Albuterol does not antagonize the inhibitory effect of dexamethasone on monocyte cytokine release

Effect of procaterol on Th2-related chemokines production in human monocyte and bronchial epithelial cells

Procaterol is a β2-adrenoceptor agonist used as a bronchodilator for the treatment of asthma; it also possesses an anti-inflammatory property. As chemokines play a pivotal role in inflammation and the pathogenesis of asthma, we investigated the effects of procaterol on type 2 helper T cell (Th2)-related [macrophage-derived chemokine (MDC) and I-309] and type 1 helper T cell (Th1)-related chemokines [monokine-induced by IFN-gamma (Mig) and interferon-inducible protein 10 (IP-10)] production of THP-1 cells and human primary monocytes. The effect on thymus- and activation-regulated chemokine (TARC) production in BEAS-2B cells was also evaluated. Nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) inhibitors were used to ascertain the intracellular signal pathways involved, and etazolate, a phosphodiesterase 4 inhibitor, was used to assess the correlation between the β2-adrenoceptor-cAMP pathway and the effect on chemokines. In addition, chromatin immunoprecipitation assays (ChIPs) were performed to detect histone modification in the TARC promoter region. MDC and I-309 production of both THP-1 cells and primary human monocytes, as well as TARC expression of BEAS-2B cells, were significantly inhibited by procaterol (10(-10)-10(-7) M); however, procaterol did not suppress Mig and IP-10 expression by THP-1 cells. MDC secreted by monocytes is associated with the NF-κB and MAPK signaling pathways, in particular p38- and c-Jun N-terminal kinase (JNK) MAPKs. Etazolate blocked the expression of MDC by THP-1 cells and TARC by BEAS-2B cells. ChIP assay revealed decreased trimethylation of lysine 4 in histone 3 (H3K4) in the TARC promoter region of BEAS-2B cells. In conclusion, procaterol could inhibit Th2-related chemokines production in human monocytes and bronchial epithelial cells, an effect that may be mediated through not only the NF-κB, p38, and JNK-MAPK pathways, but also the β2-adrenoceptor-cAMP pathway. Most importantly, the suppressive effect of Th2-related chemokines production by procaterol might be regulated via post-transcriptional modification by decreasing H3K4 trimethylation.

An estimation of beta 2-adrenoceptor reserve on human bronchial smooth muscle for some sympathomimetic bronchodilators

BACKGROUND AND PURPOSE

The beta(2)-adrenoceptor on human pro-inflammatory cells is exquisitely sensitive to desensitization, whereas beta(2)-adrenoceptor-mediated relaxation of human airways smooth muscle (HASM) is relatively resistant to this phenomenon. An explanation for this discrepancy is that a large beta(2)-adrenoceptor 'reserve' exists on HASM cells for sympathomimetic bronchodilators, which protects against desensitization.

EXPERIMENTAL APPROACH

The operational model of agonism was used to estimate the affinity of salbutamol, terbutaline, formoterol and procaterol for the beta(2)-adrenoceptors in methacholine (MCh)-contracted HASM from which the relationship between fractional receptor occupancy and relaxation was determined. This analysis was performed under conditions of fractional, irreversible, beta(2)-adrenoceptor inactivation and, for salbutamol and terbutaline only, by the comparative method of Barlow et al. The affinity of salbutamol for the beta(2)-adrenoceptor guinea-pig eosinophils and the receptor/occupancy-response relationship for the suppression of the respiratory burst (an index of pro-inflammatory cell function) was also determined.

KEY RESULTS

For salbutamol and terbutaline, both pharmacological approaches yielded in HASM discrepant affinity estimates (values differed, maximally, by 0.67 log(10) unit). However, affinity values more closely agreed (difference <0.47 log(10) unit), when operational analysis was performed on data corrected for 'fade' of the MCh-induced contraction. Plots of fractional beta(2)-adrenoceptor occupancy versus relaxation indicated a receptor 'reserve' for all agonists tested at all levels of response. In contrast, minimal receptor reserve was detected for the ability of salbutamol to suppress respiratory burst activity in eosinophils.

