Airway epithelium and structural cells
The respiratory system airway epithelium has defence mechanisms to
protect itself. The physical barrier that stops penetration by inhaled
microbes/allergens is maintained by intercellular epithelial junctions.
Only extremely small particles, less than 3 to 5 microns (0.000118 to
0.000196 inches) in diameter, penetrate to the deep lung. Any compromise
on epithelial integrity predisposes to aeroallergen sensitization and
ongoing inflammation by allergens and microbes.1
The airway epithelial cell innate immune function is however impaired in
children with persistent wheeze compared with healthy children. Airway
remodelling from inflammation increased thickness of the subepithelial
reticular basement membrane, increased airway smooth muscle
angiogenesis. The airway remodelling linked with abnormal lung function
in older children with asthma and likely associated with early lung
function changes.