Shikonin Attenuates Liver Ischemia-Reperfusion Injury Through Direct Interaction With HMGB1 Protein

Hepatic ischemia-reperfusion (IR) injury represents a critical clinical challenge characterized by excessive inflammation. HMGB1, known as a proinflammatory mediator released after liver IR injury, has been reported to worsen the damage and inflammation via a positive feedback loop. Herein, shikonin has been explored to alleviate hepatic IR injury through direct interaction with HMGB1.

The ligation on the hilum of the right liver lobe lasted for 90 min and then removed to induce hepatic IR injury in SD rats. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were determined. At the cellular level, HMGB1-induced NO release from RAW264.7 was assessed to test the inhibitory effect of shikonin. The surface plasmon resonance (SPR), saturation transfer difference nuclear magnetic resonance (STD-NMR), and molecular dynamics simulation were employed to study the interaction between shikonin and HMGB1.

After administration of shikonin, the degree of liver IR damage in rats was attenuated significantly in a dose-dependent manner. In vitro, shikonin can effectively inhibit HMGB1 activation. Furthermore, mechanistic studies indicated that shikonin could directly bind to HMGB1. The results of ¹H STD-NMR confirmed that shikonin interacted with HMGB1, and multiple protons in shikonin participated in the binding process. Notably, shikonin exhibits a selective binding affinity toward the I122 and L129-bearing region of HMGB1, which were supported by molecular dynamics simulation.

In general, our results suggest that shikonin is a promising natural candidate that directly targets HMGB1 to exert hepatoprotection for the development of clinical therapeutic anti-IR agents.