Circulating miRNAs reflect early myocardial injury and recovery after heart transplantation

Amplification of Plasma MicroRNAs for Non-invasive Early Detection of Acute Rejection after Heart Transplantation With Ultrasound-Targeted Microbubble Destruction

OBJECTIVE

Acute rejection (AR) screening has always been the focus of patient management in the first several years after heart transplantation (HT). As potential biomarkers for the non-invasive diagnosis of AR, microRNAs (miRNAs) are limited by their low abundance and complex origin. Ultrasound-targeted microbubble destruction (UTMD) technique could temporarily alter vascular permeability through cavitation. We hypothesized that increasing the permeability of myocardial vessels might enhance the abundance of circulating AR-related miRNAs, thus enabling the non-invasive monitoring of AR.

METHODS

The Evans blue assay was applied to determine efficient UTMD parameters. Blood biochemistry and echocardiographic indicators were used to ensure the safety of the UTMD. AR of the HT model was constructed using Brown-Norway and Lewis rats. Grafted hearts were sonicated with UTMD on postoperative day (POD) 3. The polymerase chain reaction was used to identify upregulated miRNA biomarkers in graft tissues and their relative amounts in the blood.

RESULTS

Amounts of six kinds of plasma miRNA, including miR-142-3p, miR-181a-5p, miR-326-3p, miR-182, miR-155-5p and miR-223-3p, were 10.89 ± 1.36, 13.54 ± 2.15, 9.84 ± 0.70, 8.55 ± 2.00, 12.50 ± 3.96 and 11.02 ± 3.47 times higher in the UTMD group than those in the control group on POD 3. Plasma miRNA abundance in the allograft group without UTMD did not differ from that in the isograft group on POD 3. After FK506 treatment, no miRNAs increased in the plasma after UTMD.

CONCLUSION

UTMD can promote the transfer of AR-related miRNAs from grafted heart tissue to the blood, allowing non-invasive early detection of AR.

Novel Soluble Mediators of Innate Immune System Activation in Solid Allograft Rejection

During the past years, solid allograft rejection has been considered the consequence of either cellular- or antibody-mediated reaction both being part of the adaptive immune response, whereas the role of innate immunity has been mostly considered less relevant. Recently, a large body of evidence suggested that the innate immune response and its soluble mediators may play a more important role during solid allograft rejection than originally thought. This review will highlight the role of novel soluble mediators that are involved in the activation of innate immunity during alloimmune response and solid allograft rejection. We will also discuss emerging strategies to alleviate the aforementioned events. Hence, novel, feasible, and safe clinical therapies are needed to prevent allograft loss in solid organ transplantation. Fully understanding the role of soluble mediators of innate immune system activation may help to mitigate solid allograft rejection and improve transplanted recipients' outcomes.

Biomarkers in the clinical management of patients with atrial fibrillation and heart failure

Atrial fibrillation (AF) and heart failure (HF) are two cardiovascular diseases with an increasing prevalence worldwide. These conditions share common pathophysiologiesand frequently co-exit. In fact, the occurrence of either condition can 'cause' the development of the other, creating a new patient group that demands different management strategies to that if they occur in isolation. Regardless of the temproral association of the two conditions, their presence is linked with adverse cardiovascular outcomes, increased rate of hospitalizations, and increased economic burden on healthcare systems. The use of low-cost, easily accessible and applicable biomarkers may hasten the correct diagnosis and the effective treatment of AF and HF. Both AF and HF effect multiple physiological pathways and thus a great number of biomarkers can be measured that potentially give the clinician important diagnostic and prognostic information. These will then guide patient centred therapeutic management. The current biomarkers that offer potential for guiding therapy, focus on the physiological pathways of miRNA, myocardial stretch and injury, oxidative stress, inflammation, fibrosis, coagulation and renal impairment. Each of these has different utility in current clinincal practice.

Role of Micro RNA in Heart Transplant

The need for non-invasive biomarkers for diagnostic, prognostic, and therapeutic purposes is increasingly being recognized in the field of heart transplantation. MicroRNAs are a class of novel biomarkers that control gene expression and influence cellular functions, including differentiation, proliferation and functional regulation of the immune system. They can be detected in the serum, plasma, and urine, and may serve as early noninvasive biomarkers for various disease processes. Despite significant advances in heart transplantation, challenges remain in the short and long term with early graft injury and dysfunction, both cellular and antibody mediated rejection, infections of varying types and severity, and cardiac allograft vasculopathy, which require an interventional approach for diagnosis and management. In this article, we review the current knowledge on the role of microRNAs in heart transplantation and its related complications, and discuss their potential impact in future strategies to manage heart transplantation.

