Beclomethasone rapidly ablates allergen-induced beta 2-adrenoceptor pathway dysfunction in human isolated bronchi

Drug interaction and chronic obstructive respiratory disorders

Chronic obstructive respiratory disorders uncontrolled by monotherapy should be given combinations of drugs that act by distinct mechanisms of action. The rationale for combining different classes of drugs should be to elicit a synergistic interaction, lower the dose of the single components in the combinations and, thus, reduce the risk of adverse events.

The aim of this systematic review was to investigate the combined effect of drugs acting on human airways, by including studies that used a validated method for assessing the nature of drug interaction.

Current evidence indicates that drug combinations modulating the bronchial contractility induce a synergistic relaxant effect when the individual components are combined at isoeffective concentrations. There are several mechanisms of action underlying drug interactions. Pharmacological research has been directed to elucidate what causes the synergism between long-acting β₂-adrenoceptor (β₂-AR) agonists (LABAs), long-acting muscarinic antagonist (LAMAs), and inhaled corticosteroids (ICS) administered as dual or triple combination. Conversely, the mechanisms behind the additive interaction between phosphodiesterase 3 and 4 inhibitors and LAMAs, and the synergistic interaction between proliferator-activated receptor gamma ligands and β₂ agonists have been only hypothesized. Overall, the synergism elicited by combined drugs for the treatment of chronic respiratory disorders is an effect of class, rather than specific for drug combinations. Optimal synergy can be achieved only when the single agents are combined at isoeffective concentrations, and when monocomponents are given concurrently to reach together the same levels of the bronchial tree.

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Drug interaction should be identified with validated pharmacological models.

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Synergistic efficacy is the rationale for combining drugs for respiratory diseases.

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Synergy is favored when combined agents act by distinct mechanisms of action.

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Optimal synergy is achieved when drugs are combined at isoeffective concentrations.

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Synergy is a class effect and is not specific for single drug combinations.

Synergy across the drugs approved for the treatment of asthma

INTRODUCTION

Inhaled corticosteroids are the cornerstone for the treatment of stable asthma, however, when disease severity increases, escalating therapy to combinations of drugs acting on distinct signalling pathways is required. It is advantageous to providing evidence of a synergistic interaction across drug combinations, as it allows optimizing bronchodilation while lowering the dose of single agents. In the respiratory pharmacology field, two statistical models are accepted as gold standard to characterize drug interactions, namely the Bliss Independence criterion and the Unified Theory. In this review, pharmacological interactions across drugs approved for the treatment of asthma have been systematically assessed.

EVIDENCE ACQUISITION

A comprehensive literature search was performed in MEDLINE for studies that used a validated pharmacological method for assessing drug interaction. The results were extracted and reported via qualitative synthesis.

EVIDENCE SYNTHESIS

Overall, 45 studies were identified from literature search and 5 met the inclusion criteria. Current evidence coming from ex vivo models of asthma indicates that drug combinations modulating bronchial contractility induce a synergistic bronchorelaxant effect. In murine models of lung inflammation, the combination between inhaled corticosteroids and β2- adrenoceptor agonists synergistically improve lung function and the inflammatory profile.

CONCLUSIONS

There is still limited knowledge regarding the mechanistic basis underlying pharmacological interactions across drugs approved for asthma. The synergism elicited by combined agents is an effect of class. Specifically designed clinical trials are needed to confirm the results coming from preclinical evidence, but also to establish the minimal dose for combined agents to induce a synergistic interaction and maximize bronchodilation.

Racial/Ethnic-Specific Differences in the Effects of Inhaled Corticosteroid Use on Bronchodilator Response in Patients With Asthma

American Thoracic Society guidelines recommend inhaled corticosteroid (ICS) therapy, plus a short-acting bronchodilator, in patients with persistent asthma. However, few prior studies have examined the efficacy of this combination in children of all racial/ethnic groups. We evaluated the association between ICS use and bronchodilator response (BDR) in three pediatric populations with persistent asthma (656 African American, 916 Puerto Rican, and 398 Mexican American children). The association was assessed using multivariable quantile regression. After adjusting for baseline forced expiratory volume in one second and use of controller medications, ICS use was significantly associated with increased BDR only among Mexican Americans (1.56%, P = 0.028) but not African Americans (0.49%, P = 0.426) or Puerto Ricans (0.16%, P = 0.813). Our results demonstrate that ICS augmentation is disproportionate across racial/ethnic groups, where improved BDR is observed in Mexican Americans only. This study highlights the complexities of treating asthma in children, and reinforces the importance of investigating the influence of race/ethnicity on pharmacological response.

Interaction between corticosteroids and muscarinic antagonists in human airways

BACKGROUND

To date there is emerging clinical evidence to add long-acting anti-muscarinic agents (LAMAs) with inhaled corticosteroid (ICSs) in asthma, but the pharmacological rationale that supports the use of such a combination has not yet been explained. The aim of this study was to pharmacologically investigate the interaction between the ICS beclomethasone and the LAMA glycopyrronium on the human airway smooth muscle (ASM) tone.

