BET protein inhibition rewires the vascular-fat interface in cardiometabolic disease

Abstract Background/Introduction Epigenetic reading of histone marks by BET proteins is emerging as a pivotal mechanism governing gene transcription and could be implicated in cardiometabolic disease. The epigenetic reader BRD4 has shown a prominent role in the regulation of inflammatory transcriptional programs. Whether BET proteins participate in endothelial and perivascular adipose tissue (PVAT) dysfunction remains elusive. Purpose To investigate the role of BET proteins in cardiometabolic disease. Methods To mirror cardiometabolic disease, we adopted two models characterized by the combination of metabolic and hemodynamic stress: i) patients with obesity and hypertension and ii) mice administered high-fat diet and L-name supplementation. In humans, we assessed the impact of ex-vivo BRD4 inhibition on vascular function by RVX-208 (an FDA-approved BRD4 inhibitor) in small vessels (100-300 μM) dissected from omental fat biopsies. In mice, we evaluated chronic BRD4 inhibition by a 14-day oral administration of RVX-208. Vascular function was evaluated in the presence and in the absence of perivascular adipose tissue (PVAT). The effect of BRD4 inhibition was compared to anti-inflammatory drugs. We corroborated our functional data with molecular characterisation of the pathways involved, leveraging transcriptional screening, proteomics, metabolomics and lipidomics analyses. Finally, an in vitro cross-talk model employing human perivascular adipocytes and endothelial cells was used. Finally, ex vivo functional experiments were employed to confirm our molecular findings by gain and loss-of-function approaches. Results In vessels from mice and patients with cardiometabolic disease, we show that pharmacological editing of BET proteins by RVX-208 prevents a maladaptive cross-talk between PVAT and blood vessels. This epi-drug exerted a potent anti-inflammatory action and a marked effect on endothelial function as compared to well-established anti-inflammatory drugs, namely IL-1β, IL-6 or TNF-α inhibitors. The effects of BET inhibition on endothelial function were more pronounced in the presence of PVAT, suggesting a pivotal role of this organ (Figure 1). In mouse and human PVAT, RVX-208 rescued maladaptive transcriptional programs, with a marked downregulation of hexokinase-2 (HK-2), a gene predominantly expressed in adipocytes. HK-2 overexpression in human PVAT adipocytes led to glycolytic overload, lipid accumulation and secretome changes eventually promoting endothelial damage. Of clinical relevance, pharmacological inhibition of HK-2 in vessels from cardiometabolic patients restored endothelial dysfunction (Figure 2). Conclusions Inhibition of BRD4 downregulates HK2 while reversing pro-glycolytic changes and triglyceride accumulation in PVAT, thus rescuing vascular dysfunction. The unveiling of a BET-dependent cross-talk between PVAT and blood vessels supports therapeutic strategies to prevent vascular disease in cardiometabolic patients.