bims-cesiha 2021-03-21 papers

bims-cesiha

Biomed News

on Cell signalling in the heart

Issue of 2021‒03‒21
twenty-four papers selected by
Danae Angelidaki
Max Planck Institute for Biology of Ageing

Combined Administration of Metformin and Atorvastatin Attenuates Diabetic Cardiomyopathy by Inhibiting Inflammation, Apoptosis, and Oxidative Stress in Type 2 Diabetic Mice.
Cardiomyocyte protective effects of thyroid hormone during hypoxia/reoxygenation injury through activating of IGF-1-mediated PI3K/Akt signalling.
Mitochondrial ROS and mitochondria-targeted antioxidants in the aged heart.
GATA-targeted compounds modulate cardiac subtype cell differentiation in dual reporter stem cell line.
Identification of a CTRP9 C-Terminal polypeptide capable of enhancing bone-derived mesenchymal stem cell cardioprotection through promoting angiogenic exosome production.
Regulation of cardiomyocyte DNA damage and cell death by the type 2A protein phosphatase regulatory protein alpha4.
Cardiomyocyte depolarization triggers NOS-dependent NO transient after calcium release, reducing the subsequent calcium transient.
miR-106a-363 cluster in extracellular vesicles promotes endogenous myocardial repair via Notch3 pathway in ischemic heart injury.
Cardiac retinoic acid levels decline in heart failure.
NLRP3-mediated pyroptosis aggravates pressure overload-induced cardiac hypertrophy, fibrosis, and dysfunction in mice: cardioprotective role of irisin.
Single Cell RNA-Sequencing Uncovers Paracrine Functions of the Epicardial-Derived Cells in Arrhythmogenic Cardiomyopathy.
Regulation of Nrf2 signaling pathway in heart failure: Role of extracellular vesicles and non-coding RNAs.
FoxO1 is required for high glucose-dependent cardiac fibroblasts into myofibroblast phenoconversion.
Human induced pluripotent stem cell-derived three-dimensional cardiomyocyte tissues ameliorate the rat ischemic myocardium by remodeling the extracellular matrix and cardiac protein phenotype.
Exosomal LINC00174 derived from vascular endothelial cells attenuates myocardial I/R injury via p53-mediated autophagy and apoptosis.
Xbp1s-FoxO1 axis governs lipid accumulation and contractile performance in heart failure with preserved ejection fraction.
Remodelling of adult cardiac tissue subjected to physiological and pathological mechanical load in vitro.
Macrophage p47phox Regulates Pressure Overload-Induced Left Ventricular Remodelling by Modulating IL-4/STAT6/PPARγ Signaling.
Branched-chain α-ketoacids are preferentially reaminated and activate protein synthesis in the heart.
A DARPin targeting activated Mac-1 is a novel diagnostic tool and potential anti-inflammatory agent in myocarditis, sepsis and myocardial infarction.
Cardiac Tissues From Stem Cells: New Routes to Maturation and Cardiac Regeneration.
Cardioprotective action of chia (Salvia hispanica L.) in ovariectomized rats fed a high fat diet.
Sparsely methylated mitochondrial cell free DNA released from cardiomyocytes contributes to systemic inflammatory response accompanied by atrial fibrillation.
Spatiotemporal single-cell RNA sequencing of developing chicken hearts identifies interplay between cellular differentiation and morphogenesis.

Front Cell Dev Biol. 2021 ;9 634900

Combined Administration of Metformin and Atorvastatin Attenuates Diabetic Cardiomyopathy by Inhibiting Inflammation, Apoptosis, and Oxidative Stress in Type 2 Diabetic Mice.

Weikun Jia, Tao Bai, Jiang Zeng, Zijing Niu, Daogui Fan, Xin Xu, Meiling Luo, Peijian Wang, Qingliang Zou, Xiaozhen Dai.

  Diabetic cardiomyopathy (DCM), a common complication of diabetes mellitus, may eventually leads to irreversible heart failure. Metformin is the cornerstone of diabetes therapy, especially for type 2 diabetes. Statins are widely used to reduce the risk of cardiovascular diseases. In this study, we aimed to investigate whether the combined administration of metformin and atorvastatin could achieve superior protective effects on DCM and to elucidate its molecular mechanism. Here, db/db mice (9-10 weeks old) were randomly divided into four groups, including sterile water group (DM), metformin group (MET, 200 mg/kg/day), atorvastatin group (AVS, 10 mg/kg/day), and combination therapy group (MET + AVS). Mice were treated with different drugs via gavage once per day for 3 months. After 3 months of treatment, the pathological changes (inflammation, fibrosis, hypertrophy, and oxidative stress makers) were detected by histopathological techniques, as well as Western blotting. The H9C2 cardiomyocytes were treated with palmitate (PAL) to mimic diabetic condition. The cells were divided into control group, PAL treatment group, MET + PAL treatment group, AVS + PAL treatment group, and MET + AVS + PAL treatment group. The effects of MET and AVS on the cell viability and inflammation of H9C2 cells subjected to PAL condition were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, immunofluorescence staining, and Western blotting. Both MET and AVS prevented diabetes-induced fibrosis, hypertrophy, and inflammation. The combination therapy showed superior effects in protecting myocardial tissue against diabetes-induced injury. Mechanistically, the combination therapy significantly inhibited oxidative stress and the expression levels of inflammation-related proteins, e.g., NLRP3, caspase-1, interleukin-1β (IL-1β), Toll-like receptor 4 (TLR4), and P-p65/p65, in both cardiac tissues and H9C2 cells. TUNEL assay showed that the combination therapy significantly attenuated the apoptosis of cardiomyocytes; decreased the expression level of pro-apoptotic-related proteins, such as cleaved caspase-3 and BAX; and enhanced the expression level of anti-apoptotic protein (Bcl-2). Furthermore, the combination therapy remarkably upregulated the expression levels of 5'-AMP-activated protein kinase (AMPK) and SIRT1. Our findings indicated that the anti-inflammation and anti-apoptosis effects of the combination therapy may be related to activation of AMPK/SIRT1 signaling pathway.

Keywords:  apoptosis; atorvastatin; diabetic cardiomyopathy; inflammation; metformin; oxidative stress

DOI:  https://doi.org/10.3389/fcell.2021.634900
J Cell Mol Med. 2021 Mar 16.

Cardiomyocyte protective effects of thyroid hormone during hypoxia/reoxygenation injury through activating of IGF-1-mediated PI3K/Akt signalling.

Bin Zeng, Lei Liu, Xiaoting Liao, Caixia Zhang.

