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Behrmann A, Cayton J, Hayden MR, Lambert MD, Nourian Z, Nyanyo K, Godbee B, Hanft LM, Krenz M, McDonald KS, Domeier TL. Right ventricular preload and afterload challenge induces contractile dysfunction and arrhythmia in isolated hearts of dystrophin-deficient male mice. Physiol Rep 2024; 12:e16004. [PMID: 38658324 PMCID: PMC11043033 DOI: 10.14814/phy2.16004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/13/2024] [Accepted: 03/27/2024] [Indexed: 04/26/2024] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked recessive myopathy due to mutations in the dystrophin gene. Diaphragmatic weakness in DMD causes hypoventilation and elevated afterload on the right ventricle (RV). Thus, RV dysfunction in DMD develops early in disease progression. Herein, we deliver a 30-min sustained RV preload/afterload challenge to isolated hearts of wild-type (Wt) and dystrophic (Dmdmdx-4Cv) mice at both young (2-6 month) and middle-age (8-12 month) to test the hypothesis that the dystrophic RV is susceptible to dysfunction with elevated load. Young dystrophic hearts exhibited greater pressure development than wild type under baseline (Langendorff) conditions, but following RV challenge exhibited similar contractile function as wild type. Following the RV challenge, young dystrophic hearts had an increased incidence of premature ventricular contractions (PVCs) compared to wild type. Hearts of middle-aged wild-type and dystrophic mice had similar contractile function during baseline conditions. After RV challenge, hearts of middle-aged dystrophic mice had severe RV dysfunction and arrhythmias, including ventricular tachycardia. Following the RV load challenge, dystrophic hearts had greater lactate dehydrogenase (LDH) release than wild-type mice indicative of damage. Our data indicate age-dependent changes in RV function with load in dystrophin deficiency, highlighting the need to avoid sustained RV load to forestall dysfunction and arrhythmia.
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MESH Headings
- Animals
- Male
- Dystrophin/genetics
- Dystrophin/deficiency
- Mice
- Myocardial Contraction
- Arrhythmias, Cardiac/physiopathology
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/genetics
- Ventricular Dysfunction, Right/physiopathology
- Ventricular Dysfunction, Right/genetics
- Ventricular Dysfunction, Right/metabolism
- Muscular Dystrophy, Duchenne/physiopathology
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/complications
- Muscular Dystrophy, Duchenne/metabolism
- Mice, Inbred mdx
- Mice, Inbred C57BL
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Affiliation(s)
- Andrew Behrmann
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Jessica Cayton
- Department of Veterinary PathobiologyUniversity of MissouriColumbiaMissouriUSA
| | - Matthew R. Hayden
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Michelle D. Lambert
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Zahra Nourian
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Keith Nyanyo
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Brooke Godbee
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Laurin M. Hanft
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Maike Krenz
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
- Dalton Cardiovascular Research CenterUniversity of MissouriColumbiaMissouriUSA
| | - Kerry S. McDonald
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Timothy L. Domeier
- Medical Pharmacology and PhysiologyUniversity of MissouriColumbiaMissouriUSA
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Zhou Z, Xu R, Cai X, Fu H, Xu K, Yuan W, Song Y, Shi K, Fu C, Li X, Wang C, Guo Y, Yu L, Xu H. Association Between Myocardial Oxygenation and Fibrosis in Duchenne Muscular Dystrophy: Analysis by Rest Oxygenation-Sensitive Magnetic Resonance Imaging. J Magn Reson Imaging 2024. [PMID: 38328865 DOI: 10.1002/jmri.29273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/20/2024] [Accepted: 01/22/2024] [Indexed: 02/09/2024] Open
Abstract
BACKGROUND Myocardial hypoxia has been demonstrated in many cardiomyopathies and is related to development of myocardial fibrosis. However, myocardial hypoxia and its association with myocardial fibrosis are understudied in Duchenne muscular dystrophy (DMD)-associated cardiomyopathy. PURPOSE To evaluate myocardial hypoxia by oxygenation-sensitive (OS) cardiac magnetic resonance imaging, and further explore its association with fibrosis. STUDY TYPE Prospective. SUBJECTS Ninety-one DMD boys (8.78 ± 2.32) and 30 healthy boys (9.07 ± 2.30). FIELD STRENGTH/SEQUENCE 3 T, Balanced steady-state free procession, Modified Look-Locker inversion recovery sequence and Single-shot phase-sensitive inversion recovery sequence. ASSESSMENT Cardiac MRI data, including left ventricular functional, segmental native T1, and oxygenation signal-intensity (SI) according to AHA 17-segment model, were acquired. Patients were divided into LGE+ and LGE- groups. In patients with LGE, all