IL17A and rheumatoid arthritis: As a new cytokine, IL-17A is the first identified member belonging to the IL-17 family (IL-17A-F) [11], which could induce the secretion of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, to exacerbate inflammatory responses [12], thus participating in numerous inflammatory-related diseases, including multiple sclerosis (MS) [13], cerebral ischemia [14], and rheumatoid arthritis (RA) [15].