CXCL8 and rheumatoid arthritis: In particular, IL-6, TNF-α, IL-1β, and IL-8 play a key role in the pathogenesis and development of arthritis, and high levels of these cytokines have been detected in both the serum and the SF of RA, gout, and CPPD patients [3,5,30,31,32,33,34].