bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox-activated protein kinase A Type I (PKA RI) exerts a protective role during pathological pressure overload
Authors: Tarnowski D , Islam M.M.T , Trum M , Eaton P , Maier L.S , Wagner S , Sag C.M 
Published: November 2020

Abstract

Background
Phosphorylation of L-type calcium channels (LTCC) by cAMP-dependent protein kinase A (PKA) increases calcium current (ICa). However, it is unclear if PKA-dependent regulation of ICa is impaired in heart failure (HF) despite evidence for impaired β-adrenergic signaling. Recently, a novel PKA activation pathway by oxidation of regulatory subunit I (RI) has been identified.

Objective
We investigated the impact of redox-activated PKA for regulation of ICa, intracellular calcium (Ca) handling and contractile function in a pressure overload heart failure mouse model.

Methods
Knock-in mice (KI) that lack redox-dependent PKA activation (exchange of cysteine 17 of RI with serine) were compared to wild-type (WT) at baseline, 7 days and 6 weeks after transverse aortic constriction (TAC). Mouse echocardiography was performed to evaluate in-vivo cardiac function. ICa was measured by whole-cell patch clamp, PKA activity, cAMP levels, and protein levels of central Ca handling proteins were assessed at different time points in vitro.

Results
At baseline, no alterations of left ventricular (LV) function (echocardiography) were observed between WT and KI. TAC induced a significant RI oxidation in WT but not KI mice. Despite this difference, at 7 days after TAC, development of LV hypertrophy and impairment of systolic LV function in vivo were similar between WT and KI. Compared to baseline, 7 days after TAC a significant stimulation of peak ICa was observed in WT. In contrast to WT, the stimulation of peak ICa was absent in KI mice at 7 days after TAC. This impairment in peak ICa occurred despite a comparable increase in global PKA activity (ELISA), which was most likely due to increased cAMP levels in our TAC model (assessed by FLIM-FRET). Notably, cAMP levels were comparably increased in between groups (ELISA). Importantly, at 6 weeks after TAC, WT mice showed a mild additional deterioration of systolic LV function in vivo. In contrast, LV function was significantly more impaired in KI mice 6 weeks after TAC, which was accompanied by a significant increase in KI mice mortality. Comparing 6 weeks to 7 days after TAC, there was no stimulation of peak ICa in WT and even a significant decrease in peak ICa in KI mice. In accordance, PKA-dependent LTCC phosphorylation was absent in KI mice 6 weeks after TAC (western blotting).

Conclusion
Redox-activated PKA seems to exert a protective role by stimulation of ICa during pressure overload.

Funding Acknowledgement
Type of funding source: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft
Enhancing rare variant interpretation in inherited arrhythmias through quantitative analysis of 5182 cases from long QT syndrome and Brugada syndrome consortia cohorts and gnomAD population controls
Authors: Walsh R , Lahrouchi N , Glinge C , Krijger C , Skoric-Milosavljevic D , Whiffin N , Mazzarotto F , Ware J , Tadros R , Bezzina C 
Published: November 2020

Abstract

Background/Introduction
Guidelines for variant interpretation in Mendelian disease set stringent criteria to report a variant as (likely) pathogenic, prioritising control of false positive rate over test sensitivity and diagnostic yield, and require customisation for the specific genetic characteristics of gene-disease dyads. Inherited arrhythmias like long QT syndrome (LQTS) and Brugada syndrome (BrS) are genetically heterogeneous, with missense variants constituting the preponderance of disease-causing variants. Evidence from family segregation or functional assays to confirm pathogenicity are often unavailable or impractical in clinical genetic testing, leading to high rates of variants of uncertain significance and false negative test results.

Methods
We compared rare variant frequencies from 1847 LQTS (KCNQ1, KCNH2, SCN5A) and 3335 BrS (SCN5A) cases from the International LQTS/BrS Genetics Consortia to population-specific gnomAD data. We propose disease-specific criteria for ACMG/AMP evidence classes – rarity (PM2/BS1 rules) and enrichment of individual (PS4) and domain-specific (PM1) variants in cases over controls.

Results
Rare SCN5A variant prevalence differed between BrS cases with spontaneous (28.7%) versus induced (15.8%) type 1 Brugada ECG (p=1.3x10–13) and between European (20.8%) and Japanese (8.9%) patients (p=8.8x10–18). Transmembrane regions and specific N-terminus (KCNH2) and C-terminus (KCNQ1/KCNH2) domains were characterised by high enrichment of case variants and &gt;95% probability of pathogenicity. Applying the customised rules, 17.5% of European BrS cases and 73.7% of European LQTS cases had variants classified as (likely) pathogenic, compared to estimated diagnostic yields (case excess over gnomAD) of 19.3%/82.6%.

Conclusions
Large case/control datasets enable quantitative implementation of ACMG/AMP guidelines and increased sensitivity for inherited arrhythmia genetic testing.
Classification of Brugada/LQTS variants

Funding Acknowledgement
Type of funding source: Foundation. Main funding source(s): Dutch Heart Foundation, Netherlands Organisation for Scientific Research
Increase in inflammatory T cell subsets in atrial fibrillation: the missing link underlying inflammation in AF
Authors: Dumitriu I.E , Dimou P , Kaur S , Dinkla S , Kaski J.C , Camm A.J 
Published: November 2020

Abstract

Background
The precise role of inflammation in the development and perpetuation of atrial fibrillation (AF) is yet to be fully uncovered. T lymphocytes have pivotal roles in orchestrating inflammation. Specialised subsets of lymphocytes either promote or prevent inflammation. We are investigating a unique subset of lymphocytes, the CD4+CD28null T cells that expand in patients with chronic inflammation. These cells secrete high levels of pro-inflammatory cytokines and have cytolytic function. CD4+CD28null T cells are normally maintained under control by regulatory T cells (Treg), a specialised subset of T lymphocytes with suppressive function that maintain immune homeostasis and prevent pathogenic immune responses. The role of CD4+CD28null and Treg cells has not been investigated in AF.

Purpose
We hypothesised that in AF the balance between pro-inflammatory and regulatory T lymphocytes is skewed in favour of inflammatory T cells, which may sustain inflammation in AF.

Methods
Circulating CD4+CD28null T lymphocytes and Tregs were quantified by flow cytometry in paroxysmal and persistent AF patients and healthy controls (n=30). Inflammatory cytokines were quantified in serum and the function of T lymphocyte subsets was investigated using ex vivo functional assays.

Results
CD4+CD28null T lymphocytes were significantly increased in the circulation of AF patients compared to controls. Of note, a higher proportion of patients with persistent AF showed an increase in inflammatory CD4+CD28null T lymphocytes compared to patients with paroxysmal AF. A marked reduction in Treg cells was present in AF patients compared to controls. Functional assays showed that IL-7 and IL-15 cytokines were responsible for CD4+CD28null T lymphocyte expansion in AF patients.

Conclusions
We show that patients with AF have marked changes in T lymphocytes subsets: pro-inflammatory CD4+CD28null T cells increase significantly, whilst anti-inflammatory Tregs are significantly reduced. We show for the first time that the cytokines IL-7 and IL-15 are the main drivers of CD4+CD28null T cell expansion in AF patients. These novel findings may reveal novel therapeutic strategies (e.g. cytokine blockade) to re-establish the balance between pro- and anti-inflammatory mechanisms at work in AF to improve patient outcomes.

Funding Acknowledgement
Type of funding source: Foundation. Main funding source(s): British Heart Foundation
Fast delivery of flecainide via the pulmonary (bolus) or intravenous (rapid infusion) routes reduces atrial fibrillation conversion dose and minimizes negative inotropic burden
Authors: Belardinelli L , Nearing B.D , Verrier R.L 
Published: November 2020

Abstract

Background/Introduction
The negative inotropic effect of certain antiarrhythmic drugs limits their use for acute cardioversion of new-onset paroxysmal atrial fibrillation (AF).

Purpose
In an intact porcine model of AF, we examined the effects of pulmonary and intravenous (IV) administration of flecainide on left ventricular (LV) contractility, i.e., LV dP/dt max, at doses that are effective in converting AF to sinus rhythm. The magnitude of the decrease in LV dP/dt max and time that it remained below baseline, measured by the area under the curve (AUC), is referred to as negative inotropic burden.

Methods
Flecainide was delivered via intratracheal administration at 1.5 mg/kg bolus and compared to IV infusion at 1.0 mg/kg over 2 min (lower-dose, rapid) and 2.0 mg/kg over 10 min (ESC guideline) in 11 closed-chest, anesthetized Yorkshire pigs. These doses of flecainide have been shown effective in converting AF to sinus rhythm. Catheters were fluoroscopically positioned in the right atrium for pacing at 140 beats/min and in the LV to measure QRS complex duration and contractility (LV dP/dt). Intratracheal flecainide was delivered via a catheter positioned at the bifurcation of the main bronchi.

Results
The peak plasma levels (Cmax values) were similar but the AUC of plasma concentrations over time was greater for the higher-dose, slow IV infusion of flecainide than for either intratracheal instillation (by 32%) or lower-dose, rapid IV infusion (by 88%). Based on AUCs of LV dP/dt max (figure, left panel), the negative inotropic burden is 3.1- to 3.8-fold greater for the higher IV (1006% • min) than for the lower IV (323%·min) or the intratracheal doses (263% • min). There was a corresponding inverse increase in the AUC of QRS complex prolongation. The decrease in LV dP/dt max (Δ%) was correlated with the prolongation of the QRS complex (Δms) (y = −1.4337x + 3.6613, r2=0.69, p&lt;0.0001) (figure, right panel).

Conclusion
Rapid delivery of pulmonary or IV flecainide reduces the dose of drug required to achieve Cmax levels associated with conversion of AF. The attendant decrease across time in exposure of the ventricles to flecainide reduces QRS complex prolongation and the accompanying negative inotropic burden.

Funding Acknowledgement
Type of funding source: Private company. Main funding source(s): InCarda Therapeutics, Inc.
Epicardial adipose tissue CD4+ T cells as novel drivers in the development of atrial fibrillation
Authors: Vyas V , Wood L , Blythe H , Hunter R.J , Lall K.S , Finlay M.C , Longhi M.P 
Published: November 2020

Abstract

Background
Epicardial adipose tissue (EAT) is now a well-established independent risk factor for all forms of atrial fibrillation (AF). However, the cellular profile and immune mediators within EAT remain poorly defined.

Purpose
This study sought to define the immunological signature of EAT critical to its role in the development of both persistent AF and de novo post-operative AF (POAF).

Methods
Adult patients undergoing elective cardiac surgery with no prior AF history and those with pre-existing AF were recruited to undergo EAT sampling alongside subcutaneous adipose tissue (SAT) and pre-operative blood (adipose tissue and systemic controls respectively) sampling. The blood and tissue samples were immediately taken to the laboratory for immune cell isolation, flow cytometry and quantitative polymerase chain reaction (qPCR) analysis.

Results
A total of 71 patients were recruited including 9 patients with a prior history of AF. Of the 62 a priori sinus rhythm (SR) patients, 42 remained in SR post-operatively and 20 developed de novo POAF. No differences in absolute numbers of immune cells in the blood, EAT or SAT were detected on flow cytometry analysis between the three groups of patients. However, there was a significant increase (p&lt;0.01) in EAT-resident CD4+ memory T cell populations in pre-existing AF patients and a trend towards significance (p=0.09) in POAF patients. qPCR analysis of immune mediator expression in EAT demonstrated pre-existing AF patients uniquely showed a significant reduction (p&lt;0.005) in the pro-fibrotic mediator transforming growth factor-β (TGF-β) compared to the pre-existing AF patients (graph 1).

Conclusions and implications
Resident CD4+ memory T cell populations are locally and exclusively elevated in the EAT of pre-existing AF and POAF patients. This would suggest primed antigen-specific CD4+ T cells are present prior to the development of AF in patients who go on to develop de novo POAF. The reduced TGF-β levels observed in the EAT of AF patients indicates the EAT immune mediator profile differs to the underlying myocardial tissue, where increased TGF-β levels have previously been described in the persistent AF cohort. Therapies targeting this EAT-resident CD4+ T cell population would provide a novel approach to the management of the inflammatory components of AF genesis.
Graph 1

Funding Acknowledgement
Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Barts Charity, Abbott
Obesity associated pro-fibrotic protein augments fibrosis in heart
Authors: Tsukano Y , Shimizu I , Yoshida Y , Hsiao Y , Ikegami R , Hayashi Y , Suda M , Katsuumi G , Nakao M , Minamino T 
Published: November 2020

Abstract

Chronic sterile inflammation in visceral fat has causal roles for systemic metabolic disorders in obesity. Inflamed visceral adipose tissue secretes pro-inflammatory adipokines, and this contributes to tissue remodeling under a metabolically stressed condition. Various kinds of white adipokines are broadly studied, however, roles of brown adipose tissue (BAT) derived adipokines (BATokine) remain to be explored. In this project, we tried to characterize pathogenic role of BATokine in obesity related fibrotic disorders, especially focusing on heart failure with preserved ejection fraction (HFpEF). For this purpose, we analyzed two sets of DNA microarray data, and identified an obesity associated pro-fibrotic protein (OAFP) as a possible pathogenic BATokine. Our biobank studies showed OAFP increased in patients with diastolic dysfunction, and E/e' analyzed with cardiac echo increased in direct proportion to circulating OAFP level in humans. We generated dietary obese mice model, and found OAFP increased both in BAT and circulation. We generated a murine systemic or BAT specific OAFP knockout (KO) models, and found that obesity-induced diastolic dysfunction ameliorated in these models. Cardiac fibrosis was also suppressed by genetic depletion of OAFP. We found OAFP increased in circulation in aged humans and mice, and studies in chronologically aged mice showed this molecule increased in BAT with aging. Our results indicate that OAFP is secreted predominantly from BAT, and mediates pathogenic roles by augmenting cardiac fibrosis in dietary obesity or aging. Suppression of OAFP may become a therapy for HFpEF.

