Under the influence of joint disease, many cytokines and collagen turnover biomarkers accumulate in synovial fluid, including COMP, CC-chemokine ligand 5 (CCL5), matrix metalloproteinase-1 (MMP-1), MMP-3 and MMP-18, as well as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and IL-8 [121]. Here, IL6 is linked to arthropathy.