Comparison of airway mucin 5AC and mucin 5B expression in preterm-born adults and asthma

Background Since preterm birth is a risk factor for developing chronic lung disease later in life and has been associated with asthma-like symptoms, we hypothesized that preterm-born adults with and without a history of bronchopulmonary dysplasia (BPD) resemble patients with asthma with respect to altered mucin expression in the airways. Methods Bronchial biopsies were retrieved from 39 adults born very-to-extremely preterm of which 22 had a history of BPD, 18 patients with mild allergic asthma, and 24 healthy controls. Mucin (MUC) 5AC and MUC5B protein expressions were determined by immunohistochemistry and immunoelectron microscopy. Additionally, the percentage of goblet cells was estimated. Results MUC5AC expression and the percentage of goblet cells were lower in preterm-born adults than in asthma patients but did not markedly differ from those of healthy controls. In the preterm-born adults, MUC5AC expression correlated negatively with forced expiratory volume in one second to forced vital capacity ratio (FEV 1 /FVC) and positively with St George's Respiratory Questionnaire scores. Preterm-born adults with high MUC5AC expression had more bronchial hyperreactivity than those with low expression. MUC5B expression was lower in preterm-born adults with bronchial hyperreactivity and higher in those who reported having phlegm compared to those who did not have these signs. Conclusions Unlike patients with asthma, preterm-born adults with or without BPD do not exhibit increased MUC5AC expression compared to healthy controls. However, the associations of MUC5AC and MUC5B expression with lung function, symptoms and quality of life indices suggest a potential clinical role for these mucins in this population.