RT Journal Article
SR Electronic
T1 Delayed neutrophil apoptosis enhances NET formation in cystic fibrosis
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 134
OP 144
DO 10.1136/thoraxjnl-2017-210134
VO 73
IS 2
A1 Robert D Gray
A1 Gareth Hardisty
A1 Kate H Regan
A1 Maeve Smith
A1 Calum T Robb
A1 Rodger Duffin
A1 Annie Mackellar
A1 Jennifer M Felton
A1 Lily Paemka
A1 Brian N McCullagh
A1 Christopher D Lucas
A1 David A Dorward
A1 Edward F McKone
A1 Gordon Cooke
A1 Seamas C Donnelly
A1 Pradeep K Singh
A1 David A Stoltz
A1 Christopher Haslett
A1 Paul B McCray
A1 Moira K B Whyte
A1 Adriano G Rossi
A1 Donald J Davidson
YR 2018
UL http://thorax.bmj.com/content/73/2/134.abstract
AB Background Cystic fibrosis (CF) lung disease is defined by large numbers of neutrophils and associated damaging products in the airway. Delayed neutrophil apoptosis is described in CF although it is unclear whether this is a primary neutrophil defect or a response to chronic inflammation. Increased levels of neutrophil extracellular traps (NETs) have been measured in CF and we aimed to investigate the causal relationship between these phenomena and their potential to serve as a driver of inflammation. We hypothesised that the delay in apoptosis in CF is a primary defect and preferentially allows CF neutrophils to form NETs, contributing to inflammation.Methods Blood neutrophils were isolated from patients with CF, CF pigs and appropriate controls. Neutrophils were also obtained from patients with CF before and after commencing ivacaftor. Apoptosis was assessed by morphology and flow cytometry. NET formation was determined by fluorescent microscopy and DNA release assays. NET interaction with macrophages was examined by measuring cytokine generation with ELISA and qRT-PCR.Results CF neutrophils live longer due to decreased apoptosis. This was observed in both cystic fibrosis transmembrane conductance regulator (CFTR) null piglets and patients with CF, and furthermore was reversed by ivacaftor (CFTR potentiator) in patients with gating (G551D) mutations. CF neutrophils formed more NETs and this was reversed by cyclin-dependent kinase inhibitor exposure. NETs provided a proinflammatory stimulus to macrophages, which was enhanced in CF.Conclusions CF neutrophils have a prosurvival phenotype that is associated with an absence of CFTR function and allows increased NET production, which can in turn induce inflammation. Augmenting neutrophil apoptosis in CF may allow more appropriate neutrophil disposal, decreasing NET formation and thus inflammation.