Thomas Southworth

α,β-Unsaturated aldehydes contained in cigarette smoke elicit IL-8 release in pulmonary cells through mitogen-activated protein kinases

Cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD), a syndrome characterized by pulmonary neutrophil infiltration, chronic inflammation, and progressive tissue destruction. We examined here the acute effect of aqueous cigarette smoke extract (CSE) and of two alpha,beta-unsaturated aldehydes (acrolein and crotonaldehyde) contained in CSE in cultured normal human lung fibroblasts and small airway epithelial cells. By examining a panel of 19 cytokines and chemokines, we found that IL-8 release was elevated by CSE as well as by acrolein, whereas other inflammatory mediators were mostly unaffected. CSE-evoked IL-8 release was mimicked by acrolein and crotonaldehyde at concentrations (3-60 microM each) found in CSE and fully prevented by 1 mM alpha,beta-unsaturated aldehydes scavengers N-acetylcysteine (NAC) or sodium 2-mercaptoethanesulfonate. Neither the saturated aldehyde acetaldehyde nor H(2)O(2) evoked IL-8 release. In addition, CSE or crotonaldehyde upregulated the release of IL-8 from alveolar macrophages from both COPD patients and healthy nonsmokers, indicating that this is a response common to cells involved in lung inflammation. CSE-evoked IL-8 release was accompanied by increased phosphorylation of p38 MAPK and ERK1/2. CSE-evoked p38 and ERK1/2 phosphorylation was mimicked by acrolein and inhibited by NAC. IL-8 release elicited by both acrolein and CSE was blocked by pharmacological inhibition of p38 and ERK1/2 phosphorylation. In summary, our data show that alpha,beta-unsaturated aldehydes-evoked phosphorylation of p38 and ERK1/2 underlies IL-8 release elicited by CSE, thus shedding light on the mechanisms through which cigarette smoke can initiate inflammation in the lung.

IFN-γ synergistically enhances LPS signalling in alveolar macrophages from COPD patients and controls by corticosteroid-resistant STAT1 activation.

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).

The effects of corticosteroids on COPD lung macrophages: a pooled analysis

BackgroundThere is large variation in the therapeutic response to inhaled corticosteroids (ICS) in COPD patients. We present a pooled analysis of our previous studies investigating the effects of corticosteroids on lung macrophages, in order to robustly determine whether corticosteroid sensitivity in COPD cells is reduced compared to controls, and also to evaluate the degree of between individual variation in drug response.MethodsData from 20 never smokers (NS), 27 smokers (S) and 45 COPD patients was used. Lung macropahges had been stimulated with lipopolysaccharide (LPS), with or without the corticosteroid dexamethasone, and tumour necrosis factor (TNF)-α, interleukin (IL)-6 and chemokine C-X-C motif ligand (CXCL) 8 production was measured.ResultsThere was no difference in the anti-inflammatory effects of corticosteroids when comparing group mean data of COPD patients versus controls. The inhibition of TNF-α and IL-6 was greater than CXCL8. The effects of corticosteroids varied considerably between subjects, particularly at lower corticosteroid concentrations.ConclusionsWe confirm that overall corticosteroid sensitivity in COPD lung macrophages is not reduced compared to controls. The varied effect of corticosteroids between subjects suggests that some individuals have an inherently poor corticosteroid response. The limited suppression of lung macrophage derived CXCL8 may promote neutrophilic inflammation in COPD.

Reduced exhaled breath condensate pH in asthmatic smokers using inhaled corticosteroids.

Background and objectives:  Exhaled breath condensate (EBC) pH has been proposed as a biomarker of airway inflammation and oxidative stress in asthma. Cigarette smoking reduces EBC pH in mild asthma. The effects of smoking on EBC pH in more symptomatic asthmatic patients using inhaled corticosteroids (ICS) are unknown. We aimed to compare EBC pH in asthmatic smokers (AS) and non‐smokers (ANS) with moderate to severe disease, who were taking ICS. We also investigated the relationship between EBC pH and biomarkers of airway inflammation and oxidative stress.

The effects of smoking on the lipopolysaccharide response and glucocorticoid sensitivity of alveolar macrophages of patients with asthma.

