The Role of Extracellular Matrix Proteins on Exercise Training-Induced Muscle Fibre Adaptations in COPD

Introduction: Exercise training (EX) induces greater peripheral muscle fibre adaptations in non-cachectic compared to cachectic COPD patients. Extracellular matrix proteins (ECMs) are important regulators of skeletal muscle plasticity. We investigated whether differential expression of ECMs may explain differences in the phenotypic response to EX between cachectic and non-cachectic COPD and healthy individuals.
Methods: The mRNA expression of ECMs in vastus lateralis muscle from cachectic (FFMI; 15.6 Kg.cm2 n=18) and non-cachectic (FFMI: 19.0 Kg.cm2; n=23) COPD was compared to age-matched healthy controls (FFMI: 19.4 Kg.cm2; n = 18), after a 10-week interval EX program. Gene expression was calculated as a fold change using the 2-ΔΔCt method, after normalisation to GAPDH.
Results: EX induced greater osteopontin (Spp1) and tenascin C (Tnc) expression in cachectic compared to non-cachectic COPD patients and healthy (Table 1). In cachectic COPD, EX was linked to lower collagen type-1 (Col1a2) and fibronectin (Fn1) expression compared to healthy individuals (Table 1).

Conclusion: Structural ECMs associated with muscle regeneration were upregulated in cachectic COPD compared to non-cachectic, whereas anti-adhesive ones were downregulated. Differences in muscle fibre ECMs expression in response to exercise stimulus may explain differences in phenotypic adaptations in cachectic compared to non-cachectic COPD.