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Background: Diabetes mellitus exacerbates myocardial ischemia/reperfusion (MI/R) injury by incompletely understood mechanisms. Adipocyte dysfunction contributes to remote organ injury. However, the molecular mechanisms linking dysfunctional adipocytes to increased MI/R injury remain unidentified. The current study attempted to clarify whether and how small extracellular vesicles (sEV) may mediate pathological communication between diabetic adipocytes and cardiomyocytes, exacerbating MI/R injury.Methods: Adult male mice were fed a normal or a high-fat diet for 12 weeks. sEV (from diabetic serum, diabetic adipocytes, or high glucose/high lipid-challenged nondiabetic adipocytes) were injected intramyocardially distal of coronary ligation. Animals were subjected to MI/R 48 hours after injection.Results: Intramyocardial injection of diabetic serum sEV in the nondiabetic heart significantly exacerbated MI/R injury, as evidenced by poorer cardiac function recovery, larger infarct size, and greater cardiomyocyte apoptosis. Similarly, intramyocardial or systemic administration of diabetic adipocyte sEV or high glucose/high lipid-challenged nondiabetic adipocyte sEV significantly exacerbated MI/R injury. Diabetic epididymal fat transplantation significantly increased MI/R injury in nondiabetic mice, whereas administration of a sEV biogenesis inhibitor significantly mitigated MI/R injury in diabetic mice. A mechanistic investigation identified that miR-130b-3p is a common molecule significantly increased in diabetic serum sEV, diabetic adipocyte sEV, and high glucose/high lipid-challenged nondiabetic adipocyte sEV. Mature (but not primary) miR-130b-3p was significantly increased in the diabetic and nondiabetic heart subjected to diabetic sEV injection. Whereas intramyocardial injection of a miR-130b-3p mimic significantly exacerbated MI/R injury in nondiabetic mice, miR-130b-3p inhibitors significantly attenuated MI/R injury in diabetic mice. Molecular studies identified AMPKα1/α2, Birc6, and Ucp3 as direct downstream targets of miR-130b-3p. Overexpression of these molecules (particularly AMPKα2) reversed miR-130b-3p induced proapoptotic/cardiac harmful effect. Finally, miR-130b-3p levels were significantly increased in plasma sEV from patients with type 2 diabetes mellitus. Incubation of cardiomyocytes with diabetic patient sEV significantly exacerbated ischemic injury, an effect blocked by miR-130b-3p inhibitor.Conclusions: We demonstrate for the first time that miR-130b-3p enrichment in dysfunctional adipocyte-derived sEV, and its suppression of multiple antiapoptotic/cardioprotective molecules in cardiomyocytes, is a novel mechanism exacerbating MI/R injury in the diabetic heart. Targeting miR-130b-3p mediated pathological communication between dysfunctional adipocytes and cardiomyocytes may be a novel strategy attenuating diabetic exacerbation of MI/R injury. [ABSTRACT FROM AUTHOR]

Background: C1q/tumor necrosis factor-related protein-9 (CTRP9) is a newly identified adiponectin paralog with established metabolic regulatory properties. However, the role of CTRP9 in postmyocardial infarction remodeling remains completely unknown. This study determined whether CTRP9 may regulate cardiac remodeling after acute myocardial infarction (AMI) and elucidated the underlying mechanisms.Methods and Results: Male adult mice were subject to AMI by left anterior descending coronary artery ligation or sham surgery and treated with saline (vehicle) or globular CTRP9 via peritoneal implant osmotic pumps for 6 weeks. H9C2 cardiac cell lines were used in vitro for determining underlying mechanisms. Adipocyte CTRP9 expression and plasma CTRP9 levels were both significantly reduced after AMI. Compared with vehicle, CTRP9 treatment improved animal survival rate (P<0.05), restored cardiac function (P<0.05), attenuated adverse remodeling (P<0.01), and ameliorated cardiomyocyte apoptosis and fibrosis after AMI (P<0.01). Among the multiple antiremodeling molecules determined, AMP-activated protein kinase, protein kinase A (PKA), and Akt were significantly activated in CTRP9-treated heart. Surprisingly, CTRP9 remains cardioprotective in mice with cardiomyocyte-specific overexpression of a mutant AMP-activated protein kinase α2 subunit (AMPK-DN). Additional in vitro experiments demonstrated that administration of either PKA inhibitor or PKA-specific small interfering RNA virtually abolished the antiapoptotic effect of CTRP9 (P<0.05), whereas inhibition of Akt is less effective in blocking CTRP9 cardioprotection. Finally, CTRP9 phosphorylates BCL-2-associated agonist of cell death at its multiple antiapoptotic sites, an effect blocked by PKA inhibitor.Conclusions: We demonstrate that adipokine CTRP9 attenuates adverse cardiac remodeling after AMI, largely via a PKA-dependent pathway. [ABSTRACT FROM AUTHOR]