Lung Inflammation in Alpha-1-Antitrypsin Deficient Individuals with Normal Lung Function

Abstract

Abstract Background: Alpha-1-antitrypsin deficient (AATD) individuals are prone to develop early age of onset chronic obstructive pulmonary disease (COPD) which is more severe than non-genetic COPD. In this study, we investigated the characteristics of lower respiratory tract inflammation in AATD individuals prior to the onset of clinically significant COPD. Methods: Bronchoalveolar lavage was performed on 22 AATD individuals with normal lung function and 14 healthy individuals. Cell counts and concentrations of proteases, alpha-1-antitrypsin, proinflammatory cytokines, and leukotriene B4 were determined in the bronchoalveolar lavage fluid from AATD and healthy individuals. In order to determine the characteristics of airway inflammation in this cohort, we also analyzed immune cell components of the large airways from bronchial biopsies using immunohistochemistry in both study subjects. Finally, we made comparisons between airway inflammation and lung function rate of decline using four repeated lung function tests over one year in AATD individuals. Results: AATD individuals with normal lung function had significantly higher neutrophil counts, levels of proteases, IL-8, IL-6, IL-1b, and leukotriene B4 in their epithelial lining fluid compared to control subjects. A positive correlation was noted between the levels of IL-8, neutrophils, and concentration of neutrophil elastase in epithelial lining fluid of AATD individuals. AATD individuals also showed a negative correlation of baseline FEV1 with neutrophil count, neutrophil elastase, and cytokine levels in epithelial lining fluid. In addition, we found that the airways of AATD individuals have increased lymphocytes, macrophages, neutrophils, and mast cells in epithelial lining fluid compared to control subjects. Conclusion: Inflammation is present in the lower respiratory tract and airways of AATD individuals despite having normal lung function. A declining trend was also noticed in the lung function of AATD individuals which was correlated with inflammatory phenotype of their lower respiratory tract. This results provide new evidence for the presence of early inflammation in the lungs of AATD individuals. This suggests that early anti-inflammatory therapies may be a potential strategy to prevent progression of lung disease in individuals with AATD.