CXCL8 and rheumatoid arthritis: Specifically, among the cytokines closely associated with RA pathogenesis (IL‐6, IL‐8, IL‐1β, and TNF‐α),[33] the IL‐6 expression levels in the FME‐2 and FME‐1 cocultures were higher than those in the FM coculture (p < 0.05) (Figure 3B).