The BET inhibitor Apabetalone protects against heart failure with preserved ejection fraction by suppressing myocardial inflammation

• Published in: European heart journal Vol. 45; no. Supplement_1
• Main Authors: Costantino, S, Gorica, E, Mohammed, S A, Telesca, M, Mongelli, A, Herwig, M, Ambrosini, S, Ruschitzka, F, Hamdani, N, Paneni, F
• Format: Journal Article
• Language: English
• Published: 28.10.2024
• ISSN: 0195-668X; 1522-9645
• DOI: 10.1093/eurheartj/ehae666.3756

Abstract Background Posttranslational histone modifications, play a major role in cardiac hypertrophy and dysfunction. Apabetalone (APA), a selective inhibitor of bromodomain and extraterminal containing protein family (BET) proteins, prevents bromodomain-containing protein 4 (BRD4) interactions with chromatin thus modulating transcriptional programs in different organs. Purpose We sought to investigate whether APA could be beneficial in cardiometabolic heart failure with preserved ejection fraction (cHFpEF). Methods Mice were subjected to high fat diet feeding and L-NAME treatment for 15 weeks to induce cHFpEF. Histology, mouse echocardiography (Vevo3100) and Treadmill exhaustion test were performed. Unbiased gene expression profiling by PCR array and proteomics analysis (Olink) was employed in left ventricular (LV) myocardial specimens from HFpEF mice and control animals. Cultured cardiomyocytes (CMs) treated with palmitic acid (PA) were used as an in vitro model of metabolic stress. cHFpEF mice were chronically treated with the BET inhibitor APA (150mg/kg/day) or vehicle (DMSO). In order to translate our findings to the human setting, passive stiffness of skinned CMs collected from cHFpEF patients was assessed before and after APA treatment. Results HFpEF mice displayed LV hypertrophy, diastolic dysfunction, myocardial fibrosis, lung congestion and impaired exercise tolerance as compared to controls. Interestingly, diastolic dysfunction - assessed by E/A ratio and isovolumic relaxation time (IVRT) - and lung congestion were significantly reduced in HFpEF mice treated with APA, while exercise tolerance was improved. Transcriptomic analysis in PA-treated CMs and LV mouse specimens from cHFpEF mice showed a profound deregulation of genes controlling inflammation, namely IL-6, TNF-alpha, and IL-1beta. ChIP assays showed BRD4 occupancy on the promoter of several inflammatory genes, including IL6. Treatment with APA suppressed most of inflammatory genes, with a pronounced effect on IL6 expression. Moreover, APA reduced circulating levels of several inflammatory chemokines. The beneficial effects of APA were explained by modulation of IL-6/CaMKII/STAT3 pathway both in cHFpEF hearts and PA-treated CMs. In skinned CMs from cHFpEF patients, both APA and IL6 blockade were able to attenuate passive stiffness. Conclusions Our findings set the stage for preclinical studies and exploratory clinical trials testing APA in patients with cHFpEF.