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Nitric Oxide Synthase Isoenzyme Expression and Activity in Peripheral Lung Tissue of Patients with Chronic Obstructive Pulmonary Disease

¹ Section of Airway Disease, National Heart and Lung Institute, Imperial College, London, United Kingdom; and ² University of British Columbia and the James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research, St. Paul's Hospital, Vancouver, British Columbia, Canada

Correspondence and requests for reprints should be addressed to Kazuhiro Ito, Ph.D., Section of Airway Disease, National Heart and Lung Institute, Imperial College London, Dovehouse Street, London SW3 6LY, UK. E-mail: k.ito{at}imperial.ac.uk

Rationale: Nitric oxide (NO) is increased in the lung periphery of patients with chronic obstructive pulmonary disease (COPD). However, expression of the NO synthase(s) responsible for elevated NO has not been identified in the peripheral lung tissue of patients with COPD of varying severity.

Objectives:

Methods: Protein and mRNA expression of nitric oxide synthase type I (neuronal NOS [nNOS]), type II (inducible NOS [iNOS]), and type III (endothelial NOS [eNOS]) were quantified by Western blotting and reverse transcription-polymerase chain reaction, respectively, in specimens of surgically resected lung tissue from nonsmoker control subjects, patients with COPD of varying severity, and smokers without COPD, and in a lung epithelial cell line (A549). The effects of nitrative/oxidative stress on NOS expression and activity were also evaluated in vitro in A549 cells. nNOS nitration was quantified by immunoprecipitation and dimerization of nNOS was detected by low-temperature SDS–PAGE/Western blot in the presence of the peroxynitrite generator, 3-morpholinosydnonimine-N-ethylcarbamide (SIN1), in vitro and in vivo.

Measurements and Main Results: Lung tissue from patients with severe and very severe COPD had graded increases in nNOS (mRNA and protein) compared with nonsmokers and normal smokers. Hydrogen peroxide (H₂O₂) and SIN1 as well as the cytokine mixture (IFN-, IL-1β, and tumor necrosis factor-) increased mRNA expression and activity of nNOS in A549 cells in a concentration-dependent manner compared with nontreated cells. Tyrosine nitration resulted in an increase in nNOS activity in vitro, but did not affect its dimerization.

Conclusions: Patients with COPD have a significant increase in nNOS expression and activity that reflects the severity of the disease and may be secondary to oxidative stress.

Key Words: nitric oxide synthase • nitrosative stress • nitration • chronic obstructive pulmonary disease

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject Nitric oxide is increased in the peripheral lungs of patients with chronic obstructive pulmonary disease (COPD); however, the source is unclear. What This Study Adds to the Field Neuronal nitric oxide synthase expression and activity are increased in patients with COPD according to the severity of their disease, and this may be the cause of high levels of nitrative stress in peripheral lung.

 

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Nitric Oxide Synthase Isoforms in Lung Parenchyma of Patients with Chronic Obstructive Pulmonary Disease

Massimo Corradi and Antonio Mutti
AJRCCM 2010 181: 3-4. [Full Text]  

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				M. Corradi and A. Mutti Nitric Oxide Synthase Isoforms in Lung Parenchyma of Patients with Chronic Obstructive Pulmonary Disease Am. J. Respir. Crit. Care Med., January 1, 2010; 181(1): 3 - 4. [Full Text] [PDF]