IL-17A and Serum Amyloid A Are Elevated in a Cigarette Smoke Cessation Model Associated with the Persistence of Pigmented Macrophages, Neutrophils and Activated NK Cells: e113180

• Published in: PloS one Vol. 9; no. 11
• Main Authors: Hansen, Michelle J, Chan, Sheau PyngJ, Langenbach, Shenna Y, Dousha, Lovisa F, Jones, Jessica E, Yatmaz, Selcuk, Seow, Huei Jiunn, Vlahos, Ross, Anderson, Gary P, Bozinovski, Steven
• Format: Journal Article
• Language: English
• Published: 01.11.2014
• ISSN: 1932-6203
• DOI: 10.1371/journal.pone.0113180

While global success in cessation advocacy has seen smoking rates fall in many developed countries, persistent lung inflammation in ex-smokers is an increasingly important clinical problem whose mechanistic basis remains poorly understood. In this study, candidate effector mechanisms were assessed in mice exposed to cigarette smoke (CS) for 4 months following cessation from long term CS exposure. BALF neutrophils, CD4+ and CD8+ T cells and lung innate NK cells remained significantly elevated following smoking cessation. Analysis of neutrophil mobilization markers showed a transition from acute mediators (MIP-2 alpha , KC and G-CSF) to sustained drivers of neutrophil and macrophage recruitment and activation (IL-17A and Serum Amyoid A (SAA)). Follicle-like lymphoid aggregates formed with CS exposure and persisted with cessation, where they were in close anatomical proximity to pigmented macrophages, whose number actually increased 3-fold following CS cessation. This was associated with the elastolytic protease, MMP-12 (macrophage metallo-elastase) which remained significantly elevated post-cessation. Both GM-CSF and CSF-1 were significantly increased in the CS cessation group relative to the control group. In conclusion, we show that smoking cessation mediates a transition to accumulation of pigmented macrophages, which may contribute to the expanded macrophage population observed in COPD. These macrophages together with IL-17A, SAA and innate NK cells are identified here as candidate persistence determinants and, we suggest, may represent specific targets for therapies directed towards the amelioration of chronic airway inflammation.