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Aims: The association between microRNAs (miRNAs) and established cardiac biomarkers is largely unknown. We aimed to measure the association between plasma miRNAs and N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP), cardiac troponin I, soluble urokinase‐type plasminogen activator receptor (suPAR), and galectin‐3 with cardiac structure and function and clinical outcomes. Methods and results: We quantified 32 plasma miRNAs using the FirePlex miRNA assay and measured biomarkers in 139 individuals with symptomatic heart failure (HF). We used principal component (PC) analysis and linear regression to evaluate the association between miRNAs and biomarkers with ventricular size and function by echocardiography and Cox modelling for the incidence of a first composite event of HF hospitalization, heart transplant, left ventricular assist device implant, or death. The mean (standard deviation) age at baseline was 64.3 (12.4) years, 33 (24%) were female, and 122 (88%) were White. A total of 45 events occurred over a median follow‐up of 368 (interquartile range 234, 494) days. Baseline NT‐proBNP (β = −2.0; P = 0.001) and miRNA PC2 (β = 2.6; P = 0.002) were associated with baseline left ventricular ejection fraction. NT‐proBNP (β = 20.6; P = 0.0004), suPAR (β = −39.6; P = 0.005), and PC4 (β = 21.1; P = 0.02) were associated with baseline left ventricular end‐diastolic volumes. NT‐proBNP [hazard ratio (HR) 1.67, 95% confidence interval (CI) 1.28–2.18, P = 0.0002], galectin‐3 (HR 2.02, 95% CI 1.05–3.91, P = 0.036), PC3 (HR 1.75, 95% CI 1.23–2.49, P = 0.002), and PC4 (HR 1.67, 95% CI 1.1–2.52, P = 0.016) were independently associated with incident events. Conclusions: Biomarkers and miRNA PCs are associated with cardiac structure and function and incident cardiovascular outcomes. Combining information from miRNAs provides prognostic information beyond biomarkers in HF. [ABSTRACT FROM AUTHOR]

Mitral valve prolapse (MVP) is a common valvular disease, affecting 2–3% of the adult human population and is a degenerative condition. A total of 5–10% of the afflicted will develop severe mitral regurgitation, cardiac dysfunction, congestive heart failure, and sudden cardiac death. Naturally occurring myxomatous MVP in dogs closely resembles MVP in humans structurally, and functional consequences are similar. In both species, valvular interstitial cells (VICs) in affected valves exhibit phenotype consistent with activated myofibroblasts with increased alpha-smooth muscle actin (αSMA) expression. Using VICs collected from normal and MVP-affected valves of dogs, we analyzed the miRNA expression profile of the cells and their associated small extracellular vesicles (sEV) using RNA sequencing to understand the role of non-coding RNAs and sEV in MVP pathogenesis. miR-145 was shown to be upregulated in both the affected VICs and sEV, and overexpression of miR-145 by mimic transfection in quiescent VIC recapitulates the activated myofibroblastic phenotype. Concurrently, KLF4 expression was noted to be suppressed by miR-145, confirming the miR-145—KLF4—αSMA axis. Targeting this axis may serve as a potential therapy in controlling pathologic abnormalities found in MVP valves. [ABSTRACT FROM AUTHOR]

