The role of IL-33 and mast cells in allergy and inflammation.

Interleukin-33 (IL-33) is a member of the interleukin-1 (IL-1) cytokine family. It is preferentially and constitutively expressed in different structural cells such as epithelial cells, endothelial cells, and smooth muscle cells. During necrosis of these cells (after tissue injury or cell damage), the IL-33 that is released may be recognized by different types of immune cells, such as eosinophils, basophils and, especially, mast cells. IL-33 needs the specific receptor ST2 (membrane-bound receptor) and Interleukin-1 receptor accessory protein heterodimer for its binding, which instigates the production of different types of cytokines and chemokines that have crucial roles in the exacerbation of allergic diseases and inflammation. IL-33 and mast cells have been influentially associated to the pathophysiology of allergic diseases and inflammation. IL-33 is a crucial regulator of mast cell functions and might be an attractive therapeutic target for the treatment of allergic and inflammatory diseases. In this review, we summarize the current knowledge regarding the roles of IL-33 and mast cells in the pathogenesis of allergies and inflammation.