tbuckley/cabot-search huggingface dataset:
Bradycardia in a long QT type 2 family: coinciding KCNH2 and HCN4 variants
Authors: J S Copier, K Andrzejczyk, A S Amin, S N Van Der Crabben, L Beekman, C R Bezzina, A O Verkerk, E M Lodder
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): the Dutch Research Council: NWO Talent Scheme Background A large multigenerational family harboring a pathogenic KCNH2 variant (L69P) was identified. This gene encodes the hERG channel, responsible for the cardiac rapid delayed rectifier K+ current (IKr). Pathogenic variants in KCNH2 can cause Long QT syndrome type 2 (LQTS2). Interestingly, in addition to LQTS2 we observed a high incidence of bradycardia in this family. Bradycardia is a known feature of some types of LQTS. However, evidence of bradycardia in LQTS2 is limited to a few sporadic cases. Purpose This study aims to identify the genetic variants and biophysiological changes in ion channel function, explanatory of the phenotypes LQTS2 and bradycardia. Methods An overview of the phenotype and genetic information of the index and family members was generated , including symptoms and electrocardiogram (ECG) parameters. QTc was calculated using Bazetts’ correction. Segregation of the identified genetic variants with LQTS and bradycardia were determined by LOD score. Biophysiological properties of the encoded ion channels was measured by manual whole-cell patch-clamp experiments. Results On the basis of linkage analysis, the pathogenic variant KCNH2-p.L69P was found to be unrelated to the bradycardia. Therefore, Sanger sequencing of HCN4, encoding the channel responsible for the hyperpolarization-activated current (If), an important current for sinoatrial node automaticity, was performed. We identified the HCN4-p.R666W variant in multiple family members, which co-segregated with bradycardia (LOD-score 3.2). Patients carrying both variants had more severe phenotypes than carriers of a single variant. Patch-clamp experiments in HEK293A-cells expressing wild type, or KCNH2-p.L69P show a reduced current density, and an altered time component of the fast deactivation, explaining the observed LQTS2. Functional assays of HCN4-p.R666W will elucidate the biophysiological changes possibly underlying the bradycardia. Conclusion we present a large multigenerational family that harbors a likely pathogenic variant in HCN4 in conjunction with a pathogenic variant of KCNH2. Double carriers were more affected than single carriers, arguing for continued alertness and deep phenotyping even in families with known pathogenic variants. Furthermore, we identified functional changes in the kinetics of the hERG channel encoded by KCNH2-p.L69P, elucidating the molecular mechanism underlying LQTS2 in this family.
Real-time (re)shaping of cardiac action potentials by an opto-electronic feedback control system in the multicellular setting
Authors: B Ordog, T De Coster, C I Bart, J Zhang, G J J Boink, W Bax, S Deng, B L Den Ouden, A A F De Vries, D A Pijnappels
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Research Council Starting Grant and Consolidator Grant to Daniël A Pijnappels Background The membrane potential (Vm) in cardiomyocytes fulfills essential regulatory roles in various biological functions, including not only action potential (AP) propagation and mechanical contraction, but also homeostatic regulation. In-depth studies into these roles have been severely hampered by the lack of research methods allowing full control over Vm, especially in multicellular cardiac preparations. Purpose We aimed to unlock new research possibilities by the development of an experimental system (APqr) capable of full Vm control, including instantaneous modulation of AP morphology on a multicellular levelin the multicellular setting. Methods Monolayers of immortalized human atrial myocytes (hiAMs, n=7) were genetically modified to express the blue light-activatable cation channel Cheriff and the red light-sensitive inward chloride pump Jaws for depolarizing and re- or hyperpolarizing effects, respectively. Real-time Vm readout was obtained by patch clamp electrophysiology. Deviations of Vm from reference values were calculated by a custom closed-coop controller. A 470-nm and a 617-nm LED were modulated by the controller in a Vm deviation-dependent manner, selectively activating Cheriff or Jaws. Electrical disturbances were introduced by application of 4-aminopyridien (4AP, 200 µM) or a preprogrammed blue-light pulse creating abnormal cation influx during the repolarization phase of the hiAM AP. Results Average AP durations at 90% repolarization (APD90) increased by 82.4 ms following 4AP application and by 362.5 ms in the presence of light-induced abnormal cation influx compared to control conditions. APqr reduced these APD90 differences to 1.9 ms and 4.6 ms on average, with Vm deviations less than 2.5 mV in 74.7% and 94.4% of the time, respectively. APqr could also be applied for the enforcement of arbitrary AP shapes. In these experiments, reference Vm values consisted of APs recorded from hiAM monolayers exposed to drugs with APD-prolonging (4AP) or shortening (carbachol) effects. APqr was able to enforce these reference APs on hiAM monolayers with high accuracy, with Vm deviations less than 2.5 mV in 95.8% and 94.4% of the time, respectively. Conclusions APqr preserves AP morphologies in the presence of electrical perturbations of different origin without any prior knowledge of the disturbance and enforces arbitrary AP morphologies with high accuracy in an immediate and self-regulatory manner. Collectively, these results set the stage for the refinement and application of opto-electronic control systems to enable in-depth investigation into the regulatory roles of the membrane potential in health and disease.
Increased perivascular fibrosis and pro-fibrotic cellular transition in intramyocardial blood vessels in patients with myocardial infarction
Authors: Z Jiang, G Sorrentino, S Simsek, H W M Niessen, P A J Krijnen
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): China Scholarship Council Background Myocardial infarction (MI) is pathologically characterized by irreversible myocardial necrosis caused by ischemia. Intramyocardial vascular dysfunction is believed to increase the risk of MI. In this study, we investigated intramyocardial blood vessels in deceased patients during the early and chronic phases of MI to explore the involvement of perivascular fibrosis and pro-fibrotic cellular transitions in the pathological process of MI. Methods Left ventricular tissue (LV) was obtained from the infarction area of autopsied patients with early-phase MI (3-6 hours old; n=23), chronic-phase MI (5-14 days old; n=12), and from non-infarcted controls (n=14). We quantified perivascular fibrosis using EVG staining and fibroblast activation protein (FAP) expression using immunohistochemistry. Co-localization of smooth muscle actin (SMA) or CD31 with fibroblast marker S100A4 indicative of transition of smooth muscle cells (SMC) and endothelial cells (EC) toward fibroblast-like cells in intramyocardial vessels was quantified using immunofluorescent microscopy. Results Compared to controls (61.03%), perivascular fibrosis was significantly elevated in MI patients (early-phase 77.20%; chronic-phase 82.58%)(p&amp;lt;0.0001), with the highest level observed in the infarct cores of chronic-phase patients (95.18%). Compared to controls, FAP expression was 3.5-fold higher in early-phase- and 15.3-fold higher in chronic-phase MI patients (p&amp;lt;0.05), wherein FAP expression again was highest in the infarct cores. Furthermore, in both early- and chronic-phase MI, SMC- and EC fibroblast-like cellular transition was increased. The fraction of SMA+S100A4+ vessels was significantly higher in early-phase MI (31.96%) and chronic-phase MI (21.9%: border zone; 37.25%: infarct core) compared to controls (8.95%)(p&amp;lt;0.05). Similarly, the fraction of CD31+S100A4+ area was significantly increased in early-phase MI (10.14%) and chronic-phase MI (8.31%: border zone 10.15%: infarct core) compared to controls (2.67%)(p&amp;lt;0.05). Conclusion We observed increased perivascular fibrosis, fibroblast activation and fibroblast-like cellular transition toward a pro-fibrotic phenotype of vascular cells in intramyocardial blood vessels in MI patients, that may contribute to the development of MI. The further increase of FAP expression and perivascular fibrosis, particularly in the infarct core, in the chronic-phase suggest that MI itself can exacerbate fibroblast activation and perivascular fibrosis, theoretically increasing the risk of reinfarction.FAP expression and perivascular fibrosispro-fibrotic vascular cellular transitio
From genes to phenotype: investigating the link between smad2rs29725537:c&amp;gt;a and high take off in mice
Authors: M T Soto-Navarrete, B Pozo-Vilumbrales, M A Lopez-Unzu, M C Fernandez, A Hernandez-Martin, A C Duran, B Fernandez
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Junta de Andalucía, Ministerio de Ciencia e Innovación, Gobierno de España. Introduction and Purpose High take off (HTO) is a congenital anomaly with a prevalence of 0.36% that can cause severe ischemia and sudden cardiac death. The C57Bl/6 (B6) mouse strain shows around 60% incidence of HTO, whereas it is absent in the Balb/c (BC) strain. The aim of this study was to identify the genes responsible for the development of HTO. Methods Following an inheritance study, a genetic linkage study was performed in B6C mice using 134 microsatellites (MIT). After selection of Smad2 as a candidate gene, a genotype-phenotype study was performed by PCR-RFLP genotyping of 293 B6C mice. The process of coronariogenesis was examined in E13.5 and E14.5 mouse embryos of B6 (n = 27) and BC (n = 23) strains with specific markers for the vascular plexuses involved in coronariogenesis (PROX1 and ERG 1/2/3) and for SMAD2. Finally, the SMAD2 and pSMAD2 protein expression levels were analyzed by western blot in ventricle, liver, and kidney of B6C mice. Results The incidence of HTO in B6, BC and B6C mice were concordant with an inheritance pattern mediated by a dominant causal allele and dominant modifier in the BC strain that reduces the incidence of HTO. The genetic linkage study revealed the association of a region between markers MIT-49 and 106 on chromosome 18 with the presence of HTO. This region contained a total of 10 genes, of which Smad2 was selected as a candidate gene because of its functions in aortic root formation. Comparative sequence analysis of Smad2 between the B6 and BC mouse strains uncovered an intronic SNP (Smad2rs29725537:C&amp;gt;A or Smad2C&amp;gt;A) that predicts and error in the splicing of intron 10-11. A statistically significant association (p&amp;lt;0.05) between the Smad2C&amp;gt;A allele and the presence of HTO was found. pSMAD2 was detected in embryonic coronary primordia, the subepicardial aortic plexus (SAP) and the primary coronary plexus. Around 60% of B6 examined embryos showed an exacerbated SAP compared to the BC embryos. Additionally, we detected a differential expression of total SMAD2, but not of pSMAD2, in different organs according to the Smad2C&amp;gt;A allele genotype (C/C &amp;gt; A/C &amp;gt; A/A). Conclusions We conclude that: 1) Smad2C&amp;gt;A allelic variant is associated with HTO in mice, suggesting it as a major causal factor. 2) Smad2 altered expression may affect the establishment of the embryonic coronary primordia leading to a mispositioned ostium. 3) the Smad2C&amp;gt;A allele has a systemic effect on total SMAD2 expression without affecting its phosphorylation level, which suggest a compensatory mechanism of expression that maintain the normal activity of pSMAD2 in most tissues.
The impact of SLCO1B1 single nucleotide polymorphism and non-genetic factors on statin-induced myopathy
Authors: T H Alaryan, L Youssef
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements None. Background Statins, also known as HMG CoA Reductase Inhibitors, are a class of drugs considered the drug of choice for treating hypercholesterolemia. Statins are well tolerated; however, they may cause severe myopathy in 20% to 30% of patients, due to the individual variation regarding its efficacy and related adverse effects. Of these, comes the Single Nucleotide Polymorphism (SNP) T521C of the SLCO1B1 gene that encodes the protein involved in the trafficking of statins from the blood to hepatocytes which is called Organic Anion Transport Protein 1B1 (OATP1B1). The T521C single nucleotide polymorphism (SNP) results in a substitute of valine with alanine resulting in a decreased or lack of functional protein. Purpose The aim is to determine the frequency of the high-risk C allele and to define its impact on statin-induced myopathy in Syrian patients on statins. In addition to the non-genetic factors that may affect the ability to develop statin-induced myopathy. Methods This was an observational case-control study that had ethical approval from Damascus University (No.433/ 2020). The case group included 44 patients on statins who experienced myopathy, 18 patients who had increased creatinine kinase levels (CK), and 26 patients with normal CK levels, while the control group encompassed 56 patients who were taking statins and had no muscular adverse events. The DNA was extracted from each sample and then genotyped using standard sequencing of specific PCR products using a specific pair of primers. Results The age of patients in the case arm ranged between 27 and 84 years with an average ± SD of (58.2 ± 12.7 years), 70% of them were males. In comparison with (53.34 ± 12.4 years) in the control arm, 66% of them were males without a statistically significant differences (p=0.672, 0.057) respectively. The statin type and dose have a statistically non-significant effect, the average statin dose in the case arm and the control arm was 26.02 mg and 31.27 mg respectively (p=0.072). While the statin type treatment varied as 59% used atorvastatin and 39% used rosuvastatin in the case group compared with 71% used atorvastatin and 27% used rosuvastatin in the control group, without a statistically significant difference (p=0.252). The frequency of the C allele reaches 19.3% and is distributed in three genotypes: wild-type TT (68%), heterozygote TC (25%), and homozygote CC (7%) in the case arm, while it does not exceed 8% in the control arm with the absence of the CC genotype. Only a statistically significant difference was found in the frequency of the CC genotype between these two groups (p=0.047). Conclusion Our study is the first to identify the frequency of the 521T&amp;gt;C SNP of the SLCO1B1 gene in Syrian patients taking statins. Our data reveals a high prevalence of risk allele C in the patients who suffer from statin-induced myopathy with a statically significant difference from the control arm (p=0.026).
Titin mechanical unloading disrupts sarcomere tensional homeostasis triggering fast, non-canonical myocardial fibrosis
Authors: M Lopez-Unzu, M R Pricolo, R Silva-Rojas, N Vicente, M Gavilan-Herrera, D Velazquez-Carreras, C Morales-Lopez, E Herrero-Galan, J Alegre-Cebollada
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): We acknowledge funding from Ministerio de Ciencia e Innovación (Madrid, Spain) through grant FJC2021 047055-I and European Research Council (ERC) through grant H2020-ERC-2020-COG (ProtMechanics-Live). Background/Introduction Stresses exerted during myocardial contraction and relaxation cycles are mainly braced by mechanical proteins located in the extracellular matrix (ECM) and cardiomyocytes (CMs). Titin (TTN) is a gigantic protein that scaffolds the sarcomere (i.e. the basic unit of contraction). Since most of the CM cytoskeleton is occupied by sarcomeres, titin is an essential structural hub for the maintenance of a homeostatic level of mechanical tension. Purpose It has been shown that mechanical disruption of the ECM affects the equilibrium forces between CMs and the ECM, leading to morphological changes in sarcomeres. However, potential alteration of tensional homeostasis resulting from defective mechanics of CM proteins remains unknown due to the lack of tools for in vivo studies. Therefore, the aim of this study is to explore the in vivo response of the myocardium to the abrupt cessation of the mechanical properties of titin. Methods For this purpose, we have experimentally challenged CMs to a tensional unloading by means of a titin cleavage model (TEVs-TTN) [1], both in vitro, using neonatal CM (NMCM), and in vivo. In this model, a cassette with a tobacco etch virus protease (TEVp) recognition sequence has been included in the I-band of titin. Transducing TEVp with adeno-associated virus (myoAAV), we were able to cleave titin in living CMs, ceasing only its mechanical properties. Samples were analyzed using an array of techniques such as histology, immunofluorescence and bulk and single-nucleus RNAseq. Results Our results show that while in NMCM we obtain a complete titin cleavage, in vivo we observe mosaic expression of TEVp and no more than 30% cleavage of the protein. In both cases, TEVp expression in TEVs-TTN does not affect cell viability. However, mild myocardial titin cleavage leads to a fibrotic response in less than six days, characterized by an increase in interstitial collagen and an expansion of cardiac fibroblasts population. Transcriptional and phospo-SMAD2/3 analysis results suggest that this fibrotic response occurs without activation of the canonical TGFβ pathway. Conclusion Taken together, our results suggest that the loss of titin mechanical-structural function in cardiomyocytes derived from the cleavage of a single peptide bond elicits a fast fibrotic compensatory response in the myocardium through intercellular communication with fibroblasts.
Epicardial cell participation in cardiac repair requires epithelial-to-mesenchymal transition
Authors: A M Smits, T J Streef, T Van Herwaarden, C Balbi, A Vegh, E Groeneveld, M J Goumans
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation During development, the epicardium forms as a single cell layer on the outside of the heart. Part of these cells undergo epithelial-to-mesenchymal transition (EMT) and migrate into the myocardium where epicardial-derived cells (EPDCs) participate in the formation of the heart by contributing cells and by producing paracrine factors. In the adult heart the epicardium exists as a dormant layer until there is ischemic injury which leads to a partial reactivation and participation in the repair process. Therefore, the epicardium is considered an interesting cell source for endogenous cardiac repair. Aim to establish if differences between developmental and adult epicardium exist, and in which state (pre- or post-EMT) epicardial cells contribute efficiently to cardiac repair. Methods Primary epicardial cells were isolated from human fetal and adult cardiac tissue samples and cultured as epicardial cells (EPIs) or as EPDCs after inducing EMT with TGFβ3. Cells were subjected to RNA-sequencing or 24hrs of conditioning medium. Myocardial infarction (MI) and intramyocardially injection of EPIs and EPDCs was performed in NOD-SCID mice. Results Fetal and adult EPDCs displayed similar transcriptomic and paracrine profiles. In vitro, the conditioned medium of both cell types equally conveyed cardioprotection to staurosporin-treated cardiomyocytes. Next, we studied the effect of EMT: comparison of adult EPIs with EPDCs revealed that EPDCs have a angiogenic profile. Six weeks post-MI transplantation of adult EPIs or EPDCs resulted in a higher EF (25.4±3.8 vs. 11.1±4.6%, P&amp;lt;0.005), lower ESV (139.6±13.5 vs, 91.37±14.2ul, P&amp;lt;0.05), and a smaller infarct size in EPDC-recipients. EPDC-recipient hearts contained more proliferating cells at 3 days, and a higher vessel density at 6wks post-MI. Interestingly, while cell engraftment was equal in both groups at 3days, no cells were retrieved at 6wks supporting a paracrine effect. Conclusion epicardial EMT is essential to unleash the predominantly paracrine contribution of epicardial cells in cardiac repair.
The diabetic myocardial transcriptome reveals Erbb3 as a novel biomarker of incident heart failure
Authors: M Conning-Rowland, M Giannoudi, M Drozd, O Brown, N Yuldasheva, C Cheng, P Meakin, S Straw, J Gierula, R Ajjan, M Kearney, E Levelt, L Roberts, K Griffin, R Cubbon
Journal: Cardiovascular Research (2024)

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): British Heart Foundation Background/Introduction People with diabetes mellitus (DM) are at high risk of developing heart failure, but the molecular basis of this is not well understood. Elucidating the mechanistic pathways may help to improve patient stratification and develop targeted therapies. Purpose We set out to define differentially expressed genes (DEGs) in diabetic myocardium and validate arising hits in their circulating protein form, with a view to informing biomarker development and improving understanding of diabetic heart disease. Methods Transcriptomic (RNA-seq) data from the Genotype-Tissue Expression (GTEx) project was used to compare gene expression in participants with (n=&amp;gt;100) versus without (n&amp;gt;300) DM (pooled type 1 and 2 diabetes mellitus), in both the right atrial (RA) and left ventricular (LV) myocardium; analyses were adjusted for technical, demographic and disease covariates. Where available, plasma proteomic data from the UK Biobank (UKB) cohort was used to validate DEGs from GTEx in their circulating protein form. Hits with directionally concordant differential expression in GTEx and UKB were further characterised as plasma proteins in UKB, including over 50,000 participants irrespective of DM status; this included analysis of incident heart failure, cardiovascular mortality and left ventricular function on cardiac magnetic resonance imaging. Results Pooled across the RA and LV, there were 64 DEGs associated with DM, with no overlap between the RA and LV hits. UKB plasma protein data was available for 6 of these. Only ERBB3 showed directional concordance with transcriptomic data, being lower in the myocardium and blood of people with DM. People in the lowest quartile of ERBB3 plasma protein had increased adjusted risk of incident heart failure and cardiovascular death than participants in all other quartiles. Lower concentrations of plasma ERBB3 protein were also associated with increased LV mass and impaired LV contractility. Conclusion Lower plasma ERBB3 concentration is more common in people with DM and is associated with LV dysfunction, incident heart failure and cardiovascular mortality. This highlights the potential of ERBB3 as a novel biomarker for individuals at risk of heart failure. Importantly, cancer therapies targeting ERBB3 and related family members can induce heart failure, and recombinant forms of the ERBB3 ligand neuregulin-1 appear to improve LV contractility, further suggesting a role of ERBB3 in the development of diabetic heart disease.