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Jorgenson KW, Hibbert JE, Sayed RKA, Lange AN, Godwin JS, Mesquita PHC, Ruple BA, McIntosh MC, Kavazis AN, Roberts MD, Hornberger TA. A novel imaging method (FIM-ID) reveals that myofibrillogenesis plays a major role in the mechanically induced growth of skeletal muscle. eLife 2024; 12:RP92674. [PMID: 38466320 PMCID: PMC10928493 DOI: 10.7554/elife.92674] [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] [Indexed: 03/12/2024] Open
Abstract
An increase in mechanical loading, such as that which occurs during resistance exercise, induces radial growth of muscle fibers (i.e. an increase in cross-sectional area). Muscle fibers are largely composed of myofibrils, but whether radial growth is mediated by an increase in the size of the myofibrils (i.e. myofibril hypertrophy) and/or the number of myofibrils (i.e. myofibrillogenesis) is not known. Electron microscopy (EM) can provide images with the level of resolution that is needed to address this question, but the acquisition and subsequent analysis of EM images is a time- and cost-intensive process. To overcome this, we developed a novel method for visualizing myofibrils with a standard fluorescence microscope (fluorescence imaging of myofibrils with image deconvolution [FIM-ID]). Images from FIM-ID have a high degree of resolution and contrast, and these properties enabled us to develop pipelines for automated measurements of myofibril size and number. After extensively validating the automated measurements, we used both mouse and human models of increased mechanical loading to discover that the radial growth of muscle fibers is largely mediated by myofibrillogenesis. Collectively, the outcomes of this study offer insight into a fundamentally important topic in the field of muscle growth and provide future investigators with a time- and cost-effective means to study it.
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Affiliation(s)
- Kent W Jorgenson
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin-MadisonMadisonUnited States
| | - Jamie E Hibbert
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin-MadisonMadisonUnited States
| | - Ramy KA Sayed
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin-MadisonMadisonUnited States
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Sohag UniversitySohagEgypt
| | - Anthony N Lange
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin-MadisonMadisonUnited States
| | | | | | | | | | | | | | - Troy A Hornberger
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin-MadisonMadisonUnited States
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Jorgenson KW, Hibbert JE, Sayed RKA, Lange AN, Godwin JS, Mesquita PHC, Ruple BA, McIntosh MC, Kavazis AN, Roberts MD, Hornberger TA. A Novel Imaging Method (FIM-ID) Reveals that Myofibrillogenesis Plays a Major Role in the Mechanically Induced Growth of Skeletal Muscle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.13.557204. [PMID: 37745462 PMCID: PMC10515927 DOI: 10.1101/2023.09.13.557204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
An increase in mechanical loading, such as that which occurs during resistance exercise, induces radial growth of muscle fibers (i.e., an increase in cross-sectional area). Muscle fibers are largely composed of myofibrils, but whether radial growth is mediated by an increase in the size of the myofibrils (i.e., myofibril hypertrophy) and/or the number of myofibrils (i.e., myofibrillogenesis) is not known. Electron microscopy (EM) can provide images with the level of resolution that is needed to address this question, but the acquisition and subsequent analysis of EM images is a time- and cost-intensive process. To overcome this, we developed a novel method for visualizing myofibrils with a standard fluorescence microscope (FIM-ID). Images from FIM-ID have a high degree of resolution and contrast, and these properties enabled us to develop pipelines for automated measurements of myofibril size and number. After extensively validating the automated measurements, we used both mouse and human models of increased mechanical loading to discover that the radial growth of muscle fibers is largely mediated by myofibrillogenesis. Collectively, the outcomes of this study offer insight into a fundamentally important topic in the field of muscle growth and provide future investigators with a time- and cost-effective means to study it.
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Autry JM, Karim CB, Cocco M, Carlson SF, Thomas DD, Valberg SJ. Purification of sarcoplasmic reticulum vesicles from horse gluteal muscle. Anal Biochem 2020; 610:113965. [PMID: 32956693 DOI: 10.1016/j.ab.2020.113965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/24/2020] [Accepted: 09/14/2020] [Indexed: 01/09/2023]
Abstract
We have analyzed protein expression and enzyme activity of the sarcoplasmic reticulum Ca2+-transporting ATPase (SERCA) in horse gluteal muscle. Horses exhibit a high incidence of recurrent exertional rhabdomyolysis, with myosolic Ca2+ proposed, but yet to be established, as the underlying cause. To better assess Ca2+ regulatory mechanisms, we developed an improved protocol for isolating sarcoplasmic reticulum (SR) vesicles from horse skeletal muscle, based on mechanical homogenization and optimized parameters for differential centrifugation. Immunoblotting identified the peak subcellular fraction containing the SERCA1 protein (fast-twitch isoform). Gel analysis using the Stains-all dye demonstrated that calsequestrin (CASQ) and phospholipids are highly enriched in the SERCA-containing subcellular fraction isolated from horse gluteus. Immunoblotting also demonstrated that these horse SR vesicles show low content of glycogen phosphorylase (GP), which is likely an abundant contaminating protein of traditional horse SR preps. The maximal Ca2+-activated ATPase activity (Vmax) of SERCA in horse SR vesicles isolated using this protocol is 5‒25-fold greater than previously-reported SERCA activity in SR preps from horse skeletal muscle. We propose that this new protocol for isolating SR vesicles will be useful for determining enzymatic parameters of horse SERCA with high fidelity, plus assessing regulatory effect of SERCA peptide subunit(s) expressed in horse muscle.
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Affiliation(s)
- Joseph M Autry
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - Christine B Karim
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mariana Cocco
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, 55108, USA
| | - Samuel F Carlson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Stephanie J Valberg
- Department of Large Animal Clinical Sciences, McPhail Equine Performance Center, Michigan State University, East Lansing, MI, 48823, USA.
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Jain S, Nair G, Nuchin A, Uppe A. Study of the diaphragm in chronic obstructive pulmonary disease using ultrasonography. Lung India 2019; 36:299-303. [PMID: 31290414 PMCID: PMC6625233 DOI: 10.4103/lungindia.lungindia_466_18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Aims and Objectives The study aims to compare the changes in the diaphragm in chronic obstructive pulmonary disease (COPD) patients in Indian population with the help of ultrasound-guided examination. (1) Changes in thickness of the diaphragm during respiration( to rule out diaphragm muscle atrophy). (2) The movement of the diaphragm(correlates with strength and endurance of diaphragm fibres) . (3) Zone of apposition(gives mechanical advantage to diaphragm). (4) Correlation with COPD severity by global initiative for chronic obstructive lung disease (GOLD) staging. Subjects and Methods Forty-eight COPD patients attending OPD of DY Patil Hospital were recruited in the study and twenty age-matched controls were taken. Detailed history, pulmonary function test examination, and diaphragm study under ultrasonography was done. Results The movement of diaphragm was reduced in mild to moderate COPD (A and B) but increased in COPD with Grade C. Movement of diaphragm was significantly more in cases with COPD Grade B (2.329 cm) and C (2.269 cm) as compared to controls (1.891 cm). Mean diaphragmatic thickness during inspiration and expiration, change in thickness, and zone of apposition were significantly higher in patients with COPD score Grade C as compared to Grade A or B. Zone of apposition was significantly decreased in Grade A (3.257 cm) and B (3.429 cm) compared to control (4.268 cm), while it was significantly increased in cases with Grade C (5.138 cm). Conclusion The diaphragm is the main muscle of respiration, and study of diaphragm is very important in COPD. The diaphragm thickness, movement, and zone of apposition were significantly reduced in mild to moderate COPD but increased in severe COPD. This cannot be explained by physiotherapy or collagen accumulation. Hence, diaphragm muscle biopsy and electromyogram study in COPD patients will be required to get a better understanding of this muscle in COPD.