  Ischaemia/reperfusion (I/R) injury is a common clinical condition that results in apoptosis and oxidative stress injury. Thyroid hormone was previously reported to elicit cardiac myocyte hypertrophy and promote cardiac function after cardiac injury. We used an in vivo mouse model of I/R injury and in vitro primary cardiomyocyte culture assays to investigate the effects of thyroid hormone on cardiomyocytes during hypoxia/reoxygenation (H/R) injury. The results showed that T3 pretreatment in vivo significantly improved left ventricular function after I/R injury. In vitro, T3 pretreatment decreased cell apoptosis rate, inhibited caspase-3 activity and decreased the Bax/Bcl-2 ration induced by H/R injury. T3 pretreatment significantly attenuated the loss of mitochondrial membrane potential. Furthermore, it was observed that T3 diminished the expression of NCX1 protein and decreased SERCA2a protein expression in H/R-induced cardiomyocytes, and T3 prevented intracellular Ca2+ increase during H/R injury. Also, T3 increased the expression of IGF-1, and PI3K/Akt signalling in cardiomyocytes under H/R-induced injury, and that the protective effect of T3 against H/R-induced injury was blocked by the PI3K inhibitor LY294002. IGF-1 receptor (IGF-1R) inhibitor GSK1904529A significantly inhibited the expression of IGF-1R and PI3K/Akt signalling. In summary, T3 pretreatment protects cardiomyocytes against H/R-induced injury by activating the IGF-1-mediated PI3K/Akt signalling pathway.

Keywords:  Akt signalling pathway; Ca2+ homeostasis; PI3K; apoptosis; mitochondrial membrane potential; triiodothyronine

DOI:  https://doi.org/10.1111/jcmm.16389
Free Radic Biol Med. 2021 Mar 11. pii: S0891-5849(21)00141-6. [Epub ahead of print]

Mitochondrial ROS and mitochondria-targeted antioxidants in the aged heart.

Diana Bou-Teen, Nina Kaludercic, David Weissman, Belma Turan, Christoph Maack, Fabio Di Lisa, Marisol Ruiz-Meana.

  Excessive mitochondrial ROS production has been causally linked to the pathophysiology of aging in the heart and other organs, and plays a deleterious role in several age-related cardiac pathologies, including myocardial ischemia-reperfusion injury and heart failure, the two worldwide leading causes of death and disability in the elderly. However, ROS generation is also a fundamental mitochondrial function that orchestrates several signaling pathways, some of them exerting cardioprotective effects. In cardiac myocytes, mitochondria are particularly abundant and are specialized in subcellular populations, in part determined by their relationships with other organelles and their cyclic calcium handling activity necessary for adequate myocardial contraction/relaxation and redox balance. Depending on their subcellular location, mitochondria can themselves be differentially targeted by ROS and display distinct age-dependent functional decline. Thus, precise mitochondria-targeted therapies aimed at counteracting unregulated ROS production are expected to have therapeutic benefits in certain aging-related heart conditions. However, for an adequate design of such therapies, it is necessary to unravel the complex and dynamic interactions between mitochondria and other cellular processes.

Keywords:  AGEs; Aging; cardiomyocytes; cardioprotection; sarcoplasmic reticulum

DOI:  https://doi.org/10.1016/j.freeradbiomed.2021.02.043
Stem Cell Res Ther. 2021 Mar 18. 12(1): 190

GATA-targeted compounds modulate cardiac subtype cell differentiation in dual reporter stem cell line.

Mika J Välimäki, Robert S Leigh, Sini M Kinnunen, Alexander R March, Ana Hernández de Sande, Matias Kinnunen, Markku Varjosalo, Merja Heinäniemi, Bogac L Kaynak, Heikki Ruskoaho.

  BACKGROUND: Pharmacological modulation of cell fate decisions and developmental gene regulatory networks holds promise for the treatment of heart failure. Compounds that target tissue-specific transcription factors could overcome non-specific effects of small molecules and lead to the regeneration of heart muscle following myocardial infarction. Due to cellular heterogeneity in the heart, the activation of gene programs representing specific atrial and ventricular cardiomyocyte subtypes would be highly desirable. Chemical compounds that modulate atrial and ventricular cell fate could be used to improve subtype-specific differentiation of endogenous or exogenously delivered progenitor cells in order to promote cardiac regeneration.METHODS: Transcription factor GATA4-targeted compounds that have previously shown in vivo efficacy in cardiac injury models were tested for stage-specific activation of atrial and ventricular reporter genes in differentiating pluripotent stem cells using a dual reporter assay. Chemically induced gene expression changes were characterized by qRT-PCR, global run-on sequencing (GRO-seq) and immunoblotting, and the network of cooperative proteins of GATA4 and NKX2-5 were further explored by the examination of the GATA4 and NKX2-5 interactome by BioID. Reporter gene assays were conducted to examine combinatorial effects of GATA-targeted compounds and bromodomain and extraterminal domain (BET) inhibition on chamber-specific gene expression.
RESULTS: GATA4-targeted compounds 3i-1000 and 3i-1103 were identified as differential modulators of atrial and ventricular gene expression. More detailed structure-function analysis revealed a distinct subclass of GATA4/NKX2-5 inhibitory compounds with an acetyl lysine-like domain that contributed to ventricular cells (%Myl2-eGFP+). Additionally, BioID analysis indicated broad interaction between GATA4 and BET family of proteins, such as BRD4. This indicated the involvement of epigenetic modulators in the regulation of GATA-dependent transcription. In this line, reporter gene assays with combinatorial treatment of 3i-1000 and the BET bromodomain inhibitor (+)-JQ1 demonstrated the cooperative role of GATA4 and BRD4 in the modulation of chamber-specific cardiac gene expression.
CONCLUSIONS: Collectively, these results indicate the potential for therapeutic alteration of cell fate decisions and pathological gene regulatory networks by GATA4-targeted compounds modulating chamber-specific transcriptional programs in multipotent cardiac progenitor cells and cardiomyocytes. The compound scaffolds described within this study could be used to develop regenerative strategies for myocardial regeneration.

Keywords:  Atrial cardiomyocyte; Cardiomyocyte subtype; GATA4; Heart regeneration; NKX2-5; Stem cells; Ventricular cardiomyocyte

DOI:  https://doi.org/10.1186/s13287-021-02259-z
Redox Biol. 2021 Mar 04. pii: S2213-2317(21)00077-X. [Epub ahead of print]41 101929

Identification of a CTRP9 C-Terminal polypeptide capable of enhancing bone-derived mesenchymal stem cell cardioprotection through promoting angiogenic exosome production.

Demin Liu, Guoqiang Gu, Lu Gan, Wenjun Yan, Zhen Zhang, Peng Yao, Di Zhu, Wayne Bond Lau, Dina Xie, Sisi Wu, Zhijun Meng, Jumpei Tsukuda, Theodore Christopher, Bernard Lopez, Jianli Zhao, Erhe Gao, Walter Koch, Xin-Liang Ma, Yajing Wang.

