Alpha-1 antitrypsin genotype and Pseudomonas aeruginosa chronic airway infection in bronchiectasis patients

<bold>Background:</bold> Alpha-1 antitrypsin (A1AT) plays a fundamental role in bronchial inflammation and in defence against respiratory infections. The role of A1AT in the pathophysiology of bronchiectasis is not completely understood. In this regard, we aimed to assess the impact of A1AT genotype in bronchiectasis patients. <bold>Methods:</bold> Prospective pilot study including bronchiectasis patients from a monographic clinic. All participants were clinically stable, and individuals with a primary diagnosis of COPD, known A1AT deficit or not able to produce sputum samples were excluded. Clinical data, sputum and blood samples were collected. Saliva was obtained for A1AT genotyping of the SERPINA1 gene. Participants were categorized according to the presence of genetic variants. <bold>Results:</bold> Forty-six patients were included, with a mean age of 62.9 ± 12.5 years. Chronic infection was observed in 34 (73.9%) subjects, and Pseudomonas aeruginosa (PA) was the most common pathogen. 12 (26.1%) participants had A1AT allelic variants. Of them, 11 (91.7%) were M/S, and 1 (8.3%) M/Z. Although A1AT blood levels and disease severity scores were similar between groups, patients with genetic variants showed a higher proportion of PA chronic infection (50% Vs. 91.7%; p=0.042). Moreover, this group also had a higher proportion of subjects with a recent hospitalization due to an exacerbation (0 Vs 25%; p=0.015). <bold>Conclusions:</bold> Bronchiectasis patients with A1AT allelic variants have a higher proportion of PA chronic infection than those with normal gemotype, regardless of A1AT blood levels. This indicates that not only A1AT deficit, but also A1AT genotype may be relevant in the pathophysiology of PA infection in bronchiectasis.