Abstract: Objective: To investigate the expression of programmed cell death factor 5 ( PDCD5) in patients with rheumatoid arthritis (RA) and to explore its potential role in the pathogenesis of RA. Methods: A total of 36 patients with RA and 35 patients with osteoarthritis (OA) were enrolled, and 33 healthy people were served as controls. PDCD5 and IL-6 levels in serum as well as the levels in synovial fluid were measured by enzyme-linked immunosorbent assay (ELISA). Indices including C reaction protein (CRP), erythrocyte sedimentation rate(ESR), rheumatoid factor(RF）and cyclic citrullinated protein (CCP）were also detected, while count of swollen joints (SJC) and count of tender joints (TJC) served as reference of disease activity were recorded. Results: Compared with OA patients and controls, RA patients had a higher serum level of PDCD5 [（32.47±12.79） ng/mL vs （12.79±9.84） ng/mL in OA and (18.40±18.97） ng/mL in controls]. PDCD5 levels in synovial fluid of RA patients were also higher than those of OA patients. Furthermore, serum level of PDCD5 in RA patients was negatively correlated with IL-6 level in serum, however, no correlation was observed in synovial fluid. Pearson analysis showed that serum PDCD5 level in RA was negatively correlated with CRP, ESR, TJC and SJC (R=-0.523, -0.701, -0.845, -0.943, respectively), but had no correlation with RF and CCP. Conclusions: Serum and synovial levels of PDCD5 could reflect the activity of RA, and its abnormal expression may be associated with level of IL-6.

Key words: Rheumatoid arthritis, Programmed cell death factor 5, Interleukin 6