  BACKGROUND: Mesenchymal stem cell therapy improves ischemic heart failure via incompletely understood mechanisms. C1q-TNFα related protein-9 (CTRP9) is a novel anti-oxidative cardiokine capable of improving the local microenvironment and cell survival by its c-terminal active globular domain (gCTRP9). The current study attempted to: 1) identify active gCTRP9 c-terminal polypeptides with stem cell protective function; 2) determine whether a lead polypeptide may enable/enhance cortical bone-derived mesenchymal stem cell (CBSC) cardioprotection against post-myocardial infarction (post-MI) remodeling; and 3) define the responsible underlying cellular/molecular mechanisms.METHODS AND RESULTS: Utilizing I-TASSER structure prediction and 3-D active site modeling, we cloned and purified 3 gCTRP9 fragments (CTRP9-237, CTRP9-277, and CTRP9-281). Their activation of cell salvage kinase was compared against gCTRP9. Among the three fragments, CTRP9-281 (a 45 residue-containing polypeptide) exerted comparable or greater ERK1/2 activation compared to gCTRP9. Treatment with CTRP9-281 or gCTRP9 significantly increased CBSC proliferation and migration, and attenuated oxidative stress-induced CBSC apoptosis. CTRP9-281 and gCTRP9 comparably upregulated SOD2 and SOD3 expression. However, CTRP9-281, not gCTRP9, upregulated FGF2 and VEGFA expression/secretion in an ERK1/2 dependent manner. Administration of gCTRP9 or CTRP9-281 alone attenuated post-MI cardiac dysfunction and improved CBSC retention in the infarcted heart in similar fashion. However, CTRP9-281 exerted greater synergistic effect with CBSC than gCTRP9 related to pro-angiogenic, anti-fibrotic, and anti-remodeling effects. Mechanistically, CTRP9-281 significantly increased SOD2-rich and VEGFA-rich exosome production by CBSC. Exosomes from CTRP9-281 treated CBSC significantly attenuated oxidative stress-induced cardiomyocyte apoptosis in vitro. An exosome generation inhibitor attenuated CTRP9-281 enhancement of CBSC cardioprotection in vivo.
CONCLUSION: We identified a CTRP9 polypeptide that upregulates SOD2/SOD3 expression and improves CBSC survival/retention, similar to gCTRP9. Moreover, CTRP9-281 stimulates VEGFA-rich exosome production by CBSC, exerting superior pro-angiogenic, anti-fibrotic, and cardioprotective actions.

Keywords:  Cardiokine; Cell therapy; Exosome; Pathological cardiac remodeling

DOI:  https://doi.org/10.1016/j.redox.2021.101929
Sci Rep. 2021 Mar 18. 11(1): 6293

Regulation of cardiomyocyte DNA damage and cell death by the type 2A protein phosphatase regulatory protein alpha4.

Jonathan Cowan, Michael R Longman, Andrew K Snabaitis.

The type 2A protein phosphatase regulatory protein alpha4 (α4) constitutes an anti-apoptotic protein in non-cardiac tissue, however it's anti-apoptotic properties in the heart are poorly defined. To this end, we knocked down α4 protein expression (α4 KD) using siRNA in cultured H9c2 cardiomyocytes and confirmed the lack of DNA damage/cell death by TUNEL staining and MTT assay. However, α4 KD did increase the phosphorylation of p53 and ATM/ATR substrates, decreased the expression of poly ADP-ribose polymerase and associated fragments. Expression of anti-apoptotic proteins Bcl-2 and Bcl-xL was reduced, whereas expression of pro-apoptotic BAX protein did not change. Alpha4 KD reduced basal H2AX Ser139 phosphorylation, whereas adenoviral-mediated re-expression of α4 protein following α4 KD, restored basal H2AX phosphorylation at Ser139. The sensitivity of H9c2 cardiomyocytes to doxorubicin-induced DNA damage and cytotoxicity was augmented by α4 KD. Adenoviral-mediated overexpression of α4 protein in ARVM increased PP2AC expression and augmented H2AX Ser139 phosphorylation in response to doxorubicin. Furthermore, pressure overload-induced heart failure was associated with reduced α4 protein expression, increased ATM/ATR protein kinase activity, increased H2AX expression and Ser139 phosphorylation. Hence, this study describes the significance of altered α4 protein expression in the regulation of DNA damage, cardiomyocyte cell death and heart failure.

DOI: https://doi.org/10.1038/s41598-021-85616-5
Basic Res Cardiol. 2021 Mar 17. 116(1): 18

Cardiomyocyte depolarization triggers NOS-dependent NO transient after calcium release, reducing the subsequent calcium transient.

Matias Mosqueira, Roland Konietzny, Carolin Andresen, Chao Wang, Rainer H A Fink.

  Cardiac excitation-contraction coupling and metabolic and signaling activities are centrally modulated by nitric oxide (NO), which is produced by one of three NO synthases (NOSs). Despite the significant role of NO in cardiac Ca2+ homeostasis regulation under different pathophysiological conditions, such as Duchenne muscular dystrophy (DMD), no precise method describes the production, source or effect of NO through two NO signaling pathways: soluble guanylate cyclase-protein kinase G (NO-sGC-PKG) and S-nitrosylation (SNO). Using a novel strategy involving isolated murine cardiomyocytes loaded with a copper-based dye highly specific for NO, we observed a single transient NO production signal after each electrical stimulation event. The NO transient signal started 67.5 ms after the beginning of Rhod-2 Ca2+ transient signal and lasted for approximately 430 ms. Specific NOS isoform blockers or NO scavengers significantly inhibited the NO transient, suggesting that wild-type (WT) cardiomyocytes produce nNOS-dependent NO transients. Conversely, NO transient in mdx cardiomyocyte, a mouse model of DMD, was dependent on inducible NOS (iNOS) and endothelial (eNOS). In a consecutive stimulation protocol, the nNOS-dependent NO transient in WT cardiomyocytes significantly reduced the next Ca2+ transient via NO-sGC-PKG. In mdx cardiomyocytes, this inhibitory effect was iNOS- and eNOS-dependent and occurred through the SNO pathway. Basal NO production was nNOS- and iNOS-dependent in WT cardiomyocytes and eNOS- and iNOS-dependent in mdx cardiomyocytes. These results showed cardiomyocyte produces NO isoform-dependent transients upon membrane depolarization at the millisecond time scale activating a specific signaling pathway to negatively modulate the subsequent Ca2+ transient.

Keywords:  Calcium transient; Cardiomyocyte; Duchenne muscular dystrophy; Fluo-4; MDX; NO-ON; Nitric oxide; Rhod-2

DOI:  https://doi.org/10.1007/s00395-021-00860-0
Basic Res Cardiol. 2021 Mar 19. 116(1): 19

miR-106a-363 cluster in extracellular vesicles promotes endogenous myocardial repair via Notch3 pathway in ischemic heart injury.

