Efficacy and safety of CDR132L in patients with reduced left ventricular ejection fraction after myocardial infarction: Rationale and design of the HF-REVERT trial

AIM

Inhibition of microRNA (miR)-132 effectively prevents and reverses adverse cardiac remodelling, making it an attractive heart failure (HF) target. CDR132L, a synthetic antisense oligonucleotide selectively blocking pathologically elevated miR-132, demonstrated beneficial effects on left ventricular (LV) structure and function in relevant preclinical models, and was safe and well tolerated in a Phase 1b study in stable chronic HF patients. Patients with acute myocardial infarction (MI) and subsequent LV dysfunction and remodelling have limited therapeutic options, and may profit from early CDR132L treatment.

METHODS

The HF-REVERT (Phase 2, multicenter, randomized, parallel, 3-arm, placebo-controlled Study to Assess Efficacy and Safety of CDR132L in Patients with Reduced Left Ventricular Ejection Fraction after Myocardial Infarction) evaluates the efficacy and safety of CDR132L in HF patients post-acute MI (n = 280), comparing the effect of 5 and 10 mg/kg CDR132L, administered as three single intravenous doses 28 days apart, in addition to standard of care. Key inclusion criteria are the diagnosis of acute MI, the development of systolic dysfunction (LV ejection fraction ≤45%) and elevated N-terminal pro-B-type natriuretic peptide. The study consists of a 6-month double-blinded treatment period with the primary endpoint LV end-systolic volume index and relevant secondary endpoints, followed by a 6-month open-label observation period.

CONCLUSION

The HF-REVERT trial may underpin the concept of miR-132 inhibition to prevent or reverse cardiac remodelling in post-MI HF. The results will inform the design of subsequent outcome trials to test CDR132L in HF.

OSWG Recommended Approaches to the Nonclinical Pharmacokinetic (ADME) Characterization of Therapeutic Oligonucleotides

This white paper summarizes the recommendations of the absorption, distribution, metabolism, and excretion (ADME) Subcommittee of the Oligonucleotide Safety Working Group for the characterization of absorption, distribution, metabolism, and excretion of oligonucleotide (ON) therapeutics in nonclinical studies. In general, the recommended approach is similar to that for small molecule drugs. However, some differences in timing and/or scope may be warranted due to the greater consistency of results across ON classes as compared with the diversity among small molecule classes. For some types of studies, a platform-based approach may be appropriate; once sufficient data are available for the platform, presentation of these data should be sufficient to support development of additional ONs of the same platform. These recommendations can serve as a starting point for nonclinical study design and foundation for discussions with regulatory agencies.

Identification of Gene Expression Signatures for Phenotype-Specific Drug Targeting of Cardiac Fibrosis

We have designed translational animal models to investigate cardiac profibrotic gene signatures. Domestic pigs were treated with cardiotoxic drugs (doxorubicin, DOX, n = 5 or Myocet^®, MYO, n = 5) to induce replacement fibrosis via cardiotoxicity. Reactive interstitial fibrosis was triggered by LV pressure overload by artificial isthmus stenosis with stepwise developing myocardial hypertrophy and final fibrosis (Hyper, n = 3) or by LV volume overload in the adverse remodeled LV after myocardial infarction (RemoLV, n = 3). Sham interventions served as controls and healthy animals (Control, n = 3) served as a reference in sequencing study. Myocardial samples from the LV of each group were subjected to RNA sequencing. RNA-seq analysis revealed a clear distinction between the transcriptomes of myocardial fibrosis (MF) models. Cardiotoxic drugs activated the TNF-alpha and adrenergic signaling pathways. Pressure or volume overload led to the activation of FoxO pathway. Significant upregulation of pathway components enabled the identification of potential drug candidates used for the treatment of heart failure, such as ACE inhibitors, ARB, ß-blockers, statins and diuretics specific to the distinct MF models. We identified candidate drugs in the groups of channel blockers, thiostrepton that targets the FOXM1-regulated ACE conversion to ACE2, tyrosine kinases or peroxisome proliferator-activated receptor inhibitors. Our study identified different gene targets involved in the development of distinct preclinical MF protocols enabling tailoring expression signature-based approach for the treatment of MF.

Animal models and animal-free innovations for cardiovascular research: current status and routes to be explored. Consensus document of the ESC Working Group on Myocardial Function and the ESC Working Group on Cellular Biology of the Heart

Cardiovascular diseases represent a major cause of morbidity and mortality, necessitating research to improve diagnostics, and to discover and test novel preventive and curative therapies, all of which warrant experimental models that recapitulate human disease. The translation of basic science results to clinical practice is a challenging task, in particular for complex conditions such as cardiovascular diseases, which often result from multiple risk factors and comorbidities. This difficulty might lead some individuals to question the value of animal research, citing the translational 'valley of death', which largely reflects the fact that studies in rodents are difficult to translate to humans. This is also influenced by the fact that new, human-derived in vitro models can recapitulate aspects of disease processes. However, it would be a mistake to think that animal models do not represent a vital step in the translational pathway as they do provide important pathophysiological insights into disease mechanisms particularly on an organ and systemic level. While stem cell-derived human models have the potential to become key in testing toxicity and effectiveness of new drugs, we need to be realistic, and carefully validate all new human-like disease models. In this position paper, we highlight recent advances in trying to reduce the number of animals for cardiovascular research ranging from stem cell-derived models to in situ modelling of heart properties, bioinformatic models based on large datasets, and state-of-the-art animal models, which show clinically relevant characteristics observed in patients with a cardiovascular disease. We aim to provide a guide to help researchers in their experimental design to translate bench findings to clinical routine taking the replacement, reduction, and refinement (3R) as a guiding concept.

Novel antisense therapy targeting microRNA-132 in patients with heart failure

Background

Cardiac microRNA-132-3p (miR-132) levels are increased in patients with heart failure (HF) and mechanistically drive cardiac remodelling processes. CDR132L, a specific antisense oligonucleotide, is a first-in-class miR-132 inhibitor that attenuates and even reverses HF in preclinical models.

Purpose

The aim of the current clinical Phase 1b study was to assess safety, pharmacokinetics, target engagement, and exploratory pharmacodynamic effects of CDR132L in patients on standard-of-care therapy for chronic ischaemic HF in a randomized, placebo-controlled, double-blind, dose-escalation study.

Methods

Patients had left ventricular ejection fraction between ≥30% and <50% or amino terminal fragment of pro-brain natriuretic peptide (NT-proBNP) >125 ng/L at screening. Twenty-eight patients were randomized to receive CDR132L (0.32, 1, 3, and 10 mg/kg body weight) or placebo (0.9% saline) in two intravenous infusions, 4 weeks apart in four cohorts of seven (five verum and two placebo) patients each.

Results

CDR132L was safe and well tolerated, without apparent dose-limiting toxicity. A pharmacokinetic/pharmacodynamic dose modelling approach suggested an effective dose level at ≥1 mg/kg CDR132L. CDR132L treatment resulted in a dose-dependent, sustained miR-132 reduction in plasma. Patients given CDR132L ≥1 mg/kg displayed median 23.3% NT-proBNP reduction, vs. 0.9% median increase in the control group. CDR132L treatment induced significant QRS narrowing and positive trends for cardiac fibrosis biomarkers.

Conclusions

This study is the first clinical trial of an antisense drug in HF patients. CDR132L was safe and well tolerated, confirmed linear plasma pharmacokinetics with no signs of accumulation, and suggests cardiac functional improvements. The indicative efficacy of this drug is very encouraging justifying additional clinical studies to confirm the beneficial CDR132L pharmacodynamic effects for the treatment of HF.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Cardior Pharmaceuticals GmbH

Abstract 114: Safety And Efficacy Of CDR132L, A Novel Antisense Therapeutic Which Targets MicroRNA-132 In Heart Failure Patients

Cardiac microRNA-132-3p (miR-132) levels are elevated in people suffering with heart failure (HF) and mechanistically drive remodelling processes in the heart. Here we present CDR132L, a specific antisense oligonucleotide. It is a first-in-class miR-132 inhibitor that attenuates and even reverses HF in preclinical models. The aim of this clinical Phase 1b study was to assess safety, pharmacokinetics, target engagement, and pharmacodynamics of CDR132L in patients on therapy for chronic ischaemic HF in a randomized, placebo-controlled, double-blind, dose-escalation study. Inclusion criteria for participant patients was left ventricular ejection fraction between 30 and 50% or levels of amino terminal fragment of pro-brain natriuretic peptide (NT-proBNP) higher than 125 ng/L at screening. Twenty-eight patients were randomized to receive CDR132L (0.32, 1, 3, and 10 mg/kg body weight) or placebo (0.9% saline) in two intravenous infusions, 4 weeks apart. Randomization separated participants into four cohorts of seven (five verum and two placebo). Results revealed that CDR132L was safe and well tolerated, and there was no detectable dose-limiting toxicity. A pharmacokinetic/pharmacodynamic dose modelling approach suggested an effective dose level of ≥1 mg/kg CDR132L. CDR132L treatment resulted in a dose-dependent, sustained miR-132 reduction in plasma. Patients who were administered ≥1 mg/kg of CDR132L displayed 23.3% NT-proBNP reduction, whereas patients receiving placebo experienced a 0.9% increase. In addition, CDR132L treatment was observed to significantly reduce duration of the QRS interval. This is the first clinical trial in which an antisense oligonucleotide was administered as a therapeutic agent to HF patients. Linear plasma pharmacokinetics were confirmed, and there were no signs of accumulation. The application of this drug suggests cardiac functional improvements and cardiac remodelling. The efficacy of this drug is encouraging, and further clinical work with larger patient populations should follow. Although the study used small patient numbers, results suggest some clinical benefit in chronic HF patients on the top of standard of care. This included an improvement in HF severity and narrowing of the QRS complex. The pharmacodynamic findings presented here are encouraging as they confirm efficacy results seen in animal studies.

AntimiR-132 Attenuates Myocardial Hypertrophy in an Animal Model of Percutaneous Aortic Constriction

BACKGROUND

Pathological cardiac hypertrophy is a result of afterload-increasing pathologies including untreated hypertension and aortic stenosis. It features progressive adverse cardiac remodeling, myocardial dysfunction, capillary rarefaction, and interstitial fibrosis often leading to heart failure.

OBJECTIVES

This study aimed to establish a novel porcine model of pressure-overload-induced heart failure and to determine the effect of inhibition of microribonucleic acid 132 (miR-132) on heart failure development in this model.

METHODS

This study developed a novel porcine model of percutaneous aortic constriction by implantation of a percutaneous reduction stent in the thoracic aorta, inducing progressive remodeling at day 56 (d56) after pressure-overload induction. In this study, an antisense oligonucleotide specifically inhibiting miR-132 (antimiR-132), was regionally applied via intracoronary injection at d0 (percutaneous transverse aortic constriction induction) and d28.

RESULTS

At d56, antimiR-132 treatment diminished cardiomyocyte cross-sectional area (188.9 ± 2.8 vs. 258.4 ± 9.0 μm² in untreated hypertrophic hearts) and improved global cardiac function (ejection fraction 48.9 ± 1.0% vs. 36.1 ± 1.7% in control hearts). Moreover, at d56 antimiR-132-treated hearts displayed less increase of interstitial fibrosis compared with sham-operated hearts (Δsham 1.8 ± 0.5%) than control hearts (Δsham 10.8 ± 0.6%). Of note, cardiac platelet and endothelial cell adhesion molecule 1⁺ capillary density was higher in the antimiR-132-treated hearts (647 ± 20 cells/mm²) compared with in the control group (485 ± 23 cells/mm²).

CONCLUSIONS

The inhibition of miR-132 is a valid strategy in prevention of heart failure progression in hypertrophic heart disease and may be developed as a treatment for heart failure of nonischemic origin.

Targeting muscle-enriched long non-coding RNA H19 reverses pathological cardiac hypertrophy

AIMS

Pathological cardiac remodelling and subsequent heart failure represents an unmet clinical need. Long non-coding RNAs (lncRNAs) are emerging as crucial molecular orchestrators of disease processes, including that of heart diseases. Here, we report on the powerful therapeutic potential of the conserved lncRNA H19 in the treatment of pathological cardiac hypertrophy.

METHOD AND RESULTS

Pressure overload-induced left ventricular cardiac remodelling revealed an up-regulation of H19 in the early phase but strong sustained repression upon reaching the decompensated phase of heart failure. The translational potential of H19 is highlighted by its repression in a large animal (pig) model of left ventricular hypertrophy, in diseased human heart samples, in human stem cell-derived cardiomyocytes and in human engineered heart tissue in response to afterload enhancement. Pressure overload-induced cardiac hypertrophy in H19 knock-out mice was aggravated compared to wild-type mice. In contrast, vector-based, cardiomyocyte-directed gene therapy using murine and human H19 strongly attenuated heart failure even when cardiac hypertrophy was already established. Mechanistically, using microarray, gene set enrichment analyses and Chromatin ImmunoPrecipitation DNA-Sequencing, we identified a link between H19 and pro-hypertrophic nuclear factor of activated T cells (NFAT) signalling. H19 physically interacts with the polycomb repressive complex 2 to suppress H3K27 tri-methylation of the anti-hypertrophic Tescalcin locus which in turn leads to reduced NFAT expression and activity.

CONCLUSION

H19 is highly conserved and down-regulated in failing hearts from mice, pigs and humans. H19 gene therapy prevents and reverses experimental pressure-overload-induced heart failure. H19 acts as an anti-hypertrophic lncRNA and represents a promising therapeutic target to combat pathological cardiac remodelling.

Novel antisense therapy targeting microRNA-132 in patients with heart failure: results of a first-in-human Phase 1b randomized, double-blind, placebo-controlled study

AIMS

Cardiac microRNA-132-3p (miR-132) levels are increased in patients with heart failure (HF) and mechanistically drive cardiac remodelling processes. CDR132L, a specific antisense oligonucleotide, is a first-in-class miR-132 inhibitor that attenuates and even reverses HF in preclinical models. The aim of the current clinical Phase 1b study was to assess safety, pharmacokinetics, target engagement, and exploratory pharmacodynamic effects of CDR132L in patients on standard-of-care therapy for chronic ischaemic HF in a randomized, placebo-controlled, double-blind, dose-escalation study (NCT04045405).

