Background: The relationship between airway structural changes and inflammation is unclear in early cystic fibrosis (CF) lung disease. Objective: To determine changes of airway remodelling in children with CF, compared with appropriate disease and healthy controls.
Methods: Bronchoalveolar lavage and endobronchial biopsy were performed in a cross-sectional study of 43 children with CF (aged 0.3 to 16.8 years), 7 children with primary ciliary dyskinesia (PCD), 26 children with chronic respiratory symptoms (CRS) investigated for recurrent infection and/or cough, and 7 control children with no lower airway symptoms. Inflammatory cells, cytokines, proteases and matrix constituents were measured in bronchoalveolar lavage fluid (BALF). Reticular basement membrane (RBM) thickness was measured on biopsies using light microscopy.
Results: Increased concentrations of elastin, glycosaminoglycans and collagen were found in CF BALF compared to the CRS group and controls, and each correlated with elastase activity, MMP-9 and neutrophil concentration. Levels of inflammatory markers and matrix components were similar in the PCD and CF groups. In the CF group, both elastin concentration and MMP-9:TIMP-1 ratio, correlated negatively with FEV1 (r=-0.45, p<0.05 and r=-0.47, p<0.05 respectively). Median RBM thickness was greater in the CF group (5.9 mm) than controls (4.0 mm, p<0.01), and correlated with transforming growth factor-β1 (TGF-β1) concentration (r=0.53, p=0.01); however, there was no correlation with pulmonary function.
Conclusions: This study provides evidence for two forms of airway remodelling in children with CF: firstly, matrix breakdown which correlates with proteases and pulmonary function, and secondly RBM thickening, related to TGF-β1 concentration.
- cystic fibrosis
- extracellular matrix