Oxidative stress, as measured by protein oxidation, is increased in primary Sjøgren's syndrome

Oxidative stress is an imbalance between the production of reactive oxygen species (ROS) and physiological antioxidant defences. It occurs frequently in conditions characterized by immune activation and inflammation. Plasma levels of oxidized end products have never been evaluated in primary Sjøgren's syndrome (pSS). The aim of this study was to investigate the level of oxidative stress in primary Sjøgren's syndrome. As a secondary outcome, the association between oxidative stress and fatigue was explored.A cross-sectional study of 26 pSS patients was carried out. Oxidative stress was assessed using two markers of protein oxidation, protein carbonyl (PC) and advanced oxidation protein products (AOPP). Reference values for the oxidative stress markers were obtained from 15 healthy subjects.AOPP and PC levels were increased in the pSS patients compared to the healthy subjects. This is a novel finding. There were no associations between oxidative stress measures and fatigue in the patients.Patients with pSS have increased levels of oxidative stress compared to healthy subjects.