Ghrelin attenuates plasminogen activator inhibitor-1 production induced by tumor necrosis factor-alpha in HepG2 cells via NF-kappaB pathway

Plasminogen activator inhibitor type 1 (PAI-1), produced partly from liver is a risk factor for macrovascular and microvascular complications of diabetes. Ghrelin, a recently described orexigenic peptide hormone, attenuates PAI-1 induced by TNF-alpha in the human hepatoma cell line (HepG2). Exposure to TNF-alpha (1 ng/ml) for 24h caused a significant increase in PAI-1 mRNA expression and protein secretion, as evaluated by RT-PCR and ELISA, but pretreatment with ghrelin (1-100 ng/ml) inhibited both basal and TNF-alpha-induced PAI-1 release in a dose and time-dependent manner in HepG2. PDTC, selective NF-kappaB inhibitor, had no additive inhibitory effects with ghrelin. The results indicate that ghrelin inhibits both basal and TNF-alpha-induced PAI-1 production via NF-kappaB pathway in HepG2 cells, and suggest that the peptide plays a therapeutic role in atherosclerosis, especially in obese patients with insulin resistance, in whom ghrelin levels were reduced.