Ketone ester alleviates sepsis-associated liver injury through β-hydroxybutyrylation of STAT1.

Sepsis-associated liver injury is characterized by excessive inflammation and macrophage activation. β-Hydroxybutyrate (β-OHB) has anti-inflammatory effects and induces lysine β-hydroxybutyrylation (Kbhb), but the role of site-specific Kbhb in septic liver injury remains unclear. This study examined the role of STAT1 K679 Kbhb in the protective effect of ketone ester (KE) against LPS-induced liver injury. STAT1p.K679R knock-in mice were generated, and liver injury was induced by lipopolysaccharide (LPS). KE pretreatment alleviated hepatic histopathological injury, reduced serum alanine aminotransferase and aspartate aminotransferase levels, and decreased the Bax/Bcl-2 ratio in wild-type mice. These effects were significantly attenuated in STAT1p.K679R mice. KE increased hepatic STAT1 Kbhb, whereas the K679R mutation markedly reduced this modification. In RAW264.7 macrophages, K679R reduced β-OHB-induced STAT1 Kbhb, while no significant effect was observed in AML12 hepatocytes. KE also reduced hepatic M1 macrophage markers, IL-6 and IL-12 expression, and STAT1 Ser727 phosphorylation in LPS-treated wild-type mice, whereas these effects were attenuated by K679R. These results show that STAT1 K679 Kbhb contributes to the inhibition of macrophage M1 polarization by KE and is involved in its protective effect against LPS-induced liver injury.