Ji-Hye Jung, Gentaro Ikeda, Yuko Tada, Daniel von Bornstädt, Michelle R Santoso, Christine Wahlquist, Siyeon Rhee, Young-Jun Jeon, Anthony C Yu, Connor G O'brien, Kristy Red-Horse, Eric A Appel, Mark Mercola, Joseph Woo, Phillip C Yang.

  Endogenous capability of the post-mitotic human heart holds great promise to restore the injured myocardium. Recent evidence indicates that the extracellular vesicles (EVs) regulate cardiac homeostasis and regeneration. Here, we investigated the molecular mechanism of EVs for self-repair. We isolated EVs from human iPSC-derived cardiomyocytes (iCMs), which were exposed to hypoxic (hEVs) and normoxic conditions (nEVs), and examined their roles in in vitro and in vivo models of cardiac injury. hEV treatment significantly improved the viability of hypoxic iCMs in vitro and cardiac function of severely injured murine myocardium in vivo. Microarray analysis of the EVs revealed significantly enriched expression of the miR-106a-363 cluster (miR cluster) in hEVs vs. nEVs. This miR cluster preserved survival and contractility of hypoxia-injured iCMs and maintained murine left-ventricular (LV) chamber size, improved LV ejection fraction, and reduced myocardial fibrosis of the injured myocardium. RNA-Seq analysis identified Jag1-Notch3-Hes1 as a target intracellular pathway of the miR cluster. Moreover, the study found that the cell cycle activator and cytokinesis genes were significantly up-regulated in the iCMs treated with miR cluster and Notch3 siRNA. Together, these results suggested that the miR cluster in the EVs stimulated cardiomyocyte cell cycle re-entry by repressing Notch3 to induce cell proliferation and augment myocardial self-repair. The miR cluster may represent an effective therapeutic approach for ischemic cardiomyopathy.

Keywords:  Cell cycle re-entry; EVs; Endogenous cardiac repair mechanism; IPSCs; MiRNAs; Myocardial Infarction

DOI:  https://doi.org/10.1007/s00395-021-00858-8
JCI Insight. 2021 Mar 16. pii: 137593. [Epub ahead of print]

Cardiac retinoic acid levels decline in heart failure.

Ni Yang, Lauren Parker, Jianshi Yu, Jace W Jones, Ting Liu, Kyriakos N Papanicolaou, C Conover Talbot, Kenneth B Margulies, Brian O'Rourke, Maureen Kane, D Brian Foster.

  Though low circulating levels of the vitamin A metabolite, all-trans retinoic acid (ATRA), are associated with increased risk of cardiovascular events and all-cause mortality, few studies have addressed whether cardiac retinoid levels are altered in the failing heart. Here, we show that proteomic analyses of human and guinea pig heart failure (HF) are consistent a decline in resident cardiac ATRA. Quantitation of the retinoids in ventricular myocardium by mass spectrometry reveals 32 and 39% ATRA decreases in guinea pig HF and in patients with idiopathic dilated cardiomyopathy (IDCM), respectively, despite ample reserves of cardiac vitamin A. ATRA (2mg/kg/day) is sufficient to mitigate cardiac remodeling and prevent functional decline in guinea pig HF. Though cardiac ATRA declines in both guinea pig HF human IDCM, levels certain retinoid metabolic enzymes diverge. Specifically, high expression of the ATRA-catabolizing enzyme, CYP26A1, in human IDCM could dampen prospects for an ATRA-based therapy. Pertinently, a pan-CYP26 inhibitor, talarozole, abrogates the impact of phenylephrine on ATRA decline and hypertrophy in neonatal rat ventricular myocytes. Taken together, we submit that low cardiac ATRA attenuates the expression of critical ATRA-dependent gene programs in HF and that strategies to normalize ATRA metabolism, like CYP26 inhibition, may have therapeutic potential.

Keywords:  Cardiology; Heart failure

DOI:  https://doi.org/10.1172/jci.insight.137593
Cell Death Discov. 2021 Mar 15. 7(1): 50

NLRP3-mediated pyroptosis aggravates pressure overload-induced cardiac hypertrophy, fibrosis, and dysfunction in mice: cardioprotective role of irisin.

Rongchuan Yue, Zaiyong Zheng, Yu Luo, Xiaobo Wang, Mingming Lv, Dan Qin, Qingqing Tan, Yulong Zhang, Tao Wang, Houxiang Hu.

The exact mechanism of myocardial hypertrophy has not been completely elucidated. NOD-like receptor protein 3 (NLRP3) and the pyroptotic cascade play a critical role in cardiac hypertrophy and inflammation. The myokine irisin can inhibit NLRP3 activation, although its exact mechanism of action is unknown. In this study, we induced cardiac hypertrophy in a mouse model via aortic constriction (TAC) to further explore the pathological role of NLRP3 inflammasome-mediated pyroptosis and the potential therapeutic effects of irisin. Cardiac hypertrophy significantly increased the percentage of apoptotic cells and upregulated IL-1β, cleaved caspase-1, and GSDMD-N that lie downstream of the NLRP3 inflammasome. Subsequently, irisin was co-administered to the TAC mice or angiotensin II (Ang-II)-treated cardiomyocytes to observe whether it could attenuate pyroptosis and cardiac hypertrophy. We established a direct association between pyroptosis and cardiac hypertrophy and found that pharmacological or genetic inhibition of NLRP3 attenuated cardiac hypertrophy. Furthermore, ectopic overexpression of NLRP3 abrogated the cardioprotective effects of irisin. To summarize, pyroptosis is a pathological factor in cardiac hypertrophy, and irisin is a promising therapeutic agent that inhibits NLRP3-mediated pyroptosis of cardiomyocytes.

DOI: https://doi.org/10.1038/s41420-021-00434-y
Circulation. 2021 Mar 17.

Single Cell RNA-Sequencing Uncovers Paracrine Functions of the Epicardial-Derived Cells in Arrhythmogenic Cardiomyopathy.

Ping Yuan, Sirisha M Cheedipudi, Leila Rouhi, Siyang Fan, Lukas Simon, Zhongming Zhao, Kui Hong, Priyatansh Gurha, Ali J Marian.