segments were further classified as positive or negative segments by segmentally presence/absence of LGE. STATISTICAL TESTS Variables were compared using Student's t, Wilcoxon, Kruskal-Wallis test and one-way analysis of variance. Bivariate Pearson or Spearman correlation were calculated to determine association between oxygenation SI and native T1. Variables with P < 0.10 in the univariable analysis were included in multivariable model. Receiver operating characteristic analysis was used to assess the performance of OS in diagnosing myocardial hypoxia. RESULTS The myocardial oxygenation SI of DMD was significantly decreased in all segments compared with normal controls, and more obvious in the LGE+ segments (0.46 ± 0.03 vs. 0.52 ± 0.03). For patients with and without LGE, myocardial oxygenation SI were significantly negatively correlated with native T1 in all segments (r = -0.23 to -0.42). The inferolateral oxygenation SI was a significant independent associator of LGE presence (adjusted OR = 0.900). DATA CONCLUSION Myocardial hypoxia evaluated by the OS-Cardiac-MRI indeed occurs in DMD and associate with myocardial fibrosis, which might be used as a biomarker in assessing myocardial damage in DMD. EVIDENCE LEVEL 1 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Ziqi Zhou
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Rong Xu
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Xiaotang Cai
- Department of Rehabilitation, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Hang Fu
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Ke Xu
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Weifeng Yuan
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yu Song
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Ke Shi
- Department of Radiology, West China Hospital, Sichuan University, Chengdu, China
| | - Chuan Fu
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Xuesheng Li
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Chuan Wang
- Department of Cardiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yingkun Guo
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Li Yu
- Department of Cardiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Huayan Xu
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
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3
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Stevens JA, Dobratz TC, Fischer KD, Palmer A, Bourdage K, Wong AJ, Chapoy-Villanueva H, Garry DJ, Liu JC, Kay MW, Kuzmiak-Glancy S, Townsend D. Mechanisms of reduced myocardial energetics of the dystrophic heart. Am J Physiol Heart Circ Physiol 2024; 326:H396-H407. [PMID: 38099842 PMCID: PMC11219055 DOI: 10.1152/ajpheart.00636.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/07/2023] [Accepted: 12/12/2023] [Indexed: 01/23/2024]
Abstract
Heart disease is a leading cause of death in patients with Duchenne muscular dystrophy (DMD), characterized by the progressive replacement of contractile tissue with scar tissue. Effective therapies for dystrophic cardiomyopathy will require addressing the disease before the onset of fibrosis, however, the mechanisms of the early disease are poorly understood. To understand the pathophysiology of DMD, we perform a detailed functional assessment of cardiac function of the mdx mouse, a model of DMD. These studies use a combination of functional, metabolomic, and spectroscopic approaches to fully characterize the contractile, energetic, and mitochondrial function of beating hearts. Through these innovative approaches, we demonstrate that the dystrophic heart has reduced cardiac reserve and is energetically limited. We show that this limitation does not result from poor delivery of oxygen. Using spectroscopic approaches, we provide evidence that mitochondria in the dystrophic heart have attenuated mitochondrial membrane potential and deficits in the flow of electrons in complex IV of the electron transport chain. These studies provide evidence that poor myocardial energetics precede the onset of significant cardiac fibrosis and likely results from mitochondrial dysfunction centered around complex IV and reduced membrane potential. The multimodal approach used here implicates specific molecular components in the etiology of reduced energetics. Future studies focused on these targets may provide therapies that improve the energetics of the dystrophic heart leading to improved resiliency against damage and preservation of myocardial contractile tissue.NEW & NOTEWORTHY Dystrophic hearts have poor contractile reserve that is associated with a reduction in myocardial energetics. We demonstrate that oxygen delivery does not contribute to the limited energy production of the dystrophic heart even with increased workloads. Cytochrome optical spectroscopy of the contracting heart reveals alterations in complex IV and evidence of depolarized mitochondrial membranes. We show specific alterations in the electron transport chain of the dystrophic heart that may contribute to poor myocardial energetics.
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Affiliation(s)
- Jackie A Stevens
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Tyler C Dobratz
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Kaleb D Fischer
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Alexandria Palmer
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Kira Bourdage
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Anne J Wong
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Hector Chapoy-Villanueva
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
- Institute for Obesity Research Tecnologico de Monterrey, Monterrey, Mexico
| | - Daniel J Garry
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
- Lillehei Heart Institute, Cardiovascular Division, University of Minnesota, Minneapolis, Minnesota, United States
- Paul and Sheila Muscular Dystrophy Center, University of Minnesota, Minneapolis, Minnesota, United States
| | - Julia C Liu
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Matthew W Kay
- Department of Biomedical Engineering, School of Engineering and Applied Science, George Washington University, Washington, District of Columbia, United States
| | - Sarah Kuzmiak-Glancy
- Department of Kinesiology, School of Public Health, University of Maryland, College Park, Maryland, United States
| | - DeWayne Townsend
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
- Lillehei Heart Institute, Cardiovascular Division, University of Minnesota, Minneapolis, Minnesota, United States
- Paul and Sheila Muscular Dystrophy Center, University of Minnesota, Minneapolis, Minnesota, United States
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4
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Zhang N, Harsch B, Zhang MJ, Gyberg DJ, Stevens JA, Wagner BM, Mendelson J, Patterson MT, Orchard DA, Healy CL, Williams JW, Townsend D, Shearer GC, Murphy KA, O'Connell TD. FFAR4 regulates cardiac oxylipin balance to promote inflammation resolution in HFpEF secondary to metabolic syndrome. J Lipid Res 2023; 64:100374. [PMID: 37075982 PMCID: PMC10209340 DOI: 10.1016/j.jlr.2023.100374] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 04/21/2023] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) is a complex clinical syndrome, but a predominant subset of HFpEF patients has metabolic syndrome (MetS). Mechanistically, systemic, nonresolving inflammation associated with MetS might drive HFpEF remodeling. Free fatty acid receptor 4 (Ffar4) is a GPCR for long-chain fatty acids that attenuates metabolic dysfunction and resolves inflammation. Therefore, we hypothesized that Ffar4 would attenuate remodeling in HFpEF secondary to MetS (HFpEF-MetS). To test this hypothesis, mice with systemic deletion of Ffar4 (Ffar4KO) were fed a high-fat/high-sucrose diet with L-NAME in their water to induce HFpEF-MetS. In male Ffar4KO mice, this HFpEF-MetS diet induced similar metabolic deficits but worsened diastolic function and microvascular rarefaction relative to WT mice. Conversely, in female Ffar4KO mice, the diet produced greater obesity but no worsened ventricular remodeling relative to WT mice. In Ffar4KO males, MetS altered the balance of inflammatory oxylipins systemically in HDL and in the heart, decreasing the eicosapentaenoic acid-derived, proresolving oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE), while increasing the arachidonic acid-derived, proinflammatory oxylipin 12-hydroxyeicosatetraenoic acid (12-HETE). This increased 12-HETE/18-HEPE ratio reflected a more proinflammatory state both systemically and in the heart in male Ffar4KO mice and was associated with increased macrophage numbers in the heart, which in turn correlated with worsened ventricular remodeling. In summary, our data suggest that Ffar4 controls the proinflammatory/proresolving oxylipin balance systemically and in the heart to resolve inflammation and attenuate HFpEF remodeling.
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Affiliation(s)
- Naixin Zhang
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Brian Harsch
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Michael J Zhang
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Dylan J Gyberg
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Jackie A Stevens
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Brandon M Wagner
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Jenna Mendelson
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | | | - Devin A Orchard
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Chastity L Healy
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Jesse W Williams
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA; Center for Immunology, University of Minnesota, Minneapolis, MN, USA
| | - DeWayne Townsend
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Gregory C Shearer
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA.
| | - Katherine A Murphy
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA.
| | - Timothy D O'Connell
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA.
