Role of reactive oxygen and nitrogen species in etiopathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic disease affecting up to 3% of the po pulation in most countries. The causes of Re have not been completely eluci dated. This paper aims to review the role of reactive oxygen and nitrogen s pecies in the etiopathogenesis of RA. Reactive oxygen species (ROS), such a s superoxide radical, hydrogen peroxide, hydroxyl radical and hypochlorous acid, as well as reactive nitrogen species (RNS), such as nitric oxide and peroxynitrite, contribute significantly to tissue injury in RA. Several mec hanisms are involved in the generation and action of ROS and RNS. Superoxid e radical, hydrogen peroxide and nitric oxide do not directly damage the ma jority of biological molecules. They are however converted into the highly reactive hydroxyl radical, which reacts with almost all molecules in living cells. The resulting chronic inflammation process can be reduced with anti oxidant therapy. To date, scavenging, preventive, and enzyme antioxidants a re available. The most important mode is scavenging of the hydroxyl radical and of hypochlorous acid. Another important way is to inhibit production o f RNS and ROS by neutrophils, monocytes, and macrophages. The control of in flammation in arthritic patients by natural as well as synthetic antioxidan ts could become a relevant component of antirheumatic prevention and therap y.