Showing papers by "Benjamin Meder published in 2019"

Regional Variation in RBM20 Causes a Highly Penetrant Arrhythmogenic Cardiomyopathy

Abstract: Background Variants in the cardiomyocyte-specific RNA splicing factor RBM20 have been linked to familial cardiomyopathy, but the causative genetic architecture and clinical consequences of this disease are incompletely defined. Methods and Results To define the genetic architecture of RBM20 cardiomyopathy, we first established a database of RBM20 variants associated with cardiomyopathy and compared these to variants observed in the general population with respect to their location in the RBM20 coding transcript. We identified 2 regions significantly enriched for cardiomyopathy-associated variants in exons 9 and 11. We then assembled a registry of 74 patients with RBM20 variants from 8 institutions across the world (44 index cases and 30 from cascade testing). This RBM20 patient registry revealed highly prevalent family history of sudden cardiac death (51%) and cardiomyopathy (72%) among index cases and a high prevalence of composite arrhythmias (including atrial fibrillation, nonsustained ventricular tachycardia, implantable cardiac defibrillator discharge, and sudden cardiac arrest, 43%). Patients harboring variants in cardiomyopathy-enriched regions identified by our variant database analysis were enriched for these findings. Further, these characteristics were more prevalent in the RBM20 registry than in large cohorts of patients with dilated cardiomyopathy and TTNtv cardiomyopathy and not significantly different from a cohort of patients with LMNA-associated cardiomyopathy. Conclusions Our data establish RBM20 cardiomyopathy as a highly penetrant and arrhythmogenic cardiomyopathy. These findings underline the importance of arrhythmia surveillance and family screening in this disease and represent the first step in defining the genetic architecture of RBM20 disease causality on a population level.

Immune system-mediated atherosclerosis caused by deficiency of long non-coding RNA MALAT1 in ApoE-/-mice.

Abstract: Aims The immune system is considered a key driver of atherosclerosis, and beyond proteins and microRNAs (miRs), long non-coding RNAs (lncRNAs) are implicated in immune control. We previously described that lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in cardiac innate immunity in a myocarditis model. Here, we investigated the impact of MALAT1 deficiency upon atherosclerosis development. Methods and results Heterozygous MALAT1-deficient ApoE-/- mice displayed massive immune system dysregulation and atherosclerosis within 2 months even when kept on normal diet. Aortic plaque area (P < 0.05) and aortic root plaque size (P < 0.001) were increased in MALAT1-deficient vs. MALAT1-wildtype ApoE-/- mice. Serum levels of interferon-γ (IFN-γ), tumour necrosis factor (TNF), and interleukin 6 (IL6) were elevated (P < 0.001) in MALAT1-deficient animals. MALAT1-deficient bone marrow-derived macrophages showed enhanced expression of TNF (P = 0.001) and inducible NO synthase (NOS2) (P = 0.002), suppressed MMP9 (P < 0.001), and impaired phagocytic activity (P < 0.001) upon lipopolysaccharide stimulation. RNA-sequencing revealed grossly altered transcriptomes of MALAT1-deficient splenocytes already at baseline, with massive induction of IFN- γ, TNF, NOS2, and granzyme B; CC and CXC chemokines and CCR8; and innate immunity genes interferon-induced protein with tetratricopeptide repeats (IFIT)1/3, interferon-induced transmembrane protein (IFITM)1/3, ISG15. Multiple miRs were up to 45-fold upregulated. Further, selective ablation of the cytosolic part of the MALAT1 system only, the enzymatically MALAT1-derived mascRNA, resulted in massive induction of TNF (P = 0.004) and IL6 (P = 0.028) in macrophages. Northern analysis of post-myocardial infarction patient vs. control peripheral blood mononuclear cells showed reduced (P = 0.005) mascRNA in the patients. CHART-enriched RNA-sequencing reads at the genomic loci of MALAT1 and neighbouring nuclear enriched abundant transcript (NEAT1) documented direct interaction between these lncRNA transcripts. Conclusion The data suggest a molecular circuit involving the MALAT1-mascRNA system, interactions between MALAT1 and NEAT1, and key immune effector molecules, cumulatively impacting upon the development of atherosclerosis. It appears reasonable to look for therapeutic targets in this circuit and to screen for anomalies in the NEAT1-MALAT1 region in humans, too, as possible novel disease risk factors.

Long noncoding RNA NEAT1 modulates immune cell functions and is suppressed in early onset myocardial infarction patients.

