bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 18303: Lrp1 Regulates Metabolic Activity by Binding PPAR Gamma in Endothelium
Authors: Mao Hua , Li Xi , Lockyer Pamela , Xie Liang , Pi Xinchun
Published: July 2021

Introduction:
The endothelium is a biologically active barrier and the site of metabolic exchange between the circulation and underlying tissues. Endothelial dysfunction is a common feature for obesity, dyslipidemia and diabetes and other vascular related diseases. Our recent studies demonstrate that low density lipoprotein receptor-related protein 1 (LRP1) impacts a variety of biological processes such as lipid metabolism, endocytosis and signal transduction. However, the role of LRP1 in endothelial cells remains a mystery.

Methods & Results:
The LRP1
flox/flox
(LRP1
f/f
) mouse was bred to Tie2-Cre transgenic mouse to have LRP1 deleted in ECs and hematopoietic cells, resulting in inactivation of LRP1 gene function in these cells only. Both the LRP1
f/f
;Tie2Cre
+
mice and wild type mice were fed with high fat diet for 16 weeks. The LRP1
f/f
;Tie2Cre
+
mice displayed a smaller increase in adipose tissue weight, liver weight and body weight , compared to wild-type mice following high fat food feeding. In addition, we discovered that adipocyte size is significantly smaller in LRP1
f/f
;Tie2Cre
+
mice than wild type mice. In addition, LRP1
f/f
;Tie2Cre
+
mice are more sensitive to insulin following a bolus of glucose, demonstrated with the decreased glucose level in serum. The LRP1
f/f
;Tie2Cre
+
mice also had decreased levels of circulating resistin, adiponectin and leptin compared to wild type mice. In LRP1
f/f
;Tie2Cre
+
mouse liver, there are much less deposition of lipid droplets than the wild type liver. The study of lipid profiles shows a much smaller increase in cholesterol and HDL levels. In cultured mouse endothelial cells (MECs), we discovered that LRP1 binds PPARγ, an important protein that is known to regulate endothelium function and contribute to the regulation of systemic metabolic responses. LRP1 positively regulates PPARγ activity and affects lipid handling gene induction in MECs.

Conclusions:
Taken all together, our data suggest that endothelial LRP1 regulates systemic metabolic events possibly through binding PPARγ and thereby modulating endothelial activation. It provides novel mechanistic insights for the metabolic roles of endothelial LRP1 and expands the functional roles of endothelium.
Abstract 18390: Effects of a Proprotein Convertase Subtilisin/kexin Type 9 (PCSK9) Inhibitor, Alirocumab, on Lipid and Lipoprotein Metabolism in Healthy Subjects
Authors: Reyes-Soffer Gissette , Pavlyha Marianna , Ngai Colleen , Thomas Tiffany , Holleran Stephen , Ramakrishnan Sekhar , Karmally Wahida , Donovan Daniel , Cowan Lisa , Sasiela William , Surks Howard , Rey Jacques , Poitiers Frank , Ginsberg Henry
Published: July 2021

Background:
Alirocumab is a monoclonal antibody that inhibits binding of PCSK9 to LDL receptors, decreasing their lysosomal degradation and increasing their numbers on cell surfaces. In Phase 2/3 studies, alirocumab 150 mg lowered LDL-cholesterol (C) ~61%, apoB 53%, and fasting triglycerides (TG) 16%. The mechanisms that increased LDL removal or the effects on postprandial (PP) TG levels after alirocumab therapy have not been reported.

Method:
18 (10F, 8 M), healthy volunteers completed a Phase 1, placebo-controlled, single-blind, single-sequence study. Subjects received 2 placebo doses followed by 5 alirocumab doses, 150 mg SC every 2 wks. At the end of each treatment period, we measured fasting lipids and lipoproteins and subjects received a high fat meal with PP TG and apoB48 levels measured over 8hrs. Stable isotope studies were performed 3-5 days later to measure apoB turnover in very low density (VLDL), intermediate density (IDL) and LDL.

Results:
In 18 subjects, Alirocumab significantly reduced plasma total-C by 35% (172±32 to 111±24 mg/dL), LDL-C by 60% (104±23 to 44±21 mg/dL) and, apoB by 45% (90±21 to 45±12 mg/dL). Plasma TG levels decreased by 13% (99±44 to 86±40mg/dL). LDL-C, LDL-TG, and LDL-apoB isolated from plasma by ultracentrifugation fell by 50±15%, 5±2%, and 41±16%, respectively, on alirocumab. Preliminary Kinetic results on N=10, show that the reductions in LDL-apoB were due to an increase in the fractional clearance rate (FCR) of LDL-apoB from 0.50±0.18 on placebo to 1.02±0.35 pools/day on alirocumab (p<0.001). IDL-C, IDL-TG and IDL-apoB were also reduced significantly, with a trend toward an increase in IDL-apoB FCR on alirocumab (placebo: 9.2±4 vs alirocumab: 10.8±3 pools/day; p=0.06). Alirocumab had no effects VLDL-C, VLDL-TG, or VLDL-apoB, nor did alirocumab change VLDL FCR or PR. The area under the curve for PP TG and PP apoB48 did not change from placebo to alirocumab. No serious adverse event or treatment discontinuation occurred. Results for all 18 subjects will be available for presentation.

Summary:
Alirocumab treatment significantly reduced levels of IDL and LDL-apoB by increasing the FCRs of these lipoproteins, particularly LDL. Alirocumab did not alter the metabolism of VLDL-apoB or PP TG-rich lipoproteins.
Abstract 18442: Cardiac-specific SOCS3 Deficiency Leads to Left Ventricular Dysfunction With Advanced Age Through Impaired Autophagy
Authors: Nohara Shoichiro , Yasukawa Hideo , Oba Toyoharu , Nagata Takanobu , Takahashi Jinya , Shimozono Koutatsu , Minami Tomoko , Ohshima Hideki , Kyogoku Sachiko , Fukui Daisuke , Mawatari Kazutoshi , Sugi Yusuke , Fukumoto Yoshihiro
Published: July 2021

Introduction:
Suppressor of cytokine signaling-3 (SOCS3) is a cytokine-inducible negative regulator of JAK-STAT signaling pathway. Cardiac-specific SOCS3 deficient mice (SOCS3-CKO) spontaneously develop cardiac dysfunction with advanced age.

Hypothesis:
We thus evaluated the underlying mechanism of age-related cardiac dysfunction in SOCS3-cKO mice.

Methods:
To create SOCS3-CKO mice, SOCS3-flox mice were bred with mice harboring a transgene encoding Cre recombinase driven by the α-myosin heavy chain promoter. Cardiac fibrosis was measured by Sirius-red staining. We evaluated autophagy induction by western blot using an antibody raised against microtubule-associated protein light chain 3 (LC3).

Results:
SOCS3-CKO mice were born at the expected Mendelian ratio, but developed cardiac dysfunction estimated by echocardiogram from 25 weeks of age. Cardiac fibrosis was greater in SOCS3-CKO mice compared to control mice (p<0.01). Western blot analysis revealed that increased activation of STAT3 from 25 weeks of age in SOCS3-CKO mice (p<0.01). TUNEL-positive cells were not observed in both control and SOCS3-CKO mice at 35 weeks of age. Expressions of Bax and Bad were comparable between control and SOCS3-CKO mice, indicating that apoptosis is not a main mechanism in the cardiac dysfunction with advanced age in SOCS3-CKO mice. In SOCS3-CKO mice hearts from 25 weeks of age, LC3II/LC3I ratio was significantly decreased (p<0.01). Western blot analysis revealed that expression of parkin and PINK1 but not p62 and Bnip3 were decreased in SOCS3-CKO mice compared with control mice from 25 weeks of age (p<0.01). We found that fasting-induced changes of LC3II/LC3I ratio were correlated with activation of STAT3 in WT mice hearts (p<0.01).

Conclusions:
These results suggest that age-related cardiac dysfunction in SOCS3-CKO mice may be due to impaired autophagy through sustained STAT3 activation.
Abstract 18503: Geranylgeranylacetone (gga) And Gga-derivatives Inhibit Acetylcholine-activated K+ Current In Mouse Atrial Cardiomyocyte ; Possible Mechanism For Af Suppression
Authors: Cha Tae-Joon , Choi Eun Kyoung , Yun Hye Jin , Yu Ga-In , Im Sung-Il , Brundel Bianca
Published: July 2021

Atrial fibrillation (AF) is the most common sustained arrhythmia. AF is caused by inflammation, oxidative stress, and various structural heart diseases. An important key factor in AF promotion is that atrial cardiomyocytes have constitutively active acetylcholine-activated K+ (IKACh) current that is enhanced by the tachycardia. Furthermore, it is known that heat shock proteins (HSPs) are involved in the protection against different forms of cellular stress and recent investigators reported that the HSP inducing compound geranylgeranylacetone (GGA, also known as teprenone) prevents atrial remodeling and attenuates the promotion of AF. Whether GGA and GGA-derivatives prevent the acetylcholine-activated K+ current is unknown.

Methods:
We examined the effect of HSP inducer GGA and 5 derivatives on IKACh current in mouse atrial cardiomyocytes. In the present study, the IKACh current was recorded using a nystatin-perforated whole cell patch-clamp technique following activation by acetylcholine (10 μM for 2 min). After the measurement of the baseline IKACh current, atrial cardiomyocytes were treated with GGA 10μM or a derivative of GGA (NYK9274, NYK9308, NYK9354, NYK9356 or NYK9376) for 10min and the IKACh current was re-measured.

Results:
IKACh current in mouse atrial cardiomyocyte treated with acetylcholine (10 μM) was significantly increased, which was markedly attenuated by GGA 10μM treatment (n=5, peak; 54±11.2%, quasi-steady-state; 58±11.4%, p<0.001). In addition, the effects of the GGA derivatives on IKACh were evaluated with same experimental protocol. Our results showed that next to GGA, also NYK9308 and NYK9356 significantly inhibit both peak and quasi-steady-state IKACh. In contrast, NYK9274, NYK9354 and NYK9376 had no effect on IKACh.

Conclusion:
This study provides important evidences that the HSP inducer GGA facilitates its potent antiarrhythmic effect by inhibiting IKAch, which underlies electrical remodeling in mammalian atrial cardiomyocytes. Furthermore, two GGA derivatives, NYK9308 and NYK9356, with improved pharma-chemical properties compared to GGA, reveal similar protective effects compared to GGA, and provide important background information for the use of GGA and GGA-like compounds in patients with AF.
Abstract 18648: Suspected Acute Coronary Syndrome With Normal Coronary Arteries: The Value of Cardiac Magnetic Resonance in Changes of Treatment
Authors: Soeiro Alexandre M , Nakamura Débora Y , Leal Tatiana C , Bossa Aline S , Soeiro Maria C , Serrano Jr Carlos V , Oliveira Jr Múcio T
Published: July 2021

Introduction:
Acute chest pain, ST-changes on EKG and elevation of cardiac troponin in patients without obstructive coronary artery disease represent a clinical challenge. Cardiovascular magnetic resonance (CMR) can be used to diagnose causes other than obstructive coronary artery disease. Hypothesis: The aim of this study was to evaluate the usefulness of CMR to diagnose conditions in the emergency room that otherwise would be considered as acute coronary syndrome (ACS) in patients with normal coronary arteries.

Methods:
Fifty-nine patients with chest pain and/or electrocardiographic changes and elevated troponin concentration occurring in the absence of significant coronary artery stenosis (normal or stenosis < 50% of the vessel diameter on angiography, computed tomography or both) were selected and prospectively submitted to CMR exam in a 1.5T Philips scanner between May 2013 and December 2014. Ventricular function by cine MR with SSFP technique, and myocardial tissue characterization using late gadolinium enhancement (LGE) were evaluated in patients referred to the Emergency room. LGE patterns were analyzed visually by 2 observers and classified as ischemic (involving subendocardial layer) and nonischemic (multifocal, not involving subendocardial layer, non coronary distribution).

