Soluble biomarkers differentiate patients with psoriatic arthritis from those with psoriasis without arthritis

Objective. Biomarkers may be helpful in screening patients with psoriasis for PsA. Our purpose was to identify serum biomarkers for psoriasis and PsA. Methods. Fifty-two patients with psoriasis (26 satisfying CASPAR classification criteria for PsA) and 26 healthy controls were recruited for our study. Patients with psoriasis and PsA were group matched for age, sex and psoriasis duration, whereas controls were matched for age and sex. Blood samples were drawn at the time of assessment and serum was analysed for the following: IL-12, IL-12p40, IL-17, TNF super family member 14 (TNFSF14), MMP-3, RANK ligand (RANKL), osteoprotegerin (OPG), cartilage oligomeric matrix protein (COMP), C-propeptide of Type II collagen (CPII), collagen fragment neoepitopes Col2-3/4(long) (mono) (C2C) and Col2-3/4(short) (C1-2C) and highly sensitive CRP (hsCRP). Data were analysed using logistic regression and receiver operating characteristic curves were plotted. Results. Fifty-two patients with psoriatic disease had a mean age of 46 years and psoriasis duration of 16.8 years. Compared with controls, increased serum levels of RANKL, TNFSF14, MMP-3 and COMP independently associated with psoriatic disease (P<0.05). Twenty-six PsA patients (mean swollen and/or tender joint count 16, swollen joint count 5) were then compared with 26 patients who had psoriasis alone. Increased levels of hsCRP, OPG, MMP-3 and the CPII : C2C ratio were independently associated with PsA (P<0.03). Conclusion. This pilot study indicates that hsCRP, OPG, MMP-3 and the CPII : C2C ratio are biomarkers for PsA in patients with psoriasis.