Interactions between corticosteroids and beta-adrenergic agonists in asthma disease induction, progression, and exacerbation

Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis

β2-Agonists (β2-adrenergic agonists, bronchodilatants, and sympathomimetic drugs) are a group of drugs that are mainly used in asthma and obstructive pulmonary diseases. In practice, the substances used to contain one or more stereogenic centers in their structure and their enantiomers exhibit different pharmacological properties. In terms of bronchodilatory activity, (R)-enantiomers showed higher activity. The investigation of stereoselectivity in action and disposition of chiral drugs together with the preparation of pure enantiomer drugs calls for efficient stereoselective analytical methods. The overview focuses on the stereoselectivity in pharmacodynamics and pharmacokinetics of β2-agonists and summarizes the stereoselective analytical methods for the enantioseparation of racemic beta-agonists (HPLC, LC-MS, GC, TLC, CE). Some methods of the stereoselective synthesis for β2-agonists preparation are also presented.

Repeated exacerbation of asthma: An intrinsic phenotype of uncontrolled asthma

Asthma is a chronic disease of the airways affecting a large number of people across the globe. Uncontrolled asthma poses an emotional as well as the physical burden on patients and results in a great economic burden. “Exacerbation-prone phenotype” asthmatics are a cluster of patients who may suffer from more frequent and severe exacerbations than other asthmatics. Factors such as inadequate symptom control, improper adherence to medications, and incorrect use of inhalers are responsible for frequent asthma exacerbations. Caring for the patient with “exacerbation-prone asthma” needs participation from both the doctor as well as the patient. Self-management, improving knowledge about the disease, control of comorbidities, and a stepwise approach with the use of a single inhaler maintenance and reliever therapy in patients with severe asthma could help in delivering better care for the “exacerbation-prone phenotype” of asthmatics.

Repeated Stress Exaggerates Lipopolysaccharide-Induced Inflammatory Response in the Rat Spleen

Spleen is an immune organ innervated with sympathetic nerves which together with adrenomedullary system control splenic immune functions. However, the mechanism by which prior stress exposure modulates the immune response induced by immunogenic challenge is not sufficiently clarified. Thus, the aim of this study was to investigate the effect of a single (2 h) and repeated (2 h daily for 7 days) immobilization stress (IMO) on the innate immune response in the spleen induced by lipopolysaccharide (LPS, 100 µg/kg). LPS elevated splenic levels of norepinephrine and epinephrine, while prior IMO prevented this response. LPS did not alter de novo production of catecholamines, however, prior IMO attenuated phenylethanolamine N-methyltransferase gene expression. Particularly repeated IMO exacerbated LPS-induced down-regulation of α1B- and β1-adrenergic receptors (ARs), while enhanced α2A- and β2-AR mRNAs. Elevated expression of inflammatory mediators (iNOS2, IL-1β, IL-6, TNF-α, IL-10) was observed following LPS and repeated IMO again potentiated this effect. These changes were associated with enhanced Ly6C gene expression, a monocyte marker, and elevated MCP-1, GM-CSF, and CXCL1 mRNAs suggesting an increased recruitment of monocytes and neutrophils into the spleen. Additionally, we observed increased Bax/Bcl-1 mRNA ratio together with reduced B cell numbers in rats exposed to repeated IMO and treated with LPS but not in acutely stressed rats. Altogether, these data indicate that repeated stress via changes in CA levels and specific α- and β-AR subtypes exaggerates the inflammatory response likely by recruiting peripheral monocytes and neutrophils to the spleen, resulting in the induction of apoptosis within this tissue, particularly in B cells. These changes may alter the splenic immune functions with potentially pathological consequences.

A critical role for IRF5 in regulating allergic airway inflammation

Interferon regulatory factor 5 (IRF5) is a key transcription factor involved in the control of the expression of proinflammatory cytokine and responses to infection, but its role in regulating pulmonary immune responses to allergen is unknown. We used genetic ablation, adenoviral vector-driven overexpression, and adoptive transfer approaches to interrogate the role of IRF5 in pulmonary immunity and during challenge with the aeroallergen, house dust mite. Global IRF5 deficiency resulted in impaired lung function and extracellular matrix (ECM) deposition. IRF5 was also essential for effective responses to inhaled allergen, controlling airway hyperresponsiveness, mucus secretion, and eosinophilic inflammation. Adoptive transfer of IRF5-deficient alveolar macrophages into the wild-type pulmonary milieu was sufficient to drive airway hyperreactivity, at baseline or following antigen challenge. These data identify IRF5-expressing macrophages as a key component of the immune defense of the airways. Manipulation of IRF5 activity in the lung could therefore be a viable strategy for the redirection of pulmonary immune responses and, thus, the treatment of lung disorders.

Effect of fluticasone and salmeterol on tracheal responsiveness to ovalbumin and lung inflammation, administrated during and after sensitization

The effect of duration of administration of fluticasone propionate and salmeterol on tracheal responsiveness to ovalbumin and total and differential white blood cell in sensitized guinea pig was examined. Six groups of guinea pigs (n = 7) were sensitized to ovalbumin. Three groups of them were subjected to inhaled fluticasone propionate and salmeterol, one group during sensitization (A), one group after that (for 18 days, B), and the other one during sensitization but with 18 days delay before measurements (C). Three other groups were treated with placebo in the same manner. The tracheal responsiveness to ovalbumin and total and differential white blood cells of three placebo groups were significantly higher than those of control group (P < 0.001 for all cases). Tracheal responsiveness to ovalbumin and total and differential white blood cell in treated groups with fluticasone propionate and salmeterol were significantly decreased compared to those of placebo groups (nonsignificant to P < 0.001). The improvement in all variables in treatment groups A and C were more pronounced than group B. The results showed that fluticasone propionate and salmeterol had a prevention effect on tracheal hyperresponsiveness to ovalbumin and lung inflammation which was more pronounced when administered during than after sensitization.

Histological effects of inhaled corticosteroids and ß2-agonists on laryngeal mucosa in an allergic rat model

OBJECTIVE

To constitute an animal model of laryngeal allergy and evaluate the laryngeal effects of inhaled corticosteroids and ß2-agonists on the laryngeal mucosa in an allergic rat model.

STUDY DESIGN

Prospective randomized.

SETTING

The Experimental Medical Research Institute (DETAE) at Istanbul University.

SUBJECTS AND METHODS

Wistar Albino rats (n = 32) were sensitized with ovalbumin. Unsensitized rats (n = 8) served as controls. The rats were exposed to aerosolized ovalbumin (1%). On days 28 through 42, every 2 days preceeding ovalbumin exposure, rats were further exposed to aerosolized phosphate buffered saline (n = 8), fluticasone propionate (n = 8), salbutamol (n = 8), and combined salbutamol+fluticasone propionate (n = 8). Inflammatory cell infiltration was graded semi-quantitatively. The quantitative data included mast cell count and degranulation. Ultrathin sections were investigated under transmission electron microscope.

RESULTS

The simultaneous and pairwise comparison of groups (Kruskal-Wallis) revealed statistically significant difference among groups at supraglottic level (critical P < .05, <.01) and no difference at glottic level. In ovalbumin+phosphate buffered saline exposed rats, the light microscopy of supraglottic mucosa revealed regular epithelium with severe inflammatory cell infiltration and increased mast cell count. Electron microscopy revealed increased mast cell degranulation. Increased inflammatory cell infiltration was detected along with reduced mast cell count among fluticasone propionate treated rats. Mild inflammatory cell infiltration was encountered in combined salbutamol+fluticasone propionate treated rats.

CONCLUSION

This study supported the presence of localized allergic reaction in the supraglottic laryngeal mucosa through the observation of increased mast cell number and degranulation. It was also shown that inhaled corticosteroids increase inflammation whereas combined inhaled corticosteroids and ß2-agonists minimize allergic and inflammatory reactions in supraglottic laryngeal mucosa providing a safer therapeutic option.

Effects of budesonide/formoterol combination therapy versus budesonide alone on airway dimensions in asthma

BACKGROUND AND OBJECTIVE

Combination therapy with inhaled corticosteroids and long-acting β(2)-agonists results in improved asthma symptom control compared with the use of inhaled corticosteroids alone. However, the effects of combination therapy on structural changes and inflammation of the airways are still unknown. The aim of this study was to compare the effects of budesonide/formoterol with those of budesonide alone on airway dimensions and inflammation in individuals with asthma.

METHODS

Fifty asthmatic patients were randomized to treatment with budesonide/formoterol (200/6 µg, two inhalations bd) or budesonide (200 µg, two inhalations bd) for 24 weeks. Airway dimensions were assessed using a validated computed tomography technique, and airway wall area (WA) corrected for body surface area (BSA), percentage WA (WA%), wall thickness/Ösquare root BSA, and luminal area (Ai)/BSA at the right apical segmental bronchus, were measured. The percentage of eosinophils in induced sputum, pulmonary function, and Asthma Quality of Life Questionnaires (AQLQ) were also evaluated.

RESULTS

There were significantly greater decreases in WA/BSA (P < 0.05), WA% (P < 0.001) and wall thickness/square root BSA (P < 0.05), and increases in Ai/BSA (P < 0.05), in subjects treated with budesonide/formoterol compared with those treated with budesonide. The reduction in sputum eosinophils and increase in per cent of predicted forced expiratory volume in 1 s (FEV(1) %) were greater for subjects treated with budesonide/formoterol compared with those treated with budesonide alone. In the budesonide/formoterol group, the changes in WA% were significantly correlated with changes in sputum eosinophils and FEV(1%) (r = 0.84 and r = 0.64, respectively). There were improvements in the AQLQ scores after treatment with budesonide/formoterol.

CONCLUSIONS

Budesonide/formoterol combination therapy is more effective than budesonide alone for reducing airway wall thickness and inflammation in individuals with asthma.

The effect of budesonide/formoterol maintenance and reliever therapy on the risk of severe asthma exacerbations following episodes of high reliever use: an exploratory analysis of two randomised, controlled studies with comparisons to standard therapy

BACKGROUND

Divergent strategies have emerged for the management of severe asthma. One strategy utilises high and fixed doses of maintenance treatment, usually inhaled corticosteroid/long-acting β2-agonist (ICS/LABA), supplemented by a short-acting β2-agonist (SABA) as needed. Alternatively, budesonide/formoterol is used as both maintenance and reliever therapy. The latter is superior to fixed-dose treatment in reducing severe exacerbations while achieving similar or better asthma control in other regards. Exacerbations may be reduced by the use of budesonide/formoterol as reliever medication during periods of unstable asthma. We examined the risk of a severe exacerbation in the period after a single day with high reliever use.

METHODS

Episodes of high reliever use were quantified and exacerbations occurring post-index day with these episodes were examined post hoc in two double-blind studies comparing the efficacy and safety of budesonide/formoterol maintenance and reliever therapy (Symbicort SMART™, Turbuhaler®) 160/4.5 μg twice daily plus as needed with similar or higher maintenance doses of ICS/LABA plus SABA or formoterol.

