IL6 and rheumatoid arthritis: Inflammatory cytokines and chemokines produced by synovial fibroblasts play a crucial role in the progression of RA disease6; the principal inflammatory cytokines are IL-1β, IL-6 and TNF-α, while chemokines CCL2, IL-17β and Intercellular Adhesion Molecule 1 (ICAM-1) regulate leukocyte migration and infiltration, and upregulated expression of angiogenic factors in RA include most notably vascular endothelial growth factor (VEGF), as well as angiopoietins -1 and -2 (Ang-1 and Ang-2).