Article first published online:  13 November 2019

Wai W. Cheung, Sheng Hao, Zhen Wang, Wei Ding, Ronghao Zheng, Alex Gonzalez, Jian‐Ying Zhan, Ping Zhou, Shiping Li, Mary C. Esparza, Hal M. Hoffman, Richard L. Lieber, Robert H. Mak

Vitamin D repletion ameliorates adipose tissue browning and muscle wasting in infantile nephropathic cystinosis‐associated cachexia
Background
Ctns−/− mice, a mouse model of infantile nephropathic cystinosis, exhibit hypermetabolism with adipose tissue browning and profound muscle wasting. Ctns−/− mice are 25(OH)D3 and 1,25(OH)2D3 insufficient. We investigated whether vitamin D repletion could ameliorate adipose tissue browning and muscle wasting in Ctns−/− mice.
Methods
Twelve‐month‐old Ctns−/− mice and wild‐type controls were treated with 25(OH)D3 and 1,25(OH)2D3 (75 μg/kg/day and 60 ng/kg/day, respectively) or an ethylene glycol vehicle for 6 weeks. Serum chemistry and parameters of energy homeostasis were measured. We quantitated total fat mass and studied expression of molecules regulating adipose tissue browning, energy metabolism, and inflammation. We measured lean mass content, skeletal muscle fibre size, in vivo muscle function (grip strength and rotarod activity), and expression of molecules regulating muscle metabolism. We also analysed the transcriptome of skeletal muscle in Ctns−/− mice using RNAseq.
Results
Supplementation of 25(OH)D3 and 1,25(OH)2D3 normalized serum concentration of 25(OH)D3 and 1,25(OH)2D3 in Ctns−/− mice, respectively. Repletion of vitamin D partially or fully normalized food intake, weight gain, gain of fat, and lean mass, improved energy homeostasis, and attenuated perturbations of uncoupling proteins and adenosine triphosphate content in adipose tissue and muscle in Ctns−/− mice. Vitamin D repletion attenuated elevated expression of beige adipose cell biomarkers (UCP‐1, CD137, Tmem26, and Tbx1) as well as aberrant expression of molecules implicated in adipose tissue browning (Cox2, Pgf2α, and NF‐κB pathway) in inguinal white adipose tissue in Ctns−/− mice. Vitamin D repletion normalized skeletal muscle fibre size and improved in vivo muscle function in Ctns−/− mice. This was accompanied by correcting the increased muscle catabolic signalling (increased protein contents of IL‐1β, IL‐6, and TNF‐α as well as an increased gene expression of Murf‐2, atrogin‐1, and myostatin) and promoting the decreased muscle regeneration and myogenesis process (decreased gene expression of Igf1, Pax7, and MyoD) in skeletal muscles of Ctns−/− mice. Muscle RNAseq analysis revealed aberrant gene expression profiles associated with reduced muscle and neuron regeneration, increased energy metabolism, and fibrosis in Ctns−/− mice. Importantly, repletion of 25(OH)D3 and 1,25(OH)2D3 normalized the top 20 differentially expressed genes in Ctns−/− mice.
Conclusions
We report the novel findings that correction of 25(OH)D3 and 1,25(OH)2D3 insufficiency reverses cachexia and may improve quality of life by restoring muscle function in an animal model of infantile nephropathic cystinosis. Mechanistically, vitamin D repletion attenuates adipose tissue browning and muscle wasting in Ctns−/− mice via multiple cellular and molecular mechanisms.

Cheung, W. W., Hao, S., Wang, Z., Ding, W., Zheng, R., Gonzalez, A., Zhan, J.‐Y., Zhou, P., Li, S., Esparza, M. C., Hoffman, H. M., Lieber, R. L., and Mak, R. H. ( 2019) Vitamin D repletion ameliorates adipose tissue browning and muscle wasting in infantile nephropathic cystinosis‐associated cachexia, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12497.

ABSTRACT | PDF |

 

     Article first published online:  13 November 2019

Thomas Kunzke, Achim Buck, Verena M. Prade, Annette Feuchtinger, Olga Prokopchuk, Marc E. Martignoni, Simone Heisz, Hans Hauner, Klaus‐Peter Janssen, Axel Walch, Michaela Aichler

Derangements of amino acids in cachectic skeletal muscle are caused by mitochondrial dysfunction
Background
Cachexia is the direct cause of at least 20% of cancer‐associated deaths. Muscle wasting in skeletal muscle results in weakness, immobility, and death secondary to impaired respiratory muscle function. Muscle proteins are massively degraded in cachexia; nevertheless, the molecular mechanisms related to this process are poorly understood. Previous studies have reported conflicting results regarding the amino acid abundances in cachectic skeletal muscle tissues. There is a clear need to identify the molecular processes of muscle metabolism in the context of cachexia, especially how different types of molecules are involved in the muscle wasting process.
Methods
New in situ ‐omics techniques were used to produce a more comprehensive picture of amino acid metabolism in cachectic muscles by determining the quantities of amino acids, proteins, and cellular metabolites. Using matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry imaging, we determined the in situ concentrations of amino acids and proteins, as well as energy and other cellular metabolites, in skeletal muscle tissues from genetic mouse cancer models (n = 21) and from patients with cancer (n = 6). Combined results from three individual MALDI mass spectrometry imaging methods were obtained and interpreted. Immunohistochemistry staining for mitochondrial proteins and myosin heavy chain expression, digital image analysis, and transmission electron microscopy complemented the MALDI mass spectrometry imaging results.
Results
Metabolic derangements in cachectic mouse muscle tissues were detected, with significantly increased quantities of lysine, arginine, proline, and tyrosine (P = 0.0037, P = 0.0048, P = 0.0430, and P = 0.0357, respectively) and significantly reduced quantities of glutamate and aspartate (P = 0.0008 and P = 0.0124). Human skeletal muscle tissues revealed similar tendencies. A majority of altered amino acids were released by the breakdown of proteins involved in oxidative phosphorylation. Decreased energy charge was observed in cachectic muscle tissues (P = 0.0101), which was related to the breakdown of specific proteins. Additionally, expression of the cationic amino acid transporter CAT1 was significantly decreased in the mitochondria of cachectic mouse muscles (P = 0.0133); this decrease may play an important role in the alterations of cationic amino acid metabolism and decreased quantity of glutamate observed in cachexia.
Conclusions
Our results suggest that mitochondrial dysfunction has a substantial influence on amino acid metabolism in cachectic skeletal muscles, which appears to be triggered by diminished CAT1 expression, as well as the degradation of mitochondrial proteins. These findings provide new insights into the pathobiochemistry of muscle wasting.

Kunzke, T., Buck, A., Prade, V. M., Feuchtinger, A., Prokopchuk, O., Martignoni, M. E., Heisz, S., Hauner, H., Janssen, K.‐P., Walch, A., and Aichler, M. ( 2019) Derangements of amino acids in cachectic skeletal muscle are caused by mitochondrial dysfunction, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12498.

ABSTRACT | PDF |

 

     Article first published online:  07 November

Alexander S. Ham, Kathrin Chojnowska, Lionel A. Tintignac, Shuo Lin, Alexander Schmidt, Daniel J. Ham, Michael Sinnreich, Markus A. Rüegg

