Structural changes to airway smooth muscle in cystic fibrosis
- Division of Pulmonary and Critical Care Medicine, Department of Medicine and the Cardiovascular Research Institute, University of California San Francisco, USA
- Correspondence to:
Dr P G Woodruff
Box 0130, Moffitt Hospital, 505 Parnassus Ave, San Francisco, CA 94143, USA;
- Received 12 May 2004
- Accepted 19 December 2004
Background: Chronic airway obstruction is characteristic of cystic fibrosis (CF) but there are few studies of airway smooth muscle remodelling in CF.
Methods: Airway smooth muscle content and mean airway smooth muscle cell size were measured by applying design-based stereology to bronchoscopic biopsy specimens obtained from seven subjects with CF and 15 healthy controls.
Results: The smooth muscle content increased by 63% in subjects with CF (mean (SD) 0.173 (0.08) v 0.106 (0.042) mm3 smooth muscle/mm3 submucosa, mean difference −0.067; 95% CI −0.12 to −0.013, p = 0.017) but there was no increase in mean cell size (2705 (351) v 2654 (757) μm3, mean difference −51; 95% CI −687 to 585, p = 0.87).
Conclusions: These findings indicate hyperplasia of airway smooth muscle cells without hypertrophy and suggest that accumulation of airway smooth muscle cells may contribute to airway narrowing and bronchial hyperresponsiveness in CF.
This study was supported by a pilot study grant from the Cystic Fibrosis Research and Development Program, a Cystic Fibrosis Foundation Fellowship Award (SRH), by NIH grants K23 RR17002, and RO1 HL61662 and by the General Clinical Research Center, Moffitt Hospital, UCSF, with funds provided by the NCRR, 5 MO1 RR-00079, US Public Health Service.