RESULTS

Budesonide/formoterol maintenance and reliever therapy significantly reduced the risk of episodes of high reliever use (>6 inhalations/day) vs. all alternative ICS/LABA regimens. With conventional fixed-dose treatment the need for exacerbation treatment within 21 days ranged from 6.0-10.1% of days post-index for all regimens compared with 2.5-3.4% of days with budesonide/formoterol maintenance and reliever therapy.

CONCLUSIONS

Budesonide/formoterol maintenance and reliever therapy reduces the incidence of high reliever episodes and the exacerbation burden immediately following these episodes vs. alternative ICS/LABA plus SABA regimens at up to double the maintenance dose of ICS.

TRIAL REGISTRATION

These studies do not have registration numbers as they were conducted before clinical trial registration was required.

The CHI3L1 rs4950928 polymorphism is associated with asthma-related hospital admissions in children and young adults

BACKGROUND

Asthma exacerbations are the commonest cause of medical admissions in childhood. These have a significant effect on quality of life and are a major financial burden on worldwide healthcare services. A range of gene-environment interactions may influence the course and severity of asthma in children and their response to medication. The Chitinase 3-like 1 (CHI3L1)-131C>G genotype (rs4950928) is associated with increased asthma susceptibility and severity in adults.

OBJECTIVES

To study the interactions of the Chitinase 3-Like-1 functional promoter SNP rs4950928 and its role on asthma exacerbations in a population of children and young adults with asthma.

METHODS

A cross-sectional survey was undertaken using medical records and direct interviews of 1,071 children and young adults with asthma, aged 3 to 22 years, from Scotland. Saliva samples were collected for genotyping. Binary logistic regression was used to calculate odds ratios (ORs) and P-values for measures of asthma exacerbations.

RESULTS

The minor -131G allele confers protection against asthma-related hospital admissions (OR = 0.62; 95% CI 0.41-0.92; P = .018) in children and young adults with asthma.

CONCLUSIONS

Our study shows that rs4950928 is significantly associated with hospital admissions in children and young adults; screening for rs4950928 may predict asthma-related hospital admissions, and through individually defined treatment management plans, potentially reduce health care costs.

Fluticasone reverses oxymetazoline-induced tachyphylaxis of response and rebound congestion

RATIONALE

Chronic use of intranasal decongestants, such as oxymetazoline, leads to tachyphylaxis of response and rebound congestion, caused by alpha-adrenoceptor mediated down-regulation and desensitization of response.

OBJECTIVES

We evaluated if tachyphylaxis can be reversed by intranasal fluticasone propionate, and the relative alpha(1)- and alpha(2)-adrenoceptor components of tachyphylaxis using the alpha(1)-antagonist prazosin.

METHODS

In a randomized, double-blind, placebo-controlled, crossover design, 19 healthy subjects received intranasal oxymetazoline, 200 microg three times a day for 14 days, followed by the addition of fluticasone, 200 microg twice a day for a further 3 days. At Days 1, 14, and 17, participants received a single dose of oral prazosin, 1 mg, or placebo with measurements made before and 2 hours later.

MEASUREMENTS AND MAIN RESULTS

Outcomes evaluated were peak nasal inspiratory flow, nasal resistance, blood flow, and oxymetazoline dose-response curve (DRC). On Day 14 versus Day 1, inspiratory flow decreased (mean difference, 95% confidence interval) (-47.9 L x min(-1); -63.9 to -31.9; P < 0.001) and the DRC shifted downward (24.8 L x min(-1); 20.3-29.3; P < 0.001). On Day 17 versus Day 14, after fluticasone, inspiratory flow increased (45 L x min(-1); 30-61; P < 0.001) and the DRC shifted upward (26.2 L x min(-1); 21.7-30.7; P < 0.001). On Day 1, prazosin reduced inspiratory flow (-52.6 L x min(-1); -19.2 to -86) compared with baseline. This effect was abolished on Day 14 (7.9 L x in(-1); -41.3 to 25.5).

CONCLUSIONS

Oxymetazoline-induced tachyphylaxis and rebound congestion are reversed by intranasal fluticasone. Further studies are indicated to evaluate if combination nasal sprays of decongestant and corticosteroid are an effective strategy to obviate tachyphylaxis and rebound in rhinitis. Clinical trial registered with www.clinicaltrials.gov (NCT 00487032).

Inhaled salmeterol and/or fluticasone alters structure/function in a murine model of allergic airways disease

BACKGROUND

The relationship between airway structural changes (remodeling) and airways hyperresponsiveness (AHR) is unclear. Asthma guidelines suggest treating persistent asthma with inhaled corticosteroids and long acting beta-agonists (LABA). We examined the link between physiological function and structural changes following treatment fluticasone and salmeterol separately or in combination in a mouse model of allergic asthma.

METHODS

BALB/c mice were sensitized to intraperitoneal ovalbumin (OVA) followed by six daily inhalation exposures. Treatments included 9 daily nebulized administrations of fluticasone alone (6 mg/ml), salmeterol (3 mg/ml), or the combination fluticasone and salmeterol. Lung impedance was measured following methacholine inhalation challenge. Airway inflammation, epithelial injury, mucus containing cells, and collagen content were assessed 48 hours after OVA challenge. Lungs were imaged using micro-CT.

RESULTS AND DISCUSSION

Treatment of allergic airways disease with fluticasone alone or in combination with salmeterol reduced AHR to approximately naüve levels while salmeterol alone increased elastance by 39% compared to control. Fluticasone alone and fluticasone in combination with salmeterol both reduced inflammation to near naive levels. Mucin containing cells were also reduced with fluticasone and fluticasone in combination with salmeterol.

CONCLUSIONS

Fluticasone alone and in combination with salmeterol reduces airway inflammation and remodeling, but salmeterol alone worsens AHR: and these functional changes are consistent with the concomitant changes in mucus metaplasia.

Budesonide prevents cytokine-induced decrease of the relaxant responses to formoterol and terbutaline, but not to salmeterol, in mouse trachea

During asthma exacerbations, increased airway inflammation may impair the effects of beta(2)-adrenoceptor (beta(2)AR) agonists. It is unclear whether this impairment is prevented by inhaled glucocorticoids (GCs). We have investigated the relaxation of carbachol-contracted mouse tracheal segments to the beta(2)AR agonists formoterol, terbutaline, and salmeterol. The segments were pre-exposed for 4 days to the proinflammatory cytokines tumor necrosis factor alpha (100 ng/ml) and interleukin-1beta (10 ng/ml) with or without the GC, budesonide (1 microM). Formoterol and terbutaline induced greater maximal relaxation (R(max)) than salmeterol. The cytokines decreased R(max) of all beta(2)AR agonists, whereas budesonide had no effect. However, after concomitant treatment with cytokines and budesonide, the R(max) values of formoterol and terbutaline were not impaired, whereas budesonide did not prevent the decrease in the R(max) of salmeterol. A similar pattern was observed for cAMP production by the agonists. In tracheal smooth muscle, beta(2)AR mRNA was not affected by the cytokines but increased with budesonide. However, the cytokines markedly increased cyclooxygenase (COX)-2 mRNA expression, which may lead to heterologous desensitization of beta(2)AR. It is noteworthy that the cytokine-induced increase of COX-2 was blocked by concomitant budesonide suggesting that heterologous desensitization of beta(2)AR by the cytokines may be prevented by budesonide treatment. Budesonide prevented cytokine-induced impairment of the tracheal relaxation and beta(2)AR/cAMP signaling for formoterol but not for salmeterol. This suggests that differences exist between formoterol and salmeterol in beta(2)AR coupling/activation and/or signal transduction upstream of cAMP. These results imply that maximal bronchodilator effects of formoterol, but not of salmeterol, are maintained by budesonide treatment during periods with increased inflammation, such as asthma exacerbations.

SH2-B beta expression in alveolar macrophages in BAL fluid of asthmatic guinea pigs and its role in NGF-TrkA-mediated asthma

BACKGROUND AND OBJECTIVE

Nerve growth factor (NGF)/tyrosine kinase receptor A (TrkA) signalling may play an important role in the pathogenesis of asthma, and SH2-B beta, a TrkA-binding protein, modulates the NGF signalling pathway. In this study, SH2-B beta expression in alveolar macrophages (AM) in guinea pig BAL fluid and its role in asthma pathogenesis through the NGF-TrkA signalling pathway were investigated.

METHODS

Guinea pigs were randomized into five groups: control, a model of asthma, anti-SH2-B beta antibody treatment, anti-NGF antibody treatment and anti-TrkA antibody treatment. The asthmatic model was established in guinea pigs by inhalation of ovalbumin. Specific anti-SH2-B beta, anti-NGF and anti-TrkA antibodies were administered and AM were isolated from BAL fluid to assess SH2-B beta expression using an immunofluorescence assay. SH2-B beta and TrkA protein expression were determined by western blotting, IL-1 beta and IL-4 levels in the BAL fluid supernatants were determined by ELISA, and pathological changes in the bronchi and lung tissues were examined by HE staining.

RESULTS

Lymphocyte, eosinophil and total inflammatory cell numbers in BAL fluid were significantly higher in the asthma model group than in the other groups (P < 0.01). NGF expression in the asthma model group was significantly higher than that in the PBS control group (P < 0.01). SH2-B beta was expressed in AM of control animals and expression was significantly higher in the asthma model than in the other groups (P < 0.01). TrkA protein expression was significantly higher in the asthma model group than in the PBS group (P < 0.01), and treatment with anti-NGF antibody resulted in significant reduction of TrkA expression (P < 0.01).

CONCLUSIONS

SH2-B beta is expressed in AM of normal guinea pigs, and SH2-B beta may participate in asthma pathogenesis through the NGF-TrkA signalling pathway.

Acute and chronic lung function responses to salmeterol and salmeterol plus fluticasone propionate in relation to Arg16Gly beta(2)-adrenergic polymorphisms

OBJECTIVE

There is conflicting clinical evidence describing the response to long-acting beta-agonist (LABA) bronchodilators for patients with Arg16Gly beta(2)-adrenergic receptor (ADRB2 ) genotype differences. Furthermore, the role of inhaled corticosteroids (ICS) in modulating Arg16Gly clinical responses is not well understood. The objective of this study was to investigate the effects of Arg16Gly polymorphism on the 12 hour post-dose bronchodilator response to the LABA salmeterol (SAL) or SAL plus fluticasone propionate (FSC) on first administration and following 12 weeks of treatment.

RESEARCH DESIGN AND METHODS

Genotyping was retrospectively performed in patients with persistent asthma randomized to SAL or FSC who were participating in three similar double-blind clinical trials of 12 week duration. The primary outcome was area under the curve (AUC) for 12 hour serial FEV(1) by treatment and Arg16Gly genotype, recorded on Day 1 and Week 12. In addition, other single nucleotide polymorphisms (SNPs) associated with asthma outcomes we assessed at positions -47, +79 and +491 as well as common ADRB2 haplotypes.

RESULTS

No statistically significant associations between Arg16Gly genotypes and serial FEV(1) clinical responses to SAL and FSC were observed following acute assessment. In addition, the FEV(1) response was preserved following 12 weeks of treatment with SAL and FSC and was not altered by Arg16Gly genotypes analyzed. These results may not be generalizable to other ethnic groups since they are derived predominantly from Caucasians.

CONCLUSIONS

In subjects with persistent asthma, the ADRB2 Arg16Gly polymorphism does not alter lung function responses to SAL or FSC over the 12 hour dosing interval following acute and chronic dosing.

Endotyping asthma: new insights into key pathogenic mechanisms in a complex, heterogeneous disease

Clinical asthma is very widely assumed to be the net result of excessive inflammation driven by aberrant T-helper-2 (Th2) immunity that leads to inflamed, remodelled airways and then functional derangement that, in turn, causes symptoms. This notion of disease is actually poorly supported by data, and there are substantial discrepancies and very poor correlation between inflammation, damage, functional impairment, and degree of symptoms. Furthermore, this problem is compounded by the poor understanding of the heterogeneity of clinical disease. Failure to recognise and discover the underlying mechanisms of these major variants or endotypes of asthma is, arguably, the major intellectual limitation to progress at present. Fortunately, both clinical research and animal models are very well suited to dissecting the cellular and molecular basis of disease endotypes. This approach is already suggesting entirely novel pathways to disease-eg, alternative macrophage specification, steroid refractory innate immunity, the interleukin-17-regulatory T-cell axis, epidermal growth factor receptor co-amplification, and Th2-mimicking but non-T-cell, interleukins 18 and 33 dependent processes that can offer unexpected therapeutic opportunities for specific patient endotypes.

Differences in the pharmacodynamics of budesonide/formoterol and salmeterol/fluticasone reflect differences in their therapeutic usefulness in asthma

Although the available inhaled corticosteroid (ICS)/long-acting beta( 2)-agonist (LABA) combinations principally work in a similar fashion, they differ in several important ways, leading to different efficacy. The ICS/LABA combination product budesonide/formoterol can be used as both maintenance and reliever therapy, providing a fixed maintenance dose, which does not change, and replacing short-acting beta(2)-agonists as relievers thereby allowing intervention to address the underlying inflammation at the earliest sign of symptomatic worsening. This approach is not suitable for other combination products such as salmeterol/fluticasone. Here we review the pharmacological differences of budesonide/ formoterol and salmeterol/fluticasone that permit the use of budesonide/formoterol as both maintenance and reliever therapy.

Synergistic effects of fluticasone propionate and salmeterol on inhibiting rhinovirus-induced epithelial production of remodelling-associated growth factors

BACKGROUND

Rhinoviruses (RV), the major trigger of acute asthma exacerbations, are able to infect bronchial epithelium and induce production of pro-inflammatory, but also angiogenic and pro-fibrotic mediators. Fluticasone propionate (FP) and salmeterol (S) are clinically effective and act synergistically in controlling persistent asthma; however, their effect on virus-associated asthma is less clear.

AIM

The aim of this study was to assess the individual and combined effects of FP and S on RV-induced epithelial production of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2).

METHODS

Bronchial epithelial cells (BEAS-2B) were exposed in vitro to RV and were subsequently treated with FP and S, at physiologically relevant concentrations, alone or in combination. VEGF and FGF-2 were measured in the supernatants of these cultures using ELISA.

RESULTS

FP was able to reduce RV-induced VEGF production in a dose-dependent manner. S also induced a smaller reduction; addition of both factors inhibited VEGF synergistically. FGF-2 production was not inhibited by either FP or S alone, but was significantly reduced when both substances were present in the culture.

CONCLUSION

This study demonstrates that FP and S may synergistically inhibit the production of angiogenic and/or pro-fibrotic factors that are induced after RV infection of BEAS-2B and are implicated in airway remodelling, suggesting that this combination may represent an important therapeutic option on virus-induced asthma.

Current issues with beta2-adrenoceptor agonists: pharmacology and molecular and cellular mechanisms

Beta2-adrenoceptors are widely, almost ubiquitously, expressed. Activation of these receptors on bronchial smooth muscle by short- and long-acting beta2-adrenoceptor agonists causes bronchodilation. Here, the beta2-adrenoceptor is linked by the G protein, Gs, to adenylyl cyclase, which increases cyclic adenosine monophosphate (cAMP), thus activating protein kinase A, which affects calcium levels and reduces the efficiency of myosin light-chain kinase, causing relaxation. Activation also entrains numerous acute and longer term downregulation responses affecting the number, location, and net efficiency of signaling of the receptor. Synthetic beta2-agonists are all "partial agonists," incompletely able to optimally stimulate cAMP signal transduction. However, compared with some cells (such as mast cells) involved in exercise- induced asthma induction, airway smooth muscle is privileged in that transduction efficiency is intrinsically high and the tissue is very resistant to complete downregulation. Glucocorticosteroids have broadly beneficial interactions with beta2-adrenoceptors. Researchers have recently discovered that the beta2-adrenoceptor may function as a homodimer and that it can form heterodimers with both the beta1- and beta3-adrenoceptors, and possibly other receptors. This further complicates interpretation of the effect of beta2-adrenoceptor polymorphisms, but it is unknown whether this occurs in humans in vivo. Researchers have known for some time that strong contraction involving receptors coupled to the Gq G protein (e.g., cholinergic and leukotriene receptors via negative biochemical crosstalk), virus infection (via uncoupling), and inflammation (via kinases) can impair relaxation. Most recently, researchers have discovered that the beta2-adrenoceptor can also send potentially adverse signals after "atypical coupling" to Gq rather than Gs. The clinical implications of these uncouplings, crosstalk, and atypical coupling possibilities are not well-understood.