Abstract: AIMS Inflammation is a key driver of atherosclerosis and myocardial infarction (MI), and beyond proteins and microRNAs (miRs), long noncoding RNAs (lncRNAs) have been implicated in inflammation control. To obtain further information on the possible role of lncRNAs in the context of atherosclerosis, we obtained comprehensive transcriptome maps of circulating immune cells (peripheral blood mononuclear cells, PBMCs) of early onset MI patients. One lncRNA significantly suppressed in post-MI patients was further investigated in a murine knockout model. METHODS AND RESULTS Individual RNA-sequencing (RNA-seq) was conducted on PBMCs from 28 post-MI patients with a history of MI at age ≤50 years and stable disease ≥3 months before study participation, and from 31 healthy individuals without manifest cardiovascular disease or family history of MI as controls. RNA-seq revealed deregulated protein-coding transcripts and lncRNAs in post-MI PBMCs, among which nuclear enriched abundant transcript (NEAT1) was the most highly expressed lncRNA, and the only one significantly suppressed in patients. Multivariate statistical analysis of validation cohorts of 106 post-MI patients and 85 controls indicated that the PBMC NEAT1 levels were influenced (P = 0.001) by post-MI status independent of statin intake, left ventricular ejection fraction, low-density lipoprotein or high-density lipoprotein cholesterol, or age. We investigated NEAT1-/- mice as a model of NEAT1 deficiency to evaluate if NEAT1 depletion may directly and causally alter immune regulation. RNA-seq of NEAT1-/- splenocytes identified disturbed expression and regulation of chemokines/receptors, innate immunity genes, tumour necrosis factor (TNF) and caspases, and increased production of reactive oxygen species (ROS) under baseline conditions. NEAT1-/- spleen displayed anomalous Treg and TH cell differentiation. NEAT1-/- bone marrow-derived macrophages (BMDMs) displayed altered transcriptomes with disturbed chemokine/chemokine receptor expression, increased baseline phagocytosis (P < 0.0001), and attenuated proliferation (P = 0.0013). NEAT1-/- BMDMs responded to LPS with increased (P < 0.0001) ROS production and disturbed phagocytic activity (P = 0.0318). Monocyte-macrophage differentiation was deregulated in NEAT1-/- bone marrow and blood. NEAT1-/- mice displayed aortic wall CD68+ cell infiltration, and there was evidence of myocardial inflammation which could lead to severe and potentially life-threatening structural damage in some of these animals. CONCLUSION The study indicates distinctive alterations of lncRNA expression in post-MI patient PBMCs. Regarding the monocyte-enriched NEAT1 suppressed in post-MI patients, the data from NEAT1-/- mice identify NEAT1 as a novel lncRNA-type immunoregulator affecting monocyte-macrophage functions and T cell differentiation. NEAT1 is part of a molecular circuit also involving several chemokines and interleukins persistently deregulated post-MI. Individual profiling of this circuit may contribute to identify high-risk patients likely to benefit from immunomodulatory therapies. It also appears reasonable to look for new therapeutic targets within this circuit.

Clinical and genetic insights into non-compaction: a meta-analysis and systematic review on 7598 individuals

Abstract: Left ventricular non-compaction has been increasingly diagnosed in recent years. However, it is still debated whether non-compaction is a pathological condition or a physiological trait. In this meta-analysis and systematic review, we compare studies, which investigated these two different perspectives. Furthermore, we provide a comprehensive overview on the clinical outcome as well as genetic background of left ventricular non-compaction cardiomyopathy in adult patients. We retrieved PubMed/Medline literatures in English language from 2000 to 19/09/2018 on clinical outcome and genotype of patients with non-compaction. We summarized and extensively reviewed all studies that passed selection criteria and performed a meta-analysis on key phenotypic parameters. Altogether, 35 studies with 2271 non-compaction patients were included in our meta-analysis. The mean age at diagnosis was the mid of their fifth decade. Two-thirds of patients were male. Congenital heart diseases including atrial or ventricular septum defect or Ebstein anomaly were reported in 7% of patients. Twenty-four percent presented with family history of cardiomyopathy. The mean frequency of neuromuscular diseases was 5%. Heart rhythm abnormalities were reported frequently: conduction disease in 26%, supraventricular tachycardia in 17%, and sustained or non-sustained ventricular tachycardia in 18% of patients. Three important outcome measures were reported including systemic thromboembolic events with a mean frequency of 9%, heart transplantation with 4%, and adequate ICD therapy with 15%. Nine studies investigated the genetics of non-compaction cardiomyopathy. The most frequently mutated gene was TTN with a pooled frequency of 11%. The average frequency of MYH7 mutations was 9%, for MYBPC3 mutations 5%, and for CASQ2 and LDB3 3% each. TPM1, MIB1, ACTC1, and LMNA mutations had an average frequency of 2% each. Mutations in PLN, HCN4, TAZ, DTNA, TNNT2, and RBM20 were reported with a frequency of 1% each. We also summarized the results of eight studies investigating the non-compaction in altogether 5327 athletes, pregnant women, patients with sickle cell disease, as well as individuals from population-based cohorts, in which the presence of left ventricular hypertrabeculation ranged from 1.3 to 37%. The summarized data indicate that non-compaction may lead to unfavorable outcome in different cardiomyopathy entities. The presence of key features in a multimodal diagnostic approach could distinguish between benign morphological trait and manifest cardiomyopathy.

