Role of IL-23 and Th17 Cells in Airway Inflammation in Asthma

Asthma is characterized by chronic airway inflammation with intense eosinophil and lymphocyte infiltration, mucus hyperproduction, and airway hyperresponsiveness. Accumulating evidence indicates that antigen-specific Th2 cells and their cytokines such as IL-4, IL-5, and IL-13 orchestrate these pathognomonic features of asthma. In addition, we and others have recently shown that IL-17-producing CD4(+) T cells (Th17 cells) and IL-23, an IL-12-related cytokine that is essential for survival and functional maturation of Th17 cells, are involved in antigen-induced airway inflammation. In this review, our current understanding of the roles of IL-23 and Th17 cells in the pathogenesis of allergic airway inflammation will be summarized.