Atorvastatin and blood flow regulate expression of distinctive sets of genes in mouse carotid artery endothelium.

Hypercholesterolemia is a well-known pro-atherogenic risk factor and statin is the most effective anti-atherogenic drug that lowers blood cholesterol levels. However, despite systemic hypercholesterolemia, atherosclerosis preferentially occurs in arterial regions exposed to disturbed blood flow (d-flow), while the stable flow (s-flow) regions are spared. Given their predominant effects on endothelial function and atherosclerosis, we tested whether (1) statin and flow regulate the same or independent sets of genes and (2) statin can rescue d-flow-regulated genes in mouse artery endothelial cells in vivo. To test the hypotheses, C57BL/6 J mice (8-week-old male, n=5 per group) were pre-treated with atorvastatin (10mg/kg/day, Orally) or vehicle for 5 days. Thereafter, partial carotid ligation (PCL) surgery to induce d-flow in the left carotid artery (LCA) was performed, and statin or vehicle treatment was continued. The contralateral right carotid artery (RCA) remained exposed to s-flow to be used as the control. Two days or 2 weeks post-PCL surgery, endothelial-enriched RNAs from the LCAs and RCAs were collected and subjected to microarray gene expression analysis. Statin treatment in the s-flow condition (RCA+statin versus RCA+vehicle) altered the expression of 667 genes at 2-day and 187 genes at 2-week timepoint, respectively (P<0.05, fold change (FC)≥±1.5). Interestingly, statin treatment in the d-flow condition (LCA+statin versus LCA+vehicle) affected a limited number of genes: 113 and 75 differentially expressed genes at 2-day and 2-week timepoint, respectively (P<0.05, FC≥±1.5). In contrast, d-flow in the vehicle groups (LCA+vehicle versus RCA+vehicle) differentially regulated 4061 genes at 2-day and 3169 genes at 2-week timepoint, respectively (P<0.05, FC≥±1.5). Moreover, statin treatment did not reduce the number of flow-sensitive genes (LCA+statin versus RCA+statin) compared to the vehicle groups: 1825 genes at 2-day and 3788 genes at 2-week, respectively, were differentially regulated (P<0.05, FC≥±1.5). These results revealed that both statin and d-flow regulate expression of hundreds or thousands of arterial endothelial genes, respectively, in vivo. Further, statin and d-flow regulate independent sets of endothelial genes. Importantly, statin treatment did not reverse d-flow-regulated genes except for a small number of genes. These results suggest that both statin and flow play important independent roles in atherosclerosis development and highlight the need to consider their therapeutic implications for both.

Very late vasomotor responses and gene expression with bioresorbable scaffolds and metallic drug-eluting stents.

OBJECTIVES: To investigate the long-term vasomotor response and inflammatory changes in Absorb bioresorbable vascular scaffold (BVS) and metallic drug-eluting stent (DES) implanted artery. BACKGROUND: Clinical evidence has demonstrated that compared to DES, BVS is associated with higher rates of target lesion failure. However, it is not known whether the higher event rates observed with BVS are related to endothelial dysfunction or inflammation associated with polymer degradation. METHODS: Ten Absorb BVS and six Xience V DES were randomly implanted in the main coronaries of six nonatherosclerotic swine. At 4-years, vasomotor response was evaluated in vivo by quantitative coronary angiography response to intracoronary infusion of Ach and ex vivo by the biomechanical response to prostaglandin F2-α (PGF2-α), substance P and bradykinin and gene expression analysis. RESULTS: Absorb BVS implanted arteries showed significantly restored vasoconstrictive responses after Ach compared to in-stent Xience V. The contractility of Absorb BVS treated segments induced by PGF2-α was significantly greater compared to Xience V treated segments and endothelial-dependent vasorelaxation was greater with Absorb BVS compared to Xience V. Gene expression analyses indicated the pro-inflammatory lymphotoxin-beta receptor (LTßR) signaling pathway was significantly upregulated in arteries treated with a metallic stent compared to Absorb BVS treated arterial segments. CONCLUSIONS: At 4 years, arteries treated with Absorb BVS compared with Xience V, demonstrate significantly greater restoration of vasomotor responses. Genetic analysis suggests mechanobiologic reparation of Absorb BVS treated arteries at 4 years as opposed to Xience V treated vessels.

