Multiomics of Tissue Extracellular Vesicles Identifies Unique Modulators of Atherosclerosis and Calcific Aortic Valve Stenosis.

BACKGROUND: Fewer than 50% of patients who develop aortic valve calcification have concomitant atherosclerosis, implying differential pathogenesis. Although circulating extracellular vesicles (EVs) act as biomarkers of cardiovascular diseases, tissue-entrapped EVs are associated with early mineralization, but their cargoes, functions, and contributions to disease remain unknown. METHODS: Disease stage-specific proteomics was performed on human carotid endarterectomy specimens (n=16) and stenotic aortic valves (n=18). Tissue EVs were isolated from human carotid arteries (normal, n=6; diseased, n=4) and aortic valves (normal, n=6; diseased, n=4) by enzymatic digestion, (ultra)centrifugation, and a 15-fraction density gradient validated by proteomics, CD63-immunogold electron microscopy, and nanoparticle tracking analysis. Vesiculomics, comprising vesicular proteomics and small RNA-sequencing, was conducted on tissue EVs. TargetScan identified microRNA targets. Pathway network analyses prioritized genes for validation in primary human carotid artery smooth muscle cells and aortic valvular interstitial cells. RESULTS: Disease progression drove significant convergence (P<0.0001) of carotid artery plaque and calcified aortic valve proteomes (2318 proteins). Each tissue also retained a unique subset of differentially enriched proteins (381 in plaques; 226 in valves; q<0.05). Vesicular gene ontology terms increased 2.9-fold (P<0.0001) among proteins modulated by disease in both tissues. Proteomics identified 22 EV markers in tissue digest fractions. Networks of proteins and microRNA targets changed by disease progression in both artery and valve EVs revealed shared involvement in intracellular signaling and cell cycle regulation. Vesiculomics identified 773 proteins and 80 microRNAs differentially enriched by disease exclusively in artery or valve EVs (q<0.05); multiomics integration found tissue-specific EV cargoes associated with procalcific Notch and Wnt signaling in carotid arteries and aortic valves, respectively. Knockdown of tissue-specific EV-derived molecules FGFR2, PPP2CA, and ADAM17 in human carotid artery smooth muscle cells and WNT5A, APP, and APC in human aortic valvular interstitial cells significantly modulated calcification. CONCLUSIONS: The first comparative proteomics study of human carotid artery plaques and calcified aortic valves identifies unique drivers of atherosclerosis versus aortic valve stenosis and implicates EVs in advanced cardiovascular calcification. We delineate a vesiculomics strategy to isolate, purify, and study protein and RNA cargoes from EVs entrapped in fibrocalcific tissues. Integration of vesicular proteomics and transcriptomics by network approaches revealed novel roles for tissue EVs in modulating cardiovascular disease.

The Impact of COVID-19 on Racial and Ethnic Disparities in Cardiac Procedural Care.

OBJECTIVE: The primary objective of this study was to evaluate whether the COVID-19 pandemic altered the racial and ethnic composition of patients receiving cardiac procedural care. DESIGN: This was a retrospective observational study. SETTING: This study was conducted at a single tertiary-care university hospital. PARTICIPANTS: A total of 1,704 adult patients undergoing transcatheter aortic valve replacement (TAVR) (n = 413), coronary artery bypass grafting (CABG) (n = 506), or atrial fibrillation (AF) ablation (n = 785) from March 2019 through March 2022 were included in this study. INTERVENTIONS: No interventions were performed as this was a retrospective observational study. MEASUREMENTS AND MAIN RESULTS: Patients were grouped based on the date of their procedure: pre-COVID (March 2019 to February 2020), COVID Year 1 (March 2020 to February 2021), and COVID Year 2 (March 2021 to March 2022). Population-adjusted procedural incidence rates during each period were examined and stratified based on race and ethnicity. The procedural incidence rate was higher for White patients versus Black, and non-Hispanic patients versus Hispanic patients for every procedure and every period. For TAVR, the difference in procedural rates between White patients versus Black patients decreased between the pre-COVID and COVID Year 1 (12.05-6.34 per 1,000,000 persons). For CABG, the difference in procedural rates between White patients versus Black, and non-Hispanic patients versus Hispanic patients did not change significantly. For AF ablations, the difference in procedural rates between White patients versus Black patients increased over time (13.06 to 21.55 to 29.64 per 1,000,000 persons in the pre-COVID, COVID Year 1, and COVID Year 2, respectively). CONCLUSION: Racial and ethnic disparities in access to cardiac procedural care were present throughout all study time periods at the authors' institution. Their findings reinforce the continuing need for initiatives to reduce racial and ethnic disparities in healthcare. Further studies are needed to fully elucidate the effects of the COVID-19 pandemic on healthcare access and delivery.

