title: Increased nicotinamide adenine dinucleotide phosphate oxidase 4 expression mediates intrinsic airway smooth muscle hypercontractility in asthma.
abstract: BACKGROUND
  Asthma is characterized by disordered airway physiology as a consequence of increased airway smooth muscle contractility. The underlying cause of this hypercontractility is poorly understood.
  
  
  OBJECTIVE
  We sought to investigate whether the burden of oxidative stress in airway smooth muscle in asthma is heightened and mediated by an intrinsic abnormality promoting hypercontractility.
  
  
  METHODS
  We examined the oxidative stress burden of airway smooth muscle in bronchial biopsies and primary cells from subjects with asthma and healthy controls. We determined the expression of targets implicated in the control of oxidative stress in airway smooth muscle and their role in contractility.
  
  
  RESULTS
  We found that the oxidative stress burden in the airway smooth muscle in individuals with asthma is heightened and related to the degree of airflow obstruction and airway hyperresponsiveness. This was independent of the asthmatic environment as in vitro primary airway smooth muscle from individuals with asthma compared with healthy controls demonstrated increased oxidative stress-induced DNA damage together with an increased production of reactive oxygen species. Genome-wide microarray of primary airway smooth muscle identified increased messenger RNA expression in asthma of NADPH oxidase (NOX) subtype 4. This NOX4 overexpression in asthma was supported by quantitative polymerase chain reaction, confirmed at the protein level. Airway smooth muscle from individuals with asthma exhibited increased agonist-induced contraction. This was abrogated by NOX4 small interfering RNA knockdown and the pharmacological inhibitors diphenyleneiodonium and apocynin.
  
  
  CONCLUSIONS
  Our findings support a critical role for NOX4 overexpression in asthma in the promotion of oxidative stress and consequent airway smooth muscle hypercontractility. This implicates NOX4 as a potential novel target for asthma therapy.
authors: Institute for Lung Health, Department of Infection, Immunity and Inflammation, University of Leicester, United Kingdom.
authors: Amanda
authors: A
authors: Sutcliffe
authors: Fay
authors: F
authors: Hollins
authors: Edith
authors: E
authors: Gomez
authors: Ruth
authors: R
authors: Saunders
authors: Camille
authors: C
authors: Doe
authors: Marcus
authors: M
authors: Cooke
authors: R A John
authors: RA
authors: Challiss
authors: Chris E
authors: CE
authors: Brightling
mesh_terms: D000328:Adult; D001249:Asthma / Q000201:enzymology*; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D001980:Bronchi / Q000201:enzymology / Q000503:physiopathology*; D016022:Case-Control Studies; D004249:DNA Damage; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000201:enzymology / Q000503:physiopathology*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism; D000099156:Superoxide Dismutase 2
chemical_list: D015415:Biomarkers; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2; C498910:NOX4 protein, human