Autonomic nervous system control of the cardiovascular and respiratory systems in asthma

Patients with asthma have exaggerated bronchoconstriction of their airways in response to certain indirect (e.g. cold air, allergens, dust, exercise) or direct (e.g. inhaled methacholine) stimuli. This 'hyper-reactivity' usually co-exists with airway inflammation, although the pathophysiological mechanisms underlying these changes are not fully understood. It is likely that this hyper-reactivity is associated with abnormal autonomic nervous system (ANS) control. In particular, the parasympathetic (vagal) component of the ANS appears to be implicated in the pathogenesis of asthma. In addition, several studies have suggested the existence of differential alteration in ANS function following exercise in asthmatics compared with non-asthmatic individuals. Several early studies suggested that the altered autonomic control of airway calibre in asthma might be reflected by a parallel change in heart rate. Cardiac vagal reactivity does indeed appear to be increased in asthma, as demonstrated by the cardiac response to various autonomic functions tests. However, other studies have reported a lack of association between bronchial and cardiac vagal tone, and this is in accord with the concept of system-independent ANS control. This review provides a discussion of cardiovascular-autonomic changes associated with either the pathophysiology of asthma per se or with asthma pharmacotherapy treatment. Previous investigations are summarised suggesting an apparent association between altered autonomic-cardiovascular control and bronchial asthma. The full extent of autonomic dysfunction, and its clinical implications, has yet to be fully determined and should be the subject of future investigation.

Long-acting beta2-agonists: comparative pharmacology and clinical outcomes

Salmeterol and formoterol are both long-acting beta(2)-adrenoceptor agonists (beta(2)-agonists). They both provide excellent bronchodilating and bronchoprotective effects in patients with asthma but their are some differences between these two long-acting beta(2)-agonists in vitro and in vivo. Formoterol has a greater potency and intrinsic activity than salmeterol, which can become especially apparent at higher doses than that clinically recommended, and in contracted bronchi. Long-term use of long-acting beta(2)-agonists can induce tolerance, which can be partially reversed with corticosteroids. Long-acting beta(2)-agonists have some anti-inflammatory effects in vitro, but data in vivo are less convincing. Compared with doubling the dose of inhaled corticosteroids, the addition of inhaled long-acting beta(2)-agonists to inhaled corticosteroids improves symptom control in patients with asthma and reduces both the exacerbation rate of asthma and hospital admission rate. No enhanced airway responsiveness or loss of perception of dyspnea has been observed with the use of inhaled long-acting beta(2)-agonists. Monotherapy with long-acting beta(2)-agonists is not recommended.

What is new with the beta2-agonists: issues in the management of asthma

OBJECTIVE

To review the more recent literature addressing the issue of whether beta2-agonists can worsen asthma and/or increase the risk of severe exacerbations and death from asthma.

DATA SOURCES

PubMed was searched (2001-December 2004), along with the Food and Drug Administration and Cochrane Library Web sites. In addition, the bibliographies of recent reviews of the subject were assessed.

STUDY SELECTION AND DATA EXTRACTION

Randomized clinical trials, retrospective and prospective cohort studies, and meta-analyses published in the past 3 years were reviewed. Studies assessing the potential for beta2-agonists to worsen outcomes in asthma as well as long-term studies assessing asthma outcomes that included an arm with regular administration of short- or long-acting inhaled beta2-agonists (LABAs) were selected. Worsening asthma was defined as a decline in lung function, an increase in bronchial hyperresponsiveness, exacerbations, or death. Studies older than 3 years selected from the bibliographies of the primary articles that addressed background perspective were also included where appropriate.

DATA SYNTHESIS

The studies fell into 3 primary categories with some overlap: those assessing toxicity of the S-enantiomer of albuterol, those evaluating the risk of specific genotypes regarding worsening asthma, and those assessing asthma outcomes with LABA therapy.

CONCLUSIONS

The current data on the use of beta2-agonists continue to support the national and international guidelines for the treatment of asthma. That is, short-acting inhaled beta2-agonists should only be used as needed for symptoms and prevention of exercise-induced bronchospasm, and LABAs should only be used regularly as adjunctive therapy with inhaled corticosteroids in patients whose asthma is not controlled with low to medium doses of the inhaled corticosteroid.

Pharmacology of airway inflammation in asthma and COPD

The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term treatment. Although inhaled glucocorticoids are highly effective in controlling airway inflammation in asthma, they are ineffective in the small group of patients with glucocorticoid-dependent and -resistant asthma. With very few exceptions, COPD is caused by tobacco smoking, and smoking cessation is the only truly effective treatment of COPD available. Current pharmacological treatment of COPD is unsatisfactory, as it does not significantly influence the severity of the disease or its natural course. Glucocorticoids are scarcely effective in COPD patients without concomitant asthma. Bronchodilators improves symptoms and quality of life, in COPD patients, but, with the exception of tiotropium, they do not significantly influence the natural course of the disease. Theophylline is the only drug which has been demonstrated to have a significant effect on airway inflammation in patients with COPD. Here we review the pharmacology of currently used antiinflammatory therapies for asthma and COPD and their proposed mechanisms of action. Recent understanding of disease mechanisms in severe steroid-dependent and -resistant asthma and in COPD, has lead to the development of novel compounds, which are in various stages of clinical development. We review the current status of some of these new potential drugs.