Incidence of Intraoperative Vasoplegic Syndrome in Lung Transplantation.

OBJECTIVES: Severe hypotension and low systemic vascular resistance in the setting of adequate cardiac output, known as "vasoplegic syndrome" (VS), is a physiologic disturbance reported in 9% to 44% of cardiac surgery patients. Although this phenomenon is well-documented in cardiac surgery, there are few studies on its occurrence in lung transplantation. The goal of this study was to characterize the incidence of VS in lung transplantation, as well as identify associated risk factors and outcomes. DESIGN: Retrospective study of single and bilateral lung transplants from April 2013 to September 2021. SETTING: The study was conducted at an academic hospital. PARTICIPANTS: Patients ≥18 years of age who underwent lung transplantation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The authors defined VS as mean arterial pressure <65 mmHg, cardiac index ≥2.2 L/min/m2, and ≥30 minutes of vasopressor administration after organ reperfusion. The association between VS and risk factors or outcomes was assessed using t tests, Mann-Whitney U, and chi-square tests. The authors ran multivariate logistic regression models to determine factors independently associated with VS. The incidence of VS was 13.9% (CI 10.4%-18.4%). In the multivariate model, male sex (odds ratio 2.85, CI 1.07-7.58, p = 0.04) and cystic fibrosis (odds ratio 5.76, CI 1.43-23.09, p = 0.01) were associated with VS. CONCLUSIONS: The incidence of VS in lung transplantation is comparable to that of cardiac surgery. Interestingly, male sex and cystic fibrosis are strong risk factors. Identifying lung transplant recipients at increased risk of VS may be crucial to anticipating intraoperative complications.

17 ß-Estradiol Impedes Aortic Root Dilation and Rupture in Male Marfan Mice.

Marfan syndrome causes a hereditary form of thoracic aortic aneurysms with worse outcomes in male compared to female patients. In this study, we examine the effects of 17 ß-estradiol on aortic dilation and rupture in a Marfan mouse model. Marfan male mice were administered 17 ß-estradiol, and the growth in the aortic root, along with the risk of aortic rupture, was measured. Transcriptomic profiling was used to identify enriched pathways from 17 ß-estradiol treatments. Aortic smooth muscle cells were then treated with cytokines to validate functional mechanisms. We show that 17 ß-estradiol decreased the size and rate of aortic root dilation and improved survival from rupture. The Marfan transcriptome was enriched in inflammatory genes, and the addition of 17 ß-estradiol modulated a set of genes that function through TNFα mediated NF-κB signaling. In addition, 17 ß-estradiol suppressed the induction of these TNFα induced genes in aortic smooth muscle cells in vitro in an NF-κB dependent manner, and 17 ß-estradiol decreased the formation of adventitial inflammatory foci in aortic roots in vivo. In conclusion, 17 ß-estradiol protects against the dilation and rupture of aortic roots in Marfan male mice through the inhibition of TNFα-NF-κB signaling.

Variant curation expert panel recommendations for RYR1 pathogenicity classifications in malignant hyperthermia susceptibility.