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Affiliation(s)
- Sanket Jain
- Department of Pulmonary Medicine, Dr. DY Patil Medical College, Navi Mumbai, Maharashtra, India
| | - Girija Nair
- Department of Pulmonary Medicine, Dr. DY Patil Medical College, Navi Mumbai, Maharashtra, India
| | - Abhishek Nuchin
- Department of Pulmonary Medicine, Dr. DY Patil Medical College, Navi Mumbai, Maharashtra, India
| | - Abhay Uppe
- Department of Pulmonary Medicine, Dr. DY Patil Medical College, Navi Mumbai, Maharashtra, India
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Lewis P, Sheehan D, Soares R, Coelho AV, O'Halloran KD. Redox Remodeling Is Pivotal in Murine Diaphragm Muscle Adaptation to Chronic Sustained Hypoxia. Am J Respir Cell Mol Biol 2017; 55:12-23. [PMID: 26681636 DOI: 10.1165/rcmb.2015-0272oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mechanisms underpinning chronic sustained hypoxia (CH)-induced structural and functional adaptations in respiratory muscles are unclear despite the clinical relevance to respiratory diseases. The objectives of the present study were to thoroughly assess the putative role of CH-induced redox remodeling in murine diaphragm muscle over time and the subsequent effects on metabolic enzyme activities, catabolic signaling and catabolic processes, and diaphragm muscle contractile function. C57Bl6/J mice were exposed to normoxia or normobaric CH (fraction of inspired oxygen = 0.1) for 1, 3, or 6 weeks. A second cohort was exposed to CH for 6 weeks with and without antioxidant supplementation (tempol or N-acetyl cysteine). After CH exposure, we performed two-dimensional redox proteomics with mass spectrometry, enzyme activity assays, and cell-signaling assays on diaphragm homogenates. We also assessed diaphragm isotonic contractile and endurance properties ex vivo. Global protein redox changes in the diaphragm after CH are indicative of oxidation. Remodeling of proteins key to contractile, metabolic, and homeostatic functions was observed. Several oxidative and glycolytic enzyme activities were decreased by CH. Redox-sensitive chymotrypsin-like proteasome activity of the diaphragm was increased. CH decreased phospho-forkhead box O3a (FOXO3a) and phospho-mammalian target of rapamycin content. Hypoxia-inducible factor-1α and phospho-p38 mitogen-activated protein kinase content was increased in CH diaphragm, and this was attenuated by antioxidant treatment. CH exposure decreased force- and power-generating capacity of the diaphragm, and this was prevented by antioxidant supplementation with N-acetyl cysteine but not tempol. Redox remodeling is pivotal for diaphragm adaptation to CH, affecting metabolic activity, atrophy signaling, and functional performance. Antioxidant supplementation may be useful as an adjunctive therapy in respiratory-related diseases characterized by hypoxic stress.
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Affiliation(s)
| | - David Sheehan
- 2 School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland; and
| | - Renata Soares
- 3 Instituto de Tecnologia Quimica e Biologica António Xavier, Universidade Novade Lisboa, Lisbon, Portugal
| | - Ana Varela Coelho
- 3 Instituto de Tecnologia Quimica e Biologica António Xavier, Universidade Novade Lisboa, Lisbon, Portugal
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Wu J, Zhang JY, Gong Y, Li ST. Slowed relaxation of diaphragm in septic rats is associated with reduced expression of sarco-endoplasmic reticulum CA2+-ATPase genesSERCA1andSERCA2. Muscle Nerve 2016; 54:1108-1113. [PMID: 27104787 DOI: 10.1002/mus.25150] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2016] [Indexed: 01/02/2023]
Affiliation(s)
- Jin Wu
- Department of Anesthesiology, First People's Hospital, School of Medicine; Shanghai Jiaotong University; 100 Hai Ning Road Shanghai 20080 China
| | - Jian You Zhang
- Department of Anesthesiology, First People's Hospital, School of Medicine; Shanghai Jiaotong University; 100 Hai Ning Road Shanghai 20080 China
| | - Yuan Gong
- Department of Anesthesiology, First People's Hospital, School of Medicine; Shanghai Jiaotong University; 100 Hai Ning Road Shanghai 20080 China
| | - Shi Tong Li
- Department of Anesthesiology, First People's Hospital, School of Medicine; Shanghai Jiaotong University; 100 Hai Ning Road Shanghai 20080 China
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Byrne PIBJ, Collins S, Mah CC, Smith B, Conlon T, Martin SD, Corti M, Cleaver B, Islam S, Lawson LA. Phase I/II trial of diaphragm delivery of recombinant adeno-associated virus acid alpha-glucosidase (rAAaV1-CMV-GAA) gene vector in patients with Pompe disease. HUM GENE THER CL DEV 2015; 25:134-63. [PMID: 25238277 DOI: 10.1089/humc.2014.2514] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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8
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Cancelliero-Gaiad KM, Ike D, Costa D. Efeito da estimulação diafragmática elétrica transcutânea em parâmetros respiratórios de pacientes com Doença Pulmonar Obstrutiva Crônica. FISIOTERAPIA E PESQUISA 2013. [DOI: 10.1590/s1809-29502013000400004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
O objetivo do estudo foi avaliar o efeito da estimulação diafragmática elétrica transcutânea (EDET) sobre a força e endurance muscular respiratória, expansibilidade toracoabdominal e variáveis espirométricas de indivíduos com doença pulmonar obstrutiva crônica (DPOC). Oito pacientes com DPOC submetidos à fisioterapia respiratória receberam tratamento com EDET duas vezes por semana durante 06 semanas, totalizando 12 sessões. Antes e depois do tratamento eles foram avaliados pelos seguintes parâmetros: pressão inspiratória máxima (PImáx); pressão expiratória máxima (PEmáx); cirtometria axilar, xifoideana e abdominal; e espirometria. Após o teste Shapiro-Wilk, o teste t de Student pareado e o teste Mann-Whitney foram aplicados para a comparação dos dois estágios (antes e após a EDET). Para a comparação dos estágios antes, após (pós-1a sessão), 1ª, 2ª, 3ª e 4ª semana, a ANOVA seguida do teste de Tukey foram aplicados (p<0,05). De acordo com os resultados obtidos, foi observado que a EDET promoveu aumento significativo em: PImáx (47,3%); PEmáx (21,7%); cirtometria axilar (55,5%); xifoideana (59,2%) e abdominal (74,2%), mas não nas variáveis espirométricas. Na análise longitudinal (nas 4 semanas seguintes) o aumento encontrado na PImáx e na expansibilidade toracoabdominal foi mantido. Assim conclui-se que a EDET promoveu melhora na força muscular respiratória e na expansibilidade toracoabdominal em pacientes com DPOC sem alteração nas variáveis espirométricas; e alguns parâmetros foram mantidos nas quatro semanas seguintes.
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9
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Impact of diaphragm muscle fiber atrophy on neuromotor control. Respir Physiol Neurobiol 2013; 189:411-8. [PMID: 23831121 DOI: 10.1016/j.resp.2013.06.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/26/2013] [Accepted: 06/26/2013] [Indexed: 11/21/2022]
Abstract
In skeletal muscles, motor units comprise a motoneuron and the group of muscle fibers innervated by it, which are usually classified based on myosin heavy chain isoform expression. Motor units displaying diverse contractile and fatigue properties are important in determining the range of motor behaviors that can be accomplished by a muscle. Muscle fiber atrophy and weakness may disproportionately affect specific fiber types across a variety of diseases or clinical conditions, thus impacting neuromotor control. In this regard, fiber atrophy that affects a specific fiber type will alter the relative contribution of different motor units to overall muscle structure and function. For example, in various diseases there is fairly selective atrophy of type IIx and/or IIb fibers comprising the strongest yet most fatigable motor units. As a result, there is muscle weakness (i.e., reductions in force per cross-sectional area) associated with an apparent improvement in resistance to fatiguing contractions. This review will examine neuromotor control of respiratory muscles such as the diaphragm muscle and the impact of muscle fiber atrophy on motor performance.
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10
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Abstract
Neuromotor control of skeletal muscles, including respiratory muscles, is ultimately dependent on the structure and function of the motor units (motoneurons and the muscle fibers they innervate) comprising the muscle. In most muscles, considerable diversity of contractile and fatigue properties exists across motor units, allowing a range of motor behaviors. In diseases such as chronic obstructive pulmonary disease (COPD), there may be disproportional primary (disease related) or secondary effects (related to treatment or other concomitant factors) on the size and contractility of specific muscle fiber types that would influence the relative contribution of different motor units. For example, with COPD there is a disproportionate atrophy of type IIx and/or IIb fibers that comprise more fatigable motor units. Thus fatigue resistance may appear to improve, while overall motor performance (e.g., 6-min walk test) and endurance (e.g., reduced aerobic exercise capacity) are diminished. There are many coexisting factors that might also influence motor performance. For example, in COPD patients, there may be concomitant hypoxia and/or hypercapnia, physical inactivity and unloading of muscles, and corticosteroid treatment, all of which may disproportionately affect specific muscle fiber types, thereby influencing neuromotor control. Future studies should address how plasticity in motor units can be harnessed to mitigate the functional impact of COPD-induced changes.