METHODS AND RESULTS

Patients had left ventricular ejection fraction between ≥30% and <50% or amino terminal fragment of pro-brain natriuretic peptide (NT-proBNP) >125 ng/L at screening. Twenty-eight patients were randomized to receive CDR132L (0.32, 1, 3, and 10 mg/kg body weight) or placebo (0.9% saline) in two intravenous infusions, 4 weeks apart in four cohorts of seven (five verum and two placebo) patients each. CDR132L was safe and well tolerated, without apparent dose-limiting toxicity. A pharmacokinetic/pharmacodynamic dose modelling approach suggested an effective dose level at ≥1 mg/kg CDR132L. CDR132L treatment resulted in a dose-dependent, sustained miR-132 reduction in plasma. Patients given CDR132L ≥1 mg/kg displayed a median 23.3% NT-proBNP reduction, vs. a 0.9% median increase in the control group. CDR132L treatment induced significant QRS narrowing and encouraging positive trends for relevant cardiac fibrosis biomarkers.

CONCLUSION

This study is the first clinical trial of an antisense drug in HF patients. CDR132L was safe and well tolerated, confirmed linear plasma pharmacokinetics with no signs of accumulation, and suggests cardiac functional improvements. Although this study is limited by the small patient numbers, the indicative efficacy of this drug is very encouraging justifying additional clinical studies to confirm the beneficial CDR132L pharmacodynamic effects for the treatment of HF.

CDR132L improves systolic and diastolic function in a large animal model of chronic heart failure

Aims

Cardiac miR-132 activation leads to adverse remodelling and pathological hypertrophy. CDR132L is a synthetic lead-optimized oligonucleotide inhibitor with proven preclinical efficacy and safety in heart failure (HF) early after myocardial infarction (MI), and recently completed clinical evaluation in a Phase 1b study (NCT04045405). The aim of the current study was to assess safety and efficacy of CDR132L in a clinically relevant large animal (pig) model of chronic heart failure following MI.

Methods and results

In a chronic model of post-MI HF, slow-growing pigs underwent 90 min left anterior descending artery occlusion followed by reperfusion. Animals were randomized and treatment started 1-month post-MI. Monthly intravenous (IV) treatments of CDR132L over 3 or 5 months (3× or 5×) were applied in a blinded randomized placebo-controlled fashion. Efficacy was evaluated based on serial magnetic resonance imaging, haemodynamic, and biomarker analyses. The treatment regime provided sufficient tissue exposure and CDR132L was well tolerated. Overall, CDR132L treatment significantly improved cardiac function and reversed cardiac remodelling. In addition to the systolic recovery, diastolic function was also ameliorated in this chronic model of HF.

Conclusion

Monthly repeated dosing of CDR132L is safe and adequate to provide clinically relevant exposure and therapeutic efficacy in a model of chronic post-MI HF. CDR132L thus should be explored as treatment for the broad area of chronic heart failure.

Association between Circular RNA CDR1as and Post-Infarction Cardiac Function in Pig Ischemic Heart Failure: Influence of the Anti-Fibrotic Natural Compounds Bufalin and Lycorine

Anti-fibrotic therapies are of increasing interest to combat cardiac remodeling and heart failure progression. Recently, anti-fibrotic circular RNAs (circRNAs) have been identified in human and rodent cardiac tissue. In vivo (rodent) experiments proved cardiac anti-fibrotic effects of the natural compounds bufalin and lycorine by downregulating miRNA-671-5p, associated with a theoretic increase in the tissue level of circRNA CDR1as. Accordingly, we hypothesized that both anti-fibrotic drugs may inhibit focal myocardial fibrosis of the remodeled left ventricle (LV) also in a translational large animal model of heart failure (HF). Domestic pigs were repeatedly treated with subcutaneous injections of either bufalin, lycorine, or saline, (n = 5/group) between days 7-21 post acute myocardial infarction (AMI). At the 2-month follow-up, both bufalin and lycorine led to significantly reduced cardiac fibrosis. Bufalin treatment additionally led to smaller end-diastolic volumes, higher LV ejection fraction (EF), and increased expression of CDR1as of the AMI region. Elevated tissue levels of the circRNA CDR1as in the AMI region of the pig heart correlated significantly with LV and right ventricular EF, LV stroke volume, and negatively with infarct size. In conclusion, we successfully identified the circRNA CDR1as in pig hearts and show a significant association with improved LV and RV function by anti-fibrotic therapies in a translational animal model of HF.

Pharmacokinetic Studies of Antisense Oligonucleotides Using MALDI-TOF Mass Spectrometry

Cardiac diseases are the most frequent causes of death in industrialized countries. Pathological remodeling of the heart muscle is caused by several etiologies such as prolonged hypertension or injuries that can lead to myocardial infarction and in serious cases also the death of the patient. The micro-RNA miR-132 has been identified as a master-switch in the development of cardiac hypertrophy and adverse remodeling. In this study, MALDI-TOF mass spectrometry (MS) was utilized to establish a robust and fast method to sensitively detect and accurately quantify anti-microRNA (antimiR) oligonucleotides in blood plasma. An antimiR oligonucleotide isolation protocol containing an ethanol precipitation step with glycogen as oligonucleotide carrier as well as a robust and reproducible MS-analysis procedure has been established. Proteinase K treatment was crucial for releasing antimiR oligonucleotides from plasma- as well as cellular proteins and reducing background derived from biological matrices. AntimiR oligonucleotide detection was achieved from samples of studies in different animal models such as mouse and pig where locked nucleic acids-(LNA)-modified antimiR oligonucleotides have been used to generate pharmacokinetic data.

Preclinical development of a miR-132 inhibitor for heart failure treatment

Despite proven efficacy of pharmacotherapies targeting primarily global neurohormonal dysregulation, heart failure (HF) is a growing pandemic with increasing burden. Treatments mechanistically focusing at the cardiomyocyte level are lacking. MicroRNAs (miRNA) are transcriptional regulators and essential drivers of disease progression. We previously demonstrated that miR-132 is both necessary and sufficient to drive the pathological cardiomyocytes growth, a hallmark of adverse cardiac remodelling. Therefore, miR-132 may serve as a target for HF therapy. Here we report further mechanistic insight of the mode of action and translational evidence for an optimized, synthetic locked nucleic acid antisense oligonucleotide inhibitor (antimiR-132). We reveal the compound’s therapeutic efficacy in various models, including a clinically highly relevant pig model of HF. We demonstrate favourable pharmacokinetics, safety, tolerability, dose-dependent PK/PD relationships and high clinical potential for the antimiR-132 treatment scheme.

miR-132 was shown to drive pathological cardiac remodeling, a hallmark of heart failure. Here, the authors show that an antisense inhibitor of miR-132 has favourable pharmacokinetics, safety-tolerability and preclinical efficacy in mouse and porcine models of heart failure.

Natural Compound Library Screening Identifies New Molecules for the Treatment of Cardiac Fibrosis and Diastolic Dysfunction

BACKGROUND

Myocardial fibrosis is a hallmark of cardiac remodeling and functionally involved in heart failure development, a leading cause of deaths worldwide. Clinically, no therapeutic strategy is available that specifically attenuates maladaptive responses of cardiac fibroblasts, the effector cells of fibrosis in the heart. Therefore, our aim was to develop novel antifibrotic therapeutics based on naturally derived substance library screens for the treatment of cardiac fibrosis.

METHODS

Antifibrotic drug candidates were identified by functional screening of 480 chemically diverse natural compounds in primary human cardiac fibroblasts, subsequent validation, and mechanistic in vitro and in vivo studies. Hits were analyzed for dose-dependent inhibition of proliferation of human cardiac fibroblasts, modulation of apoptosis, and extracellular matrix expression. In vitro findings were confirmed in vivo with an angiotensin II-mediated murine model of cardiac fibrosis in both preventive and therapeutic settings, as well as in the Dahl salt-sensitive rat model. To investigate the mechanism underlying the antifibrotic potential of the lead compounds, treatment-dependent changes in the noncoding RNAome in primary human cardiac fibroblasts were analyzed by RNA deep sequencing.