BACKGROUND Cigarette smoking in asthma patients causes insensitivity to inhaled glucocorticoids (GCs). We tested the hypothesis that smoking causes GC insensitivity in alveolar macrophages (AMs) obtained from patients with asthma. METHODS Nineteen asthmatic nonsmokers (ANSs) and 13 asthmatic smokers (ASMs) underwent BAL. AMs were cultured with or without dexamethasone, 0.1 to 1,000 nmol/L, for 2 h before lipopolysaccharide (LPS) [1 microg/mL] stimulation. After 6 h, supernatants were harvested for enzyme-linked immunosorbent assay, and messenger RNA was collected for real-time (RT)-polymerase chain reaction (PCR). RESULTS ASMs had higher numbers of AMs per milliliter of BAL fluid than ANSs (1.98 vs 0.75 x 10(6) cells/mL, respectively; p = 0.007). Cigarette smoking significantly attenuated the LPS response for all three cytokines tested among ANSs vs ASMs (tumor necrosis factor [TNF]-alpha, 31.6 vs 10.6 ng/mL, respectively (p = 0.01); interleukin [IL]-6, 25.8 vs 10.8 ng/mL, respectively (p = 0.002); IL-8, 62.5 vs 36.1 ng/mL, respectively (p = 0.001)). There was no difference in dexamethasone dose-response curves between ANSs and ASMs (p > 0.05 for all comparisons). The inhibitory concentration of 50% (IC(50)) for IL-6 was 120.6 vs 83.3, respectively, and for TNF-alpha it was 4.9 vs 8.6, respectively; an IC(50) was not achieved for IL-8. RT-PCR also showed no difference in the suppression of cytokine messenger RNA levels between groups, with IL-8 being the most GC-insensitive cytokine. CONCLUSION Cigarette smoking in patients with asthma increases the number of airway AMs and attenuates their response to LPS, which may have implications in host immune function. Cigarette smoking does not alter the GC sensitivity of AMs in patients with asthma. There was differential cytokine sensitivity, with IL-8 being the least GC-sensitive cytokine. GC-insensitive IL-8 production from AMs may be a mechanism by which neutrophils are attracted into the airways.

Anti-inflammatory potential of PI3Kδ and JAK inhibitors in asthma patients.

BackgroundPhosphatidylinositol 3-kinase delta (PI3Kδ) and Janus-activated kinases (JAK) are both novel anti-inflammatory targets in asthma that affect lymphocyte activation. We have investigated the anti-inflammatory effects of PI3Kδ and JAK inhibition on cytokine release from asthma bronchoalveolar lavage (BAL) cells and T-cell activation, and measured lung PI3Kδ and JAK signalling pathway expression.MethodCells isolated from asthma patients and healthy subjects were treated with PI3Kδ or JAK inhibitors, and/or dexamethasone, before T-cell receptor stimulation. Levels of IFNγ, IL-13 and IL-17 were measured by ELISA and flow cytometry was used to assess T-cell activation. PI3Kδ, PI3Kγ, phosphorylated protein kinase B (pAKT) and Signal Transducer and Activator of Transcription (STAT) protein expression were assessed by immunohistochemistry in bronchial biopsy tissue from asthma patients and healthy subjects. PI3Kδ expression in BAL CD3 cells was measured by flow cytometry.ResultsJAK and PI3Kδ inhibitors reduced cytokine levels from both asthma and healthy BAL cells. Combining dexamethasone with either a JAK or PI3Kδ inhibitor showed an additive anti-inflammatory effect. JAK and PI3Kδ inhibitors were shown to have direct effects on T-cell activation. Immunohistochemistry showed increased numbers of PI3Kδ expressing cells in asthma bronchial tissue compared to controls. Asthma CD3 cells in BAL expressed higher levels of PI3Kδ protein compared to healthy cells.ConclusionsTargeting PI3Kδ or JAK may prove effective in reducing T-cell activation and the resulting cytokine production in asthma.