mTORC1 signalling is not essential for the maintenance of muscle mass and function in adult sedentary mice
Background
The balance between protein synthesis and degradation (proteostasis) is a determining factor for muscle size and function. Signalling via the mammalian target of rapamycin complex 1 (mTORC1) regulates proteostasis in skeletal muscle by affecting protein synthesis and autophagosomal protein degradation. Indeed, genetic inactivation of mTORC1 in developing and growing muscle causes atrophy resulting in a lethal myopathy. However, systemic dampening of mTORC1 signalling by its allosteric inhibitor rapamycin is beneficial at the organismal level and increases lifespan. Whether the beneficial effect of rapamycin comes at the expense of muscle mass and function is yet to be established.
Methods
We conditionally ablated the gene coding for the mTORC1‐essential component raptor in muscle fibres of adult mice [inducible raptor muscle‐specific knockout (iRAmKO)]. We performed detailed phenotypic and biochemical analyses of iRAmKO mice and compared them with muscle‐specific raptor knockout (RAmKO) mice, which lack raptor in developing muscle fibres. We also used polysome profiling and proteomics to assess protein translation and associated signalling in skeletal muscle of iRAmKO mice.
Results
Analysis at different time points reveal that, as in RAmKO mice, the proportion of oxidative fibres decreases, but slow‐type fibres increase in iRAmKO mice. Nevertheless, no significant decrease in body and muscle mass or muscle fibre area was detected up to 5 months post‐raptor depletion. Similarly, ex vivo muscle force was not significantly reduced in iRAmKO mice. Despite stable muscle size and function, inducible raptor depletion significantly reduced the expression of key components of the translation machinery and overall translation rates.
Conclusions
Raptor depletion and hence complete inhibition of mTORC1 signalling in fully grown muscle leads to metabolic and morphological changes without inducing muscle atrophy even after 5 months. Together, our data indicate that maintenance of muscle size does not require mTORC1 signalling, suggesting that rapamycin treatment is unlikely to negatively affect muscle mass and function.

Ham, A. S., Chojnowska, K., Tintignac, L. A., Lin, S., Schmidt, A., Ham, D. J., Sinnreich, M., and Rüegg, M. A. ( 2019) mTORC1 signalling is not essential for the maintenance of muscle mass and function in adult sedentary mice, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12505.

ABSTRACT | PDF |

 

     Article first published online:  06 November 2019

Louise Daly, Ross Dolan, Derek Power, Éadaoin Ní Bhuachalla, Wei Sim, Marie Fallon, Samantha Cushen, Claribel Simmons, Donald C. McMillan, Barry J. Laird, Aoife Ryan

The relationship between the BMI‐adjusted weight loss grading system and quality of life in patients with incurable cancer

Background
Weight loss (WL) has long been recognized as an important factor associated with reduced quality of life (QoL) and reduced survival in patients with cancer. The body mass index (BMI)‐adjusted weight loss grading system (WLGS) has been shown to be associated with reduced survival. However, its impact on QoL has not been established. The aim of this study was to assess the relationship between this WLGS and QoL in patients with advanced cancer.
Methods
A biobank analysis was undertaken of adult patients with advanced cancer. Data collected included patient demographics, Eastern Cooperative Oncology Group performance status, and anthropometric parameters (BMI and %WL). Patients were categorized according to the BMI‐adjusted WLGS into one of five distinct WL grades (grades 0–4). QoL was collected using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire‐C30. The Kruskal–Wallis test and multivariate logistic regression analyses were used to assess the relationship between the WLGS and QoL scores. Overall survival was assessed using Kaplan–Meier curve and Cox proportional hazard models.
Results
A total of 1027 patients were assessed (51% male, median age: 66 years). Gastrointestinal cancer was most prevalent (40%), and 87% of patients had metastatic disease. Half (58%) of patients had a WL grade of 0–1, while 12%, 20%, and 10% had WL grades of 2, 3, and 4, respectively. Increasing WL grades were significantly associated with poorer QoL functioning and symptoms scales (all P < 0.05). Physical, role, and emotional functioning decreased by a median of >20 points between WL grade 0 and WL grade 4, while appetite loss, pain, dyspnoea, and fatigue increased by a median score >20 points, indicative of a large clinical significant difference. Increasing WL grades were associated with deteriorating QoL summary score. WL grades 2, 3, and 4 were independently associated with a QoL summary score below the median (<77.7) [odds ratio (OR) 1.69, P = 0.034; OR 2.06, P = 0.001; OR 4.29, P < 0.001, respectively]. WL grades 3 and 4 were independently associated with reduced overall survival [hazard ratio 1.54 (95% confidence interval: 1.22–1.93), P < 0.001 and hazard ratio 1.87 (95% confidence interval: 1.42–2.45), P < 0.001, respectively].
Conclusions
Our findings support that the WLGS is useful in identifying patients at risk of poor QoL that deteriorates with increasing WL grades. WL grade 4 is independently associated with a particularly worse prognosis and increased symptom burden. Identification and early referral to palliative care services may benefit these patients.

