Airway basement membrane thickness in children with asthma

Background:Asthma is characterized by chronic airway inflammation involving mainly increased numbers of eosinophils, mast cells and T-lymphocytes. “Airway remodeling” refers to structural changes, one of which is thickening of reticular basement membrane (RBM). Aim: To assess whether RBM thickness is associated with age, atopic status, lung function and other parameters in asthmatic children. Methods:Fifteen children with asthma underwent bronchoscopy and bronchial mucosa biopsy. Formalin fixed, paraffin-embedded tissues of the bronchial biopsies were used for the measurement of RBM thickness with the micrometric lens adjusted on photomicroscope. Immunohistochemistry was performed on paraffin section for the detection of B- cell [CD20/L-26] and T-cell [CD3/PS-1] markers. Atopic status was assessed by measuring total IgE and specific IgE antibodies to common allergens. Results:Fifteen children (7 atopic, 8 non- atopic) with asthma were studied, aged 5-11 years. RBM thickness ranged from 2 to 5μ and was >3μ in 9/15 subjects. There was no difference in RBM thickness between atopic and non-atopic children (p=0.217). Moreover, there was no association of RBM thickness with age (p=0.819), FEV1 (p=0.906), eosinophilia vs no eosinophilia in bronchial mucosa (p=0.402), eosinophilia vs no eosinophilia in blood (p=0.415) and the use of inhaled corticosteroids (median dose 250-500 mcg fluticazone /24h) (p=0.143). Biopsies of asthmatic children with atopy showed a trend for an increased number of CD3+ T lymphocytes in lamina propria of the bronchial mucosa. Conclusions:In our series, there was no significant correlation of RBM thickness with the severity of asthma, possibly because the most participants had mild to moderate disease.