Liv.52 regulates ethanol induced PPARγ and TNF α expression in HepG2 cells

Liver is a prime target of alcohol-induced damage by inducing inflammatory cytokines especially tumor necrosis factor alpha (TNF alpha). Activator of peroxisome proliferator activator receptor gamma (PPAR gamma) is protective against alcohol-induced liver injury in animals. Liv.52, one of the major herbal hepatoprotective drugs, is shown to protect the liver from toxicity and is considered to be an effective hepatoprotective agent. However, the signal pathway involved in the Liv.52-induced hepatoprotection is not understood well especially in the case of cultured liver cells treated with ethanol. Hence, the study was aimed at determining whether ethanol and Liv.52 could modulate PPAR gamma and TNF alpha induction in human hepatoma cells, HepG2. The present study with RT-PCR and confocal microscopy experiments showed that ethanol (100 mM) induced suppression of PPAR gamma expression in HepG2 cells. The ethanol-induced PPAR gamma suppression was abrogated by Liv.52. Moreover, Liv.52 also induced upregulation of PPAR gamma mRNA in liver cells as compared to the untreated cells. Further, 100 mM ethanol has also induced TNF alpha gene expression in HepG2 cells and interestingly Liv.52 abolished ethanol-induced TNF alpha. The study also shows that Liv.52 alone downregulated TNF alpha expression in HepG2 cells. Taken together, these findings suggest that Liv.52 is capable of attenuating ethanol-induced expression of TNF alpha and abrogating ethanol-induced suppression of PPAR gamma in liver cells. These results indicate that Liv.52-induced PPAR gamma expression and concomitant suppression of ethanol-induced elevation of TNF alpha in HepG2 cells suggest the immunomodulatory and hepatoprotective nature of Liv.52.