PURPOSE: As a ClinGen Expert Panel (EP) we set out to adapt the American College of Medical Genetics and Genomics (ACMG)/Association for Molecular Pathology (AMP) pathogenicity criteria for classification of RYR1 variants as related to autosomal dominantly inherited malignant hyperthermia (MH). METHODS: We specified ACMG/AMP criteria for variant classification for RYR1 and MH. Proposed rules were piloted on 84 variants. We applied quantitative evidence calibration for several criteria using likelihood ratios based on the Bayesian framework. RESULTS: Seven ACMG/AMP criteria were adopted without changes, nine were adopted with RYR1-specific modifications, and ten were dropped. The in silico (PP3 and BP4) and hotspot criteria (PM1) were evaluated quantitatively. REVEL gave an odds ratio (OR) of 23:1 for PP3 and 14:1 for BP4 using trichotomized cutoffs of ≥0.85 (pathogenic) and ≤0.5 (benign). The PM1 hotspot criterion had an OR of 24:1. PP3 and PM1 were implemented at moderate strength. Applying the revised ACMG/AMP criteria to 44 recognized MH variants, 29 were classified as pathogenic, 13 as likely pathogenic, and 2 as variants of uncertain significance. CONCLUSION: Curation of these variants will facilitate classification of RYR1/MH genomic testing results, which is especially important for secondary findings analyses. Our approach to quantitatively calibrating criteria is generalizable to other variant curation expert panels.

Intraoperative diastolic function assessed by TEE does not agree with preoperative diastolic function grade in CABG patients.

OBJECTIVE: To compare the agreement of the 2016 ASE/EACVI guidelines for grading diastolic dysfunction (DD) with the most commonly used intraoperative transesophageal echocardiography (TEE)-based diastolic function grading algorithm in cardiac surgical patients, and to describe the contribution of the echocardiographic variables used in the algorithms to any observed differences. DESIGN: Retrospective data analysis. SETTING: University tertiary medical center. PARTICIPANTS: Hundred and one patients undergoing coronary artery bypass grafting (CABG) at a single institution from June 2017 to February 2019. INTERVENTIONS: Preoperative transthoracic echocardiography (TTE) diastolic function grade determined by the 2016 American Society of Echocardiography (ASE)/European Association of Cardiovascular Imaging (EACVI) guidelines was compared to intraoperative diastolic function grade obtained by TEE. MEASUREMENTS AND MAIN RESULTS: Incidence of DD on preoperative TTE was only 19.8%, while 62.3% of patients were graded as having DD on the intraoperative TEE exam. There was grade agreement between TTE and TEE in only 47/101 patients (46.5%). The McNemar test showed poor agreement between the two algorithms (OR for disagreement = 15.33, CI = 4.77-49.30; p < 0.0001). Despite the low incidence of DD on preoperative TTE, mean lateral e' values were significantly lower on TTE compared to TEE (7.7 cm/s vs 9.5 cm/s; p = < 0.0001). CONCLUSIONS: There is strong disagreement between TTE and TEE-based DD grading algorithms. Due to the different echocardiographic variables used in each and the unique clinical settings in which they are applied, they produce fundamentally different results.

Novel and Annotated Long Noncoding RNAs Associated with Ischemia in the Human Heart.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been implicated in the pathogenesis of cardiovascular diseases. We aimed to identify novel lncRNAs associated with the early response to ischemia in the heart. METHODS AND RESULTS: RNA sequencing data gathered from 81 paired left ventricle samples from patients undergoing cardiopulmonary bypass was collected before and after a period of ischemia. Novel lncRNAs were validated with Oxford Nanopore Technologies long-read sequencing. Gene modules associated with an early ischemic response were identified and the subcellular location of selected lncRNAs was determined with RNAscope. A total of 2446 mRNAs, 270 annotated lncRNAs and one novel lncRNA differed in response to ischemia (adjusted p < 0.001, absolute fold change >1.2). The novel lncRNA belonged to a gene module of highly correlated genes that also included 39 annotated lncRNAs. This module associated with ischemia (Pearson correlation coefficient = -0.69, p = 1 × 10-23) and activation of cell death pathways (p < 6 × 10-9). A further nine novel cardiac lncRNAs were identified, of which, one overlapped five cis-eQTL eSNPs for the gene RWD Domain-Containing Sumoylation Enhancer (RWDD3) and was itself correlated with RWDD3 expression (Pearson correlation coefficient -0.2, p = 0.002). CONCLUSION: We have identified 10 novel lncRNAs, one of which was associated with myocardial ischemia and may have potential as a novel therapeutic target or early marker for myocardial dysfunction.

Progression of myocardial ischemia leads to unique changes in immediate-early gene expression in the spinal cord dorsal horn.

