Title Differential neutrophil activation in viral infections: Enhanced TLR-7/8-mediated CXCL8 release in asthma.
Author Tang, Francesca S M; Van Ly, David; Spann, Kirsten; Reading, Patrick C; Burgess, Janette K; Hartl, Dominik; Baines, Katherine J; Oliver, Brian G
Journal Respirology Publication Year/Month 2016-Jan
PMID 26477783 PMCID PMC5324549
Affiliation + expend 1.Woolcock Institute of Medical Research, The University of Sydney, Sydney, New South Wales, Australia.

BACKGROUND AND OBJECTIVE: Respiratory viral infections are a major cause of asthma exacerbations. Neutrophils accumulate in the airways and the mechanisms that link neutrophilic inflammation, viral infections and exacerbations are unclear. This study aims to investigate anti-viral responses in neutrophils from patients with and without asthma and to investigate if neutrophils can be directly activated by respiratory viruses. METHODS: Neutrophils from peripheral blood from asthmatic and non-asthmatic individuals were isolated and stimulated with lipopolysaccharide (LPS) (1 mug/mL), f-met-leu-phe (fMLP) (100 nM), imiquimod (3 mug/mL), R848 (1.5 mug/mL), poly I:C (10 mug/mL), RV16 (multiplicity of infection (MOI)1), respiratory syncytial virus (RSV) (MOI1) or influenza virus (MOI1). Cell-free supernatants were collected after 1 h of neutrophil elastase (NE) and matrix metalloproteinase (MMP)-9 release, or after 24 h for CXCL8 release. RESULTS: LPS, fMLP, imiquimod and R848 stimulated the release of CXCL8, NE and MMP-9 whereas poly I:C selectively induced CXCL8 release only. R848-induced CXCL8 release was enhanced in neutrophils from asthmatics compared with non-asthmatic cells (P < 0.01). RSV triggered the release of CXCL8 and NE from neutrophils, whereas RV16 or influenza had no effect. CONCLUSION: Neutrophils release CXCL8, NE and MMP-9 in response to viral surrogates with R848-induced CXCL8 release being specifically enhanced in asthmatic neutrophils. Toll-like receptor (TLR7/8) dysregulation may play a role in neutrophilic inflammation in viral-induced exacerbations.

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