Dnmt3a-mediated inhibition of Wnt in cardiac progenitor cells improves differentiation and remote remodeling after infarction

• Text
• PDF

Abstract

Adult cardiac progenitor cells (CPCs) display a low capacity to differentiate into cardiomyocytes in injured hearts, strongly limiting the regenerative capacity of the mammalian myocardium. To identify new mechanisms regulating CPC differentiation, we used primary and clonally expanded Sca-1+ CPCs from murine adult hearts in homotypic culture or coculture with cardiomyocytes. Expression kinetics analysis during homotypic culture differentiation showed downregulation of Wnt target genes concomitant with increased expression of the Wnt antagonist, Wnt inhibitory factor 1 (Wif1), which is necessary to stimulate CPC differentiation. We show that the expression of the Wif1 gene is repressed by DNA methylation and regulated by the de novo DNA methyltransferase Dnmt3a. In addition, miR-29a is upregulated early during CPC differentiation and downregulates Dnmt3a expression, thereby decreasing Wif1 gene methylation and increasing the efficiency of differentiation of Sca-1+ CPCs in vitro. Extending these findings in vivo, transient silencing of Dnmt3a in CPCs subsequently injected in the border zone of infarcted mouse hearts improved CPC differentiation in situ and remote cardiac remodeling. In conclusion, miR-29a and Dnmt3a epigenetically regulate CPC differentiation through Wnt inhibition. Remote effects on cardiac remodeling support paracrine signaling beyond the local injection site, with potential therapeutic interest for cardiac repair.

Authors

Aurelia De Pauw, Emilie Andre, Belaid Sekkali, Caroline Bouzin, Hrag Esfahani, Nicolas Barbier, Axelle Loriot, Charles De Smet, Laetitia Vanhoutte, Stéphane Moniotte, Bernhard Gerber, Vittoria di Mauro, Daniele Catalucci, Olivier Feron, Denise Hilfiker-Kleiner, Jean-Luc Balligand

Myeloid-related protein-14 regulates deep vein thrombosis

• Text
• PDF

Abstract

Using transcriptional profiling of platelets from patients presenting with acute myocardial infarction, we identified myeloid-related protein-14 (MRP-14, also known as S100A9) as an acute myocardial infarction gene and reported that platelet MRP-14 binding to platelet CD36 regulates arterial thrombosis. However, whether MRP-14 plays a role in venous thrombosis is unknown. We subjected WT and Mrp-14–deficient (Mrp-14-/-) mice to experimental models of deep vein thrombosis (DVT) by stasis ligation or partial flow restriction (stenosis) of the inferior vena cava. Thrombus weight in response to stasis ligation or stenosis was reduced significantly in Mrp-14-/- mice compared with WT mice. The adoptive transfer of WT neutrophils or platelets, or the infusion of recombinant MRP-8/14, into Mrp-14-/- mice rescued the venous thrombosis defect in Mrp-14-/- mice, indicating that neutrophil- and platelet-derived MRP-14 directly regulate venous thrombogenesis. Stimulation of neutrophils with MRP-14 induced neutrophil extracellular trap (NET) formation, and NETs were reduced in venous thrombi harvested from Mrp-14-/- mice and in Mrp-14-/- neutrophils stimulated with ionomycin. Given prior evidence that MRP-14 also regulates arterial thrombosis, but not hemostasis (i.e., reduced bleeding risk), MRP-14 appears to be a particularly attractive molecular target for treating thrombotic cardiovascular diseases, including myocardial infarction, stroke, and venous thromboembolism.

Authors

Yunmei Wang, Huiyun Gao, Chase W. Kessinger, Alvin Schmaier, Farouc A. Jaffer, Daniel I. Simon

Insulin supplementation attenuates cancer-induced cardiomyopathy and slows tumor disease progression

