TIMP1 and osteoarthritis: Genes procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2), collagen type I α1 chain (COL1A1), and tissue inhibitor of metalloproteinase 1 (TIMP1) are shown upregulating in osteoarthritis-related fibrosis; they are usually considered to be fibrotic markers [6].