Diagnostik und Therapie der kardialen Amyloidose

Abstract: Systemische Amyloidoseformen, die das Herz betreffen, sind v. a. die Leichtketten(AL)- und die ATTR-Amyloidosen, bei der es zur Ablagerung von fehlgefaltetem Transthyretin kommt (entweder als Wildtyp [wtATTR]-Form oder mutiert [mATTR]). Neben speziellen kardialen Biomarkern stehen heutzutage moderne nichtinvasive Bildgebungsverfahren wie das Herz-MRT oder szintigraphische Verfahren zur Verfugung, die die konventionelle Echokardiographie erganzen und neben der Diagnose einer kardialen Amyloidose auch noch eine exakte Erfassung des Auspragungsgrades ermoglichen. Als invasives diagnostisches Verfahren spielt die Endomyokardbiopsie weiterhin eine zentrale Rolle fur die histopathologische Verifizierung bzw. Subtypisierung der kardialen Amyloidose. Wesentliches Ziel des in diesem Positionspapier skizzierten Diagnosepfades ist es, das Vorliegen einer kardialen Amyloidose moglichst sicher und fruhzeitig zu erfassen, das Ausmas der kardialen Amyloidose genau zu charakterisieren, die zugrunde liegende Amyloidoseform sicher zu identifizieren und anschliesend eine gezielte Behandlung zu ermoglichen.

Pathophysiological background and prognostic implication of systolic aortic root motion in non-ischemic dilated cardiomyopathy

Abstract: Recordings of aortic root movement represent one of the first accomplishments of ultrasound in medicine and mark the beginning of functional cardiac imaging. However, the underlying mechanism is not completely understood. Since the aortic root is directly connected to the cardiac skeleton we hypothesize, that the amplitude of systolic aortic root motion (SARM) may be mainly caused by displacement of the cardiac base towards the apex and might therefore be used as measure of left ventricular longitudinal function (LV-LF). One hundred and eighty patients with dilated cardiomyopathy and 180 healthy controls were prospectively included into this study. SARM was lower in patients compared to controls (9 ± 3 mm vs. 12 ± 2 mm, p < 0.001) and lowest in patients with cardiovascular events (9 ± 3 mm vs. 7 ± 3 mm, p < 0.001). During a median follow-up time of 38 months, the combined end-point of cardiovascular death or hospitalization for heart failure was reached by 25 patients (13.9%). Reduced SARM had significant prognostic impact on outcome (hazard ratio 0.74, 95% confidence interval 0.63–0.88, p < 0.001) and remained an independent predictor in the multivariate analysis. Compared to parameters with potential influence on its mechanism, SARM correlated best (r = 0.75, p < 0.001) with global longitudinal strain (GLS). SARM may therefore represent an alternative echocardiographic parameter for the assessment of LV-LF, particularly when GLS is not feasible or apical views are not available.

P991Predicting arrhythmic risk in dilated cardiomyopathy: a systematic review & meta-analysis of clinical parameters