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5
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Uryash A, Mijares A, Estève E, Adams JA, Lopez JR. Smooth Muscle Cells of Dystrophic (mdx) Mice Are More Susceptible to Hypoxia; The Protective Effect of Reducing Ca 2+ Influx. Biomedicines 2023; 11:biomedicines11020623. [PMID: 36831159 PMCID: PMC9953629 DOI: 10.3390/biomedicines11020623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/13/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is an inherited muscular disorder caused by mutations in the dystrophin gene. DMD patients have hypoxemic events due to sleep-disordered breathing. We reported an anomalous regulation of resting intracellular Ca2+ ([Ca2+]i) in vascular smooth muscle cells (VSMCs) from a mouse (mdx) model of DMD. We investigated the effect of hypoxia on [Ca2+]i in isolated and quiescent VSMCs from C57BL/10SnJ (WT) and C57BL/10ScSn-Dmd (mdx) male mice. [Ca2+]i was measured using Ca2+-selective microelectrodes under normoxic conditions (95% air, 5% CO2) and after hypoxia (glucose-free solution aerated with 95% N2-5% CO2 for 30 min). [Ca2+]i in mdx VSMCs was significantly elevated compared to WT under normoxia. Hypoxia-induced [Ca2+]i overload, which was significantly greater in mdx than in WT VSMCs. A low Ca2+ solution caused a reduction in [Ca2+]i and prevented [Ca2+]i overload secondary to hypoxia. Nifedipine (10 µM), a Ca2+ channel blocker, did not modify resting [Ca2+]i in VSMCs but partially prevented the hypoxia-induced elevation of [Ca2+]i in both genotypes. SAR7334 (1 µM), an antagonist of TRPC3 and TRPC6, reduced the basal and [Ca2+]i overload caused by hypoxia. Cell viability, assessed by tetrazolium salt (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, was significantly reduced in mdx compared to WT VSMCs. Pretreatment with SAR7341 increases cell viability in normoxic mdx (p < 0.001) and during hypoxia in WT and mdx VSMCs. These results provide evidence that the lack of dystrophin makes VSMCs more susceptible to hypoxia-induced [Ca2+]i overload, which appears to be mediated by increased Ca2+ entry through L-type Ca2+ and TRPC channels.
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Affiliation(s)
- Arkady Uryash
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL 33140, USA
| | - Alfredo Mijares
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas 21827, Venezuela
| | - Eric Estève
- PhyMedExp, University of Montpellier, CNRS, INSERM, CHRU Montpellier, 34090 Montpellier, France
- Univ. Grenoble Alpes, CNRS, TIMC-IMAG/PRETA (UMR 5525), 38000 Grenoble, France
| | - Jose A. Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL 33140, USA
| | - Jose R. Lopez
- Department of Research, Mount Sinai Medical Center, Miami Beach, FL 33140, USA
- Correspondence: ; Tel.: +1-305-674-2727
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Li R, Wang H, Ma F, Cui GL, Peng LY, Li CZ, Zeng HS, Marian AJ, Wang DW. Widespread myocardial dysfunction in COVID-19 patients detected by myocardial strain imaging using 2-D speckle-tracking echocardiography. Acta Pharmacol Sin 2021; 42:1567-1574. [PMID: 33510459 PMCID: PMC7842392 DOI: 10.1038/s41401-020-00595-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/07/2020] [Indexed: 01/08/2023] Open
Abstract
COVID-19 is a multiorgan systemic inflammatory disease caused by SARS-CoV-2 virus. Patients with COVID-19 often exhibit cardiac dysfunction and myocardial injury, but imaging evidence is lacking. In the study we detected and evaluated the severity of myocardial dysfunction in COVID-19 patient population using two-dimensional speckle-tracking echocardiography (2-D STE). A total of 218 consecutive patients with confirmed diagnosis of COVID-19 who had no underlying cardiovascular diseases were enrolled and underwent transthoracic echocardiography. This study cohort included 52 (23.8%) critically ill and 166 noncritically ill patients. Global longitudinal strains (GLSs) and layer-specific longitudinal strains (LSLSs) were obtained using 2-D STE. Changes in GLS were correlated with the clinical parameters. We showed that GLS was reduced (<-21.0%) in about 83% of the patients. GLS reduction was more common in critically sick patients (98% vs. 78.3%, P < 0.001), and the mean GLS was significantly lower in the critically sick patients than those noncritical (-13.7% ± 3.4% vs. -17.4% ± 3.2%, P < 0.001). The alteration of GLS was more prominent in the subepicardium than in the subendocardium (P < 0.001). GLS was correlated to mean serum pulse oxygen saturation (SpO2, RR = 0.42, P < 0.0001), high-sensitive C-reactive protein (hsCRP, R = -0.20, P = 0.006) and inflammatory cytokines, particularly IL-6 (R = -0.21, P = 0.003). In conclusions, our results demonstrate that myocardial dysfunction is common in COVID-19 patients, particularly those who are critically sick. Changes in indices of myocardial strain were associated with indices of inflammatory markers and hypoxia, suggesting partly secondary nature of myocardial dysfunction.
