Why do some adults with PiMZ α1-antitrypsin develop bronchiectasis? [corrected]

Abstract

Recurrent infections of the upper airways in early life may be a warning sign of inherited α₁-antitrypsin deficiency http://ow.ly/iJsF300kbyV.

FIGURE 1

Characterisation of neutrophils and MZ α₁-antitrypsin (α₁-AT) protein isolated from a PiMZ patient with bronchiectasis. a) High-resolution computed tomography scan of the chest. Image shows bronchiectasis in both lower lobes. b) Characterisation of blood purified PiMZ neutrophil morphology. Cells were deposited onto slides using a Cytospin 3 cytocentrifuge (ThermoFisher Scientific, Waltham, MA, USA), stained with May–Grünwald Giemsa and analysed by light microscopy. Neutrophils had typical features with appropriate diameter, light blue grey cytoplasm and multi-lobed nucleus. c, d) Molecular profiling of α₁-AT proteins. Equal amounts of α₁-AT (Zemaira; CSL Behring, Kankakee, IL, USA) and affinity purified MM and MZ A1AT proteins were analysed on 7.5% SDS-PAGE followed by Western blotting. Total α₁-AT and polymers of α₁-AT were detected using rabbit polyclonal anti-human α₁-AT antibody (dilution of 1:1000) and mouse monoclonal antibody against human α₁-AT polymers (2C1, dilution of 1:700). Polymeric forms of MM and MZ α₁-AT were detected with 2C1 antibody. e–g) Gene expression profiling of purified neutrophils. Neutrophils from three PiMM donors and a PiMZ patient were incubated alone or with 20 ng·mL⁻¹ of lipopolysaccharide (LPS) for 5 h. e and f) Independent of the experimental conditions, PiMZ neutrophils showed lower SERPINA1 and higher ELANE expression relative to PiMM neutrophils. g) In response to LPS, the expression of tumour necrosis factor (TNF)-α was very low whereas interleukin (IL)-1β was twice as higher in PiMZ than PiMM neutrophils. Bars represent the mean±sd of three independent experiments, each with four repeats for PiMM neutrophils, and one experiment with six repeats for PiMZ neutrophils. h and i) Effects of purified MM and MZ α₁-AT on peripheral blood mononuclear cells. Cells were treated with LPS (100 ng·mL⁻¹) alone or in combination with α₁-AT (0.5 mg·mL⁻¹) proteins. When compared to MM, MZ α₁-AT showed significantly lower inhibitory effect on LPS-induced TNF-α and IL-1β expression. Each bar represents mean±sd of three independent repeats. Significance was considered at >0.05.