Pereira, Naveen L.

BACKGROUND: Heart failure remains a global health burden, and patients hospitalized are particularly at risk, but genetic associates for subsequent death or rehospitalization are still lacking. METHODS: The genetic substudy of the ASCEND-HF trial (Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure) was used to perform genome-wide association study and transethnic meta-analysis. The overall trial included the patients of self-reported European ancestry (n=2173) and African ancestry (n=507). The end point was death or heart failure rehospitalization within 180 days. Cox models adjusted for 11 a priori predictors of rehospitalization and 5 genetic principal components were used to test the association between single-nucleotide polymorphisms and outcome. Summary statistics from the 2 populations were combined via meta-analysis with the significance threshold considered P <5×10 − 8 . RESULTS: Common variants (rs2342882 and rs35850039 in complete linkage disequilibrium) located in FGD5 were significantly associated with the primary outcome in both ancestry groups (European Americans: hazard ratio [HR], 1.38; P =2.42×10 −6 ; African ancestry: HR, 1.51; P =4.43×10 − 3 ; HR in meta-analysis, 1.41; P =4.25×10 −8 ). FGD5 encodes a regulator of VEGF (vascular endothelial growth factor)-mediated angiogenesis, and in silico investigation revealed several previous genome-wide association study hits in this gene, among which rs748431 was associated with our outcome (HR, 1.20; meta P <0.01). Sensitivity analysis proved FGD5 common variants survival association did not appear to operate via coronary artery disease or nesiritide treatment ( P >0.05); and the signal was still significant when changing the censoring time from 180 to 30 days (HR, 1.39; P =1.59×10 −5 ). CONCLUSIONS: In this multiethnic genome-wide association study of ASCEND-HF, single-nucleotide polymorphisms in FGD5 were associated with increased risk of death or rehospitalization. Additional investigation is required to examine biological mechanisms and whether FGD5 could be a therapeutic target. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT00475852.

Antiplatelet therapy is the mainstay of pharmacologic treatment to prevent thrombotic or ischemic events in patients with coronary artery disease treated with percutaneous coronary intervention and those treated medically for an acute coronary syndrome. The use of antiplatelet therapy comes at the expense of an increased risk of bleeding complications. Defining the optimal intensity of platelet inhibition according to the clinical presentation of atherosclerotic cardiovascular disease and individual patient factors is a clinical challenge. Modulation of antiplatelet therapy is a medical action that is frequently performed to balance the risk of thrombotic or ischemic events and the risk of bleeding. This aim may be achieved by reducing (ie, de-escalation) or increasing (ie, escalation) the intensity of platelet inhibition by changing the type, dose, or number of antiplatelet drugs. Because de-escalation or escalation can be achieved in different ways, with a number of emerging approaches, confusion arises with terminologies that are often used interchangeably. To address this issue, this Academic Research Consortium collaboration provides an overview and definitions of different strategies of antiplatelet therapy modulation for patients with coronary artery disease, including but not limited to those undergoing percutaneous coronary intervention, and consensus statements on standardized definitions.

Introduction: Pathogenic loss-of-function variants in the RBM20 -encoded RNA-binding motif 20 splicing regulator cause a severe form of arrhythmogenic dilated cardiomyopathy (DCM). Erroneous splicing of TTN -encoded titin contributes to the pathogenesis of RBM20 -mediated disease. However, studies exploring the clinical course of RBM20 -mediated arrhythmogenic DCM alone or in comparison to TTN -mediated DCM, the most common familial cause of DCM, are lacking. Methods: The Mayo Clinic Genetic Arrhythmogenic Cardiomyopathy Registry (n=391) was used to identify all patients with a pathogenic/likely pathogenic (P/LP) variant in either RBM20 or TTN . For the purposes of this study, a ventricular arrhythmia (VA) event was defined as sudden cardiac arrest, sustained ventricular arrhythmia, or an appropriate ICD shock and an advanced heart failure (AHF) event was defined as ventricular assist device implantation or heart transplantation. Results: Overall, 40 patients with a P/LP variant in RBM20 (50% female) and 70 patients with a P/LP variant in TTN (43% female) were identified. The prevalence of a cardiac phenotype in patients with RBM20- and TTN -mediated disease was 88% and 83%, respectively. RBM20 patients were more likely to have a family history of sudden cardiac arrest (78% vs 34%; p < 0.0001) and cardiomyopathy (90% vs 61%; p=0.001). No difference in rate of ICD implantation (35% versus 33%) was observed. Interestingly, the prevalence of AHF events (10% vs 6%; p=0.5) and VA events (28% vs 24%; p=0.7) was similar between RBM20 - and TTN -positive patients. However, RBM20 patients were younger than TTN patients at the time of their event (37 ± 18 years vs 50 ± 17; p=0.0004). Time-to-event analysis showed RBM20 patients had an earlier time to AHF event (p=0.05) and time to VA event (p=0.03) than TTN patients. The mean age for AHF events was 25 years for RBM20 patients (N=4) and 47 years for TTN patients (N=4). The mean age for VA events was 29 years for RBM20 patients (N=10) and 42 years for TTN patients (N=14). Conclusions: RBM20 -mediated arrhythmogenic DCM represents a highly penetrant genetic heart disease with potentially life-threatening VAs and end stage heart failure manifestations occurring at a significantly younger age in comparison to TTN -mediated DCM.

Introduction: Genome-wide association studies have identified common genetic variants associated with hypertrophic (HCM) and dilated cardiomyopathy (DCM) and left ventricular (LV) characteristics. However, the association of these variants with myocardial fibrosis (MF), an important pathophysiological mediator of cardiomyopathy, is unknown. Hypothesis: We used the Multi-Ethnic Study of Atherosclerosis (MESA), to evaluate the association of these loci with interstitial MF measured by cardiac MRI (CMR). Methods: Unrelated MESA participants with T1-mapping CMR and no history of MI or heart failure were included (n=1,235). We used the extracellular volume (ECV) fraction as a well-established surrogate of interstitial MF. Genotyping was performed by Affymetrix Human SNP array 6.0, and imputation was performed using the TOPMED reference panel. Log ECV(%) was regressed on 50 candidate SNPs, in each ethnicity/race group, adjusting for age, sex, and population stratification principal component. The race-specific results were pooled by fixed-effect meta-analyses using METASOFT. Results: The SMARCB1 rs2186370 intronic variant, previously identified as a risk variant for DCM and HCM, was associated with ECV (p=0.0004). The rs2186370 A allele (frequency: 0.18 in Whites, and 0.50 in African Americans) was associated with a 1.6% increase in ECV. The rs2070458 A allele (another SMARCB1 intronic variant), in complete linkage disequilibrium with rs2186370, was known previously to be associated with increased LV wall thickness, mass, and concentricity. The direction of effect was similar in all four ancestry groups, but the effect was strongest in African Americans. These variants are strong expression quantitative loci (eQTLs) in human LV tissue and are associated with genotype-dependent expression of SMARCB1 ( p =7.3х10 -22 ) and MMP11 ( p =2.5х10 -24 ). Conclusions: In conclusion, variants in two linked SMARCB1 loci previously associated with HCM, DCM and LV traits, are associated with CMR-based interstitial MF. These loci are eQTL not only for SMARCB1 but also for MMP11 an important mediator of MF . These findings underscore the important link between MF and CM, and potentially provide novel mechanistic targets in understanding the development of CM.

Introduction: It has been previously demonstrated that cardiomyopathy predisposing common genetic variation in SMARCB1 is associated with interstitial myocardial fibrosis (MF) as determined by cardiac MRI (CMR) linking the development of cardiomyopathy with MF. SMARCB1 is known to be a tumor suppressor, but it’s role in the pathophysiology of MF and fibroblast physiology has not been functionally validated. Hypothesis: SMARCB1 plays an important role in regulating human cardiac fibroblast (HCF) differentiation/activation and collagen deposition, which are the critical steps in the development of MF. Methods: Cultured HCFs were treated with TGF-β1 (10ng/ml) for 48hrs to transdifferentiate into myofibroblasts, which are characterized by increased expression of α-smooth muscle actin (α-SMA, ACTA2) and collagen I (COL1A1). HCFs were transfected by siRNA using Lipofectamine™ RNAiMAX Transfection Reagent to knock-down (KD) the expression of SMARCB1 . Total RNA and protein were extracted from cell lysate followed by qPCR and Western blot (WB) to quantify the expression level of SMARCB1, ACTA2 and COL1A1. Triplicate experiments were performed using biologically independent samples. For statistical analysis, a paired two-tail t-test was used. Results: HCFs treatment with TGF-β1, resulted in a significant decrease in expression of SMARCB1 (p=0.031) with accompanying significant increase in expression of ACTA2 (p=0.025) and COL1A1 (p=0.0015) as compared to control by qPCR and WB. SMARCB1 KD resulted in a further significant increase in expression of ACTA2 (p=0.018) and COL1A1 (p=0.028) as compared to non-target siRNA control group at both the transcript and protein level. Conclusion: We demonstrate for the first time that a gene associated with the development of cardiomyopathy SMARCB1 mediates TGF-β1 induced cardiac fibrosis. These findings suggest SMARCB1 as a potential therapeutic target to attenuate MF in cardiomyopathy.

Purpose of review Advances in pharmacogenomics have paved the way for personalized medicine. The purpose of this review is to summarize the background, rationale, and evidence for pharmacogenomics in cardiovascular medicine. Recent findings Randomized clinical trials have supported the role of a genotype-guided approach for antiplatelet therapy in patients with coronary artery disease undergoing percutaneous coronary interventions. Additionally, there is increasing evidence supporting the association of certain genetic variants and risk of statin associated muscle symptoms. Furthermore, germline genetic variation is being used as a biomarker to target patients with specific therapy. Summary Pharmacogenomics has the potential to improve patient care by providing the right drug to the right patient and could guide the identification of novel drug therapies for cardiovascular disease.

Abstract Although immunosuppressive drugs improve short term survival, rejection incidence and long term survival remain largely unchanged in heart transplant patients. While Human Leukocyte Antigen (HLA) is a common initiator of graft-specific immune responses, non-HLA antibody mediated rejection (AMR) also commonly occurs. Furthermore, non-HLA antibodies have been implicated in cell mediated rejection and cardiac allograft vasculopathy. Therefore, there is a need to identify the role of non-HLA antigens in heart transplant rejection. Serum from heart transplant patients lacking donor specific anti-HLA antibodies was collected longitudinally; pre-transplantation, acute rejection, and post-rejection for patients with AMR and matched controls. Serum IgG was used to form anti-human heart affinity columns and antigenic proteins from donor heart extracts captured. Antigens were eluted from the columns and subjected to LC-MS/MS. Longitudinal graft-specific changes in immune response were calculated. Response toward non-HLA antigens increased longitudinally, with 41 high prevalence antigens found in ≥50% of the cohort. Co-culturing cardiomyocyte and endothelial cells with patient IgG indicated cell function changes correlated with specific antigens (e.g., Prohibitin). Immunofluorescence staining of patient biopsies revealed that longitudinal increase in antigen expression correlated with non-HLA antibody response. The non-HLA antigens identified in this study elicit acute and chronic graft-specific adaptive immune responses in heart transplant recipients. Antibodies against these non-HLA antigens induced cellular dysfunction by changing expression of their target protein in the donor heart.

Abstract Background A genome-wide association study (GWAS) assessing change in left ventricular ejection fraction (LVEF) in dilated cardiomyopathy (DCM), a surrogate marker of morbidity and mortality in heart failure (HF), had not been performed previously and could provide insight into novel biological pathways that could lead to the development of new drugs that might target myocardial recovery. The presence and extent of cardiac fibrosis in DCM is independently associated with myocardial recovery and cardiovascular mortality. Purpose To identify the biological relevance of genetic targets that are associated with change in LVEF in patients with DCM. Methods A GWAS was performed using DNA from 686 patients with recent onset DCM who were on standard HF therapy using change in LVEF at a median of 6 months after initial diagnosis. Cultured human cardiac fibroblasts (HCFs) were used as an in vitro model to study the functional and biological relevance of the gene target identified in the GWAS. Specifically, HCFs were transfected with siRNA by using the Lipofectamine™ RNAiMAX Transfection Reagent for gene knockdown (KD). RNA-seq was performed using the Illumina TruSeq protocol with expression analysis conducted with the EdgeR package. Ingenuity Pathway Analysis was used. Results A single-nucleotide polymorphism, rs11105445(G&gt;A), mapping to the neuron navigator 3 (NAV3) gene (rs11105445, p=2.37E-07; beta 2.74±0.53) was associated with improvement in LVEF. We performed a phenome-wide association study using data from the UK Biobank and demonstrated that genetic variation in NAV3 was significantly associated with HF mortality (p=3.2E-28), highlighting the potential importance of this gene in HF. Using GTEx data we demonstrated that in LV tissue the minor allele A was associated with ↓NAV3 expression (p=0.03) suggesting that ↓NAV3 expression might be associated with improvement in LVEF. We demonstrated that NAV3 KD significantly ↓TGF-β1 mediated HCF transdifferentiation into myofibroblasts, ↓α-smooth muscle actin (ACTA2) and ↓collagen I (COL1A1), therefore NAV3 KD was anti-fibrotic (see Figure 1), 1a. HCFs treated by vehicle/TGF-β1 after KD of NAV3/ctrl, and ACTA2 and COL1A1 were analyzed by qPCR; 1b. Representative immunofluorescence staining for α-SMA (in green), RNA-seq after NAV3 KD followed by pathway analysis suggested that NAV3 exerted its effect by regulating cell cycle related proteins (Figure 2), 2a. Volcano plot shows significant differentially expressed genes identified by RNA-seq analysis (down-regulated in blue, up-regulated in red); 2b. NAV3 KD significantly increased expression of cell cycle related proteins, which was validated by Western blot. Conclusions Decreased expression of NAV3 is associated with myocardial recovery in DCM, most likely due to its anti-fibrotic effect via direct regulation of cell cycle proteins. The role of NAV3 as a novel therapeutic target in DCM needs to be explored. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Mayo Clinic Center for Individualized MedicineMayo Clinic Department of Cardiovascular Medicine