Project description:Background: Coronary microvascular disease (CMD) is an early complication of type 2 diabetes (T2D) involving adverse endothelial and smooth muscle dysfunction, vascular remodeling, and alterations in mechanics, which culminate in impaired coronary blood flow. Recent data suggest that vascular layer-specific mechanisms, influenced by the surrounding myocardium, contribute to CMD. To investigate transcriptional differences potentially contributing to CMD, we used spatial and single cell transcriptomic profiling of the coronary microcirculation and surrounding myocardium across distinct heart subregions to identify new pathways to target. Methods: We combined single cell RNA profiling and spatial transcriptomics to examine transcriptional differences and molecular signatures of CMD in T2D mice. Results: Single cell RNA profiling and spatial transcriptomics revealed upregulation of genes linked to adipogenesis, fatty acid metabolism, and oxidative phosphorylation in T2D cell clusters and coronary microvascular-enriched regions. Using spatial transcriptomics, we also examined gene expression in coronary microvessel-enriched areas across different heart subregions. Interestingly, the most pronounced transcriptional differences between T2D and control coronary microvessels were observed in the left ventricular anterior wall, where inflammatory response pathways were downregulated in T2D mice. Genes associated with oxidative phosphorylation and fatty acid oxidation were significantly upregulated in T2D coronary microvessels within the left ventricular anterior wall.Conclusions: These intriguing data support the well-documented concept that cardiac metabolic inflexibility in T2D – characterized by reduced mitochondrial function, increased reliance on fatty acid oxidation, and impaired glucose utilization – contributes to oxidative stress and lipotoxicity, key drivers of heart failure. Furthermore, these data reveal previously unrecognized transcriptomic differences in coronary microvessels across spatially-distinct regions of the T2D heart, suggesting transcriptional heterogeneity in this critical vascular bed.

Project description:Background Sunitinib is a small molecule tyrosine kinase inhibitor approved for the treatment of diverse cancers. Despite widespread clinical approval the associated cardiovascular toxicity sequelae are of concern; high grade toxicities may lead to dose reduction, interruption or discontinuation. Thus, an effective strategy for the early detection of cardiac damage in the context of sunitinib treatment is warranted. Although yet to be fully elucidated, molecular pathways and kinases implicate include those related to cardiac energy metabolism. We hypothesised that plasticity in cardiac metabolism could represent a novel early marker of cardiotoxicity. Methods and Results Female Balb/CJ mice (n = 36) or Sprague-Dawley rat (n = 12) models were treated with sunitinib. Physiological parameters were measured. An hypothesis driven cardiac positron emission tomography (PET) approach was implemented to investigate alterations in myocardial glucose, fatty acid and oxidative metabolism. Following treatment, blood pressure increased, whilst left ventricular ejection fraction decreased in both models. Increased myocardial glucose uptake after 48 hours indicated early perturbations in glucose metabolism. Myocardial fatty acid metabolism appeared increased as a result of sunitinib treatment indicated by PET but electron microscopy revealed significantly increased storage of lipids in the myocardium. Proteomic analyses indicated that oxidative metabolism, fatty acid β-oxidation and mitochondrial dysfunction were among the top cardiac signalling pathways perturbed by sunitinib treatment. [11C]Acetate-PET data suggested a decrease in myocardial perfusion following 5 days of treatment. Conclusions Data implicates sunitinib as a mediator of compromised myocardial energy metabolism. Increased reliance on glycolysis, increases in myocardial lipid deposition and perturbed mitochondrial function may ultimately result in a fundamental energy crisis manifesting as compromised cardiac function, the long term effects of which are unknown. Our data support the utility of an hypothesis driven PET approach to monitor cardiac metabolic pathway remodelling in response to sunitinib, which may ultimately have clinical utility as a novel safety imaging biomarker strategy.

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Transcriptomic profiling of Guanxin Shuxin powder effects on a mouse model of coronary microvascular dysfunction

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