Localization of Xanthine Oxido-Reductase to Microvessel Endothelium in the Synovium

Abstract

There is no doubt that the inflamed rheumatoid synovium incorporates an oxygen radical generating system. The evidence for this is based upon studies which show that synovial fluid effusions contain lipid peroxidation products, oxidatively damaged IgG and products of oxidative carbohydrate degradation. In rheumatoid arthritis the synovial fluid and adjacent synovium are hypoxic, minimising the likelihood that radical generation is via the respiratory burst of activated inflammatory cells. An alternative mechanism involving ischaemic/reperfusion has been proposed. The unique topography of the component parts of the joint predispose the synovium to pressure induced fluctuations in the blood supply, creating the environment for ischaemic/reperfusioninjury.