TY - JOUR T1 - <em>In vitro</em> and <em>in vivo</em> modulation of NADPH-oxidase activity and reactive oxygen species production in human neutrophils by alpha-1 antitrypsin JF - ERJ Open Research JO - erjor DO - 10.1183/23120541.00234-2021 SP - 00234-2021 AU - Padraig Hawkins AU - Thomas McEnery AU - Claudie Gabillard-Lefort AU - David A Bergin AU - Bader Alfawaz AU - Vipatsorn Shutchaidat AU - Paula Meleady AU - Michael Henry AU - Orla Coleman AU - Mark Murphy AU - Noel G. McElvaney AU - Emer P. Reeves Y1 - 2021/01/01 UR - http://openres.ersjournals.com/content/early/2021/09/09/23120541.00234-2021.abstract N2 - Oxidative stress from innate immune cells is a driving mechanism that underlies COPD pathogenesis. Individuals with alpha-1 antitrypsin (AAT) deficiency (AATD) have a dramatically increased risk of developing COPD. To understand this further, the aim of this study was to investigate whether AATD presents with altered neutrophil NADPH-oxidase activation, due to the specific lack of plasma AAT. Experiments were performed using circulating neutrophils isolated from healthy controls and individuals with AATD. Superoxide anion (O2−) production was determined from the rate of reduction of cytochrome c. Quantification of membrane NADPH-oxidase subunits was performed by mass spectrometry and western blot analysis. The clinical significance of our in vitro findings were assessed in patients with AATD and severe COPD receiving intravenous AAT replacement therapy. In vitro, AAT significantly inhibited O2− production by stimulated neutrophils and suppressed receptor stimulation of cyclic adenosimonophosphate (cAMP) and extracellular-signal regulated kinase (ERK)1/2 phosphorylation. In addition, AAT reduced plasma membrane translocation of cytosolic phox components of the NADPH-oxidase. Ex vivo, AATD neutrophils demonstrated increased plasma membrane associated p67phox and p47phox and significantly increased O2− production. The described variance in phox protein membrane assembly was resolved post AAT augmentation therapy in vivo, the effects of which significantly reduced AATD neutrophil O2− production to that of healthy control cells. These results expand our knowledge on the mechanism of neutrophil driven airways disease associated with AATD. Therapeutic AAT augmentation modified neutrophil NADPH-oxidase assembly and ROS production, with implications for clinical use in conditions in which oxidative stress plays a pathogenic role.FootnotesThis manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.Conflicts of Interest: Noel G. McElvaney reports support for the present manuscript from US Alpha One Foundation.Conflicts of Interest: Emer Reeves reports support for the present manuscript from the Medical Research Charities Group/Health Research Board Joint Funding Scheme (MRCG-2018-04). ER -