Cardiac Aging Is Promoted by Pseudohypoxia Increasing p300-Induced Glycolysis.

BACKGROUND: Heart failure is typical in the elderly. Metabolic remodeling of cardiomyocytes underlies inexorable deterioration of cardiac function with aging: glycolysis increases at the expense of oxidative phosphorylation, causing an energy deficit contributing to impaired contractility. Better understanding of the mechanisms of this metabolic switching could be critical for reversing the condition. METHODS: To investigate the role of 3 histone modifications (H3K27ac, H3K27me3, and H3K4me1) in the metabolic remodeling occurring in the aging heart, we cross-compared epigenomic, transcriptomic, and metabolomic data from mice of different ages. In addition, the role of the transcriptional coactivator p300 (E1A-associated binding protein p300)/CBP (CREB binding protein) in cardiac aging was investigated using a specific inhibitor of this histone acetyltransferase enzyme. RESULTS: We report a set of species-conserved enhancers associated with transcriptional changes underlying age-related metabolic remodeling in cardiomyocytes. Activation of the enhancer region of Hk2-a key glycolysis pathway gene-was fostered in old age-onset mouse heart by pseudohypoxia, wherein hypoxia-related genes are expressed under normal O2 levels, via increased activity of P300/CBP. Pharmacological inhibition of this transcriptional coactivator before the onset of cardiac aging led to a more aerobic, less glycolytic, metabolic state, improved heart contractility, and overall blunting of cardiac decline. CONCLUSIONS: Taken together, our results suggest how epigenetic dysregulation of glycolysis pathway enhancers could potentially be targeted to treat heart failure in the elderly.

rs41291957 controls miR-143 and miR-145 expression and impacts coronary artery disease risk.

The role of single nucleotide polymorphisms (SNPs) in the etiopathogenesis of cardiovascular diseases is well known. The effect of SNPs on disease predisposition has been established not only for protein coding genes but also for genes encoding microRNAs (miRNAs). The miR-143/145 cluster is smooth muscle cell-specific and implicated in the pathogenesis of atherosclerosis. Whether SNPs within the genomic sequence of the miR-143/145 cluster are involved in cardiovascular disease development is not known. We thus searched annotated sequence databases for possible SNPs associated with miR-143/145. We identified one SNP, rs41291957 (G > A), located -91 bp from the mature miR-143 sequence, as the nearest genetic variation to this miRNA cluster, with a minor allele frequency > 10%. In silico and in vitro approaches determined that rs41291957 (A) upregulates miR-143 and miR-145, modulating phenotypic switching of vascular smooth cells towards a differentiated/contractile phenotype. Finally, we analysed association between rs41291957 and CAD in two cohorts of patients, finding that the SNP was a protective factor. In conclusion, our study links a genetic variation to a pathological outcome through involvement of miRNAs.

Myocardial hypoxic stress mediates functional cardiac extracellular vesicle release.

AIMS: Increased shedding of extracellular vesicles (EVs)-small, lipid bilayer-delimited particles with a role in paracrine signalling-has been associated with human pathologies, e.g. atherosclerosis, but whether this is true for cardiac diseases is unknown. METHODS AND RESULTS: Here, we used the surface antigen CD172a as a specific marker of cardiomyocyte (CM)-derived EVs; the CM origin of CD172a+ EVs was supported by their content of cardiac-specific proteins and heart-enriched microRNAs. We found that patients with aortic stenosis, ischaemic heart disease, or cardiomyopathy had higher circulating CD172a+ cardiac EV counts than did healthy subjects. Cellular stress was a major determinant of EV release from CMs, with hypoxia increasing shedding in in vitro and in vivo experiments. At the functional level, EVs isolated from the supernatant of CMs derived from human-induced pluripotent stem cells and cultured in a hypoxic atmosphere elicited a positive inotropic response in unstressed CMs, an effect we found to be dependent on an increase in the number of EVs expressing ceramide on their surface. Of potential clinical relevance, aortic stenosis patients with the highest counts of circulating cardiac CD172a+ EVs had a more favourable prognosis for transcatheter aortic valve replacement than those with lower counts. CONCLUSION: We identified circulating CD172a+ EVs as cardiac derived, showing their release and function and providing evidence for their prognostic potential in aortic stenosis patients.

