bluuebunny/crossref_metadata_2025 huggingface dataset:
Fibroblast-specific SOCS3 deficient mice exhibits decreased myocardial fibrosis and increased cardiomyocyte survival after acute myocardial infarction
Authors: Okabe K , Yasukawa H , Sasaki T , Takahashi J , Nohara S , Shibata T , Yanai T , Akagaki D , Shibao K , Yamamoto M , Shima K , Fukumoto Y
Published: November 2023

Background

Left ventricular (LV) remodeling after acute myocardial infarction (AMI) results in poor cardiac performance leading to heart failure. LV remodeling after AMI is characterized by infarct expansion, LV dilation, and fibrosis of viable myocardium. Suppressor of cytokine signaling-3 (SOCS3) is an endogenous negative-feedback regulator of the STAT3 signaling pathway. We previously reported that myocardial SOCS3 plays a detrimental role in LV remodeling after AMI; however, the role of STAT3 and SOCS3 within fibroblast in LV remodeling after AMI remains elusive.

Objective

The aim of this study is to clarify the role of STAT3 and SOCS3 within fibroblasts in LV remodeling during AMI in mice.

Methods

To investigate the role of STAT3 signaling and SOCS3 within fibroblast, we generated tamoxifen-induced fibroblast-specific SOCS3-deficient (fib-SOCS3 KO) mice. AMI was induced by permanent ligation of the left anterior descending artery in mice. After 2 weeks of induction with tamoxifen, histological evaluation by Hematoxylin Eosin staining and Picro-Sirius Red staining, cardiac function evaluation by echocardiography using a Vevo 3100 Echo Imaging System (Visual Sonics), and protein expression using Western blot analysis were performed.

Results

There was no significant difference in 2-week survival rate between fib-SOCS3 KO group and wild type (WT). Two weeks after AMI, ventricular weight was less in fib-SOCS3 KO mice compared to WT mice (p<0.05). In terms of cardiac function, LV ejection fraction was predominantly increased in fib-SOCS3 KO mice compared with WT mice, as measured by the Area method (p<0.05). There was no difference in LV end-diastolic area, but LV end-systolic area was significantly less in fib-SOCS3 KO mice than in WT mice. Histologically, residual viable myocardium in the infarcted area was greater in fib-SOCS3 KO mice compared with WT mice. The percentage of fibrotic area in the LV short-axis plane was significantly less in fib-SOCS3 KO mice than in WT mice. Western blot analysis revealed that phosphorylated-STAT3 tended to be elevated in fib-SOCS3 KO mice than in WT mice.

Conclusions

Our data suggest that STAT3 and SOCS3 within fibroblast may play an important role in the prevention of LV remodeling after AMI.
Role of long non-coding RNA Zeb2os in protection of the injured heart
Authors: Caliandro R , Boender A , Van Rooij E , Boink G J J , Giacca M , Christoffels V M , Gladka M M
Published: November 2023

Heart failure due to ischemic heart disease is one of the leading causes of death worldwide. Terminated vasculature and cardiomyocyte apoptosis due to myocardial infarction are critical events in infarct healing. Therefore, identifying factors that can enhance cardiac repair by restoring the capillary network and inhibiting cardiomyocyte death is of great significance. Accumulating evidence implies that long non-coding RNAs (lncRNAs) are potent regulators of cardiac development and disease.

Our preliminary data show the potential cardioprotective function of the long non-coding RNA Zeb2 opposite strand (Zeb2os). This lncRNA overlaps and is antisense to ZEB2 at the 5' splice site of an intron within the 5' UTR. Zeb2os was shown to prevent splicing of the intron containing an internal ribosome entry site (IRES) that increases translation of the ZEB2 transcript. In line with the known function of ZEB2, Zeb2os has pro-angiogenic and anti-apoptotic functions in different organs. However, its role in the heart still has to be determined.

Our results show that Zeb2os expression is decreased in cultured cardiomyocytes subjected to H2O2-mediated oxidative stress, which correlates with increased apoptosis and reduced antioxidant defence of cardiac muscle cells. AAV6-mediated overexpression of Zeb2os in hiPSC-derived cardiomyocytes protects from H2O2-induced apoptosis, suggesting it may have cardioprotective activity, possibly through regulating Zeb2 translation. Additionally, systemic AAV9-mediated delivery of Zeb2os to the mouse heart enhanced angiogenesis by increasing the number of proliferating endothelial cells. Moreover, RNA-sequencing of Zeb2os overexpressing hearts at baseline implicated Zeb2os in the regulation of numerous genes related to response to hypoxia.

In conclusion, we uncovered/identified Zeb2os as a new potential cardioprotective factor with pro-angiogenic and anti-apoptotic properties. We are currently investigating the effect of AAV9-mediated delivery of Zeb2os in a mouse model of cardiac ischemia to understand further its protective role in the injured heart, which is an essential step towards the development of improved therapies for ischemic heart disease.
The mesencephalic astrocyte-derived neurotrophic factor (MANF) as a novel regulator of post-infarction cardiac sympathetic hyperinnervation
Authors: Blok M , Van Gils J M , Boukens B J D , Kielbasa S M , Van Schendel B W , Schoones J W , Smits A M , Goumans M J T H , De Ruiter M C , Jongbloed M R M
Published: November 2023

Background

Excessive outgrowth of sympathetic nerve fibers (sympathetic hyperinnervation) around the infarcted myocardium is associated with ventricular arrhythmia and an increased risk of sudden cardiac death. Post-infarction, epicardial cells exit quiescence through epithelial-to-mesenchymal transition (EMT), resulting in the formation of epicardium-derived cells (EPDCs). EPDCs support cardiac repair through differentiation into various cardiac cell lineages, as well as secretion of paracrine factors that stimulate processes such as angiogenesis. Recently, we demonstrated that human EPDCs reinforce neurite outgrowth in vitro. Whether EPDCs regulate cardiac innervation through paracrine signaling and contribute to post-infarction sympathetic hyperinnervation is unknown.

Purpose

To identify epicardial paracrine factors post-infarction that are involved in nerve growth.

Methods

Single-cell RNA-sequencing (scRNA-seq) datasets capturing epicardial cells of the healthy and infarcted adult mouse heart were collected from published research articles and were integrated into one object using Seurat. A list of gene products of known involvement in biological processes related to nerve growth (675 unique entries in total) was compiled. Based on this list, differential gene expression analysis on data from the integrated scRNA-seq object was performed to uncover highly-expressed candidates in the epicardial cell population. Epicardial expression of a candidate paracrine factor was validated by immunohistochemistry in the infarcted mouse heart as well as in an adult human in vitro model of EPDC EMT by immunocytochemistry and transcriptomic analysis.

Results

In our integrated scRNA-seq object, we identified high expression of Manf in epicardial cells post-infarction. Consistent with this finding, immunohistochemistry showed that Manf was up-regulated in the infarcted area, borderzone area, and epicardial region situated close to the infarct, an area where also hyperinnervation is observed. In vitro, MANF transcript expression was significantly down-regulated (p<0.01) in human EPDCs that were stimulated with TGFβ3 to induce EMT compared to EPDCs in which EMT was inhibited. In line with this, immunocytochemistry staining of MANF indicated that MANF expression was down-regulated in human EPDCs stimulated with TGFβ3.

Conclusion(s)

This study is the first to show that Manf is highly expressed in the epicardial region close to the infarct. In vitro, MANF is down-regulated in human adult EPDCs post-EMT. Future experiments will be directed toward determining the effect of MANF knockdown in human EPDC on neurite outgrowth in co-cultured human sympathetic neurons.MANF expression in human EPDCs after EMTManf expression after infarction
Fully automatic screening for atrial fibrillation using a photoplethysmography based wristband and a novel smart infrastructure
Authors: Abdelhamid K , Reissenberger P , Piper D , Koenig N , Hoelz B , Schlaepfer J , Gysler S , Mccullough H , Ramin-Wright S , Gabathuler A , Khandpur J , Meier M , Eckestein J
Published: November 2023

Background

Atrial Fibrillation (AF) is the leading cause of stroke, and its prevalence is expected to rise. While early detection is crucial in preventing thromboembolic events, its often asymptomatic and paroxysmal nature makes it challenging to capture using conventional electrocardiography (ECG). Photoplethysmography (PPG) enabled devices, such as smartwatches, allow continuous monitoring of the heart rhythm and accurate screening for AF.

Purpose

In this study, we aimed to build an IT-infrastructure for fully automated screening of AF in hospitalised patients at risk using a PPG-based wrist worn wearable device.

Methods

We conducted an investigator-initiated, prospective, clinical trial to evaluate the performance of a PPG-based wristband coupled to an automatic data process device hub in hospitalised patients. Participants with a CHA2DS2-VASc score of two or higher and no prior history of AF were eligible for the study. Consenting participants received a wristband with a built-in PPG sensor to be worn during the entire hospital stay. Data from the wristband was automatically transmitted, stored, analysed and visualised. When absolute arrhythmia (AA) was detected in the PPG signal, a subsequent seven-day Holter ECG was performed to confirm the diagnosis.

Results

A total of 346 patients were included in the analysis (age 72 ± 10 years; 175 females (50.6%); mean CHA2DS2-VASc score of 3.5 ± 1.3). No data was lost in the process. The mean monitoring time was 4.3 ± 4.4 days, 45.9% was evaluable. In twelve patients (3.5%, CI: 1.5% - 5.4%) absolute arrhythmia (AA) was detected in the PPG-signal. The mean screening time until first detection of AA was 14.7 ± 16.8 hours. The highest detection rate was observed within the first 24 hours of screening (p = 0.004) (Figure 1). The AA burden per hour was 1.9 times greater during the night (22:00 - 06:00) compared to the day (p = 0.003) (Figure 2). Of the 346 patients, 304 (87.9%) were compliant in wearing the wristband for the entire hospitalisation. In nine patients a Holter ECG was recorded, no AF was identified.

Conclusions

We successfully established an infrastructure for automated AF screening in hospitalised patients using wrist-worn PPG devices, enabling real-time visualisation of incoming data and facilitating therapeutic interventions with minimal delay. To our knowledge this is the first hospital to implement a fully automated AF screening infrastructure based on PPG devices. In a population at risk, AA was identified in 3.5% of all patients. The high compliance rate of the wearable device further supports its feasibility and utility in clinical practice.Figure 1:Time to first detection of AAFigure 2:Total AA burden per hour
From cells to circulating biomarker: BMP10 is a myocyte-secreted peptide with potential to detect atrial fibrillation
Authors: E Molina C , Sommerfeld L , Zeller T , Obergassel J , Wieboldt H , Conradi L , Reichenspurner H , Nikolaev V O , Kirchhof P , Fabritz L
Published: November 2023

Background

Early onset detection and recurrence prediction of atrial fibrillation (AF) may improve therapeutic decision-making, prognosis and long-term outcome. Plasma proteome analyses and mechanistic studies identified bone morphogenetic protein 10 (BMP10) as an atrial-specific secreted biomolecule for AF associated with reduced paired-like homeodomain transcription factor 2 (PITX2) expression.

Purpose

Our aim is 1) to confirm BMP10 synthesis and secretion by human atrial isolated myocytes, 2) to compare BMP10 secreted levels between right atrial, left atrial and left ventricular myocytes, and 3) to assess if BMP10 secretion is indeed associated with AF in human myocytes.

Methods

Right atrial (RA), left atrial (LA) and left ventricular (LV) myocytes were isolated from 16 tissues samples of patients undergoing open heart surgery which were currently in sinus rhythm (SR) or AF. Freshly isolated myocytes were resuspended in minimal essential medium (MEM, M1) containing fetal bovine serum (FBS) and plated in laminin coated dishes. M1 was collected after 3 hours of culture and substituted by FBS-free medium (M2), which was collected after 48 hours of culture. Cardiomyocyte-released BMP10 levels were measured in M1 and M2 by ELISA.

Results

Cardiomyocytes from twelve patients (68±2.7 years, 52±2.1 % ejection fraction, 17 % women, 50 % with AF, 50 % valvular surgery and 75 % bypass) were cultured and BMP10 secreted levels analyzed. BMP10 concentrations were high in medium from atrial cardiomyocytes (2.76±1.8 ng/µl) and negligible in medium from ventricular cardiomyocytes (0.01±0.005 ng/µl). Left atrial cardiomyocytes released less BMP10 than right atrial cardiomyocytes (LA 0.02±0.007 ng/µl; RA 3.50±2.3 ng/µl). In addition, BMP10 concentrations were higher in right atrial cardiomyocytes from patients with AF (3.76±3.6 ng/µl) than in the right atrial cardiomyocytes from patients in SR (0.97±0.9 ng/µl).

Conclusion

Our results provide a direct proof that BMP10 is secreted by human atrial myocytes, mainly right atrial myocytes. Furthermore, atrial myocytes from patients with AF secreted significantly more BMP10 than myocytes from patients in sinus rhythm. These observations validate the atrial cardiomyocyte origin of circulating BMP10, making BMP10 a potentially attractive atrial-specific cardiac biomarker.
Regulatory roles of the N6-methyladenosine demethylase FTO in cardiac remodeling
Authors: Annamalai K , Buchholz E , Castro R , Panyam N , Fischer A , Toischer K
Published: November 2023

Background

The most prevalent internal RNA modification, N6-methyladenosine (m6A), serves as an additional layer of transcriptional and translational regulation. Methyl transferases (like METTL3) and demethylases (e.g., FTO) are the enzymes that catalyze m6A methylations. Our result showed that loss of FTO causes maladaptive cardiac remodeling in rodent hearts, which is consistent with other studies that emphasized the importance of FTO-dependent m6A RNA methylation in maintaining cardiac homeostasis, ventricular hypertrophy, and heart failure. Despite the fact that FTO is essential for stress-induced cardiac hypertrophy, its underlying functional mechanisms in regulating maladaptive cardiac remodeling are not yet known.

Purpose

In this study, we showed the necessity of FTO dependent m6A methylation in coordinating the molecular and signaling events that are engaged in cardiac hypertrophy, and further identified the detrimental signaling mechanisms that are regulated by FTO during pathological remodeling.

Methods

Firstly, the control and FTO-cKO (cardiomyocyte specific FTO knockout) group mice were subjected to sham and TAC (transverse aortic constriction) operation. Echocardiography was performed 1 week post-TAC. Secondly, m6A RNA immunoprecipitation (meRIP) sequencing were performed from the isolated mice heart tissue. Additionally, the effect of apoptosis and mTORC1 upon FTO depletion were analysed in both rodents and iPS-CMs. In vitro the interrelation between FTO demethylase, mTORC1 and autophagy in the regulation of cardiac apoptosis were identified by 1. inhibiting mTORC1 pathway with specific inhibitors, and by 2. inhibiting 'late autophagy' in FTO silenced iPS-CMs.

Results

In contrast to control mice, which exhibit concentric hypertrophy at the beginning of induced pressure overload (PO), echo analysis of one week post-TAC revealed that FTOcKO mice develop a DCM-like phenotype. Further, MeRIP-seq data showed that there is deregulation in the m6A methylation with FTO depletion. Around 114 differently hypermethylated transcripts and 58 differentially hypomethylated transcripts were discovered in FTOcKO sham as compared to Control sham; these transcripts are involved in the control of apoptosis, the mTORC1 signaling pathway, lysosomal biogenesis, and autophagy. In both rodents and iPS-CMs, FTO ablation dramatically enhances cardiac apoptosis and the mTORC1 signaling pathway. Furthermore, inhibition of mTORC1 pathway attenuates cardiac apoptosis in siFTO-iPS-CMs. Moreover, autophagic flux analysis revealed that FTO depletion cause autophagic flux impairment and exacerbate cardiac apoptosis. However, the autophagic flux is ameliorated with mTORC1 inhibition in late-autophagy inhibited siFTO-iPS-CMs.

Conclusion

Our data unravel the novel roles of FTO demethylase in the course of cardiac remodeling, which opens doors to therapeutic interventions in the treatment of cardiac hypertrophy and heart failure.
Melanocortin 1 receptor deficiency protects against pathological cardiac hypertrophy
Authors: Suominen A , Ruohonen S , Szabo Z , Savontaus E , Kerkela R , Rinne P
Published: November 2023

Background

The melanocortin system, including adrenocorticotropic hormone, melanocyte-stimulating hormones and five melanocortin receptors (MC-R), regulates important physiological functions such as pigmentation and energy homeostasis. It has been also recently implicated in the regulation of pathological cardiac remodeling but the role of different MC-R subtypes in the heart remain unknown.

Purpose

Based on the abundant cardiac expression of MC1-R, we hypothesized that it is functionally active in the heart and regulates pathological cardiac remodeling.

Methods

Rat H9c2 cells were used to study the effects of the selective MC1-R agonist LD211 on intracellular signaling cascades, gene expression and cellular growth response by using Western blotting, quantitative RT-PCR and 3H-leucine incorporation assay, respectively. Recessive yellow mice (Mc1re/e) were used as a model of global MC1-R deficiency. Inducible cardiomyocyte-specific MC1-R knockout mouse model (Mc1r-cKO) was engineered by intercrossing MC1-R floxed mice (Mc1rfl/fl) with tamoxifen-inducible Myh6-MerCreMer transgenic mice (Myh6-MCM). Mc1re/e and Mc1r-cKO mice were subjected to transverse aortic constriction (TAC, 8 wks) or subcutaneous infusion of angiotensin II (Ang II, 4 wks) to induce pathological cardiac hypertrophy. Cardiac structure and function were measured by echocardiography and by histological examination of H&E-stained heart sections.

Results

Treatment of H9c2 cells with LD211 increased MAP-kinase p-38 phosphorylation (+53 %, P=0.005 vs control), upregulated the expression of B-type natriuretic peptide (Nppb, +40 %, P=0.03 vs control) and increased 3H-leucine incorporation (+27 %, P=0.006 vs control). Mc1re/e mice showed reduction in ventricular weight (-29 mg, P=0.03) compared to WT mice after TAC operation, and reduced left ventricular (LV) expression of atrial natriuretic peptide (Nppa) and fibrosis-related genes (Ctgf and Mmp2). In terms of LV systolic performance, TAC-operated Mc1re/e mice showed tendency towards improved LV ejection fraction (EF, +6 %, P=0.06) compared to WT mice. To further investigate whether the phenotype of Mc1re/e mice is driven by deficient MC1-R signaling in cardiomyocytes, we characterized Mc1r-cKO mice, which recapitulated the phenotypic features of Mc1re/e mice. Specifically, TAC-operated Mc1r-cKO mice displayed reduced ventricular weight (-38 mg, P=0.007) and downregulation of LV expression of Nppa and fibrosis-related genes compared to Myh6-MCM mice. Likewise, in a model of Ang II-induced cardiac hypertrophy, Mc1r-cKO mice showed reduced ventricular weight (-10 mg, P=0.015) compared to Myh6-MCM mice, indicating that the protection against pathological cardiac hypertrophy was model-independent.

Conclusion

Our studies demonstrate that MC1-R activation promotes cardiomyocyte growth in vitro, while global and cardiomyocyte-specific MC1-R deficiency protects against pathological cardiac hypertrophy induced by TAC or Ang II infusion.
Thrombosis in the coronary microvasculature may be responsible for impaired cardiac relaxation and diastolic dysfunction
Authors: Rouault P , Guimbal S , Cornuault L , Foussard N , Bourguignon C , Grouthier V , Choveau F , Benoist D , Gadeau A P , Couffinhal T , Renault M A
Published: November 2023

Introduction

Heart Failure with Preserved Ejection Fraction (HFpEF) is proposed to be caused by endothelial dysfunction in cardiac small vessels. We previously identified Hhipl1,as a gene upregulated in the coronary vasculature of Leptin receptor deficient mice (Leprdb/db) a well-established mouse model of HFpEF. Importantly, Hhipl1 encodes for a decoy receptor of Desert Hedgehog (DHH) which is known to be critical for endothelial integrity.

Objective

Our objective is to investigate the functional consequences of impaired Hedgehog (HH) signaling in the adult heart in order to identify novel mechanisms underlying the development of diastolic dysfunction.

Method

To do so, Cdh5-Cre/ERT2, DhhFlox/Flox (DhhECKO) mice and their control littermates were administered with tamoxifen at 8 weeks of age to induce Dhh KO. Their cardiac function, exercise tolerance, and the phenotype of their coronary vasculature were assessed one month later.

Results

DhhECKO mice presented significantly reduced exercise tolerance, increased end diastolic pressure (EDP) and Tau, with no change in their ejection fraction consistent with diastolic dysfunction. At molecular and cellular level, impaired cardiac relaxation in DhhECKO mice was associated with a significantly decreased phospholamban phosphorylation on Thr17 and an alteration of sarcomeric shortening in ex-vivo. Besides, as expected, DhhECKO mice exhibited phenotypic changes in their coronary vasculature including a prominent pro-thrombotic phenotype (63±6,2 vs 25±5,2 thrombi/mm²; p<0,001) leading to an impaired capillary perfusion and local hypoxia. Notably, antiaggregant therapies (aspirin and clopidogrel) prevented the occurrence of both diastolic dysfunction and exercise intolerance in DhhECKO mice demonstrating for the first time that thrombosis may promote diastolic dysfunction. Importantly, we confirmed the critical role of thrombosis in Leprdb/db mice which also displayed increased cardiac small vessel thrombosis in comparison to control mice. Alike DhhECKO mice, we found that antiaggregants decreased EDP (6,3±0,4 mmHg in aspirin-treated vs 11,3 ± 0,79 in control mice; p=0,001) and improved exercise tolerance in Leprdb/db mice (34 ± 2,52 min in aspirin-treated vs 24 ± 3,55 in control mice; p=0,004).

Conclusion

Altogether, these results demonstrate that small vessel thrombosis may participate in the pathophysiology of heart failure with preserved ejection fraction.
A novel technology for heart failure that utilizes the respiratory effort to shift fluids from the lung and alleviate cardiac workloads; feasibility study in sheep
Authors: Landesberg A , Livneh A , Shofti R , Amir O
Published: November 2023

Introduction

Hemodynamic congestion is governed by inflow from RV and drainage through LV. However, ventricle functions are affected by the intrathoracic/pleural pressure: Negative pleural pressure (PPL) increases RV outflow while decreasing LV outflow, and vice versa at high PPL. Cardiac decompensation is associated with an increase in the respiratory effort (the peak-to-peak changes in PPL). We suggest to utilize this respiratory effort to shift fluid out of the lung and alleviate hemodynamic congestion. It is done by pacing the heart when PPL is high and the LV stroke volume is larger than the RV stroke volume.

Purpose

To test the feasibility of the novel technology in sheep. To verify that it is possible to modify the distribution of the heart beat within the respiratory cycle (slightly modify the rhythm according to the PPL) with insignificant effect on mean heart rate.

Methods

The utility was validated in sheep (N=9), under spontaneous breathing before and after induction of acute infarction by balloon inflation in the mid-LAD artery. The device senses the intracardiac electrical activity and respiratory effort and paces the right atrium when the PPL is high. The R-R interval of the paced beats was shorter than the sinus R-R interval by less than 10%. The effects of PPL and device pacing on LV and RV stroke-volumes were derived from simultaneous measurements of RV and LV pressure-volume loops, utilizing two impedance catheters (CD-Leycom) within both ventricles.

Results

The respiratory effort had significant effects on RV and LV outputs before and after infarction. The stroke volumes of the two ventricles were in antiphase! At low PPL the RV output increased while the LV decreased by about 10%, and the opposite occurred at high PPL. The pacing increased cardiac beating probability at high PPL. Sequential pacing for one minute increased the systolic pressure by 5 mmHg while decreasing the pulmonary artery pressure. Based on the pressure-volume loops, each paced breath cycle increased the LV outflow by 1.14 ml and decreased RV outflow by 0.36ml, yielding a shift of 1.5 ml from the lung. Interestingly, it was associated with a decrease in the sinus rate, which further decreased cardiac beating at low PPL and may represent a decrease in sympathetic tone.

Conclusions

Pacing only 1% of the ∼20,000 daily breath-cycles can shift 300 ml from the lung per day! The technology is agnostic of the heart-failure etiology. Preclinical studies in a model of chronic heart failure are required to further validate the novel approach.
Impaired cardiac BCAA catabolism associated with impaired myocardial efficiency during exercise in a porcine model with multiple risk factors
Authors: Zandbergen L , Van Dijk C G M , Sen P , Sorop O , Van Drie R W A , Shashikadze B , Frohlich T , Verhaar M C , Cheng C , Duncker D J , Merkus D
Published: November 2023

Background

Diabetes mellitus (DM), chronic kidney disease (CKD) and consumption of a high-fat diet (HFD), are well known risk factors for diastolic heart failure. We recently developed a multiple comorbidity swine model (MCS), with DM (streptozotocin), HFD and CKD (kidney embolization), and showed that 6 months of sustained hyperglycemia, hypercholesterolemia and kidney dysfunction resulted in inflammation and oxidative stress associated with coronary microvascular dysfunction and left ventricular diastolic dysfunction. Additionally, MCS animals showed impaired myocardial efficiency during exercise as demonstrated by increased myocardial oxygen consumption (Fig. A), suggesting an impairment in myocardial mitochondrial function.

Purpose

Here we used a combined omics (single nuclei RNA sequencing and proteomics) approach to study the molecular pathways involved in mitochondrial dysfunction.

Methods

15 MCS and 10 healthy control female swine were included in the study. Proteome analysis and single nuclei RNA sequencing, was performed on frozen left ventricle myocardial samples.

Results

Proteome analysis of MCS hearts showed reduced expression of branched-chain amino acid (BCAA) catabolism proteins (Fig. B), most notably BCAT2, MCCC1 and MCCC2. Single nuclei RNA sequencing of a subgroup of the same animals demonstrated a downregulation of these genes specifically in cardiomyocyte subpopulations. Besides being a source of ATP, via oxidative phosphorylation in mitochondria, BCAAs, encompassing essential amino acids (leucine, valine and isoleucine), act as signaling molecules. Thus, increased BCAA levels reduce insulin sensitivity, modulate mitochondrial substrate utilization and impair mitochondrial function, resulting in increased mitochondrial production of reactive oxygen species (ROS). These findings are consistent with our data in the MCS swine indicating that impaired BCAA metabolism was found in the myocardium of animals with comorbidities and were associated with increased ROS levels (8-isoprostane 12.9±0.8 pg/mg protein in MCS vs 10.3±0.5 in healthy animals, P=0.02 by T-test) and impaired myocardial efficiency during exercise (Fig. A).

Conclusion

Taken together, these findings suggest an essential role of altered BCAA cardiomyocyte metabolism resulting in mitochondrial dysfunction, increased oxidative stress and subsequent alterations in the myocardial function.Fig.
Assessment of global and segmental strain in heterozygous APE1/Ref-1 transgenic mice using cardiac magnetic resonance imaging
Authors: An S Y , Kim S M , Lee E O , Jeon B H
Published: November 2023

Background

Apurinic/apyrimidinic-endonuclease1(APE1/Ref-1) is a redox factor necessary for DNA binding and transcription regulator in ROS generation. The association between APE1/Ref-1 and heart failure(HF) has been observed in previous studies. Heterozygous APE1/Ref-1 transgenic mice displayed endothelial cell dysfunction with systemic hypertension. Global strain(GS) measures the myocardium's deformation along its axis and is known to be a sensitive marker of subclinical HF in hypertensive patients with preserved ejection fraction.

Purpose

This study aims to investigate the functional dynamics and GS of the heart in heterozygous APE1/Ref-1 mice to help identify the association between APE1/Ref-1 and early signs of HF and translate to clinical applications.

Methods

A study was conducted to assess the functional parameters of both the left ventricle(LV) and right ventricle (RV) and perform LV global and segmental strain analysis using cardiac magnetic resonance imaging(CMR) in heterozygous APE1/Ref-1 transgenic mice(n=4) and wild type mice (n=4) of age 10-12 weeks. A 7T CMR scanner and FSE T1 sequence were used to acquire short-axis views of mouse cardiac images. LV and RV functional parameters including ejection fraction(EF), stroke volume(SV), cardiac output, peak filling rate, peak emptying rate and strain indices including global circumferential strain, global radial strain, segmental circumferential strain, and segmental radial strain were calculated with a software dedicated to analyzing CMR images. Global LV and RV function was quantified both manually and using an AI-based algorithm of LV and RV segmentation. The strain analysis was performed using the strain medical image tracking toolbox module. Additionally, reproducibility testing was done to validate the accuracy of AI-driven calculations.

Results

We found that heterozygous APE1/Ref-1 mice displayed a decrease in SV(8.00±0.01ul vs 9.75±0.96ul, p=0.01) and LVEF(58.75±2.63% vs 66.50±2.89%, p=0.007) compared to controls while the functional parameters of RV were similar. Interestingly, the circumferential strain rate of LV was significantly reduced in APE1/Ref-1 mice compared to controls(p<0.001), particularly in the systolic phase. In addition, the study showed that manually-calculated and AI-derived indices were within an acceptable margin of error, rendering the AI system reproducible and reliable in calculating volumetric parameters and strain of the mice's hearts.

Conclusions

This study demonstrated that LV global circumferential strain rate, along with SV and LVEF decreased in heterozygous APE1/Ref-1 transgenic mice. These parameters could serve as markers for assessing early functional changes of mice hearts in a non-invasive manner. Volumetric and strain indices measured by AI-based analysis of mouse CMR images are reproducible parameters for cardiovascular research in small animals.LV strain analysis of mice CMRTable of volumetric parameters
Cardiovascular risk progression into atrial fibrillation tracked with wearables: a report from mAFA II extension cohort
Authors: Guo Y , Lip G Y H
Published: November 2023

Background

Cardiovascular risk, e.g. obstructive sleep apnea (OSA), hypertension, frequent ectopic, are susceptible to atrial fibrillation (AF). Smartwearable-based detection for OSA, ectopics, AF and blood pressure have been tested in mobile health technology supported screening and integrated care for atrial fibrillation (mAFA II programme).

Objective

The present study aimed to investigate the AF occurrence after the cardiovascular risk identified with wearables.

Method

The risk factors which were monitored by wearables are as follows: i) OSA: more than 80% monitoring measures with 15 < apnea-hypopnea index (AHI) < 30 during sleep (intermediate risk）or with AHI ≥ 30 (high risk); ii) ectopics: the proportion of the premature beats among total monitored heart beats: 0.5%-10% among over heart beats (intermediate risk) or >10% premature beat (high risk); iii) High-risk blood pressure (BP): average 24-hour BP >130/80 mm Hg, reverse-dippers of BP, and pulse pressure over 60mmHg. Subjects aged over 18 years old, who used smart watch/wristband (Huawei Technologies Co., Ltd., Shenzhen, China) across China were enrolled into present study analysis between October 26, 2018 to Dec 14, 2022. The first detection AF episode were analyzed since the subjects were identified with high risk for AF, that was, intermediate- or high risk-OSA, high risk-blood pressure, intermediate- or high risk-ectopic by the wearables.

Results

There were 4.37 million subjects (78.6% male, mean age, SD, 37 ± 13 years) involving in the screening programme of mAFA II extension cohort. Among these, 611495 intermediate-risk ectopic, 5037 high-risk ectopic, 43777 intermediate-risk OSA, 22886 high-risk OSA, and 25892 high-risk blood pressure were identified (Figure 1). The rates of progressed into AF from identified cardiovascular risk were as follows: 0.97% (5936/611495) of 611495 intermediate-risk ectopic, 4.80% (242/5037) of high-risk ectopic, 1.09% (478/43777) of intermediate-risk OSA, 1.51% (345/22886) of high-risk OSA, and 1.74% (450/25892) of high-risk blood pressure, respectively.

Subjects identified with high-risk blood pressure were much likely to be early monitored with AF episode than other risk, with time to first AF (median, interquartile) of 10 (3-56) days (p<0.05). However, the above cardiovascular risk was possibly progressed into AF episode during five months.

Conclusion

Smartwearables facilitated the detection of risk factors, OSA, hypertension, frequent ectopic, which might progressed into AF during five months, calling for the effective proactive management on cardiovascular risk to reduce AF burden.Subjects involving in risk screening pro
Cardiac sympathetic hyperinnervation after myocardial infarction: a systematic review and qualitative analysis
Authors: Chen H S , Van Roon L , Schoones J , Zeppenfeld K , Deruiter M C , Jongbloed M R M
Published: November 2023

Background

Cardiac sympathetic hyperinnervation after myocardial infarction (MI) is associated with arrhythmogenesis and sudden cardiac death. The characteristics of cardiac sympathetic hyperinnervation remain largely underexposed.

Objective

To provide a systematic review on cardiac sympathetic hyperinnervation after MI taking into account: 1. Definition, experimental model and quantification method of hyperinnervation, and 2. Location, amount and timing of hyperinnervation, in order to obtain an overview of current knowledge and to expose gaps in literature.

Methods

References on cardiac sympathetic hyperinnervation were screened for inclusion. The included studies received a full-text review, and subsequently a quality appraisal was performed. Relevant data on cardiac sympathetic hyperinnervation were collected and qualitatively analysed.

Results

Our literature search identified 60 eligible studies performed between 2000 and 2022. Cardiac hyperinnervation is generally defined as an increased sympathetic nerve density or increased number of sympathetic nerves compared to another control group (100%). Studies were performed in a multitude of experimental models, but most commonly in male rats with permanent LAD ligation (male: 63%, rat: 68%, permanent ligation: 93%, LAD: 97%). Hyperinnervation seems to occur mainly in the borderzone. Quantification after MI relied on calculating the nerve density in regions of interest in µm2/mm2 (41%) or in percentage of nerve fibers (46%) and the reported amount showed a great variation ranging from 439 to 126718 µm2/mm2. Remarkably, cardiac sympathetic hyperinnervation seems to be present at all timepoints starting from 3 days onwards to >3 months without an evident peak, although studies on structural evaluation over time and in the chronic phase were scarce.

Conclusion

Cardiac sympathetic hyperinnervation occurs already at 3 days after MI mainly in the borderzone and remains present at all timepoints. It is most commonly studied in male rats with permanent LAD ligation. The amount of hyperinnervation differs greatly between studies, possibly due to the differential quantification methods. Further studies are required that evaluate cardiac sympathetic hyperinnervation over time and in the chronic phase, in transmural sections, in the female sex, and in MI with reperfusion.
Factors for incorrect automated atrial fibrillation identification in large-scale screening
Authors: Zink M D , Lueken M , Leonhardt S , Freedman B , Keszei A P , Mischke K , Marx N
Published: November 2023

Introduction

Correct heart rhythm diagnosis in single-lead electrocardiogram (ECG) screening for atrial fibrillation (AF) is paramount for large-scale implementation.

Aim

Examine the accuracy of automated AF detection and identify patient factors and ECG signal quality leading to incorrect measurements based on human overread and a machine learning approach.

Methods

Screening for AF using a single-lead ECG device (MyDiagnostick, Biomedical Systems, Netherlands) was performed on 7295 customers in community pharmacies in Germany. ECG rhythm strips were blinded for automatic heart rhythm analysis and were analyzed by human overread for heart rhythm and signal quality from excellent to uninterpretable (Figure 1A). A machine learning-based estimation was used to score signal quality (MLSQE). Inclusion criteria were 30 seconds of consecutive ECG recording and complete data of pharmacy visit. In total, 6732 participants were eligible for analysis.

Results

An incorrect automated heart rhythm diagnosis was found for 206 subjects (false positive: 112; false negative: 94). By human overread 80% (N=5377) of the recorded ECGs were rated with excellent and good signal quality in which heart rhythm diagnosis based on visible atrial electrical activity (Figure 1A). The proportion of incorrect automated rhythm diagnosis was higher in ECGs with poorer signal quality. A regression analysis revealed patient characteristics prone to incorrect heart rhythm diagnosis included male sex (OR 1.61 95% confidence interval (CI) 1.22-2.13, P<0.001), age (per year OR 1.06 95%CI 1.04-1.09, P<0.001), body height (per cm OR 1.02 95%CI 1.00-1.03, P=0.03), and body weight (per kg OR 0.99 95%CI 0.98-0.99, P=0.005). A multivariate model for prediction of correct heart rhythm diagnosis showed a modest area under the curve (AUC) of 0.65 (sensitivity 61%, specificity 58%; Figure 1B). The prediction improved by adding information on signal quality rated by human overread (AUC 0.77, sensitivity 77%, specificity 62%) and even more by the machine-learning based MLSQE score (AUC 0.87, sensitivity 71%, specificity 90%).

Conclusion

The patient characteristics prone to incorrect automated heart rhythm diagnosis of male sex, older age, greater height, and lower body weight probably reflect the target population of many AF screening cohorts. Automated MLSQE scoring for ECG signal quality could improve accuracy in clinical use and potentially reduces the need for cumbersome and time-consuming human overread.Figure 1A - Signal quality by human rating and proportion of incorrect automated heart rhythm diagnosis. B - Prediction of correct heart rhythm diagnosis. Blue line - Multivariate model with forward selection considering age, height, weight, body mass index, congestive heart failure, hypertension, diabetes mellitus, vascular disease, stroke/TIA and sex. Purple line - Model with human signal quality (SQ) score. Green line – Model with MLSQE score.
Atrial fibrosis and local right atrial inflammation are characteristic of strenuous, but not moderate exercise, and underlie increased AF inducibility in heavily trained rats
Authors: Alcarraz A , Meza-Ramos A , Rubies C , Sanz-De La Garza M , Mont L , Batlle M , Guasch E
Published: November 2023

Introduction

The U-shaped relationship between exercise load and atrial fibrillation (AF) risk, where moderate exercise is protective but strenuous training increases the risk of AF, is currently well accepted (1, 2). Clinical and experimental data suggest that atrial fibrosis and parasympathetic tone (PT) enhancement may underlie the excess risk of AF in endurance athletes (3). Delving into the atrial differences between moderate exercise and strenuous training may be important to understand the pathophysiology of exercise-induced AF.

Purpose

To compare the atrial structural, electrophysiological and molecular remodelling occurring after long-term moderate and strenuous exercise.

Methods

Male Wistar rats were randomly assigned to sedentary (SED), moderate (MOD, 35 cm/s, 45 minutes) or high intensity exercise (INT, 60 cm/s, 60 minutes) for 16 weeks. An electrocardiogram (ECG) and electrophysiological study (EPS) were performed before sacrifice. Left (LA) and right (RA) atrial samples were collected for fibrosis assessment and a mRNA array.

Results

After the exercise protocol, weight of SED rats was higher (486±77 g) compared with both the MOD (377±28 g) and INT groups (385±43 g). In the ECG (Figure 1), INT rats presented a prolonged P-wave compared with SED and MOD. Both trained groups presented with significant bradycardia compared with SED, along with enhanced PT (heart rate variability: low to high frequency ratio). The remaining ECG parameters were similar between groups. Consistent with an enhanced PT, the Wenckebach cycle length was similarly prolonged in both trained groups in the EPS. Conversely, the sinus node recovery time was prolonged in INT rats compared with SED and MOD. AF inducibility increased from SED to MOD to INT. Myocardial fibrosis was measured in atrial samples stained with Sirius red. In both the RA and LA, fibrosis was significantly higher in the INT group (6,3±0.8 %) compared with the SED (4,4±0.2 %) and MOD (4,3±0.5 %) groups. An mRNA array showed large differences between atria. 384 and 419 genes were deregulated between INT and MOD (nominal p<0.05) in the RA and LA, respectively. Only 19 genes were consistent between both atria. In pathway analyses, the inflammatory response pathway was enriched (upregulation) in the RA, but not in the LA, of INT rats compared with MOD (Figure 2).

Conclusions

In healthy rats, strenuous training promoted a differential, pathological remodelling involving atrial fibrosis and sinus node dysfunction, compared with moderate exercise. Local inflammation may play a role in strenuous exercise-induced fibrosis in the RA. PT enhancement was similar in both groups.Figure 1.Figure 2.
Estrogen-induced phenotype in hiPSC-derived cardiomyocytes of a woman affected by both Long QT Syndrome Type 2 and Polycystic Ovary Syndrome
Authors: Bastaroli F , Maniezzi C , Dusi V , Mura M , Lodola F , Zaza A , Gnecchi M
Published: November 2023

Introduction

Long QT Syndrome (LQTS) is an arrhythmogenic disorder caused either by genetic alteration or by exogenous factors. Polycystic Ovary Syndrome (PCOS) is a disease associated with high levels of testosterone and low levels of estrogen (E2). It has been suggested that hormones can influence the occurrence of malignant cardiac events in LQTS type 2 (LQT2) women, carriers of mutations on the potassium channel (hERG). However, the precise mechanisms governing this process still need to be clarified.

Purpose

We studied a patient affected by both LQT2 and PCOS who started experiencing cardiac symptoms after initiation of hormonal replacement therapy. We observed a correlation with the occurrence of arrhythmic events and the irregular assumption of the hormonal replacement therapy, thus we aim to dissect the underlying mechanism in patient-in-a-dish cardiac cellular model.

Methods

Induced Pluripotent Stem Cells (hiPSC) were generated from a woman affected by both LQT2 and PCOS and from a healthy donor, and then differentiated into cardiomyocytes (hiPSC-CMs). hiPSC-CMs were stimulated with E2 10nM for five time points (1, 5, 10, 15 and 30 minutes). The expression of potassium channel hERG, and of the G-coupled estrogen receptor (GPER) regulating the fast non-genomic pathway, were quantified after E2 stimulation at different time points by In Cell Western (ICW). The Unstimulated sample were used to normalize GPER and hERG expression to 100%. Electrophysiological experiments were performed using the whole-cell patch-clamp technique in current-clamp mode to record spontaneous action potentials (APs). AP duration at 30%, 50% and 90% repolarization (APD30, APD50 and APD90) was quantified. During spontaneous activity, AP duration values were rate-corrected with Bazett’s formula, thus obtaining cAPD.

Results

LQT2 hiPSC-CMs express higher levels of GPER (p<0.05) and hERG (p<0.01) than healthy hiPSC-CMs. A significant decrease in GPER expression was detected during 10nM E2 stimulation in healthy cardiomyocytes at the five time points (p<0.0001), while any difference was detected in hERG expression levels. E2 stimulation at different time points did not affect neither GPER nor hERG expression in LQT2 hiPSC-CMs. In LQT2 hiPSC-CMs, APDC values were significantly increased (p<0.0001) compared to healthy cells; pre-incubation with E2 for 10 minutes significantly shortened cAPD50 and increased spontaneous firing rate. In healthy hiPSC-CMs, E2 had no effect.

Conclusions

The hiPSC-CM model reproduces the LQT2 clinical phenotype. cAPD50 shortening by E2 was unexpected based on the proarrhythmic effect in the patient. The mechanism of LQT2-specific effects of E2 are under investigation.
Mutation in PDGFRbeta: a potential new pathogenic variant for mitral valve prolapse
Authors: Wu H W , Van Wijngaarden A L , Mousavi Gourabi B , Smits A M , Barge-Schaapveld D Q C M , De Vries A A F , Jukema J W , Kruithof B P T , Ajmone Marsan N
Published: November 2023

Background

Mitral valve prolapse (MVP) due to myxomatous degeneration is characterized by familial clustering, but few pathogenic genes have been identified. In a genetic screening program for MVP patients, we identified a platelet-derived growth factor receptor β (PDGFRβ)-E162K missense variant in a family with a bi-leaflet MVP phenotype in four affected family members. PDGFRβ is a receptor tyrosine kinase, which plays an important role in vascular development.

Purpose

In this study, we investigated whether the E162K substitution in PDGFRβ could lead to mitral valve abnormalities.

Methods

To assess the functional effects of the missense variant, proliferation and migration assays were performed using HeLa cells overexpressing wild-type (WT) or mutant PDGFRβ. Immunostainings were performed to determine PDGFRβ expression in the diseased valves from a family member undergoing surgical operation and from additional patients operated for MVP. Mouse models were created with the mouse equivalent of the human PDGFRβ-E162K variant (PDGFRβ-E161K) using CRISPR/CAS9. The variant was not lethal and a total of 12 homozygous PDGFRβ-E161K-/- mice, 11 heterozygous PDGFRβ-E161K+/- mice, and 7 WT mice were subjected to transthoracic echocardiography. In addition, histology was performed in all 30 mice to detect potential valvular defects.

Results

Stimulated HeLa cells expressing PDGFRβ-E162K showed reduced proliferation and migration, suggesting a loss of function of the mutant receptor. PDGFRβ was expressed in human diseased mitral valves. Echocardiographic evaluation revealed a significant larger mitral valve annulus diameter in both PDGFRβ-E161K+/- and PDGFRβ-E161K-/- compared to WT (WT: 1.97 mm; PDGFRβ-E161K+/-:2.13, p=0.031; PDGFRβ-E161K-/-: 2.42 mm, p<0.0001). Histological data in PDGFRβ-E161K-/- mice showed significant leaflet thickening in the free edge (FE) of the posterior mitral valve leaflet (PMVL) compared to WT (WT: 72.34 ɥm; PDGFRβ-E161K-/-: 109.6 ɥm, p=0.040) and a larger leaflet area of the PMVL compared to WT (WT: 25280 ɥm²; PDGFRβ-E161K-/-: 44494 ɥm², p=0.020). Moreover, an altered organization of the extracellular matrix reminiscent of the myxomatous degeneration in MVP was observed.

Conclusions

The PDGFRβ-E162K variant is associated with familial MVP and alters the function of PDGFRβ. Mice harboring this mutation display mitral valve defects and can be used as a model for mitral valve disease.