Background-Reactive oxygen species contribute to tissue injury in inflammatory bowel disease (IBD). The tripeptide glutathione (GSH) is the most important intracellular antioxidant. Aims-To investigate constituent amino acid plasma levels and the GSH redox status in diVerent compartments in IBD with emphasis on intestinal GSH synthesis in Crohn's disease. Methods-Precursor amino acid levels were analysed in plasma and intestinal mucosa. Reduced (rGSH) and oxidised glutathione (GSSG) were determined enzymatically in peripheral blood mononuclear cells (PBMC), red blood cells (RBC), muscle, and in non-inflamed and inflamed ileum mucosa. Mucosal enzyme activity of -glutamylcysteine synthetase ( GCS) and -glutamyl transferase ( GT) was analysed. Blood of healthy subjects and normal mucosa from a bowel segment resected for tumour growth were used as controls. ). The GSH content was unchanged in PBMC, RBC, and muscle. Conclusions-Decreased activity of key enzymes involved in GSH synthesis accompanied by a decreased availability of cyst(e)ine for GSH synthesis contribute to mucosal GSH deficiency in IBD. As the impaired mucosal antioxidative capacity may further promote oxidative damage, GSH deficiency might be a target for therapeutic intervention in IBD. (Gut 1998;42:485-492) Results-Abnormally

Wilson's disease can result in fulminant liver failure due to hepatic copper overload. The CD95 system mediates apoptosis and has been demonstrated to be involved in liver disease. In this study CD95 mediated apoptosis was investigated in patients with fulminant hepatic failure in the course of Wilson's disease and in an in vitro model of copper treated human hepatoma cells. In patients, hepatic expression of CD95 and CD95L mRNA and apoptosis were detected. Copper overload in vitro resulted in hepatocytic apoptosis which could be reduced with a neutralizing anti-CD95L antibody. Copper treatment of hepatocytes results in activation of the CD95 system and induction of apoptosis which is operative during the course of hepatic failure in acute Wilson's disease.

Oxidative stress has been associated with the induction of programmed cell death. The CD95 ligand/receptor system is a specific mediator of apoptosis. We have used the model of drug-induced apoptosis to assess whether the CD95 ligand mRNA is induced by reactive oxygen intermediates. Treatment of HepG2 hepatoma cells with bleomycin induced the production of reactive oxygen intermediates and, as an additional parameter of oxidative stress, resulted in glutathione (GSH) depletion. In parallel, CD95 ligand mRNA expression was induced. In a similar fashion CD95 ligand mRNA expression increased after treatment with H 2 O 2 . Additional treatment with the antioxidant and GSH precursor Nacetylcysteine resulted in partial restoration of intracellular GSH levels and in reduced induction of CD95 ligand mRNA. Induction of CD95 ligand mRNA by bleomycin was further reduced by combined treatment with N-acetylcysteine and deferoxamine. These data suggest a direct role of oxygen radicals in the induction of the CD95 ligand.CD95 (APO-1/Fas) is a 45-kDa glycosylated transmembrane protein belonging to the tumor necrosis factor receptor family of type I membrane proteins (1, 2). The CD95 ligand (CD95L) is a 40-kDa Type II transmembrane protein and a member of the tumor necrosis factor family of cytokines (1, 3). In addition to the transmembrane form, a soluble form of the CD95L exists (4). Binding of the CD95L to its receptor CD95 induces apoptosis. The CD95/CD95L system plays a role in the deletion of T lymphocytes in the peripheral immune system, in the shutting off of an immune response, in T lymphocyte-mediated cytotoxicity, and in the elimination of CD95-expressing leukocytes in immune privileged sites (5-10).CD95 signaling occurs through the death-inducing signaling complex and the activation of a cascade of interleukin converting enzyme/Ced3 proteases (11, 12), which are now designated caspases (13). A cell expressing both CD95 and CD95L undergoes suicide or can cause fratricide (5, 6). CD95L is expressed in activated T lymphocytes (3) but its expression can also be induced by cytostatic agents in a variety of different cell lines (14,15). Furthermore, CD95L expression has been observed in hepatocytes in vivo in patients with alcoholic hepatitis (16). Thus, CD95L expression seems to be induced by different mechanisms of cellular injury and might be an important tool for the organism to eliminate damaged cells. Little is known about the exact mechanism of induction of CD95L.The CD95L promoter has been described to contain NF-B binding sites (17). Therefore, induction of CD95L mRNA might involve reactive oxygen species (ROS).1 In line with this assumption is the observation of apoptotic cell death in different cell lines after oxidative stress (18,19). In the present study we have used the model of bleomycin-induced apoptosis to investigate the possible role of ROS in the induction of CD95L mRNA. Bleomycin has been described as a potent inducer of apoptosis, involving up-regulation of CD95 receptor and ligand expression (15). W...