Superoxide dismutase activity in children with chronic liver diseases

Background/Aims: Liver disease in infancy has multiple etiologies. As reactive oxygen intermediates are involved in several types of tissue damage, we have investigated whether different forms of liver disease in infancy are associated with increased free radical generation, using an indirect approach in which superoxide dismutase (a free radical scavenger) activity is determined in the liver tissue. Methods: A total of 48 liver biopsies performed at diagnosis were evaluated retrospectively. Nine infants had biliary atresia, eight Alagille syndrome, seven α1-antitrypsin deficiency and 12 cryptogenic hepatitis. As controls we studied 12 biopsies with normal histology obtained from seven children with portal vein thrombosis and five children who underwent biopsy for management reason but had no liver disease. Superoxide dismutase activity in liver biopsy specimens was measured using the cytochrome C method by spectrophotometry and expressed as U SOD/mg protein. Results: Superoxide dismutase activity was significantly increased in biliary atresia (1.25±0.56 U SOD/mg protein, p<0.0001) and Alagille syndrome (1.31±0.56 U SOD/mg protein, p<0.0001) as compared with α1-antitrypsin deficiency (0.75±0.3 U SOD/mg protein), neonatal hepatitis (0.72±0.37 U. SOD/mg protein) and normal controls (0.4±0.7 U. SOD/mg protein). The highest level of SOD activity was found, however, in control children with portal vein thrombosis (2.09±0.96 U SOD/mg protein; p<0.0001 as compared to the other groups). Conclusion: Superoxide dismutase, a key enzyme in free radical protection, is increased significantly in the liver tissue of infants with cholestatic liver disease due to bile duct damage and in children with portal vein thrombosis, suggesting that products of free radical reactions are involved in the pathogenesis of these disorders.