Downregulation of HDAC9 by the ketone metabolite β‐hydroxybutyrate suppresses vascular calcification

Abstract Vascular calcification is an actively regulated process resembling bone formation and contributes to the cardiovascular morbidity and mortality of chronic kidney disease (CKD). However, an effective therapy for vascular calcification is still lacking. The ketone body β‐hydroxybutyrate (BHB) has been demonstrated to have health‐promoting effects including anti‐inflammation and cardiovascular protective effects. However, whether BHB protects against vascular calcification in CKD remains unclear. In this study, Alizarin Red staining and calcium content assay showed that BHB reduced calcification of vascular smooth muscle cells (VSMCs) and arterial rings. Of note, compared with CKD patients without thoracic calcification, serum BHB levels were lower in CKD patients with thoracic calcification. Supplementation with 1,3‐butanediol (1,3‐B), the precursor of BHB, attenuated aortic calcification in CKD rats and VitD3‐overloaded mice. Furthermore, RNA‐seq analysis revealed that BHB downregulated HDAC9, which was further confirmed by RT‐qPCR and western blot analysis. Both pharmacological inhibition and knockdown of HDAC9 attenuated calcification of human VSMCs, while overexpression of HDAC9 exacerbated calcification of VSMCs and aortic rings, indicating that HDAC9 promotes vascular calcification under CKD conditions. Of note, BHB treatment antagonized HDAC9‐induced vascular calcification. In addition, HDAC9 overexpression activated the NF‐κB signaling pathway and inhibition of NF‐κB attenuated HDAC9‐induced VSMC calcification, suggesting that HDAC9 promotes vascular calcification via activation of NF‐κB. In conclusion, our study demonstrates that BHB supplementation inhibits vascular calcification in CKD via modulation of the HDAC9‐dependent NF‐κB signaling pathway. Moreover, we unveil a crucial mechanistic role of HDAC9 in vascular calcification under CKD conditions; thus, nutritional intervention or pharmacological approaches to enhance BHB levels could act as promising therapeutic strategies to target HDAC9 for the treatment of vascular calcification in CKD. © 2022 The Pathological Society of Great Britain and Ireland.