Daly, L., Dolan, R., Power, D., Ní Bhuachalla, É., Sim, W., Fallon, M., Cushen, S., Simmons, C., McMillan, D. C., Laird, B. J., and Ryan, A. ( 2019) The relationship between the BMI‐adjusted weight loss grading system and quality of life in patients with incurable cancer, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12499.

ABSTRACT | PDF |

 

     Article first published online:  06 November 2019

ILynette J. Oost, Marco Sandri, Vanina Romanello

The authors reply: Letter on: “Fibroblast growth factor 21 controls mitophagy and muscle mass” by Oost et al.

no abstract

Oost, L. J., Sandri, M., and Romanello, V. ( 2019) The authors reply: Letter on: “Fibroblast growth factor 21 controls mitophagy and muscle mass” by Oost et al, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12500.

PDF |

 

     Article first published online:  30 October 2019

Mauro Monforte, Francesco Laschena, Pierfrancesco Ottaviani, Maria Rosaria Bagnato, Anna Pichiecchio, Giorgio Tasca, Enzo Ricci

Tracking muscle wasting and disease activity in facioscapulohumeral muscular dystrophy by qualitative longitudinal imaging

Background
Facioscapulohumeral muscular dystrophy (FSHD) is one of the most frequent late‐onset muscular dystrophies, characterized by progressive fatty replacement and degeneration involving single muscles in an asynchronous manner. With clinical trials at the horizon in this disease, the knowledge of its natural history is of paramount importance to understand the impact of new therapies. The aim of this study was to assess disease progression in FSHD using qualitative muscle magnetic resonance imaging, with a focus on the evolution of hyperintense lesions identified on short‐tau inversion recovery (STIR+) sequences, hypothesized to be markers of active muscle injury.
Methods
One hundred genetically confirmed consecutive FSHD patients underwent lower limb muscle magnetic resonance imaging at baseline and after 365 ± 60 days in this prospective longitudinal study. T1 weighted (T1w) and STIR sequences were used to assess fatty replacement using a semiquantitative visual score and muscle oedema. The baseline and follow‐up scans of each patient were also evaluated by unblinded direct comparison to detect the changes not captured by the scoring system.
Results
Forty‐nine patients showed progression on T1w sequences after 1 year, and 30 patients showed at least one new STIR+ lesion. Increased fat deposition at follow‐up was observed in 13.9% STIR+ and in only 0.21% STIR‐ muscles at baseline (P < 0.001). Overall, 89.9% of the muscles that showed increased fatty replacement were STIR+ at baseline and 7.8% were STIR+ at 12 months. A higher number of STIR+ muscles at baseline was associated with radiological worsening (odds ratio 1.17, 95% confidence interval 1.06–1.30, P = 0.003).
Conclusions
Our study confirms that STIR+ lesions represent prognostic biomarkers in FSHD and contributes to delineate its radiological natural history, providing useful information for clinical trial design. Given the peculiar muscle‐by‐muscle involvement in FSHD, MRI represents an invaluable tool to explore the modalities and rate of disease progression.

Monforte, M., Laschena, F., Ottaviani, P., Bagnato, M. R., Pichiecchio, A., Tasca, G., and Ricci, E. ( 2019) Tracking muscle wasting and disease activity in facioscapulohumeral muscular dystrophy by qualitative longitudinal imaging, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002

ABSTRACT | PDF |

 

     Article first published online:  25 October 2019

Martina Baraldo, Alessia Geremia, Marco Pirazzini, Leonardo Nogara, Francesca Solagna, Clara Türk, Hendrik Nolte, Vanina Romanello, Aram Megighian, Simona Boncompagni, Marcus Kruger, Marco Sandri, Bert Blaauw

