title: IFN-γ synergistically enhances LPS signalling in alveolar macrophages from COPD patients and controls by corticosteroid-resistant STAT1 activation.
abstract: OBJECTIVE
  IFN-γ levels are increased in chronic obstructive airway disease (COPD) patients compared with healthy subjects and are further elevated during viral exacerbations. IFN-γ can 'prime' macrophages to enhance the response to toll-like receptor (TLR) ligands, such as LPS. The aim of this study was to examine the effect IFN-γ on corticosteroid sensitivity in alveolar macrophages (AM).
  
  
  METHODS
  AM from non-smokers, smokers and COPD patients were stimulated with IFN-γ and/or LPS with or without dexamethasone. IL-6, TNF-α and IFN-γ-induced protein 10 kDa (IP-10) levels were measured by elisa, and Western blots were used to investigate the IFN-γ-stimulated Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling pathway. Real-time PCR and flow cytometry were used to investigate TLR levels following IFN-γ treatment.
  
  
  RESULTS
  In all three subject groups, IFN-γ alone had no effect on IL-6 and TNF-α production but enhanced the effects of LPS on these cytokines. In contrast, IFN-γ alone increased the production of IP-10. IFN-γ increased TLR2 and TLR4 expression in AM. Cytokine induction and STAT1 activation by IFN-γ were insensitive to dexamethasone for all groups. The inhibition of JAK and STAT1 repressed all these IFN-γ effects.
  
  
  CONCLUSIONS
  Our results demonstrate that IFN-γ-induced STAT-1 signalling is corticosteroid resistant in AMs, and that targeting IFN-γ signalling by JAK inhibitors is a potentially novel anti-inflammatory strategy in COPD.
authors.affiliation: Manchester Academic Health Centre, NIHR Translational Research Facility, University Hospital of South Manchester Foundation Trust, Manchester, UK. thomas.southworth-2@manchester.ac.uk
authors.forename: T
authors.initials: T
authors.lastname: Southworth
authors.forename: A
authors.initials: A
authors.lastname: Metryka
authors.forename: S
authors.initials: S
authors.lastname: Lea
authors.forename: S
authors.initials: S
authors.lastname: Farrow
authors.forename: J
authors.initials: J
authors.lastname: Plumb
authors.forename: D
authors.initials: D
authors.lastname: Singh
mesh_terms: D000305:Adrenal Cortex Hormones / Q000494:pharmacology; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D004351:Drug Resistance; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D053612:Janus Kinases / Q000037:antagonists & inhibitors; D008070:Lipopolysaccharides; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D051195:Toll-Like Receptor 2 / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000235:genetics; D014740:Vidarabine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000305:Adrenal Cortex Hormones; D000893:Anti-Inflammatory Agents; D016207:Cytokines; D008070:Lipopolysaccharides; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D003907:Dexamethasone; D007371:Interferon-gamma; D053612:Janus Kinases; D014740:Vidarabine; C024352:fludarabine