The mucosal barrier: Protective frontier to the outside world

The mucosal surfaces throughout the body are designed to provide an interface which can tolerate and protect at the same time. They need to screen the external environment and select for transport of required factors, such as nutrients from the diet, interact with the microflora present – taking benefit from those commensal strains while resisting pathogens, act as a milieu for an assortment of antimicrobial molecules and also combat attack from aggressive chemical and other microbiological agents. The system must be dynamic so that a continuous intact protective barrier is maintained at all times. Failure of the barrier leads to pathological conditions, and abnormal barrier components are among well known biomarkers for mucosal diseases. This brief review highlights some of the aspects relating to gut metabolism and mucosal protection.