SAT0585 Decreased synovial levels of dickkopf-1 are associated with radiological progression in knee osteoarthritis patients
Authors: W.A. Hassan, E.G. Behiry
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Dickkopf-1 (Dkk-1) is a direct inhibitory ligand of Wnt β-catenin signalling pathway that act through binding to low-density lipoprotein (LDL) related proteins (LRP5/6) receptors.Dkk-1 is considered an important mediator of cartilage homeostasis and skeletal remodelling.<sup>1</sup> <h3>Objectives</h3> This study aimed to measure serum and synovial fluid (SF) levels of Dkk-1 in patients with early primary knee osteoarthritis (KOA) and to examine the relationship between these levels and the clinical and functional parameters as well as radiological progression of KOA <h3>Methods</h3> We measured Dkk-1 in the serum (n=48) and SF samples (n=22) from 48 early KOA patients and in the serum from healthy control (n=30). Body mass index (BMI), numerical rating scale of pain (NRSP) and The Western Ontario Mc Master scale (WOMAC) were recorded. Plain radiographs using Osteoarthritis Research Society International (OARSI) atlas to assess joint space narrowing (JSN)<sup>2</sup> and musculoskeletal ultrasound examination (MSUS) were performed at baseline and after 24 months to assess radiological progression. Radiological progression was considered if there is more than 2 points increase in JSN score or transition to higher grade in MSUS examination<sup>3</sup> at the 24 months follow up period compared to baseline grade. <h3>Results</h3> SF Dkk-1 levels were significantly decreased (mean ±SD 115.05±34.2 pg/ml) compared to their paired serum levels (mean ±SD 969.82±365.72 pg/ml), p&lt;0.001 in KOA patients. There was no significant difference in serum Dkk-1 levels between KOA patients and healthy controls (mean ±SD 988.77±385.19 pg/ml and 1084.73±408.38 pg/ml respectively), the SF concentrations of Dkk-1significantly correlated with the baseline thickness of the cartilage on the medial condyle (0.53, p&lt;0.05) but not on the lateral condyle of the femur (r=0.11, p&gt;0.05).there was no significant correlation between serum Dkk-1and baseline cartilage thickness on medial and lateral condyles ((r= −0.13 and −0.09 respectively, p&lt;0.05). Patients in the least quartile of SF Dkk-1had an increased risk of radiological progression with plain radiography and MSUS (age, sex and BMI adjusted RR 2.1 and 3.4, 95% CI respectively. <h3>Conclusions</h3> Osteoarthritis patients have significantly lower synovial levels than serum levels of Dickkopf-1 that were obviously associated with radiological progression on plain radiography and MSUS suggesting that it could be a useful marker to reflect OA severity and implies a possible role in the pathogenesis of OA. <h3>References</h3> [1] Min S, Wang C, Lu W, Xu Z, Shi D,Chen D, et al. Serum levels of the bone turnover markers dickkopf-1, osteoprotegerin, and TNF-α in knee osteoarthritis patients. Clin Rheumatol2017Oct;36(10):2351–2358. [2] Altman RD, Hochberg M, Murphy WA, Jr, Wolfe F, Lequesne M. Atlas of individual radiographic features in osteoarthritis. Osteoarthritis Cartilage1995;3(Suppl A):3–70. [3] Saarakkala S, Waris P, Waris V, Tarkiainen I, Karvanen E, Aarnio J, et al. Diagnostic performance of knee ultrasonography for detecting degenerative changes of articular cartilage. Osteoarthritis Cartilage2012;20:376–81. <h3>Disclosure of Interest</h3> None declared