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Affiliation(s)
- Carlos B Mantilla
- Department of Physiology and Biomedical Engineering, Mayo Clinic, College of Medicine, Rochester, Minnesota 55905, USA
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11
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Puente-Maestu L, Lázaro A, Humanes B. Metabolic derangements in COPD muscle dysfunction. J Appl Physiol (1985) 2013; 114:1282-90. [PMID: 23288549 DOI: 10.1152/japplphysiol.00815.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mitochondrial muscle alterations are common in patients with chronic obstructive pulmonary disease (COPD) and manifest mainly as decreased oxidative capacity and excessive production of reactive oxygen species (ROS). The significant loss of oxidative capacity observed in the quadriceps of COPD patients is mainly due to reduced mitochondrial content in the fibers, a finding consistent with the characteristic loss of type I fibers observed in that muscle. Decreased oxidative capacity does not directly limit maximum performance; however, it is associated with increased lactate production at lower exercise intensity and reduced endurance. Since type I fiber atrophy does not occur in respiratory muscles, the loss of such fibers in the quadriceps could be to the result of disuse. In contrast, excessive production of ROS and oxidative stress are observed in both the respiratory muscles and the quadriceps of COPD patients. The causes of increased ROS production are not clear, and a number of different mechanisms can play a role. Several mitochondrial alterations in the quadriceps of COPD patients are similar to those observed in diabetic patients, thus suggesting a role for muscle alterations in this comorbidity. Amino acid metabolism is also altered. Expression of peroxisome proliferator-activated receptor-γ coactivator-1α mRNA is low in the quadriceps of COPD patients, which could also be a consequence of type I fiber loss; nevertheless, its response to exercise is not altered. Patterns of muscle cytochrome oxidase gene activation after training differ between COPD patients and healthy subjects, and the profile is consistent with hypoxic stress, even in nonhypoxic patients.
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Affiliation(s)
- Luis Puente-Maestu
- Servicio de Neumología, Hospital General Gregorio Marañón, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.
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Levine S, Bashir MH, Clanton TL, Powers SK, Singhal S. COPD elicits remodeling of the diaphragm and vastus lateralis muscles in humans. J Appl Physiol (1985) 2012; 114:1235-45. [PMID: 23264538 DOI: 10.1152/japplphysiol.01121.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A profound remodeling of the diaphragm and vastus lateralis (VL) occurs in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). In this mini-review, we discuss the following costal diaphragm remodeling features noted in patients with moderate-to-severe COPD: 1) deletion of serial sarcomeres, 2) increased proportion of slow-twitch fibers, 3) fast-to-slow isoform shift in sarco(endo)plasmic reticulum Ca(2+)-ATPase, 4) increased capacity of oxidative metabolism, 5) oxidative stress, and 6) myofiber atrophy. We then present the sole feature of diaphragm remodeling noted in mild-to-moderate COPD under the heading "MyHC and contractile remodeling noted in mild-to-moderate COPD." The importance of VL remodeling in COPD patients as a prognostic indicator as well as a major determinant of the ability to carry out activities of daily living is well accepted. We present the remodeling of the VL noted in COPD patients under the following headings: 1) Decrease in proportion of slow-twitch fibers, 2) Decreased activity of oxidative pathways, 3) Oxidative and nitrosative stress, and 4) Myofiber atrophy. For each of the remodeling features noted in both the VL and costal diaphragm of COPD patients, we present mechanisms that are currently thought to mediate these changes as well as the pathophysiology of each remodeling feature. We hope that our mechanistic presentation stimulates research in this area that focuses on improving the ability of COPD patients to carry out increased activities of daily living.
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Affiliation(s)
- Sanford Levine
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19035, USA.
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13
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Tang H, Lee M, Budak MT, Pietras N, Hittinger S, Vu M, Khuong A, Hoang CD, Hussain SNA, Levine S, Shrager JB. Intrinsic apoptosis in mechanically ventilated human diaphragm: linkage to a novel Fos/FoxO1/Stat3-Bim axis. FASEB J 2011; 25:2921-36. [PMID: 21597002 DOI: 10.1096/fj.11-183798] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mechanical ventilation (MV) is a life-saving measure in many critically ill patients. However, prolonged MV results in diaphragm dysfunction that contributes to the frequent difficulty in weaning patients from the ventilator. The molecular mechanisms underlying ventilator-induced diaphragm dysfunction (VIDD) remain poorly understood. We report here that MV induces myonuclear DNA fragmentation (3-fold increase; P<0.01) and selective activation of caspase 9 (P<0.05) and Bcl2-interacting mediator of cell death (Bim; 2- to 7-fold increase; P<0.05) in human diaphragm. MV also statistically significantly down-regulates mitochondrial gene expression and induces oxidative stress. In cultured muscle cells, we show that oxidative stress activates each of the catabolic pathways thought to underlie VIDD: apoptotic (P<0.05), proteasomal (P<0.05), and autophagic (P<0.01). Further, silencing Bim expression blocks (P<0.05) oxidative stress-induced apoptosis. Overlapping the gene expression profiles of MV human diaphragm and H₂O₂-treated muscle cells, we identify Fos, FoxO1, and Stat3 as regulators of Bim expression as well as of expression of the catabolic markers atrogin and LC3. We thus identify a novel Fos/FoxO1/Stat3-Bim intrinsic apoptotic pathway and establish the centrality of oxidative stress in the development of VIDD. This information may help in the design of specific drugs to prevent this condition.
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Affiliation(s)
- Huibin Tang
- Division of Thoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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14
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Clanton TL, Levine S. Respiratory muscle fiber remodeling in chronic hyperinflation: dysfunction or adaptation? J Appl Physiol (1985) 2009; 107:324-35. [PMID: 19359619 DOI: 10.1152/japplphysiol.00173.2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The diaphragm and other respiratory muscles undergo extensive remodeling in both animal models of emphysema and in human chronic obstructive pulmonary disease, but the nature of the remodeling is different in many respects. One common feature is a shift toward improved endurance characteristics and increased oxidative capacity. Furthermore, both animals and humans respond to chronic hyperinflation by diaphragm shortening. Although in rodent models this clearly arises by deletion of sarcomeres in series, the mechanism has not been proven conclusively in human chronic obstructive pulmonary disease. Unique characteristics of the adaptation in human diaphragms include shifts to more predominant slow, type I fibers, expressing slower myosin heavy chain isoforms, and type I and type II fiber atrophy. Although some laboratories report reductions in specific force, this may be accounted for by decreases in myosin heavy chain content as the muscles become more oxidative and more efficient. More recent findings have reported reductions in Ca(2+) sensitivity and reduced myofibrillar elastic recoil. In contrast, in rodent models of disease, there is no consistent evidence for loss of specific force, no consistent shift in fiber populations, and atrophy is predominantly seen only in fast, type IIX fibers. This review challenges the hypothesis that the adaptations in human diaphragm represent a form of dysfunction, secondary to systemic disease, and suggest that most findings can as well be attributed to adaptive processes of a complex muscle responding to unique alterations in its working environment.
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Affiliation(s)
- Thomas L Clanton
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida 32611, USA.
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15
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Green HJ, Burnett M, Duhamel TA, D'Arsigny C, O'Donnell DE, Webb KA, Ouyang J. Abnormal sarcoplasmic reticulum Ca2+-sequestering properties in skeletal muscle in chronic obstructive pulmonary disease. Am J Physiol Cell Physiol 2008; 295:C350-7. [DOI: 10.1152/ajpcell.00224.2008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to investigate the hypothesis that alterations in sarcoplasmic reticulum (SR) Ca2+-cycling properties would occur in skeletal muscle in patients with moderate to severe chronic obstructive pulmonary disease (COPD). To investigate this hypothesis, tissue samples were obtained from the vastus lateralis of 8 patients with COPD [age 65.6 ± 3.2 yr; forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) = 44 ± 2%; mean ± SE] and 10 healthy age-matched controls (CON, age 67.5 ± 2.5 yr; FEV1/FVC = 77 ± 2%), and homogenates were analyzed for a wide range of SR properties. Compared with CON, COPD displayed (in μmol·g protein−1·min−1) a 16% lower maximal Ca2+-ATPase activity [maximal velocity ( Vmax), 158 ± 10 vs. 133 ± 7, P < 0.05] and a 17% lower Ca2+uptake (4.65 ± 0.039 vs. 3.85 ± 0.26, P < 0.05) that occurred in the absence of differences in Ca2+release. The lower Vmaxin COPD was also accompanied by an 11% lower ( P < 0.05) Ca2+sensitivity, as measured by the Hill coefficient (defined as the relationship between Ca2+-ATPase activity and free cytosolic Ca2+concentration for 10–90% Vmax). For the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) isoforms, SERCA1a was 16% higher ( P < 0.05) and SERCA2a was 14% lower ( P < 0.05) in COPD. It is concluded that moderate to severe COPD results in abnormalities in SR Ca2+-ATPase properties that cannot be explained by changes in the SERCA isoform phenotypes. The reduced catalytic properties of SERCA in COPD suggest a disturbance in Ca2+cycling, possibly resulting in impairment in Ca2+-mediated mechanical function and/or second messenger regulated processes.
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Ottenheijm CAC, Heunks LMA, Dekhuijzen RPN. Diaphragm adaptations in patients with COPD. Respir Res 2008; 9:12. [PMID: 18218129 PMCID: PMC2248576 DOI: 10.1186/1465-9921-9-12] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2007] [Accepted: 01/24/2008] [Indexed: 01/03/2023] Open
Abstract
Inspiratory muscle weakness in patients with COPD is of major clinical relevance. For instance, maximum inspiratory pressure generation is an independent determinant of survival in severe COPD. Traditionally, inspiratory muscle weakness has been ascribed to hyperinflation-induced diaphragm shortening. However, more recently, invasive evaluation of diaphragm contractile function, structure, and biochemistry demonstrated that cellular and molecular alterations occur, of which several can be considered pathologic of nature. Whereas the fiber type shift towards oxidative type I fibers in COPD diaphragm is regarded beneficial, rendering the overloaded diaphragm more resistant to fatigue, the reduction of diaphragm fiber force generation in vitro likely contributes to diaphragm weakness. The reduced diaphragm force generation at single fiber level is associated with loss of myosin content in these fibers. Moreover, the diaphragm in COPD is exposed to oxidative stress and sarcomeric injury. This review postulates that the oxidative stress and sarcomeric injury activate proteolytic machinery, leading to contractile protein wasting and, consequently, loss of force generating capacity of diaphragm fibers in patients with COPD. Interestingly, several of these presumed pathologic alterations are already present early in the course of the disease (GOLD I/II), although these patients appear not limited in their daily life activities. Treatment of diaphragm dysfunction in COPD is complex since its etiology is unclear, but recent findings indicate the ubiquitin-proteasome pathway as a prime target to attenuate diaphragm wasting in COPD.
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Affiliation(s)
- Coen A C Ottenheijm
- Dept. of Molecular and Cellular Biology, University of Arizona, Tucson, USA.
