Is It Dietary Insulin?
Article first published online: 9 NOV 2006
Annals of the New York Academy of Sciences
Volume 1079, Immunology of Diabetes IV: Progress in Our Understanding pages 350–359, October 2006
How to Cite
VAARALA, O. (2006), Is It Dietary Insulin?. Annals of the New York Academy of Sciences, 1079: 350–359. doi: 10.1196/annals.1375.054
- Issue published online: 9 NOV 2006
- Article first published online: 9 NOV 2006
- gut immune system;
- β cell autoimmunity;
- enteral infections
Abstract: In humans the primary trigger of insulin-specific immunity is a modified self-antigen, that is, dietary bovine insulin, which breaks neonatal tolerance to self-insulin. The immune response induced by bovine insulin spreads to react with human insulin. This primary immune response induced in the gut immune system is regulated by the mechanisms of oral tolerance. Genetic factors and environmental factors, such as the gut microflora, breast milk-derived factors, and enteral infections, control the development of oral tolerance. The age of host modifies the immune response to oral antigens because the permeability of the gut decreases with age and mucosal immune response, such as IgA response, develops with age. The factors that control the function of the gut immune system may either be protective from autoimmunity by supporting tolerance, or they may induce autoimmunity by abating tolerance to dietary insulin. There is accumulating evidence that the intestinal immune system is aberrant in children with type 1 diabetes (T1D). Intestinal immune activation and increased gut permeability are associated with T1D. These aberrancies may be responsible for the impaired control of tolerance to dietary insulin. Later in life, factors that activate insulin-specific immune cells derived from the gut may switch the response toward cytotoxic immunity. Viruses, which infect β cells, may release autoantigens and potentiate their presentation by an infection-associated “danger signal.” This kind of secondary immunization may cause functional changes in the dietary insulin primed immune cells, and lead to the infiltration of insulin-reactive T cells to the pancreatic islets.