Abstract 4147419: EKG Abnormalities and Homozygous Embryonic Lethality in Gene-Targeted Mice Mimicking K1479 Acetylation of the Cardiac Na+ Channel Nav1.5

Circulation, Volume 150, Issue Suppl_1, Page A4147419-A4147419, November 12, 2024. Introduction:Nav1.5, the predominant Na+channel in cardiac myocytes, is encoded bySCN5Aand is essential for depolarization and impulse propagation in the heart. Loss of function mutations of Nav1.5 can lead to tachyarrhythmias, conduction disease and dilated cardiomyopathy by altering channel expression, kinetic properties, and/or membrane trafficking. We previously reported that amino acid K1479 of Nav1.5 is acetylated, that K1479 acetylation or mutation to the acetylation mimic glutamine (K1479Q) decreases inward Na+current (INa) in heterologous expression systems by decreasing membrane trafficking, that cardiac myocytes from mice lacking the deacetylase Sirt1 (Sirt1-/-) are hyperacetylated and have less INa, and that Sirt1-/-mice have conduction disease and arrhythmias. Here, we studied the effect of the K1479Q mutation that mimics acetylationin-vivo.Methods:K1479Q knock-in mice were engineered via CRISPR/Cas9 on a C57BL6 background and backcrossed 4 times with C57BL6 wild type (WT) mice. Nav1.5WT/Qheterozygous (het) mice were mated, and male (M) and female (F) gene-targeted offspring and littermate controls were studied by electrocardiograms (EKGs) and echocardiograms (Echos) at 3 and 6 months of age. Data is shown as mean±SEM.Results:The K1479Q mutation was homozygous (hom) embryonic lethal (Nav1.5WT/Qx Nav1.5WT/Qcrosses: WT, n=23; Het, n=49; Hom, n=0). On EKG (WT: n = 5M, 3F; Het: n = 6M, 5F), Nav1.5WT/Qmice had a prolonged PR interval at 3 months (42±1 vs. 36±1 ms, p=0.0003) and at 6 months (46±1 vs. 39±1 ms, p=

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Novembre 2024

Abstract 4137902: Layer-specific Gene Expression Associated with Intima Hyperplasia in Arterio-venous Fistula

Circulation, Volume 150, Issue Suppl_1, Page A4137902-A4137902, November 12, 2024. Background:The mechanism of hemodialysis arteriovenous fistula (AVF) vein intima hyperplasia (IH) may be specific to its layers (intima, media, and adventitia) but is poorly understood. To address this gap, we studied layer-specific transcriptomics related to IH in veins of two-stage AVF creation.Methods:Vein samples were collected during the initial creation of brachial artery-basilic vein AVF (1st stage) and vein transposition surgery 6 weeks later (2nd stage) and were sectioned in OCT. Tissues from each layer were separately collected by laser microdissection. Following Takara’s SMARTer Stranded Total RNA-Seq Pico Input protocol, libraries were constructed and sequenced in NovaSeq. The sequencing reads were processed by fastp, aligned to genome GENCODE 45 by STAR and gene-level counts were estimated by RSEM. Intima was assessed by histology. Layer-specific differentially expressed genes in pre-access or AVF veins associated with IH in AVF veins were detected by edgeR and further identified the enriched pathways and predicted functions using Qiagen IPA.Results:44 veins were collected from 22 patients. 13,522 protein-coding genes that had a raw count of at least 10 in more than 70% of samples were included in analysis. 10 AVF veins had severe IH. Among the layers of pre-access vein, intima had the largest number of genes significantly associated with severe AVF IH and most or all these genes were upregulated (35/4, 26/2, 5/0 for the number of up/downregulated genes in intima, media, and adventitia of pre-access vein, respectively); cellular movement and immune cell trafficking were more strongly activated in intima of pre-access vein with severe AVF IH. No genes in any layer of AVF vein were significantly associated with severe AVF IH. From 1stto 2ndstage, more genes significantly changed expression in intima with severe AVF IH than intima without severe AVF IH (197/150 vs 144/93 for up/downregulated genes), while media (20/4 vs 149/31) and adventitia (99/27 vs 196/70) were the opposite; TGFB1, angiotensinogen, and TNF were more strongly activated in intima, while cell survival and migration were diminished in media and adventitia with severe AVF IH, respectively.Conclusion:Intima of pre-access vein has more genes associated with severe AVF IH. The layer-specific gene expression changes during AVF development and predicted functions are associated with AVF IH. These data can be used to develop layer-specific therapies to reduce AVF IH.

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Novembre 2024

Abstract 4134619: A Novel Missense Mutation in TNNT2 Gene in a Lebanese Pedigree With Ebstein Anomaly And Wolf-Parkinson-White Syndrome: A Case Report

Circulation, Volume 150, Issue Suppl_1, Page A4134619-A4134619, November 12, 2024. Background:Ebstein anomaly (EA) is a rare congenital heart defect occurring in 1.2 to 5 in 100,000 live births, characterized by a downward displacement of the tricuspid valve, thin-walled right ventricle, and tricuspid valve regurgitation. It can present variably from asymptomatic cases to severe symptoms like arrhythmias and right-sided heart failure. EA is often associated with other anomalies such as interatrial communication and mitral valve prolapse. The condition can lead to accessory atrioventricular pathways, frequently resulting in Wolff-Parkinson-White syndrome (WPW), which involves abnormal heart electrical activity and increases the risk of sudden cardiac death. While the genetic basis of EA is not fully understood, it appears to involve multiple genes like FLNA and NKX2-5, MYH6, MYH7 suggesting a complex polygenic inheritance pattern. TNNT2 is known to be associated with Cardiomyopathy but has not been previously associated with EA and WPW.Case:In this report, we present findings from a lebanese family with EA, comprising 2 affected individuals. Whole exome sequencing in the affected individuals identified a pathogenic variant in the TNNT2 gene at coding strain position 260 (a missense mutation: C to T), resulting in the substitution of Proline with Leucine at position 87 in affected individuals (Figure 1). No variants were detected in any other candidate gene examined. Individuals I:1 and II:2 were found to be normal, with no EA findings on echocardiography.Methods:Whole exome sequencing in the patients involved collecting blood samples after obtaining consent. These samples were sent to Centogene lab, where genomic DNA is enzymatically fragmented. The regions of interest are then enriched using DNA capture probes, facilitating detailed genetic analysis.Results:The whole exome sequencing identified a heterozygous missense mutation in both the father and his daughter. This nonsynonymous variant is located on chromosome 1 (GRCh37) in the TNNT2 gene region. The specific variant, NM_001276345.1:c.260C >T p.(Pro87Leu), was found in both individuals.Conclusion:In conclusion, the genetic basis of EA is rather complex and remains poorly understood. It is established that mutations in the TNNT2 gene are linked to several cardiomyopathies, none of them overlap with the described phenotype of our patients. In this report, we therefore confirm the potential role of TNNT2 gene mutation in the genetic basis of familial EA with WPW.

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Novembre 2024

Abstract 4143758: Identifying High-Risk Patients with Pathogenic Variants in LMNA Gene: Genome-First Approach

Circulation, Volume 150, Issue Suppl_1, Page A4143758-A4143758, November 12, 2024. Background:Pathogenic variants in theLMNAgene are associated with highly penetrant cardiomyopathy (CM), with most patients expressing the phenotype by the fourth decade. Those withLMNAvariants are at increased risk of conduction defects or arrhythmia regardless of ejection fraction. Increased availability of genome sequencing enables discovery ofLMNAvariants in apparently asymptomatic individuals, yet data are lacking regarding the phenotypic expression profile to guide clinical management in this genome-first scenario.Aims:Characterize the clinical spectrum ofLMNAphenotypes following genome screening-based identification to inform management and risk stratification.Methods:We screened 175,500 patient-participants with exome sequencing data in the Geisinger MyCode cohort, a healthcare-based population biobank in Pennsylvania, and identified 24 participants with pathogenicLMNAvariants. These results have been disclosed to eligible participants through the MyCode Genomic Screening and Counseling program and referrals to genetic counseling and cardiology were recommended. From manual chart review, we abstracted: age, sex, variant consequence, lifetime cardiovascular symptoms, prior TTE, EKG and Holter data, interventions (e.g. permanent pacemaker (PPM) or implantable cardioverter-defibrillator (ICD) placement), and family history. Malignant arrythmia risk was calculated using an online risk assessment tool.Results:Of the 24, 92% (n=22) were unaware of their variant. The median age at result disclosure was 57 years (IQR: 35-66) with 10/24 (42%) > 60 years. The most common symptoms were presyncope (58%) and palpitations (50%). Of the 24 patients, 21 had EKG or Holter data. AV Block of any degree was seen in 12/21 (57%), and 9 of the 12 (75%) received a PPM or ICD. Of the 19 patients with a TTE, 7 (37%) had an LVEF < 50%. Complete data forLMNArisk assessment was available for 17 patients, and 9 (53%) metACC/AHA/HRScriteria for primary prevention of sudden cardiac death. Evaluation by a genetic counselor was completed in 15/24 (63%). Among the 21 patients with complete data, 10 (48%) showed a family of history of PPM/ICD, and 10 (48%) had a history of heart failure.Conclusions:Individuals with aLMNAvariant identified through genome screening had high rates of cardiac dysfunction and arrhythmia consistent with clinically ascertained cohorts. These results emphasize the value of genomic screening for the identification ofLMNA-associated CM.

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Novembre 2024

Abstract 4144882: Loss of function polymorphism in the ecto-5’-nucleotidase (NT5E) gene increases atherosclerotic burden.

Circulation, Volume 150, Issue Suppl_1, Page A4144882-A4144882, November 12, 2024. Objective:To elucidate the molecular mechanisms by which CD73 variants contribute to inflammation and atherosclerosis in humans.Approach and Results:To explore this knowledge gap, we conducted phenotype-wide association analysis (PheWAS) in a cohort of 25,000 patients to identify ASCVD-associated variants in theNT5E(CD73) gene in a non-biased manner. PheWAS analysis of coding variants identified that the rs200648774 single nucleotide polymorphisms in ecto-5’-nucleotidase (NT5E; CD73) that was associated with atherosclerosis (ICD-9; 440.x codes) in this cohort. The SNP rs200648774 (C– >T; MAF 0.000188) results in an Arginine (R) to Cysteine (C) substitution at amino acid 354 within the active site of CD73 (OR: 10.18, SE: 1.1; P=0.035). This Arginine residue is evolutionarily conserved across species. The variant protein is expressed but displays a loss of function (LOF; CD73 Cys354 variant). To examinethe impact of the CD73 Cys354 variant, we generated a murine model usingEfficientadditions withssDNAinserts-CRISPR (Easi-CRISPR) gene editing. CD73-Arg354/Arg354 (cd73wt/wt) and CD73-Cys354/Cys354 (cd73Δ/Δ) mice in anLdlr-/-background were placed on HFD for 12 weeks then sacrificed for quantification of aortic root atherosclerosis. Representative images of oil red O staining of aortic valve from CD73-Arg354/Arg354-Ldlr-/-(cd73wt/wt,Ldlr-/-) mice (Fig. A; Bar= 100 um) and CD73-Cys354/Cys354Ldlr-/-(cd73Δ/Δ,Ldlr-/-) mice (Fig. B; Bar= 100 um). Quantified area of atherosclerosis in CD73-Cys354/Cys354 (cd73Δ/Δ) aortic roots were significantly higher in CD73-Cys354/Cys354 (cd73Δ/Δ) than in CD73-Arg354/Arg354 (cd73wt/wt) (Fig. C; p=0.0096). The Percentage of Oil Red O staining in aortic root atherosclerotic lesions was also significantly higher in CD73-Cys354/Cys354 (cd73Δ/Δ) aortic roots compared to CD73-Arg354/Arg354 (cd73wt/wt) aortic roots. Together these data demonstrate that the rs200648774 single nucleotide polymorphisms resulting in cysteine substitution for arginine in the active site of CD73 results in a loss of CD73 function that also associates withincreased atherosclerosis in genetically susceptible mice.Conclusion:The LOF rs200648774 single nucleotide polymorphisms associates with atherosclerosis in humans and generation of the CD73-Cys354/Cys354 polymorphism inLdlr-/-mice results in increased HFD induced atherosclerosis

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Novembre 2024

Abstract 4143876: Endothelial Cell Gene Expression Profiling Demonstrates Inflammatory Activation In Young Adults Who Use Electronic Cigarettes Alone And In Combination With Combustible Cigarettes

Circulation, Volume 150, Issue Suppl_1, Page A4143876-A4143876, November 12, 2024. Background:Traditional combustible cigarette (combustible) use induces endothelial dysfunction accelerating cardiovascular disease progression. Young adults frequently use electronic cigarettes (e-cig) that is linked to impaired endothelial cell (EC) function. We aimed to use EC gene expression analysis to explore altered pathways across patterns of tobacco product use.Methods:Healthy adults aged 18-45 who regularly use e-cig (sole or dual), combustible, and non-use controls were with forearm vein EC biopsy and magnetic bead purification. EC total RNA was isolated and profiled on a NextSeq sequencer. Samples with transcript integrity number (TIN) < 10 were removed, genes were filtered with edgeR::filterByExpr, and analyzed with DESeq2. Differentially expressed genes (DEGs) comparing each use group to the non-use group were defined as log2fold change >1 and FDR p1 and p

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Novembre 2024

Abstract 4143866: The Effect of S100A6 Gene Therapy on Cardiac Function in a Rat Model of Ischemic Cardiomyopathy

Circulation, Volume 150, Issue Suppl_1, Page A4143866-A4143866, November 12, 2024. Background:S100A6 is a small calcium-binding protein that is important in managing calcium storage and myocyte contractility. This protein has a low basal cardiac expression and is upregulated following Myocardial Infarction (MI). Previous experiments have demonstrated that S100A6 gene transfer improves left ventricular function after acute ischemia/reperfusion injury.Hypothesis: Delivery of S100A6 by Ultrasound-Targeted Microbubble Destruction (UTMD) after established MI model results in improved left ventricular function and prevention of adverse ventricular remodeling.Aim:Assess the impact of UTMD delivery of S100A6 on cardiac function following experimental MI.Methods:MI was induced through permanent left anterior descending (LAD) coronary artery ligation in 8-week-Spragues Dawley (SD) male rats on day 0. On day 28, by using UTMD methods, we delivered microbubbles (1×109) coupled with either 200 μg of human S100A6 mini-circle DNA or empty minicircles to the left ventricle (LV), while control animals received no therapy. The three groups were monitored weekly for four weeks post-gene delivery using serial echocardiography to follow LV function, followed by tissue collection from various regions of the myocardium.Results:At day 28 post-MI, all groups showed reduced LV ejection fraction (LVEF) and fractional shortening (FS), with LVEF and FS values of 39.47±1.49% and 19.75±2.38%, respectively. Meanwhile, healthy animals showed LVEF and FS values of (63.75±2.38% and 36.20±1.29% (p

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Novembre 2024

Abstract 4135301: Cardiac specific gene therapy to treat diabetic heart failure with preserved ejection fraction

Circulation, Volume 150, Issue Suppl_1, Page A4135301-A4135301, November 12, 2024. Background:We have previously demonstrated that diabetes mellitus (DM) causes cardiac inflammation leading to heart failure with preserved ejection fraction (HFpEF). Arachidonate 5-lipoxygenase (5-LOX), encoded by the ALOX5 gene, is an enzyme that is highly expressed in leukocytes. 5-LOX synthesizes specialized pro-resolving mediators (SPMs) including Resolvin D1 (RvD1), which reduce inflammation.Hypothesis:We hypothesize that cardiac-specific ALOX5 upregulation could prevent diabetes-associated HFpEF without inducing systemic immunosuppression.Methods:DM was induced by feeding mice with a high fat diet (HFD, 60% fat by kcal) starting from 6 weeks of age for 22-24 weeks. At 24 weeks of age, DM mice were treated with RvD1, by intraperitoneal injection at 100 ng/mouse for 2 weeks. To specifically upregulate 5-LOX in the heart, another cohort of DM mice were injected with either AAV9-plain or AAV9-ALOX5viral vectors under the control of the α-myosin heavy chain (MHC) at 22 weeks old. At 28 weeks, we performed echocardiographic measurement of diastolic function and heart extraction.Results:HFD-induced DM mice showed lower cardiac 5-LOX expression (0.72 ± 0.05 a.u. vs. 1.09 ± 0.12, p < 0.05) and RvD1 levels (1 ± 0.08 vs. 1.9 ± 0.14 fold change over DM mice, p

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Novembre 2024

Abstract 4147327: Race and Ethnic Differences in Donor-Derived Cell-Free DNA and Gene Expression Profiling in Heart Transplant Recipients in a Negative Biopsy Cohort

Circulation, Volume 150, Issue Suppl_1, Page A4147327-A4147327, November 12, 2024. Introduction:The Donor-Derived Cell-Free DNA-Outcomes AlloMap Registry (D-OAR) study has highlighted the significant capability of dd-cfDNA, showcasing a 97% negative predictive value (NPV) for identifying both acute cellular rejection (ACR) and antibody-mediated rejection (AMR) at a dd-cfDNA threshold of 0.20%. This development has greatly enhanced the range of biomarkers available to clinicians, confirming dd-cfDNA as a reliable clinical biomarker for monitoring heart transplant (HT) recipients. Short and long-term outcomes for African American HT recipients are worse. Given these findings, our study aims to investigate baseline differences in the levels and positivity rates of dd-cfDNA stratified by race in a negative biopsy cohort.Methods:We conducted a single-center retrospective review of all HT recipients from 2019 to 2023 with at least one valid combined dd-cfDNA sample drawn between April 2019 and July 2023. Multiorgan transplant recipients and those without a paired biopsy result were excluded. A positive biopsy result was defined as >= ISHLT grade 1R/1B or pAMR >0. Dd-cfDNA (AlloSure, AS) result was considered positive if ≥0.12%, and as a sub-analysis using a threshold ≥0.20%. A positive peripheral GEP (pGEP, AlloMap, AM) test was defined as >30 in the first five months post-transplant and >34 afterward. Samples associated with a positive biopsy result were excluded. We further stratified our cohort based on race.Results:Of 643 paired dd-cfDNA/GEP samples from 227 patients, the median age was 55 years, and 27% were female. The cohort was stratified into four categories: 53% were white, 18.8% were AA, 20.4% were Hispanic/Latino, and 7.8% were of other races. We observed no baseline differences in the positive dd-cfDNA levels (p=0.39) and positivity rates of dd-cfDNA at a threshold of 0.12% and 0.20% (p=0.08, p=0.06) or GEP positivity rates (p=0.52) between the 4 race categories in our surveillance cohort (Figure 1). Further comparison of patients treated for rejection based on non-invasive monitoring did not reveal a difference.Conclusions:In our surveillance cohort, dd-cfDNA levels and positivity rates were not different between AA and white HT recipients. Further prospective randomized trials are needed to elucidate potential race-related differences in dd-cfDNA levels.

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Novembre 2024

Abstract 4141227: Characterization of NIMA-related kinase 7 (NEK7)-NLRP3 inflammasome complex in macrophages by combining CRISPR/Cas9 gene-editing with comprehensive proteomic

Circulation, Volume 150, Issue Suppl_1, Page A4141227-A4141227, November 12, 2024. Background:The aberrant activation of the NLRP3 inflammasome in macrophages promotes chronic inflammation in cardiovascular disease (CVD). NEK7 is essential to the NLRP3 inflammasome’s function, however, its role in inflammasome-mediated macrophage activation has yet to be elucidated.Methods&Results:We employed CRISPR/Cas9 gene editing to delete NEK7 in human primary macrophage cells (PBMCs) and in a macrophage-like cell line (THP-1). First, we employed mass spectrometry-based proteomics to monitor the response of Scramble control (ΔScr) or NEK7-null (ΔNEK7)-THP-1 cells to monosodium urate crystal (MSU). We quantified 4,030 proteins representing ΔNEK7-THP-1 and ΔScr-THP-1 conditions, analyzed at 4 timepoints (0hr, 1hr, 3hr, 6hr; MSU treamtent). NEK7 was identified in ΔScr but not in ΔNEK7 cells. In order to identify proteins whose abundances were suppressed by ΔNEK7, we performed a multiplexed high-dimensional clustering and network analysis using our custom made software (XINA, Fig.A). Specifically, we identified NOD-like receptor and Interleukin-1 (IL-1) signaling in clusters 16 and 17, that a) increased steadily over the timepoints and b) were overrepresented by proteins from the ΔScr condition (Fig.A, red rectangles). Whereas in ΔNEK7, these proteins migrated to either clusters 3, 5, 25, or 35 (Fig.B, alluvial plot), indicating their suppression (Fig.A, blue rectangles). In ΔNEK7-PBMCs, IL-1β secretion decreased in response to MSU compared to ΔScr-PBMCs (Fig.C, n=8); and less chemotaxis as determined by high-content imaging that monitored PBMC migration (Fig.D, n=6). Finally, we confirmed that small molecule inhibitor of the NLRP3-NEK7 complex itself decreased IL-1β secretion in an MSU-elicited peritonitis mouse model (C57BL/6J, n= 8, Control: PBS, p

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Novembre 2024