Prolonged ethanol treatment enhances lipopolysaccharide/phorbol myristate acetate-induced tumor necrosis factor-alpha production in human monocytic cells

Alcohol Clin Exp Res. 2001 Mar;25(3):444-9.


Background: Ethanol (EtOH) is known to alter host immune responses and cytokine production. Acute EtOH exposure can suppress tumor necrosis factor (TNF)-alpha production, which attenuates pulmonary defense against infection. Previous studies in our laboratory show that acute EtOH inhibited TNF-alpha production by a posttranscriptional process, namely suppression of TNF-alpha-converting, enzyme-mediated, ectodomain shedding. However, chronic EtOH has been shown to augment TNF-alpha production, and this has been associated with EtOH-induced liver injury. To further characterize this paradoxical effect of EtOH on TNF-alpha production, we developed an in vitro model by using Mono Mac 6 cells, a human monocytic cell line.

Methods: Mono Mac 6 cells were treated with EtOH (0-75 mM) for 1 to 7 days. TNF-alpha production was induced by lipopolysaccharide and phorbol myristate acetate and quantitated by enzyme-linked immunosorbent assay. Generation of reactive oxygen species (ROS) was assayed by using a specific fluorogenic reagent.

Results: Acute EtOH initially inhibited lipopolysaccharide/phorbol myristate acetate-induced TNF-alpha production in Mono Mac 6 cells. However, during chronic EtOH exposure, this inhibition was reversed gradually over time. By day 6 after EtOH treatment, Mono Mac 6 cells demonstrated significant up-regulation of TNF-alpha production. Moreover, chronic EtOH induced the generation of ROS in these Mono Mac 6 cells. Scavenging ROS by Mn(III)tetrakis(1-methyl-4pyridyl)porphyrin pentachloride and N-acetyl-L-cysteine attenuated chronic EtOH-enhanced TNF-alpha production.

Conclusion: These results suggest that ROS induction is involved in EtOH-enhanced TNF-alpha production by monocytes. This study also provides insight into the mechanisms of alteration of TNF-alpha production in different EtOH exposure settings.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Carcinogens
  • Cell Line
  • Central Nervous System Depressants / pharmacology*
  • Dose-Response Relationship, Drug
  • Ethanol / pharmacology*
  • Humans
  • Lipopolysaccharides
  • Monocytes / drug effects*
  • Monocytes / metabolism
  • Reactive Oxygen Species / metabolism
  • Tetradecanoylphorbol Acetate
  • Tumor Necrosis Factor-alpha / drug effects*
  • Tumor Necrosis Factor-alpha / metabolism


  • Carcinogens
  • Central Nervous System Depressants
  • Lipopolysaccharides
  • Reactive Oxygen Species
  • Tumor Necrosis Factor-alpha
  • Ethanol
  • Tetradecanoylphorbol Acetate