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Table 1 Biomarkers of bone, cartilage and synovial turnover, and the BIPED classification

From: Developments in the scientific understanding of osteoarthritis

Tissue Molecule Markers of synthesis Markers of degradation BIPED classification
Bone Type I collagen   PYDa B
    NTX-Ia,b D
    CTX-Ia,b P
  Noncollagenous proteins Osteocalcinb   P
Cartilage Type II collagen PIIANPb   P
   Total PIINP   D
   PIICPb,c   D, P
    CTX-IIa,c D, B, P, E
    Coll 2-1a,b P
    Coll 2-1 NO2a,b P
    C2Ca,b P, E
    1,2Ca,b P, E
  Aggrecan Epitope 846 (cartilage contentc)   E
  Nonaggrecan and noncollagenous proteins   COMPb,c D, B, P
    Pentosidinea,b P
  Proteases and their inhibitors   MMPsb B, P, E
    TIMPsb B, P
Synovium Type III collagen   GIc-GaI-PYDa E
  Noncolagenous proteins YKL-40b,c   B, E
   Hayluronic acidb   B, P
  1. aUrine. bSerum. c Synovial fluid. BIPED, B (burden of disease), I (investigative), P (prognostic), E (efficacy of intervention), D (diagnostic); C1,2C, assay that detects COL2-3/4C (short) epitope; C2C, assay that detects COL2-3/4C (long) epitope; Coll 2-1, 9-amino-acid peptide of type II collagen; Coll 2-1 NO2, nitrated form of Coll 2-1; COMP, cartilage oligomeric protein; CTX-I, carboxyl-terminal cross-linked telopeptide of type I collagen; CTX-II, C-terminal cross-linked telopeptide of type II collagen; Glc-Gal-PYD, glucosyl-galactosyl-pyridinoline; HELIX-II, helical type II collagen; MMP, matrix metalloproteinase; NTX-I, N-terminal cross-linked telopeptide of type I collagen; PIIANP, N-propeptide IIA of collagen type II; PIICP, C-propeptide of collagen type II; PIINP, N-propeptide II of collagen type II; PYD, pyridinoline; TIMP, tissue inhibitor of matrix metalloproteinase; YKL-40, cartilage glycoprotein 39. Reproduced with permission from Rouseeau and Delmas [80].