Results:
Among 59 patients, all with interpretable CMR exams, diagnosis of acute myocarditis was found in 39% of patients, acute myocardial infarction in 17% and Takotsubo cardiomyopathy in 12%. Other final diagnoses were hypertrophic cardiomyopathy (5%), coronary embolism (10%), cardiomyopathy (3%), sepsis (4%), aortic stenosis (3%) and non-compaction myocardium (2%). In 38 patients (66%), CMR changed the initial ACS diagnosis to another final diagnosis. Additionally,3 patients primarily considered as having myocarditis received a final diagnosis of myocardial infarction. Conclusions: In the study, 66% of patients had their primary diagnosis and treatment changed after CMR study. The presence, distribution and pattern of late gadolinium enhancement by CMR were crucial in establishing a precise final diagnosis and appropriately changing patient management.
Abstract 18689: Lower Carotid Artery Compliance and Greater Carotid β-stiffness Index are Associated With Slower Processing Speed and Reduced Working Memory Performance in Older Healthy Adults
Authors: DuBose Lyndsey E , Voss Michelle W , Weng Timothy B , Dubishar Kaitlyn M , Lane-Cordova Abbi , Sigurdsson Gardar , Schmid Phillip , Pierce Gary L
Published: July 2021

Introduction:
Higher central elastic artery stiffness is associated with greater brain white matter hyperintensity volume and lower cognitive performance in older adults. However, it is unknown if higher central artery stiffness is related to regional decreases in brain white matter integrity (WMI) and reductions in working memory or processing speed. We hypothesized that greater large elastic artery stiffness would be associated with lower working memory and slower processing speed as well as lower regional WMI in older adults.

Methods:
In young (n=19; 23.8 ± 0.7 yrs) and older (n=22; 64.4 ± 4.2 yrs; range 60-71 yrs) healthy adults, aortic stiffness (carotid-femoral pulse wave velocity, cfPWV, via tonometry) and carotid artery compliance and β-stiffness index (carotid artery ultrasound and tonometry) were determined non-invasively. WMI was assessed by fractional anisotrophy (FA) (3T MRI) from diffusion tensor images. An N-Back task and letter and pattern comparison tests were performed as measures of working memory and processing speed, respectively. d’Prime, a measure of signal detection, was calculated on the N-Back task as a ratio of positive ‘hits’ to ‘false alarm’ responses.

Results:
cfPWV (8.4 ± 0.5 vs. 5.2 ± 0.2 m/sec, P<0.01) and carotid β-stiffness (11.3 ± 0.9 vs. 6.1 ± 0.7 U, P<0.01) were greater and carotid compliance (0.16 ± 0.02 vs. 0.07 ± 0.01 mm/mmHg, P<0.01) was lower in older vs. young adults. Carotid β, but not aortic, stiffness was associated with slower processing speed on letter (10.7 ± 0.5 vs. 13.5 ± 0.6 units/ 30 sec, p<0.01) and pattern (16.6 ± 0.6 vs. 22.0 ± 0.7 units/30 sec, p<0.01) comparison tasks and reduced working memory (1.8 ± 0.2 vs. 3.1± 0.2, P<0.01) in older vs. young adults. Lower carotid compliance was associated with slower performance on the letter (r=0.55, P<0.01) and pattern (r=0.54, P<0.01) tests and lower d’Prime (r=0.48, P<0.05). Greater β-stiffness was related to pattern comparison scores only (r=-0.54, P<0.01). Aortic stiffness, carotid compliance and β-stiffness were not related to WMI in any brain region.

Conclusions:
Our results suggest that lower carotid artery compliance and greater β-stiffness are associated with reduced working memory performance and slower processing speed but not regional WMI in older adults.
Abstract 18705: BRCA2 is a Novel Regulator of Endothelial Cell Function and Apoptosis
Authors: Matkar Pratiek N , Cao Wei J , Al-Omran Mohammed , Verma Subodh , Leong-Poi Howard , Singh Krishna K
Published: July 2021

Background:
Germ-line mutations in the tumor suppressor gene BRCA2 (breast cancer 2, early onset) predispose carriers not only to breast cancer, but also to other cancers. BRCA2 plays crucial role in the genome integrity maintenance and is central to DNA-damage repair. BRCA2-associated DNA-damage responses are not only specific to cancer syndromes but also represent a common pathophysiological basis for diverse cardiovascular diseases (CVDs). These observations led us to hypothesize that BRCA2 is an essential regulator of endothelial function and apoptosis following genotoxic stress.

Methods:
To elucidate the role of BRCA2 in endothelial cells, we silenced BRCA2 in the human umbilical vein endothelial cells (ECs) and measured the indices of EC function; tube formation and proliferation, DNA-damage/repair and apoptosis by qPCR, immunoblotting and immunofluorescence following doxorubicin (Dox) treatment.

Results:
We confirmed the basal expression and successful silencing of BRCA2 in ECs at transcript and protein levels by qPCR and immunoblotting, respectively. Genotoxic stress in the form of Dox exacerbated DNA-damage in BRCA2-silenced ECs as evident by increased expression and activation of DNA double-stranded breaks (DSBs) marker H2A.X and reduced RAD51-foci formation, an essential regulator of DSB repair. Increased DSBs were associated with significantly increased expression and activation of p53, and increased expression of p53-upregulated modulator of apoptosis PUMA. Elevated levels of DNA-damage and p53 were further associated with significantly increased Dox-induced apoptosis in BRCA2-silenced ECs as measured by immunoblotting for cleaved-caspase-3 and TUNEL-staining.Key indices of endothelial function, including tube formation and proliferation, were significantly reduced following Dox-treatment in BRCA2-deficient ECs, which was accompanied with significantly increased expression of cell cycle inhibitor, p21 at transcript and protein levels.

Conclusion:
Our data for the first time, show an entirely novel role of BRCA2 as a regulator of endothelium, and provide important clues regarding a potential susceptibility of BRCA2 mutation carriers to anthracycline-induced CVDs, a cornerstone of chemotherapy for cancer.
Abstract 18718: Trends, Predictors, and Regional Variation in Use of Catheter Ablation Among 184,443 Hospitalizations for Ventricular Tachycardia
Authors: Tzou Wendy S , Katz David F , Aleong Ryan G , Sauer William H , Kao David P
Published: July 2021

Introduction:
Catheter radiofrequency ablation (RFA) is used increasingly for treatment of ventricular tachycardia (VT), but little is known about utilization patterns.

Hypothesis:
Regional trends in VT hospitalization and RFA,and patient characteristics associated with VT RFA vary.

Methods:
Hospital discharge data was obtained from state agencies in California, New York, New Jersey, Vermont, New Hampshire, West Virginia, Colorado, and Texas from 1994-2012. All records with primary diagnosis of VT (ICD9-CM 427.1) were analyzed. Population-adjusted hospitalization rates were estimated using US Census Bureau data. In hospitals performing VT RFA, patient characteristics associated with RFA were identified using multivariate logistic regression.

Results:
In total, 184,443 hospitalizations for VT were reported; 11,941/136,437 (8.8%) admitted to VT ablation hospitals underwent RFA. Annual VT hospitalization rates varied from 10-17/100,000 in California (CA) and Texas (TX) to 20-30 in New York and New Jersey (NJ). VT ablation/hospitalization frequency varied from 9% in NJ to 18% in CA and TX. Positive predictors of undergoing VT RFA were female gender, non-white race, admission from home, and atrial flutter. Negative predictors included advancing age, non-private insurance, atrial fibrillation, anemia, coronary artery disease, heart failure, hypertension, and shock on admission (Figure, A). Higher RFA rates for women were driven by more patients without structural heart disease compared to men (Figure, B). Non-white patients were more likely to undergo RFA irrespective of structural heart disease.

Conclusion:
Significant regional variations exist in VT hospitalization and ablation rates. Also of note, women and non-white patients were more likely to undergo ablation, which may have reflected important differences in cardiac disease substrate.
Abstract 18835: Chromatin Gene Cohorts, Not Individual Cardiac Genes, Modulate Cardiac Phenotype in a Genetically Diverse Population
Authors: Karbassi Elaheh , Monte Emma , Lopez Rachel , Kim Joseph , Chapski Doug , Rau Christoph , Wang Jessica , Weiss James N , Wang Yibin , Lusis Aldons J , Vondriska Thomas M
Published: July 2021

Re-expression of fetal genes is a hallmark of transcriptome change in models of cardiac hypertrophy, but how this remodeling is affected by the common genetic variation present in populations is unknown. We examined gene expression in 86 strains of control and isoproterenol (ISO)-treated mice, which exhibited varying degrees of disease. Correlations between individual fetal genes (Anf, Serca2a, alpha-MHC, beta-MHC) and hypertrophic phenotypes were not significant. Expanded analysis of 37 fetal genes showed sparse correlation (at p<0.05) between expression of individual genes with one or more of 52 systemic phenotypes. We next tested the hypothesis that groups of genes exhibit emergent association with phenotype not observed with individual transcripts. Examining the fetal genes as a group unmasked a correlation with left atrial mass (enriched 3.04-fold vs transcriptome, p<0.001). Grouping cardiac transcription factors (n=31 genes) or genes shown by gain/loss of function studies to contribute to hypertrophic signaling (n=142) revealed no correlation to cardiac phenotypes, whereas chromatin regulators (n=124) were associated with right ventricular mass (1.55-fold, p<0.01), fractional shortening (1.52-fold, p<0.05) and ejection fraction (1.50-fold, p<0.05).

We next analyzed histone genes. HOPACH clustering generated 39 clusters of strains based on the basal transcriptome that collapsed to 13 clusters after ISO, suggesting that adrenergic stress entrains gene expression. We observed transcriptional co-regulation of H2A with H2B, and H3 with H4 (the other pairings did not show correlation), mirroring the protein level assembly, which proceeds via pairs of dimers according to the same logic. Comparison of strain grouping based on partitioning clustering using histone stoichiometry or phenotype revealed that hypertrophic mice were enriched in histone cluster 4, marked by minimal change to histone variant expression (enriched 2.27-fold, p<0.01). The two novel conclusions are: fetal gene regulation is buffered within populations by common genetic variation and is not a good predictor of disease; and cardiac phenotype is influenced in the basal and disease states through global changes in chromatin.
Abstract 18873: Al
18
F-NOTA-folate Accumulates in Atherosclerotic Plaques and Can be Detected by PET/CT
Authors: Silvola Johanna M , Li Xiang-Guo , Virta Jenni , Prasad Padmasola Guru , Marjamäki Päivi , Liljenbäck Heidi , Tarkia Miikka , Hytönen Jarkko , Saunavaara Virva , Ylä-Herttuala Seppo , Chen Qingshou , Low Philip S , Knuuti Juhani , Saraste Antti , Roivainen Anne
Published: July 2021

Introduction:Macrophages are a major cell type in inflamed atherosclerotic plaques. Since folate receptor β (FR-β) is highly expressed in activated macrophages, we hypothesized that it might serve as a new marker for inflamed atherosclerotic plaques.

Hypothesis:
We aimed at evaluating a FR-β targeted PET tracer, Al
18
F NOTA-Folate, for the detection of inflamed atherosclerotic plaques.

Methods:Atherosclerotic mice deficient for low density lipoprotein receptor (LDLR
-/-
ApoB
100/100
, n=12), C57BL control mice (n=9), and Watanabe rabbits (n=4) with endothelial denudation-induced atherosclerosis in the aorta were used. Biodistribution of Al
18
F-NOTA-Folate (specific radioactivity 130 GMq/μmol) was investigated
in vivo
by PET/contrast enhanced CT and
ex vivo
by gamma counting and autoradiography of aortic sections. In addition, prior to Al
18
F-NOTA-Folate study, the Watanabe rabbits were PET/CT imaged with
18
F-FDG.

Results:Atherosclerotic mice demonstrated large and macrophage-rich atheromatous plaques in the aorta. The
in vivo
PET/CT revealed significantly higher uptake of Al
18
F-NOTA-Folate in the aortic arch of atherosclerotic mice compared to controls (aorta-to-blood ratio 1.5±0.3 vs. 0.7±0.2,
P
<0.0001), which were verified by
ex vivo
measurements. Autoradiography confirmed focally increased uptake of Al
18
F-NOTA-Folate in the atherosclerotic plaques (plaque-to-normal vessel wall ratio 2.6±0.7,
P
<0.0001). Competitive study with excess of unlabelled folate reduced Al
18
F-NOTA-Folate uptake in the aorta by app. 80% and thus verified the specificity of its binding. In the rabbit aorta, the PET/CT showed a strong focal
in vivo
uptake of Al
18
F-NOTA-Folate co-localizing with an atherosclerotic abdominal aorta with highest aorta-to-blood ratio of 6.0. For comparison, with
18
F-FDG the ratio was 2.4 in the same area.

Conclusions:
Al
18
F-NOTA-Folate, targeting FR-β, accumulates in macrophage-rich atherosclerotic plaques, which can be detected
in vivo
by PET/CT in experimental models of atherosclerosis. Further development of the tracer for imaging of patients with atherosclerosis is warranted.
Abstract 18922: Radiofrequency Catheter Ablation Reduces Diffuse Myocardial Fibrosis in Atrial Fibrillation
Authors: Suksaranjit Promporn , Wilson Brent D , McGann Christopher J , Kholmovski Eugene G , Haider Imran , Marrouche Nassir F
Published: July 2021

Introduction:
Atrial fibrillation (AF) is associated with diffuse myocardial fibrosis as quantified by cardiac magnetic resonance (CMR) using T1 mapping methods. Radiofrequency catheter ablation (RFCA) is evolving, and the role in rhythm control may be ideal for reversing left ventricular (LV) remodeling.

Hypothesis:
We aimed to study the impact of RFCA on diffuse myocardial fibrosis in AF patients.

Methods:
We retrospectively collected data from consecutive AF patients who underwent RFCA with modified Look-Locker Inversion recovery T1 mapping sequences on pre/post procedural CMR at 3.0-Tesla. Precontrast T1 relaxation time of the mid-LV short-axis view was used as an index of diffuse LV fibrosis. Primary outcome was the change in diffuse LV fibrosis after RFCA.

Results:
A total of 11 patients (mean age 67 years, 72% male, 67% paroxysmal AF) were enrolled. Median AF duration was 24.6 months [Interquartile range (IQR): 13.3-45.3)] and median CHA2DS2-VASc was 2 [IQR: 1-3]. Post RFCA CMR was obtained 99.5±18.1 days after the RFCA procedure. Mean precontrast T1 time was significantly lower after RFCA (1182ms vs 1158ms; p=0.0157).

Conclusions:
Based on our preliminary results, RFCA in AF reduces diffuse myocardial fibrosis and may play a role in reverse LV remodeling.
Abstract 19030: High Mortality in Cardiomyopathy Patients Heterozygous for the CFTR ΔF508 Cystic Fibrosis Mutation
Authors: London Barry , Boudreau Ryan , Halder Indrani , Vargas-Estrada Andres , Comellas Alejandro , Johnson Frances L , Zabner Joseph , Gutmann Rebecca A , Bloom Heather L , Dudley Samuel C , Ellinor Patrick T , Shalaby Alaa , Weiss Raul
Published: July 2021

Introduction:
Cystic fibrosis is among the most common inherited disorders, with ∼ 3% of Caucasians being heterozygous for the common
CFTR
ΔF508 mutation. Cardiomyopathy is a major cause of morbidity and mortality. While a small preliminary study suggested that cardiomyopathy patients heterozygous for the
CFTR
ΔF508 mutation have poorer outcomes, the finding has not been replicated and it is not known whether the poor outcomes are related to sudden death and/or heart failure progression.

Methods:
We screened 1347 Caucasian cardiomyopathy subjects (EF 21%, 82% male, 75% ischemic) with implantable cardioverter defibrillators (ICDs) from the prospective, multicenter, NIH-funded Genetic Risk Assessment of Defibrillator Events (GRADE) study. CFTR ΔF508 alleles were discriminated by real time fluorescence PCR. GRADE subjects were followed for up to 5 years to the primary endpoint of freedom from appropriate ICD shocks and the secondary endpoints of death and death/heart transplant/VAD placement. The results were compared by genotype using Kaplan-Meier analysis and Log Rank testing.

Results:
Genotyping revealed 33 CFTR ΔF508 heterozygotes (allele frequency 2.4%). ΔF508 carriers were older (68 vs 64 yrs, p=0.03); more likely to be diabetic (55 vs 34%, p=0.02), to have had an MI (77 vs 57%, p=0.02), and to have a RBBB on ECG (18 vs 7%, p=0.03); and had lower EFs (19 vs 21%, p=0.01). CFTR ΔF508 carriers had markedly higher rates of death (HR>2; p<0.001) and death/VAD/transplant (p=0.004), with no difference in appropriate ICD shocks (Figure).

Conclusion:
We have confirmed that carrying one CFTR ΔF508 allele is associated with an increased mortality in cardiomyopathy patients, and that this is likely not due to increased arrhythmic death. These findings may have implications for the treatment of this high risk heart failure subgroup. Future studies are needed to determine whether the increased mortality stems from a cardiac and/or pulmonary etiology.
Abstract 19065: Circulating Cells Contribute to Post-infarction Myocardial Repair by Adopting Mature Cardiomyocyte and Endothelial Cell Fates
Authors: Burnett Cassandra E , Goldstone Andrew B , Cohen Jeff E , Patel Jay B , Edwards Bryan E , Eskandari Anahita , Ong Sang-Ging , MacArthur John W , Shizuru Judith A , Woo Joseph
Published: July 2021

Objective:
Whether bone marrow derived circulating cells engraft in ischemic myocardium and adopt non-hematopoietic fates remains controversial. Discordance may result from limitations of parabiosis models for fate tracking. Using a bone marrow chimera model, we hypothesized that circulating cells do, in fact, contribute to mature vessel formation and myocardial regeneration.

Methods:
Recipient C57BL/6 (n=16) or C57BL/6-GFP mice (n=13) were lethally irradiated (10 Gy) and transplanted with 5x10
6
whole bone marrow cells from C57BL/6-DsRed donors. Four weeks post transplant, animals underwent acute myocardial infarction (MI) by ligation of the left anterior descending artery. Hearts were explanted 3 weeks post MI and were examined histologically. Individual cells were sorted after Langendorff isolation with FACS (Fig 1A).

Results:
Bone marrow transplant reproducibly yielded >90% chimerism in peripheral blood and in the hematopoietic stem cell population. The majority of DsRed+ circulating cells adopted mature hematopoietic fates in ischemic myocardium, of which 82.3±1.54% were CD11b monocytes. However, DsRed+ circulating cells directly contributed to mature vessel formation, incorporating as cells expressing the endothelial markers, CD31 and von Willebrand factor (Fig 1B). In fact, 1.85±0.36% of the isolated CD31+ cells expressed DsRed. Fate tracking also demonstrated that circulating cells facilitate myocardial regeneration (Fig 1C) through cell fusion with native cardiomyocytes (0.03±0.01%), and to a lesser extent through transdifferentiation (0.00043±0.00029%).

Conclusions:
Bone marrow derived circulating cells engraft in the ischemic heart and directly repair myocardium by adopting mature endothelial and cardiomyocyte fates. Mechanistic insight into the endogenous governance of circulating cell transdifferentiation and fusion post MI is essential to realizing the full potential of cytokine and progenitor cell based therapies.
Abstract 19144: Echocardiographic Assessment of Structural and Hemodynamic Changes in Hypertensive Pregnancy
Authors: Kim Mi-Jeong , Cho Kyoung-Im , Yoon Se-Jung , Choi Jung-Hyun , Shin Mi-Seung
Published: July 2021

Introduction:
Pregnancy induces dramatic cardiovascular changes to meet the metabolic needs for mother and fetus. Eccentric left ventricular hypertrophy (LVH) is known as the normal cardiac response to handle the increasing circulatory volume during pregnancy. Cardiac adaptation would be modified in pregnancy complicated by hypertension.

Methods:
Data from 193 consecutive pregnant women were analyzed. Clinical and echocardiographic data were compared in normotensive and hypertensive women.

Results:
Left ventricular mass index was significantly higher in hypertensive women than normotensive ones (87±17 vs 78±16, p<0.001, Fig.1A). Diastolic function measured by the ratio of early mitral blood to annular velocity (E/E’) was impaired in hypertensive women (11.0±3.0 vs 9.2±2.5, p<0.001, Fig.1B). Such change was more prominent in women with gestational hypertension (GHW) than those with chronic hypertension (CHW). Obesity was independent factor associated with LVH in both normotensive and hypertensive women (Fig.1C). Overt eccentric LVH was more frequent than concentric remodeling/hypertrophy (25% vs 8.4%) in GHW, while the result was opposite in CHW (14% vs 23%, Fig.1D).

Conclusion:
Hypertensive pregnancy is associated with significant LVH and diastolic dysfunction. Obesity accentuates hypertension-related cardiac remodeling. While eccentric LVH is prominent in GHW, pre-existing chronic hypertension appears to induce concentric LV geometry.
Abstract 19165: Regional Changes in Cellular and Molecular Pathology in Children With End-stage Dilated Cardiomyopathy: Correlation With Cardiac Performance
Authors: Chen Ching Kit , Sun Mei , Slorach Cameron , Ishii Ryo , Redington Andrew N , Friedberg Mark K
Published: July 2021

Dilated cardiomyopathy (DCM) carries poor prognosis in children, often needing heart transplant. Regional differences in left ventricular (LV) function suggest inhomogeneous expression of contractility related proteins. However, associations between myocardial performance and histological / molecular findings are poorly defined.

We sought to investigate associations of regional myocardial performance with histological and molecular changes in hearts explanted from children with DCM, undergoing transplantation.

Clinical and echo features (including tissue Doppler and strain) were correlated with histological and molecular findings in hearts explanted from 9 children [median age 2.8 years (range 4.4 months-17 years); 6 had LVAD]. Interstitial fibrosis, myocyte volume, and expression of proteins (western blot) implicated in fibrosis and function (
p38
,
ERK
, phospho-
JNK
, phospho-
GSK
,
SMA
, myosin heavy chain, cadherin,
ILK
, sarcoplasmic reticulum Ca
2+
-ATPase [SERCA2a], phospho-
CamKII
, phospholamban [PLN], and phospho-PLN) were correlated with speckle tracking strain from 11 regions per patient (basal and mid regions of anterior septum, anterior, lateral, posterior and inferior LV segments, and right ventricular [RV] free wall).

On average, no significant difference was noted for the percentage of fibrosis and myocyte volume between the various LV segments, and between RV and LV. LV dimension, systolic and diastolic function were not related to interstitial fibrosis, myocyte volume or molecular signaling. Tricuspid annular plane systolic excursion was related to myocyte volume (r=0.89;
p
<0.01). An inverse relationship between the extent of interstitial fibrosis and segmental longitudinal strain was present for LV basal and mid posterior segments (basal posterior, r=0.96,
p
<0.01; mid posterior, r=0.74,
p
=0.05). Global longitudinal strain was related to expression of ILK and SERCA2a (ILK, r=0.78,
p
=0.02; SERCA2a, r=0.71,
p
=0.04).

This study demonstrated association of regional cardiac function in children with DCM with expression of calcium-cycling and contractile proteins, as well as interstitial fibrosis. These findings have implications for diagnosis and therapeutic targets in pediatric DCM.
Abstract 19170: Lesion Morphological Classification by Optical Coherence Tomography to Predict Therapeutic Efficacy After Balloon Pulmonary Angioplasty
Authors: Inohara Taku , Kawakami Takashi , Kataoka Masaharu , Fukuda Keiichi
Published: July 2021

Introduction:
Conventionally, angiographic classification has been used for chronic thromboembolic pulmonary hypertension (CTEPH). However, a classification based on lesion morphology is needed in the era of balloon pulmonary angioplasty (BPA). We sought to propose a classification of CTEPH based on lesion morphology detected by optical coherence tomography (OCT) and to evaluate its association with physiological stenosis assessed with a pressure wire and therapeutic efficacy in BPA.

Methods:
We analyzed 43 lesions in 17 patients who were treated with BPA under OCT and pressure-wire guidance from November 2012 to March 2015. OCT findings were classified into the following 4 categories: 1) mono-hole, 2) septum, 3) multi-hole with thin wall, and 4) multi-hole with thick wall.

Results:
Angiographic findings did not match the specific morphologic classification based on OCT findings. At the pre-BPA assessment, the pressure ratio of the septum type was significantly higher than that of the mono-hole and multi-hole with thick wall types (p = 0.026 and 0.047, respectively). Under the OCT-based classification, more than 50% of the septum and multi-hole with thin wall types could accomplish >0.8 of the mean pressure ratio assessed by a pressure wire, and these proportions were significantly higher than those of the other 2 types: mono-hole and multi-hole with thick wall (p = 0.044). Based on angiographic classification, accomplishment of this criterion was not significantly different among angiographic types.

Conclusions:
OCT-based morphologic lesion classifications in CTEPH were useful to predict whether the lesion stenosis could improve to the acceptable level mediated by BPA.
Abstract 19179: Effects of Systemic Insulin Resistance on Redox State and Endothelial Nitric Oxide Bioavailability in the Human Vascular Wall
Authors: Akoumianakis Ioannis , Margaritis Marios , Psarros Constantinos , Herdman Laura , Antonopoulos Alexios , Petrou Mario , Krasopoulos George , Wohlfart Paulus , Channon Keith , Antoniades Charalambos
Published: July 2021

Background:
Insulin resistance (IR) and diabetes mellitus (DM) are associated with increased risk of cardiovascular disease. We explored the specific effects of insulin resistance on vascular redox state and endothelial function in non-diabetic patients with coronary atherosclerosis.

Methods:
The study population consisted of 383 patients undergoing coronary bypass surgery (CABG). Endothelial function was estimated using non-invasive imaging (brachial Flow-Mediated Dilatation -FMD) preoperatively. During surgery, segments of human saphenous vein (SV)were obtained and used to quantify nitric oxide bioavailability (ex vivo vasorelaxations in response to acetylcholine) and NADPH oxidase-derived superoxide (O2-) by lucigenin chemiluminescence (using NADPH at 100μM). Glucose and insulin were measured in plasmas for calculation of HOMA-IR, the homeostatic model assessment of IR status.

Results:
The presence of IR (HOMA-IR>2.9) was associated with impaired FMD (A), reduced vasorelaxations of human vessels in response to acetylcholine (B) and elevated vascular O2- generation (C).

Conclusions:
IR is associated with impaired endothelial function and increased oxidative stress in human vessels. This is the first study demonstrating a direct effect of systemic insulin resistance on key mechanisms of atherogenesis in human vessels, highlighting it as a specific therapeutic target in non-diabetic patients with atherosclerosis.
Abstract 19279: Rescue Of D2R Function in Mouse Kidney Using AAV9 Vector Abrogates the Renal Injury and High Blood Pressure Induced by D2R Silencing
Authors: Konkalmatt Prasad , Asico laureano D , Yang Yu , Drachenberg Cinthia B , Jose Pedro A , Armando Ines
Published: July 2021

In humans decreased dopamine D2 receptor (D2R) expression and function is associated hypertension and inflammation and fibrosis in renal proximal tubule cells. In mice selective D2R silencing in the kidney results in renal inflammation, injury and hypertension. We hypothesized that these alterations are ameliorated by rescue of renal D2R function. To test this hypothesis we silenced renal D2R expression by sub-capsular infusion of D2R siRNA (D2RsiRNA) using osmotic mini pumps (3 μg/day, n=6 per group). Mice treated with non-silencing siRNA (NS siRNA) served as controls. Two weeks after starting siRNA treatment, mice were treated with control AAV (CAAV) or AAV carrying wild-type D2R (D2RAAV) (n=3 per group, 1e+11 vgp/mouse). Two weeks following AAV treatment, blood pressure was measured and organs were collected. D2R expression was decreased in D2RsiRNA-treated kidneys compared with NSsiRNA-treated kidneys (54 ± 0.8 vs 100± 22 %; P<0.05). D2RAAV treatment increased D2R expression (7.5-11-fold; P<0.01) in both D2RsiRNA and NS siRNA-treated mice. Mice with silenced D2R expression (D2RsiRNA+CAAV) had increased systolic blood pressure (121±3 mmHg; P<0.05) in comparison with the D2R rescued group ( D2RsiRNA+D2RAAV) (100±6 mm Hg), NSsiRNA+CAAV (101±4 mm Hg), or NS siRNA +D2RAAV (101±1 mm Hg). D2R silencing caused an increase in the expression of TNF-α, TGF-β1 and its downstream target fibronectin-1, as well as kidney injury molecule-1 and ki-67, a marker of cell proliferation. By contrast, the expression of these proteins was decreased or reversed to normal in the D2R-rescued group. Masson trichrome staining showed tubular atrophy, interstitial fibrosis and extensive areas of scaring in D2R silenced mice while these abnormalities were significantly reduced in the D2R rescued group. T cells infiltration was significantly higher in D2R silenced group compared to the D2R-rescued group (309 ± 38 vs 217± 17 %; P<0.05). These results show that D2R re-expression prevented the progression of the lesions and demonstrate that increased blood pressure and renal injury due to D2R silencing could be rescued by over expression of D2R in the kidney using AAV9 vector. Furthermore, these data provide the basis for designing novel therapies for kidney disease.
Abstract 19282: Transient Bone Morphogenic Protein Antagonism Directs Differentiation of Ipscs Into the Cardiac Neural Crest and Ckit+ Myocardial Progenitor Lineages
Authors: Hatzistergos Konstantinos E , Takeuchi Lauro M , Saur Dieter , Seidler Barbara , Dymecki Susan M , Mai Jia Jia , Takeuchi Rosemeier K , Balkan Wayne , Hare Joshua M
Published: July 2021

Introduction:
The signaling pathways that govern cKit+ cardiac progenitor cell (CPC) differentiation into cardiomyocytes (CMs) are unknown. Some studies suggest an essential role in cardiomyogenesis, others suggest a minimal CPC contribution. We studied if it is a non-permissive cardiac milieu that minimizes the generation of CMs from CPCs.

Hypothesis:
Transient BMP antagonism directs the generation of cardiomyocytes from CPCs.

