Reference Number: 164
Intolerance & Sensitivity: Allergies
Despite its direct exposure to huge amounts of microorganisms and foreign and dietary antigens, the gut mucosa maintains intestinal homeostasis by utilizing the mucosal immune system. The gut mucosal immune system protects the host from the invasion of infectious pathogens and eliminates harmful non-self antigens, but it allows the cohabitation of commensal bacteria in the gut and the entry of dietary non-self antigens into the body via the mucosal surface. These physiological and immunological activities are regulated by the ingenious gut mucosal immune network, comprising such features as gut-associated lymphoid tissue, mucosal immune cells, cytokines, chemokines, antimicrobial peptides, secretory IgA, and commensal bacteria. The gut mucosal immune network keeps a fine tuned balance between active immunity (against pathogens and harmful non-self antigens) and immune tolerance (to commensal microbiota and dietary antigens), thus maintaining intestinal healthy homeostasis. Disruption of gut homeostasis results in persistent or severe gastrointestinal infection, inflammatory bowel disease, or allergic inflammation. In this review, we comprehensively introduce current knowledge of the gut mucosal immune system, focusing on its interaction with allergic inflammation.
The gut mucosal immune system maintains homeostasis through an ingenious network including such factors as GALT, immune cells of innate and acquired types, chemokines, and cytokines. External environmental factors such as commensal bacteria, vitamin A and metabolites participate in the construction of this unique gut mucosal homeostatic network. Disruption or deficiency of the components of the gut mucosal immune and homeostatic network lead to the impairment of oral tolerance, SIgA production, and mucosal barrier formation, eventually promoting allergen sensitization and allergic inflammation. Elucidation of the mechanisms creating and disrupting the intestinal mucosal immune and homeostatic network is key to the development of preventive and therapeutic approaches to allergy. Further studies exploring these mechanisms are critical.
Significance of the study to the baker
The gut mucosal immune system needs to act as a defence system against pathogens, while at the same time balancing this function with immune tolerance to dietary antigens and commensal bacteria. Evidence from studies is now being used to develop preventative and therapeutic approaches (including nutritional approaches) to allergies. This includes investigating the use of probiotics or prebiotics (or both) to help reduce the incidence of allergic disease in children.