Inhaled salmeterol/fluticasone propionate combination: a pharmacoeconomic review of its use in the management of asthma

Asthma guidelines recommend an inhaled corticosteroid plus a long-acting inhaled beta(2)-agonist (beta(2)-adrenoceptor agonist) as the preferred maintenance therapy for moderate and severe persistent asthma. Advair/Seretide Diskus also registered as Accuhaler is fixed-dose salmeterol (a long-acting inhaled beta(2)-agonist) and fluticasone propionate (a corticosteroid) administered via a single powder inhalation device. The clinical effectiveness of salmeterol/fluticasone propionate in patients with persistent asthma symptoms has been established in comparative clinical trials. Pharmacoeconomic analyses, based on data from these clinical trials, have been conducted from a healthcare payer perspective in various countries. In patients with asthma not controlled with inhaled corticosteroids, salmeterol/fluticasone propionate was associated with more favourable (lower) cost-effectiveness ratios than fluticasone propionate monotherapy, oral montelukast plus inhaled fluticasone propionate, inhaled budesonide, and inhaled formoterol plus budesonide. As the initial maintenance therapy in patients with persistent asthma symptoms while receiving short-acting beta(2)-agonists alone, salmeterol/fluticasone propionate was cost effective relative to montelukast monotherapy. Although the total cost of asthma management tended to be slightly higher with salmeterol/fluticasone propionate than with fluticasone propionate or montelukast monotherapy, salmeterol/fluticasone propionate consistently had a more favourable cost-effectiveness ratio in terms of per successfully treated week or symptom-free day and/or was associated with small incremental costs to achieve significant additional clinical benefits. In clinical practice, salmeterol plus fluticasone propionate was associated with lower asthma-related costs than treatment with other maintenance therapies.In patients with asthma symptoms despite treatment with inhaled corticosteroids, salmeterol/fluticasone propionate produced clinically meaningful improvements in overall Asthma Quality of Life Questionnaire (AQLQ) scores relative to salmeterol or placebo monotherapy, in emotional function domain scores relative to fluticasone propionate or budesonide, and in asthma symptoms domain scores relative to budesonide. In patients with persistent asthma symptoms while receiving short-acting beta(2)-agonists alone, salmeterol/fluticasone propionate produced clinically meaningful improvements in overall AQLQ scores compared with fluticasone propionate or montelukast.

CONCLUSIONS

Pharmacoeconomic analyses indicate that salmeterol/fluticasone propionate administered via a single inhaler represents a cost-effective treatment option (relative to fluticasone propionate at the same nominal dosage, budesonide, formoterol plus budesonide and montelukast plus fluticasone propionate) in patients with asthma not controlled with inhaled corticosteroid therapy. In patients with asthma not controlled with short-acting beta(2)-agonists alone, salmeterol/fluticasone propionate is a cost effective treatment relative to monotherapy with montelukast. Importantly, salmeterol/fluticasone propionate is also associated with improvements in health-related quality of life.

In vitro sensitization of human bronchus by beta2-adrenergic agonists

Incubation of human distal bronchi from 48 patients for 15 h with 10(-7) M fenoterol induced sensitization characterized by an increase in maximal contraction to endothelin-1 (ET-1) and acetylcholine (ACh). Incubation of human bronchi with 10(-6), 3 x 10(-6), and 10(-5) M forskolin (an adenyl cyclase activator) reproduced sensitization to ET-1 and ACh. The sensitizing effect of fenoterol was inhibited by coincubation with gliotoxine (a nuclear factor-kappaB inhibitor), dexamethasone, indomethacin (a cyclooxygenase inhibitor), GR-32191 (a TP prostanoid receptor antagonist), MK-476 (a cysteinyl leukotriene type 1 receptor antagonist), SR-140333 + SR-48968 + SR-142801 (neurokinin types 1, 2, and 3 tachykinin receptor antagonists) with or without HOE-140 (a bradykinin B(2) receptor antagonist), SB-203580 (an inhibitor of the 38-kDa mitogen-activated protein kinase, p38(MAPK)), or calphostin C (a protein kinase C blocker). Our results suggest that chronic exposure to fenoterol induces proinflammatory effects mediated by nuclear factor-kappaB and pathways involving leukotrienes, prostanoids, bradykinin, tachykinins, protein kinase C, and p38(MAPK), leading to the regulation of smooth muscle contraction to ET-1 and ACh.

Effect of combining salmeterol and fluticasone on the progression of airway remodeling

In subjects insufficiently controlled with low to moderate doses of inhaled corticosteroids, adding beta-agonists is clinically more beneficial than increasing the dose of inhaled corticosteroids. In the present study, we investigated the effect of adding salmeterol to fluticasone on allergen-induced airway inflammation and remodeling. Sensitized rats, in which characteristics of remodeling had been induced by ovalbumin exposure every 2 days from Days 14 to 28, were further exposed to ovalbumin or PBS from Days 29 to 42. During the last 2 weeks, before allergen exposure, rats were treated with aerosolized fluticasone propionate (10 mg), salmeterol (1 mg), salmeterol (1 mg) plus fluticasone propionate (10 mg), or placebo. After 4 weeks of ovalbumin exposure, the airways showed inflammatory changes, goblet cell hyperplasia, and enhanced fibronectin and collagen deposition. Salmeterol in monotherapy decreased bronchoalveolar lavage fluid eosinophil number but had no influence on structural changes. Combining salmeterol with fluticasone propionate counteracted goblet cell hyperplasia, but increased the amount of fibronectin and collagen in the airway wall. These effects of salmeterol did not influence airway responsiveness. We conclude that the combination of salmeterol and fluticasone propionate enhances aspects of allergen-induced airway remodeling. This is not accompanied by changes in airway responsiveness.

