Chondrocyte activity is increased in psoriatic arthritis and axial spondyloarthritis.
Psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) are chronic inflammatory rheumatic diseases with complex origins. Both are characterized by altered extracellular matrix remodeling in joints and entheses that results in destructive and osteochondral proliferative lesions. There is a need for biomarkers reflecting core disease pathways for diagnosis and disease mapping. Pro-C2 reflects mature cartilage collagen type IIB formation, while C-Col10 represents turnover of type X collagen, which is exclusively expressed by hypertrophic chondrocytes. The objectives of this study were to study cartilage metabolism in axSpA and PsA by assessing Pro-C2 and C-Col10 and to evaluate their diagnostic utility against a healthy reference population.



Patients with PsA (n = 101) or axSpA (n = 110) were recruited consecutively from three rheumatology outpatient clinics. Demographic and clinical disease measures were recorded. Pro-C2 and C-Col10 were quantified in serum by using newly developed and specific competitive enzyme-linked immunosorbent assays based on monoclonal antibodies. One-way analysis of variance and Tukey's multiple comparison tests were performed on log-transformed data. ROC curve analysis was carried out to evaluate their discriminative power.



Pro-C2 levels in serum were significantly increased in both axSpA (median concentration 1.11 ng/ml, 0.67-1.64) and PsA (median concentration 1.03 ng/ml, 0.53-1.47) compared with healthy controls (median concentration 0.30 ng/ml, 0.16-0.41) (p < 0.0001). Pro-C2 did not differ according to treatment. C-Col10 was slightly but equally elevated in the PsA and axSpA groups vs. the control group, but it was significantly lower in patients with axSpA undergoing tumor necrosis factor-α inhibitor (TNFi) treatment. ROC curve analysis revealed AUCs of 0.85 (95 % CI 0.79-0.89) for axSpA and 0.81 (95 % CI 0.75-0.86) for PsA.



These findings indicate that cartilage collagen metabolism was enhanced in the axSpA and PsA groups compared with the healthy control group. The lower C-Col10 level in patients with axSpA undergoing TNFi treatment may reflect that hypertrophic chondrocytes in axSpA are targeted by TNFi. ROC curve analysis showed a diagnostic potential for Pro-C2 in axSpA and PsA.
Nordic Bioscience Biomarkers and Research, Herlev Hovedgade 207, Herlev, 2730, Denmark. nsg@nordicbioscience.com.
Natasja Stæhr
NS
Gudmann
Department of Rheumatology, Odense University Hospital, Odense, Denmark.
Heidi Lausten
HL
Munk
Department of Rheumatology, Vejle Hospital, Vejle, Denmark.
Anne Friesgaard
AF
Christensen
Department of Rheumatology, Esbjerg Hospital, Esbjerg, Denmark.
Leif
L
Ejstrup
Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.
Grith Lykke
GL
Sørensen
Department of Rheumatology, Vejle Hospital, Vejle, Denmark.|Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark.
Anne Gitte
AG
Loft
Nordic Bioscience Biomarkers and Research, Herlev Hovedgade 207, Herlev, 2730, Denmark.
Morten Asser
MA
Karsdal
Nordic Bioscience Biomarkers and Research, Herlev Hovedgade 207, Herlev, 2730, Denmark.
Anne-Christine
AC
Bay-Jensen
Nordic Bioscience Biomarkers and Research, Herlev Hovedgade 207, Herlev, 2730, Denmark.
Yi
Y
He
Nordic Bioscience Biomarkers and Research, Herlev Hovedgade 207, Herlev, 2730, Denmark.
Anne Sofie
AS
Siebuhr
Department of Rheumatology, Odense University Hospital, Odense, Denmark.
Peter
P
Junker
D000328:Adult; D019540:Area Under Curve; D015535:Arthritis, Psoriatic / Q000378:metabolism / Q000473:pathology*; D015415:Biomarkers / Q000097:blood; D002358:Cartilage, Articular / Q000378:metabolism / Q000473:pathology; D019902:Chondrocytes / Q000378:metabolism / Q000473:pathology*; D024043:Collagen Type II / Q000032:analysis / Q000097:blood*; D024121:Collagen Type X / Q000032:analysis / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D012372:ROC Curve; D012680:Sensitivity and Specificity; D025241:Spondylarthritis / Q000378:metabolism / Q000473:pathology*
D015415:Biomarkers; D024043:Collagen Type II; D024121:Collagen Type X
C-Col10; Pro-C2; Psoriatic arthritis; Spondyloarthritis; Type II collagen; Type X collagen