GDF15 and osteoarthritis: These may reflect differences in relevant biological pathways such as inflammation (e.g., IL6, CXCL6), body weight regulation/energy homoeostasis (e.g., LEP, GDF15), but also in proteins directly relevant to osteoarthritis, such as the proteoglycan ACAN (aggrecan)47 and AMBP (bikunin precursor)48.