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Xu X, Wen Z. The mediating role of inflammaging between mitochondrial dysfunction and sarcopenia in aging: a review. AMERICAN JOURNAL OF CLINICAL AND EXPERIMENTAL IMMUNOLOGY 2023; 12:109-126. [PMID: 38187366 PMCID: PMC10767199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 11/26/2023] [Indexed: 01/09/2024]
Abstract
Sarcopenia, characterized by the insidious reduction of skeletal muscle mass and strength, detrimentally affects the quality of life in elderly cohorts. Present therapeutic strategies are confined to physiotherapeutic interventions, signaling a critical need for elucidation of the etiological underpinnings to facilitate the development of innovative pharmacotherapies. Recent scientific inquiries have associated mitochondrial dysfunction and inflammation with the etiology of sarcopenia. Mitochondria are integral to numerous fundamental cellular processes within muscle tissue, including but not limited to apoptosis, autophagy, signaling via reactive oxygen species, and the maintenance of protein equilibrium. Deviations in mitochondrial dynamics, coupled with compromised oxidative capabilities, autophagic processes, and protein equilibrium, result in disturbances to muscular architecture and functionality. Mitochondrial dysfunction is particularly detrimental as it diminishes oxidative phosphorylation, escalates apoptotic activity, and hinders calcium homeostasis within muscle cells. Additionally, deleterious feedback loops of deteriorated respiration, exacerbated oxidative injury, and diminished quality control mechanisms precipitate the acceleration of muscular senescence. Notably, mitochondria exhibiting deficient energetic metabolism are pivotal in precipitating the shift from normative muscle aging to a pathogenic state. This analytical review meticulously examines the complex interplay between mitochondrial dysfunction, persistent inflammation, and the pathogenesis of sarcopenia. It underscores the imperative to alleviate inflammation and amend mitochondrial anomalies within geriatric populations as a strategy to forestall and manage sarcopenia. An initial overview provides a succinct exposition of sarcopenia and its clinical repercussions. The discourse then progresses to an examination of the direct correlation between mitochondrial dysfunction and the genesis of sarcopenia. Concomitantly, it accentuates potential synergistic effects between inflammatory responses and mitochondrial insufficiencies during the aging of skeletal muscle, thereby casting light upon emergent therapeutic objectives. In culmination, this review distills the prevailing comprehension of the mitochondrial and inflammatory pathways implicated in sarcopenia and delineates extant lacunae in knowledge to orient subsequent scientific inquiry.
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Affiliation(s)
- Xin Xu
- Department of Rehabilitation Therapy, School of Health, Shanghai Normal University Tianhua CollegeShanghai, China
| | - Zixing Wen
- Department of Rehabilitation, School of International Medical Technology, Shanghai Sanda UniversityShanghai, China
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An energetics perspective on geroscience: mitochondrial protonmotive force and aging. GeroScience 2021; 43:1591-1604. [PMID: 33864592 DOI: 10.1007/s11357-021-00365-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/07/2021] [Indexed: 12/13/2022] Open
Abstract
Mitochondria are organelles that provide energy to cells through ATP production. Mitochondrial dysfunction has long been postulated to mediate cellular declines that drive biological aging. Many well-characterized hallmarks of aging may involve underlying energetic defects that stem from loss of mitochondrial function with age. Why and how mitochondrial function declines with age is an open question and one that has been difficult to answer. Mitochondria are powered by an electrochemical gradient across the inner mitochondrial membrane known as the protonmotive force (PMF). This gradient decreases with age in several experimental models. However, it is unclear if a diminished PMF is a cause or a consequence of aging. Herein, we briefly review and define mitochondrial function, we summarize how PMF changes with age in several models, and we highlight recent studies that implicate PMF in aging biology. We also identify barriers that must be addressed for the field to progress. Emerging technology permits more precise in vivo study of mitochondria that will allow better understanding of cause and effect in metabolic models of aging. Once cause and effect can be discerned more precisely, energetics approaches to combat aging may be developed to prevent or reverse functional decline.
