Background HLA-B27 is strongly associated with the development of spondyloarthritis (SPA), a disease characterized by new bone formation and ankylosis of joints and intervertebral spaces. We have recently shown the role of the two Wnt antagonists, dickkopf 1 (Dkk1) and sclerostin in new bone formation in SPA. We therefore hypothesized that HLA-B27 itself may be associated with alterations in expression of Dkk1 and sclerostin.
Objectives To test whether positivity for HLA-B27 per se is associated with changes of biomarkers of the Wnt pathway.
Methods Sera of 31 patients with HLA-B27 positive SPA, 30 patients with HLA-B27 positive uveitis, 30 healthy carriers of HLA-B27 as well as 90 age and gender matched HLA-B27 negative healthy controls were examined for total Dkk1 and sclerostin levels by enzyme-linked immunosorbent assays (ELISA). Statistical analysis was done by one-way analysis of variance (ANOVA).
Results Healthy HLA-B27 positive individuals showed significant lower levels of Dkk-1 compared with the negative controls (p=0.01). Moreover, Dkk1 levels were reduced in all three HLA-B27 positive groups, even in healthy HLA-B27 carriers. Additionally, serum levels of sclerostin were higher in HLA-B27 negative controls than in SPA HLA-B27 carriers.
Conclusions HLA-B27 positivity is associated with low levels of Dkk1 and sclerostin independent from the presence of clinical symptoms of SPA. Both HLA-B27 healthy carriers as well as HLA-B27 associated uveitis without SPA show lower levels of these two Wnt antagonists than normal HLA-B27 negative controls. These data suggest that alterations in bone metabolism even occur in the absence of clinical SPA and are associated with HLA-B27 carriage.
Disclosure of Interest None Declared