Supplementation with a selective amino acid formula ameliorates muscular dystrophy in mdx mice

Stefania Banfi,Marzia Belicchi,Chiara Ruocco,Yvan Torrente,Caterina Lonati,Enzo Nisoli,Francesco Bifari,Elisa Donato,Silvia Erratico,Giuseppe D’Antona,Mirella Meregalli,Pamela Bella,Stefano Campaner,Fabio Rossi

doi:10.1038/s41598-018-32613-w

Abstract

Duchenne muscular dystrophy (DMD) is one of the most common and severe forms of muscular dystrophy. Oxidative myofibre content, muscle vasculature architecture and exercise tolerance are impaired in DMD. Several studies have demonstrated that nutrient supplements ameliorate dystrophic features, thereby enhancing muscle performance. Here, we report that dietary supplementation with a specific branched-chain amino acid-enriched mixture (BCAAem) increased the abundance of oxidative muscle fibres associated with increased muscle endurance in dystrophic mdx mice. Amelioration of the fatigue index in BCAAem-treated mdx mice was caused by a cascade of events in the muscle tissue, which were promoted by endothelial nitric oxide synthase (eNOS) activation and vascular endothelial growth factor (VEGF) expression. VEGF induction led to recruitment of bone marrow (BM)-derived endothelial progenitors (EPs), which increased the capillary density of dystrophic skeletal muscle. Functionally, BCAAem mitigated the dystrophic phenotype of mdx mice without inducing dystrophin protein expression or replacing the dystrophin-associated glycoprotein (DAG) complex in the membrane, which is typically lost in DMD. BCAAem supplementation could be an effective adjuvant strategy in DMD treatment.

Highlights

Duchenne muscular dystrophy (DMD) is one of the most common and severe forms of muscular dystrophy
We have demonstrated that endothelial nitric oxide synthase (eNOS) is involved in the effect of dietary supplementation with a selective branched-chain amino acid-enriched mixture (BCAAem) on PGC-1α and sirtuin 1 expression in cardiac and skeletal muscles of middle-aged mice[42]
BCAAem-treated male (n = 5) and female (n = 5) mdx mice were compared to age-matched untreated male (n = 5) and female (n = 5) mdx mice and to BCAAem-treated and untreated wild-type C57BL6/J and eNOS−/− mice (5 males and 5 females in each group) (Figs 1 and S2). eNOS−/− mice were included in this study because we previously reported that BCAAem treatment increased eNOS expression and activation in cardiomyocytes, whereas eNOS KO cells were insensitive to BCAAem[42]

Summary

Introduction

Duchenne muscular dystrophy (DMD) is one of the most common and severe forms of muscular dystrophy. Except for an increase in the CD31+ vessels/section ratio in the VM (not statistically significant) and TA (p < 0.001, one-way ANOVA with Bonferroni correction) muscles of BCAAem-treated compared to the values observed for untreated C57BL6/J mice, no differences were observed in either type of muscle in eNOS−/− mice of either sex with or without amino acid treatment (Fig. 5).

Results

Conclusion