Abstract 10526: Surface Located Adiponectin On Adipocytes-derived Exosomes Mediates Adipocytes/cardiomyocytes Communication And Contributes To Cardioprotection

Abstract

Introduction and Hypothesis: Increasing evidence emphasizes the roles of adipocyte-cardiomyocyte (ADp-CM) communication plays in health and diabetes. We recently reported that diabetes switched ADp-derived Exosomes (ADp-Exo) from carrying cardioprotective molecules to delivering cardiotoxic molecules to CM. However, the molecular mechanisms mediating ADp-Exo cardioprotection and its alteration by diabetes remain unknown. Methods and Results: ADp-Exo was isolated from epididymal white adipocytes of WT mice. Western Blot demonstrated high level of adiponectin (APN), a potent cardioprotective adipokine, present in ADp-Exo. More interestingly, APN was detected on the surface of ADp-Exo by flow cytometry using Exo-flow kit (System Biosciences). To determine whether surface-located APN on ADp-Exo protect heart, WT ADp-Exo were intramyocardially injected. Mice were subjected to 90 minutes coronary occlusion, followed by 4 weeks of reperfusion. Cardiac function was evaluated by echocardiograph weekly. WT ADp-Exo significantly reduced MI/R injury in vivo , as evidenced by improved LVEF, radial and longitudinal myocardial Strain and SR (vs vehicle group, p<0.05). Importantly, pre-incubation of ADp-Exo with an APN neutralization antibody blocked ADp-Exo cardioprotection. To determine the role of CM AdipoR1, ex vivo and in vitro experiments were performed. WT ADp-Exo activated AdipoR1 pathway (increased phosphorylation of ACC, ERK and AMPK) in CM and protected against cell injury and death (MTT and LDH assay). However, surface APN blocked WT ADp-Exo or APN -/- ADp-Exo failed to active this signaling and protection. WT ADp-Exo failed to activate cell salvage kinases in AdipoR1 -/- CM. Finally, overexpression of GRK2, a pathogenic molecule that we reported to cause AdipoR1 S205 phosphorylation, blocked WT ADp-Exo cardioprotection. AAV9-mediated overexpression of a phosphorylation resistant AdipoR1 (AdipoR1 S205A ) restored ADp-Exo protective action. Conclusions: We demonstrate for the first time that ADp-Exo surface located APN mediates ADp-CM communication via CM AdipoR1 pathway, promoting cardioprotection. This protective system is blocked by GRK2-induced AdipoR1 phosphorylation in diabetic heart, promoting MI/R injury.