic agents. The epithelial barrier is reinforced by the intestinal glycome, which consists of the vast array of sugar structures and glycoconjugates expressed by cells of the gastrointestinal tract. Aberrant glycosylation is associated with altered responses to enteric infections as well as immune dysregulation. Intestinal glycosylation is susceptible to alteration by genetic, physiological, and pathological states, in addition to modification by nutritional and environmental stimuli. The effects of nutritional influences upon glycan assembly and topology are of particular importance in intestinal barrier reinforcement and homeostasis. For instance, milk contains factors that can alter intestinal glycosylation, which in turn contributes to early immune development and maturation of the newborn intestinal tract. This review focuses on the glycosylation status of intestinal cells and the means by which nutritional factors modulate the expression and presentation of intestinal glycans.