The pathological consequences of ischemic heart disease involve signaling through the autonomic nervous system. Although early activation may serve to maintain hemodynamic stability, persistent aberrant sympathoexcitation contributes to the development of lethal arrhythmias and heart failure. We hypothesized that as the myocardium reacts and remodels to ischemic injury over time, there is an analogous sequence of gene expression changes in the thoracic spinal cord dorsal horn, the processing center for incoming afferent fibers from the heart to the central nervous system. Acute and chronic myocardial ischemia (MI) was induced in a large animal model of Yorkshire pigs, and the thoracic dorsal horn of treated pigs, along with control nonischemic pigs, was harvested for transcriptome analysis. We identified 32 differentially expressed genes between healthy and acute ischemia cohorts and 46 differentially expressed genes between healthy and chronic ischemia cohorts. The canonical immediate-early gene c-fos was upregulated after acute MI, along with fosB, dual specificity phosphatase 1 and 2 ( dusp1 and dusp2), and early growth response 2 (egr2). After chronic MI, there was a persistent yet unique activation of immediate-early genes, including fosB, nuclear receptor subfamily 4 group A members 1-3 ( nr4a1, nr4a2, and nr4a3), egr3, and TNF-α-induced protein 3 ( tnfaip3). In addition, differentially expressed genes from the chronic MI signature were enriched in pathways linked to apoptosis, immune regulation, and the stress response. These findings support a dynamic progression of gene expression changes in the dorsal horn with maturation of myocardial injury, and they may explain how early adaptive autonomic nervous system responses can maintain hemodynamic stability, whereas prolonged maladaptive signals can predispose patients to arrhythmias and heart failure. NEW & NOTEWORTHY Activation of the autonomic nervous system after myocardial injury can provide early cardiovascular support or prolonged aberrant sympathoexcitation. The later response can lead to lethal arrhythmias and heart failure. This study provides evidence of ongoing changes in the gene expression signature of the spinal cord dorsal horn as myocardial injury progresses over time. These changes could help explain how an adaptive nervous system response can become maladaptive over time.

Joint analysis of left ventricular expression and circulating plasma levels of Omentin after myocardial ischemia.

BACKGROUND: Omentin-1, also known as Intelectin-1 (ITLN1), is an adipokine with plasma levels associated with diabetes, obesity, and coronary artery disease. Recent studies suggest that ITLN1 can mitigate myocardial ischemic injury but the expression of ITLN1 in the heart itself has not been well characterized. The purpose of this study is to discern the relationship between the expression pattern of ITLN1 RNA in the human heart and the level of circulating ITLN1 protein in plasma from the same patients following myocardial ischemia. METHODS: A large cohort of patients (n = 140) undergoing elective cardiac surgery for aortic valve replacement were enrolled in this study. Plasma and left ventricular biopsy samples were taken at the beginning of cardiopulmonary bypass and after an average of 82 min of ischemic cross clamp time. The localization of ITLN1 in epicardial adipose tissue (EAT) was also further characterized with immunoassays and cell fate transition studies. RESULTS: mRNA expression of ITLN1 decreases in left ventricular tissue after acute ischemia in human patients (mean difference 280.48, p = 0.001) whereas plasma protein levels of ITLN1 increase (mean difference 5.24, p < 0.001). Immunohistochemistry localized ITLN1 to the mesothelium or visceral pericardium of EAT. Epithelial to mesenchymal transition in mesothelial cells leads to a downregulation of ITLN1 expression. CONCLUSIONS: Myocardial injury leads to a decrease in ITLN1 expression in the heart and a corresponding increase in plasma levels. These changes may in part be due to an epithelial to mesenchymal transition of the cells that express ITLN1 following ischemia. Trial Registration Clinicaltrials.gov ID: NCT00985049.

Integrated microRNA and mRNA responses to acute human left ventricular ischemia.

MicroRNAs (miRNAs) play a significant role in ischemic heart disease. Animal models of left ventricular (LV) ischemia demonstrate a unique miRNA profile; however, these models have limitations in describing human disease. In this study, we performed next-generation miRNA and mRNA sequencing on LV tissue from nine patients undergoing cardiac surgery with cardiopulmonary bypass and cardioplegic arrest. Samples were obtained immediately after aortic cross clamping (baseline) and before aortic cross clamp removal (postischemic). Of 1,237 identified miRNAs, 21 were differentially expressed between baseline and postischemic LV samples including the upregulated miRNAs miR-339-5p and miR-483-3p and the downregulated miRNA miR-139-5p. Target prediction analysis of these miRNAs was integrated with mRNA expression from the same LV samples to identify anticorrelated miRNA-mRNA pairs. Gene enrichment studies of candidate mRNA targets demonstrated an association with cardiovascular disease, cell death, and metabolism. Therapeutics that intervene on these miRNAs and their downstream targets may lead to novel mechanisms of mitigating the damage caused by ischemic insults on the human heart.

