title: [Activation of satellite cells in the intercostal muscles of patients with chronic obstructive pulmonary disease].
abstract: OBJECTIVE
  The respiratory muscles of patients with chronic obstructive pulmonary disease (COPD) display evidence of structural damage in parallel with signs of adaptation. We hypothesized that this can only be explained by the simultaneous activation of satellite cells. The aim of this study was to analyze the number and activation of those cells along with the expression of markers of microstructural damage that are frequently associated with regeneration.
  
  
  METHODS
  The study included 8 patients with severe COPD (mean [SD] forced expiratory volume in 1 second, 33% [9%] of predicted) and 7 control subjects in whom biopsies were performed of the external intercostal muscle. The samples were analyzed by light microscopy to assess muscle fiber phenotype, electron microscopy to identify satellite cells, and real-time polymerase chain reaction to analyze the expression of the following markers: insulin-like growth factor 1, mechano growth factor, and embryonic and perinatal myosin heavy chains (MHC) as markers of microstructural damage; Pax-7 and m-cadherin as markers of the presence and activation of satellite cells, respectively; and MHC-I, IIa, and IIx as determinants of muscle fiber phenotype.
  
  
  RESULTS
  The patients had larger fibers than healthy subjects (54 [6] vs 42 [4] microm(2); P< .01) with a similar or slightly increased proportion of satellite cells, as measured by ultrastructural analysis (4.3% [1%] vs 3.7% [3.5%]; P>.05) or expression of Pax-7 (5.5 [4.1] vs 1.6 [0.8] arbitrary units [AU]; P< .05). In addition, there was greater activation of satellite cells in the patients, as indicated by increased expression of m-cadherin (3.8 [2.1] vs 1.0 [1.2] AU; P=.05). This was associated with increased expression of markers of microstructural damage: insulin-like growth factor 1, 0.35 (0.34) vs 0.09 (0.08) AU (P< .05); mechano growth factor, 0.45 (0.55) vs 0.13 (0.17) AU (P=.05).
  
  
  CONCLUSIONS
  The intercostal muscles of patients with severe COPD show indirect signs of microstructural damage accompanied by satellite cell activation. This suggests the presence of ongoing cycles of lesion and repair that could partially explain the maintenance of the structural properties of the muscle.
authors.affiliation: Servei de Pneumologia, Hospital del Mar-IMIM, Barcelona, España.
authors.forename: Juana
authors.initials: J
authors.lastname: Martínez-Llorens
authors.forename: Carme
authors.initials: C
authors.lastname: Casadevall
authors.forename: Josep
authors.initials: J
authors.lastname: Lloreta
authors.forename: Mauricio
authors.initials: M
authors.lastname: Orozco-Levi
authors.forename: Esther
authors.initials: E
authors.lastname: Barreiro
authors.forename: Joan
authors.initials: J
authors.lastname: Broquetas
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gea
mesh_terms: D000368:Aged; D001706:Biopsy; D005260:Female; D006801:Humans; D007366:Intercostal Muscles / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000503:physiopathology*; D032496:Satellite Cells, Skeletal Muscle / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology