Mechanism Of Adiponectin-Mediated Prevention Of Cardiometabolic Diseases And Therapeutic Potential

Abstract

Myocardial ischemia-reperfusion (IR) injury remains a major contributor to cardiomyocyte loss and heart failure progression despite advances in revascularization. Adiponectin, a cardioprotective adipokine reduced in cardiovascular disease and obesity, has well-recognized benefits, yet the mechanisms underlying adiponectin receptor–mediated protection during IR injury remain incompletely defined. This thesis investigates the multi-layered cardioprotective actions of ALY688, a synthetic adiponectin receptor agonist, with a focus on extracellular vesicle (EV)-mediated communication, metabolic organellar coupling, and autophagy regulation. Four integrated studies employed complementary in vivo (rat and mouse myocardial infarction models) and in vitro (H9c2 cardiomyocytes and human iPSC-derived cardiomyocytes) approaches. Mechanistic interrogation utilized CRISPR-mediated gene editing, mass spectrometry-based proteomics, lipidomic profiling, real-time autophagy flux assays, and advanced imaging techniques including fluorescence molecular tomography and cryo-electron microscopy. Study 1 demonstrated that ALY688 reduces infarct size and preserves cardiac function through dual mechanisms: direct cardiomyocyte protection, characterized by reduced oxidative stress, restored autophagy flux, and attenuated apoptosis, and Rab8a-dependent EV biogenesis. Genetic ablation of Rab8a abolished EV-mediated cardioprotection, identifying Rab8a as a critical regulator. Study 2 showed that ALY688 reprograms EV cargo toward cardioprotective phenotypes, enriching EVs with adiponectin, metabolic enzymes, and autophagy-related proteins. Systemic delivery of ALY688-derived EVs reduced infarct size, improved cardiac function, and normalized mitochondrial dynamics in both lean and obese mice, supporting the therapeutic potential of EV-based strategies. Study 3 uncovered a previously unrecognized role for Rab8a in maintaining lipid droplet–mitochondria coupling, essential for long-chain fatty acid utilization during ischemic stress. Hypoxia–reoxygenation suppressed Rab8a, disrupting metabolic coupling and promoting lipotoxicity, whereas ALY688 preserved Rab8a via AMPK-dependent signaling, restoring metabolic homeostasis in a Rab8a-dependent manner. Study 4 demonstrated that adiponectin deficiency exacerbates ischemia-induced cardiac dysfunction through impaired autophagy flux. CRISPR-mediated ATG7 deletion confirmed autophagy as mechanistically essential for adiponectin-mediated cytoprotection. This thesis identifies adiponectin receptor signaling as a hierarchically organized cardioprotective network integrating direct cellular signaling, Rab8a-dependent EV biogenesis and cargo remodeling, preservation of lipid droplet-mitochondria metabolic coupling, and context-dependent autophagy regulation. Rab8a emerges as a central hub linking vesicular trafficking with metabolic resilience. These findings support the development of ALY688 and EV-based modalities as multi-mechanistic therapies for acute myocardial infarction and heart failure prevention.