Longitudinal characterization of clinically relevant haemodynamics in conscious Ossabaw pigs with HFpEF

Background

The constantly growing population of patients suffering from heart failure with preserved ejection fraction (HFpEF) is one of the largest unmet needs in cardiovascular medicine and translational animal models are important for identification and profiling of novel therapeutic approaches. Large animal models have shown that chronic cardiac pressure overload by aortic banding (AoB), when combined with a Western diet leads to left ventricular hypertrophy, diastolic dysfunction and metabolic syndrome in the Ossabaw pig, reflecting important features of human HFpEF characteristics. However, the requirement of invasive diagnostics under anaesthesia often limits the ability to monitor disease development continuously and compromises the results. Therefore, current disease models lack the temporal progression of clinically relevant HFpEF parameters like the left ventricular end diastolic pressure (LVEDP) and time constant of left ventricular relaxation (Tau).

Purpose

We aim to non-invasively investigate disease progression in Ossabaw pigs exhibiting a cardiometabolic HFpEF phenotype. The longitudinal assessment of LVEDP, Tau and heart rate (HR) should identify a time window to test novel therapeutics.

Methods

Naive, female Ossabaw pigs were instrumented with telemetric devices followed by AoB to induce chronic cardiac pressure overload. The wound healing and acclimatization period was followed by the start of a Western diet feeding regime to mimic components of the metabolic syndrome. Disease progression was characterized over 9 months by monthly telemetric recordings of LVEDP, Tau and HR and compared to a control (Ctrl) measurement in healthy animals. All animal studies followed the `Principles of laboratory animal care'.

Results

Compared to Ctrl the LVEDP is significantly elevated already 1 month (+8.90±0.4 mmHg) after AoB and further increases over time until 8 months (+18.80±0.4 mmHg) post AoB. Significant elevations in Tau are evident 4 months (+1.61±0.4 ms) post AoB. After 1 month the HR is significantly elevated (+13.90±0.7 bpm) but tends to normalize between 5 to 7 months post AoB. After AoB a maximal relative increase in LVEDP (+5.12±0.4 mmHg), Tau (+5.04±0.4 ms) and HR (+16.90±0.7 bpm) can be observed after 8 months.

Conclusions

We present long term haemodynamic changes over time in a translational in vivo model for HFpEF in Ossabaw pigs with high temporal resolution. For the first time elevations in key parameters allow to set a time point where HFpEF characteristics are evident, and a drug testing regime could be started. The opportunity to non-invasively and longitudinally follow on LVEDP, Tau and HR will be a clear benefit in the development of novel treatment options for HFpEF.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Bayer AG, Wuppertal

Dissecting the transcriptome in cardiovascular disease

The human transcriptome comprises a complex network of coding and non-coding RNAs implicated in a myriad of biological functions. Non-coding RNAs exhibit highly organized spatial and temporal expression patterns and are emerging as critical regulators of differentiation, homeostasis, and pathological states, including in the cardiovascular system. This review defines the current knowledge gaps, unmet methodological needs, and describes the challenges in dissecting and understanding the role and regulation of the non-coding transcriptome in cardiovascular disease. These challenges include poor annotation of the non-coding genome, determination of the cellular distribution of transcripts, assessment of the role of RNA processing and identification of cell-type specific changes in cardiovascular physiology and disease. We highlight similarities and differences in the hurdles associated with the analysis of the non-coding and protein-coding transcriptomes. In addition, we discuss how the lack of consensus and absence of standardized methods affect reproducibility of data. These shortcomings should be defeated in order to make significant scientific progress and foster the development of clinically applicable non-coding RNA-based therapeutic strategies to lessen the burden of cardiovascular disease.

Chemical and mechanical activation of resident cardiac macrophages in the living myocardial slice ex vivo model

Resident cardiac macrophages (rcMACs) are among the most abundant immune cells in the heart. Plasticity and activation are hallmarks of rcMACs in response to changes in the microenvironment, which is essential for in vitro experimentation. The in vivo investigation is confounded by the infiltration of other cells hindering direct studies of rcMACs. As a tool to investigate rcMACs, we applied the ex vivo model of living myocardial slices (LMS). LMS are ultrathin ex vivo multicellular cardiac preparations in which the circulatory network is interrupted. The absence of infiltration in this model enables the investigation of the rcMACs response to immunomodulatory and mechanical stimulations. Such conditions were generated by applying interferon-gamma (IFN-γ) or interleukine-4 (IL-4) and altering the preload of cultured LMS, respectively. The immunomodulatory stimulation of the LMS induced alterations of the gene expression pattern without affecting tissue contractility. Following 24 h culture, low input RNA sequencing of rcMACs isolated from LMS was used for gene ontology analysis. Reducing the tissue stretch (unloading) of LMS altered the gene ontology clusters of isolated rcMACs with intermediate semantic similarity to IFN-γ triggered reaction. Through the overlap of genes affected by IFN-γ and unloading, we identified Allograft inflammatory factor 1 (AIF-1) as a potential marker gene for inflammation of rcMACs as significantly altered in whole immunomodulated LMS. MicroRNAs associated with the transcriptomic changes of rcMACs in unloaded LMS were identified in silico. Here, we demonstrate the approach of LMS to understand load-triggered cardiac inflammation and, thus, identify potential translationally important therapeutic targets.

