title: Collagen Type III and VI Turnover in Response to Long-Term Immobilization.
abstract: BACKGROUND
  Muscle mass and function are perturbed by immobilization and remobilization. When muscle mass changes, the quality and quantity of the extracellular matrix protein, particularly the collagens, change with it. In this study, we investigated the temporal profile of three peptide biomarkers derived from turnover of collagen type III and type VI in a long-term immobilization and remobilization study. We also compared individual biomarker levels with Lean body Mass (LBM) and changes therein, hypothesizing that these biomarkers would be biomarkers of the remodeling processes associated with immobilization and/or remobilization.
  
  
  METHODS
  In the Berlin bed rest study, 20 young men were recruited and randomly assigned to 8-week's strict bed rest with or without resistive vibration exercise countermeasure. We measured three neo-epitope ELISA kits in the serum samples of this study: Pro-C3, measured the synthesis of collagen type III; Pro-C6, measured the synthesis of collagen type VI; and C6M measured the degradation of collagen type VI induced by MMP-2 and MMP-9 cleavage.
  
  
  RESULTS
  Pro-C3 and Pro-C6 biomarkers are up-regulated with both immobilization and remobilization, whereas C6M is hardly affected at all. We found that Pro-C3 and C6M levels are related to LBM at baseline and that high levels of Pro-C6 are associated with smaller changes in muscle mass during both immobilization and remobilization.
  
  
  CONCLUSIONS
  The Pro-C3 and-C6 biomarkers change likely reflect remodeling changes in response to unloading or reloading, whereas C6M does not appear to respond to unloading. Pro-C3 and C6M levels correlate with LBM at baseline, while Pro-C6 is related to the anabolic and catabolic responses to unloading and reloading.
authors.affiliation: Nordic Bioscience Biomarkers and Research, Herlev, Denmark.
authors.forename: Shu
authors.initials: S
authors.lastname: Sun
authors.affiliation: Nordic Bioscience Biomarkers and Research, Herlev, Denmark.
authors.forename: Kim
authors.initials: K
authors.lastname: Henriksen
authors.affiliation: Nordic Bioscience Biomarkers and Research, Herlev, Denmark.
authors.forename: Morten A
authors.initials: MA
authors.lastname: Karsdal
authors.affiliation: Nordic Bioscience Biomarkers and Research, Herlev, Denmark.
authors.forename: Inger
authors.initials: I
authors.lastname: Byrjalsen
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Köln, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Rittweger
authors.affiliation: Center for Muscle and Bone Research, Charité Universitätsmedizin Berlin and Free and Humboldt Universities, Berlin, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Armbrecht
authors.affiliation: Center for Muscle and Bone Research, Charité Universitätsmedizin Berlin and Free and Humboldt Universities, Berlin, Germany.|Deakin University, Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Burwood, Victoria, 3125, Australia.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Belavy
authors.affiliation: Center for Muscle and Bone Research, Charité Universitätsmedizin Berlin and Free and Humboldt Universities, Berlin, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Felsenberg
authors.affiliation: Nordic Bioscience Biomarkers and Research, Herlev, Denmark.|Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Copenhagen NW, Denmark.
authors.forename: Anders F
authors.initials: AF
authors.lastname: Nedergaard
mesh_terms: D000328:Adult; D001510:Bed Rest; D015415:Biomarkers / Q000097:blood*; D016022:Case-Control Studies; D024061:Collagen Type III / Q000097:blood*; D024142:Collagen Type VI / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005081:Exercise Therapy; D005500:Follow-Up Studies; D006801:Humans; D007103:Immobilization / Q000379:methods*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D011379:Prognosis; D055815:Young Adult
chemical_list: D015415:Biomarkers; D024061:Collagen Type III; D024142:Collagen Type VI