MicroRNAs as theranostic markers in cardiac allograft transplantation: from murine models to clinical practice

Congestive heart failure affects about 23 million people worldwide, and cardiac allograft transplantation remains one of the last options for patients with terminal refractory heart failure. Besides the infectious or oncological complications, the prognosis of patients after heart transplantation is affected by acute cellular or antibody-mediated rejection and allograft vasculopathy development. Current monitoring of both conditions requires the performance of invasive procedures (endomyocardial biopsy sampling and coronary angiography or optical coherence tomography, respectively) that are costly, time-demanding, and non-comfortable for the patient. Within this narrative review, we focus on the potential pathophysiological and clinical roles of microRNAs (miRNAs, miRs) in the field of cardiac allograft transplantation. Firstly, we provide a general introduction about the status of cardiac allograft function monitoring and the discovery of miRNAs as post-transcriptional regulators of gene expression and clinically relevant biomarkers found in the extracellular fluid. After this general introduction, information from animal and human studies are summarized to underline the importance of miRNAs both in the pathophysiology of the rejection process, the possibility of its modulation by altering miRNAs levels, and last but not least, about the use of miRNAs in the clinical practice to diagnose or predict the rejection occurrence.

The evolution of patient-specific precision biomarkers to guide personalized heart-transplant care

Introduction

In parallel to the clinical maturation of heart transplantation over the last 50 years, rejection testing has been revolutionized within the systems biology paradigm triggered by the Human Genome Project.

Areas Covered

We have co-developed the first FDA-cleared diagnostic and prognostic leukocyte gene expression profiling biomarker test in transplantation medicine that gained international evidence-based medicine guideline acceptance to rule out moderate/severe acute cellular cardiac allograft rejection without invasive endomyocardial biopsies. This work prompted molecular re-classification of intragraft biology, culminating in the identification of a pattern of intragraft myocyte injury, in addition to acute cellular rejection and antibody-mediated rejection. This insight stimulated research into non-invasive detection of myocardial allograft injury. The addition of a donor-organ specific myocardial injury marker based on donor-derived cell-free DNA further strengthens the non-invasive monitoring concept, combining the clinical use of two complementary non-invasive blood-based measures, host immune activity-related risk of acute rejection as well as cardiac allograft injury.

Expert Opinion

This novel complementary non-invasive heart transplant monitoring strategy based on leukocyte gene expression profiling and donor-derived cell-free DNA that incorporates longitudinal variability measures provides an exciting novel algorithm of heart transplant allograft monitoring. This algorithm's clinical utility will need to be tested in an appropriately designed randomized clinical trial which is in preparation.

Noninvasive biomarkers for prediction and diagnosis of heart transplantation rejection

For most patients with end-stage heart failure, heart transplantation is the treatment of choice. Allograft rejection is one of the major post-transplantation complications affecting graft outcome and survival. Recent advancements in science and technology offer an opportunity to integrate genomic and other omics-based biomarkers into clinical practice, facilitating noninvasive evaluation of allograft for diagnostic and prognostic purposes. Omics, including gene expression profiling (GEP) of blood immune cell components and donor-derived cell-free DNA (dd-cfDNA) are of special interest to researchers. Several studies have investigated levels of dd-cfDNA and miroRNAs in blood as potential markers for early detection of allograft rejection. One of the achievements in the field of transcriptomics is AlloMap, GEP of peripheral blood mononuclear cells (PBMC), which can identify 11 differentially expressed genes and help with detection of moderate and severe acute cellular rejection in stable heart transplant recipients. In recent years, the utilization of GEP of PBMC for identifying differentially expressed genes to diagnose acute antibody-mediated rejection and cardiac allograft vasculopathy has yielded promising results. Advancements in the field of metabolomics and proteomics as well as their potential implications have been further discussed in this paper.

MicroRNA profiling as a novel diagnostic tool for identification of patients with inflammatory and/or virally induced cardiomyopathies

AIMS

MicroRNAs (miRNAs) might be used as prospective biomarkers for the identification of unexplained heart failure caused by a viral and/or inflammatory process. The aim of this study was to identify and to evaluate prognostic miRNAs in serum of patients with inflammatory heart diseases diagnosed by endomyocardial biopsies.

METHODS AND RESULTS

After TaqMan® OpenArray® screening of 754 unique circulating miRNAs in serum of biopsy-proven patients [184 patients with inflammatory and/or virally induced myocardial diseases (DCMi), 25 patients with dilated cardiomyopathy (DCM), and 25 healthy donors], we identified seven miRNAs of interest (P < 0.05). These data have been verified by single qRT-PCR assays in other biopsy-proven patients (159 patients with viral and/or inflammatory myocardial diseases, 46 patients with DCM, and 60 healthy donors). The expression of let-7f, miR-197, miR-223, miR-93, and miR-379 allowed us to differentiate between patients with a virus and/or inflammation and healthy donors (P < 0.05) with the specificity over 93%. Based on the expression of miR-21 and miR-30a-5p, we could sort out patients with DCM from all other study groups (P < 0.05) with the specificity over 95%.

CONCLUSIONS

This miRNA profile provides for the first time a new non-invasive diagnostic perspective to identify patients with intramyocardial inflammation and/or viral persistence only from single serum sample, independently of prescribed therapy and time of symptoms onset. It allows the early finding of those patients relevant for myocardial biopsy for exact diagnosis and further proscription of causal aetiology-driven specific treatment.

MicroRNAs in solid organ and vascularized composite allotransplantation: Potential biomarkers for diagnosis and therapeutic use

Nowadays, solid organ transplantation (SOT) is an established treatment for patients with end-organ dysfunction, which dramatically improves the quality-of-life. Vascularized composite allotransplants (VCAs) including hand and face have been reported worldwide over the last 20 years. However, VCAs, differently to SOT, are life-enhancing instead of life-saving and are not routinely performed due to the risk of immune rejection and the adverse effects of immunosuppression. Over the past decade, although considerable improvements in short-term outcomes after allotransplantation have been registered, these results have not been translated into major progress in long-term allograft acceptance and patient survival. Recently active researches in the field of biomarker discovery have been conducted to develop individualized therapies for allograft recipients. MicroRNAs (miRNAs) are a small noncoding RNAs functioning as critical regulators of gene and protein expression by RNA interference. They have been connected in numerous biological processes and diseases. Due to their immunomodulatory functions, miRNAs have been amended as potential diagnostic and prognostic biomarker for the detection of rejection in allotransplantation. Due to their specific circulating expression profile, they could act as noninvasive predictive tools for rejection that may help clinicians in an early adjustment of the immunosuppression protocol during acute rejections episodes. Indeed, specific anti-sense oligonucleotides suppressing miRNAs expressed in rejection could reduce the rejection rate in allografts and decrease the use of immunosuppressants. We present a literature review of the immunomodulatory properties and characteristics of miRNAs. We will summarize the current knowledge on miRNAs as potential biomarkers for allograft rejection and possible application in allotransplantation monitoring. Finally, we will discuss the advances in preclinical miRNA-based therapies for immunosuppression.

RETRACTED: MicroRNA-208-5p regulates myocardial injury of sepsis mice via targeting SOCS2-mediated NF-κB/HIF-1α pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figures 6E and 7E, and suspected image duplications within Figures 1B, 4A and 5B, as detailed here: https://pubpeer.com/publications/782E18F3418A54CBE4DB7FFAA5735F; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Additional suspected image duplications were detected in Figures 1C and 6A. Our analysis suggested these image anomalies represent either direct duplications of the entire image, or contain several repeated features between or within an image. The journal requested the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Circulatory miR-133b and miR-21 as Novel Biomarkers in Early Prediction and Diagnosis of Coronary Artery Disease

While coronary artery disease (CAD) has become a major threat worldwide, the timely biomarker-based early diagnosis of CAD remains a major unmet clinical challenge. We aimed towards assessing the level of circulatory microRNAs as candidates of novel biomarkers in patients with CAD. A total of 147 subjects were recruited which includes 78 subjects with angiographically proven CAD, 15 pre-atherosclerotic normal coronary artery (NCA) subjects and 54 healthy individuals. Quantitative real-time PCR assays were performed. MiR-133b was downregulated by 4.6 fold (p < 0.0001) whereas miR-21 was upregulated by ~2 fold (p < 0.0001) in plasma samples of CAD patients. Importantly, both the miRNAs showed association with disease severity as miR-133b was downregulated by 8.45 fold in acute coronary syndrome (ACS), 3.38 fold in Stable angina (SA) and 2.08 fold in NCA. MiR-21 was upregulated by 2.46 fold in ACS, 1.90 fold in SA and 1.12 fold in NCA. Moreover, miR-133b could significantly differentiate subjects with ST-elevation myocardial infarction (STEMI) from Non-STEMI. Area under the curve (AUC) for miR-133b was 0.80 with >75.6% sensitivity and specificity, AUC for miR-21 was 0.79 with >69.4% sensitivity and specificity. Our results suggest that miR-133b and miR-21 could be possible candidates of novel biomarkers in early prediction of CAD.

MiRNA-208a as a Sensitive Early Biomarker for the Postoperative Course Following Congenital Heart Defect Surgery

Current clinical risk assessment strategies have poor accuracy for identifying patients who will suffer adverse perioperative events. There is an ongoing need to integrate clinical variables with novel technology and biomarkers to accurately predict outcome after pediatric heart surgery. We tested the hypothesis that miRNAs-208a, -208b, and -499 can serve as noninvasive biomarkers for the extent of myocardial damage and the postoperative clinical course of pediatric patients with congenital heart defects (CHDs) at an early time point following surgery. Serum samples were obtained from 79 pediatric patients before and 6, 12, and 24 h after surgery. MiRNAs-208a, -208b, and -499 were quantified by RQ-PCR. Correlations between the patient's clinical variables and miRNA levels were tested. Our results show that the levels of the three miRNAs were elevated at 6 h after surgery, remained high at 12 h and declined at 24 h after the operation. The amount of all three miRNAs at 6 h after surgery correlated with surgical and laboratory parameters. Their amount at 12 h after surgery correlated with the length of stay at the hospital. Expression levels of miRNA-208a at 6 h were related to the appearance of cardiac complications, and could predict whether a patient will sustain complications or will be ventilated for more than 48 h after surgery. Circulating miRNA-208a is a predictor for the risk of developing cardiac complications during the postoperative course as early as 6 h after heart surgery for CHD in pediatric patients.

