IL6 and rheumatoid arthritis: Serum taken from synovial fluid of RA patients demonstrated high expression of IL-6 (Madhok et al., 1993), and it is generally thought that IL-6 can promote joint damage and inflammation by acting on vascular endothelial growth factor (VEGF), an angiogenic mediator that promotes increases in vasculature and permeability (Nakahara et al., 2003).