• Text
• PDF

Abstract

Advanced cancer induces fundamental changes in metabolism and promotes cardiac atrophy and heart failure. We discovered systemic insulin deficiency in cachectic cancer patients. Similarly, mice with advanced B16F10 melanoma (B16F10-TM) or colon 26 carcinoma (C26-TM) displayed decreased systemic insulin associated with marked cardiac atrophy, metabolic impairment, and function. B16F10 and C26 tumors decrease systemic insulin via high glucose consumption, lowering pancreatic insulin production and producing insulin-degrading enzyme. As tumor cells consume glucose in an insulin-independent manner, they shift glucose away from cardiomyocytes. Since cardiomyocytes in both tumor models remained insulin responsive, low-dose insulin supplementation by subcutaneous implantation of insulin-releasing pellets improved cardiac glucose uptake, atrophy, and function, with no adverse side effects. In addition, by redirecting glucose to the heart in addition to other organs, the systemic insulin treatment lowered glucose usage by the tumor and thereby decreased tumor growth and volume. Insulin corrected the cancer-induced reduction in cardiac Akt activation and the subsequent overactivation of the proteasome and autophagy. Thus, cancer-induced systemic insulin depletion contributes to cardiac wasting and failure and may promote tumor growth. Low-dose insulin supplementation attenuates these processes and may be supportive in cardio-oncologic treatment concepts.

Authors

James T. Thackeray, Stefan Pietzsch, Britta Stapel, Melanie Ricke-Hoch, Chun-Wei Lee, Jens P. Bankstahl, Michaela Scherr, Jörg Heineke, Gesine Scharf, Arash Haghikia, Frank M. Bengel, Denise Hilfiker-Kleiner

Increased de novo ceramide synthesis and accumulation in failing myocardium

• Text
• PDF

Abstract

Abnormal lipid metabolism may contribute to myocardial injury and remodeling. To determine whether accumulation of very long–chain ceramides occurs in human failing myocardium, we analyzed myocardial tissue and serum from patients with severe heart failure (HF) undergoing placement of left ventricular assist devices and controls. Lipidomic analysis revealed increased total and very long–chain ceramides in myocardium and serum of patients with advanced HF. After unloading, these changes showed partial reversibility. Following myocardial infarction (MI), serine palmitoyl transferase (SPT), the rate-limiting enzyme of the de novo pathway of ceramide synthesis, and ceramides were found increased. Blockade of SPT by the specific inhibitor myriocin reduced ceramide accumulation in ischemic cardiomyopathy and decreased C16, C24:1, and C24 ceramides. SPT inhibition also reduced ventricular remodeling, fibrosis, and macrophage content following MI. Further, genetic deletion of the SPTLC2 gene preserved cardiac function following MI. Finally, in vitro studies revealed that changes in ceramide synthesis are linked to hypoxia and inflammation. In conclusion, cardiac ceramides accumulate in the failing myocardium, and increased levels are detectable in circulation. Inhibition of de novo ceramide synthesis reduces cardiac remodeling. Thus, increased de novo ceramide synthesis contributes to progressive pathologic cardiac remodeling and dysfunction.

Authors

Ruiping Ji, Hirokazu Akashi, Konstantinos Drosatos, Xianghai Liao, Hongfeng Jiang, Peter J. Kennel, Danielle L. Brunjes, Estibaliz Castillero, Xiaokan Zhang, Lily Y. Deng, Shunichi Homma, Isaac J. George, Hiroo Takayama, Yoshifumi Naka, Ira J. Goldberg, P. Christian Schulze

Atherogenesis and metabolic dysregulation in LDL receptor–knockout rats

• Text
• PDF

Abstract

Mechanisms of atherogenesis have been studied extensively in genetically engineered mice with disturbed cholesterol metabolism such as those lacking either the LDL receptor (Ldlr) or apolipoprotein E (apoe). Few other animal models of atherosclerosis are available. WT rabbits or rats, even on high-fat or high-cholesterol diets, develop sparse atherosclerotic lesions. We examined the effects of Ldlr deletion on lipoprotein metabolism and atherosclerotic lesion formation in Sprague-Dawley rats. Deletion of Ldlr resulted in the loss of the LDLR protein and caused a significant increase in plasma total cholesterol and triglycerides. On normal chow, Ldlr-KO rats gained more weight and were more glucose intolerant than WT rats. Plasma proprotein convertase subtilisin kexin 9 (PCSK9) and leptin levels were higher and adiponectin levels were lower in KO than WT rats. On the Western diet, the KO rats displayed exaggerated obesity and age-dependent increases in glucose intolerance. No appreciable aortic lesions were observed in KO rats fed normal chow for 64 weeks or Western diet for 16 weeks; however, after 34–52 weeks of Western diet, the KO rats developed exuberant atherosclerotic lesions in the aortic arch and throughout the abdominal aorta. The Ldlr-KO rat may be a useful model for studying obesity, insulin resistance, and early-stage atherosclerosis.