Regulation of miR-29b and miR-30c by vitamin D receptor activators contributes to attenuate uraemia-induced cardiac fibrosis

Background

Uraemic cardiomyopathy, a process mainly associated with increased myocardial fibrosis, is the leading cause of death in chronic kidney disease patients and can be prevented by vitamin D receptor activators (VDRAs). Since some microRNAs (miRNAs) have emerged as regulators of the fibrotic process, we aimed to analyse the role of specific miRNAs in VDRA prevention of myocardial fibrosis as well as their potential use as biomarkers.

Methods

Wistar rats were nephrectomized and treated intraperitoneally with equivalent doses of two VDRAs: calcitriol and paricalcitol. Biochemical parameters, cardiac fibrosis, miRNA (miR-29b, miR-30c and miR-133b) levels in the heart and serum and expression of their target genes collagen I (COL1A1), matrix metalloproteinase 2 (MMP-2) and connective tissue growth factor (CTGF) in the heart were evaluated.

Results

Both VDRAs attenuated cardiac fibrosis, achieving a statistically significant difference in the paricalcitol-treated group. Increases in RNA and protein levels of COL1A1, MMP-2 and CTGF and reduced expression of miR-29b and miR-30c, known regulators of these pro-fibrotic genes, were observed in the heart of chronic renal failure (CRF) rats and were attenuated by both VDRAs. In serum, significant increases in miR-29b, miR-30c and miR-133b levels were observed in CRF rats, which were prevented by VDRA use. Moreover, vitamin D response elements were identified in the three miRNA promoters.

Conclusions

VDRAs, particularly paricalcitol, attenuated cardiac fibrosis acting on COL1A1, MMP-2 and CTGF expression, partly through regulation of miR-29b and miR-30c. These miRNAs and miR-133b could be useful serum biomarkers for cardiac fibrosis and also potential new therapeutic targets.

Circulating miR-1 as a potential biomarker of doxorubicin-induced cardiotoxicity in breast cancer patients

Cardiotoxicity is associated with the chronic use of doxorubicin leading to cardiomyopathy and heart failure. Identification of cardiotoxicity-specific miRNA biomarkers could provide clinicians with a valuable prognostic tool. The aim of the study was to evaluate circulating levels of miRNAs in breast cancer patients receiving doxorubicin treatment and to correlate with cardiac function. This is an ancillary study from “Carvedilol Effect on Chemotherapy-induced Cardiotoxicity” (CECCY trial), which included 56 female patients (49.9±3.3 years of age) from the placebo arm. Enrolled patients were treated with doxorubicin followed by taxanes. cTnI, LVEF, and miRNAs were measured periodically. Circulating levels of miR-1, -133b, -146a, and -423-5p increased during the treatment whereas miR-208a and -208b were undetectable. cTnI increased from 6.6±0.3 to 46.7±5.5 pg/mL (p<0.001), while overall LVEF tended to decrease from 65.3±0.5 to 63.8±0.9 (p=0.053) over 12 months. Ten patients (17.9%) developed cardiotoxicity showing a decrease in LVEF from 67.2±1.0 to 58.8±2.7 (p=0.005). miR-1 was associated with changes in LVEF (r=-0.531, p<0.001). In a ROC curve analysis miR-1 showed an AUC greater than cTnI to discriminate between patients who did and did not develop cardiotoxicity (AUC = 0.851 and 0.544, p= 0.0016). Our data suggest that circulating miR-1 might be a potential new biomarker of doxorubicin-induced cardiotoxicity in breast cancer patients.

Regulatory RNAs and cardiovascular disease - with a special focus on circulating microRNAs

MicroRNAs (miRNAs) are a class of short non-coding regulatory RNA molecules which play an important role in intracellular communication and cell signaling and which influence cellular processes such as proliferation, differentiation, and cellular death. Over the past two decades, the crucial role of microRNAs in controlling tissue homeostasis and disease in cardiovascular systems has become widely recognized. By controlling the expression levels of their targets, several miRNAs have been shown to modulate the function of endothelial cells (miR-221/222 and -126), vascular smooth muscle cells (miR-143/145) and macrophages (miR-33, -758, and -26), thereby regulating the development and progression of atherosclerosis. The stability of miRNAs within the blood suggests that circulating miRNAs may function as important biomarkers of disease development and progression. Numerous circulating miRNAs have been found to be dysregulated in a wide variety of different disease states, including diabetes, cancer, and cardiovascular disease.

Modulating microRNAs in cardiac surgery patients: Novel therapeutic opportunities?

