Hepatic fibrosis is the main histological feature that accomExperimental evidence indicates that the lipid peroxipanies the progression of alcoholic liver injury to cirrhosis dation of biological membranes is often associated with in chronic alcohol abusers. 1,2 Acetaldehyde, a potential prothe development of liver fibrosis. We have studied the oxidant factor linked to ethanol metabolism, has been proeffect of neutrophil-derived reactive oxygen species posed as a mediator of fibrogenesis in alcoholic liver disease.
(ROS) on collagen synthesis by human hepatic stellateIn fact, an immunohistochemical association between acetalcells (HSC), the major source of collagen in the liver, in dehyde-protein adducts and extracellular matrix deposition a coculture system. Lipid peroxidation in the cocultures in alcohol-induced liver injury has been reported. of extracellular matrix components in the liver. 6,13-16 When ROS resulted in the early induction of lipid peroxidation isolated and cultured on plastic, they undergo spontaneous and was associated with a marked increase (threefold) transformation into myofibroblast-like cells, thereby mimickof procollagen I mRNA expression and synthesis. The ing in vitro 17 conditions that prevail in vivo after chronic addition of antioxidants, such as vitamin E or superoxalcohol consumption. [18][19][20] However, different mechanisms, ide dismutase (SOD), impaired this stimulation. The other than acetaldehyde-induced fibrogenesis, may be ininhibition of neutrophil NO formation by N G -monovolved in alcoholic hepatic fibrosis. Evidence coming from methyl-L-arginine made the ROS-induced stimulation of either experimental or clinical studies indicates that lipid procollagen I more evident. The addition of xanthine/ peroxidation of biological membranes is often associated with xanthine oxidase X/XO, a superoxide anion donor, to the development of liver fibrosis. [21][22][23][24][25] We have recently shown HSC cultures strongly increased procollagen I synthesis.that the induction of lipid peroxidation phenomena or that This stimulation was hampered by the addition of both treatment with 4-hydroxynonenal (a highly reactive alde-SOD and sodium nitroprusside (an NO donor). The conhydic end-product of lipid peroxidation) stimulates procollatribution of HSC to the production of NO in our coculgen type I synthesis in human HSC by acting at the level ture system was negligible, because inducible NO synof gene expression. 26 Moreover, malondialdehyde has been thase (iNOS) mRNA was almost undetectable in these shown to stimulate collagen production by rat HSC upon acticells, and also because the amount of NO produced by vation in primary culture. 27
HSC stimulated with tumor necrosis factor a (TNF-a)Although alcoholic liver fibrosis may develop in the absence and lipopolysaccharide (LPS) was 500 times less than of evident inflammation, 1,2 the occurrence of alcoholic hepatithat synthesized by neutrophils. In conclusion, these retis may contribute to the increased extracellular matrix deposults ind...