RESULTS

High-throughput natural compound library screening identified 15 substances with antiproliferative effects in human cardiac fibroblasts. Using multiple in vitro fibrosis assays and stringent selection algorithms, we identified the steroid bufalin (from Chinese toad venom) and the alkaloid lycorine (from Amaryllidaceae species) to be effective antifibrotic molecules both in vitro and in vivo, leading to improvement in diastolic function in 2 hypertension-dependent rodent models of cardiac fibrosis. Administration at effective doses did not change plasma damage markers or the morphology of kidney and liver, providing the first toxicological safety data. Using next-generation sequencing, we identified the conserved microRNA 671-5p and downstream the antifibrotic selenoprotein P1 as common effectors of the antifibrotic compounds.

CONCLUSIONS

We identified the molecules bufalin and lycorine as drug candidates for therapeutic applications in cardiac fibrosis and diastolic dysfunction.

Studying Interactions between 2'-O-Me-Modified Inhibitors and MicroRNAs Utilizing Microscale Thermophoresis

Besides the acquisition of pharmacokinetic parameters of antisense oligonucleotide microRNA (miRNA) inhibitors, such as measuring in vivo concentration, their pharmacodynamic characteristics are also of interest. An emerging and straightforward method for studying molecular interactions is microscale thermophoresis (MST). This technique makes it possible to study interactions between miRNAs and various oligonucleotide inhibitors, independent of the chemical modifications of the inhibitors or their respective target structure, with very little sample volume required compared to competitive techniques, such as surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). Interaction studies between these inhibitors and their respective target structures were performed, and they allowed the assessment of binding characteristics and parameters, such as EC₅₀ for a number of these inhibitors, with little effort. Furthermore, MST could be utilized for obtaining kinetic binding data of the Argonaute-2 protein with a miRNA, which showed a possible RNA-induced silencing complex (RISC)-mediated turnover of inhibited miRNAs.

TIP30 counteracts cardiac hypertrophy and failure by inhibiting translational elongation

Pathological cardiac overload induces myocardial protein synthesis and hypertrophy, which predisposes to heart failure. To inhibit hypertrophy therapeutically, the identification of negative regulators of cardiomyocyte protein synthesis is needed. Here, we identified the tumor suppressor protein TIP30 as novel inhibitor of cardiac hypertrophy and dysfunction. Reduced TIP30 levels in mice entailed exaggerated cardiac growth during experimental pressure overload, which was associated with cardiomyocyte cellular hypertrophy, increased myocardial protein synthesis, reduced capillary density, and left ventricular dysfunction. Pharmacological inhibition of protein synthesis improved these defects. Our results are relevant for human disease, since we found diminished cardiac TIP30 levels in samples from patients suffering from end‐stage heart failure or hypertrophic cardiomyopathy. Importantly, therapeutic overexpression of TIP30 in mouse hearts inhibited cardiac hypertrophy and improved left ventricular function during pressure overload and in cardiomyopathic mdx mice. Mechanistically, we identified a previously unknown anti‐hypertrophic mechanism, whereby TIP30 binds the eukaryotic elongation factor 1A (eEF1A) to prevent the interaction with its essential co‐factor eEF1B2 and translational elongation. Therefore, TIP30 could be a therapeutic target to counteract cardiac hypertrophy.

miR-212/132 Cluster Modulation Prevents Doxorubicin-Mediated Atrophy and Cardiotoxicity

Improved therapy of cancer has significantly increased the lifespan of patients. However, cancer survivors face an increased risk of cardiovascular complications due to adverse effects of cancer therapies. The chemotherapy drug doxorubicin is well known to induce myofibril damage and cardiac atrophy. Our aim was to test potential counteracting effects of the pro-hypertrophic miR-212/132 family in doxorubicin-induced cardiotoxicity. In vitro, overexpression of the pro-hypertrophic miR-212/132 cluster in primary rodent and human iPSC-derived cardiomyocytes inhibited doxorubicin-induced toxicity. Next, a disease model of doxorubicin-induced cardiotoxicity was established in male C57BL/6N mice. Mice were administered either adeno-associated virus (AAV)9-control or AAV9-miR-212/132 to achieve myocardial overexpression of the miR-212/132 cluster. AAV9-mediated overexpression limited cardiac atrophy by increasing left ventricular mass and wall thickness, decreased doxorubicin-mediated apoptosis, and prevented myofibril damage. Based on a transcriptomic profiling we identified fat storage-inducing transmembrane protein 2 (Fitm2) as a novel target and downstream effector molecule responsible, at least in part, for the observed miR-212/132 anti-cardiotoxic effects. Overexpression of Fitm2 partially reversed the effects of miR-212/132. Overexpression of the miR-212/132 family reduces development of doxorubicin-induced cardiotoxicity and thus could be a therapeutic entry point to limit doxorubicin-mediated adverse cardiac effects.

Abstract 251: miRNA Mapping of Cardiac Endothelial and Fibroblast Cells during Hypertrophy Progression

MicroRNAs (MiRNA/miRs) are known key players in cardiovascular disorders. Here we created and analyzed a global miRNA map in isolated cardiac endothelial and fibroblast cells during hypertrophy progression.

Hypertrophy was induced in male C57BL/6 mice by trans-aortic constriction (TAC). Hypertrophic phenotyping was performed at 3 days (3d), 2 weeks (2w) or 4 weeks (4w) post- SHAM/TAC operation, using Millar system and echocardiography. Thereafter, pure single cell fractions from hearts were recovered by retrograde collagenase-II perfusion, followed by pre-plating of fibroblasts and magnetic sorting of endothelial cells. Transcriptomic analysis was performed on RNA isolated from different heart cell fractions at 3d, 2w or 4w post-SHAM/TAC. Additional 6w and 13w SHAM/TAC groups were included for validation of selected miRNAs. Cytokine secretome was performed using multiplex assay after transfection of a miR library to primary cardiac fibroblasts. Unsupervised hierarchical clustering revealed specific miRNA profile of each cardiac cell fraction. Principle component analysis projected strong effect of individual cellular compartments. Based on miRnome screening, miR-709, miR-30e-5p, miR-146a, miR-34a and miR-204, miR-1187 were validated by RTPCR to confirm spatial and temporal regulation (n=3-5, p<0.05) of these miRNAs in non-cardiomyocyte fractions. Corresponding time-dependent downregulation of miR-146a targets, Pten and Timp-2, was also observed. Cytokine secretome analysis upon miR-precursor library transfection in cardiac fibroblasts confirmed an increase in FGF, LIF-1, MCP-1, MIP-1 secretion (1.5-5 folds) by miR-146a and miR-34a. Gradual activation of the TGF beta pathway in endothelial cells may initiate endothelial to mesenchymal transition, whereas cytokine secretion from fibroblasts may affect the cellular hemostasis.

Our study represents a global miRNome of cardiac endothelial and fibroblast compartments during progressive hypertrophy to better understand the time dependent molecular changes in non-cardiomyocyte compartment during pressure-overload induced cardiac remodeling. The collective influence of miRNA deregulation may be linked to different pathways responsible for cell-proliferation, inflammation and fibrosis with the progression of hypertrophy.

