Effects of chronic ethanol consumption on cytokine regulation of liver regeneration

Ethanol ingestion may interrupt the proregenerative signal transduction that is initiated by injury-related cytokines such as tumor necrosis factor (TNF)-alpha and TNF-alpha-inducible cytokines including interleukin (IL)-6. To test this theory, liver regeneration, TNF-alpha and IL-6 expression, and cytokine-regulated prereplicative events were compared in ethanol-fed rats and isocalorically fed controls after 70% partial hepatectomy (PH). Ethanol feeding inhibits hepatocyte replication and recovery of liver mass after PH but generally promotes induction of both cytokines in the liver and extrahepatic tissues (i.e., white adipose tissue). Cytokine-regulated events that occur early in the prereplicative period are influenced differentially. TNF-alpha-dependent increases in hepatic nuclear factor-kappa B (NF-kappa B) p50 and p65 expression and DNA binding activity are prevented, whereas IL-6-dependent inductions of hepatic Stat-3 phosphorylation and DNA binding activity occur normally. in contrast, events (e.g., induction of cyclin D1, cdk-1, cyclin D3, and p53 mRNA) that occur at the end of the prereplicative period are uniformly inhibited. These findings indicate that chronic ethanol ingestion arrests the regenerative process during the prereplicative period and demonstrate that increased TNF-alpha, IL-6 and Stat-3 are not sufficient to assure hepatocyte proliferation after PH.