BackgroundMacrophages have been implicated in the pathogenesis of COPD. M1 and M2 macrophages constitute subpopulations displaying pro- and anti-inflammatory properties. We hypothesized that smoking cessation affects macrophage heterogeneity in the lung of patients with COPD. Our aim was to study macrophage heterogeneity using the M2-marker CD163 and selected pro- and anti-inflammatory mediators in bronchoalveolar lavage (BAL) fluid and induced sputum from current smokers and ex-smokers with COPD.Methods114 COPD patients (72 current smokers; 42 ex-smokers, median smoking cessation 3.5 years) were studied cross-sectionally and underwent sputum induction (M/F 99/15, age 62 ± 8 [mean ± SD] years, 42 (31-55) [median (range)] packyears, post-bronchodilator FEV1 63 ± 9% predicted, no steroids past 6 months). BAL was collected from 71 patients. CD163+ macrophages were quantified in BAL and sputum cytospins. Pro- and anti-inflammatory mediators were measured in BAL and sputum supernatants.ResultsEx-smokers with COPD had a higher percentage, but lower number of CD163+ macrophages in BAL than current smokers (83.5% and 68.0%, p = 0.04; 5.6 and 20.1 ×104/ml, p = 0.001 respectively). The percentage CD163+ M2 macrophages was higher in BAL compared to sputum (74.0% and 30.3%, p < 0.001). BAL M-CSF levels were higher in smokers than ex-smokers (571 pg/ml and 150 pg/ml, p = 0.001) and correlated with the number of CD163+ BAL macrophages (Rs = 0.38, p = 0.003). No significant differences were found between smokers and ex-smokers in the levels of pro-inflammatory (IL-6 and IL-8), and anti-inflammatory (elafin, and Secretory Leukocyte Protease Inhibitor [SLPI]) mediators in BAL and sputum.ConclusionsOur data suggest that smoking cessation partially changes the macrophage polarization in vivo in the periphery of the lung towards an anti-inflammatory phenotype, which is not accompanied by a decrease in inflammatory parameters.

Bronchial hyperresponsiveness (BHR) is regarded as a hallmark of asthma, yet it is also present in a considerable number of chronic obstructive pulmonary disease (COPD) patients. Epidemiological studies have shown that BHR provides complementary information to forced expiratory volume in 1 s (FEV1) for development and progression of COPD. We hypothesised that the severity of BHR and its longitudinal changes associate with both clinical and airway inflammation measures in COPD.Our hypothesis was tested in 114 COPD patients (median age 62.9 years, smoking exposure 45.9 pack-yrs) participating in the GLUCOLD (Groningen Leiden Universities Corticosteroids in Obstructive Lung Disease) study, which previously showed an improvement in BHR with fluticasone and fluticasone/salmeterol. At baseline, and 6 and 30 months after treatment, we investigated lung function, including body plethysmography, provocative concentration of methacholine causing a 20% fall in FEV1, sputum induction, and bronchial biopsies.By performing both cross-sectional and longitudinal analyses, we show that BHR in COPD is predominantly associated with residual volume/total lung capacity (a measure of air trapping) and airway inflammation reflected by the number of neutrophils, macrophages and lymphocytes in sputum and bronchial biopsies.Our findings indicate that BHR is an independent trait in COPD and provides important information on phenotype heterogeneity and disease activity.

AHR is common in patients with mild-to-moderate COPD, affecting 1 in 4 patients and identifies a distinct subset of patients who have increased risk of disease progression and mortality. AHR may represent a spectrum of the asthma-COPD overlap phenotype that urgently requires disease modification.

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