Role of cytokines in ethanol-induced cytotoxicity in vitro in Hep G2 cells

Gastroenterology. 1998 Jul;115(1):157-66. doi: 10.1016/s0016-5085(98)70377-4.

Abstract

Background & aims: As shown previously by us, ethanol (EtOH) causes time- and concentration-dependent reduction in cytoviability. Tauroursodeoxycholic acid (TUDCA) and ursodeoxycholic acid (UDCA) were shown to reduce cytotoxicity. Long-term EtOH exposure leads to immunoregulatory and detoxification impairment. This study aimed to determine the relationship between cytokine (interleukin [IL]-1 alpha and IL-6 and tumor necrosis factor [TNF]-alpha) production and expression, glutathione (GSH) status, and EtOH-induced cytotoxicity on Hep G2 cells.

Methods: Cells were incubated with 80 mmol/L EtOH or alpha-minimal essential medium (control) in the presence or absence of 50 mumol/L TUDCA or UDCA. Cytokine release was quantitated by enzyme-linked immunosorbent assay. Cytokine expression was measured by reverse-transcription polymerase chain reaction. GSH content was determined in both the cytosolic and mitochondrial fractions.

Results: After 24 hours of EtOH exposure, the release of IL-1 alpha doubled, that of IL-6 increased 10 times, and that of TNF-alpha increased 3.5 times. Cytokine expression was up-regulated compared with control for IL-1 alpha (42%), IL-6 (26%), and TNF-alpha (52%). Addition of 50 mumol/L TUDCA or UDCA reduced cytokine release and expression. TNF-alpha increased cytotoxicity by 18%. Anti-TNF-alpha antibody almost abolished it. EtOH depleted mGSH levels by 55% (P < 0.001). TUDCA replenished them by 88%.

Conclusions: EtOH up-regulated expression of cytokines in Hep G2 cells is down-regulated by bile acids. Increased amounts of TNF-alpha and depletion in both cytosolic and mitochondrial GSH contribute to EtOH cytotoxicity. Bile acids prevent toxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Cell Survival / drug effects
  • Cytokines / physiology*
  • Ethanol / metabolism
  • Ethanol / toxicity*
  • Glutathione / analysis
  • Humans
  • Liver Neoplasms / pathology
  • Tumor Cells, Cultured
  • Tumor Necrosis Factor-alpha / physiology

Substances

  • Cytokines
  • Tumor Necrosis Factor-alpha
  • Ethanol
  • Glutathione