Background In order to assess disease activity and predict outcomes of patients with spondyloarthritis (SpA), it is necessary to discover useful serum biomarker reflecting inflammation, fat deposition, erosion and ankylosis . GDF15 was previously fond related to inflammation  and worked as a protective factor in inflammatory pathology. In rheumatology arthritis patients, serum level of GDF15 could predict the presence of joint erosions .
Objectives The objective was to assess associations between GDF15 and radiographic features, including X-ray and MRI of the sacroiliac joint in SpA patients.
Methods SpA was defined according to 2009 ASAS criteria. Sera from 53 patients with SpA and 18 healthy controls were measured GDF15 levels using ELISA. Inflammation was assessed by ESR, CRP and MRI of the SIJ, using the Spondyloarthritis Research Consortium of Canada (SPARCC) score and a method of dichotomy to assess fat deposition, bone erosion and ankylosis. Radiographs of the pelvis were scored by using the modified New York (mNY) score.
Results Serum GDF15 levels were higher in SpA patients in comparison with controls (208.4 ± 173.7 vs 339.2 ± 295.0 pg/ml and P=0.005 Figure). Among SpA, patients who suffered from bone erosion on MRI had lower levels of GDF15 (423.4± 288.1 vs 284.3± 275.6 pg/ml and P=0.022).In addition, correlation analysis showed there was a negative correlation between serum GDF15 and bone erosion (r= -0.433, p=0.007) in SpA patients whose X-rays were 0-III according to mNY criteria. Moreover, GDF15 levels of those patients were related to CRP levels ((r=0.328, p=0.044). No significant correlations were found between SPARCC score, fat deposition and ankylosis and GDF15 levels, but CRP and ESR levels were significantly correlated with SPARCC score (r=0.291, p=0.036 and r=0.474, p=0.0004) in SpA.
Conclusions Our study suggested that serum GDF15 levels were higher in SpA patients than healthy controls.GDF15 was correlated with CRP which was correlated with SPARCC score, suggesting GDF15 may not directly related to bone edema in SpA. GDF15 was negatively related to bone erosion, which may play a protective role in process of bone erosion.
Maksymowych W.P., Biomarkers in axial spondyloarthritis. Curr Opin Rheumatol, 2015. 27(4): p. 343–8.
Lindahl B., The story of growth differentiation factor 15: another piece of the puzzle. Clin Chem, 2013. 59(11): p. 1550–2.
Brown, D.A., et al., Serum macrophage inhibitory cytokine 1 in rheumatoid arthritis: a potential marker of erosive joint destruction. Arthritis Rheum, 2007. 56(3): p. 753–64.
Disclosure of Interest None declared