Characterization of the inflammatory response to inhaled lipopolysaccharide in mild to moderate chronic obstructive pulmonary disease

AIMS Lipopolysaccharide (LPS) inhalation causes increased airway and systemic inflammation. We investigated LPS inhalation in patients with chronic obstructive pulmonary disease (COPD) as a model of bacterial exacerbations. We studied safety, changes in sputum and systemic biomarkers. We have also investigated interleukin (IL)-17 concentrations in this model. METHODS Twelve COPD patients inhaled 5 μg LPS. Safety was monitored over 24 h. Sputum was induced at baseline, 6 and 24 h for cells and IL-8, IL-17, neutrophil elastase, monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1β (MIP-1β) in supernatants. Serum was collected at baseline, 4, 8 and 24 h for IL-6, C-reactive protein (CRP) and Clara cell protein (CC-16) concentrations. Peripheral blood mononuclear cells (PBMCs) were isolated at baseline and 4 h for systemic IL-17 analysis. RESULTS LPS 5 μg was well tolerated. The greatest FEV1 change was 11.7% (mean) at 1 h (95% CI 5.1-18.2%). There was a large range in maximal fall (2.5-37.7%). Total sputum cell count and neutrophil count significantly increased 6 and 24 h post-LPS. There was no change in sputum supernatant mediators. IL-6, CRP and CC-16 increased post-inhalation, with different temporal patterns. CD4+ and CD8+ cell associated IL-17 significantly increased at 4 h. CONCLUSIONS Inhaled LPS in COPD patients safely causes increased airway and systemic inflammation. This may be a model for studying COPD exacerbations.

The effect of phosphatidylinositol-3 kinase inhibition on matrix metalloproteinase-9 and reactive oxygen species release from chronic obstructive pulmonary disease neutrophils.

BACKGROUND Chronic Obstructive Pulmonary Disease (COPD) is characterised by increased neutrophilic inflammation. A potential novel anti-inflammatory target in COPD is phosphatidylinositol-3 kinase (PI3 kinase), which targets neutrophil function. This study evaluated the effects of selective PI3Kδ inhibition on COPD blood and sputum neutrophils both in the stable state and during exacerbations. METHODS Blood and sputum neutrophils from stable and exacerbating COPD patients were cultured with the corticosteroid dexamethasone, a pan PI3 kinase inhibitor (ZSTK474), a δ selective PI3 kinase inhibitor (GSK045) and a p38 mitogen activated protein (MAP) kinase inhibitor (BIRB 796); matrix metalloproteinase (MMP)-9 and reactive oxygen species (ROS) release were analysed. RESULTS PI3Kδ inhibition significantly reduced MMP-9, intracellular ROS and extracellular ROS release from blood neutrophils (45.6%, 30.1% and 47.4% respectively; p<0.05) and intracellular ROS release from sputum neutrophils (16.6%; p<0.05) in stable patients. PI3Kδ selective inhibition significantly reduced stimulated MMP-9 (36.4%; p<0.05) and unstimulated and stimulated ROS release (12.6 and 26.7%; p<0.05) from blood neutrophils from exacerbating patients. The effects of the p38 MAP kinase inhibitor and dexamethasone in these experiments were generally lower than PI3Kδ inhibition. CONCLUSION PI3Kδ selective inhibition is a potential strategy for targeting glucocorticoid insensitive MMP-9 and ROS secretion from COPD neutrophils, both in the stable state and during exacerbations.

Clinical characteristics of eosinophilic COPD versus COPD patients with a history of asthma

Eosinophilic COPD appears to be a distinct patient subgroup with an increased corticosteroid response. Eosinophilic COPD has been labelled as part of the asthma COPD overlap syndrome (ACOS). We compared the clinical characteristics of eosinophilic COPD patients (without any clinical history of asthma) and COPD patients with a childhood history of asthma. COPD patients with asthma were characterised by more allergies and more exacerbations, but less eosinophilic inflammation. While terms such as “ACOS” are used to “lump” patients together, we report distinct differences between eosinophilic COPD and COPD patients with asthma, and propose that these groups should be split rather than lumped.

CRTH2 antagonists in asthma: current perspectives

Chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) binds to prostaglandin D2. CRTH2 is expressed on various cell types including eosinophils, mast cells, and basophils. CRTH2 and prostaglandin D2 are involved in allergic inflammation and eosinophil activation. Orally administered CRTH2 antagonists are in clinical development for the treatment of asthma. The biology and clinical trial data indicate that CRTH2 antagonists should be targeted toward eosinophilic asthma. This article reviews the clinical evidence for CRTH2 involvement in asthma pathophysiology and clinical trials of CRTH2 antagonists in asthma. CRTH2 antagonists could provide a practical alternative to biological treatments for patients with severe asthma. Future perspectives for this class of drug are considered, including the selection of the subgroup of patients most likely to show a meaningful treatment response.