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Ottenheijm CAC, Heunks LMA, Dekhuijzen PNR. Diaphragm muscle fiber dysfunction in chronic obstructive pulmonary disease: toward a pathophysiological concept. Am J Respir Crit Care Med 2007; 175:1233-40. [PMID: 17413128 DOI: 10.1164/rccm.200701-020pp] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Inspiratory muscle weakness in patients with chronic obstructive pulmonary disease (COPD) is of major clinical relevance; maximum inspiratory pressure generation is an independent determinant of survival in severe COPD. Traditionally, inspiratory muscle weakness has been ascribed to hyperinflation-induced diaphragm shortening. However, more recently, invasive evaluation of diaphragm contractile function, structure, and biochemistry demonstrated that cellular and molecular alterations occur, of which several can be considered of pathologic nature. Although the fiber-type shift toward oxidative type I fibers in COPD diaphragm is regarded as beneficial, rendering the overloaded diaphragm more resistant to fatigue, the reduction of diaphragm fiber force generation in vitro likely contributes to diaphragm weakness. The reduced diaphragm force generation at single-fiber level is associated with loss of myosin content. Moreover, the diaphragm in COPD is exposed to oxidative stress and sarcomeric injury. The current Pulmonary Perspective postulates that the oxidative stress and sarcomeric injury activate proteolytic machinery, leading to contractile protein wasting and, consequently, loss of force-generating capacity of diaphragm fibers in patients with COPD. Interestingly, several of these presumed pathologic alterations are already present early in the course of the disease (GOLD I/II), although these patients do not appear to be limited in their daily-life activities. Therefore, investigating in vivo diaphragm function in mild to moderate COPD should be the focus of future research. Treatment of diaphragm dysfunction in COPD is complex because its etiology is unclear, but recent findings show promise for the use of proteasome inhibitors in syndromes associated with muscle wasting, such as the diaphragm in COPD.
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Affiliation(s)
- Coen A C Ottenheijm
- Department of Pulmonary Diseases, 454 Radboud University, Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
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Levine S, Nguyen T, Friscia M, Zhu J, Szeto W, Kucharczuk JC, Tikunov BA, Rubinstein NA, Kaiser LR, Shrager JB. Parasternal intercostal muscle remodeling in severe chronic obstructive pulmonary disease. J Appl Physiol (1985) 2006; 101:1297-302. [PMID: 16777998 DOI: 10.1152/japplphysiol.01607.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Studies in experimental animals indicate that chronic increases in neural drive to limb muscles elicit a fast-to-slow transformation of fiber-type proportions and myofibrillar proteins. Since neural drive to the parasternal intercostal muscles (parasternals) is chronically increased in patients with severe chronic obstructive pulmonary diseases (COPDs), we carried out the present study to test the hypothesis that the parasternals of COPD patients exhibit an increase in the proportions of both slow fibers and slow myosin heavy chains (MHCs). Accordingly, we obtained full thickness parasternal muscle biopsies from the third interspace of seven COPD patients (mean +/- SE age: 59 +/- 4 yr) and seven age-matched controls (AMCs). Fiber typing was done by immunohistochemistry, and MHC proportions were determined by SDS-PAGE followed by densitometry. COPD patients exhibited higher proportions of slow fibers than AMCs (73 +/- 4 vs. 51 +/- 3%; P < 0.01). Additionally, COPD patients exhibited higher proportions of slow MHC than AMCs (56 +/- 4 vs. 46 +/- 4%, P < 0.04). We conclude that the parasternal muscles of patients with severe COPD exhibit a fast-to-slow transformation in both fiber-type and MHC proportions. Previous workers have demonstrated that remodeling of the external intercostals, another rib cage inspiratory muscle, elicited by severe COPD is characterized by a slow-to-fast transformation in both fiber types and MHC isoform proportions. The physiological significance of this difference in remodeling between these two inspiratory rib cage muscles remains to be elucidated.
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MESH Headings
- Biomarkers/analysis
- Biomarkers/metabolism
- Densitometry
- Diaphragm/chemistry
- Diaphragm/metabolism
- Diaphragm/pathology
- Electrophoresis, Polyacrylamide Gel
- Fluorescent Antibody Technique, Indirect
- Humans
- Intercostal Muscles/chemistry
- Intercostal Muscles/metabolism
- Intercostal Muscles/pathology
- Middle Aged
- Muscle Fibers, Fast-Twitch/chemistry
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Fast-Twitch/pathology
- Muscle Fibers, Slow-Twitch/chemistry
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/pathology
- Myofibrils/metabolism
- Myofibrils/pathology
- Myosin Heavy Chains/analysis
- Myosin Heavy Chains/metabolism
- Pulmonary Disease, Chronic Obstructive/metabolism
- Pulmonary Disease, Chronic Obstructive/pathology
- Pulmonary Disease, Chronic Obstructive/physiopathology
- Respiratory Function Tests
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Affiliation(s)
- Sanford Levine
- Department of Surgery, Division of Thoracic Surgery, University of Pennsylvania, Philadelphia, PA 19104-4283, USA.
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