Neutrophil Gelatinase-Associated Lipocalin and Contrast-Induced Acute Kidney Injury.

BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) is an early marker of acute kidney injury (AKI). METHODS AND RESULTS: Urine NGAL and serum NGAL (sNGAL) were assessed at 2, 6, 24, and 48 hours after contrast media (CM) exposure in 458 high-risk patients (development set). Optimal thresholds in predicting contrast-induced AKI (serum creatinine [sCr] increase ≥0.3 mg/dL at 48 hours after CM administration) were identified. Major adverse events (MAE; death, dialysis, nonfatal myocardial infarction, sustained kidney injury, and myocardial revascularization) at 1 year were assessed. In the development set, optimal thresholds for contrast-induced AKI occurred at 6 hours for both urine NGAL (≥20 ng/mL; 97% negative predictive value and 27% positive predictive value) and sNGAL (≥179 ng/mL; 93% negative predictive value and 20% positive predictive value). Furthermore, sNGAL ≥179 ng/mL at 6 hours was an independent predictor of 1-year MAE. 1-year MAE occurred in 27/198 patients (13.5%) with sNGAL <179 ng/mL and sCr <0.3 mg/dL, in 57/193 (29.5%) patients with only sNGAL ≥179 ng/mL, and in 37/67 (55%) patients with sCr ≥0.3 mg/dL. In additional 253 patients (validation set), no patient with urine NGAL <20 ng/mL or sNGAL <179 ng/mL at 6 hours developed contrast-induced AKI. Furthermore, 6/68 (9%) patients with sNGAL <179 ng/mL and sCr increase <0.3 mg/dL had 1-year MAE versus 17/57 (30%) patients with sNGAL ≥179 ng/mL and sCr increase <0.3 mg/dL and 8/16 (50%) patients with sCr increase ≥0.3 mg/dL. CONCLUSIONS: Urine NGAL <20 ng/mL and sNGAL <179 ng/mL at 6 hours are reliable markers for ruling out contrast-induced AKI. sNGAL ≥179 ng/mL at 6 hours predicts 1-year MAE. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01098032.

Circulating miR-29a, among other up-regulated microRNAs, is the only biomarker for both hypertrophy and fibrosis in patients with hypertrophic cardiomyopathy.

OBJECTIVES: The purpose of this paper was to determine whether microRNAs (miRNAs) involved in myocardial remodeling were differentially expressed in the blood of hypertrophic cardiomyopathy (HCM) patients, and whether circulating miRNAs correlated with the degree of left ventricular hypertrophy and fibrosis. BACKGROUND: miRNAs-small, noncoding ribonucleic acids (RNAs) that regulate gene expression by inhibiting RNA translation-modulate cellular function. Myocardial miRNAs modulate processes such as cardiomyocyte (CM) hypertrophy, excitation-contraction coupling, and apoptosis; non-CM-specific miRNAs regulate myocardial vascularization and fibrosis. Recently, the possibility that circulating miRNAs may be biomarkers of cardiovascular disease has been raised. METHODS: Forty-one HCM patients were characterized with conventional transthoracic echocardiography and cardiac magnetic resonance. Peripheral plasma levels of 21 miRNAs were assessed by quantitative real-time polymerase chain reaction and were compared with levels in a control group of 41 age- and sex-matched blood donors. RESULTS: Twelve miRNAs (miR-27a, -199a-5p, -26a, -145, -133a, -143, -199a-3p, -126-3p, -29a, -155, -30a, and -21) were significantly increased in HCM plasma. However, only 3 miRNAs (miR-199a-5p, -27a, and -29a) correlated with hypertrophy; more importantly, only miR-29a correlated also with fibrosis. CONCLUSIONS: Our data suggest that cardiac remodeling associated with HCM determines a significant release of miRNAs into the bloodstream: the circulating levels of both cardiac- and non-cardiac-specific miRNAs are significantly increased in the plasma of HCM patients. However, correlation with left ventricular hypertrophy parameters holds true for only a few miRNAs (i.e., miR-199a-5p, -27a, and -29a), whereas only miR-29a is significantly associated with both hypertrophy and fibrosis, identifying it as a potential biomarker for myocardial remodeling assessment in HCM.

