Cutting-edge issues in autoimmunity and allergy of the digestive system.

Autoimmunity and allergy involving the digestive system may be considered as paradigmatic for numerous common themes of complex diseases secondary to tolerance breakdown. Among gastrointestinal autoimmune diseases, for example, we encounter diseases in which a clear environmental trigger is identified (i.e., celiac disease), serum autoantibodies are most specific (i.e., primary biliary cirrhosis), or in which the disease pathophysiology is clearly understood (i.e., autoimmune gastritis). Similarly, it is intriguing that the gastrointestinal tract and the liver circulation represent the crucial environment for the development of immune tolerance. This issue is dedicated to the discussion of recent concepts while identifying two major common issues, i.e., the need for serum biomarkers and the role of vitamin D. Other common themes characterize the etiology and effector mechanisms of these and other autoimmune diseases and are discussed in each cutting-edge overview.