CXCL8 and rheumatoid arthritis: A large number of studies have confirmed that cytokines are directly related to RA (Abdollahzad et al., 2015), such as TNF-α, IL-1β, IL-6, IL-8, IL-12, etc. In RA, TNF-α activates synovial fibroblasts, promotes epidermal proliferation, and recruits inflammatory cells.