This review focuses on microRNAs (miRs) in cardiac surgery, where they are emerging as potential targets for therapeutic intervention as well as novel clinical biomarkers. Identification of the up/down-regulation of specific miRs in defined groups of cardiac surgery patients can lead to the development of novel strategies for targeted treatment in order to maximise therapeutic results and minimise acute, delayed or chronic complications. MiRs could also be involved in determining the outcome independently of complications, for example in relation to myocardial perfusion and fibrosis. Because of their relevance in disease, their known sequence and pharmacological properties, miRs are attractive candidates for therapeutic manipulation. Pharmacological inhibition of individual miRs can be achieved by modified antisense oligonucleotides, referred to as antimiRs, while miR replacement can be achieved by miR mimics to increase the level of a specific miR. MiR mimics can restore the function of a lost or down-regulated miR, while antimiRs can inhibit the levels of disease-driving or aberrantly expressed miRs, thus de-repressing the expression of mRNAs targeted by the miR. The main delivery methods for miR therapeutics involve lipid-based vehicles, viral systems, cationic polymers, and intravenous or local injection of an antagomiR. Local delivery is particularly desirable for miR therapeutics and options include the development of devices specific for local delivery, light-induced antimiR, and vesicle-encapsulated miRs serving as therapeutic delivery agents able to improve intracellular uptake. Here, we discuss the potential therapeutic use of miRNAs in the context of cardiac surgery.

Prospective and therapeutic screening value of non-coding RNA as biomarkers in cardiovascular disease

Non-coding RNA (ncRNA) is a class of genetic, epigenetic and translational regulators, containing short and long transcripts with intriguing abilities for use as biomarkers due to their superordinate role in disease development. In the past five years many of these have been investigated in cardiovascular diseases (CVD), mainly myocardial infarction (MI) and heart failure. To extend this view, we summarize the existing data about ncRNA as biomarker in the whole entity of CVDs by literature-based review and comparison of the identified candidates. The myomirs miRNA-1, -133a/b, -208a, -499 with well-defined cellular functions have proven equal to classic protein biomarkers for disease detection in MI. Other microRNAs (miRNAs) were reproducibly found to correlate with disease, disease severity and outcome in heart failure, stroke, coronary artery disease (CAD) and aortic aneurysm. An additional utilization has been discovered for therapeutic monitoring. The function of long non-coding transcripts is only about to be unraveled, yet shows great potential for outcome prediction. ncRNA biomarkers have a distinct role if no alternative test is available or has is performing poorly. With increasing mechanistic understanding, circulating miRNA and long non-coding transcripts will provide useful disease information with high predictive power.

Micro-RNA-208a, -208b, and -499 as Biomarkers for Myocardial Damage After Cardiac Surgery in Children

OBJECTIVES

To test the hypothesis that cardiac-enriched micro-RNAs can serve as accurate biomarkers that reflect myocardial injury and to predict the postoperative course following pediatric cardiac surgery. Micro-RNAs have emerged as plasma biomarkers for many pathologic states. We aimed to quantify preoperative and postoperative plasma levels of cardiac-enriched micro-RNA-208a, -208b, and -499 in children undergoing cardiac surgery and to evaluate correlations between their levels, the extent of myocardial damage, and the postoperative clinical course.

DESIGN

PICU.

PATIENTS

Thirty pediatric patients that underwent open heart surgery for the correction of congenital heart defects between January 2012 to July 2013.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

At 12 hours post surgery, the plasma levels of the micro-RNAs increased by 300- to 4,000-fold. At 24 hours, their levels decreased but remained significantly higher than before surgery. Micro-RNA levels were associated with troponin levels, longer cardiopulmonary bypass and aortic crossclamp times, maximal postoperative aspartate aminotransferase levels, and delayed hospital discharge.

CONCLUSIONS

Circulating micro-RNA-208a, -208b, and -499 are detectable in the plasma of children undergoing cardiac surgery and may serve as novel biomarkers for monitoring and forecasting postoperative myocardial injury and recovery.

Circulating microRNA profile in patients with membranous obstruction of the inferior vena cava

Membranous obstruction of the inferior vena cava (MOVC) is a common type of Budd-Chiari syndrome. However, the pathogenesis of MOVC has not been fully elucidated. Recent studies demonstrated that microRNAs (miRNAs or miRs) are involved in multiple diseases. To the best of our knowledge, specific changes in the expression of miRNAs in MOVC patients have not been previously assessed. The present study used a microarray analysis, followed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) validation, with the aim to access the miRNA expression levels in the plasma of 34 MOVC patients, compared with those in healthy controls. The results revealed a total of 16 differentially expressed miRNAs in MOVC patients. Subsequently, RT-qPCR analysis verified the statistically consistent expression of 5 selected miRNAs (miR-125a-5p, miR-133b, miR-423-5p, miR-1228-5p and miR-1266), in line with the results of the microarray analysis. These 5 miRNAs, which were described as crucial regulators in numerous biological processes and vascular diseases, may play an important role in the pathogenesis of MOVC. Bioinformatics analysis of target genes of the differentially expressed miRNAs revealed that these predicted targets were significantly enriched and involved in several key signaling pathways important for MOVC, including the ErbB, Wnt, MAPK and VEGF signaling pathway. In conclusion, miRNAs may involve in multiple signaling pathways contributing to the pathological processes of MOVC. The present study offers an intriguing new perspective on the involvement of miRNAs in MOVC; however, the precise underlying mechanisms require further validation.