Abstract: Patients with non-ischemic dilated cardiomyopathy (NIDCM) are at increased risk of ventricular arrhythmias and sudden cardiac death (SCD). However, identifying patients at high risk for life-threatening ventricular arrhythmia (LTVA) who may benefit from an implantable cardioverter defibrillator (ICD) remains challenging. We searched MEDLINE and EMBASE for prognostic studies describing predictors of LTVA (defined as sustained ventricular tachycardia (VT), haemodynamically unstable VT, ventricular fibrillation, (aborted) SCD or appropriate ICD intervention) in patients with NIDCM. We excluded articles with composite heart failure and arrhythmic endpoints but lacking (subgroup) analysis for LTVA. Study quality and risk of bias was assessed using the QUIPS-tool, and articles with high risk of bias in ≥2 areas were excluded from analysis. Univariable hazard ratios of reported predictors were pooled from the remaining studies in a meta-analysis using a random-effects model and presented with 95% confidence interval (CI). Out of 1996 unique citations, 51 studies were included comprising 9798 patients with 1493 arrhythmic events. 28 studies were pooled for meta-analysis (mean age 55±4.1 years, 72% male) with a mean follow-up of 3.7±1.9 years. Crude event rate was 4.3% (95% CI 4.02–4.57) per year. From our meta-analysis, hypertension (HR 1.95; CI [1.26–3.00]), history of out of hospital cardiac arrest or sustained VT (HR 4.15; CI [1.32–13.02]), T-wave alternans (HR 6.50; CI [2.46–17.14]), LVEDV per 10ml/m2 increase (HR 1.10; CI [1.10–1.10]), LVESV per 10ml/m2 increase (HR 1.10; CI [1.00–1.22]) and delayed gadolinium enhancement (HR 5.55; CI [4.02–7.67]) were significantly associated with LTVA (figure). The quality of evidence was moderate and there was significant heterogeneity (median i2 57%; IQR 76%) among studies. Additionally from data that could not be pooled, decreased LVEF, history of nsVT and decreased heart rate variability were significantly associated with LTVA. Summary of meta-analysis results The risk of LTVA in NIDCM is 4.3% per year and is considerably higher in patients with hypertension, history of LTVA, decreased LVEF, high LVEDV, high LVESV, T-wave alternans, history of nsVT, decreased heart rate variability and delayed gadolinium enhancement. These results may help determine appropriate candidates for ICD implantation. The high heterogeneity in reported results indicate the need for future multicentre studies to further improve risk stratification in NIDCM. ERA-CVD JTC2016: DETECTIN-HF, 680969 & Dutch Heart Foundation (2016T096)

P3688Familial recurrent autoimmune myocarditis associated with a truncating nonsense mutation of the desmoplakin gene

Abstract: Arrhythmogenic cardiomyopathy (AC) is an important cause of ventricular arrhythmias in children and young adults. AC is associated with mutation of desmosomal proteins, however, cardiac disease penetrance is incomplete and the clinical course varies widely without recognizable exogenous or epi/genetic co-factors. Importantly, DSP mutation carriers may also display entirely non-cardiac e.g. dermatological phenotypes. In two brothers with recurrent fulminant myocarditis, mutation screening of 218 cardiomyopathy-related genes identified a truncating mutation Arg1458* of desmoplakin (DSP). DSP immunhistology unexpectedly revealed complete loss (“knockout”) of DSP protein in endomyocardial biopsies (EMBs), but none of the histological anomalies of AC. Criteria for histological diagnosis of myocarditis were not either fulfilled, and cardiac MRI revealed no features associated with AC. Screening for infections was negative, there was no substance abuse, medication or vaccination. Possible disease triggers were competitive sport events. Myosin and troponin I autoantibodies were detected at titers up to 1:320. We used allele-specific RT-PCR to distinguish if the patients' allele classified as “normal” was actually defective due to promotor mutation or epigenetic silencing. RT-PCRs were done on EMBs and peripheral blood mononuclear cells (PBMCs). In a cohort of dilated cardiomyopathy (DCM) patients we were able to detect DSP transcripts in both, PBMC and left-ventricular heart tissue. RNA sequencing of human PBMC subpopulations suggested that DSP transcription may be restricted to certain immune cell subtypes. RT-PCRs revealed that both Arg1458* carriers have a functional second DSP allele, indicating that their “DSP knockout” occurs at the protein level and may be due to protein instability and degradation within desmosomes. We screened additional existing cohorts for such variants and identified stopgain variant Gln307Ter in a 37-yrs-old woman with ARVC. This patient's sister died from heart failure at the age of 39. In a 59-yrs-old female LVNC patient, stopgain variant Y1391X was identified. Here, family history was unclear, her brother probably died from coronary artery disease. In a 71-yrs-old female DCM patient with no family history, stopgain variant Tyr1512Ter was identified. The described patients with DSP truncations strongly suggest the existence of additional genetic or exogenous modifiers driving pathogenesis either way. DSP defects may cause recurrent myocarditis, and mutation screening is advisable to enable early detection of high-risk patients with similar phenotypes. Our finding of complete myocardial DSP protein loss emphasizes that DNA sequencing may miss critical molecular disturbances. It is indispensable to also analyze transcriptome and protein level in the tissue actually affected in a patient in order to recognize his/her individual pathogenesis.