AIM  To explore the ability and mechanism of β-hydroxybutyrate (β-OHB) in inhibiting pyroptosis of cardiomyocytes and attenuating ischemia-reperfusion (I/R) injury.

  METHODS  H9c2 cells were treated with β-hydroxybutyrate and then treated with hypoxia/reoxygenation (H/R) to detect the influence of β-hydroxybutyrate on cell viability and the expression of molecules associated with pyroptosis. After H9c2 cells were transfected with FoxO3 siRNA by lipo2000, treated with β-hydroxybutyrate and subjected to H/R injury, the cell survival, LDH release and expression of pyroptosis-related molecules were analyzed. Twenty-four 5-week-old healthy male C57BL/6 mice were randomly divided into a control group and a β-hydroxybutyrate treatment group (12 mice in each) and each group was then randomly subdivided into sham group and acute myocardial ischemia reperfusion (MI/R) group (6 mice in each). In β-hydroxybutyrate treatment group, an osmotic pump was implanted subcutaneously 5min before the operation, so that the mice were continuously subjected to β-hydroxybutyrate 1 μl/h, 1.6 mmol/(kg·d) during the operation. In control group, the implanted osmotic pump contains only phosphate buffer.

  RESULTS  Different concentrations of β-hydroxybutyrate had different protective effects on H9c2 cells with H/R injury. The cell viability increased with the concentration gradient when the concentration was less than 10mM, while the protective effect of β-hydroxybutyrate on H9c2 cells reduced at concentrations greater than 10 mM. Under the treatment of β-hydroxybutyrate, both the histone acetylation level and the expression of FoxO3 increased in cardiomyocytes, but the expression of pyroptosis-related molecules (Caspase-1, IL-1β, IL-18 and GSDMD) decreased. After the interference of FoxO3 by siRNA, the inhibition of β-hydroxybutyrate on the expression of pyroptosis-related molecules was reduced in H9c2 cells after H/R injury. In the MI/R mice model, β-hydroxybutyrate promoted the acetylation of histones in the myocardial tissue, increased the expression of FoxO3 and reduced the expression of pyroptosis-related molecules, thus attenuating the MI/R injury.

  CONCLUSION  β-hydroxybutyrate promotes the acetylation of histones and enhances the expression of FoxO3 in cardiomyocytes, which inhibits Caspase-1-mediated pyroptosis and attenuates MI/R injury.