Routine assessment of on-clopidogrel platelet reactivity and gene polymorphisms in predicting clinical outcome following drug-eluting stent implantation in patients with stable coronary artery disease.

OBJECTIVES: This study sought to assess the usefulness of clopidogrel-pathway genotyping and on-treatment platelet reactivity (OTR) testing in predicting major adverse cardiac events (MACE) in stable coronary artery disease (CAD) patients receiving drug-eluting stents (DES) under dual antiplatelet (clopidogrel plus aspirin) therapy. BACKGROUND: The role of pharmacogenetics and OTR in predicting MACE-death, myocardial infarction, or stent thrombosis-in stable CAD patients scheduled for DES implantation is still debated. METHODS: Patients with stable CAD treated by DES implantation (n = 1,432) were genotyped with a TaqMan OpenArray (Applied Biosystems, Carlsbad, California) and assessed for OTR with the VerifyNow P2Y12 test (Accumetrics Inc., San Diego, California). Genes tested were ABCB1, CYP1A2, CYP2B6*9, CYP2C8*3, CYP2C9*2, CYP2C19, CYP3A4, CYP3A5*3, P2RY12, and PON1CYP2C19. High OTR was defined as P2Y12 reaction units ≥230. The endpoint at 12-month follow-up was MACE occurring during antiplatelet therapy. RESULTS: All groups that were stratified for loss-of-function variants of the cytochrome P450 gene CYP2C19 had significant hazard ratios (HR) for MACE (genotypic HR: 1.41, 95% confidence interval [CI]: 1.06 to 1.89, p = 0.01; allelic HR: 1.56, 95% CI: 2.26 to 1.2, p = 0.01). Variants of other clopidogrel-pathway genes were not significantly associated with MACE. When OTR was assessed, clinical significance was found only in high-risk diabetic (HR: 2.11, 95% CI: 1.29 to 3.45, p < 0.001) and chronic kidney disease (HR: 2.03, 95% CI: 1.03 to 4.02, p = 0.04) patients. CONCLUSIONS: CYP2C19 metabolizer status is an independent predictor of MACE after DES implantation and can be used for prognostication in all stable CAD patients. High OTR, as assessed by the VerifyNow P2Y12 test, is an independent predictor of MACE only for high-risk subsets, that is, patients with diabetes or chronic kidney disease.

Doubly heterozygous LMNA and TTN mutations revealed by exome sequencing in a severe form of dilated cardiomyopathy.

Familial dilated cardiomyopathy (DCM) is a heterogeneous disease; although 30 disease genes have been discovered, they explain only no more than half of all cases; in addition, the causes of intra-familial variability in DCM have remained largely unknown. In this study, we exploited the use of whole-exome sequencing (WES) to investigate the causes of clinical variability in an extended family with 14 affected subjects, four of whom showed particular severe manifestations of cardiomyopathy requiring heart transplantation in early adulthood. This analysis, followed by confirmative conventional sequencing, identified the mutation p.K219T in the lamin A/C gene in all 14 affected patients. An additional variant in the gene for titin, p.L4855F, was identified in the severely affected patients. The age for heart transplantation was substantially less for LMNA:p.K219T/TTN:p.L4855F double heterozygotes than that for LMNA:p.K219T single heterozygotes. Myocardial specimens of doubly heterozygote individuals showed increased nuclear length, sarcomeric disorganization, and myonuclear clustering compared with samples from single heterozygotes. In conclusion, our results show that WES can be used for the identification of causal and modifier variants in families with variable manifestations of DCM. In addition, they not only indicate that LMNA and TTN mutational status may be useful in this family for risk stratification in individuals at risk for DCM but also suggest titin as a modifier for DCM.