Serum YKL-40 in psoriasis with and without arthritis; correlation with disease activity and high-resolution power Doppler ultrasonographic joint findings.

Abstract

YKL-40 may be involved in angiogenesis in psoriasis and psoriatic arthritis (PsA). High-resolution power Doppler ultrasound (PDUS) can detect angiogenesis of synovium in PsA. To assess serum YKL-40 in psoriasis patients with or without PsA, and to correlate its levels with disease activity and high-resolution PDUS findings. In this case-control study, 48 patients with psoriasis (26 of them also had PsA) and 30 controls were assessed by high-resolution PDUS, and assayed for serum levels of YKL-40 by ELISA. Patients were clinically assessed using Composite Psoriatic Disease Activity Index (CPDAI). Total joint score (TJS) was used to assess joint involvement in PsA. A statistically significant elevation was found in YKL-40 levels in psoriatics with or without PsA compared with controls (P<0.001), as well as in PsA (group II) compared to patients without arthritis (group I) (P=0.002). CPDAI, synovial thickness score and colour Doppler ultrasound (CDUS) score were highly significantly higher in group II vs. group I (P<0.001). In all patients, CPDAI, synovial thickness and CDUS score were positively correlated to each other, and each of them was positively correlated to serum YKL-40 levels (P<0.05). In either group I or II, serum YKL-40 levels correlated positively with CPDAI (P<0.05). In group II, TJS, synovial thickness and CDUS score were positively correlated to each other (P<0.05). Serum YKL-40 can be used as a new biological marker for angiogenesis and disease activity in psoriasis with or without PsA. High-resolution PDUS is a non-invasive tool for the evaluation of angiogenesis in PsA patients as well as for the detection of early synovial changes in psoriasis patients without arthritis.