17 ß-estradiol impedes aortic root dilation and rupture in male Marfan mice.

Marfan syndrome causes a hereditary form of thoracic aortic aneurysms with dilation of the aortic root. Human and animal models suggest a worse phenotype for males compared to females with respect to aneurysm size and risk of dissection. In this study we examine the effects of 17 ß-estradiol on aortic dilation and rupture in a Marfan mouse model. Marfan male mice were administered 17 ß-estradiol and the growth in aortic root size along with the risk of aortic rupture or dissection with the addition of angiotensin II was measured. Transcriptomic profiling was used to identify enriched pathways from 17 ß-estradiol treatment. Aortic smooth muscle cells were then treated with cytokines in order to validate the mechanism of 17 ß-estradiol protection. We show that 17 ß-estradiol decreased the size and rate of aortic root dilation and improved survival from rupture and dissection after treatment with angiotensin II. The Marfan transcriptome was enriched in inflammatory genes and the addition of 17 ß-estradiol modulated a set of genes that function through TNFα mediated NF-κB signaling. These included many proteins known to play a role in the phenotypic shift of aortic smooth muscle cells from a contractile to a more inflammatory-like state such as Vcam-1, Mcp-1, Lgals3, Il-6, Il-1b, and C3. In addition, 17 ß-estradiol suppressed the induction of these TNFα induced genes in aortic smooth muscle cells in vitro and this effect appears to be NF-κB dependent. In conclusion, 17 ß-estradiol protects against the dilation and rupture of aortic roots in Marfan male mice through the inhibition of TNFα -NF-κB signaling and thus prevents the phenotypic switch of aortic smooth muscle cells from a contractile to an inflammatory state.

Proteomic analysis of descending thoracic aorta identifies unique and universal signatures of aneurysm and dissection.

Objective: Very few clinical predictors of descending thoracic aorta dissection have been determined. Although aneurysms can dissect in a size-dependent process, most descending dissections will occur without prior enlargement. We compared the proteomic profiles of normal, dissected, aneurysm, and both aneurysm and dissected descending thoracic aortas to identify novel biomarkers and further understand the molecular pathways that lead to tissue at risk of dissection. Methods: We performed proteomic profiling of descending thoracic aortas with four phenotypes: normal (n = 46), aneurysm (n = 22), dissected (n = 12), and combined aneurysm and dissection (n = 8). Pairwise differential protein expression analyses using a Bayesian approach were then performed to identify common proteins that were dysregulated between each diseased tissue type and control aorta and to uncover unique proteins between aneurysmal and dissected aortas. Network and Markov cluster algorithms of differentially expressed proteins were used to find enriched ontology processes. A convex analysis of mixtures was also performed to identify the molecular subtypes within the different tissue types. Results: The diseased aortas had 71 common differentially expressed proteins compared with the control, including higher amounts of the protein thrombospondin 1. We found 42 differentially expressed proteins between the aneurysm and dissected tissue, with an abundance of apolipoproteins in the former and higher quantities of extracellular matrix proteins in the latter. The convex analysis of mixtures showed enhancement of a molecular subtype enriched in contractile proteins within the control tissue compared with the diseased tissue, in addition to increased proportions of molecular subtypes enriched in inflammation and red blood cell expression in the aneurysmal compared with the dissected tissue. Conclusions: We found some overlapping differentially expressed proteins in aneurysmal and nonaneurysmal descending thoracic aortas at risk of dissection compared with normal aortas. However, we also found uniquely altered molecular pathways that might uncover mechanisms for dissection.

Quantitative Echocardiography Improves Resident Assessment of Left Ventricular Systolic Function.