Tumor necrosis factor-alpha-induced secretion of RANTES and interleukin-6 from human airway smooth muscle cells: modulation by glucocorticoids and beta-agonists

Recent studies have demonstrated that tumor necrosis factor (TNF)-alpha stimulates the secretion of interleukin (IL)-6 and regulated on activation, normal T cells expressed and secreted (RANTES) from airway smooth muscle (ASM) cells, with the induction of each molecule being differentially regulated (IL-6 increased, RANTES inhibited) by cyclic adenosine monophosphate (cAMP)-elevating agents. In this study we identify the mechanisms mediating IL-6 and RANTES gene transcription in human ASM cells. We found that TNF-alpha induced IL-6 gene expression in ASM cells via a nuclear factor (NF)-kappaB-dependent pathway, whereas RANTES gene expression was mediated via activation of activator protein (AP)-1 and nuclear factor of activated T cells (NF-AT). TNF-alpha-induced IL-6 secretion was only partially inhibited by dexamethasone, yet TNF-alpha-induced RANTES secretion was abolished. beta-Agonists induced IL-6 secretion from ASM via activation of the CRE region of the IL-6 promoter. beta-Agonists augmented TNF-alpha-induced IL-6 secretion, reflecting an additive effect of NF-kappaB and CRE response elements on IL-6 gene expression. In contrast, beta-agonists inhibited TNF-alpha-induced RANTES secretion via an AP-1-independent pathway. Collectively, these data elucidate transcriptional mechanisms mediating TNF-alpha-induced IL-6 and RANTES secretion from ASM cells, and identify the specific cis- or trans-acting elements that determine the differential effects of glucocorticoids and cAMP-elevating agents on the expression of these genes.

Advair: combination treatment with fluticasone propionate/salmeterol in the treatment of asthma

Several classes of medications are available for the treatment of asthma, and often they must be taken concurrently to achieve asthma control. Based on the understanding of asthma as an inflammatory disease, the National Heart Lung and Blood Institute guidelines provide a stepwise approach to pharmacologic therapy. Corticosteroid therapy, principally inhaled corticosteroid (ICS) therapy, is considered the most effective anti-inflammatory treatment. In cases of moderate-to-severe persistent asthma, the addition of a second long-term control medication to ICS therapy is one recommended treatment option. A combination-product inhaler (Advair, Seretide) was developed to treat both the inflammatory and bronchoconstrictive components of asthma by delivering a dose of the ICS, fluticasone propionate, and a dose of the long-acting beta2-adrenergic (LABA) bronchodilator, salmeterol. The Advair Diskus is available in 3 strengths of fluticasone propionate (100, 250, and 500 microg) and a fixed dose (50 microg) of salmeterol. Combination treatment with both ICS and LABA provides greater asthma control than increasing the ICS dose alone, while at the same time reducing the frequency and perhaps the severity of exacerbations. Furthermore, salmeterol added to ICS therapy provides superior asthma control compared with the addition of leukotriene modifiers or theophylline. The superior control is likely a consequence of the complementary actions of the drugs when taken together, including the activation of the glucocorticoid receptor by salmeterol. By combining anti-inflammatory treatment with a long-acting beta2-agonist in a single inhaler (1 inhalation twice daily), physicians can provide coverage for both the inflammatory and bronchoconstrictive aspects of asthma without introducing any new or unexpected adverse consequences. The most common drug-related adverse events were those known to be attributable to the constituent medications (ICS therapy and/or LABA therapy). Although the benefits of combined ICS plus LABA therapy can be achieved with separate inhalers, the convenience of the combination product may improve patient adherence and may therefore reduce the morbidity of asthma.

Long-acting beta2 agonists in the management of stable chronic obstructive pulmonary disease

Long-acting beta2 agonist bronchodilators (e.g. formoterol, salmeterol) are a new interesting therapeutic option for patients with chronic obstructive pulmonary disease (COPD). In the short term, both salmeterol and formoterol appear to be more effective than short-acting beta2 agonists, and in patients with stable COPD they are more effective than anticholinergic agents and theophylline. Regular treatment of patients with COPD with long-acting beta2 agonists can induce an improvement in the respiratory function and certain aspects of quality of life. Moreover, salmeterol seems to be better than ipratropium and theophylline in improving lung function at the recommended doses after a long term treatment. Use of combination therapy of a long-acting inhaled beta2 agonist and an anticholinergic agent or theophylline in patients with COPD has not been sufficiently studied. Combination of usual doses of ipratropium or oxitropium with usual doses of salmeterol or formoterol does not appear to improve pulmonary function, but this lack of improvement with the combination should not, in itself, prevent implementation of further therapeutic steps in patients responsive to an anticholinergic agent and/or salmeterol or formoterol administered singly. Neither formoterol nor salmeterol elicit significant cardiovascular effects in healthy individuals and patients with reversible airway obstruction. However, adverse cardiac events might occur in patients with COPD with pre-existing cardiac arrhythmias and hypoxaemia if they use long-acting 12 agonists, although the recommended single dose of salmeterol 50 microg or formoterol 12 microg ensures a relatively higher safety margin than formoterol 24 microg. The bronchodilatory effect of long-acting beta2 agonists seems to be fairly stable after regular treatment with these bronchodilators. Moreover, pre-treatment with a conventional dose of formoterol or salmeterol does not preclude the possibility of inducing further bronchodilation with salbutamol in patients with partially reversible COPD. All these findings support the use of long-acting beta2 agonist bronchodilators as first-line bronchodilator therapy for the long term treatment of airflow obstruction in patients with COPD. However, since physicians must always choose a drug that is highly efficacious, well tolerated and inexpensive, the cost-effectiveness analysis in relation to other bronchodilators will determine the proper place of long-acting beta2 agonists in the long term therapy of stable COPD.