Authors

Srinivas D. Sithu, Marina V. Malovichko, Krista A. Riggs, Nalinie S. Wickramasinghe, Millicent G. Winner, Abhinav Agarwal, Rihab E. Hamed-Berair, Anuradha Kalani, Daniel W. Riggs, Aruni Bhatnagar, Sanjay Srivastava

miR-21 is associated with fibrosis and right ventricular failure

• Text
• PDF

Abstract

Combined pulmonary insufficiency (PI) and stenosis (PS) is a common long-term sequela after repair of many forms of congenital heart disease, causing progressive right ventricular (RV) dilation and failure. Little is known of the mechanisms underlying this combination of preload and afterload stressors. We developed a murine model of PI and PS (PI+PS) to identify clinically relevant pathways and biomarkers of disease progression. Diastolic dysfunction was induced (restrictive RV filling, elevated RV end-diastolic pressures) at 1 month after generation of PI+PS and progressed to systolic dysfunction (decreased RV shortening) by 3 months. RV fibrosis progressed from 1 month (4.4% ± 0.4%) to 3 months (9.2% ± 1%), along with TGF-β signaling and tissue expression of profibrotic miR-21. Although plasma miR-21 was upregulated with diastolic dysfunction, it was downregulated with the onset of systolic dysfunction), correlating with RV fibrosis. Plasma miR-21 in children with PI+PS followed a similar pattern. A model of combined RV volume and pressure overload recapitulates the evolution of RV failure unique to patients with prior RV outflow tract surgery. This progression was characterized by enhanced TGF-β and miR-21 signaling. miR-21 may serve as a plasma biomarker of RV failure, with decreased expression heralding the need for valve replacement.

Authors

Sushma Reddy, Dong-Qing Hu, Mingming Zhao, Eddie Blay Jr., Nefthi Sandeep, Sang-Ging Ong, Gwanghyun Jung, Kristina B. Kooiker, Michael Coronado, Giovanni Fajardo, Daniel Bernstein

RyR₂^R420Q catecholaminergic polymorphic ventricular tachycardia mutation induces bradycardia by disturbing the coupled clock pacemaker mechanism

• Text
• PDF

Abstract

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal genetic arrhythmia that manifests syncope or sudden death in children and young adults under stress conditions. CPVT patients often present bradycardia and sino-atrial node (SAN) dysfunction. However, the mechanism remains unclear. We analyzed SAN function in two CPVT families and in a novel knock-in (KI) mouse model carrying the RyR₂^R420Q mutation. Humans and KI mice presented slower resting heart rate. Accordingly, the rate of spontaneous intracellular Ca²⁺ ([Ca²⁺]_i) transients was slower in KI mouse SAN preparations than in WT, without any significant alteration in the “funny” current (I_f ). The L-type Ca²⁺ current was reduced in KI SAN cells in a [Ca²⁺]_i-dependent way, suggesting that bradycardia was due to disrupted crosstalk between the “voltage” and “Ca²⁺” clock, and the mechanisms of pacemaking was induced by aberrant spontaneous RyR₂- dependent Ca²⁺ release. This finding was consistent with a higher Ca²⁺ leak during diastolic periods produced by long-lasting Ca²⁺ sparks in KI SAN cells. Our results uncover a mechanism for the CPVT-causing RyR₂ N-terminal mutation R420Q, and they highlight the fact that enhancing the Ca²⁺ clock may slow the heart rhythm by disturbing the coupling between Ca²⁺ and voltage clocks.

Authors

Yue Yi Wang, Pietro Mesirca, Elena Marqués-Sulé, Alexandra Zahradnikova Jr., Olivier Villejoubert, Pilar D’Ocon, Cristina Ruiz, Diana Domingo, Esther Zorio, Matteo E. Mangoni, Jean-Pierre Benitah, Ana María Gómez

Steroid metabolome analysis reveals prevalent glucocorticoid excess in primary aldosteronism

• Text
• PDF

Abstract

BACKGROUND. Adrenal aldosterone excess is the most common cause of secondary hypertension and is associated with increased cardiovascular morbidity. However, adverse metabolic risk in primary aldosteronism extends beyond hypertension, with increased rates of insulin resistance, type 2 diabetes, and osteoporosis, which cannot be easily explained by aldosterone excess.

