Inactivation of synovial fluid α1‐antitrypsin by exercise of the inflamed rheumatoid joint

Abstract

α₁-Antitrypsin (α₁AT) is known to be oxidised by reactive oxygen species both in vitro and in vivo, leading to its inactivation. We report here that synovial fluid (SF) α₁AT is inactivated during exercise of the knee-joints of rheumatoid arthritis (RA) patients. Sequential SF sampling from exercised RA patients showed a marked decrease in the mean activity of α₁AT after exercise with no change in the molecular forms of α₁AT. No such inactivation was found in the control (continuously resting) RA patients. We suggest that oxidation may contribute to α₁AT inactivation as a consequence of ‘hypoxic-reperfusion’ injury after exercise of the inflamed joint.