Background Hepatic stellate cell (HSC) activation is a central event during hepatic fibrosis. Aerobic glycolysis is one of its metabolic hallmarks. Blocking glycolysis is a novel therapeutic option for liver fibrosis. This study investigated the effects of costunolide, a natural product demonstrated to have hepatoprotective effects, on HSC activation and glycolysis. Methods Primary HSCs were isolated from rats and cultured through 5 to 6 passages. Cell viability, activation markers, and glycolytic metabolism were examined in primary HSCs using various cellular and molecular approaches. Results At 30 μM, costunolide reduced the viability of HSCs and inhibited the expression of α-smooth muscle actin and collagen I, two key markers of HSC activation. It also decreased glucose uptake and consumption, and reduced the intracellular levels of lactate in HSCs. At 10 mM, the glycolysis inhibitor 2-DG had a similar impact to costunolide at 30 μM: it significantly downregulated the expression of HSC activation markers. The combination of the two compounds produced more remarkable effects. Furthermore, costunolide repressed the expression and activity of hexokinase 2 (HK2), a pivotal rate-limiting enzyme that regulates glycolysis. However, overexpression of HK2 via plasmid transfection significantly reversed the costunolide-mediated downregulation of activation markers in HSCs, indicating that suppression of HK2 was required for costunolide to inhibit glycolysis-associated HSC activation. Conclusions Our results show that costunolide can suppress HSC activation, and this is associated with inhibition of HK2, which blocks aerobic glycolysis. This suggests that costunolide is an antifibrotic candidate with potential for further development.

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