To explore the potential roles of Dickkopf-1 (DKK-1) and b-catenin in Crohn disease, and to evaluate the effects of a tumor necrosis factor (TNF)-a inhibitor on Wnt signaling in patients with the disease.
We enrolled 21 patients who received infliximab treatment for one year and achieved clinical remission during the treatment period. Disease activity was graded according to the Pediatric Crohn's Disease Activity Index (PCDAI). Peripheral blood and colonic mucosal specimens were collected from all patients with Crohn disease and from 14 healthy controls. DKK-1 levels in serum were detected by enzyme-linked immunosorbent assay (ELISA). Total RNA for DKK-1 and b-catenin from the frozen colonic tissue were obtained via real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). Serum C-reactive protein (CRP) levels, erythrocyte sedimentation rates (ESR), and albumin were also measured in patients with Crohn disease before and after infliximab therapy.
The serum levels of DKK-1 were significantly higher in patients with Crohn disease than in healthy controls (P=0.003) and were decreased in those treated with infliximab (P=0.026). Serum DKK-1 level was correlated with levels of ESR (r=0.527, P=0.025), CRP (r=0.502, P=0.034), albumin (r=0.363, P=0.021) and PCDAI (r =0.462, P=0.054) in Crohn disease. DKK-1 mRNA expression in the colonic mucosa was higher in patients than in controls and decreased after infliximab treatment. b-catenin expression in the colonic mucosa was lower in patients than in controls and increased after infliximab treatment. However, the differences were not significant (P<0.05).
DKK-1 might be an important mediator of the pathogenesis of Crohn disease, and changes in DKK-1 levels may serve as biomarkers of inflammation in these patients.