β-Hydroxybutyrate inhibits histone deacetylase 3 to promote claudin-5 generation and attenuate cardiac microvascular hyperpermeability in diabetes

Aims/hypothesis Microvascular endothelial hyperpermeability, mainly caused by claudin-5 deficiency, is the initial pathological change that occurs in diabetes-associated cardiovascular disease. The ketone body beta-hydroxybutyrate (BHB) exerts unique beneficial effects on the cardiovascular system, but the involvement of BHB in promoting the generation of claudin-5 to attenuate cardiac microvascular hyperpermeability in diabetes is poorly understood. Methods The effects of BHB on cardiac microvascular endothelial hyperpermeability and claudin-5 generation were evaluated in rats with streptozotocin-induced diabetes and in high glucose (HG)-stimulated human cardiac microvascular endothelial cells (HCMECs). To explore the underlying mechanisms, we also measured beta-catenin nuclear translocation, binding of beta-catenin, histone deacetylase (HDAC)1, HDAC3 and p300 to the Claudin-5 (also known as CLDN5) promoter, interaction between HDAC3 and beta-catenin, and histone acetylation in the Claudin-5 promoter. Results We found that 10 weeks of BHB treatment promoted claudin-5 generation and antagonised cardiac microvascular endothelial hyperpermeability in rat models of diabetes. Meanwhile, BHB promoted claudin-5 generation and inhibited paracellular permeability in HG-stimulated HCMECs. Specifically, BHB (2 mmol/l) inhibited HG-induced HDAC3 from binding to the Claudin-5 promoter, although nuclear translocation or promoter binding of beta-catenin did not change with BHB treatment. In addition, BHB prevented the binding and co-localisation of HDAC3 to beta-catenin in HG-stimulated HCMECs. Furthermore, using mass spectrometry, acetylated H3K14 (H3K14ac) in the Claudin-5 promoter following BHB treatment was identified, regardless of whether cells were stimulated by HG or not. Although reduced levels of acetylated H3K9 in the Claudin-5 promoter were found following HG stimulation, increased H3K14ac was specifically associated with BHB treatment. Conclusions/interpretation BHB inhibited HDAC3 and caused acetylation of H3K14 in the Claudin-5 promoter, thereby promoting claudin-5 generation and antagonising diabetes-associated cardiac microvascular hyperpermeability.

Automated summary

This study demonstrates that BHB can promote claudin-5 generation and inhibit cardiac microvascular endothelial hyperpermeability in diabetic rats and human cardiac microvascular endothelial cells. The mechanism involves BHB inhibiting HDAC3 and causing histone H3K14 acetylation in the Claudin-5 promoter.