Detection of BRAF in the synovial fluid and its clinical significance in rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective To detect v raf murine sarcoma viral oncogene homologue B1 (BRAF) in the synovial fluid of rheumatoid arthritis (RA) and to investigate its clinical significance in RA.Methods Synovial fluid samples were obtained from patients with RA and osteoarthritis (OA).Serum samples were obtained from patients with RA,OA and heathy controls.The presence of BRAF in the synovial fluid and sera were examined by enzyme-linked immunosorbent assay (ELISA).Western blotting was used to detect the expression of BRAF protein in the synovial tissue of RA and OA.The associations between the BRAF and the clinical features and laboratory parameters of RA were evaluated.Data analysis were performed using t test and Spearman's association analysis.Results ① The level of BRAF in the synovial fluid of RA [(84±59) ng/ml] was significantly higher than OA [(38±41) ng/ml] (t=3.290,P=0.002).② The level of BRAF in the sera of RA patients [(22.0±12.5) ng/ml] was also higher than OA [(6.8±7.5) ng/ml,t=3.882,P＜0.01] and healthy controls [(4.8±2.2) ng/ml,t=6.766,P＜0.01].③ In RA patients,the BRAF protein level in the synovial fluid [(102±52) ng/ml] was significantly higher than that in the serum [(21±12) ng/ml] (t=-4.316,P=0.003).④The expression level of BRAF in the synovial tissue of RA (0.284±0.045) was higher than that in OA patients (0.191±0.013,t=3.169,P=0.034).⑤ The level of BRAF in the synovial fluid had a negative correlation with disease duration (r=-0.40,P=0.019) and a positive correlation with rheumatoid factor (RF) levels (r=0.37,P=0.03).Conclusion The presence of BRAF in the synovial fluid and synovium of RA indicates that BRAF may play a role in the pathogenesis of RA,especially in the early stage.