Alcohol and Alcoholism Vol. 35, No. 3, pp. 230-235, 2000
© 2000 Medical Council on Alcoholism
ACTIVATED MACROPHAGES INCREASE THE SUSCEPTIBILITY OF RAT HEPATOCYTES TO ETHANOL-INDUCED OXIDATIVE STRESS: CONFLICTING EFFECTS OF NITRIC OXIDE
Laboratoire de Biologie Cellulaire et Végétale et INSERM U456, UFR des Sciences Pharmaceutiques et Biologiques, 2 av. Pr. Léon Bernard, 35043 Rennes Cedex, France
Received 12 July 1999; first review notified 25 October 1999; accepted 20 November 1999
The aim of this study was to examine how macrophages could act on ethanol-induced oxidative stress in rat hepatocytes during inflammatory conditions, well-known to induce nitric oxide (NO) synthase. For this purpose, RAW 264.7 macrophages were added to primary rat hepatocyte cultures. Co-cultures were then supplemented with lipopolysaccharide (LPS) and interferon
(IFN) for 18 h, in order to induce NO synthase before the addition of 50 mM ethanol. In cultures of hepatocytes alone, the addition of LPS and IFN protected from ethanol-induced oxidative stress. It has been shown previously that NO generated in hepatocytes was responsible for this effect. When macrophages were added to primary rat hepatocyte cultures supplemented with LPS and IFN, protection provided by NO against ethanol-induced oxidative stress in hepatocytes ceased. Using a pretreatment of macrophages with Ng-monomethyl-l-arginine, a NO synthase inhibitor, it was concluded that NO generated by macrophages was responsible for macrophage toxicity. Taken together, our observations suggest that NO biosynthesis in hepatocytes protects them from ethanol-induced oxidative stress, whereas NO production in macrophages deprives hepatocytes of this NO protection.