Role of flow-sensitive microRNAs and long noncoding RNAs in vascular dysfunction and atherosclerosis.

Atherosclerosis is the primary underlying cause of myocardial infarction, ischemic stroke, and peripheral artery disease. The disease preferentially occurs in arterial regions exposed to disturbed blood flow, in part, by altering expression of flow-sensitive coding- and non-coding genes. In this review, we summarize the role of noncoding RNAs, [microRNAs (miRNAs) and long noncoding RNAs(lncRNAs)], as regulators of gene expression and outline their relationship to the pathogenesis of atherosclerosis. While miRNAs are small noncoding genes that post-transcriptionally regulate gene expression by targeting mRNA transcripts, the lncRNAs regulate gene expression by diverse mechanisms, which are still emerging and incompletely understood. We focused on multiple flow-sensitive miRNAs such as, miR-10a, -19a, -23b, -17~92, -21, -663, -92a, -143/145, -101, -126, -712, -205, and -155 that play a critical role in endothelial function and atherosclerosis by targeting inflammation, cell cycle, proliferation, migration, apoptosis, and nitric oxide signaling. Flow-dependent regulation of lncRNAs is just emerging, and their role in vascular dysfunction and atherosclerosis is unknown. Here, we discuss the flow-sensitive lncRNA STEEL along with other lncRNAs studied in the context of vascular pathophysiology and atherosclerosis such as MALAT1, MIAT1, ANRIL, MYOSLID, MEG3, SENCR, SMILR, LISPR1, and H19. Also discussed is the use of these noncoding RNAs as potential biomarkers and therapeutics to reduce and regress atherosclerosis.

Omics-based approaches to understand mechanosensitive endothelial biology and atherosclerosis.

Atherosclerosis is a multifactorial disease that preferentially occurs in arterial regions exposed to d-flow can be used to indicate disturbed flow or disturbed blood flow. The mechanisms by which d-flow induces atherosclerosis involve changes in the transcriptome, methylome, proteome, and metabolome of multiple vascular cells, especially endothelial cells. Initially, we begin with the pathogenesis of atherosclerosis and the changes that occur at multiple levels owing to d-flow, especially in the endothelium. Also, there are a variety of strategies used for the global profiling of the genome, transcriptome, miRNA-ome, DNA methylome, and metabolome that are important to define the biological and pathophysiological mechanisms of endothelial dysfunction and atherosclerosis. Finally, systems biology can be used to integrate these 'omics' datasets, especially those that derive data based on a single animal model, in order to better understand the pathophysiology of atherosclerosis development in a holistic manner and how this integrative approach could be used to identify novel molecular diagnostics and therapeutic targets to prevent or treat atherosclerosis. WIREs Syst Biol Med 2016, 8:378-401. doi: 10.1002/wsbm.1344 For further resources related to this article, please visit the WIREs website.

Comparison of sum absolute QRST integral, and temporal variability in depolarization and repolarization, measured by dynamic vectorcardiography approach, in healthy men and women.

BACKGROUND: Recently we showed the predictive value of sum absolute QRST integral (SAI QRST) and repolarization lability for risk stratification of sudden cardiac death (SCD) in heart failure patients. The goal of this study was to compare SAI QRST and metrics of depolarization and repolarization variability in healthy men and women. METHODS: Orthogonal ECGs were recorded at rest for 10 minutes in 160 healthy men and women (mean age 39.6±14.6, 80 men). Mean spatial TT' angle, and normalized variances of T loop area, of spatial T vector amplitude, of QT interval and Tpeak-Tend area were measured for assessment of repolarization lability. Normalized variances of spatial QRS vector and QRS loop area characterized variability of depolarization. In addition, variability indices (VI) were calculated to adjust for normalized heart rate variance. SAI QRST was measured as the averaged arithmetic sum of areas under the QRST curve. RESULTS: Men were characterized by shorter QTc (430.3±21.7 vs. 444.7±22.2 ms; P<0.0001) and larger SAI QRST (282.1±66.7 vs. 204.9±58.5 mV*ms; P<0.0001). Repolarization lability negatively correlated with spatial T vector amplitude. Adjusted by normalized heart rate variance, QT variability index was significantly higher in women than in men (-1.54±0.38 vs. -1.70±0.33; P = 0.017). However, in multivariate logistic regression after adjustment for body surface area, QTc, and spatial T vector amplitude, healthy men had 1.5-3 fold higher probability of having larger repolarization lability, as compared to healthy women (T vector amplitude variability index odds ratio 3.88 (95%CI 1.4-11.1; P = 0.012). CONCLUSIONS: Healthy men more likely than women have larger repolarization lability.