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Li H, Niu N, Yang J, Dong F, Zhang T, Li S, Zhao W. Nuclear respiratory factor 1 protects H9C2 cells against hypoxia-induced apoptosis via the death receptor pathway and mitochondrial pathway. Cell Biol Int 2021; 45:1784-1796. [PMID: 33913583 DOI: 10.1002/cbin.11619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/06/2021] [Accepted: 04/18/2021] [Indexed: 12/22/2022]
Abstract
Hypoxia-induced cardiomyocyte apoptosis is one of the leading causes of heart failure. Nuclear respiratory factor 1 (NRF-1) was suggested as a protector against cell apoptosis; However, the mechanism is not clear. Therefore, the aim of this study was to elucidate the role of NRF-1 in hypoxia-induced H9C2 cardiomyocyte apoptosis and to explore its effect on regulating the death receptor pathway and mitochondrial pathway. NRF-1 was overexpressed or knocked down in H9C2 cells, which were then exposed to a hypoxia condition for 0, 3, 6, 12, and 24 h. Changes in cell proliferation, cell viability, reactive oxygen species (ROS) generation, and mitochondrial membrane potential (MMP) were investigated. The activities of caspase-3, -8, and -9, apoptosis rate, and the gene and protein expression levels of the death receptor pathway and mitochondrial pathway were analyzed. Under hypoxia exposure, NRF-1 overexpression improved the proliferation and viability of H9C2 cells and decreased ROS generation, MMP loss, caspase activities, and the apoptosis rate. However, the NRF-1 knockdown group showed the opposite results. Additionally, NRF-1 upregulated the expression of antiapoptotic molecules involved in the death receptor and mitochondrial pathways, such as CASP8 and FADD-like apoptosis regulator, B-cell lymphoma 2, B-cell lymphoma-extra-large, and cytochrome C. Conversely, the expression of proapoptotic molecules, such as caspase-8, BH3-interacting domain death agonist, Bcl-2-associated X protein, caspase-9, and caspase-3 was downregulated by NRF-1 overexpression in hypoxia-induced H9C2 cells. These results suggest that NRF-1 functions as an antiapoptotic factor in the death receptor and mitochondrial pathways to mitigate hypoxia-induced apoptosis in H9C2 cardiomyocytes.
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Affiliation(s)
- Hui Li
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
| | - Nan Niu
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
| | - Jihui Yang
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
| | - Fei Dong
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
| | - Tingrui Zhang
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
| | - Shasha Li
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
| | - Wei Zhao
- College of Basic Medicine, Ningxia Medical University, Yinchuan, China
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8
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Abstract
Understanding the energetic state of the heart is essential for unraveling the central tenets of cardiac physiology. The heart uses a tremendous amount of energy and reductions in that energy supply can have lethal consequences. While ischemic events clearly result in significant metabolic perturbations, heart failure with both preserved and reduced ejection fraction display reductions in energetic status. To date, most cardiac energetics have been performed using 31P-NMR, which requires dedicated access to a specialized NMR spectrometer. This has limited the availability of this method to a handful of centers around the world. Here we present a method of assessing myocardial energetics in the isolated mouse heart using 1H-NMR spectrometers that are widely available in NMR core facilities. In addition, this methodology provides information on many other important metabolites within the heart, including unique metabolic differences between the hypoxic and ischemic hearts. Furthermore, we demonstrate the correlation between myocardial energetics and measures of contractile function in the mouse heart. These methods will allow a broader examination of myocardial energetics providing a valuable tool to aid in the understanding of the nature of these energetic deficits and to develop therapies directed at improving myocardial energetics in failing hearts.
