ABSTRACT
Objective To investigate the relationship between abnormal metabolism of aggrecan and joint destruction in patients with rheumatoid arthritis (RA).Methods 140 RA patients with duration less than 24 months were enrolled into this study.The study also included 100 normal controls and 95 patients with other rheumatic diseases.Three monoclonal antibodies (5D4,7D4 and BC-3) of aggrecan were used to detected aggrecan catabolic fragments in serum of RA patients and the other two groups of controls by enzyme linked immunosorbent assay (ELISA),and the correlation of aggrecan catabolic fragments with joint damage were analyzed.Sharp evaluation of hand joints in RA patients were performed at baseline and after one year follow-up.Calculating the area under the receiver operating characteristic curve (ROC) was used to evaluate the sensitivity and specificity of aggrecan catabolic fragments detected in serum of RA patients.Results Both levels of 5D4 fragment and BC-3 fragment of RA group were higher than those of normal control [5D4 of RA:(5.8±2.1) ng/μl,normal control:(2.2±1.3) ng/μl;BC-3 of RA:(11.1±3.4) ng/μl,normal control:(5.0±2.1) ng/μl,F=38.65,24.07,P＜0.001).There was no difference in 7D4 fragment among three groups (F=0.589,P=0.478).Both two fragment levels of RA patients with anti-CCP positive were greater than those patients with anti-CCP negative [5D4:(5.6±1.3) ng/μl vs (4.4±1.1) ng/μl,F=21.23,P＜0.01;BC-3:(12.2±3.9) ng/μl vs (9.3±2.8) ng/μ1,F=27.14,P＜0.01].Linear Regression showed that serum fragments detected by 5D4 and BC-3,and anti-CCP positive were risk factors for Sharp deterioration after one year follow-up.The sensitivity and specificity of combined detection of two aggrecan fragments in serum of RA patients for the prediction of joint Sharp were 56.5％ and 84.2％ respectively.Positive predictive value and negative predictive value are 74.3％ and 70.6％.respectively.Application of areas of ROC to identify the best evaluation of Sharp was 0.798.Conclusion There is positive correlation between aggrecan catabolic fragments in serum and joint Sharp evaluation of RA patients.Detection of aggrecan catabolic fragments in RA patients may predict early joint destruction.