  Background: Arrhythmogenic cardiomyopathy (ACM) manifests with sudden death, arrhythmias, heart failure, apoptosis, and myocardial fibro-adipogenesis. The phenotype typically starts at the epicardium and advances transmurally. Mutations in genes encoding desmosome proteins, including DSP (desmoplakin), are major causes of ACM. Methods: To delineate contributions of the epicardium to the pathogenesis of ACM, the Dsp allele was conditionally deleted in the epicardial cells in mice upon expression of tamoxifen-inducible Cre from the Wt1 locus. Wild type (WT) and Wt1-CreERT2:DspW/F were crossed to Rosa26mT/mG (R26mT/mG) dual reporter mice to tag the epicardial-derived cells (EDCs) with the EGFP reporter protein. Tagged EDCs from adult Wt1-CreERT2:R26mT/mG and Wt1-CreERT2: R26mT/mG:DspW/F mouse hearts were isolated by FACS and sequenced by single cell RNA-sequencing (scRNA-Seq). Results: WT1 expression was progressively restricted postnatally and was exclusive to the epicardium by postnatal day 21. Expression of Dsp was reduced in the epicardial cells but not in cardiac myocytes in the Wt1-CreERT2:DspW/F mice. The Wt1-CreERT2:DspW/F mice exhibited premature death, cardiac dysfunction, arrhythmias, myocardial fibro-adipogenesis, and apoptosis. ScRNA-Seq of ~ 18,000 EGFP-tagged EDCs identified genotype-independent clusters of endothelial cells (ECs), fibroblasts, epithelial cells, and a very small cluster of cardiac myocytes, which were confirmed upon co-immunofluorescence staining of the myocardial sections. Differentially expressed genes (DEGs) between the paired clusters in the two genotypes predicted activation of the inflammatory and mitotic pathways, including the TGFβ1 and fibroblast growth factors (FGFs), in the epicardial-derived fibroblast and epithelial clusters but their suppression in the EC cluster. The findings were corroborated by analysis of gene expression in the pooled RNA-Seq data, which identified predominant dysregulation of genes involved in epithelial-mesenchymal transition (EMT), and dysregulation of 146 genes encoding the secreted proteins (secretome), including genes in the TGFβ1 pathway. Activation of the TGFβ1 and its co-localization with fibrosis in the Wt1-CreERT2:R26mT/mG:DspW/F mouse heart was validated by complementary methods. Conclusions: Epicardial-derived cardiac fibroblasts and epithelial cells express paracrine factors, including TGFβ1 and FGFs, which mediate EMT, and contribute to the pathogenesis of myocardial fibrosis, apoptosis, arrhythmias, and cardiac dysfunction in a mouse model of ACM. The findings uncover contributions of the EDCs to the pathogenesis of ACM.

Keywords:  Paracrine factors; single cell RNA sequencing

DOI:  https://doi.org/10.1161/CIRCULATIONAHA.120.052928
Free Radic Biol Med. 2021 Mar 16. pii: S0891-5849(21)00165-9. [Epub ahead of print]

Regulation of Nrf2 signaling pathway in heart failure: Role of extracellular vesicles and non-coding RNAs.

Changhai Tian, Lie Gao, Irving H Zucker.

  The balance between pro- and antioxidant molecules has been established as an important driving force in the pathogenesis of cardiovascular disease. Chronic heart failure is associated with oxidative stress in the myocardium and globally. Redox balance in the heart and brain is controlled, in part, by antioxidant proteins regulated by the transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which is reduced in the heart failure state. Nrf2 can, in turn, be regulated by a variety of mechanisms including circulating microRNAs (miRNAs) encapsulated in extracellular vesicles (EVs) derived from multiple cell types in the heart. Here, we review the role of the Nrf2 and antioxidant enzyme signaling pathway in mediating redox balance in the myocardium and the brain in the heart failure state. This review focuses on Nrf2 and antioxidant protein regulation in the heart and brain by miRNA-enriched EVs in the setting of heart failure. We discuss EV-mediated intra- and inter-organ communications especially, communication between the heart and brain via an EV pathway that mediates cardiac function and sympatho-excitation in heart failure. Importantly, we speculate how engineered EVs with specific miRNAs or antagomirs may be used in a therapeutic manner in heart failure.

Keywords:  Nrf2; antioxidant enzymes; heart failure; microRNA; microvesicles

DOI:  https://doi.org/10.1016/j.freeradbiomed.2021.03.013
Cell Signal. 2021 Mar 12. pii: S0898-6568(21)00066-8. [Epub ahead of print] 109978

FoxO1 is required for high glucose-dependent cardiac fibroblasts into myofibroblast phenoconversion.

Raúl Vivar, Renatto Anfossi, Claudio Humeres, Mabel Catalán, Christopher Reyes, Simone Cárdenas, Alejandra Contreras, Pablo Aránguiz, Fabiola González, Guillermo Diaz-Araya.

  In the normal heart, cardiac fibroblasts (CFs) maintain extracellular matrix (ECM) homeostasis, whereas in pathological conditions, such as diabetes mellitus (DM), CFs converse into cardiac myofibroblasts (CMFs) and this CFs phenoconversion increase the synthesis and secretion of ECM proteins, promoting cardiac fibrosis and heart dysfunction. High glucose (HG) conditions increase TGF-β1 expression and FoxO1 activity, whereas FoxO1 is crucial to CFs phenoconversion induced by TGF-β1. In addition, FoxO1 increases CTGF expression, whereas CTGF plays an active role in the fibrotic process induced by hyperglycemia. However, the role of FoxO1 and CTGF in CFs phenoconversion induced by HG is not clear. In this study, we investigated the effects of FoxO1 pharmacological inhibition on CFs phenoconversion in both in vitro and ex vivo models of DM. Our results demonstrate that HG induces CFs phenoconversion and FoxO1 activation. Moreover, AS1842856, a pharmacological inhibitor of FoxO1 activity, prevents CFs phenoconversion and CTGF expression increase induced by HG, whereas these results were corroborated by FoxO1 silencing. Additionally, K252a, a pharmacological blocker of CTGF receptor, prevents HG-induced CFs phenoconversion, which was corroborated with CTGF expression knockdown. Furthermore, through CFs isolation from heart of diabetic rats, we showed that hyperglycemia induces FoxO1 activation, the increase of CTGF expression and CFs phenoconversion, whereas the FoxO1 activity inhibition reverses the effects induced by hyperglycemia on CFs. Altogether, our results demonstrate that FoxO1 and CTGF are necessary for CFs phenoconversion induced by HG and suggest that both proteins are likely to become a potential targeted drug for fibrotic response induced by hyperglycemic conditions.

Keywords:  CFs phenoconversion; CTGF; Cardiac fibroblast; Cardiac fibrosis; Diabetes mellitus; FoxO1; High glucose

DOI:  https://doi.org/10.1016/j.cellsig.2021.109978
PLoS One. 2021 ;16(3): e0245571

Human induced pluripotent stem cell-derived three-dimensional cardiomyocyte tissues ameliorate the rat ischemic myocardium by remodeling the extracellular matrix and cardiac protein phenotype.

Junya Yokoyama, Shigeru Miyagawa, Takami Akagi, Mitsuru Akashi, Yoshiki Sawa.

The extracellular matrix (ECM) plays a key role in the viability and survival of implanted human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). We hypothesized that coating of three-dimensional (3D) cardiac tissue-derived hiPSC-CMs with the ECM protein fibronectin (FN) would improve the survival of transplanted cells in the heart and improve heart function in a rat model of ischemic heart failure. To test this hypothesis, we first explored the tolerance of FN-coated hiPSC-CMs to hypoxia in an in vitro study. For in vivo assessments, we constructed 3D-hiPSC cardiac tissues (3D-hiPSC-CTs) using a layer-by-layer technique, and then the cells were implanted in the hearts of a myocardial infarction rat model (3D-hiPSC-CTs, n = 10; sham surgery control group (without implant), n = 10). Heart function and histology were analyzed 4 weeks after transplantation. In the in vitro assessment, cell viability and lactate dehydrogenase assays showed that FN-coated hiPSC-CMs had improved tolerance to hypoxia compared with the control cells. In vivo, the left ventricular ejection fraction of hearts implanted with 3D-hiPSC-CT was significantly better than that of the sham control hearts. Histological analysis showed clear expression of collagen type IV and plasma membrane markers such as desmin and dystrophin in vivo after implantation of 3D-hiPSC-CT, which were not detected in 3D-hiPSC-CMs in vitro. Overall, these results indicated that FN-coated 3D-hiPSC-CT could improve distressed heart function in a rat myocardial infarction model with a well-expressed cytoskeletal or basement membrane matrix. Therefore, FN-coated 3D-hiPSC-CT may serve as a promising replacement for heart transplantation and left ventricular assist devices and has the potential to improve survivability and therapeutic efficacy in cases of ischemic heart disease.

DOI: https://doi.org/10.1371/journal.pone.0245571
Mol Ther Nucleic Acids. 2021 Mar 05. 23 1304-1322

Exosomal LINC00174 derived from vascular endothelial cells attenuates myocardial I/R injury via p53-mediated autophagy and apoptosis.

Qiang Su, Xiang-Wei Lv, Yu-Li Xu, Ru-Ping Cai, Ri-Xin Dai, Xi-Heng Yang, Wei-Kun Zhao, Bing-Hui Kong.

  In this study, we aim to investigate the regulation of specific long non-coding RNAs (lncRNAs) on the progression of ischemia/reperfusion (I/R) injury. We identified and characterized the exosomes derived from mouse primary aortic endothelial cells. Subsequently, we found that these exosomes expressed typical exosomal markers and high levels of LINC00174, which significantly ameliorated I/R-induced myocardial damage and suppressed the apoptosis, vacuolation, and autophagy of myocardial cells. Mechanistic approaches revealed that LINC00174 directly interacted with SRSF1 to suppress the expression of p53, thus restraining the transcription of myocardin and repressing the activation of the Akt/AMPK pathway that was crucial for autophagy initiation in I/R-induced myocardial damage. Moreover, this molecular mechanism was verified by in vivo study. In summary, exosomal LINC00174 generated from vascular endothelial cells repressed p53-mediated autophagy and apoptosis to mitigate I/R-induced myocardial damage, suggesting that targeting LINC00174 may be a novel strategy to treat I/R-induced myocardial infarction.

Keywords:  LINC00174; apoptosis; autophagy; ischemia/reperfusion injury; p53; vascular endothelial cells

DOI:  https://doi.org/10.1016/j.omtn.2021.02.005
Nat Commun. 2021 03 16. 12(1): 1684

Xbp1s-FoxO1 axis governs lipid accumulation and contractile performance in heart failure with preserved ejection fraction.

Gabriele G Schiattarella, Francisco Altamirano, Soo Young Kim, Dan Tong, Anwarul Ferdous, Hande Piristine, Subhajit Dasgupta, Xuliang Wang, Kristin M French, Elisa Villalobos, Stephen B Spurgin, Maayan Waldman, Nan Jiang, Herman I May, Theodore M Hill, Yuxuan Luo, Heesoo Yoo, Vlad G Zaha, Sergio Lavandero, Thomas G Gillette, Joseph A Hill.

Heart failure with preserved ejection fraction (HFpEF) is now the dominant form of heart failure and one for which no efficacious therapies exist. Obesity and lipid mishandling greatly contribute to HFpEF. However, molecular mechanism(s) governing metabolic alterations and perturbations in lipid homeostasis in HFpEF are largely unknown. Here, we report that cardiomyocyte steatosis in HFpEF is coupled with increases in the activity of the transcription factor FoxO1 (Forkhead box protein O1). FoxO1 depletion, as well as over-expression of the Xbp1s (spliced form of the X-box-binding protein 1) arm of the UPR (unfolded protein response) in cardiomyocytes each ameliorates the HFpEF phenotype in mice and reduces myocardial lipid accumulation. Mechanistically, forced expression of Xbp1s in cardiomyocytes triggers ubiquitination and proteasomal degradation of FoxO1 which occurs, in large part, through activation of the E3 ubiquitin ligase STUB1 (STIP1 homology and U-box-containing protein 1) a novel and direct transcriptional target of Xbp1s. Our findings uncover the Xbp1s-FoxO1 axis as a pivotal mechanism in the pathogenesis of cardiometabolic HFpEF and unveil previously unrecognized mechanisms whereby the UPR governs metabolic alterations in cardiomyocytes.

DOI: https://doi.org/10.1038/s41467-021-21931-9
Cardiovasc Res. 2021 Mar 16. pii: cvab084. [Epub ahead of print]

Remodelling of adult cardiac tissue subjected to physiological and pathological mechanical load in vitro.

Fotios G Pitoulis, Raquel Nunez-Toldra, Ke Xiao, Worrapong Kit-Anan, Saskia Mitzka, Richard J Jabbour, Sian E Harding, Filippo Perbellini, Thomas Thum, Pieter P de Tombe, Cesare M Terracciano.

  AIMS: Cardiac remodelling is the process by which the heart adapts to its environment. Mechanical load is a major driver of remodelling. Cardiac tissue culture has been frequently employed for in vitro studies of load-induced remodelling; however, current in vitro protocols (e.g. cyclic stretch, isometric load, auxotonic load) are oversimplified and do not accurately capture the dynamic sequence of mechanical conformational changes experienced by the heart in vivo. This limits translational scope and relevance of findings.METHODS AND RESULTS: We developed a novel methodology to study chronic load in vitro. We first developed a bioreactor that can recreate the electromechanical events of in vivo pressure-volume loops as in vitro force-length loops. We then used the bioreactor to culture rat living myocardial slices (LMS) for 3 days. The bioreactor operated on the basis of a 3-Element Windkessel circulatory model enabling tissue mechanical loading based on physiologically relevant parameters of afterload and preload. LMS were continuously stretched/relaxed during culture simulating conditions of physiological load (normal preload & afterload), pressure-overload (normal preload & high afterload), or volume-overload (high preload & normal afterload). At the end of culture, functional, structural, and molecular assays were performed to determine load-induced remodelling.Both pressure- and volume-overloaded LMS showed significantly decreased contractility that was more pronounced in the latter compared with physiological load p < 0.0001). Overloaded groups also showed cardiomyocyte hypertrophy; RNAseq identified shared and unique genes expressed in each overload group. The PI3K-Akt pathway was dysregulated in volume-overload while inflammatory pathways were mostly associated with remodelling in pressure-overloaded LMS.
CONCLUSION: We have developed a proof-of-concept platform and methodology to recreate remodelling under pathophysiological load in vitro. We show that LMS cultured in our bioreactor remodel as a function of the type of mechanical load applied to them.

