Extracellular DNA, Neutrophil Extracellular Traps, and Inflammasome Activation in Severe Asthma.
Rationale: Extracellular DNA (eDNA) and neutrophil extracellular traps (NETs) are implicated in multiple inflammatory diseases. NETs mediate inflammasome activation and IL-1β secretion from monocytes and cause airway epithelial cell injury, but the role of eDNA, NETs, and IL-1β in asthma is uncertain. Objectives: To characterize the role of activated neutrophils in severe asthma through measurement of NETs and inflammasome activation. Methods: We measured sputum eDNA in induced sputum from 399 patients with asthma in the Severe Asthma Research Program-3 and in 94 healthy control subjects. We subdivided subjects with asthma into eDNA-low and -high subgroups to compare outcomes of asthma severity and of neutrophil and inflammasome activation. We also examined if NETs cause airway epithelial cell damage that can be prevented by DNase. Measurements and Main Results: We found that 13% of the Severe Asthma Research Program-3 cohort is "eDNA-high," as defined by sputum eDNA concentrations above the upper 95th percentile value in health. Compared with eDNA-low patients with asthma, eDNA-high patients had lower Asthma Control Test scores, frequent history of chronic mucus hypersecretion, and frequent use of oral corticosteroids for maintenance of asthma control (all P values <0.05). Sputum eDNA in asthma was associated with airway neutrophilic inflammation, increases in soluble NET components, and increases in caspase 1 activity and IL-1β (all P values <0.001). In in vitro studies, NETs caused cytotoxicity in airway epithelial cells that was prevented by disruption of NETs with DNase. Conclusions: High extracellular DNA concentrations in sputum mark a subset of patients with more severe asthma who have NETs and markers of inflammasome activation in their airways.
['Lachowicz-Scroggins|Marrah E|ME|0000-0002-3173-5662', 'Dunican|Eleanor M|EM|0000-0003-4014-5100', 'Charbit|Annabelle R|AR|', 'Raymond|Wilfred|W|', 'Looney|Mark R|MR|', 'Peters|Michael C|MC|', 'Gordon|Erin D|ED|', 'Woodruff|Prescott G|PG|', 'Lefrançais|Emma|E|', 'Phillips|Brenda R|BR|', 'Mauger|David T|DT|', 'Comhair|Suzy A|SA|', 'Erzurum|Serpil C|SC|', 'Johansson|Mats W|MW|', 'Jarjour|Nizar N|NN|', 'Coverstone|Andrea M|AM|', 'Castro|Mario|M|', 'Hastie|Annette T|AT|', 'Bleecker|Eugene R|ER|', 'Fajt|Merritt L|ML|', 'Wenzel|Sally E|SE|', 'Israel|Elliot|E|', 'Levy|Bruce D|BD|', 'Fahy|John V|JV|']
D000208:Acute Disease D000328:Adult D001249:Asthma D015153:Blotting, Western D016022:Case-Control Studies D004247:DNA D065206:Extracellular Traps D005260:Female D005954:Glucosephosphate Dehydrogenase D006801:Humans D058847:Inflammasomes D015850:Interleukin-6 D016209:Interleukin-8 D008137:Longitudinal Studies D008297:Male D008875:Middle Aged D009504:Neutrophils
extracellular DNA neutrophil extracellular traps asthma IL-1β caspase 1