title: Analysis of growth factors and inflammatory cytokines in exhaled breath condensate from asthmatic children.
abstract: BACKGROUND
  Vascular endothelial growth factor (VEGF), AA isoform of platelet-derived growth factor (PDGF-AA), and epidermal growth factor (EGF) are involved in the pathogenesis of airway inflammation in asthma. These molecules are closely associated with cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-4. This study investigates the relation between childhood asthma and levels of these mediators in exhaled breath condensate (EBC).
  
  
  METHODS
  EBC was collected from asthmatic children and controls using a disposable collection kit, and the concentrations of VEGF, PDGF-AA, EGF, TNF-alpha and IL-4 in EBC were measured using sandwich enzyme immunoassays. Exhaled nitric oxide concentration was measured by a chemiluminescence analyzer.
  
  
  RESULTS
  Thirty-five asthmatic patients aged between 7 and 18 years and 11 controls were recruited. Sixteen patients had intermittent asthma (IA) whereas 19 of them suffered from persistent asthma (PA). A significant correlation was found between IL-4 and TNF-alpha in EBC (rho = 0.374, p = 0.010). PDGF-AA levels in EBC were higher in subjects with diminished FEV1 (p = 0.023) whereas IL-4 concentrations were increased in asthmatics (p = 0.007) as well as subjects with increased plasma total IgE (p = 0.033). Patients with PA receiving high-dose inhaled corticosteroid (ICS) had higher EBC IL-4 concentration than those on low-dose ICS (p = 0.007). Linear regression revealed that PDGF-AA levels in EBC were negatively associated with FEV1 percentage (beta = -0.459, p = 0.006) among the asthmatic patients.
  
  
  CONCLUSIONS
  IL-4 in EBC is increased in childhood asthma, and growth factors are detectable in a significant proportion of these children. Increased PDGF-AA is found in asthmatics with more severe airflow limitation.
authors.affiliation: Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong SAR, China. leung2142@cuhk.edu.hk
authors.forename: Ting-Fan
authors.initials: TF
authors.lastname: Leung
authors.forename: Gary W K
authors.initials: GW
authors.lastname: Wong
authors.forename: Fanny W S
authors.initials: FW
authors.lastname: Ko
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Li
authors.forename: Edmund
authors.initials: E
authors.lastname: Yung
authors.forename: Christopher W K
authors.initials: CW
authors.lastname: Lam
authors.forename: Tai-Fai
authors.initials: TF
authors.lastname: Fok
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000276:immunology* / Q000378:metabolism*; D001944:Breath Tests; D002648:Child; D016207:Cytokines / Q000032:analysis / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000032:analysis; D005260:Female; D005541:Forced Expiratory Volume; D006133:Growth Substances / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D015847:Interleukin-4 / Q000032:analysis; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D010982:Platelet-Derived Growth Factor / Q000032:analysis; D018709:Statistics, Nonparametric; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis; D014797:Vital Capacity
chemical_list: D016207:Cytokines; D006133:Growth Substances; D010982:Platelet-Derived Growth Factor; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; C075278:platelet-derived growth factor A; D015847:Interleukin-4; D009569:Nitric Oxide; D007073:Immunoglobulin E; D004815:Epidermal Growth Factor