Keywords:   in vitro cardiac tissue culture; Myocardial remodelling; mechanical load; myocardial slices; pressure overload; volume overload

DOI:  https://doi.org/10.1093/cvr/cvab084
Free Radic Biol Med. 2021 Mar 15. pii: S0891-5849(21)00159-3. [Epub ahead of print]

Macrophage p47phox Regulates Pressure Overload-Induced Left Ventricular Remodelling by Modulating IL-4/STAT6/PPARγ Signaling.

Sukka Santosh Reddy, Heena Agarwal, Anant Jaiswal, Kumaravelu Jagavelu, Madhu Dikshit, Manoj Kumar Barthwal.

  NADPH oxidase (Nox) mediates ROS production and contributes to cardiac remodeling. However, macrophage p47phox, a Nox subunit regulating cardiac remodeling, is unclear. We aimed to investigate the role of macrophage p47phox in hypertensive cardiac remodeling. Pressure-overload induced by Angiotensin II (AngII) for two weeks in young adult male p47phox deficient (KO) mice showed aggravated cardiac dysfunction and hypertrophy as indicated from echocardiographic and histological studies in comparison with wild-type littermates (WT). Additionally, LV of AngII-infused KO mice showed augmented interstitial fibrosis, collagen deposition and, myofibroblasts compared to AngII-infused WT mice. Moreover, these changes in AngII-infused KO mice correlated well with the gene analysis of hypertrophic and fibrotic markers. Similar results were also found in the transverse aortic constriction model. Further, AngII-infused KO mice showed elevated circulating immunokines and increased LV leukocytes infiltration and CD206+ macrophages compared to AngII-infused WT mice. Likewise, LV of AngII-infused KO mice showed upregulated mRNA expression of anti-inflammatory/pro-fibrotic M2 macrophage markers (Ym1, Arg-1) compared to AngII-infused WT mice. AngII and IL-4 treated bone marrow-derived macrophages (BMDMs) from KO mice showed upregulated M2 macrophage markers and STAT6 phosphorylation (Y641) compared to AngII and IL-4 treated WT BMDMs. These alterations were at least partly mediated by macrophage as bone marrow transplantation from KO mice into WT mice aggravated cardiac remodelling. Mechanistically, AngII-infused KO mice showed hyperactivated IL-4/STAT6/PPARγ signaling and downregulated SOCS3 expression compared to AngII-infused WT mice. Our studies show that macrophage p47phox limits anti-inflammatory signaling and extracellular matrix remodeling in response to pressure-overload.

Keywords:  Angiotensin II; fibrosis; hypertension; hypertrophy; macrophages; p47(phox)

DOI:  https://doi.org/10.1016/j.freeradbiomed.2021.03.007
Nat Commun. 2021 03 15. 12(1): 1680

Branched-chain α-ketoacids are preferentially reaminated and activate protein synthesis in the heart.

Jacquelyn M Walejko, Bridgette A Christopher, Scott B Crown, Guo-Fang Zhang, Adrian Pickar-Oliver, Takeshi Yoneshiro, Matthew W Foster, Stephani Page, Stephan van Vliet, Olga Ilkayeva, Michael J Muehlbauer, Matthew W Carson, Joseph T Brozinick, Craig D Hammond, Ruth E Gimeno, M Arthur Moseley, Shingo Kajimura, Charles A Gersbach, Christopher B Newgard, Phillip J White, Robert W McGarrah.

Branched-chain amino acids (BCAA) and their cognate α-ketoacids (BCKA) are elevated in an array of cardiometabolic diseases. Here we demonstrate that the major metabolic fate of uniformly-13C-labeled α-ketoisovalerate ([U-13C]KIV) in the heart is reamination to valine. Activation of cardiac branched-chain α-ketoacid dehydrogenase (BCKDH) by treatment with the BCKDH kinase inhibitor, BT2, does not impede the strong flux of [U-13C]KIV to valine. Sequestration of BCAA and BCKA away from mitochondrial oxidation is likely due to low levels of expression of the mitochondrial BCAA transporter SLC25A44 in the heart, as its overexpression significantly lowers accumulation of [13C]-labeled valine from [U-13C]KIV. Finally, exposure of perfused hearts to levels of BCKA found in obese rats increases phosphorylation of the translational repressor 4E-BP1 as well as multiple proteins in the MEK-ERK pathway, leading to a doubling of total protein synthesis. These data suggest that elevated BCKA levels found in obesity may contribute to pathologic cardiac hypertrophy via chronic activation of protein synthesis.

DOI: https://doi.org/10.1038/s41467-021-21962-2
Basic Res Cardiol. 2021 Mar 15. 116(1): 17

A DARPin targeting activated Mac-1 is a novel diagnostic tool and potential anti-inflammatory agent in myocarditis, sepsis and myocardial infarction.

Patrick M Siegel, István Bojti, Nicole Bassler, Jessica Holien, Ulrike Flierl, Xiaowei Wang, Philipp Waggershauser, Xavier Tonnar, Christopher Vedecnik, Constanze Lamprecht, Ivana Stankova, Tian Li, Thomas Helbing, Dennis Wolf, Nathaly Anto-Michel, Lucia Sol Mitre, Julia Ehrlich, Lukas Orlean, Ileana Bender, Anne Przewosnik, Maximilian Mauler, Laura Hollederer, Martin Moser, Christoph Bode, Michael W Parker, Karlheinz Peter, Philipp Diehl.

  The monocyte β2-integrin Mac-1 is crucial for leukocyte-endothelium interaction, rendering it an attractive therapeutic target for acute and chronic inflammation. Using phage display, a Designed-Ankyrin-Repeat-Protein (DARPin) was selected as a novel binding protein targeting and blocking the αM I-domain, an activation-specific epitope of Mac-1. This DARPin, named F7, specifically binds to activated Mac-1 on mouse and human monocytes as determined by flow cytometry. Homology modelling and docking studies defined distinct interaction sites which were verified by mutagenesis. Intravital microscopy showed reduced leukocyte-endothelium adhesion in mice treated with this DARPin. Using mouse models of sepsis, myocarditis and ischaemia/reperfusion injury, we demonstrate therapeutic anti-inflammatory effects. Finally, the activated Mac-1-specific DARPin is established as a tool to detect monocyte activation in patients receiving extra-corporeal membrane oxygenation, as well as suffering from sepsis and ST-elevation myocardial infarction. The activated Mac-1-specific DARPin F7 binds preferentially to activated monocytes, detects inflammation in critically ill patients, and inhibits monocyte and neutrophil function as an efficient new anti-inflammatory agent.