CONCLUSIONS AND IMPLICATIONS

These data may help explain the relative inability of sympathomimetic bronchodilators to render HASM tolerant to beta(2)-adrenoceptor-mediated relaxation.

Cellular endotoxin desensitization in patients with severe chronic heart failure

BACKGROUND

Increased levels of bacterial lipopolysaccharide (LPS) have been demonstrated in chronic heart failure (CHF). LPS can induce cellular desensitization, with specific down-regulation of LPS-mediated cellular tumor necrosis factor (TNF-alpha) production which does not affect other cytokine parameters. It is not known if LPS desensitization occurs in CHF.

METHODS AND RESULTS

Mononuclear cells from 24 CHF patients (mean age 70+/-2 years, age range 58 to 78 years, NYHA class 3.0+/-0.2) and 11 healthy controls (mean age 53+/-3 years, age range 39 to 75 years) were separated from venous blood and cultured for 24 h with LPS (E. coli, 0-10 ng/mL). Culture supernatants were tested for TNF-alpha and interleukin-1 receptor antagonist (IL-1RA). Patients were subgrouped into mild (n=10), moderate (n=5), and severe (n=9) CHF. Independently of age, mononuclear cells from patients with severe heart failure produced less TNF-alpha than controls (p<0.05) and patients with mild (p<0.001) or moderate CHF (p<0.05). IL-1RA release was higher for CHF patients as a group, compared with controls (p<0.05). There was no significant difference in IL-1RA release between CHF patient subgroups.

CONCLUSIONS

Mononuclear cells from patients with severe heart failure produce significantly less TNF-alpha than healthy controls or patients with mild to moderate disease. Production of IL-1RA is not affected. This resembles a picture indicative of LPS desensitization occurring in patients with severe CHF.

Impaired inhibition by dexamethasone of cytokine release by alveolar macrophages from patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by inflammation of the respiratory tract in which macrophages are the predominant inflammatory cell and for which the efficacy of treatment with corticosteroids is controversial. We investigated the effect of dexamethasone on basal and interleukin (IL)-1beta or cigarette smoke media (CSM)-stimulated release of IL-8 and granulocyte macrophage-colony stimulating factor (GM-CSF) by bronchoalveolar lavage macrophages from cigarette smokers and patients with COPD (n = 15). Basal release of IL-8 was approximately fivefold greater in patients with COPD than smokers, whereas GM-CSF was similar for each group. IL-1beta and CSM increased IL-8 and GM-CSF release by macrophages from both smokers and patients with COPD. Dexamethasone did not inhibit basal or stimulated IL-8 release from macrophages from patients with COPD but inhibited release in smokers. In contrast, basal and IL-1beta-stimulated GM-CSF release, but not CSM-stimulated release, was inhibited by dexamethasone. We conclude that the lack of efficacy of corticosteroids in COPD might be due to the relative steroid insensitivity of macrophages in the respiratory tract.

Additive anti-inflammatory effect of formoterol and budesonide on human lung fibroblasts

BACKGROUND

It has been shown that treatment with a long acting beta2 agonist in addition to a glucocorticoid is beneficial in the treatment of asthma. In asthma inflammatory cells, particularly eosinophils, migrate into the pulmonary tissue and airway lumen by means of adhesion molecules expressed on resident tissue cells--that is, fibroblasts--and become activated by cytokines and adhesive interactions. A study was undertaken to determine whether an interaction exists between the long acting beta2 agonist formoterol and the glucocorticoid budesonide on inhibition of adhesion molecule expression, as well as chemo/cytokine production by human lung fibroblasts.

METHODS

Lung fibroblasts were preincubated with therapeutically relevant drug concentrations of 10(-8) M to 10(-10) M. Cells were stimulated with interleukin (IL)-1beta (1 or 10 U/ml) for 8 hours and supernatants were collected for measurement of GM-CSF and IL-8 concentrations. The cells were fixed and subjected to a cell surface ELISA technique to measure the expression of ICAM-1 and VCAM-1.

