Increased DNA damage and oxidative stress in patients with rheumatoid arthritis

OBJECTIVES: Oxidative stress has been described as an important mechanism that underlies chronic inflammation in rheumatoid arthritis (RA). The aim of the study was to investigate the peripheral DNA damage, total antioxidant status (TAS), and total oxidative status (TOS) in patients with RA. DESIGN AND METHODS: The study population contained 25 patients with RA and 26 healthy controls. DNA damage was assessed by alkaline comet assay in peripheral lymphocyte, plasma levels of total antioxidant status (TAS) and total oxidative status (TOS) were determined, and OSI was calculated using a novel automated measurement method. Disease activity was evaluated by DAS-28 score. RESULTS: In RA patients, DNA damage was significantly higher than in controls (20.0+/-9.6 AU, 7.6+/-4.3 AU; p<0.001). Plasma TOS and OSI were higher in patients than in healthy controls (9.9+/-2.6 vs. 7.3+/-1.1, p<0.001; 1.04+/-0.4 vs. 0.7+/-0.1, p<0.001, respectively). Plasma TAS level in patients was lower than in healthy controls (0.9+/-0.7 vs. 1.01+/-0.7, p<0.001). DNA damage was correlated with TOS, OSI, and DAS-28 scores (r=0.682, p<0.001; r=0.753, p<0.001; r=0.519, p=0.008, respectively). CONCLUSIONS: The findings indicated that lymphocyte DNA damage level increases in patients with RA. Elevated DNA damage may be related with increased oxidative stress and decreased antioxidant capacity. However, the mechanism of this association, and whether it is direct or indirect, remains to be explored.