ROLE OF CYTOKINES IN ETHANOL-INDUCED CYTOTOXICITY IN-VITRO IN HEP G2 CELLS

Background & Aims: As shown previously by us, ethanol (EtOH) causes ti me- and concentration-dependent reduction in cytoviability, Tauroursod eoxycholic 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 rela tionship 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: C ells were incubated with 80 mmol/L EtOH or alpha-minimal essential med ium (control) in the presence or absence of 50 mu mol/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 ROH exposure, the release of IL-1 alpha doubled, that of IL-6 increased 10 times, and th at of TNF-alpha increased 3.5 times. Cytokine expression was upregulat ed compared with control for IL-1 alpha (42%), IL-6 (26%), and TNF-alp ha (52%), Addition of 50 mu mol/L TUDCA or UDCA reduced cytokine relea se and expression. TNF-alpha increased cytotoxicity by 18%. Anti-TNF-a lpha antibody almost abolished it. EtOH depleted mGSH levels by 55% (P < 0.001). TUDCA replenished them by 88%, Conclusions: EtOH up-regulat ed expression of cytokines in Hep G2 cells is down-regulated by bile a cids. Increased amounts of TNF-alpha and depletion in both cytosolic a nd mitochondrial GSH contribute to ROH cytotoxicity. Bile acids preven t toxicity.