Exosomal microRNAs miR-30d-5p and miR-126a-5p Are Associated with Heart Failure with Preserved Ejection Fraction in STZ-Induced Type 1 Diabetic Rats.

Exosomal microRNAs (EXO-miRNAs) are promising non-invasive diagnostic biomarkers for cardiovascular disease. Heart failure with preserved ejection fraction (HFpEF) is a poorly understood cardiovascular complication of diabetes mellitus (DM). Little is known about whether EXO-miRNAs can be used as biomarkers for HFpEF in DM. We aimed to investigate the relationship between EXO-miRNAs and HFpEF in STZ-induced diabetic rats. We prepared STZ-induced diabetic rats exhibiting a type 1 DM phenotype with low body weight, hyperglycemia, hyperlipidemia and hypoinsulinemia. Histological sections confirmed atrophy and fibrosis of the heart, with collagen accumulation representing diabetic cardiomyopathy. Significant decreases in end-diastolic volume, stroke volume, stroke work, end-systolic elastance and cardiac output indicated impaired cardiac contractility, as well as mRNA conversion of two isoforms of myosin heavy chain (α-MHC and ß-MHC) and increased atrial natriuretic factor (ANF) mRNA indicating heart failure, were consistent with the features of HFpEF. In diabetic HFpEF rats, we examined a selected panel of 12 circulating miRNAs associated with HF (miR-1-3p, miR-21-5p, miR-29a-5p, miR-30d-5p, miR-34a-5p, miR-126a-5p, miR-143-3p, miR-145-5p, miR-195-5p, miR-206-3p, miR-320-3p and miR-378-3p). Although they were all expressed at significantly lower levels in the heart compared to non-diabetic controls, only six miRNAs (miR-21-5p, miR-30d-5p, miR-126a-5p, miR-206-3p, miR-320-3p and miR-378-3p) were also reduced in exosomal content, while one miRNA (miR-34a-5p) was upregulated. Similarly, although all miRNAs were correlated with reduced cardiac output as a measure of cardiovascular performance, only three miRNAs (miR-30d-5p, miR-126a-5p and miR-378-3p) were correlated in exosomal content. We found that miR-30d-5p and miR-126a-5p remained consistently correlated with significant reductions in exosomal expression, cardiac expression and cardiac output. Our findings support their release from the heart and association with diabetic HFpEF. We propose that these two EXO-miRNAs may be important for the development of diagnostic tools for diabetic HFpEF.

Therapeutic potential of cPLA2 inhibitor to counteract dilated-cardiomyopathy in cholesterol-treated H9C2 cardiomyocyte and MUNO rat.

BACKGROUND AND PURPOSE: The pathogenesis of cardiomyopathy in metabolically unhealthy obesity (MUO) has been well studied. However, the pathogenesis of cardiomyopathy typically associated with high cholesterol levels in metabolically unhealthy nonobesity (MUNO) remains unclear. We investigated whether cholesterol-generated LysoPCs contribute to cardiomyopathy and the role of cytosolic phospholipase A2 (cPLA2) inhibitor in cholesterol-induced MUNO. EXPERIMENTAL APPROACH: Cholesterol diet was performed in Sprague-Dawley rats that were fed either regular chow (C), or high cholesterol chow (HC), or HC diet with 10 % fructose in drinking water (HCF) for 12 weeks. LysoPCs levels were subsequently measured in rats and in MUNO human patients. The effects of cholesterol-mediated LysoPCs on cardiac injury, and the action of cPLA2 inhibitor, AACOCF3, were further assessed in H9C2 cardiomyocytes. KEY RESULTS: HC and HCF rats fed cholesterol diets demonstrated a MUNO-phenotype and cholesterol-induced dilated cardiomyopathy (DCM). Upregulated levels of LysoPCs were found in rat myocardium and the plasma in MUNO human patients. Further testing in H9C2 cardiomyocytes revealed that cholesterol-induced atrophy and death of cardiomyocytes was due to mitochondrial dysfunction and conditions favoring DCM (i.e. reduced mRNA expression of ANF, BNP, DSP, and atrogin-1), and that AACOCF3 counteracted the cholesterol-induced DCM phenotype. CONCLUSION AND IMPLICATIONS: Cholesterol-induced MUNO-DCM phenotype was counteracted by cPLA2 inhibitor, which is potentially useful for the treatment of LysoPCs-associated DCM in MUNO.

Resveratrol Mitigates High-Fat Diet-Induced Vascular Dysfunction by Activating the Akt/eNOS/NO and Sirt1/ER Pathway.

We investigated whether resveratrol (RSV) can attenuate obesity and diabetes progression and improve diabetes-induced vascular dysfunction, and we attempted to delineate its underlying mechanisms. Male C57Bl/6 mice were administered a high-fat diet (HFD) for 17 weeks. Mice developed type 2 diabetes with increased body weight, hyperglycemia, hyperinsulinemia, and hyperlipidemia. Oral gavage with RSV significantly reversed the symptoms induced by the HFD. Insulin sensitivity likewise improved after the RSV intervention in these mice. Phenylephrine-induced cremaster arteriolar constriction was impaired, whereas RSV treatment significantly mitigated the vessel responsiveness to phenylephrine. The obese diabetic mice exhibited increased leukocyte rolling, adhesion, and transmigration in the postcapillary venules of the cremaster muscle. By contrast, RSV treatment significantly attenuated HFD-induced extravasation. RSV significantly recovered phosphorylated Akt and eNOS expression in the thoracic aorta. In addition, activated adenosine monophosphate-activated protein kinase in the thoracic aorta was involved in the improvement of epithelial function after RSV intervention. RSV considerably upregulated the plasma NO level in HFD mice. Moreover, RSV-enhanced human umbilical vein endothelial cells healing through Sirt1/ER pathway may be involved in the prevention of leukocyte extravasation. Collectively, RSV attenuates diabetes-induced vascular dysfunction by activating Akt/eNOS/NO and Sirt1/ER pathway. Our mechanistic study provides a potential RSV-based therapeutic strategy against cardiovascular disease.