The activation of the TLR-4-induced nuclear factor kappa-B (NF-κB) signalling pathway mediates the pro-inflammatory activity of M1 macrophages via TNF-α, IL-1β and IL-6 production and release in monocyte-derived (MDMs) and synovial macrophages in patients with RA [46]. Here, IL6 is linked to rheumatoid arthritis.