Sensitization to <em>Aspergillus fumigatus</em> as a risk factor for bronchiectasis in COPD

Abstract

Background: Bronchiectasis–chronic obstructive pulmonary disease (COPD) overlap presents a possible clinical phenotype of COPD, but it is unclear why it develops in a subset of patients. We hypothesized that sensitization to Aspergillus fumigatus ( A fum ) is associated with bronchiectasis in COPD and occurs more frequently in vitamin D-deficient patients. Methods: This observational study investigated sensitization to A fum in an outpatient clinical cohort of 300 COPD patients and 50 (ex-) smoking controls. Total IgE, A fum -specific IgE against the crude extract and against the recombinant antigens and A fum IgG were measured using ImmunoCAP fluoroenzyme immunoassay. Vitamin D was measured by radioimmunoassay, and computed tomography images of the lungs were scored using the modified Reiff score. Results: Sensitization to A fum occurred in 18% of COPD patients compared to 4% of controls ( P =0.0110). In all, 31 COPD patients (10%) were sensitized to the crude extract and 24 patients (8%) had only IgE against recombinant antigens. A fum IgG levels were significantly higher in the COPD group ( P =0.0473). Within COPD, A fum -sensitized patients were more often male ( P =0.0293) and more often had bronchiectasis ( P =0.0297). Pseudomonas aeruginosa and Serratia marcescens were more prevalent in historical sputum samples of A fum -sensitized COPD patients compared to A fum -non-sensitized COPD patients ( P =0.0436). Vitamin D levels were comparable ( P =0.2057). Multivariate analysis demonstrated that sensitization to recombinant f1 or f3 had a 2.8-fold increased risk for bronchiectasis ( P =0.0030). Conclusion: These results highlight a potential role for sensitization to A fum in COPD-related bronchiectasis. Keywords: Aspergillus fumigatus hypersensitivity, recombinant antigens, ABPA, vitamin D