The effects of bolus supplementation of branched-chain amino acids on skeletal muscle mass, strength, and function in patients with rheumatic disorders during glucocorticoid treatment

The long winding road to the safer glucocorticoid receptor (GR) targeting therapies

Glucocorticoids (Gcs) are widely used to treat inflammatory diseases and hematological malignancies, and despite the introduction of novel anti-inflammatory and anti-cancer biologics, the use of inexpensive and effective Gcs is expected to grow. Unfortunately, chronic treatment with Gcs results in multiple atrophic and metabolic side effects. Thus, the search for safer glucocorticoid receptor (GR)-targeted therapies that preserve therapeutic potential of Gcs but result in fewer adverse effects remains highly relevant. Development of selective GR agonists/modulators (SEGRAM) with reduced side effects, based on the concept of dissociation of GR transactivation and transrepression functions, resulted in limited success, and currently focus has shifted towards partial GR agonists. Additional approach is the identification and inhibition of genes associated with Gcs specific side effects. Others and we recently identified GR target genes REDD1 and FKBP51 as key mediators of Gcs-induced atrophy, and selected and validated candidate molecules for REDD1 blockage including PI3K/Akt/mTOR inhibitors. In this review, we summarized classic and contemporary approaches to safer GR-mediated therapies including unique concept of Gcs combination with REDD1 inhibitors. We discussed protective effects of REDD1 inhibitors against Gcs–induced atrophy in skin and bone and underlined the translational potential of this combination for further development of safer and effective Gcs-based therapies.

Branched chain amino acids in the treatment of polymyositis and dermatomyositis: a phase II/III, multi-center, randomized controlled trial

OBJECTIVES

To assess the efficacy and safety of branched chain amino acids (BCAAs) in the treatment of PM/DM prior to official approval of their use in Japan.

METHODS

Treatment naïve adults with PM/DM were enrolled in a randomized, double-blind trial to receive either TK-98 (drug name of BCAAs) or placebo in addition to conventional treatment. After 12 weeks, patients with an average manual muscle test (MMT) score <9.5 were enrolled in an open label extension study for a further 12 weeks. The primary end point was the change of the MMT score at 12 weeks. The secondary end points were the clinical response and the change of functional index (FI).

RESULTS

Forty-seven patients were randomized either to the TK-98 (n = 24) or placebo (n = 23) groups. The changes of MMT scores at 12 weeks were 0.70±0.19 (mean±SEM) and 0.69±0.18, respectively (P = 0.98). Thirteen patients from the TK-98 group and 12 from the placebo group were enrolled in the extension study. The MMT scores in both groups improved similarly. The increase of the FI scores of the shoulder flexion at 12 weeks was significantly greater in the TK-98 group (27.9±5.67 vs. 12.8±5.67 for the right shoulder flexion, and 27.0±5.44 vs. 13.4±5.95 for the left shoulder [P < 0.05]). Frequencies of adverse events upto 12 weeks were similar.

CONCLUSION

BCAAs showed no effect on the improvement of the muscle strength evaluated by MMT and the clinical response. However, they were partly effective for improving dynamic repetitive muscle functions.

TRIAL REGISTRATION

UMIN-CTR Clinical Trial, https://center6.umin.ac.jp/, UMIN000016233.

Glycine increases fat-free mass in malnourished haemodialysis patients: a randomized double-blind crossover trial

BACKGROUND

Protein energy wasting is associated with negative outcome in patients under chronic haemodialysis (HD). Branched-chain amino acids (BCAAs) may increase the muscle mass. This post hoc analysis of a controlled double-blind randomized crossover study assessed the impact of BCAAs on nutritional status, physical function, and quality of life.

METHODS

We included 36 chronic HD patient features of protein energy wasting as plasma albumin <38 g/L, and dietary intakes <30 kcal/kg/day and <1 g protein/kg/day. Patients received either oral BCAA (2 × 7 g/day) or glycine (2 × 7 g/day) for 4 months (Period 1), followed by a washout period of 1 month, and then received the opposite supplement (Period 2). The outcomes were lean body mass measured by dual-energy X-ray absorptiometry, fat-free mass index measured by bioelectrical impedance, resting energy expenditure, dietary intake and appetite rating, physical activity and function, quality of life, and blood parameters. Analyses were performed by multiple mixed linear regressions including type of supplementation, months, period, sex, and age as fixed effects and subjects as random intercepts.

RESULTS

Twenty-seven patients (61.2 ± 13.7 years, 41% women) were compliant to the supplementations (consumption >80% of packs) and completed the study. BCAA did not affect lean body mass index and body weight, but significantly decreased fat-free mass index, as compared with glycine (coeff -0.27, 95% confidence interval -0.43 to -0.10, P = 0.002, respectively). BCAA and glycine intake had no effect on the other clinical parameters, blood chemistry tests, or plasma amino acids.

CONCLUSIONS

Branched-chain amino acid did not improve lean body mass as compared with glycine. Unexpectedly, glycine improved fat-free mass index in HD patients, as compared with BCAA. Whether long-term supplementation with glycine improves the clinical outcome remains to be demonstrated.

