title: Type I and III collagen turnover is increased in axial spondyloarthritis and psoriatic arthritis. Associations with disease activity and diagnostic capacity.
abstract: OBJECTIVE
  To investigate the turnover of type I and III collagen by neo-epitope markers in patients with axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA).
  
  
  METHODS
  Patients with PsA (n=101) or axSpA (n=110) and healthy subjects (n=120) were included. Demographic and clinical data were recorded. Markers of type I and III collagen were quantified by RIA (ICTP) or ELISA (C1M and C3M). Non-parametric statistics were applied for intergroup comparisons and correlation studies. The diagnostic potential of these marker molecules was assessed by ROC analysis.
  
  
  RESULTS
  C1M and C3M, which originate from soft connective tissues, were significantly higher in axSpA and PsA as compared with healthy control subjects. CIM and C3M correlated with ASDAS and DAS28. Overall, ICTP, which arises from bone degradation, did not differ between disease versus healthy. However, ICTP was lower in HLA-B27 positive than in HLA-B27 negative patients with axSpA. There was no association between bone and soft connective tissue collagen I markers (ICTP and C1M), while C1M and C3M were highly correlated (p<0.0001). C1M discriminated between healthy and diseased with AUCs of 0.83 for PsA and 0.79 for axSpA. C3M AUCs were 0.77 for PsA and 0.78 for axSpA.
  
  
  CONCLUSIONS
  Type I and III collagen remodelling in soft connective tissue is increased in axSpA and PsA and associates with disease activity. Bone collagen degradation is lower in HLA-B27 positive compared with HLA-B27 negative axSpA, which may represent an aspect of enhanced enthesopathic bone proliferation in HLA-B27 carriers. C1M and C3M distinguish well between healthy and diseased individuals.
authors.affiliation: Nordic Bioscience, Biomarkers and Research, Herlev, Denmark. nsg@nordicbioscience.com.
authors.forename: Natasja Stæhr
authors.initials: NS
authors.lastname: Gudmann
authors.affiliation: Nordic Bioscience, Biomarkers and Research, Herlev, Denmark.
authors.forename: Anne Sofie
authors.initials: AS
authors.lastname: Siebuhr
authors.affiliation: Department of Rheumatology, Vejle Hospital, Denmark.
authors.forename: Anne Friesgaard
authors.initials: AF
authors.lastname: Christensen
authors.affiliation: Department of Rheumatology, Esbjerg Hospital, Denmark.
authors.forename: Leif
authors.initials: L
authors.lastname: Ejstrup
authors.affiliation: Institute of Molecular Medicine, University of Southern Denmark.
authors.forename: Grith Lykke
authors.initials: GL
authors.lastname: Sørensen
authors.affiliation: Department of Rheumatology, Vejle Hospital; and Department of Rheumatology, Aarhus University Hospital, Denmark.
authors.forename: Anne Gitte
authors.initials: AG
authors.lastname: Loft
authors.affiliation: Nordic Bioscience, Biomarkers and Research, Herlev, Denmark.
authors.forename: Morten Asser
authors.initials: MA
authors.lastname: Karsdal
authors.affiliation: Nordic Bioscience, Biomarkers and Research, Herlev, Denmark.
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Bay-Jensen
authors.affiliation: Department of Rheumatology, Odense University Hospital, Denmark.
authors.forename: Heidi Lausten
authors.initials: HL
authors.lastname: Munk
authors.affiliation: Department of Rheumatology, Odense University Hospital, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Junker
mesh_terms: D000328:Adult; D019540:Area Under Curve; D015535:Arthritis, Psoriatic / Q000235:genetics / Q000378:metabolism*; D016022:Case-Control Studies; D024042:Collagen Type I / Q000378:metabolism*; D024061:Collagen Type III / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015796:HLA-B27 Antigen / Q000235:genetics; D006801:Humans; D008297:Male; D010455:Peptides / Q000378:metabolism*; D012372:ROC Curve; D011863:Radioimmunoassay; D012720:Severity of Illness Index; D025242:Spondylarthropathies / Q000235:genetics / Q000378:metabolism
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D015796:HLA-B27 Antigen; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide