bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vitamin D in cardiac fibroblasts: new evidence for a TRP-mediated non-genomic pathway
Authors: Saliba Y S , Nakhl S N , Chedid El Helou M C H , Fares N 
Published: October 2024

Abstract

Background/Introduction
Vitamin D’s (VD) role transcends phosphocalcic metabolism to affect different systems, notably the cardiovascular system in health and diseases. Beyond its genomic effect, VD act through non-genomic calcium (Ca2+) signaling pathways, hinting at a broader spectrum of physiological impacts. Despite the established interactions with cardiomyocytes via the Vitamin D Receptor (VDR), little is known about VD and cardiac fibroblast, a pivotal cell player in cardiac function and disease.

Purpose
This research aims to reveal Vitamin D's role in modulating cardiac fibroblast function through Transient Receptor Potential (TRP) channels.

Methods
Utilizing primary cardiac fibroblasts from human and rats, our investigation focused on intracellular calcium signaling. Through Ca2+ imaging techniques combined to synthetic fluorescent VD analogue, we explored Vitamin D's behavior within the cell. The study further employed biochemical assays to elucidate the interaction between VDR on the cell membrane and TRP channels signaling, providing a detailed map of the cellular choreography orchestrated by VD within cardiac fibroblasts. In addition, in vitro and ex vivo heart perfusion experiments were incorporated to assess cardiac cGMP production in response to VD.

Results
Our findings reveal a unique pathway wherein VD induces Ca2+ oscillations in human and rat cardiac fibroblasts specifically through the TRPC3 channel, sidelining other calcium sources. This process is regulated by the interaction between TRPC3 and the membrane-bound VDR, harmonizing with phospholipase C signaling to a crescendo of cGMP production in cardiac fibroblasts, and across the entire heart. This was associated with less pro-fibrotic potential of cardiac fibroblasts.

Conclusion
This study provides the first evidence of a TRP-mediated, VD non-genomic pathway within human and rat cardiac fibroblasts. Our findings herald a promising horizon for investigating vitamin D’s antifibrotic potential in heart disease.
Characterization of knock-in zebrafish models with a novel SLC4A3 variant identified in a short QT syndrome family
Authors: Zhu M , Wang Q , Horie M , Ogawa M , Kikuchi K , Ohno S 
Published: October 2024

Abstract

Background
Short QT syndrome (SQTS) is one of the lethal inherited arrhythmia syndromes leading to ventricular fibrillation (VF) and cardiac death. It is mainly caused by pathogenic variants in ion channel related genes, especially KCNH2 which produces IKr. Recently, SLC4A3 encoding a membrane-localized anion exchanger 3 (AE3) that regulates intracellular pH (pHi), has been reported as a causative gene for SQTS. However, the molecular mechanism of SLC4A3 variants which cause SQTS remains unclear.

Purpose
Functional characterization of a novel SLC4A3 variant identified in a SQTS family.

Methods
We performed target gene and whole exome sequencing to detect pathogenic variants in a family with SQTS. Patch-clamp analyses were performed to determine the electrophysiological properties using HEK293 cells. We constructed stable cell lines expressing wild-type (WT) or the SLC4A3 variant based on HEK293 cells. To evaluate the intracellular pH (pHi) level, we measured pHi using BCECF-AM via time-lapse microscopy. To clarify the pathogenesis of the SLC4A3 variant in vivo, we injected CRISPR-Cas9 and a repair template into one-cell stage zebrafish embryos and established a SLC4A3 knock-in (KI) zebrafish model (hereafter referred to as slc4a3 zebrafish). Action potential durations (APD) were recorded in slc4a3 zebrafish at 3 days post-fertilization (dpf).

Results
We identified two novel variants in KCNH2 (c.280 c&gt;t, p.H70Y) and SLC4A3 (c.1059 c&gt;a, p.N353K) in a SQTS patient. Both variants were co-segregated in the patient’s family with short QT intervals (Figure A). By electrophysiological analysis, KCNH2-H70Y did not increase IKr. We over-expressed KCNH2 (WT and H70Y), KCNQ1, and KCNJ2 in the SLC4A3 stable cell lines (WT and N353K) though no increase of IKr, IKs, and IK1 was observed. In the analysis of pHi, cells expressing SLC4A3-N353K showed significantly slower pHi alternations than those with WT, indicating the loss-of-function effect of transport kinetics in the regulation of pHi. In the electrophysiological analysis of the slc4a3 zebrafish, which harbors the paralogous variant of SLC4A3-N353K, APD20, 50, and 70 were significantly shortened in the slc4a3 KI zebrafish (HOMO) compared to the control (WT), providing evidence for the shortened QT interval with the SLC4A3 variant in vivo (Figure B). Furthermore, slc4a3 zebrafish developed severe cardiac edema (HET and HOMO: Figure C, arrows) with no gross morphological defects in other organs, which may indicate the specific role of SLC4A3-N353K in cardiac function.

Conclusion
We identified a novel SLC4A3 variant, p.N353K, in a family with SQTS and revealed its contributions to the pHi control and the shortened APD. Further analysis will be necessary to clarify the mechanism by which SLC4A3-N353K causes QT shortening.
Partial deletion of the Akap1 gene promotes abnormalities in gut barrier function, gut microbiota composition and cardiac function during cardiovascular aging in mice
Authors: Ioele D , Paolillo R , D'apice S , Coretti L , Lama A , Polese P , Carotenuto M , Mattace Raso G , Mollica M , Lembo F , Esposito G , Perrino C 
Published: October 2024

Abstract

Background
Cardiovascular aging is characterized by mitochondrial dysfunction, changes in intestinal permeability and microbiota composition. Mitochondria-targeted A-kinase anchoring proteins (mitoAKAPs) are a group of structurally diverse proteins binding the regulatory subunits of protein kinase A (PKA), and targeting PKA at discrete intracellular locations. We analyzed the effects of global partial genetic deletion of Akap1 on intestinal barrier permeability, microbiota composition, inflammation, and cardiac function during aging in mice.

Purpose
The proposal of this study was to determine the role of mitoAKAPs in the gut-heart axis during cardiovascular aging.

Methods
Young (4-6-month) and old (18-24-month) genetically modified Akap1+/+ and Akap1+/− mice of either sex underwent evaluation of cardiac function by transthoracic echocardiography. To evaluate gut barrier integrity, we analyzed expression levels of intestinal junction proteins occludin (Ocln), zonulin (Tjp1) in colonic samples and FITC-dextran permeability in vivo, circulating levels of Tumor Necrosis Factor-alpha (TNF-alpha), Lipopolysaccharide (LPS), Interleukin-1 (IL-1) and Interleukin-10 (IL-10). Fecal microbial composition was evaluated by Illumina Mi-Seq, Gut microbiota differences based on 16S rDNA sequencing at genus and species taxonomic levels were identified using linear discriminant analysis (LDA) combined with effect size (LEfSe) algorithm. Finally, faecal microbiota transplantation (FMT) was performed for five weeks to test whether modification of gut microbiota composition can affect cardiac function.

Results
A reduction in % left ventricular shortening (FS%) was observed in young and old Akap1+/- mice compared to Akap1+/+ mice. This finding was associated to increased intestinal permeability, as indicated by reduced mRNA levels of Ocln and Tjp1, increased LPS traslocation across intestinal epitelium into blood in 24m Akap1+/- mice compared to Akap1+/+. Through the analysis of the microbial signature, we observed the different bacterial species present in the microbiota of the experimental groups. FMT of bacteria species from old Akap1+/− to young Akap1+/+ mice induced gut abnormalities and cardiac dysfunction, while FMT from young Akap1+/+ donors ameliorated cardiac dysfunction in old Akap1+/+ mice.

Conclusions
MitoAKAPs play a crucial role in the maintenance of intestinal barrier function, gut microbiota composition and cardiac function during aging. Modulation of the composition of the intestinal microbiota influences intestinal permeability and cardiac function. MitoAKAPs could represent an important diagnostic and therapeutic target for cardiac and intestinal dysfunction.
Increased endothelial cell uptake of erythrocyte-derived extracellular vesicles carrying arginase-1 induces endothelial dysfunction in type 2 diabetes
Authors: Collado A , Humoud R , Kontidou E , Swaich J , Yang J , Mahdi A , Tengbom J , Zhou Z , Pernow J 
Published: October 2024

Abstract

Background
Recently, we have demonstrated that red blood cells (RBCs) from individuals with type 2 diabetes (T2D-RBCs) induce endothelial dysfunction. However, the mechanism by which RBCs communicate with the vessel is unknown. Extracellular vesicles (EVs) are actively secreted by practically all cell types, including RBCs, and represent a novel mechanism of intercellular communication. However, the involvement of EVs from RBC in the development of endothelial dysfunction remains to be elucidated.

Purpose
This study was designed to test the hypothesis that EVs are key players in the communication and the transfer of signalling between RBCs and the vascular endothelium to induce endothelial dysfunction in T2D.

Methods
RBCs from T2D patients and age-matched healthy controls (H-RBCs) were incubated for 18h with Krebs-Henseleit buffer (20% haematocrit) for EV release. RBC-derived EVs in the conditioned medium were isolated using a membrane affinity column. The EVs were co-incubated with mouse aortae to evaluate endothelium-dependent relaxation and with endothelial cells for expression analysis. The uptake of the EVs by endothelial cells and their content of arginase-1 were determined. The functional involvement of arginase was investigated using pharmacological interventions and expression analyses. All animal experiments were performed according to the principles of laboratory animal care (NIH Publication no. 85-23 revised 1985) and human procedures according to the declaration of Helsinki with approval by the Swedish Ethical Review Authority.

Results
The uptake of EVs derived from T2D-RBCs by endothelial cells was 2-fold greater than that of EVs from H-RBCs (Fig. 1A-B). Inhibiting the uptake of EVs derived from T2D-RBCs by the addition of heparin during the co-incubation rescued the endothelial function (Fig. 1C). Arginase-1 was detected in RBC-derived EVs (Fig. 2A). Arginase-1 mRNA and protein levels were increased in endothelial cells following co-incubation with EVs derived from T2D-RBCs (Fig. 2B-D). Additionally, the increase in arginase-1 protein induced by EVs derived from T2D-RBCs in endothelial cells was observed also following mRNA silencing for arginase-1 (Fig. 2E-F). Finally, mouse aortae co-incubated with EVs derived from T2D-RBCs in the presence or absence of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid significantly attenuated the impairment in endothelial function induced by EVs derived from T2D-RBCs (Fig. 2G).

Conclusion
Increased uptake of RBC-derived EVs by the endothelial cells is an important feature of the endothelial dysfunction induced by these EVs in T2D. In addition, these EVs carry arginase-1 protein to induce endothelial dysfunction. The mechanism underlying the increased uptake of EVs in target cells is of importance to identify in future studies, as it could lead to new treatment strategies.
Loss of IDH1 and IDH2 in macrophages induces pathological phenotypes in cardiomyocytes
Authors: Pennoyer P , Shumliakivska M , Fleck F , Zanders L , Zeiher A , Dimmeler S 
Published: October 2024

Abstract

Introduction
The clonal expansion of hematopoietic stem cells can be induced by a variety of age-related somatic mutations, a phenomenon known as "clonal hematopoiesis of indeterminate potential" (CHIP). CHIP is associated with an increased incidence and poor outcomes in patients with cardiovascular disease. The mechanisms underlying the crosstalk between CHIP cells and cardiac tissue are yet to be elucidated. Rare mutations in the metabolism-regulating isocitrate dehydrogenases encoding genes IDH1 and IDH2 have been identified as AML-like and cardiovascular high-risk CHIP-driving mutations in patient cohorts. However, the potential paracrine effects of these mutations in immune cells on cardiac tissue are unknown. Therefore, we assessed the impact of IDH1 and IDH2 mutations on the paracrine activities of macrophages.

Methods and Results
To gain first insights into the functional consequences of the IDH mutations, we used the AlphaMissense algorithm, which predicts the impact of mutations on protein function. IDH1 and IDH2 mutations identified in our patient cohorts were predicted to induce pathological alterations of protein function with a score &gt;0.99. Therefore, we assessed the effects of silencing of the two genes in primary human CD14+ M0 macrophages on the paracrine activity on neonatal rat cardiomyocytes. Transfection with siRNA pools targeting IDH1 and IDH2 to mimic CHIP-driving conditions reduced mRNA abundance by 78% and 73%, respectively (both p&lt;0.05). To assess the impact of IDH-silencing on cardiovascular cells, cardiomyocytes were treated with the supernatant of the macrophages. Interestingly, supernatants of IDH1 silenced macrophages significantly increased apoptosis of cardiomyocytes (8.6-fold increased expression of cleaved caspase-3; p&lt;0.05) and reduced beating frequency. In addition, supernatants of IDH1 silenced macrophages induced a 1.5-fold increase in cardiomyocyte hypertrophy (p&lt;0.01), whereas silencing of IDH2 showed no effect on cardiomyocyte hypertrophy and apoptosis. However, supernatants of both IDH1 and IDH2 silenced macrophages resulted in significantly increased numbers of bi- and multinucleated cardiomyocytes.
Conclusion: Loss of isocitrate dehydrogenases in human macrophages affects cardiomyocyte functions in a paracrine fashion. Particularly silencing of IDH1 in macrophages introduced cardiomyocyte hypertrophy, apoptosis, and bi- and multinucleation, and reduced contractile function. Ongoing studies will address how IDH1 and IDH2 silencing-induced alterations in macrophages control their paracrine activity on cardiomyocytes.
Evaluation of serum levels of sCD40, sCD40L and s4-1BB in advanced heart failure and after heart transplant
Authors: Monteiro V , Torres L , Carneiro R , Cunha C , Figueira F , Matta M , Silva I , Tchaick R , Paola A 
Published: October 2024

Abstract
Heart failure is one of the most important problems in public health. Although big advances had been reached in treatment, the prognosis of advanced heart failure is still reserved and the heart transplant is the main therapy for this stage of disease. Allograft rejection is responsible for mortality in transplantation patients and the diagnosis of this complication is made through an invasive diagnostic method – the cardiac biopsy. The inflammatory response has been described in cardiovascular disease and in allograft rejection process.
The objective of this study is to evaluate levels of sCD40, sCD40L and s4-1BB (inflammatory biomarkers) in advanced heart failure and post heart transplant with allograft rejection comparing to normal individuals and post heart transplant patients with no allograft rejection.
The study population comprised 38 patients undergoing heart transplant in our center. Fifteen patients had biomarkers dosed before heart transplant and twenty three patients had dosed just after procedure. In this group, six patients were enrolled in the study for clinical suspicion of rejection. Nineteen health persons composed the control group with age between 18 and 49 years. Plasma dosage of sCD40, sCD40L e s4-1BB was made by enzyme linked immunosorbentassay (ELISA). Mann-Whitney test, Wilcoxon and t test were used to analyse dates. Statistical analysis used GraphPad®Prism6 and the value p&lt; 0,05 was considered statistical significant.
Allograft rejection occurred in 6,26% of studied patients. There was no statistical difference in age, sex, comorbities as hypertension, diabetes or etiology of cardiomyopathy. Serum levels of sCD40, sCD40L e s4-1BB were higher in patients with advanced heart failure comparing to controls (p&lt; 0,0001). There was no difference in these levels of sCD40 (p = 0,74) e sCD40L (p = 0,44) between groups with and without rejection. Levels of s4-1BB were significantly lower in patients with allograft rejection (p= 0,02). The sCD40/PCR and s4-1BB/PCR indexs were significantly higher in the group of patients with allograft rejection (p =0,02 e p= 0,0001).
We concluded that sCD40, sCD40L e s4-1BB are biomarkers of severe heart failure. The serum level of s4-1BB could be a potential biomarker of allograft rejection and the association of sCD40 and s4-1BB with PCR could be a better strategy to this.
Detecting epicardial connection through intercaval bundle using intra-atrial activation sequence during right pulmonary vein pacing
Authors: Chikata A , Kato T , Usuda K , Fujita S , Usuda K , Matsuura S , Maruyama M , Otowa K , Kusayama T , Tsuda T , Hayashi K , Takamura M 
Published: October 2024

Abstract

Background
An epicardial connection (EC) through the intercaval bundle (EC-ICB) between the right pulmonary vein (RPV) and the right atrium (RA) is one of the reasons for the need of carina ablation for PV isolation.

Purpose
We evaluated the intra-atrial activation sequence during RPV pacing after failure of ipsilateral RPV isolation and sought to identify specific conduction patterns in the presence of the EC-ICB.

Methods
This study included 223 consecutive patients undergoing initial catheter ablation of atrial fibrillation. If the RPV was not isolated by circumferential ablation or reconnected during the waiting period, an exit map during mid RPV carina pacing was created. If the earliest site of the exit map was the RA, the patient was classified into the EC-ICB group. During the exit map, intra-atrial activation sequence and RPV-HRA time were evaluated.

Results
First-pass isolation of the RPV was not obtained in 36 patients (16.1%), and 22 patients (9.9%) showing reconnection. Among them, 12 patients were classified into the EC-ICB group and 28 patients into the Non-EC-ICB group after excluding multiple ablation lesion sets or incomplete mapping. Intra-atrial activation sequence showed different patterns between the two groups. RPV-HRA time was significantly shorter in the EC-ICB group compared to the Non-EC-ICB group (69.2 ± 15.2 ms v.s. 148.6 ± 51.2 ms. P&lt;0.001), and RPV-HRA time&lt;89.0ms was highly predictive for existence of the EC-ICB (sensitivity 91.7 %, specificity 89.3 %).

Conclusions
The EC-ICB can be effectively detected by intra-atrial sequencing during RPV pacing and RPV-HRA time&lt;89.0ms was highly predictive.
Oxct1 regulates cardiomyocyte PANoptosis in acute myocardial infarction via succinylating Tfam
Authors: Li X , Ji Z J , Tao Z X , Huang R , Zhang R , Li Y J , Ma G S 
Published: October 2024

Abstract

Background
Myocardial ischemia leads to various forms of programmed cell death in cardiomyocytes, resulting in acute myocardial infarction (AMI) and the development of heart failure in the long term. PANoptosis is a unique cell death regulatory mechanism orchestrated by the PANoptosome complex, which regulates and intersects multiple forms of programmed cell death. Oxct1 has been demonstrated to play crucial roles in tumors, pressure-overloaded hearts, and cardiac endothelial cells. However, whether Oxct1 is involved in the regulation of PANoptosis and correlated mechanisms during AMI remains unclear.

Purpose
To elucidate the role of Oxct1 in cardiomyocytes during AMI and uncover the potential mechanisms.

Methods
The myocardial infarction model induced by anterior descending branch ligation and the primary cardiomyocytes hypoxia model were employed in our experiments. Small interfering RNA (siRNA) and adenovirus were constructed to knock down and overexpress Oxct1 for altering its expression in cardiomyocytes in vitro. Cardiomyocyte-specific knockout mice were constructed to alter Oxct1 expression in vivo. PANoptosis characteristic measurement, including Z-DNA binding protein 1(Zbp1), pyroptosis markers, apoptosis markers, necroptosis markers, ROS, and mitochondrial morphology, were performed to verify the ability of Oxct1 to regulate the PANoptosis of cardiomyocytes. Cardiac morphological, structural, and functional changes were measured to assess the effect of Oxct1 on AMI. RNA sequencing was performed to identify downstream pathways. Immunoprecipitation +Mass spectrometry and co-immunoprecipitation were performed to identify the specific binding factors of Oxct1.

Results
We found that the expression of Oxct1 was significantly elevated after AMI. Besides, gain- and loss-of-function experiments were constructed both in vitro and in vivo. Functionally, Oxct1 knockdown significantly enhanced cardiomyocyte vitality, reduced ROS production and mtDNA cytoplasmic release in hypoxic cardiomyocytes. In vivo, Oxct1cko mice manifested reduced infarct size, improved cardiac function and alleviated cardiac fibrosis by mitigating PANoptosis. However, Oxct1 overexpression resulted in the opposite effects. Afterwards, RNA-seq analysis results showed that cytosolic DNA-sensing pathway was significantly enriched in Oxct1 knockdown cardiomyocytes. Mechanistically, Oxct1 could bind to mitochondrial transcription factor A(Tfam) and increased its succinylation, promoting Tfam degradation. Downregulation of Tfam resulted in ROS production and mtDNA damage, while mtDNA released into cytoplasm could activate Zbp1 and induce cascade reaction of PANoptosis.

Conclusion
This study demonstrates that Oxct1 promotes Tfam degradation through succinylation, exacerbating ROS production, mtDNA damage and cytoplasmic release, ultimately leading to cardiomyocyte PANoptosis in AMI.