METHODS

We investigated the rapid non-genomic bronchorelaxant effect of beclomethasone and glycopyrronium, administered alone and in combination, in human isolated bronchi and bronchioles. Experiments were carried out also in passively sensitized airways and the pharmacological analysis of drug interaction was performed by Bliss Independence method.

RESULTS

The acute administration of beclomethasone and glycopyrronium induced a significant relaxation of passively sensitized ASM pre-contracted with histamine, by causing submaximal/maximal inhibition of the contractile tone in both medium bronchi and bronchioles. Beclomethasone was characterized by a rapid non-genomic and epithelium independent bronchorelaxant effect. In passively sensitized airways, this effect seemed to be dependent by the activation of a Gsα--cyclic adenosine monophosphate (cAMP)--protein kinase A cascade. While no synergistic interaction was detected in non-sensitized bronchi, the beclomethasone/glycopyrronium combination synergistically enhanced the relaxation of passively sensitized medium and small bronchi. The synergistic interaction between beclomethasone and glycopyrronium was associated with an increase of cAMP concentrations.

CONCLUSIONS

Our study provides for the first time the pharmacological rationale for combining low doses of an ICS plus a LAMA.

Alternate glucocorticoid receptor ligand binding structures influence outcomes in an in vivo tissue regeneration model

Since their characterization, glucocorticoids (GCs), the most commonly prescribed immunomodulatory drugs, have undergone numerous structural modifications designed to enhance their activity. In vivo assessment of these corticosteroid analogs is essential to understand the difference in molecular signaling of the ligands that share the corticosteroid backbone. Our research identified a novel function of GCs as modulators of tissue regeneration and demonstrated that GCs activate the glucocorticoid receptor (GR) to inhibit early stages of tissue regeneration in zebrafish (Danio rerio). We utilized this phenomenon to assess the effect of different GC analogs on tissue regeneration and identified that some GCs such as beclomethasone dipropionate (BDP) possess inhibitory properties, while others, such as dexamethasone and hydrocortisone have no effect on regeneration. We performed in silico molecular docking and dynamic studies and demonstrated that type and size of substitution at the C17 position of the cortisol backbone confer a unique stable conformation to GR on ligand binding that is critical for inhibitory activity. In the field of tissue regeneration, our study is one of the first Structure Activity Relationship (SAR) investigations performed in vertebrates demonstrating that the in vivo tissue regeneration model is a powerful tool to probe structure function relationships, to understand regenerative biology, and to assist in rational drug design.

Beta-Adrenergic Agonists

Inhaled β₂-adrenoceptor (β₂-AR) agonists are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptoms-relievers and, in combination with inhaled corticosteroids, as disease-controllers. In this article, we first review the basic mechanisms by which the β₂-adrenergic system contributes to the control of airway smooth muscle tone. Then, we go on describing the structural characteristics of β₂-AR and the molecular basis of G-protein-coupled receptor signaling and mechanisms of its desensitization/ dysfunction. In particular, phosphorylation mediated by protein kinase A and β-adrenergic receptor kinase are examined in detail. Finally, we discuss the pivotal role of inhaled β₂-AR agonists in the treatment of asthma and the concerns about their safety that have been recently raised.

Airway smooth muscle as a model for new investigative drugs in asthma

Bronchial asthma as such exists because airway smooth muscle (ASM) contracts excessively in response to various stimuli. After several decades during which research was mainly focused on airway inflammation, increasing attention is now being paid to a possible abnormal behaviour of ASM. Thus, ASM is regarded as a major target for anti-asthma treatments. This review first describes the mechanisms of ASM contraction and airway hyperresponsiveness, through cellular, animal and human models. The developments of new drugs targeting extra and/or intracellular pathway of ASM contraction are discussed.

Glucocorticoids Alter the Balance Between Pro- and Anti-inflammatory Mediators in the Myocardium in a Porcine Model of Brain Death

BACKGROUND

Cardiac dysfunction after brain death (BD) limits donors for cardiac transplantation. Glucocorticoids ameliorate brain death-induced donor heart dysfunction. We hypothesized that glucocorticoid therapy alleviates myocardial depression through altering the balance between pro- and anti-inflammatory mediators via the nuclear factor-kappaB (NF-kappaB)/inhibitor of kappaB-alpha (IkappaBalpha) pathway and/or by preserving beta-adrenergic receptor (betaAR) signaling in the heart.

METHODS

Crossbred pigs (25 to 35 kg) were randomly assigned to the following groups (n = 5/treatment): sham (Group 1); BD (Group 2); and BD with glucocorticoids (30 mg/kg methylprednisolone), either 2 hours before (Group 3) or 1 hour after BD (Group 4). Tumor necrosis factor-alpha (TNF-alpha) levels were measured in plasma at baseline and 1 hour and 6 hours after BD. Protein levels were measured in left ventricular homogenates procured 6 hours after BD.

RESULTS

Pro-inflammatory proteins (TNF-alpha) and interleukin-6 were lower in Group 3 and Group 4 compared with Group 2 at 6 hours after BD (p < 0.01). Intracellular adhesion molecule-1 was also lower in Group 4 compared with Group 2 (p = 0.001). Interleukin-10, an anti-inflammatory mediator, was lower in Group 4 than in Group 2 (p < 0.001), but not different between Groups 2 and 3. At 6 hours after BD, neither NF-kappaB activity nor basal adenylate cyclase activity differed between Groups 3 and 4 compared with Group 2.

CONCLUSIONS

Glucocorticoids maintained myocardial function and shifted the balance of pro- and anti-inflammatory mediators after BD. The mechanisms by which glucocorticoids preserve myocardial function, however, do not appear to involve the NF-kappaB pathway or betaAR signaling.

Cysteinyl-leukotrienes in the regulation of beta2-adrenoceptor function: an in vitro model of asthma

Background

The response to β₂-adrenoceptor agonists is reduced in asthmatic airways. This desensitization may be in part due to inflammatory mediators and may involve cysteinyl-leukotrienes (cysteinyl-LTs). Cysteinyl-LTs are pivotal inflammatory mediators that play important roles in the pathophysiology of asthma, allergic rhinitis, and other inflammatory conditions. We tested the hypothesis that leukotriene D₄ (LTD₄) and allergen challenge cause β₂-adrenoceptor desensitization through the activation of protein kinase C (PKC).

Methods

The isoproterenol-induced cAMP accumulation was evaluated in human airway smooth muscle cell cultures challenged with exogenous LTD₄ or the PKC activator phorbol-12-myristate-13-acetate with or without pretreatments with the PKC inhibitor GF109203X or the CysLT₁R antagonist montelukast. The relaxant response to salbutamol was studied in passively sensitized human bronchial rings challenged with allergen in physiological salt solution (PSS) alone, or in the presence of either montelukast or GF109203X.

Results

In cell cultures, both LTD₄ and phorbol-12-myristate-13-acetate caused significant reductions of maximal isoproterenol-induced cAMP accumulation, which were fully prevented by montelukast and GF109203X, respectively. More importantly, GF109203X also prevented the attenuating effect of LTD₄ on isoproterenol-induced cAMP accumulation. In bronchial rings, both montelukast and GF109203X prevented the rightward displacement of the concentration-response curves to salbutamol induced by allergen challenge.

Conclusion

LTD₄ induces β₂-adrenoceptor desensitization in human airway smooth muscle cells, which is mediated through the activation of PKC. Allergen exposure of sensitized human bronchi may also cause a β₂-adrenoceptor desensitization through the involvement of the CysLT₁R-PKC pathway.

Single inhaler budesonide/formoterol in exacerbations of chronic obstructive pulmonary disease

Inhaled bronchodilators, particularly short-acting inhaled beta(2)-agonists, and systemic glucocorticosteroids are effective treatments for acute exacerbations of chronic obstructive pulmonary disease (COPD). However, in the treatment of these episodes there may be some advantages to the longer-acting agents in that there will be prolonged bronchodilation. Moreover, high doses of systemic glucocorticosteroids are associated with a significant risk of side effects. In the last few years, evidence is mounting that nebulized budesonide and inhaled formoterol might be an alternative to oral prednisolone and short-acting beta(2)-agonists, respectively, in the treatment of acute exacerbations of COPD. Interestingly, some new data suggest that a combination therapy with single inhaler containing budesonide and formoterol may be an alternative to traditional therapy in the treatment of acute exacerbations of this disorder. However, since individual studies are typically statistically underpowered and are remarkably heterogeneous with regard to their conclusions, larger studies are needed to confirm these preliminary findings and determine conclusively any impact of budesonide/formoterol combination in acutely ill COPD patients.

Onset of action of formoterol/budesonide in single inhaler vs. formoterol in patients with COPD

Formoterol is a beta(2)-agonist bronchodilator that combines a fast onset of action with a long duration of broncholytic effect. An increasing documentation is showing that the combination of a long acting beta(2)-adrenoceptor agonist bronchodilator and an inhaled corticosteroid targets the airways obstruction in patients with COPD. In this study, we have explored whether the acute addition of an inhaled corticosteroid influences the fast bronchodilator response to formoterol. A total of 20 patients with stable COPD were randomized. Single doses of formoterol/budesonide 2 x (4.5/160)microg or formoterol 2 x 4.5 microg were given via Turbuhaler. Serial measurements of FEV(1) were performed over 60 min. Formoterol/budesonide elicited a significantly larger mean FEV(1)-AUC(0-15 min) than formoterol alone. Also the change in FEV(1) 15 min after inhalation of formoterol/budesonide combination (0.197 l; 95% CI: to 0.142-0.252) was greater than that induced by formoterol alone (0.147 l; 95% CI: to 0.092-0.201). The mean increases in FEV(1) were always higher after budesonide/formoterol than formoterol alone, although both treatments induced a significant improvement over baseline at each explored time point. Even the FEV(1)-AUC(0-60 min) after formoterol/budesonide was significantly larger than that after formoterol. Both treatments induced a significant reduction in VAS score but did not modify heart rate in a statistically significant manner. This study indicates that the addition of budesonide influences the fast onset of action of formoterol, but does not induce systemic effects, in patients with stable COPD.