Interaction between microRNA expression and classical risk factors in the risk of coronary heart disease

The aim of this study was to identify the synergistic effect of microRNA expression with classical risk factors of coronary heart disease (CHD) and to explore their diagnostic value for coronary stenotic lesions in subjects with CHD. Plasma samples were obtained from 66 subjects with CHD and from 58 control individuals. A quantitative reverse-transcription PCR (RT-qPCR) assay was conducted to confirm the relative expressions of the known CHD-related miRNAs. The severity of coronary atherosclerosis was based on the Gensini scoring system. The expression of miR-125b in plasma of the CHD group was lower than that of the non-CHD group (0.14 ± 0.09 vs. 0.18 ± 0.10, p = 0.055), and the miR-125b levels significantly decreased following an increasing Gensini score (P = 0.037). Spearman correlation analyses indicated the Gensini score was negatively associated with miR-125b (r = −0.215, p = 0.017). Of all the miRNAs, miR-125b showed the lowest AUC (0.405; 95% CI: 0.305 ~ 0.506, p = 0.070). We found several synergistic effects between miR-125b and classical risk factors, such as age, sex, CR, FBG and HDL-C; the proportion of CHD attributable to the interaction of miR-125b and age was as high as 80%. Therefore, miR-125b was shown to play an important role in individual’s susceptibility to developing CHD.

The biology of circulating microRNAs in cardiovascular disease

BACKGROUND

Since their first description in mammalian cells, more than 2500 microRNA molecules have been predicted or verified within human cells. Recently, extracellular microRNAs have been described, protected from degradation by specialized packaging in extracellular vesicles or RNA-binding proteins.

MATERIALS AND METHODS

We will discuss recent data regarding circulating microRNAs, their potential role as novel biomarkers and intercellular communicators, as well as future challenges of studying and applying such novel biology, particularly in the cardiovascular system.

RESULTS

Circulating microRNAs have been proposed as attractive candidates as both diagnostic and prognostic biomarkers in various diseases, including a spectrum of cardiovascular conditions. Moreover, consistent with our evolving appreciation of the role of exosomes and microvesicles in intercellular communication, it has been proposed that delivery of active microRNAs to recipient tissues may serve as a primary mode of intercellular communication. Indeed, the transfer of functional microRNAs has been demonstrated in in vitro models and has been reported in a few in vivo contexts. In addition, therapeutic application of extracellular microRNAs has also been explored.

CONCLUSION

Over recent years, increasing attention has been paid to the role of circulating miRNAs in cardiovascular disease. As biomarkers and intercellular communicators, circulating miRNAs could play important roles in the prediction, diagnosis and tailored treatment of cardiovascular diseases in the near future.

Assay reproducibility in clinical studies of plasma miRNA

There are increasing reports of plasma miRNAs as biomarkers of human disease but few standards in methodologic reporting, leading to inconsistent data. We systematically reviewed plasma miRNA studies published between July 2013-June 2014 to assess methodology. Six parameters were investigated: time to plasma extraction, methods of RNA extraction, type of miRNA, quantification, cycle threshold (Ct) setting, and methods of statistical analysis. We compared these data with a proposed standard methodologic technique. Beginning with initial screening for 380 miRNAs using microfluidic array technology and validation in an additional cohort of patients, we compared 11 miRNAs that exhibited differential expression between 16 patients with benign colorectal neoplasms (advanced adenomas) and 16 patients without any neoplasm (controls). Plasma was isolated immediately, 12, 24, 48, or 72 h following phlebotomy. miRNA was extracted using two different techniques (Trizol LS with pre-amplification or modified miRNeasy). We performed Taqman-based RT-PCR assays for the 11 miRNAs with subsequent analyses using a variable Ct setting or a fixed Ct set at 0.01, 0.03, 0.05, or 0.5. Assays were performed in duplicate by two different operators. RNU6 was the internal reference. Systematic review yielded 74 manuscripts meeting inclusion criteria. One manuscript (1.4%) documented all 6 methodological parameters, while < 5% of studies listed Ct setting. In our proposed standard technique, plasma extraction ≤12 h provided consistent ΔCt. miRNeasy extraction yielded higher miRNA concentrations and fewer non-expressed miRNAs compared to Trizol LS (1/704 miRNAs [0.14%] vs 109/704 miRNAs [15%], not expressed, respectively). A fixed Ct bar setting of 0.03 yielded the most reproducible data, provided that <10% miRNA were non-expressed. There was no significant intra-operator variability. There was significant inter-operator variation using Trizol LS extraction, while this was negligible using modified miRNeasy. For standardized reporting, we recommend plasma extraction ≤ 12 h, using modified miRNeasy extraction and utilizing a 0.03 Ct.

Expression of Plasma microRNA-1/21/ 208a/499 in Myocardial Ischemic Reperfusion Injury

Objectives: We aimed to measure changes in the levels of several miRNAs during open-heart surgery and to investigate the relationship between these changes and cardiac biomarkers. Methods: Creatine kinase-muscle band (CK-MB), cardiac troponin (cTnI) and miRNA (miR-1/21/208a/499) levels were measured during open-heart surgery in 15 patients undergoing combined mitral and aortic valve replacement. The levels of these markers were measured presurgically, 45 min after aortic clamping, 60 min after reperfusion and 24 h after surgery. Results: Significant differences were found in miR-1/208a/499 levels but not in miR-21 levels. miR-1/208a levels were unchanged until 45 min after aortic clamping, increased 60 min after reperfusion (p < 0.001) and decreased significantly 24 h after surgery (p < 0.001). The changes in miR-1/208a levels exhibited a similar pattern to those observed for cTnI and CK-MB, although the changes in miR-208a levels reflected more rapidly than those in miR-1 levels. miR-499 levels decreased after reperfusion (p < 0.001) until 24 h after surgery; these levels were negatively correlated with cTnI and CK-MB levels at all of the time points. Conclusions: A time-dependent change in miR-1/208a/499 levels occurred during open-heart surgery, and these were associated with levels of cTnI and CK-MB. These results reveal that miRNAs may be sensitive biomarkers for I/R injury during open-heart surgery.

Noncoding RNAs and myocardial fibrosis

Cardiac stress leads to remodelling of cardiac tissue, which often progresses to heart failure and death. Part of the remodelling process is the formation of fibrotic tissue, which is caused by exaggerated activity of cardiac fibroblasts leading to excessive extracellular matrix production within the myocardium. Noncoding RNAs (ncRNAs) are a diverse group of endogenous RNA-based molecules, which include short (∼22 nucleotides) microRNAs and long ncRNAs (of >200 nucleotides). These ncRNAs can regulate important functions in many cardiovascular cells types. This Review focuses on the role of ncRNAs in cardiac fibrosis; specifically, ncRNAs as therapeutic targets, factors for direct fibroblast transdifferentation, their use as diagnostic and prognostic markers, and their potential to function as paracrine modulators of cardiac fibrosis and remodelling.

Design and Analysis for Studying microRNAs in Human Disease: A Primer on -Omic Technologies

microRNAs (miRNAs) are fundamental to cellular biology. Although only approximately 22 bases long, miRNAs regulate complex processes in health and disease, including human cancer. Because miRNAs are highly stable in circulation when compared with several other classes of nucleic acids, they have generated intense interest as clinical biomarkers in diverse epidemiologic studies. As with other molecular biomarker fields, however, miRNA research has become beleaguered by pitfalls related to terminology and classification; procedural, assay, and study cohort heterogeneity; and methodological inconsistencies. Together, these issues have led to both false-positive and potentially false-negative miRNA associations. In this review, we summarize the biological rationale for studying miRNAs in human disease with a specific focus on circulating miRNAs, which highlight some of the most challenging topics in the field to date. Examples from lung cancer are used to illustrate the potential utility and some of the pitfalls in contemporary miRNA research. Although the field is in its infancy, several important lessons have been learned relating to cohort development, sample preparation, and statistical analysis that should be considered for future studies. The goal of this primer is to equip epidemiologists and clinical researchers with sound principles of study design and analysis when using miRNAs.

Computational prediction of disease microRNAs in domestic animals

BACKGROUND

The most important means of identifying diseases before symptoms appear is through the discovery of disease-associated biomarkers. Recently, microRNAs (miRNAs) have become highly useful biomarkers of infectious, genetic and metabolic diseases in human but they have not been well studied in domestic animals. It is probable that many of the animal homologs of human disease-associated miRNAs may be involved in domestic animal diseases. Here we describe a computational biology study in which human disease miRNAs were utilized to predict orthologous miRNAs in cow, chicken, pig, horse, and dog.

RESULTS

We identified 287 human disease-associated miRNAs which had at least one 100% identical animal homolog. The 287 miRNAs were associated with 359 human diseases referenced in 2,863 Pubmed articles. Multiple sequence analysis indicated that over 60% of known horse mature miRNAs found perfect matches in human disease-associated miRNAs, followed by dog (50%). As expected, chicken had the least number of perfect matches (5%). Phylogenetic analysis of miRNA precursors indicated that 85% of human disease pre-miRNAs were highly conserved in animals, showing less than 5% nucleotide substitution rates over evolutionary time. As an example we demonstrated conservation of human hsa-miR-143-3p which is associated with type 2 diabetes and targets AKT1 gene which is highly conserved in pig, horse and dog. Functional analysis of AKT1 gene using Gene Ontology (GO) showed that it is involved in glucose homeostasis, positive regulation of glucose import, positive regulation of glycogen biosynthetic process, glucose transport and response to food.

CONCLUSIONS

This data provides the animal and veterinary research community with a resource to assist in generating hypothesis-driven research for discovering animal disease-related miRNA from their datasets and expedite development of prophylactic and disease-treatment strategies and also influence research efforts to identify novel disease models in large animals. Integrated data is available for download at http://agbase.hpc.msstate.edu/cgi-bin/animal_mirna.cgi.

