title: The Ratio of Free to Bound Desmosine and Isodesmosine May Reflect Emphysematous Changes in COPD.
abstract: BACKGROUND
  The unique elastin crosslinks, desmosine and isodesmosine (DID) are significantly elevated in blood, urine, and sputum from patients with COPD, and may decline following treatment of the disease. However, the large degree of variance in this biomarker among COPD patients with similar levels of disease suggests that it has limited prognostic value with regard to the degree of lung disease in a given individual. As an alternative to measuring the total amount of DID, we propose using the ratio of free to peptide-bound DID, which may provide a better indication of overall lung disease.
  
  
  METHODS
  To test this hypothesis, the free/bound DID ratio was measured in bronchoalveolar lavage fluid (BALF) from both hamsters with elastase-induced emphysema and controls not given the enzyme, using a combination of liquid chromatography and tandem mass spectroscopy. This ratio was then correlated with airspace enlargement, as measured by the mean percentage of lung surface area at ×100 microscopic magnification.
  
  
  RESULTS
  There was a significant negative correlation between the free/bound DID ratio in BALF and lung surface area. However, there was no correlation between this ratio and total BALF DID, suggesting that free/bound DID is unrelated to the immediate rate of breakdown of elastic fibers, and may instead measure the cumulative effect of elastase injury in the lung.
  
  
  CONCLUSIONS
  The free/bound DID ratio may be a useful measure of emphysematous changes in the lung and might also serve as a screening procedure for healthy smokers and other individuals at risk for developing COPD.
authors.affiliation: St John's University, New York, NY, USA.
authors.forename: Xingjian
authors.initials: X
authors.lastname: Liu
authors.forename: Shuren
authors.initials: S
authors.lastname: Ma
authors.forename: Sophie
authors.initials: S
authors.lastname: Liu
authors.forename: Ming
authors.initials: M
authors.lastname: Liu
authors.forename: Gerard
authors.initials: G
authors.lastname: Turino
authors.forename: Jerome
authors.initials: J
authors.lastname: Cantor
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002853:Chromatography, Liquid; D003895:Desmosine / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D007524:Isodesmosine / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D008647:Mesocricetus; D010196:Pancreatic Elastase; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000378:metabolism*; D011656:Pulmonary Emphysema / Q000139:chemically induced / Q000175:diagnosis / Q000378:metabolism*; D012720:Severity of Illness Index; D053719:Tandem Mass Spectrometry
chemical_list: D015415:Biomarkers; D003895:Desmosine; D007524:Isodesmosine; D010196:Pancreatic Elastase