Background: Long‐term use of doxorubicin (DOX) is limited by cumulative dose‐dependent cardiotoxicity. Objectives: Identify plasma extracellular vesicle (EV)‐associated microRNAs (miRNAs) as a biomarker for cardiotoxicity in dogs by correlating changes with cardiac troponin I (cTnI) concentrations and, echocardiographic and histologic findings. Animals Prospective study of 9 client‐owned dogs diagnosed with sarcoma and receiving DOX single‐agent chemotherapy (total of 5 DOX treatments). Dogs with clinically relevant metastatic disease, preexisting heart disease, or breeds predisposed to cardiomyopathy were excluded. Methods: Serum concentration of cTnI was monitored before each treatment and 1 month after the treatment completion. Echocardiography was performed before treatments 1, 3, 5, and 1 month after completion. The EV‐miRNA was isolated and sequenced before treatments 1 and 3, and 1 month after completion. Results: Linear mixed model analysis for repeated measurements was used to evaluate the effect of DOX. The miR‐107 (P =.03) and miR‐146a (P =.02) were significantly downregulated whereas miR‐502 (P =.02) was upregulated. Changes in miR‐502 were significant before administration of the third chemotherapeutic dose. When stratifying miRNA expression for change in left ventricular ejection fraction, upregulation of miR‐181d was noted (P =.01). Serum concentration of cTnI changed significantly but only 1 month after treatment completion, and concentrations correlated with left ventricular ejection fraction and left ventricular internal dimension in diastole. Conclusion and Clinical Significance: Downregulation of miR‐502 was detected before significant changes in cTnI concentrations or echocardiographic parameters. Further validation using a larger sample size will be required. [ABSTRACT FROM AUTHOR]

Background: Evolving interest in comprehensively profiling the full range of small RNAs present in small tissue biopsies and in circulating biofluids, and how the profile differs with disease, has launched small RNA sequencing (RNASeq) into more frequent use. However, known biases associated with small RNASeq, compounded by low RNA inputs, have been both a significant concern and a hurdle to widespread adoption. As RNASeq is becoming a viable choice for the discovery of small RNAs in low input samples and more labs are employing it, there should be benchmark datasets to test and evaluate the performance of new sequencing protocols and operators. In a recent publication from the National Institute of Standards and Technology, Pine et al., 2018, the investigators used a commercially available set of three tissues and tested performance across labs and platforms. Results: In this paper, we further tested the performance of low RNA input in three commonly used and commercially available RNASeq library preparation kits; NEB Next, NEXTFlex, and TruSeq small RNA library preparation. We evaluated the performance of the kits at two different sites, using three different tissues (brain, liver, and placenta) with high (1 μg) and low RNA (10 ng) input from tissue samples, or 5.0, 3.0, 2.0, 1.0, 0.5, and 0.2 ml starting volumes of plasma. As there has been a lack of robust validation platforms for differentially expressed miRNAs, we also compared low input RNASeq data with their expression profiles on three different platforms (Abcam Fireplex, HTG EdgeSeq, and Qiagen miRNome). Conclusions: The concordance of RNASeq results on these three platforms was dependent on the RNA expression level; the higher the expression, the better the reproducibility. The results provide an extensive analysis of small RNASeq kit performance using low RNA input, and replication of these data on three downstream technologies. [ABSTRACT FROM AUTHOR]

Objective: Extracellular microRNAs (miRNAs) represent functional biomarkers for obesity and related disorders; this study investigated plasma miRNAs in insulin resistance phenotypes in obesity.Methods: One hundred seventy-five miRNAs were analyzed in females with obesity (insulin sensitivity, n = 11; insulin resistance, n = 19; type 2 diabetes, n = 15) and without obesity (n = 12). Correlations between miRNA level and clinical parameters and levels of 15 miRNAs in a murine obesity model were investigated.Results: One hundred six miRNAs were significantly (adjusted P ≤ 0.05) different between controls and at least one obesity phenotype, including miRNAs with the following attributes: previously reported roles in obesity and altered circulating levels (e.g., miR-122, miR-192); known roles in obesity but no reported changes in circulating levels (e.g., miR-378a); and no current reported role in, or association with, obesity (e.g., miR-28-5p, miR-374b, miR-32). The miRNAs in the latter group were found to be associated with extracellular vesicles. Forty-eight miRNAs showed significant correlations with clinical parameters; stepwise regression retained let-7b, miR-144-5p, miR-34a, and miR-532-5p in a model predictive of insulin resistance (R2  = 0.57, P = 7.5 × 10-8 ). Both miR-378a and miR-122 were perturbed in metabolically relevant tissues in a murine model of obesity.Conclusions: This study expands on the role of extracellular miRNAs in insulin-resistant phenotypes of obesity and identifies candidate miRNAs not previously associated with obesity. [ABSTRACT FROM AUTHOR]

Background/Aims: Identification of novel biomarkers to identify acute heart failure (AHF) patients at high risk of mortality is an area of unmet clinical need. Recently, we reported that the baseline level of circulating miR-30d was associated with left ventricular remodeling in response to cardiac resynchronization therapy in advanced chronic heart failure patients. However, the role of circulating miR-30d as a prognostic marker of survival in patients with AHF has not been explored. Methods: Patients clinically diagnosed with AHF were enrolled and followed up for 1 year. Quantitative reverse transcription polymerase chain reactions were used to determine serum miR-30d levels. The univariate logistic regression analysis and multivariate logistic regression analysis were used to determine the predictors for all-cause mortality in AHF patients. Kaplan-Meier survival analysis was used to analyze the role of miR- 30d in prediction of survival. Results: A total of 96 AHF patients were enrolled and followed up for 1 year. Serum miR-30d was significantly lower in AHF patients who expired in the one year follow-up period compared to those who survived. Univariate logistic regression analysis yielded 18 variables that were associated with all-cause mortality in AHF patients, while the multivariate logistic regression analysis identified 4 variables including heart rate, hemoglobin, serum sodium, and serum miR-30d level associated with mortality. ROC curve analysis showed that hemoglobin, heart rate and serum sodium displayed poor prognostic value for AHF (AUCs not higher than 0.700) compared to miR-30d level (AUC = 0.806). Kaplan-Meier survival analysis confirmed that patients with higher serum miR-30d levels had significantly lower mortality (P=0.001). Conclusion: In conclusion, this study shows evidence for the predictive value of circulating miR-30d as 1-year all-cause mortality in AHF patients. Large multicentre studies are further needed to validate our findings and accelerate the transition to clinical utilization. [ABSTRACT FROM AUTHOR]

Objective: Insulin resistance (IR) is a hallmark of obesity and metabolic disease. Circulating extracellular RNAs (ex-RNAs), stable RNA molecules in plasma, may play a role in IR, though most studies on ex-RNAs in IR are small. We sought to characterize the relationship between ex-RNAs and metabolic phenotypes in a large community-based human cohort.Research Design and Methods: We measured circulating plasma ex-RNAs in 2,317 participants without diabetes in the Framingham Heart Study (FHS) Offspring Cohort at cycle 8 and defined associations between ex-RNAs and IR (measured by circulating insulin level). We measured association between candidate ex-RNAs and markers of adiposity. Sensitivity analyses included individuals with diabetes. In a separate cohort of 90 overweight/obese youth, we measured selected ex-RNAs and metabolites. Biology of candidate microRNAs was investigated in silico.Results: The mean age of FHS participants was 65.8 years (56% female), with average BMI 27.7 kg/m2; participants in the youth cohort had a mean age of 15.5 years (60% female), with mean BMI 33.8 kg/m2. In age-, sex-, and BMI-adjusted models across 391 ex-RNAs in FHS, 18 ex-RNAs were associated with IR (of which 16 were microRNAs). miR-122 was associated with IR and regional adiposity in adults and IR in children (independent of metabolites). Pathway analysis revealed metabolic regulatory roles for miR-122, including regulation of IR pathways (AMPK, target of rapamycin signaling, and mitogen-activated protein kinase).Conclusions: These results provide translational evidence in support of an important role of ex-RNAs as novel circulating factors implicated in IR. [ABSTRACT FROM AUTHOR]

The presence and relative stability of extracellular RNAs (exRNAs) in biofluids has led to an emerging recognition of their promise as ‘liquid biopsies’ for diseases. Most prior studies on discovery of exRNAs as disease-specific biomarkers have focused on microRNAs (miRNAs) using technologies such as qRT-PCR and microarrays. The recent application of next-generation sequencing to discovery of exRNA biomarkers has revealed the presence of potential novel miRNAs as well as other RNA species such as tRNAs, snoRNAs, piRNAs and lncRNAs in biofluids. At the same time, the use of RNA sequencing for biofluids poses unique challenges, including low amounts of input RNAs, the presence of exRNAs in different compartments with varying degrees of vulnerability to isolation techniques, and the high abundance of specific RNA species (thereby limiting the sensitivity of detection of less abundant species). Moreover, discovery in human diseases often relies on archival biospecimens of varying age and limiting amounts of samples. In this study, we have tested RNA isolation methods to optimize profiling exRNAs by RNA sequencing in individuals without any known diseases. Our findings are consistent with other recent studies that detect microRNAs and ribosomal RNAs as the major exRNA species in plasma. Similar to other recent studies, we found that the landscape of biofluid microRNA transcriptome is dominated by several abundant microRNAs that appear to comprise conserved extracellular miRNAs. There is reasonable correlation of sets of conserved miRNAs across biological replicates, and even across other data sets obtained at different investigative sites. Conversely, the detection of less abundant miRNAs is far more dependent on the exact methodology of RNA isolation and profiling. This study highlights the challenges in detecting and quantifying less abundant plasma miRNAs in health and disease using RNA sequencing platforms. [ABSTRACT FROM AUTHOR]

Corresponding Author [ABSTRACT FROM AUTHOR]

Congestive heart failure (CHF) is a major cause of hospitalizations, morbidity, and mortality in Western societies. In addition to optimal medical and device therapy, exercise training is an important adjunct treatment option for CHF patients. MicroRNAs (miRNAs, miRs) participate in a variety of physiological and pathological processes. Dynamic regulation of circulating miRNAs during exercise in healthy persons and athletes has recently been documented, however, the response of circulating miRNAs to exercise in CHF patients is undetermined. Twenty-eight CHF patients underwent a symptom-limited incremental cardiopulmonary exercise test on a bicycle ergometer using a standardized exercise protocol of revised Ramp10 programs at Shanghai Tongji Hospital. Blood samples were collected before and immediately after an acute exercise session. RNA was extracted from the serum and selected miRNAs were determined using quantitative polymerase chain reactions. Moreover, inflammatory and muscle damage markers were determined by enzyme linked immunosorbent assays. We found that serum miR-21, miR-378 and miR-940 levels were significantly up-regulated immediately following an acute exercise while the rest were not changed. In addition, no robust correlation was identified between changes of these miRNAs and exercise capacity, muscle damage or inflammation. In conclusion, serum miR-21, miR-378, and miR-940 increase in response to an acute exhaustive exercise in CHF patients. Further studies are needed to clarify the potential use of circulating miRNAs as biomarkers of exercise adaptation in CHF patients, and if they have any use as prognostic markers of cardiovascular outcomes.

The release of RNA-containing extracellular vesicles (EV) into the extracellular milieu has been demonstrated in a multitude of differentin vitrocell systems and in a variety of body fluids. RNA-containing EV are in the limelight for their capacity to communicate genetically encoded messages to other cells, their suitability as candidate biomarkers for diseases, and their use as therapeutic agents. Although EV-RNA has attracted enormous interest from basic researchers, clinicians, and industry, we currently have limited knowledge on which mechanisms drive and regulate RNA incorporation into EV and on how RNA-encoded messages affect signalling processes in EV-targeted cells. Moreover, EV-RNA research faces various technical challenges, such as standardisation of EV isolation methods, optimisation of methodologies to isolate and characterise minute quantities of RNA found in EV, and development of approaches to demonstrate functional transfer of EV-RNAin vivo. These topics were discussed at the 2015 EV-RNA workshop of the International Society for Extracellular Vesicles. This position paper was written by the participants of the workshop not only to give an overview of the current state of knowledge in the field, but also to clarify that our incomplete knowledge – of the nature of EV(-RNA)s and of how to effectively and reliably study them – currently prohibits the implementation of gold standards in EV-RNA research. In addition, this paper creates awareness of possibilities and limitations of currently used strategies to investigate EV-RNA and calls for caution in interpretation of the obtained data. [ABSTRACT FROM PUBLISHER]

Background--Biomarkers that predict response to cardiac resynchronization therapy (CRT) in heart failure patients with dyssynchrony (HFDYS) would be clinically important. Circulating extracellular microRNAs (miRNAs) have emerged as novel biomarkers that may also play important functional roles, but their relevance as markers for CRT response has not been examined. Methods and Results--Comprehensive miRNA polymerase chain reaction arrays were used to assess baseline levels of 766 plasma miRNAs in patients undergoing clinically indicated CRT in an initial discovery set (n=12) with and without subsequent echocardiographic improvement at 6 months after CRT. Validation of candidate miRNAs in 61 additional patients confirmed that baseline plasma miR-30d was associated with CRT response (defined as an increase in left ventricular ejection fraction ≥10%). MiR-30d was enriched in coronary sinus blood and increased in late-contracting myocardium in a canine model of HFDYS, indicating cardiac origin with maximal expression in areas of high mechanical stress. We examined the functional effects of miR-30d in cultured cardiomyocytes and determined that miR-30d is expressed in cardiomyocytes and released in vesicles in response to mechanical stress. Overexpression of miR-30d in cultured cardiomyocytes led to cardiomyocyte growth and protected against apoptosis by targeting the mitogen-associated kinase 4, a downstream effector of tumor necrosis factor. In HFDYS patients, miR-30d plasma levels inversely correlated with high-sensitivity troponin T, a marker of myocardial necrosis. Conclusions--Baseline plasma miR-30d level is associated with response to CRT in HFDYS in this translational pilot study. MiR- 30d increase in cardiomyocytes correlates with areas of increased wall stress in HFDYS and is protective against deleterious tumor necrosis factor signaling. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Circulating MicroRNA-30d Is Associated With Response to Cardiac Resynchronization Therapy in Heart Failure and Regulates Cardiomyocyte Apoptosis: A Translational Pilot Study" by Y.F. Melman along with the author's response to the same.

Introduction: The risk of rejection after pediatric heart transplantation remains a major clinical concern. Candidate miRNAs for acute rejection were recently identified among adults, but haven't been validated yet in children after heart transplantation (HT). Hypothesis: Pediatric heart recipients with biopsy-proven acute rejection have dynamic changes in their plasma miRNA profiles compared to their own nonrejection baseline. Methods: We prospectively assessed miRNA expression in 22 recipients with median age at HT 12 yrs (0.3-17) between 3/2013 and 2/2017. Serial blood samples were collected on routine biopsy day and frozen as plasma. All patients had miRNAs profiled at nonrejection baseline (BL) and at subsequent follow-up. Biopsy-proven rejection was defined as acute cellular rejection (ACR) Grade ≥2R or antibody mediated rejection (AMR) (ISHLT-2004). We assessed circulating miRNAs using Next-Generation RNAseq in the discovery cohort of 5 recipients' plasma (3 ACR and 2 nonrejection). A panel including the top 22 miRNAs (13 from RNAseq discovery and 9 from literature) was created using the FirePlex platform and validated in the remaining 17 recipients (9 ACR, 4 AMR, 4 nonrejection). We assessed differential expression using paired T-test. Results: Median time from HT to first BL biopsy-sample was 140 days (11-38) and from BL to subsequent follow-up 91 days (11-510). RNAseg revealed 17 differentially expressed, non-overlapping miRNAs in 3 recipients with acute rejection compared with differentially expressed miRNAs in 2 recipients with nonrejection follow-up (nominal P < 0.05). In these 2 recipients with nonrejection follow-up, 13 miRNAs were differently expressed when compared with BL and nonrejection follow-up (nominal P<0.05). The FirePlex platform validation in 13 recipients with acute rejection revealed differentially expressed miR-92a-3p, 10a-5p and 27a-3p in their plasma miRNA profiles compared to their own nonrejection BL (nominal P-value < 0.05). In these 13 patients, plasma miR-92a was reduced 0.579 log-fold, remaining significant after adjustment for multiple comparisons (P = 0.03). Conclusions: Circulating miRNAs are dynamically regulated during rejection in children after HT, and the profile of these regulated miRNAs may be different from adults. The miR-92a may have value as a noninvasive marker for acute rejection after validation in large pediatric heart recipient's cohort. [ABSTRACT FROM AUTHOR]