title: Airway wall geometry in asthma and nonasthmatic eosinophilic bronchitis.
abstract: BACKGROUND
  Variable airflow obstruction and airway hyperresponsiveness (AHR) are features of asthma, which are absent in nonasthmatic eosinophilic bronchitis (EB). Airway remodelling is characteristic of both conditions suggesting that remodelling and airway dysfunction are disassociated, but whether the airway geometry differs between asthma and nonasthmatic EB is uncertain.
  
  
  METHODS
  We assessed airway geometry by computed tomography (CT) imaging in asthma vs EB. A total of 12 subjects with mild-moderate asthma, 14 subjects with refractory asthma, 10 subjects with EB and 11 healthy volunteers were recruited. Subjects had a narrow collimation (0.75 mm) CT scan from the aortic arch to the carina to capture the right upper lobe apical segmental bronchus (RB1). In subjects with asthma and EB, CT scans were performed before and after a 2-week course of oral prednisolone (0.5 mg/kg).
  
  
  RESULTS
  Mild-moderate and refractory asthma were associated with RB1 wall thickening in contrast to subjects with nonasthmatic EB who had maintained RB1 patency without wall thickening [mean (SD) % wall area and luminal area mild-t0-moderate asthma 67.7 (7.3)% and 6.6 (2.8) mm(2)/m(2), refractory asthma 67.3 (5.6)% and 6.7 (3.4) mm(2)/m(2), healthy control group 59.7 (6.3)% and 8.7 (3.8) mm(2)/m(2), EB 61.4 (7.8)% and 11.1 (4.6) mm(2)/m(2) respectively; P < 0.05]. Airway wall thickening of non-RB1 airways generation three to six was a feature of asthma only. There was no change in airway geometry of RB1 after prednisolone. Proximal airway wall thickening was associated with AHR in asthma (r = -0.56; P = 0.02).
  
  
  CONCLUSIONS
  Maintained airway patency in EB may protect against the development of AHR, whereas airway wall thickening may promote AHR in asthma.
authors.affiliation: Institute of Lung Health, Leicester, UK.
authors.forename: S
authors.initials: S
authors.lastname: Siddiqui
authors.forename: S
authors.initials: S
authors.lastname: Gupta
authors.forename: G
authors.initials: G
authors.lastname: Cruse
authors.forename: P
authors.initials: P
authors.lastname: Haldar
authors.forename: J
authors.initials: J
authors.lastname: Entwisle
authors.forename: S
authors.initials: S
authors.lastname: Mcdonald
authors.forename: P J
authors.initials: PJ
authors.lastname: Whithers
authors.forename: S V
authors.initials: SV
authors.lastname: Hainsworth
authors.forename: H O
authors.initials: HO
authors.lastname: Coxson
authors.forename: C
authors.initials: C
authors.lastname: Brightling
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000473:pathology*; D001980:Bronchi / Q000473:pathology*; D016535:Bronchial Hyperreactivity / Q000473:pathology; D001991:Bronchitis / Q000473:pathology*; D004802:Eosinophilia / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed