In RA, IL-17 activates pathogenic cells by inducing the production of proinflammatory cytokines, including IL-1β, IL-6, and TNF-α [5–7], and activated signal transducer and activator of transcription 3 (STAT3) was shown to be present in inflamed synovia in an animal model of RA [8]. Here, IL17A is linked to rheumatoid arthritis.