Circulating microRNA-132 levels improve risk prediction for heart failure hospitalization in patients with chronic heart failure

AIMS

Non-coding microRNAs (miRNAs) are critically involved in cardiovascular pathophysiology. Since they are measurable in most body fluids, they have been proposed as circulating biomarkers. We examined the prognostic value of a specific candidate miRNA in a large cohort of patients with chronic heart failure (HF) enrolled in a multicentre clinical trial.

METHODS AND RESULTS

Plasma levels of miR-132 were measured using miRNA-specific PCR-based technologies at randomization in 953 patients with chronic, symptomatic HF from the GISSI-Heart Failure trial. The association with fatal (all-cause and cardiovascular death) and non-fatal events (time to first admission to hospital for cardiovascular reasons or worsening of HF) and the incremental risk prediction were estimated in adjusted models. Higher circulating miR-132 levels were independently associated with younger age, better renal filtration, ischaemic aetiology of HF, more severe HF symptoms, higher diastolic blood pressure, higher cholesterol, and male sex. After extensive adjustment for demographic, clinical, and echocardiographic risk factors and baseline NT-proBNP concentrations, miR-132 remained associated only with HF hospitalizations (hazard ratio 0.79, 95% confidence interval 0.66-0.95, P = 0.01) and improved its risk prediction with the continuous net reclassification index (cNRI 0.205, P = 0.001).

CONCLUSION

In well characterized patients with chronic HF, circulating miR-132 levels rise with the severity of HF. Lower circulating miR-132 levels improved risk prediction for HF readmission beyond traditional risk factors, but not for mortality. MiR-132 may be helpful to intensify strategies aimed at reducing re-hospitalization, which has a substantial health and economic burden in HF.

Inhibition of the Cardiac Fibroblast–Enriched lncRNA Meg3 Prevents Cardiac Fibrosis and Diastolic Dysfunction

Rationale:

Cardiac fibroblasts (CFs) drive extracellular matrix remodeling after pressure overload, leading to fibrosis and diastolic dysfunction. Recent studies described the role of long noncoding RNAs (lncRNAs) in cardiac pathologies. Nevertheless, detailed reports on lncRNAs regulating CF biology and describing their implication in cardiac remodeling are still missing.

Objective:

Here, we aimed at characterizing lncRNA expression in murine CFs after chronic pressure overload to identify CF-enriched lncRNAs and investigate their function and contribution to cardiac fibrosis and diastolic dysfunction.

Methods and Results:

Global lncRNA profiling identified several dysregulated transcripts. Among them, the lncRNA maternally expressed gene 3 ( Meg3 ) was found to be mostly expressed by CFs and to undergo transcriptional downregulation during late cardiac remodeling. In vitro, Meg3 regulated the production of matrix metalloproteinase-2 (MMP-2). GapmeR-mediated silencing of Meg3 in CFs resulted in the downregulation of Mmp -2 transcription, which, in turn, was dependent on P53 activity both in the absence and in the presence of transforming growth factor-β I. Chromatin immunoprecipitation showed that further induction of Mmp -2 expression by transforming growth factor-β I was blocked by Meg3 silencing through the inhibition of P53 binding on the Mmp-2 promoter. Consistently, inhibition of Meg3 in vivo after transverse aortic constriction prevented cardiac MMP-2 induction, leading to decreased cardiac fibrosis and improved diastolic performance.

Conclusions:

Collectively, our findings uncover a critical role for Meg3 in the regulation of MMP-2 production by CFs in vitro and in vivo, identifying a new player in the development of cardiac fibrosis and potential new target for the prevention of cardiac remodeling.

MicroRNA-Based Therapy of GATA2-Deficient Vascular Disease

BACKGROUND

The transcription factor GATA2 orchestrates the expression of many endothelial-specific genes, illustrating its crucial importance for endothelial cell function. The capacity of this transcription factor in orchestrating endothelial-important microRNAs (miRNAs/miR) is unknown.

METHODS

Endothelial GATA2 was functionally analyzed in human endothelial cells in vitro. Endogenous short interfering RNA-mediated knockdown and lentiviral-based overexpression were applied to decipher the capacity of GATA2 in regulating cell viability and capillary formation. Next, the GATA2-dependent miR transcriptome was identified by using a profiling approach on the basis of quantitative real-time polymerase chain reaction. Transcriptional control of miR promoters was assessed via chromatin immunoprecipitation, luciferase promoter assays, and bisulfite sequencing analysis of sites in proximity. Selected miRs were modulated in combination with GATA2 to identify signaling pathways at the angiogenic cytokine level via proteome profiler and enzyme-linked immunosorbent assays. Downstream miR targets were identified via bioinformatic target prediction and luciferase reporter gene assays. In vitro findings were translated to a mouse model of carotid injury in an endothelial GATA2 knockout background. Nanoparticle-mediated delivery of proangiogenic miR-126 was tested in the reendothelialization model.

RESULTS

GATA2 gain- and loss-of-function experiments in human umbilical vein endothelial cells identified a key role of GATA2 as master regulator of multiple endothelial functions via miRNA-dependent mechanisms. Global miRNAnome-screening identified several GATA2-regulated miRNAs including miR-126 and miR-221. Specifically, proangiogenic miR-126 was regulated by GATA2 transcriptionally and targeted antiangiogenic SPRED1 and FOXO3a contributing to GATA2-mediated formation of normal vascular structures, whereas GATA2 deficiency led to vascular abnormalities. In contrast to GATA2 deficiency, supplementation with miR-126 normalized vascular function and expression profiles of cytokines contributing to proangiogenic paracrine effects. GATA2 silencing resulted in endothelial DNA hypomethylation leading to induced expression of antiangiogenic miR-221 by GATA2-dependent demethylation of a putative CpG island in the miR-221 promoter. Mechanistically, a reverted GATA2 phenotype by endogenous suppression of miR-221 was mediated through direct proangiogenic miR-221 target genes ICAM1 and ETS1. In a mouse model of carotid injury, GATA2 was reduced, and systemic supplementation of miR-126-coupled nanoparticles enhanced miR-126 availability in the carotid artery and improved reendothelialization of injured carotid arteries in vivo.

CONCLUSIONS

GATA2-mediated regulation of miR-126 and miR-221 has an important impact on endothelial biology. Hence, modulation of GATA2 and its targets miR-126 and miR-221 is a promising therapeutic strategy for treatment of many vascular diseases.

Abstract 72: The Tumor Suppressor Gene Tip30 Supports Cardiac Compensation During Overload and Inhibits Myocardial Protein Synthesis

Background: Here, we examined the currently unknown cardiac expression and function of Tip30, which has previously emerged as a tumor suppressor gene.

Results: Myocardial TIP30 mRNA and protein were significantly upregulated in response to experimental transverse aortic constriction (TAC). TIP30 contributed to cardiac compensation, since a reduction of cardiac TIP30 in heterozygous Tip30 knock-out mice (HET) led to exaggerated hypertrophy and cardiac dysfunction compared to wild-type mice (WT) after TAC. In turn, TIP30 overexpression by an adenovirus in isolated neonatal cardiomyocytes or by an adeno-associated-virus (AAV9) in mouse hearts led to reduced hypertrophy after pro-hypertrophic stimulation in cells and reduced hypertrophy and improved cardiac function after TAC in mice. Interestingly, cardiac TIP30 levels were strongly diminished in mouse models of genetic cardiomyopathy (mdx mice) and in endstage human cardiomyopathy. Reduced cardiac TIP30 contributed to disease progression, since reconstitution of myocardial TIP30 via AAV9 in mdx mice prevented hypertrophy and improved cardiac function. A protein interaction screen and subsequent characterization showed that TIP30 interacts with the middle domain of the eukaryotic translation factor 1A1 (eEF1A1). As revealed by immunoprecipitation and in situ proximity ligation assay, the cellular interaction of eEF1A1 and its essential cofactor eEF1B was diminished by TIP30 overexpression, but enhanced in cardiomyocytes isolated from HET mice after pro-hypertrophic stimulation. Because eEF1A1 is a crucial mediator of translational elongation, we hypothesized that TIP30 regulates cardiac hypertrophy by interfering with protein synthesis. Indeed, overexpression of TIP30 inhibited cardiac protein synthesis during pro-hypertrophic stimulation, while reduced TIP30 levels in HET (vs. WT) mice triggered enhanced protein synthesis after TAC. Interestingly, administration of the eEF1A1 inhibitor narciclasine ablated the increased hypertrophy in HET mice after TAC.

Conclusion: TIP30 inhibits protein synthesis by binding to eEF1A1 and inhibiting its interaction with eEF1B. It thereby reduces pathological hypertrophy and supports cardiac compensation during overload.

miR-21 promotes fibrosis in an acute cardiac allograft transplantation model

AIMS

Cardiac transplantation is the only curative therapy for end-stage heart failure. Fibrosis is one of the major causes for impaired function of cardiac allografts. MicroRNAs, a class of small non-coding RNAs, play a critical role in the development of cardiovascular disease, but the role of microRNAs in cardiac allograft failure is not well understood.

METHODS AND RESULTS

To uncover a role of microRNAs during cardiac graft fibrosis, we generated global microRNA profiles in allogeneic (BALB/c in C57BL/6N) and isogeneic (C57BL/6N in C57BL/6N) murine hearts after transplantation. miR-21 together with cardiac fibrosis was increased in cardiac allografts compared with isografts. Likewise, patients with cardiac rejection after heart transplantation showed increased cardiac miR-21 levels. miR-21 was induced upon treatment with IL-6 in a monocyte cell line. Overexpression of miR-21 in this monocyte cell line activated a fibrotic gene programme and promoted monocyte-to-fibrocyte transition together with activation of chemokine (C-C) motif ligand 2 (monocyte chemoattractant protein 1) via the phosphatase and tensin homologue/activator protein 1 regulatory axis. In vivo, both genetic and pharmacological inhibition of miR-21 successfully reduced fibrosis and fibrocyte accumulation in cardiac allografts.

CONCLUSION

Thus, inhibition of miR-21 is a novel strategy to target fibrosis development in cardiac allografts.

Osteopontin is indispensible for AP1-mediated angiotensin II-related miR-21 transcription during cardiac fibrosis

Aims

Osteopontin (OPN) is a multifunctional cytokine critically involved in cardiac fibrosis. However, the underlying mechanisms are unresolved. Non-coding RNAs are powerful regulators of gene expression and thus might mediate this process.

Methods and results

OPN and miR-21 were significantly increased in cardiac biopsies of patients with myocardial fibrosis. Ang II infusion via osmotic minipumps led to specific miRNA regulations with miR-21 being strongly induced in wild-type (WT) but not OPN knockout (KO) mice. This was associated with enhanced cardiac collagen content, myofibroblast activation, ERK-MAP kinase as well as AKT signalling pathway activation and a reduced expression of Phosphatase and Tensin Homologue (PTEN) as well as SMAD7 in WT but not OPN KO mice. In contrast, cardiotropic AAV9-mediated overexpression of OPN in vivo further enhanced cardiac fibrosis. In vitro, Ang II induced expression of miR-21 in WT cardiac fibroblasts, while miR-21 levels were unchanged in OPN KO fibroblasts. As pri-miR-21 was also increased by Ang II, we studied potential involved upstream regulators; Electrophoretic Mobility Shift and Chromatin Immunoprecipitation analyses confirmed activation of the miR-21 upstream-transcription factor AP-1 by Ang II. Recombinant OPN directly activated miR-21, enhanced fibrosis, and activated the phosphoinositide 3-kinase pathway. Locked nucleic acid-mediated miR-21 silencing ameliorated cardiac fibrosis development in vivo.

Conclusion

In cardiac fibrosis related to Ang II, miR-21 is transcriptionally activated and targets PTEN/SMAD7 resulting in increased fibroblast survival. OPN KO animals are protected from miR-21 increase and fibrosis development due to impaired AP-1 activation and fibroblast activation.

Osteopontin (OPN) is a pleiotropic cytokine, which has been shown to be a pivotal factor in myofibroblast activation in cardiac fibrosis, thereby acting as a strong driver of heart failure development in humans. MicroRNAs (miRNAs) are under intense investigation as powerful regulators of various diseases. First phase I and II clinical trials using miRNA inhibitors have been initiated. We here show, that OPN is essential in the activation of AP-1 and subsequent transcription of miR-21 in cardiac fibrosis related to Ang II. OPN null mice are protected from miR-21 increase and fibrosis development due to impaired AP-1 activation and fibroblast activation. In the future, these findings may result in miRNA therapeutic approaches to treat patients with cardiac remodelling, in which levels of OPN and miR-21 are increased.

Zinc-α2-Glycoprotein Exerts Antifibrotic Effects in Kidney and Heart

Zinc-α2-glycoprotein (AZGP1) is a secreted protein synthesized by epithelial cells and adipocytes that has roles in lipid metabolism, cell cycling, and cancer progression. Our previous findings in AKI indicated a new role for AZGP1 in the regulation of fibrosis, which is a unifying feature of CKD. Using two models of chronic kidney injury, we now show that mice with genetic AZGP1 deletion develop significantly more kidney fibrosis. This destructive phenotype was rescued by injection of recombinant AZGP1. Exposure of AZGP1-deficient mice to cardiac stress by thoracic aortic constriction revealed that antifibrotic effects were not restricted to the kidney but were cardioprotective. In vitro, recombinant AZGP1 inhibited kidney epithelial dedifferentiation and antagonized fibroblast activation by negatively regulating TGF-β signaling. Patient sera with high levels of AZGP1 similarly attenuated TGF-β signaling in fibroblasts. Taken together, these findings indicate a novel role for AZGP1 as a negative regulator of fibrosis progression, suggesting that recombinant AZGP1 may have translational effect for treating fibrotic disease.

Plasma and tissue homoarginine concentrations in healthy and obese humans

Increased cardiovascular risk associated with obesity cannot be fully explained by traditional risk markers. We therefore assessed plasma and interstitial concentrations of the novel cardiovascular risk biomarker homoarginine (hArg) in 18 individuals without signs of cardiovascular disease, including 4 morbidly obese subjects before and after bariatric surgery and subsequent weight reduction of 36 ± 7 kg. hArg concentrations were greater in skeletal muscle compared with adipose tissue. Plasma and tissue hArg concentrations did not correlate with BMI. Adipose tissue interstitial hArg concentrations were not affected by obesity, an oral glucose load, or dramatic weight loss. In conclusion, obesity seems not to have a major effect on hArg homeostasis, and hArg may not explain the added cardiovascular risk associated with obesity. Yet, given the small sample size of the study, the significance of hArg in obesity should be investigated in a larger population.

