Reduced myotube diameter, atrophic signalling and elevated oxidative stress in cultured satellite cells from COPD patients

Abstract

The mechanisms leading to skeletal limb muscle dysfunction in chronic obstructive pulmonary disease (COPD) have not been fully elucidated. Exhausted muscle regenerative capacity of satellite cells has been evocated, but the capacity of satellite cells to proliferate and differentiate properly remains unknown. Our objectives were to compare the characteristics of satellite cells derived from COPD patients and healthy individuals, in terms of proliferative and differentiation capacities, morphological phenotype and atrophy/hypertrophy signalling, and oxidative stress status. Therefore, we purified and cultivated satellite cells from progressively frozen vastus lateralis biopsies of eight COPD patients and eight healthy individuals. We examined proliferation parameters, differentiation capacities, myotube diameter, expression of atrophy/hypertrophy markers, oxidative stress damages, antioxidant enzyme expression and cell susceptibility to H2O2 in cultured myoblasts and/or myotubes. Proliferation characteristics and commitment to terminal differentiation were similar in COPD patients and healthy individuals, despite impaired fusion capacities of COPD myotubes. Myotube diameter was smaller in COPD patients (P = 0.015), and was associated with a higher expression of myostatin (myoblasts: P = 0.083; myotubes: P = 0.050) and atrogin-1 (myoblasts: P = 0.050), and a decreased phospho-AKT/AKT ratio (myoblasts: P = 0.022). Protein carbonylation (myoblasts: P = 0.028; myotubes: P = 0.002) and lipid peroxidation (myotubes: P = 0.065) were higher in COPD cells, and COPD myoblasts were significantly more susceptible to oxidative stress. Thus, cultured satellite cells from COPD patients display characteristics of morphology, atrophic signalling and oxidative stress similar to those described in in vivo COPD skeletal limb muscles. We have therefore demonstrated that muscle alteration in COPD can be studied by classical in vitro cellular models.

Factors secreted from high glucose treated endothelial cells impair expansion and differentiation of human skeletal muscle satellite cells

“…; Pomiès et al . ). There was no difference in myotube size; however, the reduction in nucleation in HG+DM myotubes resulted in a larger MND.…”

“…These results are consistent with differentiation data from models of T2DM, ageing and CVD (Aragno et al 2004;Nguyen et al 2011;Sousa-Victor & Muñoz-Cánoves, 2016). Myonuclear fusion was less robust after HG+DM treatment, resulting in myotubes with fewer nuclei, a response that is mirrored in human culture and animal models of CVD and T2DM (Aragno et al 2004;Pomiès et al 2015). There was no difference in myotube size; however, the reduction in nucleation in HG+DM myotubes resulted in a larger MND.…”

Hypoxia Impairs Muscle Function and Reduces Myotube Size in Tissue Engineered Skeletal Muscle

“…The role of p70S6 kinase in driving cellular hypertrophy is well defined [Shah et al, ], and it has also recently been shown that this protein kinase is required for increases in muscle force during hypertrophy [Marabita et al, ]. Furthermore, blunted signaling through the Akt‐mTORC1 axis has been shown in hypoxia treated cells [Caron et al, ], rodents [Favier et al, ; de Theije et al, ], and individuals suffering from COPD [Favier et al, ] as well as myotubes in vitro derived from COPD muscle [Pomiès et al, ]. This therefore suggests that the dampening of p70S6 kinase phosphorylation as a consequence of hypoxic exposure may in part instigate the loss of myotube size and muscle force production, and provides more evidence that engineered muscle exposed to hypoxia in vitro responds in a manner akin to that of diseased muscle and is comparable to other cell and animal models.…”

The rat model of COPD skeletal muscle dysfunction induced by progressive cigarette smoke exposure: a pilot study

“…Specifically, we determined the expressions of the Atrogin-1 and MuRF1 E3 ligases responsible for identifying the target proteins destined for degradation [43]. One study available in the literature shows that the expression of Atrogin-1 in muscle cells and tubes of COPD patients is significantly higher than that in healthy individuals [44]. Another study demonstrates that COPD rats showing significantly reduced grip strength and aerobic exercise capacity also exhibit increased levels of E3 ligase proteins in their skeletal muscles [45].…”