Background/Purpose:

The events that underlie the transition from psoriasis (Ps) to psoriatic arthritis (PsA) are not well understood, although up to 30% of Ps patients develop PsA within 8 to 10 years. A biomarker for subclinical joint inflammation in Ps patients would provide a tool allowing earlier intervention. Ultrasound (US) findings of PsA have been reported in Ps patients without MSK symptoms, but the prevalence of these findings varies in different studies, many without healthy controls. One cellular marker, circulating osteoclast precursors (OCP), is significantly higher in Ps than healthy controls (HC). The purpose of study is to analyze and correlate serum, cellular and imaging biomarkers of arthritis in Ps patients and controls to facilitate early interventions and improve outcomes.

Methods: US studies and serologic assessment for OCP and OCP subsets were performed on Ps patients (dermatologist confirmed) and HC. All US studies were performed on a GE LOGIQ E9 unit, and read by a rheumatologist certified in MSK US (RT). A modification of the PsASon system was used including the four domains: I. Joint: gray scale (GS) synovitis, power Doppler (PD) signal, erosion and osteophytes; II. Tenosynovitis: GS and PD; III. Peritendinitis: GS and PD; IV. Enthesitis: tendon structure, thickness, enthesis associated bursitis, erosion, calcification or PD signal. US assessment included the bilateral radiocarpal and midcarpal joints, MCP joints, IP joints and PIP joints; 4^th and 6^th extensor compartments, flexor tendons 2-5 for tenosynovitis, extensor tendons 1-6 for peritendinitis; and bilateral elbow, knee, dorsal and plantar calcaneal entheses. Serum 14-3-3η levels were assayed by ELISA and blood samples were drawn for OCP quantification from purified monocytes after 8-day cell culture. The OCP were quantitated as #TRAP positive cells per 100,000 monocytes.

Results: 150 patients were screened at the University of Rochester and regional dermatology practices. 78 Ps patients (mean age 49.5; mean BMI 31.9; mean disease duration 20 years; f, n=42;m, n=36) and 25 HC (mean age 43; mean BMI 27.3; f, n=17;m, n=8) were enrolled. No subject had symptoms or physical findings of PsA. Complete OCP data were available for 74 Ps and 20 HC subjects. US assessments were obtained in all HC and 75 Ps subjects. The frequency of OCP in the healthy; PDUS- and PDUS+ groups was 649.4 +/- 947.5; 843.6 +/-1545 and 1514.2. Levels of 14-3-3η were not elevated in patients or controls.

Conclusion:

Imaging abnormalities were noted in almost 50% of Ps patients without MSK symptoms. This was significantly higher than in HC. Findings included synovitis, enthesitis and increased PD signals. The frequency of OCP was significantly higher in Ps patients than controls, and most elevated in patients with US findings. Serum levels of 14-3-3η were not increased in patients or controls. The combination of US findings and elevated OCP has potential to identify Ps patients at risk for developing PsA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/serum-cellular-and-imaging-markers-of-arthritis-in-psoriasis-patients-and-healthy-controls/