Amino Acid Profile in 18 Patients with Rheumatic Diseases Treated with Glucocorticoids and BCAAs

The administration of glucocorticoids to patients with rheumatic diseases often results in glucocorticoid-induced myopathy. We previously found that administration of branched-chain amino acids (BCAA) to such patients improves the loss of skeletal muscle, however, their individual differences were often observed. The present study, therefore, aims to identify specific parameters associated with BCAA-induced increases in skeletal muscle mass. Eighteen patients with rheumatic diseases treated with prednisolone were randomly assigned to receive additional BCAAs for 12 wk. Serum biochemistry, plasma fibroblast growth factor (FGF) 19 and 21, and plasma and urinary amino acid concentrations were assessed. The relationship between these parameters and the cross-sectional area (CSA) of the biceps femoris (slow-twitch muscle) and rectus femoris (fast-twitch muscle) was assessed using computed tomography. BCAA supplementation increased serum levels of creatinine and albumin and decreased ammonia and urinary 3-methylhistidine levels. With or without BCAA supplementation, each plasma amino acid concentration decreased during the study period, but the decrease was lower in patients receiving BCAA. Interestingly, a positive correlation was observed between plasma isoleucine, aspartate, and glutamate concentrations and improvement in the biceps femoris muscle atrophy. Plasma amino acid concentrations in patients with rheumatic diseases treated with glucocorticoids decreased despite tapering the dose of glucocorticoids, with a smaller decrease in the BCAA-treated group. Plasma BCAA, aspartic acid, and glutamate concentrations correlated positively with the rate of improvement in biceps femoris muscle atrophy, suggesting that these amino acids are associated with the BCAA-induced increase in muscle mass.

Effects of exercise in patients with connective tissue disease receiving high-dose glucocorticoids: A pilot prospective cohort study

PURPOSE

High doses of glucocorticoids induce skeletal muscle weakness. The aim of this study was to evaluate the effects of exercise therapy on skeletal muscle strength, mass, and exercise capacity in patients with connective tissue disease treated with high doses of glucocorticoids.

METHODS

This prospective, observational, single-center, cohort study included 35 patients aged ≥ 15 years diagnosed with connective tissue disease who received high-dose glucocorticoids and physical training. Exercise therapy, including moderate aerobic and strength training, was performed five times a week. Knee extension strength, skeletal muscle mass, anaerobic threshold, and peak oxygen consumption were measured at the beginning of exercise therapy and at discharge.

RESULTS

After 6 weeks of aerobic and strength exercises, skeletal muscle mass significantly decreased by 5.5%, right knee extension decreased by 11.6%, and left knee extension decreased by 9.7%. The anaerobic threshold and peak oxygen consumption significantly increased by 13.0% and 9.0%, respectively. The increase in glucocorticoid dose was inversely correlated with changes in knee extension strength.

CONCLUSION

In patients with connective tissue disease being treated with high-dose glucocorticoids, exercise therapy might attenuate the decrease in skeletal muscle mass and strength and increase the anaerobic threshold and peak oxygen consumption, thus moderating the side effects of high-dose glucocorticoid treatment. Trial registration The trial is registered with UMIN (University Hospital Medical Information Network), ID number UMIN000038836.

Eicosapentaenoic acid changes muscle transcriptome and intervenes in aging-related fiber type transition in male mice

Age-related sarcopenia is associated with a variety of changes in skeletal muscle. These changes are interrelated with each other and associated with systemic metabolism, the details of which, however, are largely unknown. Eicosapentaenoic acid (EPA) is a promising nutrient against sarcopenia and has multifaceted effects on systemic metabolism. In this study, we hypothesized that the aging process in skeletal muscle can be intervened by the administration of EPA. Seventy-five-week-old male mice were assigned to groups fed an EPA-deprived diet (EPA-) or an EPA-enriched diet with 1 wt% EPA (EPA+) for 12 wk. Twenty-four-week-old male mice fed with normal chow were also analyzed. At baseline, the grip strength of the aging mice was lower than that of the young mice. After 12 wk, EPA+ showed similar muscle mass but increased grip strength compared with EPA-. EPA+ displayed higher insulin sensitivity than EPA-. Immunohistochemistry and gene expression analysis of myosin heavy chains (MyHCs) revealed fast-to-slow fiber type transition in aging muscle, which was partially inhibited by EPA. RNA sequencing (RNA-Seq) analysis suggested that EPA supplementation exerts pathway-specific effects in skeletal muscle including the signatures of slow-to-fast fiber type transition. In conclusion, we revealed that aging skeletal muscle in male mice shows lower grip strength and fiber type changes, both of which can be inhibited by EPA supplementation irrespective of muscle mass alteration.NEW & NOTEWORTHY This study demonstrated that the early phenotype of skeletal muscle in aging male mice is characterized by muscle weakness with fast-to-slow fiber type transition, which could be ameliorated by feeding with EPA-enriched diet. EPA induced metabolic changes such as an increase in systemic insulin sensitivity and altered muscle transcriptome in the aging mice. These changes may be related to the fiber type transition and influence muscle quality.