OP0067 Dickkopf-1 (DKK1) serum levels and bone quality (tbs evaluation) in patients with systemic sclerosis and rheumatoid arthritis

Background Systemic sclerosis (SSc) as well as rheumatoid artrhritis (RA) patients present an increased risk of osteoporosis (OP) as a result of the chronic inflammatory state, low vitamin D, immobilisation and other causes. The Wnt/β-catenin pathway is signalling identified like a key promoters of the osteoblastogenesis hence of the new bone formation in inflammatory conditions. Dickkopf-1 (DKK1) is a natural inhibitor of Wnt signalling pathway that could be involved in promoting osteoclastogenesis through suppression of osteoprotegerin.1Trabecular Bone Score (TBS) is an index of bone quality extracted from dual-energy X-ray absorptiometry (DXA) analysis.2 Objectives In this study, bone mineral density (BMD) and Dkk-1 levels were evaluated in SSc patients, in order to investigate possible associations between systemic OP and/or osteopenia and Dkk-1 concentrations, according to their different nailfold videocapillaroscopic (NVC) patterns of microangiopathy (NVC patterns ‘Early’, ‘Active’, and ‘Late’)3 in SSc patients and to compare the results regarding bone quality with RA patients and healthy subjects (CNT). Methods Eighty-four SSc patients,98 rheumatoid arthritis (RA) and 60 CNT were studied. Dkk-1 serum levels were measured by ELISA methods (Quantikine Human DKK-1 Immunoassay R and D System, Minneapolis, USA). Bone Mineral Density (BMD, g/cm2) of the lumbar spine (L1-L4) was analysed by dual-energy X-ray absorptiometry (DXA) scan. Lumbar spine bone quality was derived from each spine DXA examination using the TBS analysis. Nailfold videocapillaroscopic (NVC) patterns were analysed as previous reported.3 25 hydroxyvitamin D (25(OH)D ng/ml) serum concentration was evaluated in all subjects. Results Serum DKK-1 levels were significantly higher in patients with SSc than in CNT (2892±1121 pg/ml vs 2044±692 pg/ml, p Conclusions The data obtained showed a significantly Increased of Dkk-1 serum concentrations together and a decreased bone mass (lower TBS and BMD) in SSc patients compared to CNT. The bone quality seems lower in SSc patients with more altered microvasculature (‘Late’ NVC pattern). References [1] Krishnan V, et al. J Clin Invest2006;116:1202–9. [2] Roux JP, et al. Osteoporosis Int2013;24:2455–60. [3] Cutolo M, et al. J Rheumatol2000;27:155–60. Disclosure of Interest None declared