IL6 and rheumatoid arthritis: Nuclear factor kappa-Β (NF-κB) is closely related to RA progression, as it can promote the production of inflammatory cytokines such as interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in fibroblast-like synoviocytes (FLSs) and macrophages [4].