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Ravussin E, Smith SR, Ferrante AW. Physiology of Energy Expenditure in the Weight-Reduced State. Obesity (Silver Spring) 2021; 29 Suppl 1:S31-S38. [PMID: 33759394 PMCID: PMC8988211 DOI: 10.1002/oby.23095] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/23/2020] [Accepted: 11/25/2020] [Indexed: 11/10/2022]
Abstract
Although many individuals achieve weight loss of 10% or more, the ability to maintain a reduced body mass over months and years is much rarer. Unfortunately, our understanding of the adverse consequences of having overweight and obesity argues that long-term maintenance of a reduced weight provides the greatest health benefit. However, to achieve long-term weight reduction requires overcoming neuroendocrine systems that favor restoration of one's initial weight. Identifying and characterizing the components of these systems will be important if we are to develop therapies and strategies to reduce the rates of obesity and its complications in our modern society. During this session, Eric Ravussin and Steven R. Smith, respectively, discussed the physiology of the weight-reduced state that favors weight regain and a molecular component that contributes to this response.
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Affiliation(s)
- Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
| | | | - Anthony W. Ferrante
- Naomi Berrie Diabetes Center, Vagelos College of Physicians & Surgeons, Columbia University, New York, New York, USA
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Darpolor MM, Singh M, Covington J, Hanet S, Ravussin E, Carmichael OT. Molecular correlates of MRS-based 31 phosphocreatine muscle resynthesis rate in healthy adults. NMR IN BIOMEDICINE 2021; 34:e4402. [PMID: 32875687 PMCID: PMC8491428 DOI: 10.1002/nbm.4402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 07/25/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
Dynamic phosphorus MRS (31 P-MRS) is a method used for in vivo studies of skeletal muscle energetics including measurements of phosphocreatine (PCr) resynthesis rate during recovery of submaximal exercise. However, the molecular events associated with the PCr resynthesis rate are still under debate. We assessed vastus lateralis PCr resynthesis rate from 31 P-MRS spectra collected from healthy adults as part of the CALERIE II study (caloric restriction), and assessed associations between PCr resynthesis and muscle mitochondrial signature transcripts and proteins (NAMPT, NQO1, PGC-1α, and SIRT1). Regression analysis indicated that higher concentration of nicotinamide phosphoribosyltransferase (NAMPT) protein, a mitochondrial capacity marker, was associated with faster PCr resynthesis. However, PCr resynthesis was not associated with greater physical fitness (VO2 peak) or messenger ribonucleic acid levels of mitochondrial function markers such as NQO1, PGC-1α, and SIRT1, suggesting that the impact of these molecular signatures on PCr resynthesis may be minimal in the context of an acute exercise bout. Together, these findings suggest that 31 P-MRS based PCr resynthesis may represent a valid non-invasive surrogate marker of mitochondrial NAMPT in human skeletal muscle.
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Affiliation(s)
- Moses M Darpolor
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Maninder Singh
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Jeffrey Covington
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Sebastian Hanet
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Eric Ravussin
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Owen T Carmichael
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
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Dent R, McPherson R, Harper ME. Factors affecting weight loss variability in obesity. Metabolism 2020; 113:154388. [PMID: 33035570 DOI: 10.1016/j.metabol.2020.154388] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/19/2020] [Accepted: 09/23/2020] [Indexed: 12/25/2022]
Abstract
Current obesity treatment strategies include diet, exercise, bariatric surgery, and a limited but growing repertoire of medications. Individual weight loss in response to each of these strategies is highly variable. Here we review research into factors potentially contributing to inter-individual variability in response to treatments for obesity, with a focus on studies in humans. Well-recognized factors associated with weight loss capacity include diet adherence, physical activity, sex, age, and specific medications. However, following control for each of these, differences in weight loss appear to persist in response to behavioral, pharmacological and surgical interventions. Adaptation to energy deficit involves complex feedback mechanisms, and inter-individual differences likely to arise from a host of poorly defined genetic factors, as well as differential responses in neurohormonal mechanisms (including gastrointestinal peptides), metabolic efficiency and capacity of tissues, non-exercise activity thermogenesis, thermogenic response to food, and in gut microbiome. A better understanding of the factors involved in inter-individual variability in response to therapies will guide more personalized approaches to the treatment of obesity.
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Affiliation(s)
- Robert Dent
- Department of Medicine, Division of Endocrinology and The Ottawa Hospital, University of Ottawa, 210 Melrose Ave, Ottawa, ON K1Y 4K7, Canada
| | - Ruth McPherson
- Atherogenomics Laboratory, Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON K1Y 4W7, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Rd., Ottawa, ON K1H 8M5, Canada.