METHODS. We performed mass spectrometry–based analysis of a 24-hour urine steroid metabolome in 174 newly diagnosed patients with primary aldosteronism (103 unilateral adenomas, 71 bilateral adrenal hyperplasias) in comparison to 162 healthy controls, 56 patients with endocrine inactive adrenal adenoma, 104 patients with mild subclinical, and 47 with clinically overt adrenal cortisol excess. We also analyzed the expression of cortisol-producing CYP11B1 and aldosterone-producing CYP11B2 enzymes in adenoma tissue from 57 patients with aldosterone-producing adenoma, employing immunohistochemistry with digital image analysis.

RESULTS. Primary aldosteronism patients had significantly increased cortisol and total glucocorticoid metabolite excretion (all P < 0.001), only exceeded by glucocorticoid output in patients with clinically overt adrenal Cushing syndrome. Several surrogate parameters of metabolic risk correlated significantly with glucocorticoid but not mineralocorticoid output. Intratumoral CYP11B1 expression was significantly associated with the corresponding in vivo glucocorticoid excretion. Unilateral adrenalectomy resolved both mineralocorticoid and glucocorticoid excess. Postoperative evidence of adrenal insufficiency was found in 13 (29%) of 45 consecutively tested patients.

CONCLUSION. Our data indicate that glucocorticoid cosecretion is frequently found in primary aldosteronism and contributes to associated metabolic risk. Mineralocorticoid receptor antagonist therapy alone may not be sufficient to counteract adverse metabolic risk in medically treated patients with primary aldosteronism.

FUNDING. Medical Research Council UK, Wellcome Trust, European Commission.

Authors

Wiebke Arlt, Katharina Lang, Alice J. Sitch, Anna S. Dietz, Yara Rhayem, Irina Bancos, Annette Feuchtinger, Vasileios Chortis, Lorna C. Gilligan, Philippe Ludwig, Anna Riester, Evelyn Asbach, Beverly A. Hughes, Donna M. O’Neil, Martin Bidlingmaier, Jeremy W. Tomlinson, Zaki K. Hassan-Smith, D. Aled Rees, Christian Adolf, Stefanie Hahner, Marcus Quinkler, Tanja Dekkers, Jaap Deinum, Michael Biehl, Brian G. Keevil, Cedric H.L. Shackleton, Jonathan J. Deeks, Axel K. Walch, Felix Beuschlein, Martin Reincke

Point mutations in murine Nkx2-5 phenocopy human congenital heart disease and induce pathogenic Wnt signaling

• Text
• PDF

Abstract

Mutations in the Nkx2-5 gene are a main cause of congenital heart disease. Several studies have addressed the phenotypic consequences of disrupting the Nkx2-5 gene locus, although animal models to date failed to recapitulate the full spectrum of the human disease. Here, we describe a new Nkx2-5 point mutation murine model, akin to its human counterpart disease–generating mutation. Our model fully reproduces the morphological and physiological clinical presentations of the disease and reveals an understudied aspect of Nkx2-5–driven pathology, a primary right ventricular dysfunction. We further describe the molecular consequences of disrupting the transcriptional network regulated by Nkx2-5 in the heart and show that Nkx2-5–dependent perturbation of the Wnt signaling pathway promotes heart dysfunction through alteration of cardiomyocyte metabolism. Our data provide mechanistic insights on how Nkx2-5 regulates heart function and metabolism, a link in the study of congenital heart disease, and confirms that our models are the first murine genetic models to our knowledge to present all spectra of clinically relevant adult congenital heart disease phenotypes generated by NKX2-5 mutations in patients.

Authors

Milena B. Furtado, Julia C. Wilmanns, Anjana Chandran, Joelle Perera, Olivia Hon, Christine Biben, Taylor J. Willow, Hieu T. Nim, Gurpreet Kaur, Stephanie Simonds, Qizhu Wu, David Willians, Ekaterina Salimova, Nicolas Plachta, James M. Denegre, Stephen A. Murray, Diane Fatkin, Michael Cowley, James T. Pearson, David Kaye, Mirana Ramialison, Richard P. Harvey, Nadia A. Rosenthal, Mauro W. Costa

NET silencing by let-7i in postural tachycardia syndrome

• Text
• PDF

Abstract

While strongly implicated in postural tachycardia syndrome (POTS), considerable controversy exists regarding norepinephrine transporter (NET) loss of function. POTS is characterized by the clinical symptoms of orthostatic intolerance, lightheadedness, tachycardia, and syncope or near syncope with upright posture. Abnormal sympathetic nervous system activity is typical, of a type which suggests dysfunction of the NET, with evidence that the gene responsible is under tight epigenetic control. Using RNA of isolated chromatin combined with massive parallel sequencing (RICh-seq) we show that let-7i miRNA suppresses NET by methyl-CpG-binding protein 2 (MeCP2). Vorinostat restores epigenetic control and NET expression in leukocytes derived from POTS participants.

Authors

Abdul Waheed Khan, Mark Ziemann, Susan J. Corcoran, Harikrishnan K.N, Jun Okabe, Haloom Rafehi, Scott S. Maxwell, Murray D. Esler, Assam El-Osta

Elucidation of MRAS-mediated Noonan syndrome with cardiac hypertrophy

• Text
• PDF

Abstract

Noonan syndrome (NS; MIM 163950) is an autosomal dominant disorder and a member of a family of developmental disorders termed “RASopathies,” which are caused mainly by gain-of-function mutations in genes encoding RAS/MAPK signaling pathway proteins. Whole exome sequencing (WES) and trio-based genomic triangulation of a 15-year-old female with a clinical diagnosis of NS and concomitant cardiac hypertrophy and her unaffected parents identified a de novo variant in MRAS-encoded RAS-related protein 3 as the cause of her disease. Mutation analysis using in silico mutation prediction tools and molecular dynamics simulations predicted the identified variant, p.Gly23Val-MRAS, to be damaging to normal protein function and adversely affect effector interaction regions and the GTP-binding site. Subsequent ectopic expression experiments revealed a 40-fold increase in MRAS activation for p.Gly23Val-MRAS compared with WT-MRAS. Additional biochemical assays demonstrated enhanced activation of both RAS/MAPK pathway signaling and downstream gene expression in cells expressing p.Gly23Val-MRAS. Mutational analysis of MRAS in a cohort of 109 unrelated patients with phenotype-positive/genotype-negative NS and cardiac hypertrophy yielded another patient with a sporadic de novo MRAS variant (p.Thr68Ile, c.203C>T). Herein, we describe the discovery of mutations in MRAS in patients with NS and cardiac hypertrophy, establishing MRAS as the newest NS with cardiac hypertrophy-susceptibility gene.

Authors

Erin M. Higgins, J. Martijn Bos, Heather Mason-Suares, David J. Tester, Jaeger P. Ackerman, Calum A. MacRae, Katia Sol-Church, Karen W. Gripp, Raul Urrutia, Michael J. Ackerman

Discerning functional hierarchies of microRNAs in pulmonary hypertension

• Text
• PDF

Abstract

Pulmonary hypertension (PH) is a multifaceted vascular disease where development and severity are determined by both genetic and environmental factors. Over the past decade, there has been an acceleration of the discovery of molecular effectors that mediate PH pathogenesis, including large numbers of microRNA molecules that are expressed in pulmonary vascular cell types and exert system-wide regulatory functions in all aspects of vascular health and disease. Due to the inherent pleiotropy, overlap, and redundancy of these molecules, it has been challenging to define their integrated effects on overall disease manifestation. In this review, we summarize our current understanding of the roles of microRNAs in PH with an emphasis on potential methods to discern the hierarchical motifs governing their multifunctional and interconnected activities. Deciphering this higher order of regulatory structure will be crucial for overcoming the challenges of developing these molecules as biomarkers or therapeutic targets, in isolation or combination.

