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- PMID: 22352763
- UKPMCID: 22352763
- DOI: 10.1111/j.1476-5381.2012.01907.x
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IFN-γ synergistically enhances LPS signalling in alveolar macrophages from COPD patients and controls by corticosteroid-resistant STAT1 activation.
Southworth, T; Metryka, A; Lea, S; Farrow, S; Plumb, J; Singh, D
British journal of pharmacology. 2012;166(7):2070-83.
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Full-text held externally
- PMID: 22352763
- UKPMCID: 22352763
- DOI: 10.1111/j.1476-5381.2012.01907.x
Abstract
BACKGROUND AND PURPOSE: 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). EXPERIMENTAL APPROACH: 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. KEY 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 AND IMPLICATIONS: 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.