Lipid-laden bronchoalveolar macrophages in asthma and chronic cough.

BACKGROUND: The presence of lipids in alveolar macrophages (AMs) may impair their phagocytic response, and determine airway inflammation and obstruction. OBJECTIVE: To determine the factors such as severity of asthma, chronic cough, airway inflammation and obesity that may influence the presence of lipids in lung macrophages. METHODS: Bronchoalveolar lavage fluid (BALF) was obtained from 38 asthmatics (21 severe and 17 mild/moderate), 16 subjects with chronic cough and 11 healthy control subjects. The presence of lipids in macrophages was detected using an Oil-red-O stain and an index of lipid-laden macrophages (LLMI) was obtained. RESULTS: LLMI scores were higher in healthy subjects (median 48 [IQR 10-61]) and the severe asthma group (37 [11.5-61]) compared to mild/moderate asthmatics (7 [0.5-37]; p < 0.05 each). Subjects reporting a history of gastro-oesophageal reflux disease (GORD) had higher LLMI values (41.5 [11.3-138] versus 13 [0-39.3], p = 0.02). There was no significant correlation between LLMI and chronic cough, BAL cell differential counts, FEV1, FEV1/FVC or body mass index (BMI). CONCLUSIONS: The reduced LLMI in mild/moderate asthma may be related to lower incidence of GORD. However, this was not related to the degree of airflow obstruction, obesity or airway inflammation.

A novel macrolide/fluoroketolide, solithromycin (CEM-101), reverses corticosteroid insensitivity via phosphoinositide 3-kinase pathway inhibition.

BACKGROUND AND PURPOSE: Corticosteroid insensitivity is a major therapeutic problem for some inflammatory diseases including chronic obstructive pulmonary disease (COPD), and it is known to be induced by reduced histone deacetylase (HDAC)-2 activities via activation of the phosphoinositide 3-kinase (PI3K) pathway. The aim of this study is to evaluate effects of a novel macrolide/fluoroketolide, solithromycin (SOL, CEM-101), on corticosteroid sensitivity induced by oxidative stress. EXPERIMENTAL APPROACH: Corticosteroid sensitivity was determined by IC50/EC50 of dexamethasone (Dex) on TNF-α-induced CXCL8 production in U937 monocytic cell line and peripheral blood mononuclear cells (PBMC) from COPD patients. Activities of HDAC and protein phosphatase 2A (PP2A) were measured by fluorescence-based assay in cells exposed to hydrogen peroxide (H2O2). We also investigated steroid insensitive airway neutrophilia in cigarette smoke exposed mice in vivo. KEY RESULTS: SOL (10 µM) restored Dex sensitivity in PBMC from COPD patients, H2O2-treated U937 cells and phorbol 12-myristate 13-acetate-differentiated U937 cells. In addition, SOL restored HDAC activity with concomitant inhibition of Akt phosphorylation as surrogate marker of PI3K activation. The inhibition of Akt phosphorylation by SOL was due to increased PP2A phosphatase activity, which was reduced in COPD and oxidative stress model. Other known macrolides, such as eryhthromycin, clarithromycin and azithromycin, were significantly less effective in these responses. In cigarette smoke-exposed mice, SOL (100 mg kg(-1), po) showed significant but weak inhibition of neutrophilia, whereas Dex (10 mg kg(-1), p.o.) showed no such effect. However, a combination of SOL and Dex inhibited neutrophilia by over 50%. CONCLUSIONS AND IMPLICATIONS: SOL has potential as novel therapy for corticosteroid-insensitive diseases such as COPD.

Corticosteroid insensitivity is reversed by formoterol via phosphoinositide-3-kinase inhibition.

BACKGROUND AND PURPOSE: Patients with chronic obstructive pulmonary disease (COPD) show a poor response to corticosteroids, which has been linked to oxidative stress. Here we show that the long-acting ß(2) -agonist formoterol (FM) reversed corticosteroid insensitivity under oxidative stress via inhibition of phosphoinositide-3-kinase (PI3K) signalling. EXPERIMENTAL APPROACH: Responsiveness to corticosteroids dexamethasone (Dex), budesonide (Bud) and fluticasone propionate (FP) was determined, as IC(50) values on TNF-α-induced interleukin 8 release, in U937 monocytic cell line treated with hydrogen peroxide (H(2) O(2) ) or peripheral blood mononuclear cells (PBMCs) from patients with COPD or severe asthma. KEY RESULTS: PBMCs from severe asthma and COPD were less sensitive to Dex compared with those from healthy subjects. Both FM (10(-9) M) and salmeterol (SM, 10(-8) M) reversed Dex insensitivity in severe asthma, but only FM restored Dex sensitivity in COPD. Although H(2) O(2) exposure decreased steroid sensitivity in U937 cells, FM restored responsiveness to Bud and FP while the effects of SM were weaker. Additionally, FM, but not SM, partially inhibited H(2) O(2) -induced PI3Kδ-dependent (PKB) phosphorylation. H(2) O(2) decreased SM-induced cAMP production in U937 cells, but did not significantly affect the response to FM. The reduction of SM effects by H(2) O(2) was reversed by pretreatment with LY294002, a PI3K inhibitor, or IC87114, a PI3Kδ inhibitor. CONCLUSION AND IMPLICATIONS: FM reversed oxidative stress-induced corticosteroid insensitivity and decreased ß(2) adrenoceptor-dependent cAMP production via inhibition of PI3Kδ signalling. FM will be more effective than SM, when combined with corticosteroids, for the treatment of respiratory diseases under conditions of high oxidative stress, such as in COPD.