Authors

Vinny Negi, Stephen Y. Chan

Mitophagy and mitochondrial biogenesis in atrial tissue of patients undergoing heart surgery with cardiopulmonary bypass

• Text
• PDF

Abstract

Mitophagy occurs during ischemia/reperfusion (I/R) and limits oxidative stress and injury. Mitochondrial turnover was assessed in patients undergoing cardiac surgery involving cardiopulmonary bypass (CPB). Paired biopsies of right atrial appendage before initiation and after weaning from CPB were processed for protein analysis, mitochondrial DNA/nuclear DNA ratio (mtDNA:nucDNA ratio), mtDNA damage, mRNA, and polysome profiling. Mitophagy in the post-CPB samples was evidenced by decreased levels of mitophagy adapters NDP52 and optineurin in whole tissue lysate, decreased Opa1 long form, and translocation of Parkin to the mitochondrial fraction. PCR analysis of mtDNA comparing amplification of short vs. long segments of mtDNA revealed increased damage following cardiac surgery. Surprisingly, a marked increase in several mitochondria-specific protein markers and mtDNA:nucDNA ratio was observed, consistent with increased mitochondrial biogenesis. mRNA analysis suggested that mitochondrial biogenesis was traniscription independent and likely driven by increased translation of existing mRNAs. These findings demonstrate in humans that both mitophagy and mitochondrial biogenesis occur during cardiac surgery involving CPB. We suggest that mitophagy is balanced by mitochondrial biogenesis during I/R stress experienced during surgery. Mitigating mtDNA damage and elucidating mechanisms regulating mitochondrial turnover will lead to interventions to improve outcome after I/R in the setting of heart disease.

Authors

Allen M. Andres, Kyle C. Tucker, Amandine Thomas, David J.R. Taylor, David Sengstock, Salik M. Jahania, Reza Dabir, Somayeh Pourpirali, Jamelle A. Brown, David G. Westbrook, Scott W. Ballinger, Robert M. Mentzer Jr., Roberta A. Gottlieb

Alterations in sarcomere function modify the hyperplastic to hypertrophic transition phase of mammalian cardiomyocyte development

• Text
• PDF

Abstract

It remains unclear how perturbations in cardiomyocyte sarcomere function alter postnatal heart development. We utilized murine models that allowed manipulation of cardiac myosin-binding protein C (MYBPC3) expression at critical stages of cardiac ontogeny to study the response of the postnatal heart to disrupted sarcomere function. We discovered that the hyperplastic to hypertrophic transition phase of mammalian heart development was altered in mice lacking MYBPC3 and this was the critical period for subsequent development of cardiomyopathy. Specifically, MYBPC3-null hearts developed evidence of increased cardiomyocyte endoreplication, which was accompanied by enhanced expression of cell cycle stimulatory cyclins and increased phosphorylation of retinoblastoma protein. Interestingly, this response was self-limited at later developmental time points by an upregulation of the cyclin-dependent kinase inhibitor p21. These results provide valuable insights into how alterations in sarcomere protein function modify postnatal heart development and highlight the potential for targeting cell cycle regulatory pathways to counteract cardiomyopathic stimuli.

Authors

Benjamin R. Nixon, Alexandra F. Williams, Michael S. Glennon, Alejandro E. de Feria, Sara C. Sebag, H. Scott Baldwin, Jason R. Becker

Myocardial microRNAs associated with reverse remodeling in human heart failure

• Text
• PDF

Abstract

BACKGROUND. In dilated cardiomyopathies (DCMs) changes in expression of protein-coding genes are associated with reverse remodeling, and these changes can be regulated by microRNAs (miRs). We tested the general hypothesis that dynamic changes in myocardial miR expression are predictive of β-blocker–associated reverse remodeling.

METHODS. Forty-three idiopathic DCM patients (mean left ventricular ejection fraction 0.24 ± 0.09) were treated with β-blockers. Serial ventriculography and endomyocardial biopsies were performed at baseline, and after 3 and 12 months of treatment. Changes in RT-PCR (candidate miRs) or array-measured miRs were compared based on the presence (R) or absence (NR) of a reverse-remodeling response, and a miR-mRNA-function pathway analysis (PA) was performed.

RESULTS. At 3 months, 2 candidate miRs were selectively changed in Rs, decreases in miR-208a-3p and miR-591. PA revealed changes in miR-mRNA interactions predictive of decreased apoptosis and myocardial cell death. At 12 months, 5 miRs exhibited selective changes in Rs (decreases in miR-208a-3p, -208b-3p, 21-5p, and 199a-5p; increase in miR-1-3p). PA predicted decreases in apoptosis, cardiac myocyte cell death, hypertrophy, and heart failure, with increases in contractile and overall cardiac functions.

CONCLUSIONS. In DCMs, myocardial miRs predict the time-dependent reverse-remodeling response to β-blocker treatment, and likely regulate the expression of remodeling-associated miRs.

TRIAL REGISTRATION. ClinicalTrials.gov NCT01798992.

FUNDING. NIH 2R01 HL48013, 1R01 HL71118 (Bristow, PI); sponsored research agreements from Glaxo-SmithKline and AstraZeneca (Bristow, PI); NIH P20 HL101435 (Lowes, Port multi-PD/PI); sponsored research agreement from Miragen Therapeutics (Port, PI).

Authors

Carmen C. Sucharov, David P. Kao, J. David Port, Anis Karimpour-Fard, Robert A. Quaife, Wayne Minobe, Karin Nunley, Brian D. Lowes, Edward M. Gilbert, Michael R. Bristow

Ganglionic GFAP⁺ glial Gq-GPCR signaling enhances heart functions in vivo

• Text
• PDF

Abstract

The sympathetic nervous system (SNS) accelerates heart rate, increases cardiac contractility, and constricts resistance vessels. The activity of SNS efferent nerves is generated by a complex neural network containing neurons and glia. Gq G protein–coupled receptor (Gq-GPCR) signaling in glial fibrillary acidic protein–expressing (GFAP⁺) glia in the central nervous system supports neuronal function and regulates neuronal activity. It is unclear how Gq-GPCR signaling in GFAP⁺ glia affects the activity of sympathetic neurons or contributes to SNS-regulated cardiovascular functions. In this study, we investigated whether Gq-GPCR activation in GFAP⁺ glia modulates the regulatory effect of the SNS on the heart; transgenic mice expressing Gq-coupled DREADD (designer receptors exclusively activated by designer drugs) (hM3Dq) selectively in GFAP⁺ glia were used to address this question in vivo. We found that acute Gq-GPCR activation in peripheral GFAP⁺ glia significantly accelerated heart rate and increased left ventricle contraction. Pharmacological experiments suggest that the glial-induced cardiac changes were due to Gq-GPCR activation in satellite glial cells within the sympathetic ganglion; this activation led to increased norepinephrine (NE) release and beta-1 adrenergic receptor activation within the heart. Chronic glial Gq-GPCR activation led to hypotension in female Gfap-hM3Dq mice. This study provides direct evidence that Gq-GPCR activation in peripheral GFAP⁺ glia regulates cardiovascular functions in vivo.

Authors

Alison Xiaoqiao Xie, Jakovin J. Lee, Ken D. McCarthy

Vps34 regulates myofibril proteostasis to prevent hypertrophic cardiomyopathy

• Text
• PDF

Abstract

Hypertrophic cardiomyopathy (HCM) is a common heart disease with a prevalence of 1 in 500 in the general population. Several mutations in genes encoding cardiac proteins have been found in HCM patients, but these changes do not predict occurrence or prognosis and the molecular mechanisms underlying HCM remain largely elusive. Here we show that cardiac expression of vacuolar protein sorting 34 (Vps34) is reduced in a subset of HCM patients. In a mouse model, muscle-specific loss of Vps34 led to HCM-like manifestations and sudden death. Vps34-deficient hearts exhibited abnormal histopathologies, including myofibrillar disarray and aggregates containing αB-crystallin (CryAB). These features result from a block in the ESCRT-mediated proteolysis that normally degrades K63-polyubiquitinated CryAB. CryAB deposition was also found in myocardial specimens from a subset of HCM patients whose hearts showed decreased Vps34. Our results identify disruption of the previously unknown Vps34-CryAB axis as a potentially novel etiology of HCM.

Authors

Hirotaka Kimura, Satoshi Eguchi, Junko Sasaki, Keiji Kuba, Hiroki Nakanishi, Shunsuke Takasuga, Masakazu Yamazaki, Akiteru Goto, Hiroyuki Watanabe, Hiroshi Itoh, Yumiko Imai, Akira Suzuki, Noboru Mizushima, Takehiko Sasaki

Ectonucleotidase CD39-driven control of postinfarction myocardial repair and rupture

