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...

We tested the hypothesis that polymorphonuclear leukocyte (PMN) cell counts and phagocytic activity determined by latex ingestion and superoxide anion production are influenced by different training periods. We investigated long-distance runners before and up to 24 h after a graded exercise test to exhaustion during moderate training (MT) and intense training (IT) and compared them with untrained (control) subjects. Cell counts and phagocytic activity at rest and after exercise did not differ significantly between MT and control. On the contrary, IT showed a significant (P < or = 0.05) decrease in PMN cell count at rest (2.55 +/- 0.3 cells/nl) compared with MT (3.63 +/- 0.2 cells/nl) and control (3.41 +/- 0.8 cells/nl). Furthermore, phagocytic activity was significantly reduced (P < or = 0.05) in IT at rest and after exercise compared with MT and control. A strong inverse correlation (r = -0.75; P < or = 0.01) between epinephrine and superoxide anion production was found. These results provide evidence that the phagocytic activity depends on the training period and indicate impaired PMN functions during IT, which might lead to increased susceptibility to infection.

Excessive urea excretion associated with a negative nitrogen balance and massive loss of skeletal muscle mass (cachexia) is a frequent life threatening complication in malignancies and HIV infection. As these patients have often elevated interleukin-6 (IL-6) and abnormally low cystine levels, we have now determined the intracellular levels of glutathione and other cysteine derivatives in the liver and muscle tissue of IL-6-treated or tumor-bearing C57BL/6 mice. IL-6 treatment or inoculation of the MCA-105 fibrosarcoma caused a significant increase in hepatic gamma-glutamyl-cysteine synthetase activity and a decrease in the sulfate level, glutamine/urea ratio, and glutamine/glutamate ratio, suggesting that a decrease of the proton generating cysteine catabolism in the liver may increase carbamoyl-phosphate synthesis and urea formation at the expense of net glutamine synthesis. Treatment with cysteine, conversely, caused an increase in sulfate, glutamine/urea ratios, and glutamine/glutamate ratios and may thus be a useful therapeutic tool in clinical medicine. In contrast to the liver, muscle tissue of tumor-bearing mice showed decreased glutathione and increased sulfate levels, suggesting that the cysteine pool may be drained by an increased cysteine catabolism in this tissue. The findings indicate that tumor cachexia is triggered initially by IL-6 and is later sustained by processes driven by an abnormal cysteine metabolism in different organs.-Hack, V., Gross, A., Kinscherf, R., Bockstette, M., Fiers, W., Berke, G., and Dröge, W. Abnormal glutathione and sulfate levels after interleukin 6 treatment and in tumor-induced cachexia.

Leucocyte cell counts and the phagocytic and chemotactic activities of neutrophil granulocytes were investigated in highly endurance-trained long-distance runners (n = 10) and triathletes (n = 10) during a moderate training period and compared with untrained subjects (n = 10) before and up to 24 h after a graded exercise to exhaustion on a treadmill. After exercise a leucocytosis was noted with a significant increase in lymphocyte (P < or = 0.01) and neutrophil (P < or = 0.01) counts in all groups. In neutrophils the number of ingested inert latex beads was significantly increased (P < or = 0.01) from 0.21 (SD 0.09) to 0.45 (SD 0.22) in controls, from 0.20 (SD 0.12) to 0.56 (SD 0.16) in long-distance runners and from 0.25 (SD 0.08) to 1.03 (SD 0.42) particles per cell in triathletes 24 h after exercise, compared with resting values. The capability of neutrophils to produce microbicidal reactive oxygen species fell (P < or = 0.05) immediately after exercise in all subjects and then increased by 36 (SD 8)%, 31 (SD 6)% and 19 (SD 9)% in controls, runners and triathletes respectively up to 24 h after exercise (P < or = 0.05) compared with pre-start values. With respect to the absolute number of neutrophils, ingestion capacity, production of superoxide anions and chemotactic activity, no significant differences were found between athletes and control subjects at rest and after exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

To determine the therapeutic effect of sulfur amino acid supplementation in HIV infection we randomized 40 patients with antiretroviral therapy (ART; study 1) and 29 patients without ART (study 2) to treatment for 7 months with N-acetyl-cysteine or placebo at an individually adjusted dose according to a defined scheme. The main outcome measures were the change in immunological parameters including natural killer (NK) cell and T cell functions and the viral load. Both studies showed consistently that N-acetyl-cysteine causes a marked increase in immunological functions and plasma albumin concentrations. The effect of N-acetyl-cysteine on the viral load, in contrast, was not consistent and may warrant further studies. Our findings suggest that the impairment of immunological functions in HIV+ patients results at least partly from cysteine deficiency. Because immune reconstitution is a widely accepted aim of HIV treatment, N-acetyl-cysteine treatment may be recommended for patients with and without ART. Our previous report on the massive loss of sulfur in HIV-infected subjects and the present demonstration of the immunoreconstituting effect of cysteine supplementation indicate that the HIV-induced cysteine depletion is a novel mechanism by which a virus destroys the immune defense of the host and escapes immune elimination.

Patients with skeletal muscle catabolism (cachexia) fail to conserve the skeletal muscle protein and release large amounts of nitrogen as urea. Previous studies suggest that the threshold for the conversion of amino acids into other forms of chemical energy and the concomitant production of urea are regulated by the plasma cystine level and hepatic cysteine catabolism. Studies of plasma amino acid exchange rates in the lower extremities now show that healthy young subjects regulate their plasma cystine level in a process that may be described as controlled constructive catabolism. The term controlled describes the fact that the release of cystine and other amino acids from the peripheral tissue is negatively correlated with (certain) plasma amino acid levels. The term constructive describes the fact that the release of cystine is correlated with an increase of the plasma cystine level. The regulation of the plasma cystine level is disturbed in conditions with progressive skeletal muscle catabolism including cancer, HIV infection, and old age. These conditions show also a low plasma glutamine:cystine ratio indicative of an impaired hepatic cystine catabolism. In HIV+ patients and SIV-infected macaques, a decrease of the plasma cystine level was found to coincide with the decrease of CD4+ T cells.