Funding Acknowledgement
Type of funding source: None
Macrophage-specific IRF5 deficiency stabilizes atherosclerotic plaques in ApoE−/− mice
Authors: Hilgendorf I , Haerdtner C , Leipner J , Dufner B , Hoppe N , Wolf D , Stachon P , Zirlik A , Bode C 
Published: November 2020

Abstract

Background
Interferon regulatory factor (IRF) 5 is a transcription factor promoting inflammatory macrophage polarization (M1 type). Given the central role of macrophages in atherosclerotic plaque development we hypothesized that macrophage specific deletion of IRF5 will protect from atherosclerosis.

Purpose
Investigate whether intrinsic blockade of M1 macrophage polarization ameliorates atherosclerosis

Methods
Female ApoE−/−LysMCre/wtIRF5flox/floxand ApoE−/−LysMwt/wtIRF5flox/floxmice were fed a high cholesterol diet for 3 months, and atherosclerotic plaque size and compositions as well as inflammatory gene expression were analyzed. Mechanistically, IRF5-dependend bone marrow derived macrophage cytokine profiles were tested under M1 and M2 polarizing conditions. Aortic macrophage chimerism in irradiated ApoE−/− mice reconstituted with a mixture of CD45.1+ ApoE−/− (WT) and CD45.2+ ApoE−/− LysMCre/WtIRF5flox/flox(KO) bone marrow was evaluated to distinguish systemic from intra-plaque effects on monocyte/macrophage kinetics.

Results
Macrophage-specific IRF5 deficiency blunted LPS/IFNg-induced IL-1β and TNFα gene expression in vitro. In ApoE−/− mice, macrophage-specific IRF5 deficiency did not alter lesion size in the aortic root but significantly reduced macrophage and lipid contents by about 25% while increasing collagen deposition by over 30%. This was accompanied by relative reductions in gene expressions of pro-inflammatory (IL-1β, IL-6, IL-12) and increases in anti-inflammatory (Mertk, TGFβ, CD206) markers in atherosclerotic aortas of ApoE−/−LysMCre/wtIRF5flox/floxmice. When competing with IRF5 deficient cells in mixed irradiation bone marrow chimeras, IRF5 competent macrophages showed an advantage in accumulating in atherosclerotic aortas as disease progressed independent of monocyte recruitment.

Conclusion
Transcription factor IRF5 promotes a pro-inflammatory response in macrophages leading to vulnerable plaque formation and plaque destabilization, providing genetic evidence for targeting macrophage polarization in atherosclerosis.

Funding Acknowledgement
Type of funding source: Public grant(s) – National budget only. Main funding source(s): DFG
Long non-coding RNA TERRA influences DNA damage and survival of endothelial cells and cardiomyocytes
Authors: Bink D , Pham T.P , Hofmann P , Dimmeler S , Boon R.A 
Published: November 2020

Abstract

Ageing is the major risk factor for cardiovascular disease. Current therapies are mainly based on proteins, while targeting long non-coding RNAs (lncRNAs) is largely unexplored. Long non-coding RNAs are emerging as novel regulators of cellular functions and contributors to cardiovascular ageing. Although telomeres are heterochromatic regions, non-coding transcripts called Telomeric repeat-containing RNA (TERRA) are transcribed from the telomeres of most chromosomes. The transcription of TERRA starts at the subtelomere and ends in the telomere, leading to molecules of 0.2–10kb. This study aims to characterize the role of TERRA in the cardiovascular system.
TERRA molecules from different chromosomes were upregulated in the hearts of old mice compared to young mice (p=0.002). An increased TERRA expression was also shown in heart tissue of patients with ischemic heart disease compared to donor heart tissue (p=0.001). In vitro an upregulation of the TERRA molecule transcribed from chromosome 20 (h20q-TERRA) was found in old passage human umbilical vein endothelial cells (HUVECs) (P15–17) compared to young HUVECs (P3) (p=0.014). IPSC-derived cardiomyocytes also increased the expression of h20q-TERRA with increasing passage (p=0.011). After knockdown of h20q-TERRA with LNA GapmeRs HUVECs show less sprout formation in a spheroid assay compared to negative control transfected HUVECs (p=0.002), without showing a change in migration (p=0.205) or proliferation (p=0.114). H20q-TERRA knockdown revealed that there was more apoptosis (p=0.015), more DNA damage as measured with the comet assay (p&lt;0.001), increased γH2AX levels (p=0.029) and an increase in γH2AX colocalization with the telomere (p=0.011). The amount of phosphorylated P53 was also increased after knockdown (p=0.038), while it was decreased after TERRA overexpression (p=0.001). Inhibition of the ATM-yH2AX-P53 pathway did however not reduce the increased apoptosis after knockdown (KU60019 p=0.399; siP53 p=0.303). Silencing the m18-TERRA molecule in mouse endothelial H5V cells led to an increase in caspase activity (p=0.004) similar to what was shown in HUVECs. In addition, increased caspase activity (p=0.012), increased γH2AX levels (p&lt;0.001) and increased γH2AX colocalization with the telomere (p=0.007) was also shown after silencing of h20q-TERRA in human cardiomyocytes.
In summary, our data demonstrates that TERRA is upregulated with ageing and plays a role in endothelial and cardiomyocyte function and survival. These data show that TERRA transcripts are induced in cardiovascular ageing and are essential for endothelial cell function.

Funding Acknowledgement
Type of funding source: Public grant(s) – EU funding. Main funding source(s): Horizon 2020
Coronary microvascular dysfunction results in impaired coronary flow reserve and altered oxygen balance in a swine model of INOCA with multiple risk factors
Authors: Sorop O , Van De Wouw J , Van Drie R.W.A , Joles J.A , Verhaar M.C , Merkus D , Duncker D.J 
Published: November 2020

Abstract

Introduction
Comorbidities of ischemic heart disease, including diabetes mellitus (DM), hypercholesterolemia and chronic kidney disease (CKD), are associated with coronary microvascular dysfunction (CMD) and may contribute to myocardial “Ischemia and No Obstructive Coronary Artery disease” (INOCA).

Purpose
We studied myocardial perfusion and oxygen delivery using a novel swine model with multiple comorbidities.

Methods
DM (streptozotocin), HFD (high fat diet) and CKD (renal embolization), were induced in 12 female swine (DM+HFD+CKD), while 12 healthy female swine on a normal diet served as controls (CON). After 6 months, in the absence of coronary atherosclerosis, myocardial perfusion and function were studied at rest and during treadmill exercise. Results DM+HFD+CKD animals showed hyperglycemia, hypercholesterolemia and impaired kidney function. During exercise, DM+HFD+CKD demonstrated impaired myocardial blood flow and oxygen delivery, necessitating higher myocardial oxygen extraction (despite reduced capillary density), resulting in lower coronary venous oxygen levels, (Fig. 1). These perturbations were associated with lower myocardial efficiency, requiring higher oxygen consumption for a given level of myocardial work (Fig. 1), lower myocardial lactate consumption, stroke volume and LVdP/dtmax, suggestive of myocardial ischemia and dysfunction. Furthermore DM+HFD+CKD showed a reduction in adenosine-recruitable coronary flow reserve (2.69±0.26 vs 3.64±0.2 in CON, p&lt;0.05), which was exclusively the result of an increase in basal coronary blood flow, while maximal coronary flow per gram of myocardium was maintained. The latter was consistent with the unchanged arteriolar wall/lumen ratio, arteriolar density and peri-arteriolar collagen content. eNOS blockade indicated loss of NO bioavailability in DM+HFD+CKD swine in vivo (Fig. 1), which was supported by blunted endothelium-dependent vasodilation to bradykinin in isolated small arteries. These findings suggest that changes in coronary microvascular function rather than structure contributed to the perturbations in myocardial oxygen delivery.

Conclusion
Common comorbidities result in CMD and impaired NO bioavailability rather than structural alterations in the microvasculature in swine, in the absence of appreciable atherosclerosis. These alterations are severe enough to produce perturbations in myocardial oxygen balance and coronary metabolism and function, particularly during exercise, resembling key features of INOCA.
Figure 1

Funding Acknowledgement
Type of funding source: Public grant(s) – EU funding. Main funding source(s): This study was supported by grants from the European Commission FP7-Health-2010 grant MEDIA-261409, the Netherlands CardioVascular Research Initiative: an initiative with support of the Dutch Heart Foundation [CVON2014-11 (RECONNECT)].