Abstract Body: Background: Oxidative stress is an established driver of heart failure, but the temporal and metabolic mechanisms underlying the transition from diastolic to systolic dysfunction remain poorly defined. We used chemogenetic approaches to dynamically modulate cardiac redox status with high-precision control to understand this clinical inflection point and reveal new therapeutic opportunities.
Objective: We tested the hypothesis that chronic, cardiomyocyte–specific oxidative stress induces an early energetic defect that precipitates diastolic dysfunction and leads to systolic failure.
Methods: Transgenic mice expressing a cardiomyocyte–specific D amino acid oxidase construct (DAAO-TG^Car) enabled tunable hydrogen peroxide (H₂O₂) generation upon D–alanine exposure. Wild–type littermates receiving D–alanine served as controls. Cardiac function was assessed by echocardiography (n=7–14/group) and pressure–volume analysis (n=5–6/group) at 2 and 4 weeks. Metabolomics and proteomics were performed (n=5–6/group).
Results: At 2 weeks, D–alanine-treated DAAO-TG^Car mice developed marked diastolic dysfunction with elevated E/A ratio (1.35±0.04 vs 4.23±1, p<0.0001), increased left atrial area (4.4±0.2 vs 9.4±0.6 mm², p<0.0001) and prolonged relaxation time constant Tau (8.4±0.5 vs 10.8±0.6 ms, p<0.05), despite preserved ejection fraction (60±2 vs 55±2 %, p=NS) and no fibrosis. By 4 weeks, the animals developed systolic dysfunction, with reduced ejection fraction (62±2 vs 36±3 %, p<0.001), ventricular dilation (ESV: 18.9±1.7 vs 35.8±3.4 µL, p<0.01), and fibrosis. Multi-omics revealed early energetic collapse at 2 weeks, characterized by reduced mitochondrial mass (decreased mtDNA/nDNA ratios and mitochondrial protein content), suppressed fatty acid oxidation, accumulation of long-chain acylcarnitines, and impaired mitophagy. These defects intensified at 4 weeks, coinciding with structural remodeling and systolic dysfunction.
Conclusion: Chronic cardiomyocyte oxidative stress induces an early bioenergetic crisis, marked by mitochondrial loss and impaired metabolic capacity that drives diastolic dysfunction, ultimately leading to systolic heart failure. These findings identify a discrete metabolic window for therapeutic intervention before irreversible structural remodeling occurs.