Diagnostic value of circulating microRNAs compared to high-sensitivity troponin T for the detection of non-ST-segment elevation myocardial infarction

Background/Introduction

MicroRNAs (miRNAs) are promising biomarkers due to their high specificity and may facilitate differential diagnosis of patients presenting with suspected acute coronary syndrome (ACS) to the emergency department (ED).

Purpose

To assess the diagnostic value of eleven miRNAs for the detection of non-ST-segment elevation myocardial infarction (NSTEMI).

Methods

1,042 patients presenting between August 2014 and April 2017 to the ED with suspected ACS were included. NSTEMI was diagnosed per criteria of the 4th Universal definition of myocardial infarction (UDMI) using high-sensitivity troponin T (hs-cTnT). Expression levels of eleven microRNAs (miR-21, miR-22, miR-29a, miR-92a, miR-122, miR-126, miR-132, miR-133, miR-134, miR-191, miR-423) were determined using RT-qPCR. Discrimination of NSTEMI was assessed for individual and a panel of miRNAs compared to the hs-cTnT reference using C-statistics and reclassification analysis.

Results

NSTEMI was diagnosed in 137 (13.1%) patients. The AUC of the hs-cTnT based reference was 0.937. In a multivariate model three miRNAs (miR-122, miR-133 and miR-134) were found to be associated with NSTEMI with AUCs between 0.506 and 0.656. A panel consisting of these miRNAs revealed an AUC of 0.662 for the diagnosis of NSTEMI. The AUC of the combination of the miRNA panel and troponin reference was significantly lower than the reference standard (AUC: 0.897 vs. 0.937, p=0.006). Despite a significant improvement of NSTEMI reclassification measured by IDI and NRI, miRNAs did not improve specificity of hs-cTnT kinetic changes for the diagnosis of NSTEMI (ΔAUC: 0.04).

Conclusion

Although single miRNAs are significantly associated with the diagnosis of NSTEMI a miRNA panel does not add diagnostic accuracy to the hs-cTnT reference considering baseline values and kinetic changes as recommended by 4th version of UDMI.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): German Heart Foundation/German Foundation of Heart Research.CIBERES (CB07/06/2008 to DdGC) is a project from Carlos III Health Institute. Central illustration

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

Resident cardiac macrophages: crucial modulators of cardiac (patho)physiology

Resident cardiac macrophages (rcMacs) are integral components of the myocardium where they have key roles for tissue homeostasis and in response to inflammation, tissue injury and remodelling. In this review, we summarize the current knowledge and limitations associated with the rcMacs studies. We describe their specific role and contribution in various processes such as electrical conduction, efferocytosis, inflammation, tissue development, remodelling and regeneration in both the healthy and the disease state. We also outline research challenges and technical complications associated with rcMac research. Recent technological developments and contemporary immunological techniques are now offering new opportunities to investigate the separate contribution of rcMac in respect to recruited monocytes and other cardiac cells. Finally, we discuss new therapeutic strategies, such as drugs or non-coding RNAs, which can influence rcMac phenotype and their response to inflammation. These novel approaches will allow for a deeper understanding of this cardiac endogenous cell type and might lead to the development of more specific and effective therapeutic strategies to boost the heart's intrinsic reparative capacity.

A practical guide for investigating cardiac physiology using living myocardial slices

Ex vivo multicellular preparations are essential tools to study tissue physiology. Among them, the recent methodological and technological developments in living myocardial slices (LMS) are attracting increasing interest by the cardiac research field. Despite this, this research model remains poorly perceived and utilized by most research laboratories. Here, we provide a practical guide on how to use LMS to interrogate multiple aspects of cardiac function, structure and biochemistry. We discuss issues that should be considered to conduct successful experiments, including experimental design, sample preparation, data collection and analysis. We describe how laboratory setups can be adapted to accommodate and interrogate this multicellular research model. These adaptations can often be achieved at a reasonable cost with off-the-shelf components and operated reliably using well-established protocols and freely available software, which is essential to broaden the utilization of this method. We will also highlight how current measurements can be improved to further enhance data quality and reliability to ensure inter-laboratory reproducibility. Finally, we summarize the most promising biomedical applications and envision how living myocardial slices can lead to further breakthroughs.

[Non-coding RNA : Innovative regulators with therapeutic perspective]

As a result of the Human Genome Project it became evident that only 1-3% of all gene transcripts encode proteins. The vast majority of gene transcripts are in fact characterized as non-coding RNAs (ncRNAs). These ncRNAs have a huge impact on diverse physiological and pathological mechanisms within an organism. In particular, microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), which are differentiated by their size and function, are involved in the regulation and development of many illnesses. In the context of heart and cardiovascular diseases numerous ncRNAs have also already been described in some detail. As these molecules represent therapeutic target structures, ncRNAs provide a completely new level for the discovery of promising therapeutic approaches. Many approaches have already been developed aimed at influencing the expression levels of specific ncRNAs in order to induce beneficial effects on pathological processes. In fact, first medications based on miRNAs have already achieved approval. Additionally, ncRNAs contained in plasma can serve as new non-invasive diagnostic markers for the detection of diseases.

microRNA-206 correlates with left ventricular function after transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is the method of choice in patients with high risk or contraindications for conventional aortic valve replacement. However, it is not well understood which parameters predict the overall cardiac function postprocedurally. miRNAs are small noncoding RNA molecules that repress gene expression by different mechanisms and can also be detected in the blood. Recent studies have shown that miRNAs detected in the blood may serve as sensitive and specific biomarkers in various diseases; therefore, we examined the levels of different microRNAs in the serum of patients undergoing TAVI. We thereby intended to find potential predictors for cardiac function after TAVI. Serum from patients with aortic valve disease was obtained at five different points: before the TAVI procedure, at days 1 and 3 after the TAVI procedure, and the day of dischargement and after a period of 3 mo. We next performed quantitative real-time PCRs to examine the samples for changes in the level of miRNAs previously described as cardiac enriched. Our results show that the level of miR-206 in the serum of patients after TAVI correlated negatively with the left ventricular ejection fraction of individual patients. We found left ventricular function to be better in patients with lower levels of miR-206 after implantation of the new valve. A decrease in the serum level of miR-206 may be linked to changes in cardiac function of patients after TAVI. Further studies are necessary to test the miRNA for its potential value as a prognostic marker. NEW & NOTEWORTHY This study is the first to investigate novel miRNA-based biomarkers within the context of transcatheter aortic valve implantation. miRNA-206 proved to correlate inversely with the postprocedural left ventricular ejection fraction of patients.

The XIIIth Banff Conference on Allograft Pathology: The Banff 2015 Heart Meeting Report: Improving Antibody-Mediated Rejection Diagnostics: Strengths, Unmet Needs, and Future Directions

The 13th Banff Conference on Allograft Pathology was held in Vancouver, British Columbia, Canada from October 5 to 10, 2015. The cardiac session was devoted to current diagnostic issues in heart transplantation with a focus on antibody-mediated rejection (AMR) and small vessel arteriopathy. Specific topics included the strengths and limitations of the current rejection grading system, the central role of microvascular injury in AMR and approaches to semiquantitative assessment of histopathologic and immunophenotypic indicators, the role of AMR in the development of cardiac allograft vasculopathy, the important role of serologic antibody detection in the management of transplant recipients, and the potential application of new molecular approaches to the elucidation of the pathophysiology of AMR and potential for improving the current diagnostic system. Herein we summarize the key points from the presentations, the comprehensive, open and wide-ranging multidisciplinary discussion that was generated, and considerations for future endeavors.

Circulating long-non coding RNAs as biomarkers of left ventricular diastolic function and remodelling in patients with well-controlled type 2 diabetes

Contractile dysfunction is underdiagnosed in early stages of diabetic cardiomyopathy. We evaluated the potential of circulating long non-coding RNAs (lncRNAs) as biomarkers of subclinical cardiac abnormalities in type 2 diabetes. Forty-eight men with well-controlled type 2 diabetes and 12 healthy age-matched volunteers were enrolled in the study. Left ventricular (LV) parameters were measured by magnetic resonance imaging. A panel of lncRNAs was quantified in serum by RT-qPCR. No differences in expression levels of lncRNAs were observed between type 2 diabetes patients and healthy volunteers. In patients with type 2 diabetes, long intergenic non-coding RNA predicting cardiac remodeling (LIPCAR) was inversely associated with diastolic function, measured as E/A peak flow (P < 0.050 for all linear models). LIPCAR was positively associated with grade I diastolic dysfunction (P < 0.050 for all logistic models). Myocardial infarction-associated transcript (MIAT) and smooth muscle and endothelial cell-enriched migration/differentiation-associated long noncoding RNA (SENCR) were directly associated with LV mass to LV end-diastolic volume ratio, a marker of cardiac remodelling (P < 0.050 for all linear models). These findings were validated in a sample of 30 patients with well-controlled type 2 diabetes. LncRNAs are independent predictors of diastolic function and remodelling in patients with type 2 diabetes.

