Theophylline Restores Histone Deacetylase Activity and Steroid Responses in COPD Macrophages

Chronic obstructive pulmonary disease (COPD) is a common chronic inflammatory disease of the lungs with little or no response to glucocorticoids and a high level of oxidative stress. Histone deacetylase (HDAC) activity is reduced in cells of cigarette smokers, and low concentrations of theophylline can increase HDAC activity. We measured the effect of theophylline on HDAC activity and inflammatory gene expression in alveolar macrophages (AM) from patients with COPD. AM from normal smokers showed a decrease in HDAC activity compared with normal control subjects, and this was further reduced in COPD patients (51% decrease, P < 0.01). COPD AMs also showed increased basal release of IL-8 and TNF-α, which was poorly suppressed by dexamethasone. Theophylline induced a sixfold increase in HDAC activity in COPD AM lysates and significantly enhanced dexamethasone suppression of induced IL-8 release, an effect that was blocked by the HDAC inhibitor trichostatin A. Therefore, theophylline might restore steroid responsiveness in COPD patients

Suppression of GATA-3 Nuclear Import and Phosphorylation: A Novel Mechanism of Corticosteroid Action in Allergic Disease

Peter Barnes and colleagues show that corticosteroids have a potent inhibitory effect on GATA-3 via two interacting mechanisms that suppress Th2 cytokine expression. This novel mechanism of corticosteroid action may help explain the efficacy of corticosteroids in allergic diseases

Fluticasone propionate impairs GATA-3 interaction with importin-α and GATA-3 nuclear localization in vivo and ex vivo.

<p>(A and B) Co-immunoprecipitation analysis of PBMCs from steroid-naïve asthma patients treated with FP in vitro demonstrated impaired interaction between GATA-3 and importin-α measured at 60 min. Each bar represents the mean±SEM of at least three independent experiments; *** <i>p</i><0.001 compared with control as determined by ANOVA/Newman-Keuls analysis. (C and D) Co-immunoprecipitation analyses of PBMCs from steroid-naïve asthma patients treated with inhaled FP (500 µg via a spacer) in vivo demonstrated decreased association between GATA-3 and importin-α. The individual values for each treatment are presented graphically. (E) Representative Western blot showing that importin-α expression was unaffected by inhalation of FP. Blot is representative of gels from three participants.</p

Fluticasone propionate reduces GATA-3 association with importin-α and GATA-3 nuclear import.

<p>(A) Western blot analysis demonstrates a time- (at 10⁻⁸ M FP) and concentration- (at 60 min after stimulation) dependent induction of FP-activated GR interaction with importin-α (Imp-α). A positive control for GR association with importin is shown. Quantification of the densitometry data is shown below. Each bar represents mean±SEM of at least three independent experiments. *** <i>p</i><0.001 compared to control, ^###<i>p</i><0.001. (B) Western blot analysis demonstrated a time- (at 10⁻⁸ M FP) and concentration- (at 60 min after stimulation) dependent induction of FP-activated GR nuclear translocation measured by IP. Quantification of the densitometry data is shown below. Each bar represents mean±SEM of at least three independent experiments. ***<i>p</i><0.001 compared to control. (C) Western blot analysis of HuT-78 cells treated with FP and anti-CD3/CD28 co-stimulation demonstrated a concentration-dependent decrease in GATA-3–importin-α association at 20 min. Quantification of the densitometry data is shown below. Each bar represents mean±SEM of at least three independent experiments. ^###<i>p</i><0.001 compared to control, ***<i>p</i><0.001 compared to αCD3/CD28-stimulated cells. (D) GFP-tagged GATA-3 was overexpressed and cells stimulated (b, c) or not (a) for 30 min with anti-CD3/CD28. The effect of 30 min pretreatment of cells with FP (10⁻⁸ M, c) is also shown. All data were analysed by ANOVA followed by Newman-Keuls post-test.</p

Unbalanced oxidant-induced DNA damage and repair in COPD: a link towards lung cancer

BACKGROUND Chronic obstructive pulmonary disease (COPD) is characterised by oxidative stress and increased risk of lung carcinoma. Oxidative stress causes DNA damage which can be repaired by DNA-dependent protein kinase complex. OBJECTIVES To investigate DNA damage/repair balance and DNA-dependent protein kinase complex in COPD lung and in an animal model of smoking-induced lung damage and to evaluate the effects of oxidative stress on Ku expression and function in human bronchial epithelial cells. METHODS Protein expression was quantified using immunohistochemistry and/or western blotting. DNA damage/repair was measured using colorimetric assays. RESULTS 8-OH-dG, a marker of oxidant-induced DNA damage, was statistically significantly increased in the peripheral lung of smokers (with and without COPD) compared with non-smokers, while the number of apurinic/apyrimidinic (AP) sites (DNA damage and repair) was increased in smokers compared with non-smokers (p = 0.0012) and patients with COPD (p < 0.0148). Nuclear expression of Ku86, but not of DNA-PKcs, phospho-DNA-PKcs, Ku70 or γ-H2AFX, was reduced in bronchiolar epithelial cells from patients with COPD compared with normal smokers and non-smokers (p < 0.039). Loss of Ku86 expression was also observed in a smoking mouse model (p < 0.012) and prevented by antioxidants. Oxidants reduced (p < 0.0112) Ku86 expression in human bronchial epithelial cells and Ku86 knock down modified AP sites in response to oxidative stress. CONCLUSIONS Ineffective DNA repair rather than strand breakage per se accounts for the reduced AP sites observed in COPD and this is correlated with a selective decrease of the expression of Ku86 in the bronchiolar epithelium. DNA damage/repair imbalance may contribute to increased risk of lung carcinoma in COPD