Oxygen free radicals and antioxidants in cystic fibrosis: the concept of an oxidant-antioxidant imbalance

Patients with cystic fibrosis frequently exhibit increased oxygen free radical generation from activated neutrophils due to chronic lung inflammation on the one hand and antioxidant deficiencies due to exocrine pancreatic insufficiency on the other, resulting in an oxidant–antioxidant imbalance in favor of the former. As a consequence, free radical attack on unsaturated fatty acids of lipid structures leading to lipid peroxidation and damaging effects on proteins may occur. In the lung, antiproteases are thought to be inactivated by oxygen free radicals released from inflammatory cells. In the cholestatic liver, bile acids may propagate lipid peroxidation. An efficient antioxidant supply is suggested to control tissue injury by restoring the oxidant-antioxidant balance. Mechanisms involved in the generation of oxygen free radicals are described and data on the antioxidant defense system in cystic fibrosis patients are presented, together with evidence of increased lipid peroxidation. Possible implications for disease processes are discussed as well as therapeutic concepts to reconstitute the oxidant-antioxidant balance.