Skeletal muscle mTORC1 regulates neuromuscular junction stability

Background
Skeletal muscle is a plastic tissue that can adapt to different stimuli. It is well established that Mammalian Target of Rapamycin Complex 1 (mTORC1) signalling is a key modulator in mediating increases in skeletal muscle mass and function. However, the role of mTORC1 signalling in adult skeletal muscle homeostasis is still not well defined.
Methods
Inducible, muscle‐specific Raptor and mTOR k.o. mice were generated. Muscles at 1 and 7 months after deletion were analysed to assess muscle histology and muscle force.
Results
We found no change in muscle size or contractile properties 1 month after deletion. Prolonging deletion of Raptor to 7 months, however, leads to a very marked phenotype characterized by weakness, muscle regeneration, mitochondrial dysfunction, and autophagy impairment. Unexpectedly, reduced mTOR signalling in muscle fibres is accompanied by the appearance of markers of fibre denervation, like the increased expression of the neural cell adhesion molecule (NCAM). Both muscle‐specific deletion of mTOR or Raptor, or the use of rapamycin, was sufficient to induce 3–8% of NCAM‐positive fibres (P < 0.01), muscle fibrillation, and neuromuscular junction (NMJ) fragmentation in 24% of examined fibres (P < 0.001). Mechanistically, reactivation of autophagy with the small peptide Tat‐beclin1 is sufficient to prevent mitochondrial dysfunction and the appearance of NCAM‐positive fibres in Raptor k.o. muscles.
Conclusions
Our study shows that mTOR signalling in skeletal muscle fibres is critical for maintaining proper fibre innervation, preserving the NMJ structure in both the muscle fibre and the motor neuron. In addition, considering the beneficial effects of exercise in most pathologies affecting the NMJ, our findings suggest that part of these beneficial effects of exercise are through the well‐established activation of mTORC1 in skeletal muscle during and after exercise.

Baraldo, M., Geremia, A., Pirazzini, M., Nogara, L., Solagna, F., Türk, C., Nolte, H., Romanello, V., Megighian, A., Boncompagni, S., Kruger, M., Sandri, M., and Blaauw, B. ( 2019) Skeletal muscle mTORC1 regulates neuromuscular junction stability, Journal of Cachexia, Sarcopenia and Muscle, XXX, https://doi.org/10.1002

ABSTRACT | PDF |

 

     Article first published online:  24 October 2019

Maria Carmela Filomena, Daniel L. Yamamoto, Marco Caremani, Vinay K. Kadarla, Giuseppina Mastrototaro, Simone Serio, Anupama Vydyanath, Margherita Mutarelli, Arcamaria Garofalo, Irene Pertici, Ralph Knöll, Vincenzo Nigro, Pradeep K. Luther, Richard L. Lieber, Moriah R. Beck, Marco Linari, Marie‐Louise Bang

Myopalladin promotes muscle growth through modulation of the serum response factor pathway

Background
Myopalladin (MYPN) is a striated muscle‐specific, immunoglobulin‐containing protein located in the Z‐line and I‐band of the sarcomere as well as the nucleus. Heterozygous MYPN gene mutations are associated with hypertrophic, dilated, and restrictive cardiomyopathy, and homozygous loss‐of‐function truncating mutations have recently been identified in patients with cap myopathy, nemaline myopathy, and congenital myopathy with hanging big toe.
Methods
Constitutive MYPN knockout (MKO) mice were generated, and the role of MYPN in skeletal muscle was studied through molecular, cellular, biochemical, structural, biomechanical, and physiological studies in vivo and in vitro.
Results
MKO mice were 13% smaller compared with wild‐type controls and exhibited a 48% reduction in myofibre cross‐sectional area (CSA) and significantly increased fibre number. Similarly, reduced myotube width was observed in MKO primary myoblast cultures. Biomechanical studies showed reduced isometric force and power output in MKO mice as a result of the reduced CSA, whereas the force developed by each myosin molecular motor was unaffected. While the performance by treadmill running was similar in MKO and wild‐type mice, MKO mice showed progressively decreased exercise capability, Z‐line damage, and signs of muscle regeneration following consecutive days of downhill running. Additionally, MKO muscle exhibited progressive Z‐line widening starting from 8 months of age. RNA‐sequencing analysis revealed down‐regulation of serum response factor (SRF)‐target genes in muscles from postnatal MKO mice, important for muscle growth and differentiation. The SRF pathway is regulated by actin dynamics as binding of globular actin to the SRF‐cofactor myocardin‐related transcription factor A (MRTF‐A) prevents its translocation to the nucleus where it binds and activates SRF. MYPN was found to bind and bundle filamentous actin as well as interact with MRTF‐A. In particular, while MYPN reduced actin polymerization, it strongly inhibited actin depolymerization and consequently increased MRTF‐A‐mediated activation of SRF signalling in myogenic cells. Reduced myotube width in MKO primary myoblast cultures was rescued by transduction with constitutive active SRF, demonstrating that MYPN promotes skeletal muscle growth through activation of the SRF pathway.
Conclusions
Myopalladin plays a critical role in the control of skeletal muscle growth through its effect on actin dynamics and consequently the SRF pathway. In addition, MYPN is important for the maintenance of Z‐line integrity during exercise and aging. These results suggest that muscle weakness in patients with biallelic MYPN mutations may be associated with reduced myofibre CSA and SRF signalling and that the disease phenotype may be aggravated by exercise.

