Following activation by pathogenic factors, these immune cells secrete a variety of pro-inflammatory cytokines, including TNF-α, IL-1, IL-6, IL-8, etc. In addition to immune cells, inflammatory cytokines can be released by FLSs under RA conditions, which play a key role in disease persistence and progression of RA [24–26]. This evidence concerns the gene IL6 and rheumatoid arthritis.