title: Correlation between the bronchial subepithelial layer and whole airway wall thickness in patients with asthma.
abstract: BACKGROUND
  The epithelial reticular basement membrane (Rbm) of the airway wall thickens in patients with asthma. However, whether the thickening parallels whole airway wall thickening, which limits airflow, is unknown. The aim of this study was to examine the correlation between the bronchial Rbm thickening and whole airway wall thickening in asthma. In addition, the association of Rbm and whole wall thickening with airflow obstruction was examined.
  
  
  METHODS
  Forty nine patients with asthma and 18 healthy control subjects took part in the study. The Rbm thickness was measured in bronchial biopsy specimens and whole airway wall thickness was assessed with high resolution computed tomographic (HRCT) scanning after pretreatment with oral steroids for 2 weeks and inhaled beta2 agonist to minimise reversible changes of the airway walls. The percentage airway wall area (WA%; defined as (wall area/total airway area) x 100) and percentage airway wall thickness (WT%; defined as [(ideal outer diameter - ideal luminal diameter)/ideal outer diameter] x 100) were determined from HRCT scans to assess whole airway wall thickness. Spirometric tests were also performed.
  
  
  RESULTS
  WA% and WT% were higher in patients with asthma than in healthy subjects. Both WA% and WT% were strongly correlated with Rbm thickness. Moreover, these three indices of airway wall thickness were inversely correlated with the percentage of predicted forced expiratory volume in 1 second in patients with asthma.
  
  
  CONCLUSIONS
  These findings indicate that Rbm thickening parallels whole airway wall thickening which can cause irreversible airflow obstruction in patients with asthma.
authors.affiliation: First Department of Internal Medicine, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan. kasa3561@med.showa-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Kasahara
authors.forename: K
authors.initials: K
authors.lastname: Shiba
authors.forename: T
authors.initials: T
authors.lastname: Ozawa
authors.forename: K
authors.initials: K
authors.lastname: Okuda
authors.forename: M
authors.initials: M
authors.lastname: Adachi
mesh_terms: D001249:Asthma / Q000473:pathology* / Q000503:physiopathology; D001706:Biopsy / Q000379:methods; D001980:Bronchi / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods