Background: Oxidative stress contributes to the propagation and exacerbation of inflammatory bowel disease (IBD) but the status of erythrocyte antioxidant defense remains unknown.
Methods: Erythrocyte activities of superoxide dismutase-1 (SOD1), catalase, and glutathione peroxidase-1 (GPx1) were determined in 174 IBD patients and 105 controls and referred to IBD activity, inflammation severity, nutritional status, systemic oxidative stress, anemia, and treatment.
Results: Catalase and GPx1 activities were decreased in active IBD, whereas SOD1 became upregulated by IBD-related oxidative stress. In Crohn's disease (CD) corticosteroids decreased SOD1 activity. SOD1 correlated indirectly with CD activity and erythrocyte sedimentation rate (ESR) and directly with transferrin. In ulcerative colitis (UC) anemia downregulated SOD1. Decreases in GPx activity corresponded with IBD activity, anemia, inflammation, and malnutrition. Oxidative stress in UC and corticosteroids in CD also downregulated GPx. Catalase activity was decreased by CD-related anemia, correlating directly with hemoglobin, and indirectly with CD activity, inflammatory and protein oxidative stress markers. When co-analyzed, anemia but not CD activity significantly contributed to catalase downregulation. In UC, catalase activity corresponded indirectly with UC endoscopic activity and inflammation and directly with hemoglobin. UC activity, anemia, and treatment with azathioprine negatively affected catalase. As indicators of active IBD, GPx1 showed a diagnostic accuracy of 73%, whereas catalase showed 63% as compared to 74% of C-reactive protein and ESR.
Conclusions: Erythrocyte antioxidant defense is impaired in active IBD. SOD1, GPx1, and CAT activities are differently affected by the disease type, activity, anemia, inflammation, oxidative stress, and treatment. As an active IBD indicator, GPx1 was comparable to C-reactive protein and ESR.