Oxidative stress as a potential biomarker for determining disease activity in patients with rheumatoid arthritis.

Rheumatoid arthritis is an inflammatory, autoimmune disease where oxidative stress has been proposed to contribute to the joint tissue damage. To establish whether measurement of the redox status in blood mirrors the oxidant status at sites of inflammation in patients with rheumatoid arthritis, we concomitantly examined their oxidant status by spectrophotometry and/or flow cytometry. The basal levels of total reactive oxygen species (ROS), superoxide and hydroxyl radicals were significantly raised in neutrophils sourced from peripheral blood and synovial infiltrate, as also showed a strong positive correlation; however, there was no major increase in the reactive nitrogen species RNS generated in monocytes from both sources. Furthermore, raised levels of superoxide in neutrophils of synovial infiltrate showed a positive correlation with NADPH oxidase activity in synovial fluid. Additionally, as ROS generated in both peripheral blood and synovial infiltrate correlated positively with both DAS 28 and CRP/anti-CCP levels, its measurement can serve as an indirect measure of the degree of inflammation in patients with RA.