title: Reduced denitration activity in peripheral lung of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Accumulation of nitrated protein is seen in peripheral lung and cells from patients with chronic obstructive pulmonary disease (COPD). Nitrated protein causes abnormal protein function, but the nitration was believed to be an irreversible process. However, there are accumulating evidences that this process is reversible by an active denitration pathway. The aim of this study is to detect denitration activity in protein extracts from peripheral lung tissue of COPD and to compare with those in healthy subjects.
  
  
  METHODS
  Peripheral lung tissue from 4 healthy, 4 smokers without COPD, 4 GOLD stage 1 and 4 GOLD stage 2 were used for denitration assay. Denitration activity was determined as reduction of nitro-tyrosine level of nitrated histone protein after incubation with protein extracts from peripheral lung, which was determined by western blotting. In addition, RNA is extracted from peripheral lung of 8 healthy, 7 smoking control, 8 stage 1 and 2 COPD and 10 stage 3 and 4 COPD and nitrate reductase mRNA expression was determined by real time RT-PCR.
  
  
  RESULTS
  Peripheral lung protein extracts from healthy subjects reduced nitro-tyrosine level of nitrated histone. Thus, we were able to show denitration activity in peripheral lungs. The denitration activity was slightly reduced in smoking controls, and significantly reduced in COPD patients. We also showed that the expression of the human homologue of nitrate reductase (chytochrome β2 reductase), a potential candidate of denitrase, was significanty reduced in COPD lung.
  
  
  CONCLUSIONS
  This study suggests that accumulation of nitrated protein in lung tissue of COPD may, at least in part, be induced by a reduction in denitration activity or nitrate reductase.
authors.affiliation: Airway Disease, National Heart and Lung Institute, Imperial College, London, UK.
authors.forename: Grace O
authors.initials: GO
authors.lastname: Osoata
authors.affiliation: Airway Disease, National Heart and Lung Institute, Imperial College, London, UK.
authors.forename: Misako
authors.initials: M
authors.lastname: Ito
authors.affiliation: The University of British Columbia, The James Hogg-iCAPTURE Center for Cardiovascular and Pulmonary Research, St. Paul's Hospital, Vancouver, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Elliot
authors.affiliation: The University of British Columbia, The James Hogg-iCAPTURE Center for Cardiovascular and Pulmonary Research, St. Paul's Hospital, Vancouver, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Hogg
authors.affiliation: Airway Disease, National Heart and Lung Institute, Imperial College, London, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Barnes
authors.affiliation: Airway Disease, National Heart and Lung Institute, Imperial College, London, UK.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ito
keywords: COPD; Denitration; Nitrate reductase; Nitrative stress; Nitrotyrosine