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Ischemia/hypoxia inhibits cardiomyocyte autophagy and promotes apoptosis via the Egr-1/Bim/Beclin-1 pathway. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2020; 17:284-293. [PMID: 32547612 PMCID: PMC7276312 DOI: 10.11909/j.issn.1671-5411.2020.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Background Myocardial injury caused by microvascular obstruction (MVO) is characterized by persistent ischemia/hypoxia (IH) of cardiomyocytes after microembolization. Autophagy and Egr-1 were closely associated with various cardiovascular diseases, including MVO. Bim and Beclin-1 are the important genes for autophagy and apoptosis. We aimed to explore whether the Egr-1/Bim/Beclin-1 pathway is involved in regulating autophagy and apoptosis in IH-exposed cardiomyocytes. Methods Neonatal rat cardiomyocytes exposed to the IH environment in vitro were transfected with lentivirus expressing Egr-1 or Egr-1 shRNA, or further treated with 3-methyladenine (3-MA). The expressions of autophagy and apoptosis-associated genes were evaluated using RT-qPCR and Western blots assays. Autophagic vacuoles and autophagic flux were detected by transmission electron microscopy (TEM) and confocal microscope, respectively. Cell injury was assessed by lactate dehydrogenase (LDH) leakage, and apoptosis was determined by flow cytometry. Results IH exposure elevated Egr-1 and Bim expressions, and decreased Beclin-1 expression in rat cardiomyocytes. Egr-1 overexpression in IH-exposed cardiomyocytes significantly up-regulated the levels of Egr-1 and Bim, and down-regulated the level of Beclin-1. Egr-1 knockdown resulted in down-regulated expressions of Egr-1 and Bim, as well as up-regulated expression of Beclin-1. In addition, Egr-1 knockdown induced autophagy was suppressed by 3-MA treatments. TEM and autophagic flux experiments also confirmed that Egr-1 inhibited autophagy progression in IH-exposed cardiomyocytes. Egr-1 suppression protected cardiomyocytes from IH-induced injury, as evidenced by the positive correlations between Egr-1 expression and LDH leakage or apoptosis index in IH-exposed cardiomyocytes. Conclusions IH-induced cardiomyocyte autophagy and apoptosis are regulated by the Egr-1/Bim/Beclin-1 pathway, which is a potential target for treating cardiomyocyte injury caused by MVO in the IH environment.
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10
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Fischer KD, Heitzman JA, Townsend D. Hyperbaric therapy provides no benefit for skeletal muscle and respiratory function and accelerates cardiac injury in mdx mice. Sci Rep 2019; 9:12306. [PMID: 31444390 PMCID: PMC6707265 DOI: 10.1038/s41598-019-48744-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 08/07/2019] [Indexed: 12/12/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a uniformly fatal condition of striated muscle wasting resulting in premature death from respiratory and/or cardiac failure. Symptomatic therapy has prolonged survival by limiting deaths resulting from respiratory insufficiency, but there is currently no effective therapy for most patients with DMD. This grim prognosis has led patients and their families to seek unproven therapeutic approaches. One such approach is the use of hyperbaric therapies, which 14% of DMD patients self-report using. The primary goal of this study was to determine if intermittent hyperbaric exposure altered the muscle function of the mdx mouse, a genetic model of DMD. To do this, mdx mice were exposed to three daily 90-minute 1.3 atmosphere hyperbaric exposures for 4 weeks. Skeletal muscle, respiratory, and cardiac function were assessed in treated and untreated wild type and dystrophic mice. The results of these studies find that hyperbaric and hyperoxic approaches resulted in increased cardiac fibrosis in dystrophic mice and no beneficial effects on the functional parameters measured. These data suggest that these oxygen-based therapies are unlikely to provide therapeutic benefit to DMD patients.
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Affiliation(s)
- Kaleb D Fischer
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Jackie A Heitzman
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN, USA
| | - DeWayne Townsend
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN, USA.
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Meyers TA, Townsend D. Cardiac Pathophysiology and the Future of Cardiac Therapies in Duchenne Muscular Dystrophy. Int J Mol Sci 2019; 20:E4098. [PMID: 31443395 PMCID: PMC6747383 DOI: 10.3390/ijms20174098] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/12/2019] [Accepted: 08/19/2019] [Indexed: 12/25/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a devastating disease featuring skeletal muscle wasting, respiratory insufficiency, and cardiomyopathy. Historically, respiratory failure has been the leading cause of mortality in DMD, but recent improvements in symptomatic respiratory management have extended the life expectancy of DMD patients. With increased longevity, the clinical relevance of heart disease in DMD is growing, as virtually all DMD patients over 18 year of age display signs of cardiomyopathy. This review will focus on the pathophysiological basis of DMD in the heart and discuss the therapeutic approaches currently in use and those in development to treat dystrophic cardiomyopathy. The first section will describe the aspects of the DMD that result in the loss of cardiac tissue and accumulation of fibrosis. The second section will discuss cardiac small molecule therapies currently used to treat heart disease in DMD, with a focus on the evidence supporting the use of each drug in dystrophic patients. The final section will outline the strengths and limitations of approaches directed at correcting the genetic defect through dystrophin gene replacement, modification, or repair. There are several new and promising therapeutic approaches that may protect the dystrophic heart, but their limitations suggest that future management of dystrophic cardiomyopathy may benefit from combining gene-targeted therapies with small molecule therapies. Understanding the mechanistic basis of dystrophic heart disease and the effects of current and emerging therapies will be critical for their success in the treatment of patients with DMD.
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Affiliation(s)
- Tatyana A Meyers
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - DeWayne Townsend
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN 55455, USA.
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