IL6 and rheumatoid arthritis: The sesquiterpene lactone-enriched fraction from Xanthium mongolicum Kitag exhibited the strongest anti-RA activity, which dose-dependently (from 1 to 640 μg/mL) decreased the expression of M1-related genes IL-6, -1β, TNF-α, -12b, and iNOS through the suppression of NF-kB signaling [160].