Methods:
We lineage-traced CPCs using a novel dual-recombinase responsive indicator mice (cKitCreERT2;Wnt1::Flpe;RC::Fela) and iPSCs derived from cKitCreERT2;IRG (iPSCKit) mice.

Results:
Intersectional genetic fate-mapping of cKitCreERT2;Wnt1:: Flpe;RC::Fela embryos supported that cKit marks Wnt1-expressing cardiac neural crest (CNC) progenitors, emerging at ~E9.5 and contributing a limited number of cardiomyocytes (n=3). We lineage-traced CPCs during stage-specific cardiogenic differentiation of iPSCKit. Ascorbate treatment promoted differentiation of iPSCKit-derived embryoid bodies (EBs) into Nkx2.5+ myocardium, 45.5%±6.7% of which co-expressed the Cre-reporter EGFP (n=154 EBs; 12 preps), suggesting that CPCs encompass fully competent cardiomyogenic progenitors. Noggin (or Dorsomorphin), a BMP antagonist transiently expressed in the heart at E7.5-E8.5 but not during CNC invasion, directed the differentiation of iPSCkit-EBs into Mesp1+/Isl1+/Nkx2.5+ cardiac mesoderm progenitors (p≤0.0001). The same signaling pathway subsequently directed EBs into the cKit+/Wnt1+/Pax3+/Mitf-H+/Isl1+/Nkx2.5+ CNC lineage (p≤0.0001), while suppressing the generation of WT1+/Tbx18+ epicardium (p<0.05). Stage-specific induction of Cre-recombination delineated that iPSCkit-derived CPCs encompass Mesp1–/cKit+/Nkx2.5+ CNC progenitors, which contributed EGFP+ CNC derivatives, including Nkx2-5+ cardiomyocytes, to 60.7%±7.3% of spontaneously beating EBs (n=147 EBs; 12 preps).

Conclusions:
Our data show that CPCkit are fully competent CNC-derived cardiomyogenic progenitors, whose differentiation to cardiomyocytes is minimized by a latent Noggin-mediated signaling pathway. Therapeutically exploiting CPCkit, provides an important strategy for maximizing myocardial regeneration.
Abstract 19292: KLF4 Regulates Mitochondrial Homeostasis in the Heart
Authors: Liao Xudong , Jain Mukesh
Published: July 2021

Mitochondrial homeostasis is critical for heart function and mitochondrial dysfunction contributes to numerous heart diseases such as heart failure. Our previous work indicates that mice with cardiomyocyte-restricted deficiency of KLF4 develop heart failure precipitously in response to pressure-overload but the underlying mechanisms remain unknown. We hypothesized that KLF4 may regulate mitochondrial function in the heart. Here we show that KLF4 governs mitochondrial biogenesis, metabolic function, dynamics and autophagic clearance. Adult mice with cardiac-specific KLF4 deficiency develop cardiac dysfunction with aging or in response to pressure overload characterized by reduced myocardial ATP levels, elevated ROS, and marked alterations in mitochondrial heterogeneity and alignment. Studies in mitochondria isolated from KLF4-deficient hearts revealed reduced respiration rate likely due to defects in ETC Complex I. Further, embryonic cardiac KLF4 deletion resulted in postnatal premature mortality, impaired mitochondrial biogenesis, and altered mitochondrial maturation. Mechanistically, we show that KLF4 binds to, cooperates with, and is requisite for optimal function of the ERR/PGC-1 transcriptional regulatory module on metabolic and mitochondrial targets. Finally, KLF4 also regulates autophagy through transcriptional control of a broad array of autophagy genes in cardiomyocytes. Collectively, these findings identify KLF4 as a nodal transcriptional regulator of mitochondrial homeostasis.
Abstract 19302: Long Term High Endurance Exercise and the Heart: Too Much of a Good Thing?
Authors: Merghani Ahmed , Maestrini Viviana , Rosmini Stefania , Dhutia Harshil , Cox Andrew , David Sarojini , Narain Rajay , Malhotra Aneil , Kaski Juan C , Alfakih Khaled , Moon James , Sharma Sanjay
Published: July 2021

Introduction:
The benefits of regular moderate exercise are well documented, however, there is a burgeoning group of veteran athletes who have been exercising vigorously since youth and the impact of life long intensive exercise on the heart is unknown.

Hypothesis:
Life-long intensive exercise may promote adverse cardiac remodelling.

Methods:
A large cohort of veteran athletes and gender, age and Framingham matched controls were studied comprehensively to investigate any detrimental effects of chronic life-long intensive exercise among veteran athletes. Veteran athletes were defined as >40 years of age and having competed in multiple endurance events over a 10 year period. Controls were recruited from University staff. All individuals were subjected to a cardiopulmonary exercise test, 24 hour Holter monitor, cardiac MRI (CMR) and CT coronary angiography.

Results:
A total of a 178 veteran athletes (m=128 f=50, mean age:54.8) and 123 controls (m=75 f=48, mean age 55.3) were recruited. Athletes demonstrated enlargement of all chamber sizes compared to sedentary controls on CMR. A significant proportion of male athletes (17.5%) exhibited myocardial fibrosis compared to none of the sedentary men (p=0.008) although this difference wasn’t observed in females (2.5% vs 0%, p=1.0). In 45% of cases fibrosis was subendocardial in distribution suggesting a prior ischaemic event. Male athletes with myocardial fibrosis had a 15% prevalence of ventricular tachycardia on a 24hour ECG compared to 1.06% of fibrosis free athletes (p=0.017). Compared to controls, male athletes had a higher prevalence of atherosclerosis (28.2% ≥2vessel disease vs 3.45%, p=0.009). Female athletes had similar indices of atherosclerosis compared to controls but they did demonstrate a U shaped relationship between V02 max and atherosclerosis: The lower and upper tertile of V02 Max had a higher prevalence of atherosclerosis (20%, and 26.7%) than those in the middle tertile(6.7%).

Conclusions:
Long term endurance exercise is associated with adverse cardiac remodelling. Myocardial fibrosis is common in male veteran athletes and is associated with ventricular tachycardia. Chronic endurance exercise also promotes atherosclerosis in males and females and this is likely to be dose dependent.