Background: The use of echocardiography to assess left ventricular ejection fraction (LVEF) is an important component of anesthesiology resident education; however, there is no consensus on the most effective method for teaching this skill set. This study investigates the impact and feasibility of teaching a quantitative LVEF assessment method to anesthesiology residents, compared with teaching visual estimation techniques. Methods: We included all anesthesiology residents rotating through cardiac anesthesia at our institution from August 2020 through March 2021. Participants completed a pretest to assess baseline ability to accurately estimate LVEF. All tests consisted of transthoracic echocardiography images with standard views from 10 patients. Participants were assigned to either a control group that received teaching on visual estimation of LVEF or an intervention group that was taught quantitative LVEF assessment with the Simpson biplane method of discs. After 4 weeks, all participants were administered a postteaching exam. A retention exam was administered an additional 4 weeks later. LVEF accuracy was measured as the absolute difference between their LVEF estimation and the reference value. Results: Control and intervention groups performed similarly on the preteaching exam of LVEF estimation accuracy. Intervention-group residents demonstrated significantly improved accuracy in LVEF assessment on the postteaching exam (3.6% improvement in accuracy, confidence interval [CI], 1.23-5.97; P = .03) compared with the control group (0.60% improvement inaccuracy, CI, -1.77-2.97; P = .62). The observed improvement was not maintained through the retention exam.Conclusions: Addition of quantitative LVEF assessment to traditional teaching of visual LVEF estimation methods significantly improved the diagnostic accuracy of anesthesiology residents' left ventricular systolic function assessment.

Methylation of the retinoblastoma tumor suppressor by SMYD2.

The retinoblastoma tumor suppressor (RB) is a central cell cycle regulator and tumor suppressor. RB cellular functions are known to be regulated by a diversity of post-translational modifications such as phosphorylation and acetylation, raising the possibility that RB may also be methylated in cells. Here we demonstrate that RB can be methylated by SMYD2 at lysine 860, a highly conserved and novel site of modification. This methylation event occurs in vitro and in cells, and it is regulated during cell cycle progression, cellular differentiation, and in response to DNA damage. Furthermore, we show that RB monomethylation at lysine 860 provides a direct binding site for the methyl-binding domain of the transcriptional repressor L3MBTL1. These results support the idea that a code of post-translational modifications exists for RB and helps guide its functions in mammalian cells.

Post-operative atrial fibrillation examined using whole-genome RNA sequencing in human left atrial tissue.

BACKGROUND: Both ambulatory atrial fibrillation (AF) and post-operative AF (poAF) are associated with substantial morbidity and mortality. Analyzing the tissue-specific gene expression in the left atrium (LA) can identify novel genes associated with AF and further the understanding of the mechanism by which previously identified genetic variants associated with AF mediate their effects. METHODS: LA free wall samples were obtained intraoperatively immediately prior to mitral valve surgery in 62 Caucasian individuals. Gene expression was quantified on mRNA harvested from these samples using RNA sequencing. An expression quantitative trait loci (eQTL) analysis was performed, comparing gene expression between different genotypes of 1.0 million genetic markers, emphasizing genomic regions and genes associated with AF. RESULTS: Comparison of whole-genome expression between patients who later developed poAF and those who did not identified 23 differentially expressed genes. These included genes associated with the resting membrane potential modified by potassium currents, as well as genes within Wnt signaling and cyclic GMP metabolism. The eQTL analysis identified 16,139 cis eQTL relationships in the LA, including several involving genes and single nucleotide polymorphisms (SNPs) linked to AF. A previous relationship between rs3744029 and MYOZ1 expression was confirmed, and a novel relationship between rs6795970 and the expression of the SCN10A gene was identified. CONCLUSIONS: The current study is the first analysis of the human LA expression landscape using high-throughput RNA sequencing. Several novel genes and variants likely involved in AF pathogenesis were identified, thus furthering the understanding of how variants associated with AF mediate their effects via altered gene expression. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT00833313 , registered 5. January 2009.

The Long Noncoding RNA Landscape of the Ischemic Human Left Ventricle.