Antiandrogenic therapy with finasteride attenuates cardiac hypertrophy and left ventricular dysfunction

BACKGROUND

In comparison with men, women have a better prognosis when experiencing aortic valve stenosis, hypertrophic cardiomyopathy, or heart failure. Recent data suggest that androgens like testosterone or the more potent dihydrotestosterone contribute to the development of cardiac hypertrophy and failure. Therefore, we analyzed whether antiandrogenic therapy with finasteride, which inhibits the generation of dihydrotestosterone by the enzyme 5-α-reductase, improves pathological ventricular remodeling and heart failure.

METHODS AND RESULTS

We found a strongly induced expression of all 3 isoforms of the 5-α-reductase (Srd5a1 to Srd5a3) in human and mouse hearts with pathological hypertrophy, which was associated with increased myocardial accumulation of dihydrotestosterone. Starting 1 week after the induction of pressure overload by transaortic constriction, mice were treated with finasteride for 2 weeks. Cardiac function, hypertrophy, dilation, and fibrosis were markedly improved in response to finasteride treatment in not only male, but also in female mice. In addition, finasteride also very effectively improved cardiac function and mortality after long-term pressure overload and prevented disease progression in cardiomyopathic mice with myocardial Gαq overexpression. Mechanistically, finasteride, by decreasing dihydrotestosterone, potently inhibited hypertrophy and Akt-dependent prohypertrophic signaling in isolated cardiac myocytes, whereas the introduction of constitutively active Akt blunted these effects of finasteride.

CONCLUSIONS

Finasteride, which is currently used in patients to treat prostate disease, potently reverses pathological cardiac hypertrophy and dysfunction in mice and might be a therapeutic option for heart failure.

MicroRNAs play a role in spontaneous recovery from acute liver failure

Acute liver failure (ALF) represents a life-threatening situation characterized by sudden and massive liver cell death in the absence of preexisting liver disease. Although most patients require liver transplantation to prevent mortality, some recover spontaneously and show complete liver regeneration. Because of the rarity of this disease, the molecular mechanisms regulating liver regeneration in ALF patients remain largely unknown. In this study, we investigated the role of microRNAs (miRs) that have been implicated in liver injury and regeneration in sera from ALF patients (n = 63). Patients with spontaneous recovery from ALF showed significantly higher serum levels of miR-122, miR-21, and miR-221, compared to nonrecovered patients. In liver biopsies, miR-21 and miR-221 displayed a reciprocal expression pattern and were found at lower levels in the spontaneous survivors, whereas miR-122 was elevated in both serum and liver tissue of those patients. As compared to nonrecovered patients, liver tissue of spontaneous survivors revealed not only increased hepatocyte proliferation, but also a strong down-regulation of miRNA target genes that impair liver regeneration, including heme oxygenase-1, programmed cell death 4, and the cyclin-dependent kinase inhibitors p21, p27, and p57.

CONCLUSION

Our data suggest that miR-122, miR-21, and miR-221 are involved in liver regeneration and might contribute to spontaneous recovery from ALF. Prospective studies will show whether serological detection of those miRNAs might be of prognostic value to predict ALF outcome.

Vascular importance of the miR-212/132 cluster

RATIONALE

Many processes in endothelial cells including angiogenic responses are regulated by microRNAs. However, there is limited information available about their complex cross-talk in regulating certain endothelial functions.

AIM

The objective of this study is to identify endothelial functions of the pro-hypertrophic miR-212/132 cluster and its cross-talk with other microRNAs during development and disease.

METHODS AND RESULTS

We here show that anti-angiogenic stimulation by transforming growth factor-beta activates the microRNA-212/132 cluster by derepression of their transcriptional co-activator cAMP response element-binding protein (CREB)-binding protein (CBP) which is a novel target of a previously identified pro-angiogenic miRNA miR-30a-3p in endothelial cells. Surprisingly, despite having the same seed-sequence, miR-212 and miR-132 exerted differential effects on endothelial transcriptome regulation and cellular functions with stronger endothelial inhibitory effects caused by miR-212. These differences could be attributed to additional auxiliary binding of miR-212 to its targets. In vivo, deletion of the miR-212/132 cluster increased endothelial vasodilatory function, improved angiogenic responses during postnatal development and in adult mice.

CONCLUSION

Our results identify (i) a novel miRNA-cross-talk involving miR-30a-3p and miR-212, which led to suppression of important endothelial genes such as GAB1 and SIRT1 finally culminating in impaired endothelial function; and (ii) microRNAs may have different biological roles despite having the same seed sequence.

MicroRNAs in right ventricular (dys)function (2013 Grover Conference series)

MicroRNAs (miRNAs) are molecules increasingly investigated for both diagnostic and therapeutic strategies. Whereas information about their role in the left ventricle has been studied for many years, there is scarce information about the right ventricle. We thus here review known details about the expression, regulation, and function of miRNAs in right heart diseases. Current identified therapeutic strategies using miRNA modulators to treat pulmonary hypertension and thus also having beneficial effects on the right ventricle are also discussed. Finally, the current knowledge about the diagnostic and predictive use of circulating miRNAs in patients with pulmonary hypertension and right ventricular failure is presented. There is strong hope that the increasing knowledge about miRNAs in the right heart will finally help to improve the treatment of patients with pulmonary and right ventricular heart diseases.

Cardiac fibroblast-derived microRNA passenger strand-enriched exosomes mediate cardiomyocyte hypertrophy

In response to stress, the heart undergoes extensive cardiac remodeling that results in cardiac fibrosis and pathological growth of cardiomyocytes (hypertrophy), which contribute to heart failure. Alterations in microRNA (miRNA) levels are associated with dysfunctional gene expression profiles associated with many cardiovascular disease conditions; however, miRNAs have emerged recently as paracrine signaling mediators. Thus, we investigated a potential paracrine miRNA crosstalk between cardiac fibroblasts and cardiomyocytes and found that cardiac fibroblasts secrete miRNA-enriched exosomes. Surprisingly, evaluation of the miRNA content of cardiac fibroblast-derived exosomes revealed a relatively high abundance of many miRNA passenger strands ("star" miRNAs), which normally undergo intracellular degradation. Using confocal imaging and coculture assays, we identified fibroblast exosomal-derived miR-21_3p (miR-21*) as a potent paracrine-acting RNA molecule that induces cardiomyocyte hypertrophy. Proteome profiling identified sorbin and SH3 domain-containing protein 2 (SORBS2) and PDZ and LIM domain 5 (PDLIM5) as miR-21* targets, and silencing SORBS2 or PDLIM5 in cardiomyocytes induced hypertrophy. Pharmacological inhibition of miR-21* in a mouse model of Ang II-induced cardiac hypertrophy attenuated pathology. These findings demonstrate that cardiac fibroblasts secrete star miRNA-enriched exosomes and identify fibroblast-derived miR-21* as a paracrine signaling mediator of cardiomyocyte hypertrophy that has potential as a therapeutic target.

Regulation of cardiac and renal ischemia-reperfusion injury by microRNAs

Tissue damage caused by ischemia-reperfusion (I/R) injury represents a serious event, which often leads to deterioration or even loss of organ function. I/R injury is associated with transient tissue oxygen deprivation due to vessel occlusion and a subsequent reperfusion period following restoration of blood flow. Initial tissue damage inflicted by ischemia is aggravated in the reperfusion period through mechanisms such as burst of reactive oxygen and nitrogen species and inflammatory reactions. I/R injury occurs during surgical interventions, organ transplantation, diseases such as myocardial infarction, circulatory shock, and toxic insults. Recently, microRNAs have come into focus as powerful regulators of gene expression and potential diagnostic tools during I/R injury. These small noncoding ribonucleotides (~22 nucleotides in length) posttranscriptionally target mRNAs, culminating in suppression of protein synthesis or increase in mRNA degradation, thus fundamentally influencing organ function. This review highlights the latest developments regarding the role of microRNAs in cardiac and renal I/R injury.