Filomena, M. C., Yamamoto, D. L., Caremani, M., Kadarla, V. K., Mastrototaro, G., Serio, S., Vydyanath, A., Mutarelli, M., Garofalo, A., Pertici, I., Knöll, R., Nigro, V., Luther, P. K., Lieber, R. L., Beck, M. R., Linari, M., and Bang, M.‐L. ( 2019) Myopalladin promotes muscle growth through modulation of the serum response factor pathway, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12486.

ABSTRACT | PDF |

 

     Article first published online:  17 October 2019

Kate A. Duchowny, Katherine E. Peters, Steven R. Cummings, Eric S. Orwoll, Andrew R. Hoffman, Kristine E. Ensrud, Jane A. Cauley, William J. Evans, Peggy M. Cawthon for the Osteoporotic Fractures in Men (MrOS) Study Research Group

Association of change in muscle mass assessed by D3‐creatine dilution with changes in grip strength and walking speed

Background
Muscle mass declines with age. However, common assessments used to quantify muscle mass are indirect. The D3‐creatine (D3Cr) dilution method is a direct assessment of muscle mass; however, longitudinal changes have not been examined in relation to changes in other measures of muscle mass, strength, and performance.
Methods
A convenience sample of 40 men from the Osteoporotic Fractures in Men Study (mean age = 83.3 years, standard deviation = 3.9) underwent repeat assessment of D3Cr muscle mass, dual‐energy X‐ray absorptiometry (DXA) lean mass, grip strength, and walking speed at two time points approximately 1.6 years apart (2014–2016). One‐sample t‐tests and Pearson correlations were used to examine changes in DXA total body lean mass, DXA appendicular lean mass/height2, DXA appendicular lean mass/weight, D3Cr muscle mass, D3Cr muscle mass/weight, grip strength, walking speed, and weight.
Results
D3‐creatine muscle mass, D3Cr muscle mass/weight, grip strength, and walking speed all significantly declined (all P < 0.01). The change in DXA measures of lean mass was moderately correlated with changes in D3Cr muscle mass. There was no significant correlation between the change in DXA measures of lean mass and change in walking speed (all P > 0.05). The change in D3Cr muscle mass/weight was moderately correlated with change in walking speed (r = 0.33, P < .05). The change in grip strength was weakly correlated with the change in DXA measures of lean mass and D3Cr muscle mass (r = 0.19–0.32).
Conclusions
The results of our study provide new insights regarding the decline in muscle strength and D3Cr muscle mass. The D3Cr method may be a feasible tool to measure declines in muscle mass over time.

Duchowny, K. A., Peters, K. E., Cummings, S. R., Orwoll, E. S., Hoffman, A. R., Ensrud, K. E., Cauley, J. A., Evans, W. J., Cawthon, P. M., and for the Osteoporotic Fractures in Men (MrOS) Study Research Group ( 2019) Association of change in muscle mass assessed by D3‐creatine dilution with changes in grip strength and walking speed, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12494.