Peripheral blood miRNAs as a biomarker for chronic cardiovascular diseases

Vascular diseases are the most prevalent diseases worldwide. This study intended to analyze peripheral blood miRNA levels and their correlation with NT-pro-BNP and cTN-I in patients with atherosclerosis or pre-atherosclerotic conditions to build a dynamic correlation between vascular diseases and their biomarkers. Serum NT-pro-BNP and cTN-I levels were measured by their respective ELISA kits. The miRNA levels were assayed by quantitative PCR. Unique miRNA signatures were identified for both atherosclerosis and pre-atherosclerosis. The levels of miR-92a, 126, 130a, 222, and 370 levels were decreased in the peripheral blood of pre-atherosclerotic subjects. In atherosclerosis, miR-21, 122, 130a, and 211 were significantly increased whereas miR-92a, 126, and 222 were markedly decreased. Serum levels of NT-pro-BNP and cTN-I correlated with each other and increased with the progression of atherosclerosis. Moreover, the levels of cTN-I and NT-pro-BNP were positively correlated with miR-21 and negatively correlated with miR-126. Integrating specific pattern of miRNA levels with NT-pro-BNP and/or cardiac troponin may improve the diagnosis of cardiovascular diseases.

Circulating miR-9* and miR-384-5p as potential indicators for trimethyltin-induced neurotoxicity

Circulating microRNAs (miRNAs) show promise as biomarkers due to their tissue-specific expression and high stability. This study was conducted to investigate whether nervous system-enriched miR-9* and hippocampus-enriched miR-384-5p could be indicators of neurotoxicity in serum. Rats were given a single administration of trimethyltin (TMT) chloride at 6, 9, or 12 mg/kg by gavage, and brain and serum were collected 1, 4, and 7 days after administration. MiR-9* and miR-384-5p levels in serum and hippocampus were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR), and their neurotoxicity detection sensitivities were compared with nervous symptoms, auditory response, and histopathology. TMT caused tremor, hypersensitivity, and decreased auditory response at 12 mg/kg on day 1 and at 9 mg/kg on day 4. Histopathologically, neural cell death and glial reaction were observed in brain (mainly hippocampus) at 12 mg/kg on day 1, 4, and 7 and at 6 and 9 mg/kg on day 4 and 7. MiR-9* and miR-384-5p levels were elevated in serum at 9 and 12 mg/kg on days 4 and 7 (at 9 mg/kg on day 7, miR-9* only) but were not changed in hippocampus. These miRNAs were considered to be elevated with the evolution of neural cell death and were thus considered possible novel indicators of neurotoxicity.

MicroRNAs as biomarkers of graft outcome

Dramatic improvements in short-term graft outcomes after solid organ transplantation over the past decade have not translated into major improvements in long-term allograft acceptance and patient survival. Innovative approaches to develop individualized therapy for the graft recipient are critically needed and have stimulated active research in the field of biomarker discovery. MicroRNAs (miRNAs) are small non-coding RNAs that function as important regulators of gene and protein expression by RNA interference. They are implicated in many biological processes and diseases. Their characteristics prompted their evaluation as candidate molecular markers to evaluate the transplant patient: their expression profile is specifically altered in pathological conditions, they can be easily detected and quantified in tissues, and they are highly stable in almost all body fluids, allowing the development of non-invasive approaches. We aimed to review the existing knowledge about miRNA biogenesis and function and summarize the recent findings demonstrating their potential use as biomarkers in solid organ transplantation. Although they still need to be validated in larger patient cohorts, miRNAs are not far from being used in transplant clinical practice as usefulness biomarkers. Ongoing multi-center trials should help to further define the clinical utility of miRNA profiles as biomarkers of allograft status and outcome.

Plasma microRNA-133a is a new marker for both acute myocardial infarction and underlying coronary artery stenosis

Background

Previous study demonstrated that miR-133a was released into blood from injured myocardium in cardiovascular diseases. However, the dynamic change of circulating miR-133a level in the early phase of acute myocardial infarction (AMI) and the correlation between miR-133a and severity of coronary stenosis in coronary heart disease (CHD) patients are not clear.

Methods and results

Three different cohorts (including 13 AMI patients, 176 angina pectoris patients and 127 control subjects) were enrolled to investigate the expression levels of circulating miR-133a in patients with myocardial ischemia and also the relationship between plasma miR-133a and severity of coronary stenosis. Plasma miR-133a levels of participants were examined by real-time quantitative PCR. Simultaneously, plasma cardiac troponin I (cTnI) concentrations were measured by ELISA assays. The results showed that circulating miR-133a level was significantly increased in AMI patients in time-dependent manner, and achieved a 72.1 fold peak at 21.6 ± 4.5 hours after the onset of AMI symptoms and exhibited a similar trend to plasma cTnI level. We also found that plasma miR-133a levels were higher in CHD patients than control group. Importantly, the levels of circulating miR-133a positively correlated with the severities of the coronary artery stenosis. Receiver operating characteristic (ROC) analysis revealed that circulating miR-133a had considerable diagnostic accuracy for CHD with an AUC of 0.918 (95% confidence interval 0.877-0.960).

Conclusions

Circulating miR-133a may be a new biomarker for AMI and as a potential diagnostic tool. And increased miR-133a level may be used to predict both the presence and severity of coronary lesions in CHD patients.