Abstract 13859: The Omics Signature of Human Pericardial Fluid Exosomes Reveals the Therapeutic Potential of APAF-1 Inhibition in Ischemic Heart Disease

Abstract

Background: The human pericardial fluid (PF) contains heart-derived small extracellular vesicles (sEVs) able to induce vascular responses via microRNA (miR) transfer. People with diabetes (DM) are particularly at risk of severe ischemic heart disease (IHD) and might require personalized therapeutic treatment. Hypothesis: The PF-sEVs molecular profiling supports the identification of clinical-relevant therapeutic targets. Aims: 1) To characterize PF-sEVs of IHD patients with/out type-2 DM (T2DM) in comparison to controls; 2) to validate the emerging therapeutic target candidates. Methods: PF samples (n=12/group) were collected during cardiac surgeries, namely CABG (for IHD with/out DM groups) and mitral valve repair (non-IHD, non-DM control group). sEVs were prepared (SEC), quality controlled (Nanosight and Exoview) and submitted to untargeted proteomics and microRNA array (Exiqon) or validation experiments. miRNA-target prediction methods and integration of proteomics and transcriptomics via networks identified differentially expressed pathogenic proteins and their putative endogenous miRNA regulators. The emerging dysregulated miRNA/protein axis was investigated in vitro and in mice with myocardial infarction (MI) and with/out diet-induced T2DM. Results: the PF-EVs of IHD patients with DM showed increased APAF-1 and reduced let-7b-5p, a miR which we have demonstrated to repress APAF-1 by direct 3’-UTR-binding. Exposure of endothelial cells (ECs) to DM and IHD-mimicking culture conditions increases APAF-1 level, triggering apoptosis and reducing angiogenesis. The phenotype of ECs kept under disease-mimicking conditions was rescued by APAF-1 silencing (siRNAs) and by supplementation with either healthy PF-EV or LNPs carrying let-7b-5p as sole miR cargo. The synthetic APAF-1 inhibitor ZYZ-488 improved post-MI cardiac function (Vevo3100 echocardiography), increased capillary density and reduced EC apoptosis in the peri-infarct area of diabetic and non-diabetic mice of both sexes. Conclusions: PF-EVs represent a novel and privileged source for the discovery of clinical-relevant therapeutic targets. APAF-1 inhibition holds value for post-ischemic cardiac protection and repair, including in diabetic people.