OP0182 PROTEOGLYCAN LOSS IN ARTICULAR CARTILAGE IS ASSOCIATED WITH JOINT INFLAMMATION SEVERITY IN PSORIATIC ARTHRITIS – A COMPOSITIONAL MAGNETIC RESONANCE IMAGING STUDY
Authors: P. Sewerin, D. Abrar, S. Nebelung, M. Frenken, T. Ulrich, K. L. Radke, G. Antoch, S. Vordenbäumen, R. Brinks, M. Schneider, B. Ostendorf, C. Schleich
Journal: Annals of the Rheumatic Diseases (2020)

Background: Even though cartilage loss is a known feature of psoriatic arthritis (PsA), little is known about its role in the pathogenesis of PsA. Using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) as a non-invasive marker of the tissue’s proteoglycan content, such early (i.e. pre-morphological) changes have been associated with inflammation in rheumatoid arthritis (RA). Yet, this association has not been studied before in PsA. Objectives: Is the severity of local joint inflammation associated to local proteoglycan loss in PsA patients? Methods: Metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints of 17 patients with active PsA were evaluated by high-resolution clinical standard morphological and dGEMRIC sequences using a 3T MRI scanner (Magnetom Skyra, Siemens) and a dedicated 16-channel hand coil. Images were analyzed by two independent raters for dGEMRIC indices, PsA MRI scores (PsAMRIS) and total cartilage thickness (TCT). Kendall-Tau correlation coefficients (τ) were calculated. Results: We found significant negative correlations between dGEMRIC indices and total PsAMRIS (τ = -0.5, p= 0.012), synovitis (τ = -0.56, p= 0.006), flexor tenosynovitis (τ = -0.4, p= 0.049), and periarticular inflammation (τ = -0.72, p&lt; 0.001). Significant positive correlations were found between TCT and dGEMRIC indices in all joint levels (τ = 0.43, p&lt;0.001). No significant correlations were determined between dGEMRIC indices and bone erosion, bone edema or bone proliferation. Conclusion: In PsA, proteoglycan loss as assessed by dGEMRIC is associated with periarticular inflammation, synovitis, and flexor tenosynovitis, but not with bone erosion or proliferation, thereby highlighting the need for effective anti-inflammatory treatment regimes. Beyond morphology, advanced MRI techniques may be used to assess cartilage composition in PsA and to identify early changes in cartilage as an imaging biomarker with potential application in detection and monitoring of PsA. Figure 1 Right hand of a 26-year-old male with psoriatic arthritis Coronal STIR image (A) of digits 1-5, transversal fat-saturated (fs) T2-weighted image of digits 2-4 (B) and the corresponding transversal fs contrast-enhanced T1-weighted image (C) at the distal portion of the proximal phalanges. Horizontal white bar in (A) indicates level of transversal slices (B) &amp; (C). Sagittal fs Proton Density-weighted image of the third digit (D). A: Increased signal at the collateral ligaments and synovitis of the proximal interphalangeal (PIP) joint of the third digit (white arrow). Periarticular inflammation around the PIP joint and the body of the proximal phalanx of the third digit (arrowhead). B &amp; C: Extensive flexor tenosynovitis (asterix) and periarticular inflammation in the subcutaneous tissues (arrowhead) alongside thickened flexor tendon pulleys (arrow). D &amp; E: Representative sagittal T1-weighted images of the MCP, PIP and DIP joint of the 3rd digit. Following iv contrast administration and appropriate delay of 40 min, A gives the morphological T1 map, while B gives the corresponding parameter map with dGEMRIC values [ms] overlaid. Note the significant decrease in dGEMRIC indices of the PIP joint as compared to the MCP joint. Disclosure of Interests: Philipp Sewerin Grant/research support from: AbbVie Deutschland GmbH &amp; Co. KG Bristol-Myers Squibb Celgene GmbH Lilly Deutschland GmbH Novartis Pharma GmbH Pfizer Deutschland GmbH Rheumazentrum Rhein-Ruhr, Consultant of: AMGEN GmbH AbbVie Deutschland GmbH &amp; Co. KG Biogen GmbHBristol-Myers Squibb Celgene GmbH Chugai Pharma arketing Ltd. / Chugai Europe GmbHHexal Pharma Janssen-CilagGmbH Johnson &amp; Johnson Deutschland GmbHLilly Deutschland GmbH / Lilly Europe / Lilly Global Novartis Pharma GmbH Pfizer Deutschland GmbH Roche Pharma Rheumazentrum Rhein-Ruhr Sanofi-Genzyme Deutschland GmbH Swedish Orphan Biovitrum GmbH UCB Pharma GmbH, Speakers bureau: AMGEN GmbH AbbVie Deutschland GmbH &amp; Co. KG Biogen GmbHBristol-Myers Squibb Celgene GmbH Chugai Pharma arketing Ltd. / Chugai Europe GmbHHexal Pharma Janssen-CilagGmbH Johnson &amp; Johnson Deutschland GmbHLilly Deutschland GmbH / Lilly Europe / Lilly Global Novartis Pharma GmbH Pfizer Deutschland GmbH Roche Pharma Rheumazentrum Rhein-Ruhr Sanofi-Genzyme Deutschland GmbH Swedish Orphan Biovitrum GmbH UCB Pharma GmbH, Daniel Abrar: None declared, Sven Nebelung: None declared, Miriam Frenken: None declared, Tim Ulrich: None declared, Karl Ludger Radke: None declared, Gerald Antoch: None declared, Stefan Vordenbäumen: None declared, Ralph Brinks: None declared, Matthias Schneider Grant/research support from: GSK, UCB, Abbvie, Consultant of: Abbvie, Alexion, Astra Zeneca, BMS, Boehringer Ingelheim, Gilead, Lilly, Sanofi, UCB, Speakers bureau: Abbvie, Astra Zeneca, BMS, Chugai, GSK, Lilly, Pfizer, Sanofi, Benedikt Ostendorf: None declared, Christoph Schleich: None declared