Interleukin-17A (IL-17A): Molecular Characteristics and Its Physiological and Pathological Significance—From Molecular Structure to Clinical Application

Interleukin-17A (IL-17A) is a proinflammatory cytokine that plays a crucial role in immune responses and tissue homeostasis. The expression of IL-17A is strictly regulated by transcription factors including RORγt and is mainly produced by Th17 cells, γδT cells, and innate lymphoid cells. IL-17A signals through a heterodimeric receptor complex consisting of IL-17RA and IL-17RC, leading to the activation of NF-κB and MAPK pathways. Recent studies have highlighted its functions in the central nervous system, with reported associations with multiple sclerosis and autism spectrum disorder. Furthermore, the development of IL-17A inhibitors has progressed significantly, showing high therapeutic efficacy particularly in autoimmune diseases. This review provides an overview of current knowledge regarding IL-17A, from its molecular characteristics to clinical applications.