Intracardiac J-point elevation before the onset of polymorphic ventricular tachycardia and ventricular fibrillation in patients with an implantable cardioverter-defibrillator.

BACKGROUND: The clinical importance of the J-point elevation on electrocardiogram is controversial. OBJECTIVE: To study intracardiac J-point amplitude before ventricular arrhythmia. METHODS: Baseline 12-lead electrocardiogram and far-field right ventricular intracardiac implantable cardioverter-defibrillator electrograms were recorded at rest in 494 patients (mean age 60.4 ± 13.1 years; 360 [72.9%] men) with structural heart disease (278 [56.3%] ischemic cardiomyopathy) who received primary (463 [93.9%] patients) or secondary prevention implantable cardioverter-defibrillator. Ten-second intracardiac far-field electrograms before the onset of arrhythmia were compared with the baseline. The J-point amplitude was measured on the baseline 12-lead surface electrocardiogram and the intracardiac far-field electrogram. The relative J-point amplitude was calculated as the ratio of J-point amplitude to peak-to-peak R-wave. RESULTS: The paired t test showed that the relative intracardiac J-point amplitude was significantly higher before polymorphic ventricular tachycardia/ventricular fibrillation (VF) onset (0.28 ± 0.08 vs -0.19 ± 0.39; P = .012) than at baseline. In a mixed-effects logistic regression model, adjusted for multiple episodes per patient, each 10% increase in relative J-point amplitude increased the odds of having ventricular tachycardia/VF by 13% (odds ratio 1.13 [95% confidence interval 1.07-1.19]; P < .0001) and increased the odds of having polymorphic ventricular tachycardia/VF by 27% (odds ratio 1.27 [95% confidence interval 1.11-1.46]; P = .001). CONCLUSIONS: The relative intracardiac J-point amplitude is augmented immediately before the onset of polymorphic ventricular tachycardia/VF in patients with structural heart disease.

Predictive value of beat-to-beat QT variability index across the continuum of left ventricular dysfunction: competing risks of noncardiac or cardiovascular death and sudden or nonsudden cardiac death.

BACKGROUND: The goal of the present study was to determine the predictive value of beat-to-beat QT variability in heart failure patients across the continuum of left ventricular dysfunction. METHODS AND RESULTS: Beat-to-beat QT variability index (QTVI), log-transformed heart rate variance, normalized QT variance, and coherence between heart rate variability and QT variability have been measured at rest during sinus rhythm in 533 participants of the Muerte Subita en Insuficiencia Cardiaca heart failure study (mean age, 63.1±11.7; men, 70.6%; left ventricular ejection fraction >35% in 254 [48%]) and in 181 healthy participants from the Intercity Digital Electrocardiogram Alliance database. During a median of 3.7 years of follow-up, 116 patients died, 52 from sudden cardiac death (SCD). In multivariate competing risk analyses, the highest QTVI quartile was associated with cardiovascular death (subhazard ratio, 1.67 [95% CI, 1.14-2.47]; P=0.009) and, in particular, with non-SCD (subhazard ratio, 2.91 [1.69-5.01]; P<0.001). Elevated QTVI separated 97.5% of healthy individuals from subjects at risk for cardiovascular (subhazard ratio, 1.57 [1.04-2.35]; P=0.031) and non-SCD in multivariate competing risk model (subhazard ratio, 2.58 [1.13-3.78]; P=0.001). No interaction between QTVI and left ventricular ejection fraction was found. QTVI predicted neither noncardiac death (P=0.546) nor SCD (P=0.945). Decreased heart rate variability rather than increased QT variability was the reason for increased QTVI in the present study. CONCLUSIONS: Increased QTVI because of depressed heart rate variability predicts cardiovascular mortality and non-SCD but neither SCD nor extracardiac mortality in heart failure across the continuum of left ventricular dysfunction. Abnormally augmented QTVI separates 97.5% of healthy individuals from heart failure patients at risk.