CXCL8 and rheumatoid arthritis: Various studies have reported the anti-inflammatory effect of iguratimod, which significantly suppresses IL-6, IL-8, granulocyte colony-stimulating factor (G-CSF), and granulocyte–macrophage colony-stimulating factor (GM-CSF) in RA synovial fibroblasts;21 TNF-α, IL-6, IL-8, MCP-1, and IL-1β from human monocyte THP-1 cells;26 and TNF-α from rat alveolar and mouse peritoneal macrophages.28