title: Serum YKL-40 levels in healthy children and adults. Comparison with serum and synovial fluid levels of YKL-40 in patients with osteoarthritis or trauma of the knee joint.
abstract: YKL-40 is a recently discovered human glycoprotein which is related in amino acid sequence to the chitinase protein family. YKL-40 is a major secretory protein of human chondrocytes and synoviocytes, and could play a role in tissue remodelling. The aim of the study was to establish the serum YKL-40 level in normal subjects and to evaluate serum YKL-40 as a marker for osteoarthritis. Serum YKL-40 was 80 micrograms/l in healthy children (n = 476) and 102 micrograms/l in healthy adults (n = 260). No age or sex differences were found in serum YKL-40 in subjects younger than 70 yr, but thereafter serum YKL-40 increased significantly. Patients with late-stage osteoarthritis of the knee (n = 37) had significantly higher serum YKL-40 (1.5-fold; P < 0.01) compared to healthy age-matched subjects, whereas patients with early-stage osteoarthritis of the knee or recent torn cruciate ligaments or menisci did not have elevated serum YKL-40. The level of YKL-40 in serum and synovial fluid correlated significantly, and 10-fold higher values were found in synovial fluid. YKL-40 levels in serum and synovial fluid of patients with acute severe synovial inflammation were significantly higher (P < 0.05-P < 0.001) than those in patients with no, light or moderate synovitis of the knee joint. Furthermore, YKL-40 correlated significantly (P < 0.01) with the amino-terminal propeptide of type III procollagen, but not with serum C-reactive protein. Our data indicate that YKL-40 in synovial fluid and serum may reflect human articular cartilage degradation and the degree of synovial inflammation in the knee joint.
authors.affiliation: Department of Medicine, University of Copenhagen, Hvidovre Hospital, Denmark.
authors.forename: J S
authors.initials: JS
authors.lastname: Johansen
authors.forename: J
authors.initials: J
authors.lastname: Hvolris
authors.forename: M
authors.initials: M
authors.lastname: Hansen
authors.forename: V
authors.initials: V
authors.lastname: Backer
authors.forename: I
authors.initials: I
authors.lastname: Lorenzen
authors.forename: P A
authors.initials: PA
authors.lastname: Price
mesh_terms: D054392:Adipokines; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D002648:Child; D000071451:Chitinase-3-Like Protein 1; D005260:Female; D006023:Glycoproteins; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis / Q000473:pathology*; D007719:Knee Joint / Q000737:chemistry*; D037102:Lectins; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000097:blood / Q000473:pathology*; D011506:Proteins / Q000032:analysis*; D011863:Radioimmunoassay; D012016:Reference Values; D013582:Synovial Fluid / Q000737:chemistry*; D013585:Synovitis / Q000473:pathology
chemical_list: D054392:Adipokines; D015415:Biomarkers; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins; D011506:Proteins