RESULTS

Formoterol exerted an additive effect on the inhibition of IL-1beta stimulated ICAM-1 and VCAM-1 upregulation and GM-CSF production by budesonide in concentrations of 10(-9) M and above (p<0.05). IL-8 production was not influenced by formoterol.

CONCLUSION

Formoterol exerts an additive effect on the anti-inflammatory properties of budesonide. In vitro data support the finding that the combination of budesonide and formoterol in asthma treatment strengthens the beneficial effect of either drug alone.

Suppression of granulocyte/macrophage colony-stimulating factor release from human monocytes by cyclic AMP-elevating drugs: role of interleukin-10

1. Granulocyte/macrophage colony-stimulating factor (GM-CSF) is a pro-inflammatory cytokine secreted by cells of the monocyte/macrophage lineage and has been implicated in the pathogenesis of bronchitis and asthma. 2. In the present study we have evaluated the effect of several cyclic AMP-elevating agents on lipopolysaccharide (LPS)-induced GM-CSF release from human monocytes and the extent to which the anti-inflammatory cytokine, interleukin (IL)-10, is involved. 3. LPS evoked a concentration-dependent generation of GM-CSF from human monocytes that was inhibited, at the mRNA and protein level, by 8-Br-cyclic AMP, cholera toxin, prostaglandin E2 (PGE2) and a number of structurally dissimilar phosphodiesterase (PDE) 4 inhibitors. 4. Pre-treatment of monocytes with a concentration of an anti-IL-10 monoclonal antibody that abolished the inhibitory action of a maximally effective concentration of exogenous human recombinant IL-10, significantly augmented LPS-induced GM-CSF generation. This effect was associated with a parallel upwards displacement of the concentration-response curves that described the inhibition of GM-CSF by PGE2, 8-Br-cyclic AMP and the PDE4 inhibitor, rolipram, without significantly changing the potency of any drug. Consequently, the maximum percentage inhibition of GM-CSF release was reduced. Further experiments established that the reduction in the maximum inhibition of GM-CSF release seen in anti-IL-10-treated cells was not due to functional antagonism as rolipram, PGE2 and 8-Br-cyclic AMP were equi-effective at all concentrations of LPS studied. 5. These data indicate that cyclic AMP-elevating drugs attenuate the elaboration of GM-CSF from LPS-stimulated human monocytes by a mechanism that is not mediated via IL-10. Suppression of GM-CSF from monocytes may explain, at least in part, the efficacy of PDE4 inhibitors in clinical trials of chronic obstructive pulmonary disease.

Expression of GATA family of transcription factors in T-cells, monocytes and bronchial biopsies

GATA-binding proteins are a subfamily of zinc finger transcription factors with six members (GATA-1-6) that interact with the GATA deoxyribonucleic acid (DNA) sequence. This sequence is found in the regulatory regions of many genes including those encoding T-helper 2 (Th2)-like cytokines, receptors, adhesion molecules and enzymes, which may be important in the pathogenesis of bronchial asthma. The expression of GATA-3, 4 and -6 was investigated in peripheral blood T-lymphocytes and monocytes and bronchial biopsies from 11 normal subjects and 10 steroid-naive asthmatic patients. Using Western blot analysis, T-cells from asthmatic subjects expressed 5 times the level of GATA-3 compared to that in normals. Confocal microscopy indicated that GATA-3 expression was both nuclear and cytoplasmic. GATA DNA binding complex containing GATA-3 was elevated in Th2 cells as determined by electrophorectic mobility shift assay. In contrast, monocytes from normal and asthmatic subjects expressed GATA-4 and -6 in equal amounts, but no GATA-3 was found. Using immunohistochemistry in bronchial biopsies, epithelial cells expressed high levels of GATA-3, GATA-4 and GATA-6 proteins. Comparison of Western blots of bronchial biopsies showed no significant differences between normal and asthmatic subjects. In conclusion, the increased expression of GATA-3 in asthmatic T-cells may underlie augmented T-helper 2-like cytokines in this disease. However, the unaltered GATA-3 expression in epithelial cells suggests a distinct role for GATA-3 in these cells unrelated to T-helper 2-like cytokine release. Finally, no evidence was found for an increased expression of GATA-4 and GATA-6 in asthma.

