WNT /β -catenine signal pathway activitiy in sjögren's syndrome

Sjögren's syndrome (SS) is a progressing autoimmune disease characterized by salivary and lacrimal gland dysfunction, resulting in oral and ocular dryness. The pathogenesis of SS is still unknown. The canonical Wnt/β-catenin pathway has been recently shown to play an important role in inflammation. We aimed to determine serum and salivary levels of Dickkopf-related protein 1 (DKK1) and sclerostin those are Wnt signaling mediators and Immunohistochemically evaluating Wnt1, Wnt3a expressions in the salivary glandin patients with primary SS. 30 patients with SS, 30 patients with SLE and 29 healthy controls were enrolled in the study for determine serum and salivary levels of Dickkopf-related protein 1 (DKK1) and sclerostin. And Wnt1, Wnt3a expressions from salivary gland tissue specimens in the pathology archive of 12 patients (patology control group) without SS diagnosis were taken to be evaluated immunohistochemically. Fasting blood and saliva samples were obtained from the participants. Serum and salivary levels of DKK and sclerostin were measured by enzyme-linked immunosorbent assay. ESSDAI and SLEDAI scores were calculated and recorded in patient groups. Patients with SS had lower serum DKK1 and sclerostin levels compared to the healty controls (p<0.001 for both). However, salivary DKK1 and sclerostin levels were not lower. Serum DKK1 and sclerostin levels were lower in SLE patients compared to the healty controls (p<0.001 for both). However, their salivary levels were similar in SLE and healty control groups. When SS and SLE groups were compared, there was a significant difference between serum and salivary DKK1 levels (p values p:0.046 and p:0.009, respectively). However, there was no significant difference between serum and salivary sclerostin levels (p values 0,9 and 0,9 respectively). There were no significant differences in Wnt1, Wnt3a negativity in tissue specimens in SS and control group pathology archives (p>0,05). Serum and salivary DKK1 and sclerostin levels were not significantly different between Wnt1 and Wnt3a positives and negatives (p>0.05). Serum levels of DKK1 and sclerostin are decreased in primary SS. These results suggest that Wnt pathway may be down-regulated in SS. Key words: Sjögren's syndrome, Wnt, sclerostin, DKK1