MicroRNA-mediated epigenetic silencing of sirtuin1 contributes to impaired angiogenic responses

RATIONALE

Transforming growth factor (TGF)-β was linked to abnormal vessel function and can mediate impairment of endothelial angiogenic responses. Its effect on microRNAs and downstream targets in this context is not known.

OBJECTIVE

To study the role of microRNAs in TGF-β-mediated angiogenic activity.

METHODS AND RESULTS

MicroRNA profiling after TGF-β treatment of endothelial cells identified miR-30a-3p, along with other members of the miR-30 family, to be strongly silenced. Supplementation of miR-30a-3p restored function in TGF-β-treated endothelial cells. We identified the epigenetic factor methyl-CpG-binding protein 2 (MeCP2) to be a direct and functional target of miR-30a-3p. Viral overexpression of MeCP2 mimicked the effects of TGF-β, suggesting that derepression of MeCP2 after TGF-β treatment may be responsible for impaired angiogenic responses. Silencing of MeCP2 rescued detrimental TGF-β effects on endothelial cells. Microarray transcriptome analysis of MeCP2-overexpressing endothelial cells identified several deregulated genes important for endothelial cell function including sirtuin1 (Sirt1). In vivo experiments using endothelial cell-specific MeCP2 null or Sirt1 transgenic mice confirmed the involvement of MeCP2/Sirt1 in the regulation of angiogenic functions of endothelial cells. Additional experiments identified that MeCP2 inhibited endothelial angiogenic characteristics partly by epigenetic silencing of Sirt1.

CONCLUSIONS

TGF-β impairs endothelial angiogenic responses partly by downregulating miR-30a-3p and subsequent derepression of MeCP2-mediated epigenetic silencing of Sirt1.

Stable isotope liquid chromatography-tandem mass spectrometry assay for fatty acid amide hydrolase activity

Fatty acid amide hydrolase (FAAH) is the main enzyme responsible for the hydrolysis of the endocannabinoid anandamide (arachidonoyl ethanolamide, AEA) to arachidonic acid (AA) and ethanolamine (EA). Published FAAH activity assays mostly employ radiolabeled anandamide or synthetic fluorogenic substrates. We report a stable isotope liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for specific, sensitive, and high-throughput capable FAAH activity measurements. The assay uses AEA labeled with deuterium on the EA moiety (d₄-AEA) as substrate and measures the specific reaction product tetradeutero-EA (d₄-EA) and the internal standard ¹³C₂-EA. Selected reaction monitoring of m/z 66→m/z 48 (d₄-EA) and m/z 64→m/z 46 (¹³C₂-EA) in the positive electrospray ionization mode after liquid chromatographic separation on a HILIC (hydrophilic interaction liquid chromatography) column is performed. The assay was developed and thoroughly validated using recombinant human FAAH (rhFAAH) and then was applied to human blood and dog liver samples. rhFAAH-catalyzed d₄-AEA hydrolysis obeyed Michaelis-Menten kinetics (K(M)=12.3 μM, V(max)=27.6 nmol/min mg). Oleoyl oxazolopyridine (oloxa) was a potent, partial noncompetitive inhibitor of rhFAAH (IC₅₀=24.3 nM). Substrate specificity of other fatty acid ethanolamides decreased with decreasing length, number of double bonds, and lipophilicity of the fatty acid skeleton. In human whole blood, we detected FAAH activity that was inhibited by oloxa.

Simultaneous UPLC-MS/MS quantification of the endocannabinoids 2-arachidonoyl glycerol (2AG), 1-arachidonoyl glycerol (1AG), and anandamide in human plasma: minimization of matrix-effects, 2AG/1AG isomerization and degradation by toluene solvent extraction

Analysis of the endocannabinoid (EC) system's key molecules 2-arachidonoyl glycerol (2AG) and arachidonoyl ethanolamide (anandamide, AEA) is challenging due to several peculiarities. 2AG isomerizes spontaneously to its biologically inactive analogue 1-arachidonoyl glycerol (1AG) by acyl migration and it is only chromatographically distinguishable from 1AG. Matrix-effects caused primarily by co-extracted phospholipids may further compromise analysis. In addition, 2AG and 1AG are unstable under certain conditions like solvent evaporation or reconstitution of dried extracts. We examined effects of different organic solvents and their mixtures, such as toluene, ethyl acetate, and chloroform-methanol, on 2AG/1AG isomerisation, 2AG/1AG stability, and matrix-effects in the UPLC-MS/MS analysis of 2AG and AEA in human plasma. Toluene prevented, both, 2AG isomerisation to 1AG and degradation of 2AG/1AG during evaporation. Toluene extracts contain only 2% of matrix-effect-causing plasma phospholipids compared to extracts from the traditionally used solvent mixture chloroform-methanol. Toluene and all other tested organic solvents provide comparable 2AG and AEA extraction yields (60-80%). Based on these favourable toluene properties, we developed and validated a UPLC-MS/MS method with positive electrospray ionization (ESI+) that allows for simultaneous accurate and precise measurement of 2AG and AEA in human plasma. The UPLC-MS/MS method was cross-validated with a previously described fully-validated GC-MS/MS method for AEA in human plasma. A close correlation (r(2)=0.821) was observed between the results obtained from UPLC-MS/MS (y) and GC-MS/MS (x) methods (y=0.01+0.85x). The UPLC-MS/MS method is suitable for routine measurement of 2AG and AEA in human plasma samples (1 mL) in clinical settings as shown by quality control plasma samples processed over a period of 100 days. The UPLC-MS/MS method was further extended to human urine. In urine, AEA was not detectable and 2AG was detected in only 3 out of 19 samples from healthy subjects at 160, 180 and 212 pM corresponding to 12.3, 14.5 and 9.9 pmol/mmol creatinine, respectively.

Measurement and diagnostic use of hepatic cytochrome P450 metabolism of oleic acid in liver disease

BACKGROUND

Oleic acid is a major systemically circulating fatty acid in humans with atheroprotective and immunomodulatory properties. As of today, the contribution of individual cytochrome P450 (CYP) mono-oxygenases to the epoxidation of this fatty acid is unknown. Furthermore, the extent of the oleic acid oxidation product cis-9,10-epoxyoctadecanoic acid (cis-EODA) in humans and its plasma levels in patients with impaired liver function are not known.

PATIENTS AND METHODS

We studied cis-EODA in plasma of patients suffering from chronic liver diseases, a condition that often displays impaired liver CYP enzyme activities. Fifteen CYP mono-oxygenases were investigated in vitro as a potential source of cis-EODA.

RESULTS

Strikingly, plasma levels of cis-EODA were significantly repressed (P<0.0005) when patients with liver impairment (n=16) were compared with healthy subjects (n=14). Production of cis-EODA was catalysed by CYP in the following order: 2C8, 2C9, 2C19, 3A4, 1A2 and CYP3A7.

CONCLUSION

cis-EODA plasma concentrations are decreased in hepatic disease with impaired liver function. Oleic acid is primarily oxidized to oleic acid oxide (cis-EODA) by CYP2C and CYP3A mono-oxygenases. The liver is the major organ responsible for the oxidation of oleic acid to cis-EODA, and thus, cis-EODA may be a suitable biomarker to assess liver function.