Serum and synovial fluid 14-3-3η protein in patients with primary knee osteoarthritis compared with rheumatoid arthritis: relation to functional status and radiographic damage

Aim of the workThe aim of the present work was to examine the association between 14-3-3η protein levels in both serum and synovial fluid (SF) with radiographic damage and physical function in patients with primary knee osteoarthritis (OA) compared with rheumatoid arthritis (RA) patients.Patients and methodsThis is a cross-sectional study that involved two groups: group 1 included 50 primary knee OA patients, and group 2 included 50 RA patients. All study patients were assessed for serum and SF levels of 14-3-3η protein that was measured through ELISA technique. Functional assessment of OA patients was done using Western Ontario and McMaster Osteoarthritis index (WOMAC). Radiological assessment was evaluated using Kellgren–Lawrence (KL) grading scale.ResultsThe mean age of OA patients was 51.7 ± 10.4 years, disease duration was 24.8 ± 5.2 months, and mean WOMAC and KL grading scores were 18.5 ± 6.5 and 2.0 ± 0.99, respectively. Serum and SF 14-3-3η protein was significantly higher among RA compared with OA (1.5 ± 0.51 and 3.6 ± 1.1 ng/ml vs. 0.24 ± 0.03 and 0.24 ± 0.03, P = 0.004 and 0.018, respectively). There were no significant differences in serum and SF 14-3-3η protein between male and female OA patients (P = 0.99 and 0.87, respectively). A significant correlation was found between serum levels of 14-3-3η and erythrocyte sedimentation rate (r = 0.49, P = 0.014). The correlations between 14-3-3η protein in OA patients with WOMAC and KL grading scale were weak and not significant (P > 0.05).Conclusions14-3-3η protein levels were significantly lower in OA patients compared with RA patients. Although 14-3-3η levels were significantly correlated with inflammation, there was no correlation with functional status or radiological damage in knee OA patients.