BACKGROUND: The discovery of functional classes of long noncoding RNAs (lncRNAs) has expanded our understanding of the variety of RNA species that exist in cells. In the heart, lncRNAs have been implicated in the regulation of development, ischemic and dilated cardiomyopathy, and myocardial infarction. Nevertheless, there is a limited description of expression profiles for these transcripts in human subjects. METHODS AND RESULTS: We obtained left ventricular tissue from human patients undergoing cardiac surgery and used RNA sequencing to describe an lncRNA profile. We then identified a list of lncRNAs that were differentially expressed between pairs of samples before and after the ischemic insult of cardiopulmonary bypass. The expression of some of these lncRNAs correlates with ischemic time. Coding genes in close proximity to differentially expressed lncRNAs and coding genes that have coordinated expression with these lncRNAs are enriched in functional categories related to myocardial infarction, including heart function, metabolism, the stress response, and the immune system. CONCLUSIONS: We describe a list of lncRNAs that are differentially expressed after ischemia in the human heart. These genes are predicted to function in pathways consistent with myocardial injury. As a result, lncRNAs may serve as novel diagnostic and therapeutic targets for ischemic heart disease. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00985049.

Sarco"MiR" friend or foe: a perspective on the mechanisms of doxorubicin-induced cardiomyopathy.

Anthracyclines are a class of chemotherapeutics used to treat a variety of human cancers including both solid tumors such as breast, ovarian, and lung, as well as malignancies of the blood including leukemia and lymphoma. Despite being extremely effective anti-cancer agents, the application of these drugs is offset by side effects, most notably cardiotoxicity. Many patients treated with doxorubicin (DOX), one of the most common anthracyclines used in oncology, will develop radiographic signs and/or symptoms of cardiomyopathy. Since more and more patients treated with these drugs are surviving their malignancies and manifesting with heart disease, there is particular interest in understanding the mechanisms of anthracycline-induced injury and developing ways to prevent and treat its most feared complication, heart failure. MicroRNAs (miRNAs) are small noncoding RNAs that regulate the expression of mRNAs. Since miRNAs can regulate many mRNAs in a single network they tend to play a crucial role in the pathogenesis of several diseases, including heart failure. Here we present a perspective on a recent work by Roca-Alonso and colleagues who demonstrate a cardioprotective function of the miR-30 family members following DOX-induced cardiac injury. They provide evidence for direct targeting of these miRNAs on key elements of the ß-adrenergic pathway and further show that this interaction regulates cardiac function and apoptosis. These experiments deliver fresh insights into the biology of toxin-induced cardiomyopathy and suggest the potential for novel therapeutic targets.

Allele-specific expression in the human heart and its application to postoperative atrial fibrillation and myocardial ischemia.

BACKGROUND: Allele-specific expression (ASE) is differential expression of each of the two chromosomal alleles of an autosomal gene. We assessed ASE patterns in the human left atrium (LA, n = 62) and paired samples from the left ventricle (LV, n = 76) before and after ischemia, and tested the utility of differential ASE to identify genes associated with postoperative atrial fibrillation (poAF) and myocardial ischemia. METHODS: Following genotyping from whole blood and whole-genome sequencing of LA and LV samples, we called ASE using sequences overlapping heterozygous SNPs using rigorous quality control to minimize false ASE calling. ASE patterns were compared between cardiac chambers and with a validation cohort from cadaveric tissue. ASE patterns in the LA were compared between patients who had poAF and those who did not. Changes in ASE in the LV were compared between paired baseline and post-ischemia samples. RESULTS: ASE was found for 3404 (5.1%) and 8642 (4.0%) of SNPs analyzed in the LA and LV, respectively. Out of 6157 SNPs with ASE analyzed in both chambers, 2078 had evidence of ASE in both LA and LV (p < 0.0001). The SNP with the greatest ASE difference in the LA of patients with and without postoperative atrial fibrillation was within the gelsolin (GSN) gene, previously associated with atrial fibrillation in mice. The genes with differential ASE in poAF were enriched for myocardial structure genes, indicating the importance of atrial remodeling in the pathophysiology of AF. The greatest change in ASE between paired post-ischemic and baseline samples of the LV was in the zinc finger and homeodomain protein 2 (ZHX2) gene, a modulator of plasma lipids. Genes with differential ASE in ischemia were enriched in the ubiquitin ligase complex pathway associated with the ischemia-reperfusion response. CONCLUSIONS: Our results establish a pattern of ASE in the human heart, with a high degree of shared ASE between cardiac chambers as well as chamber-specific ASE. Furthermore, ASE analysis can be used to identify novel genes associated with (poAF) and myocardial ischemia.