Background : Psoriatic arthritis (PsA) is a chronic inflammatory disease. It is characteristically associated both peripheral (arthritis, enthesitis and dactylitis) and axial skeletal involvement. A range of bone pathologies is common in PsA. Bone loss, either locally (erosions) or systemically, may present. Additionally, new bone formation may also occur in both peripheral and axial skeletons. However, molecular mechanisms underlying these processes have not yet been fully understood. Secreted Wnt receptor antagonists, dickkopf-1(Dkk-1) and sclerostin, are negative regulators of bone formation. And it has been shown that periostin, as a matricellular protein, is involved in the early stages of osteoblast differentiation and bone formation. Therefore the aim of the present study was to evaluate bone formation markers in patients with with PsA.Methods: In total 70 consecutive PsA patients [49 females (69%); with a median age (interquartile range, IQR) of 43 (17) years] according to the CASPAR criteria, 35 psoriasis patients [ 15 females (%42); with a median age (IQR) 44(20) years] and 36 healthy control subjects [(23 females [63%]; with a median age (IQR) 38 (16) years] were included in the study. Serum periostin, Dkk-1 and sclerostin levels were measured by commercially available ELISA kits. We also assessed serum levels of high-sensitivity C-reactive protein (hs-CRP). Disease related characteristics of patients were evaluated by using BASDAI, BASFI, HAQ, DAS28. Because the data were not distributed homogenously the results are presented as median and interquartile range (IQR) and non-parametric tests were used for group comparisons.Results: In our PsA group, median (IQR) duration of psoriasis and psoriatic arthritis were 13(20) and 6 (8) years, respectively. In total 27 patients were using corticosteroids, 41 metothrexate, 12 leflunomide and 23 tumor necrosis factor inhibitors. Some of the clinical and laboratory characteristics of patients and control subjects were shown in table. As expected serum CRP levels were significantly higher in PsA patients in comparison with control subjects. Serum periostin levels were not statistically different between study groups. However, we found that circulating Dkk-1 and sclerostin levels were significantly lower in PsA patients. Serum Dkk-1 levels were associated with serum sclerostin levels (r=0.872 and P<0.001) and age (r=0.312 and P=0.008). Serum periostin, Dkk-1 and sclerostin levels were not different between PsA patients with and without axial incolvement. Conclusion: Our results suggested that circulating Dkk-1 and sclerostin may have a role in disease susceptibility. Decreased Dkk-1 and sclerostin levels may contribute to the new bone formation, seen in the disease course, in patients with PsA. Periostin have no any significant relationship between PsA, psoriasis and control groups.

Giriş: Psöriatik Artrit (PsA) kronik inflamatuar bir hastalıktır. Karakteristik olarak aksiyal ve periferal (artrit, entezit ve daktilit) eklemlerin ikisini birden tutabilir. Kemik kaybı bu hastalıkta hem sistemik hem de local faktörler ile olmaktadır. Ek olarak yeni kemik formasyonu hem periferal hem de aksiyal iskelette gözlenmektedir. Bütün bu süreçlerde rol alan mekanizmalar ise tam olarak aydınlatılamamıştır. Periostin ise osteoblast diferansiasyonunda ve kemik formasyonunda erken dönemlerde gözlenen bir matriselüler proteindir. Bu çalışmada kemik formasyonu üzerine periostin ve çeşitli belirteçleri araştırmayı amaçladık. Yöntem: Toplamda 70 PsA [49 kadın (%69), median yaş (interquartile range-IQR) 43 (17 yıl)], 35 psöriazis [15 kadın (%42), median yaş (IQR) 44(20)] ve 36 sağlıklı kontrol grubu [23 kadın (%63), median yaş (IQR) 38(16)] çalışmaya dahil edildi. Serum periostin, Dkk-1 ve sklerostin serviyeleri ELİSA kiti ile ölçüldü. Aynı zamanda hastalardan high sensitive C-reactive protein (hs-CRP) ölçümü alındı. Hastalık ilişkili değerlendirme amacıyla BASDAI, BASFI, HAQ, DAS28 ölçümleri yapıldı. Veriler heterojen dağılması nedeniyle sonuçlar median ve interquartile range olarak verildi, grup karşılaştırmalarında non parametrik testler kullanıldı.Bulgular: PsA grubunda, psöriazis median (IQR) süresi 13 (20), psöriatik artrit median süresi (IQR) 6 (8) yıl idi. Psoriazis hastalarında psoriazisin median süresi (IQR) 10 (11) yıl idi. Toplamda 27 hasta kortikosteroid, 4 hasta methotrexate, 12 hasta leflunomide ve 23 hasta tumor nekrozis faktör alfa inhibitörleri kullanmakta idi. Serum periostin düzeylerinde her iki grup arasında istatistiki anlamlı bir farklılık saptanmadı. Serum DKK-1 ve sklerostin düzeyleri iste PsA ve psöriatik artrit hastalarında kontrol grubuna kıyasla istatistiki anlamlı düşük saptandı.Tartışma: Azalmış DKK-1 ve sklerostin sevieyeleri PsA ve psorizasis hastalarında tespit olup bu belirteçler aktif inflamasyon ve yeni kemik oluşumu ile ilgili olabilir.