Effects of formoterol and budesonide on GM-CSF and IL-8 secretion by triggered human bronchial epithelial cells

The effect of formoterol, alone and in combination with budesonide, upon tumour necrosis factor-alpha stimulated (10 ng x mL(-1)) human bronchial epithelial cells was investigated. Addition of formoterol (> or = 10(-10) M) reduced granulocyte macrophage-colony stimulating factor (GM-CSF) levels, as assessed by enzyme-linked immunosorbent assay, by 40-50% and increased interleukin (IL)-8 levels by approximately 50%. The effects of formoterol were long lasting (23 h). Budesonide (10(-8) M) reduced the amounts of both cytokines (GM-CSF and IL-8) by 40%. Simultaneous addition of formoterol and budesonide reduced GM-CSF levels approximately 75%, while IL-8 levels were decreased approximately 40%, similar to the reduction obtained with budesonide alone. The glucocorticoid receptor (GR) antagonist RU486 did not influence the effect of formoterol, suggesting no involvement of the GR. Formoterol rapidly induced an elevation in intracellular cyclic adenosine monophosphate, which was reduced in the presence of propranolol. In addition, the alterations in cytokine secretion induced by formoterol could be fully blocked by propranolol, demonstrating that these effects are beta2-receptor mediated. In conclusion, the combination of budesonide and formoterol reduces the secretion of granulocyte macrophage-colony stimulating factor to basal levels and counteracts the capacity of formoterol alone to induce interleukin-8 production, modulations which may facilitate improved asthma control.

p38 MAP kinase and MKK-1 co-operate in the generation of GM-CSF from LPS-stimulated human monocytes by an NF-kappa B-independent mechanism

1. The extent to which the p38 mitogen-activated protein (MAP) kinase and MAP kinase kinase (MKK)-1-signalling pathways regulate the expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) from LPS-stimulated human monocytes has been investigated and compared to the well studied cytokine tumour necrosis factor-alpha (TNF alpha). 2. Lipopolysaccharide (LPS) evoked a concentration-dependent generation of GM-CSF from human monocytes. Temporally, this effect was preceded by an increase in GM-CSF mRNA transcripts and abolished by actinomycin D and cycloheximide. 3. LPS-induced GM-CSF release and mRNA expression were associated with a rapid and time-dependent activation of p38 MAP kinase, ERK-1 and ERK-2. 4. The respective MKK-1 and p38 MAP kinase inhibitors, PD 098059 and SB 203580, maximally suppressed LPS-induced GM-CSF generation by >90%, indicating that both of these signalling cascades co-operate in the generation of this cytokine. 5. Electrophoretic mobility shift assays demonstrated that LPS increased nuclear factor kappa B (NF-kappa B) : DNA binding. SN50, an inhibitor of NF-kappa B translocation, abolished LPS-induced NF-kappaB : DNA binding and the elaboration of TNFalpha, a cytokine known to be regulated by NF-kappaB in monocytes. In contrast, SN50 failed to affect the release of GM-CSF from the same monocyte cultures. 6. Collectively, these results suggest that the generation of GM-CSF by LPS-stimulated human monocytes is regulated in a co-operative fashion by p38 MAP kinase- and MKK-1-dependent signalling pathways independently of the activation of NF-kappa B.

Effects of long-term oxygen therapy in patients with chronic obstructive pulmonary disease

Long-term oxygen therapy is largely used in the management of severe hypoxemia in patients with chronic obstructive pulmonary disease. It was demonstrated that long-term oxygen therapy prolongs life, prevents progression of hypoxic pulmonary hypertension, and controls polycythemia. Recent data suggest that in patients with moderate hypoxemia (Pao2 > 55 mm Hg), long-term oxygen therapy does not prolong life. Life expectancy in those patients seems to depend on the severity of airway obstruction. Long-term oxygen therapy improves cognitive functions and emotional status. There is some evidence suggesting that it also improves quality of life, but more data are needed. There are conflicting data concerning the rationale for nocturnal oxygen supplementation in patients with arterial blood desaturation during sleep.