CX3CL1 and rheumatoid arthritis: Accordingly, FKN is considered to represent a therapeutic target in chronic inflammatory disorders (45); however, increasing evidence suggests that FKN (CX3CL1) is more correlated with immune-related inflammatory diseases including experimental autoimmune encephalomyelitis (46) and rheumatoid arthritis (47), and is also expressed in macrophages, fibroblasts, endothelial, and dendritic cells (45).