Effect of a pulmonary rehabilitation (PR) programme on extracellular matrix (ECM) protein expression in vastus lateralis muscle in atrophic and non-atrophic COPD

<bold>Background:</bold> The type of muscle fibre remodelling, in terms of hypertrophy and phenotypic adaptations, differs between COPD with peripheral muscle wasting (atrophic COPD) and those without wasting (non-atrophic COPD) in response to exercise-based PR (Vogiatzis et al ERJ 2010). Here, we investigated whether attenuated exercise-induced myogenesis in atrophic COPD is partially explained by changes in the expression of ECM proteins. <bold>Methods:</bold> Vastus lateralis ECM biomarker expression from atrophic (<17 Kg.m², n=10) and non-atrophic COPD (>17.3 Kg.m², n=19) was quantified using ELISA before and after a 10-week PR. <bold>Results:</bold> Mean muscle fibre cross-sectional area increased in both groups, but significantly less in atrophic (7±2%) than in non-atrophic (11±2%) COPD. In non-atrophic COPD, PR-induced myogenic adaptations were accompanied by increased levels in the ECM biomarkers measured. In atrophic COPD, PR induced limited myogenic adaptations without any changes in ECM biomarkers, apart from the dystrophic biomarker osteopontin, which was increased following PR (<bold>Figure 1</bold>). <bold>Conclusion:</bold> In response to PR the expression of intramuscular ECM biomarkers remained unchanged in atrophic compared to non-atrophic COPD. This finding suggests that the limited PR-induced muscle fibre hypertrophy in atrophic COPD could be associated with impaired intramuscular ECM expression. <fig><object-id>erj;64/suppl_68/OA3675/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>