A morphometric study of mucins and small airway plugging in cystic fibrosis
- 1Service de Pneumologie and UPRES EA 2511, Université René Descartes, Hôpital Cochin, AP-HP, Paris, France
- 2Laboratoire d’Anatomie Pathologique, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
- 3Cardiovascular Research Institute and Departments of Medicine and Physiology, University of California, San Francisco, California, USA
- Correspondence to:
Dr P-R Burgel
Service de Pneumologie, Hôpital Cochin, Université René Descartes, 27 rue du Faubourg St Jacques, 75 679 Paris Cedex 14, France;
- Received 14 March 2006
- Accepted 16 August 2006
- Published Online First 23 August 2006
Rationale: Little knowledge exists on structural changes and plugging in small airways in cystic fibrosis.
Objective: To characterise the extent of plugging and contribution of secreted mucins to the plugs.
Methods: Small airways in patients with cystic fibrosis at transplantation (n = 18) were compared with control non-smokers (n = 10). Tissue sections were stained with Alcian blue (AB)/periodic acid-Schiff (PAS), for mucins MUC5B and MUC5AC, and for neutrophils and its chemoattractant interleukin (IL) 8. Epidermal growth factor receptor (EGFR) and its ligand pro-transforming growth factor α were also identified using immunohistochemical staining. Epithelial and luminal contents were assessed morphometrically.
Results: Plugs occupying >50% of total luminal volume were found in 147 of 231 (63.6%) airways in patients with cystic fibrosis, but only in 1 of 39 (2.6%) airways in controls. In the epithelium of patients with cystic fibrosis, AB/PAS, MUC5B, and MUC5AC-stained volume densities were increased 10-fold (p<0.01), indicating increased mucin production. In airway lumens, staining for mucins was also increased in cystic fibrosis, indicating increased mucin secretion. In the epithelium of patients with cystic fibrosis, neutrophil numbers were markedly increased and were inversely correlated with volume densities of mucous glycoconjugates (r = −0.66, p<0.005). IL8 staining was increased in the epithelium of patients with cystic fibrosis and colocalised with mucins. Staining for EGFR and for pro-transforming growth factor α were increased in the epithelium of patients with cystic fibrosis; positive correlations were found between EGFR-stained volume density and both AB/PAS and IL8-stained volume densities.
Conclusions: Most of the small airways are plugged in cystic fibrosis at the time of transplantation. Mucins contribute to airway plugging. Recruited neutrophils may be involved in mucin secretion in the plugs. Increased expression of EGFR and its ligand suggests roles in mucin synthesis and neutrophil recruitment.
- AB/PAS, Alcian blue/periodic acid-Schiff
- EGFR, epidermal growth factor receptor
- TGF, transforming growth factor
↵* These authors contributed equally to this work.
Published Online First 23 August 2006
This work was funded by grants from “Chancellerie des Universités de Paris (Leg Poix)” and “Association Vaincre la Mucoviscidose”. DM received educational grants from Association Cardif and Fonds d’Etude et de Recherche du Corps Médical des Hôpitaux de Paris.
Competing interests: None.
An abstract of this work was presented at the 2005 ATS meeting, May, San Diego, California, USA.