Assessment of bone morphogenic protein 2 and interleukine-17A in patients with axial spondyloarthritis and their potential role in the new bone formation: a cross-sectional study

OBJECTIVES: Several molecules are involved in the pathogenesis of new bone formation in axial spondyloarthritis (axSpA). The aim of this study was to evaluate the serum levels of BMP-2 and IL-17A in patients with axSpA and their possible correlations with radiographic damage, disease activity, and function. METHODS: AxSpA patients fulfilled the ASAS criteria and with at least New York grade 2 bilateral sacroiliitis and healthy matched controls were enrolled for this study. BASDAI, ASDAS-CRP, BASMI, BASFI and CRP were evaluated as measures of disease activity and function. Spinal damage was assessed using the mSASSS on radiographs performed within 3 months from baseline. Serum concentrations of BMP-2 and IL-17A were assessed using ELISA kit. RESULTS: Sixty patients and 30 healthy subjects satisfying the inclusion criteria were enrolled. In our axSpA group, serum BMP-2 levels [median (25th-75th percentile) of 589.2 (430.24-1017.1) pg/ml] did not statistically differ from controls [518.34 (450.2-1028.2) pg/ml]. However, significant correlations were found between serum BMP-2 levels and radiographic damage assessed by mSASSS, and BMP-2 levels were found to be higher in patients with grade 4 sacroiliitis when compared to patients with lower grade of sacroiliitis. Of note, serum BMP-2 levels significantly inversely correlate with IL-17A levels and CRP, and were found to be lower in patients with higher disease activity. CONCLUSIONS: The results of our study may confirm a possible role of BMP-2 in the pathogenesis of new bone formation in axSpA patients. Furthermore, a link between inflammation and BMP-2 was found.