Keywords:  DARPin; ECMO; Inflammation; Myocardial infarction; Myocarditis; Sepsis

DOI:  https://doi.org/10.1007/s00395-021-00849-9
Circ Res. 2021 Mar 19. 128(6): 775-801

Cardiac Tissues From Stem Cells: New Routes to Maturation and Cardiac Regeneration.

Giulia Campostrini, Laura M Windt, Berend J van Meer, Milena Bellin, Christine L Mummery.

  The ability of human pluripotent stem cells to form all cells of the body has provided many opportunities to study disease and produce cells that can be used for therapy in regenerative medicine. Even though beating cardiomyocytes were among the first cell types to be differentiated from human pluripotent stem cell, cardiac applications have advanced more slowly than those, for example, for the brain, eye, and pancreas. This is, in part, because simple 2-dimensional human pluripotent stem cell cardiomyocyte cultures appear to need crucial functional cues normally present in the 3-dimensional heart structure. Recent tissue engineering approaches combined with new insights into the dialogue between noncardiomyocytes and cardiomyocytes have addressed and provided solutions to issues such as cardiomyocyte immaturity and inability to recapitulate adult heart values for features like contraction force, electrophysiology, or metabolism. Three-dimensional bioengineered heart tissues are thus poised to contribute significantly to disease modeling, drug discovery, and safety pharmacology, as well as provide new modalities for heart repair. Here, we review the current status of 3-dimensional engineered heart tissues.

Keywords:  cardiac tissue; drug discovery; heart failure; humans; stem cells

DOI:  https://doi.org/10.1161/CIRCRESAHA.121.318183
Food Funct. 2021 Mar 15.

Cardioprotective action of chia (Salvia hispanica L.) in ovariectomized rats fed a high fat diet.

Marcella Duarte Villas Mishima, Luiz Carlos Maia Ladeira, Bárbara Pereira da Silva, Renata Celi Lopes Toledo, Thomás Valente de Oliveira, Neuza Maria Brunoro Costa, Hércia Stampini Duarte Martino.

The reduction in estrogen levels is associated with the increased risk factors for cardiovascular disease development. The present study aimed to evaluate the effect of chia consumption in a standard diet (SD) or high fat diet (HFD) on ovariectomized (OVX) and non-ovariectomized (SHAM) rats, in relation to biometric measurements, oxidative stress, mineral content and ATPase enzymes in the heart. The study was conducted with 80 female Wistar rats, which received a SD or HFD for 18 weeks. During the first 7 weeks, the animals received the SD or HFD. Then, 40 rats were ovariectomized and 40 rats were SHAM operated. After recovery from surgery, the animals were allocated to 8 groups (n = 10) and they received one of the following diets for 8 weeks: SD, SD + chia, HFD and HFD + chia. In the OVX group, HFD increased weight gain, adiposity, cardiac hypertrophy, and nitric oxide (NO) and K concentration and decreased the Na+/K+ATPase activity. In combination with HFD, ovariectomy decreased the catalase activity, Mg, Cu and Zn concentration, total ATPase activity, and Na+/K+ATPase and Mg2 + ATPase activities; this group also presented higher NO, Ca, K, Fe and Mn concentration in the heart. The SHAM group fed chia presented a lower fat content in the heart. In the OVX group fed HFD, chia increased the activity of superoxide dismutase, decreased NO and maintained the content of minerals and ATPase enzymes. Thus, chia improved the biometric parameters of the heart, the antioxidant activity and maintained the content of minerals and ATPase enzymes, showing a cardioprotective action, but without reversing the deleterious effects of ovariectomy.

DOI: https://doi.org/10.1039/d0fo03206a
Sci Rep. 2021 Mar 18. 11(1): 5837

Sparsely methylated mitochondrial cell free DNA released from cardiomyocytes contributes to systemic inflammatory response accompanied by atrial fibrillation.

Masahiro Yamazoe, Tetsuo Sasano, Kensuke Ihara, Kentaro Takahashi, Wakana Nakamura, Naomi Takahashi, Hiroaki Komuro, Satomi Hamada, Tetsushi Furukawa.

Systemic inflammation is assumed to be the consequence and the cause of atrial fibrillation (AF); however, the underlying mechanism remains unclear. We aimed to evaluate the level of cell-free DNA (cfDNA) in patients with AF and AF mimicking models, and to illuminate its impact on inflammation. Peripheral blood was obtained from 54 patients with AF and 104 non-AF controls, and cfDNA was extracted. We extracted total cfDNA from conditioned medium after rapid pacing to HL-1 cells. Nuclear and mitochondrial DNA were separately extracted and fragmented to simulate nuclear-cfDNA (n-cfDNA) and mitochondrial-cfDNA (mt-cfDNA). The AF group showed higher cfDNA concentration than the non-AF group (12.6 [9.0-17.1] vs. 8.1 [5.3-10.8] [ng/mL], p < 0.001). The copy numbers of n-cfDNA and mt-cfDNA were higher in AF groups than in non-AF groups; the difference of mt-cfDNA was particularly apparent (p = 0.011 and p < 0.001, respectively). Administration of total cfDNA and mt-cfDNA to macrophages significantly promoted IL-1β and IL-6 expression through TLR9, whereas n-cfDNA did not. Induction of cytokine expression by methylated mt-cfDNA was lower than that by unmethylated mt-cfDNA. Collectively, AF was associated with an increased cfDNA level, especially mt-cfDNA. Sparsely methylated mt-cfDNA released from cardiomyocytes may be involved in sterile systemic inflammation accompanied by AF.

DOI: https://doi.org/10.1038/s41598-021-85204-7
Nat Commun. 2021 Mar 19. 12(1): 1771

Spatiotemporal single-cell RNA sequencing of developing chicken hearts identifies interplay between cellular differentiation and morphogenesis.

Madhav Mantri, Gaetano J Scuderi, Roozbeh Abedini-Nassab, Michael F Z Wang, David McKellar, Hao Shi, Benjamin Grodner, Jonathan T Butcher, Iwijn De Vlaminck.

Single-cell RNA sequencing is a powerful tool to study developmental biology but does not preserve spatial information about tissue morphology and cellular interactions. Here, we combine single-cell and spatial transcriptomics with algorithms for data integration to study the development of the chicken heart from the early to late four-chambered heart stage. We create a census of the diverse cellular lineages in developing hearts, their spatial organization, and their interactions during development. Spatial mapping of differentiation transitions in cardiac lineages defines transcriptional differences between epithelial and mesenchymal cells within the epicardial lineage. Using spatially resolved expression analysis, we identify anatomically restricted expression programs, including expression of genes implicated in congenital heart disease. Last, we discover a persistent enrichment of the small, secreted peptide, thymosin beta-4, throughout coronary vascular development. Overall, our study identifies an intricate interplay between cellular differentiation and morphogenesis.

DOI: https://doi.org/10.1038/s41467-021-21892-z