ABSTRACT | PDF |

 

     Article first published online:  30 September 2019

Nima Gharahdaghi, Supreeth Rudrappa, Matthew S. Brook, Iskandar Idris, Hannah Crossland, Claire Hamrock, Muhammad Hariz Abdul Aziz, Fawzi Kadi, Janelle Tarum, Paul L. Greenhaff, Dumitru Constantin‐Teodosiu, Jessica Cegielski, Bethan E. Phillips, Daniel J. Wilkinson, Nathaniel J. Szewczyk, Kenneth Smith, Philip J. Atherton

Testosterone therapy induces molecular programming augmenting physiological adaptations to resistance exercise in older men

Background
The andropause is associated with declines in serum testosterone (T), loss of muscle mass (sarcopenia), and frailty. Two major interventions purported to offset sarcopenia are anabolic steroid therapies and resistance exercise training (RET). Nonetheless, the efficacy and physiological and molecular impacts of T therapy adjuvant to short‐term RET remain poorly defined.
Methods
Eighteen non‐hypogonadal healthy older men, 65–75 years, were assigned in a random double‐blinded fashion to receive, biweekly, either placebo (P, saline, n = 9) or T (Sustanon 250 mg, n = 9) injections over 6 week whole‐body RET (three sets of 8–10 repetitions at 80% one‐repetition maximum). Subjects underwent dual‐energy X‐ray absorptiometry, ultrasound of vastus lateralis (VL) muscle architecture, and knee extensor isometric muscle force tests; VL muscle biopsies were taken to quantify myogenic/anabolic gene expression, anabolic signalling, muscle protein synthesis (D2O), and breakdown (extrapolated).
Results
Testosterone adjuvant to RET augmented total fat‐free mass (P=0.007), legs fat‐free mass (P=0.02), and appendicular fat‐free mass (P=0.001) gains while decreasing total fat mass (P=0.02). Augmentations in VL muscle thickness, fascicle length, and quadriceps cross‐section area with RET occured to a greater extent in T (P < 0.05). Sum strength (P=0.0009) and maximal voluntary contract (e.g. knee extension at 70°) (P=0.002) increased significantly more in the T group. Mechanistically, both muscle protein synthesis rates (T: 2.13 ± 0.21%·day−1 vs. P: 1.34 ± 0.13%·day−1, P=0.0009) and absolute breakdown rates (T: 140.2 ± 15.8 g·day−1 vs. P: 90.2 ± 11.7 g·day−1, P=0.02) were elevated with T therapy, which led to higher net turnover and protein accretion in the T group (T: 8.3 ± 1.4 g·day−1 vs. P: 1.9 ± 1.2 g·day−1, P=0.004). Increases in ribosomal biogenesis (RNA:DNA ratio); mRNA expression relating to T metabolism (androgen receptor: 1.4‐fold; Srd5a1: 1.6‐fold; AKR1C3: 2.1‐fold; and HSD17β3: two‐fold); insulin‐like growth factor (IGF)‐1 signalling [IGF‐1Ea (3.5‐fold) and IGF‐1Ec (three‐fold)] and myogenic regulatory factors; and the activity of anabolic signalling (e.g. mTOR, AKT, and RPS6; P < 0.05) were all up‐regulated with T therapy. Only T up‐regulated mitochondrial citrate synthase activity (P=0.03) and transcription factor A (1.41 ± 0.2‐fold, P=0.0002), in addition to peroxisome proliferator‐activated receptor‐γ co‐activator 1‐α mRNA (1.19 ± 0.21‐fold, P=0.037).
Conclusions
Administration of T adjuvant to RET enhanced skeletal muscle mass and performance, while up‐regulating myogenic gene programming, myocellular translational efficiency and capacity, collectively resulting in higher protein turnover, and net protein accretion. T coupled with RET is an effective short‐term intervention to improve muscle mass/function in older non‐hypogonadal men.

Gharahdaghi, N., Rudrappa, S., Brook, M. S., Idris, I., Crossland, H., Hamrock, C., Abdul Aziz, M. H., Kadi, F., Tarum, J., Greenhaff, P. L., Constantin‐Teodosiu, D., Cegielski, J., Phillips, B. E., Wilkinson, D. J., Szewczyk, N. J., Smith, K., and Atherton, P. J. ( 2019) Testosterone therapy induces molecular programming augmenting physiological adaptations to resistance exercise in older men, Journal of Cachexia, Sarcopenia and Muscle, XXX, doi: https://doi.org/10.1002/jcsm.12472.

ABSTRACT | PDF |