Differentiating patients with psoriasis from psoriatic arthritis using collagen biomarkers

Objective Around 30% of patients diagnosed with cutaneous psoriasis (PsC) will go on to develop psoriatic arthritis (PsA) which includes inflammation of the joints. Collagens are core proteins in all tissues, which are involved in the inflammatory process in both PsC and PsA. The aim of this study is to investigate collagen biomarkers and their potential use in separating the three patient groupings: PsC, PsA and healthy donors. Methods Healthy donors (n=41), patients with PsC (n=30) and patients with PsA (n=30) were recruited. Clinical disease parameters were recorded. Collagen remodelling was measured using ELISA immunoassays which detect the serological anabolic biomarkers quantifying formation of type I, III and IV collagen (PRO-C1, PRO-C3 and PRO-C4 respectively), and the catabolic biomarkers measuring degradation of type I, II, III, IV and X collagen (C1M, C2M, C3M, C4M and C10C respectively). Results Patients with PsC and PsA presented lower levels of PRO-C1 and C3M compared to healthy controls (p<0.05-p<0.0001), C1M was higher in PsA compared to healthy controls (p<0.0001) and C2M was all elevated in PsC and PsA compared to healthy controls (p=0.0002 and p=0.0004 respectively), reflecting alterations in the tissues. In addition, C1M was able to separate between PsC and PsA patients with an AUROC=0.664, indicating that this biomarker may be a biomarker of joint involvement. Conclusion This work provides evidence that serum collagen biomarkers are dysregulated in PsC and PsA, as compared to healthy controls. C1M was able to differentiate patients with PsC from PsA and could be a potential biomarker of inflammatory systemic musculoskeletal involvement.