RNA Profiling in Human and Murine Transplanted Hearts: Identification and Validation of Therapeutic Targets for Acute Cardiac and Renal Allograft Rejection

Acute cellular rejection (ACR) is the adverse response of the recipient's immune system against the allogeneic graft. Using human surveillance endomyocardial biopsies (EMBs) manifesting ACR and murine allogeneic grafts, we profiled implicated microRNAs (miRs) and mRNAs. MiR profiling showed that miR-21, -142-3p, -142-5p, -146a, -146b, -155, -222, -223, and -494 increased during ACR in humans and mice, whereas miR-149-5p decreased. mRNA profiling revealed 70 common differentially regulated transcripts, all involved in immune signaling and immune-related diseases. Interestingly, 33 of 70 transcripts function downstream of IL-6 and its transcription factor spleen focus forming virus proviral integration oncogene (SPI1), an established target of miR-155, the most upregulated miR in human EMBs manifesting rejection. In a mouse model of cardiac transplantation, miR-155 absence and pharmacological inhibition attenuated ACR, demonstrating the causal involvement and therapeutic potential of miRs. Finally, we corroborated our miR signature in acute cellular renal allograft rejection, suggesting a nonorgan specific signature of acute rejection. We concluded that miR and mRNA profiling in human and murine ACR revealed the shared significant dysregulation of immune genes. Inflammatory miRs, for example miR-155, and transcripts, in particular those related to the IL-6 pathway, are promising therapeutic targets to prevent acute allograft rejection.

Detection and transport mechanisms of circulating microRNAs in neurological, cardiac and kidney diseases

MicroRNAs are small non-coding RNA transcripts that modulate gene expression and translation through target mRNA destabilization and/or inhibition of protein synthesis. Various studies have aimed at elucidation of the role of these small molecules in the regulation of disease activity. Initially, microRNA were believed to merely act as intracellular mediators fine-tuning mRNA translation into proteins. Recently, the first studies have emerged demonstrating that microRNAs are also externalized from cells and transported in body fluids, thereby shuttling genetic information from a donor to a recipient cell. Thus, circulating microRNAs represent attractive non-invasive detectable markers to monitor onset/ progress of diseases. The present article outlines the quantification and biomarker use of microRNAs in various body fluids of patients with cardiac and kidney disease as well as neurological disorders.

MicroRNAs in platelet physiology and pathology

MicroRNAs (miRNAs), highly conserved, short (approx. 22 nucleotides) non-coding RNAs, exhibit a fine-tune control over gene expression by complementary sequence binding and translational repression of protein coding mRNA transcripts. Recently, the role of miRNAs has been increasingly investigated in various physiological or pathophysiological events. Circulating platelets are crucial for coagulation physiology to maintain haemostatic balance and are involved in various pathologies such as atherosclerosis and thrombosis. Anucleate platelets lack genomic DNA but inherit diverse array of functional coding or non-coding RNAs and translational machinery from their parent cells - megakaryocytes enabling activated platelets to synthesize proteins which suggests the possibility of post transcriptional gene regulation in platelets. Expression of functionally active miRNAs in platelets changes during platelet activation indicating a role in platelet biology. Here, we present a review on recently identified platelet miRNAs and their role in platelet physiology that is essential for maintaining haemostasis.

Microvesicles as novel biomarkers and therapeutic targets in transplantation medicine

Microvesicles (MVs) including exosomes are emerging new biomarkers and potential regulators of inflammation and immunological processes. Such particles contain proteins and genetic information including DNA and microRNAs that may be of importance for cell/cell communication. However, their role during and after organ transplantation and immunomodulatory effects is only in its beginning of understanding. We here, in brief, introduce generation and biological importance of MVs, describe their (patho)physiological roles and their potential use as future biomarkers and therapeutic agents in transplantation medicine. Circulating MVs may have a great potential to detect possible immune rejections and MV modulation may emerge as a therapeutic approach in organ rejection therapy.

Novel techniques and targets in cardiovascular microRNA research

MicroRNAs (miRNAs) are highly conserved, tiny (∼22 nucleotides) non-coding RNAs that have emerged as potent regulators of mRNA translation. miRNAs exhibit fine-tuning of the control of proteins involved in cell signalling (AE) pathways and in vital cellular and developmental processes. miRNAs are expressed in cardiovascular tissues, and multiple functional aspects of miRNAs underscore their key role in cardiovascular (patho)physiology. The development and increasing use of novel molecular biology tools have contributed to the recent success in miRNA research. In the present review, we discuss current updates on important and novel miRNA techniques, including: (i) miRNA screening tools; (ii) bioanalytical target prediction tools; (iii) target validation tools; and (iv) manipulative miRNA expression tools. We also present an update about recently identified miRNA targets that play a key role in cardiovascular development and disorders.