Background/Purpose:

Rheumatoid arthritis (RA) is a chronic inflammatory disease that results in severe joint

damage and physical disability, therefore, the discovery of new marker(s) for joint

destruction is needed. Serum 14-3-3η protein is a novel diagnostic marker for RA, and

also involved in joint damage (1, 2). 14-3-3η protein has been reported to be expressed at

significantly higher levels in synovial fluid (SF) of RA patients when compared with

matched serum by immunoblot analysis (1). Correlation of serum 14-3-3η protein with

clinical variables, autoantibodies, inflammatory markers, and radiologic damage has

been examined in RA (2). These associations have never been examined for RA

synovial fluid (SF) 14-3-3η protein. In this study, we quantified SF 14-3-3η by ELISA

and determined the association of serum and SF14-3-3η protein with clinical, laboratory

and radiographic damage in RA.

Methods:

RA patients diagnosed according to 2010 ACR criteria were included. Serum and SF

samples were obtained from all patients at the same day and 14-3-3η protein levels

were measured using the quantitative 14-3-3η ELISA kit (Augurex Life Sciences Corp).

A 14-3-3η cut-off of ≥ 0.19 ng/ml, the diagnostic cut-off was employed. Radiological

damage was evaluated using Sharp/van der Heijde score (SHS). Spearman or Pearson

correlations to compare relationships and Mann-Whitney U test for groups difference

were used for statistical analysis.

Results:

A total of 39 RA patients, mean age of 38 years, with 87.2% being female were

included. Their mean disease duration was 9.3 years, and 48.7% of patients had

moderate DAS28. Mean SF14-3-3η protein levels were 2 fold higher than mean serum

protein levels (3.7 vs 1.7 ng/ ml). The prevalence of 14-3-3η protein positivity was

higher in SF compared with serum from RA patients; 82.1% versus 69.2%, respectively.

Although there was significant correlation between SF 14-3-3η protein levels and ESR

(p=0.036), no significant association was found between serum or SF 14-3-3η protein

levels with DAS28 or autoantibodies in RA. There was significant correlation between

serum and SF 14-3-3η protein levels (p<0.05) in RA patients. Serum and SF 14-3-3η

protein levels were positively correlated with SHS (p<0.001). RA patients who were

serum or SF 14-3-3η protein positive showed significant difference in SHS but not in

clinical and laboratory features when compared with 14-3-3η negative patients.

Conclusion:

14-3-3η levels are significantly higher in SF than in matched serum. Serum and SF14-3-

3η protein levels correlate with radiographic damage. This study further substantiates

14-3-3η as a mechanistic joint damage marker for RA.

References:

1. Kilani et al. J Rheumatology 2007, 34 (8).

2. Maksymowych et al. Arthritis Research Therapy 2014,16: R99.

« Back to 2017 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-synovial-fluid-14-3-3%ce%b7-protein-as-a-marker-of-joint-damage-in-rheumatoid-arthritis-patients/