Impaired myocardial efficiency in cardiovascular-kidney-metabolic syndrome swine: role of branched-chain amino acids

Abstract Background Exercising swine with cardiovascular-kidney-metabolic syndrome show increased myocardial oxygen consumption despite comparable cardiac work, suggesting reduced myocardial energetic efficiency. We hypothesized that this excess oxygen consumption results from impairments in myocardial metabolism. To test our hypothesis and to investigate the molecular mechanisms causing disrupted metabolism we applied a comprehensive multi-omic approach in female swine with 6 months of cardiovascular-kidney-metabolic syndrome (CKM). Methods and Results Swine were assigned to either healthy controls (n=10) or CKM (n=15). CKM swine were exposed to combined metabolic stress (hypercholesterolemia by high-fat, high glucose and high salt diet and hyperglycaemia by streptozotocin), and chronic kidney disease (renal microembolization). Proteomic analysis revealed increased abundance of cellular-metabolism proteins in CKM swine myocardium (Figure 1A). Single-nucleus RNA sequencing confirmed that these changes were localized to cardiomyocytes (Figure 1B) and showed that branched-chain amino acid (BCAA) metabolism-related proteins were most downregulated in CKM cardiomyocytes (Figure 1C). Consistent with impaired BCAA degradation, myocardial BCAA levels were elevated (16.4 ± 1.2 vs. 10.8 ± 1.0 µM/mg protein, CKM vs. control, P0.05). In targeted mechanistic studies using cultured HL-1 cardiomyocytes, 48h BCAA exposure reduced maximal uncoupled respiration (02 flux, 81 ± 6 (BCAA) vs. 115 ± 9 pmol·s⁻¹·(10⁶ cells)⁻¹ (Vehicle control), P0.01) and increased leak respiration (02 flux, 14 ± 1 (BCAA) vs. 11 ± 1 pmol·s⁻¹·(10⁶ cells)⁻1 (Vehicle control), P0.01)(Figure 2A). In ex vivo living myocardial slice preparations, BCAA exposure resulted in reduced contractile performance, controls changed from baseline 1722 ± 359 to 48h vehicle 1388 ± 331 µN; with BCAA, baseline 1659 ± 256 declines to 763 ± 134 µN upon 48h BCAA stimulation, P0.05)(Figure 2B). Conclusion Using a translational large-animal model of cardiovascular-kidney-metabolic syndrome, and an unbiased multi-omic approach, we identified a consistent signature of dysregulated branched-chain amino acid metabolism in the myocardium. Ex-vivo, increased BCAA levels impaired mitochondrial respiration, and reduced contractile performance, highlighting a metabolic contribution to early cardiac dysfunction.Figure 1For image description, please refer to the figure legend and surrounding text. Figure 2For image description, please refer to the figure legend and surrounding text.