Leptin downregulates ethanol-induced secretion of proinflammatory cytokines and growth factor

Inflammatory mediators, including cytokines and growth factors are associated with the pathology of chronic liver diseases. The aim of our present work was to study the effect of exogenous leptin and/or ethanol on the secretion of TNF-α, IL-6 and TGF-β1 both in vivo and in vitro. Forty eight hours after the exposure to ethanol (500 mM) significantly elevated the secretion of TNF-α, IL-6 and TGF-β1 in the cell-free culture supernatant (HepG2 and mouse HCC cell lines), which were decreased on leptin (31.2 nM) treatment. Similarly, leptin administration to ethanol (6.32 g kg^-1 body weight) fed mice for 45 days significantly lowered the concentration of these cytokines in the circulation; however, leptin alone (230 μg kg^-1 body weight i.p. administered every alternate day for the last 15 days) had no such significant effect on cytokine secretion both in vivo and in vitro conditions. We conclude that leptin is involved in the protective mechanisms that allow an organism to cope with the potentially autoaggressive effects of its immune system in alcoholic liver disease.