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Myoepithelial cell-driven acini contraction in response to oxytocin receptor stimulation is impaired in lacrimal glands of Sjögren's syndrome animal models. Sci Rep 2018; 8:9919. [PMID: 29967327 PMCID: PMC6028591 DOI: 10.1038/s41598-018-28227-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 06/19/2018] [Indexed: 02/08/2023] Open
Abstract
The purpose of the present studies was to investigate the impact of chronic inflammation of the lacrimal gland, as occurs in Sjögren’s syndrome, on the morphology and function of myoepithelial cells (MECs). In spite of the importance of MECs for lacrimal gland function, the effect of inflammation on MECs has not been well defined. We studied changes in MEC structure and function in two animal models of aqueous deficient dry eye, NOD and MRL/lpr mice. We found a statistically significant reduction in the size of MECs in diseased compared to control lacrimal glands. We also found that oxytocin receptor was highly expressed in MECs of mouse and human lacrimal glands and that its expression was strongly reduced in diseased glands. Furthermore, we found a significant decrease in the amount of two MEC contractile proteins, α-smooth muscle actin (SMA) and calponin. Finally, oxytocin-mediated contraction was impaired in lacrimal gland acini from diseased glands. We conclude that chronic inflammation of the lacrimal gland leads to a substantial thinning of MECs, down-regulation of contractile proteins and oxytocin receptor expression, and therefore impaired acini contraction. This is the first study highlighting the role of oxytocin mediated MEC contraction on lacrimal gland function.
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Sparks LM, Redman LM, Conley KE, Harper ME, Yi F, Hodges A, Eroshkin A, Costford SR, Gabriel ME, Shook C, Cornnell HH, Ravussin E, Smith SR. Effects of 12 Months of Caloric Restriction on Muscle Mitochondrial Function in Healthy Individuals. J Clin Endocrinol Metab 2017; 102:111-121. [PMID: 27778643 PMCID: PMC5413108 DOI: 10.1210/jc.2016-3211] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 10/21/2016] [Indexed: 11/19/2022]
Abstract
CONTEXT The effects of caloric restriction (CR) on in vivo muscle mitochondrial function in humans are controversial. OBJECTIVE We evaluated muscle mitochondrial function and associated transcriptional profiles in nonobese humans after 12 months of CR. DESIGN Individuals from an ancillary study of the CALERIE 2 randomized controlled trial were assessed at baseline and 12 months after a 25% CR or ad libitum (control) diet. SETTING The study was performed at Pennington Biomedical Research Center in Baton Rouge, LA. PARTICIPANTS Study participants included 51 (34 female subjects, 25 to 50 years of age) healthy nonobese individuals randomized to 1 of 2 groups (CR or control). INTERVENTION This study included 12 months of a 25% CR or ad libitum (control) diet. MAIN OUTCOMES In vivo mitochondrial function [maximal ATP synthesis rate (ATPmax), ATPflux/O2 (P/O)] was determined by 31P-magnetic resonance spectroscopy and optical spectroscopy, and body composition was determined by dual-energy X-ray absorptiometry. In a subset of individuals, a muscle biopsy was performed for transcriptional profiling via quantitative reverse transcription polymerase chain reaction and microarrays. RESULTS Weight, body mass index (BMI), fat, and fat-free mass (P < 0.001 for all) significantly decreased at month 12 after CR vs control. In vivo ATPmax and P/O were unaffected by 12 months of CR. Targeted transcriptional profiling showed no effects on pathways involved in mitochondrial biogenesis, function, or oxidative stress. A subgroup analysis according to baseline P/O demonstrated that a higher (vs lower) P/O was associated with notable improvements in ATPmax and P/O after CR. CONCLUSIONS In healthy nonobese humans, CR has no effect on muscle mitochondrial function; however, having a "more coupled" (versus "less coupled") phenotype enables CR-induced improvements in muscle mitochondrial function.
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Affiliation(s)
- Lauren M. Sparks
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804;
- Clinical and Molecular Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827;
| | - Leanne M. Redman
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808;
| | - Kevin E. Conley
- Radiology,
- Physiology & Biophysics, and
- Bioengineering, University of Washington Medical Center, Seattle, Washington 98195;
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario ON K1N 6N5, Canada;
| | - Fanchao Yi
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804;
| | - Andrew Hodges
- Bioinformatics Core, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037; and
| | - Alexey Eroshkin
- Bioinformatics Core, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037; and
| | | | - Meghan E. Gabriel
- Clinical and Molecular Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827;
| | - Cherie Shook
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804;
| | - Heather H. Cornnell
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804;
| | - Eric Ravussin
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808;
| | - Steven R. Smith
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804;
- Clinical and Molecular Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827;
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