• Text
• PDF

Abstract

Mechanical complications of myocardial infarction (MI) are often fatal. Little is known about endogenous factors that predispose to myocardial rupture after MI. Ectonucleoside triphosphate diphosphohydrolase (CD39) could be a critical mediator of propensity to myocardial rupture after MI due to its role in modulating inflammation and thrombosis. Using a model of permanent coronary artery ligation, rupture was virtually abrogated in cd39^–/– mice versus cd39^+/+ controls, with elevated fibrin and collagen deposition and marked neutrophil and macrophage influx. Macrophages were found to display increased surface expression of CD301 and CD206, marking a reparative phenotype, driven by increased extracellular ATP and IL-4 in the infarcted myocardium of cd39^–/– mice. A myeloid-specific CD39-knockout mouse also demonstrated protection from rupture, with an attenuated rupture phenotype, suggesting that complete ablation of CD39 provides the greatest degree of protection in this model. Absence of CD39, either globally or in a myeloid lineage–restricted fashion, skews the phenotype toward alternatively activated (reparative) macrophage infiltration following MI. These studies reveal a previously unrecognized and unexpected role of endogenous CD39 to skew macrophage phenotype and promote a propensity to myocardial rupture after MI.

Authors

Nadia R. Sutton, Takanori Hayasaki, Matthew C. Hyman, Anuli C. Anyanwu, Hui Liao, Danica Petrovic-Djergovic, Linda Badri, Amy E. Baek, Natalie Walker, Keigo Fukase, Yogendra Kanthi, Scott H. Visovatti, Ellen L. Horste, Jessica J. Ray, Sascha N. Goonewardena, David J. Pinsky

Identifying the third dimension in 2D fluoroscopy to create 3D cardiac maps

• Text
• PDF

Abstract

Three-dimensional cardiac mapping is important for optimal visualization of the heart during cardiac ablation for the treatment of certain arrhythmias. However, many hospitals and clinics worldwide cannot afford the high cost of the current mapping systems. We set out to determine if, using predefined algorithms, comparable 3D cardiac maps could be created by a new device that relies on data generated from single-plane fluoroscopy and patient recording and monitoring systems, without the need for costly equipment, infrastructure changes, or specialized catheters. The study included phantom and animal experiments to compare the prototype test device, Navik 3D, with the existing CARTO 3 System. The primary endpoint directly compared: (a) the 3D distance between the Navik 3D–simulated ablation location and the back-projected ground truth location of the pacing and mapping catheter electrode, and (b) the same distance for CARTO. The study’s primary objective was considered met if the 95% confidence lower limit was greater than 0.75% for the Navik 3D–CARTO difference between the 2 distances, or less than or equal to 2 mm. Study results showed that the Navik 3D performance was equivalent to the CARTO system, and that accurate 3D cardiac maps can be created using data from equipment that already exists in all electrophysiology labs.

Authors

Jasbir Sra, David Krum, Indrajit Choudhuri, Barry Belanger, Mark Palma, Donald Brodnick, Daniel B. Rowe

Interleukin 6 regulates psoriasiform inflammation–associated thrombosis

• Text
• PDF

Abstract

Psoriasis patients are at increased risk of heart attack and stroke and have elevated MRP8/14 levels that predict heart attack. The KC-Tie2 psoriasiform mouse model exhibits elevated MRP8/14 and is prothrombotic. Mrp14^–/– mice, in contrast, are protected from thrombosis, but, surprisingly, KC-Tie2xMrp14^–/– mice remain prothrombotic. Treating KC-Tie2xMrp14^–/– mice with anti–IL-23p19 antibodies reversed the skin inflammation, improved thrombosis, and decreased IL-6. In comparison, IL-6 deletion from KC-Tie2 animals improved thrombosis despite sustained skin inflammation, suggesting that thrombosis improvements following IL-23 inhibition occur secondary to IL-6 decreases. Psoriasis patient skin has elevated IL-6 and IL-6 receptor is present in human coronary atheroma, supporting a link between skin and distant vessel disease in patient tissue. Together, these results identify a critical role for skin-derived IL-6 linking skin inflammation with thrombosis, and shows that in the absence of IL-6 the connection between skin inflammation and thrombosis comorbidities is severed.

Authors

Yunmei Wang, Jackelyn B. Golden, Yi Fritz, Xiufen Zhang, Doina Diaconu, Maya I. Camhi, Huiyun Gao, Sean M. Dawes, Xianying Xing, Santhi K. Ganesh, Johann E. Gudjonsson, Daniel I. Simon, Thomas S. McCormick, Nicole L. Ward