Increased airway smooth muscle in preschool wheezers who have asthma at school age

J Allergy Clin Immunol. 2013 Apr;131(4):1024-32, 1032.e1-16. doi: 10.1016/j.jaci.2012.08.044. Epub 2012 Oct 12.


Background: Increased airway smooth muscle (ASM) is a feature of established asthma in schoolchildren, but nothing is known about ASM in preschool wheezers.

Objective: We sought to determine endobronchial biopsy specimen ASM area fraction in preschool wheezers and its association with asthma at school age.

Methods: ASM area, reticular basement membrane thickness, and mucosal eosinophil and ASM mast cell values were quantified in endobronchial biopsy specimens previously obtained from preschool children undergoing clinically indicated bronchoscopy: severe recurrent wheezers (n=47; median age, 26 months) and nonwheezing control subjects (n=21; median age, 15 months). Children were followed up, and asthma status was established at age 6 to 11 years. Preschool airway pathology was examined in relation to asthma at school age.

Results: Forty-two (62%) of 68 children had 1 or more evaluable biopsy specimens for ASM. At school age, 51 of 68 children were followed up, and 15 (40%) of 37 preschool wheezers had asthma. Children who had asthma and an evaluable biopsy specimen had increased preschool ASM area fraction (n=8; median age, 8.2 years [range, 6-10.4 years]; median ASM, 0.12 [range, 0.08-0.16]) compared with that seen in children without asthma (n=24; median age, 7.3 years [range, 5.9-11 years]; median ASM, 0.07 [range, 0.02-0.23]; P=.007). However, preschool reticular basement membrane thickness and mucosal eosinophil or ASM mast cell values were not different between those who did or did not have asthma at school age.

Conclusion: Increased preschool ASM is associated with those children who have asthma at school age. Thus a focus on early changes in ASM might be important in understanding the subsequent development of childhood asthma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asthma / diagnosis*
  • Asthma / immunology
  • Asthma / pathology*
  • Biopsy
  • Bronchi / immunology
  • Bronchi / pathology*
  • Bronchoscopy
  • Child
  • Child, Preschool
  • Early Diagnosis
  • Eosinophils / immunology
  • Eosinophils / pathology
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Mast Cells / immunology
  • Mast Cells / pathology
  • Muscle, Smooth / immunology
  • Muscle, Smooth / pathology*
  • Respiratory Function Tests
  • Respiratory Mucosa / immunology
  • Respiratory Mucosa / pathology
  • Respiratory Sounds / immunology
  • Respiratory Sounds / physiopathology*