Long-acting beta2-agonists in asthma: not so SMART?

Exacerbation of ozone-induced pulmonary and systemic effects by β2-adrenergic and/or glucocorticoid receptor agonist/s

Agonists of β₂ adrenergic receptors (β₂AR) and glucocorticoid receptors (GR) are prescribed to treat pulmonary diseases. Since ozone effects are mediated through the activation of AR and GR, we hypothesized that the treatment of rats with relevant therapeutic doses of long acting β₂AR agonist (LABA; clenbuterol; CLEN) and/or GR agonist (dexamethasone; DEX) would exacerbate ozone-induced pulmonary and systemic changes. In the first study, male 12-week-old Wistar-Kyoto rats were injected intraperitoneally with vehicle (saline), CLEN (0.004 or 0.02 mg/kg), or DEX (0.02 or 0.1 mg/kg). Since dual therapy is commonly used, in the second study, rats received either saline or combined CLEN + DEX (each at 0.005 or 0.02 mg/kg) one day prior to and on both days of exposure (air or 0.8ppm ozone, 4 hr/day x 2-days). In air-exposed rats CLEN, DEX or CLEN + DEX did not induce lung injury or inflammation, however DEX and CLEN + DEX decreased circulating lymphocytes, spleen and thymus weights, increased free fatty acids (FFA) and produced hyperglycemia and glucose intolerance. Ozone exposure of vehicle-treated rats increased bronchoalveolar lavage fluid protein, albumin, neutrophils, IL-6 and TNF-α. Ozone decreased circulating lymphocytes, increased FFA, and induced hypeerglycemia  and glucose intolerance. Drug treatment did not reverse ozone-induced ventillatory changes, however, lung effects (protein and albumin leakage, inflammation, and IL-6 increase) were exacerbated by CLEN and CLEN + DEX pre-treatment in a dose-dependent manner (CLEN > CLEN + DEX). Systemic effects induced by DEX and CLEN + DEX but not CLEN in air-exposed rats were analogous to and more pronounced than those induced by ozone. These data suggest that adverse air pollution effects might be exacerbated in people receiving LABA or LABA plus glucocorticoids.

N-of-1 trials in the clinical care of patients in developing countries: a systematic review

BACKGROUND

N-of-1 trials have a potential role in promoting patient-centered medicine in developing countries. However, there is limited academic literature regarding the use of N-of-1 trials in the clinical care of patients in resource-poor settings.

OBJECTIVE

To assess the extent of use, purpose and treatment outcome of N-of-1 trials in developing countries.

METHOD

A systematic review of clinical N-of-1 trials was conducted between 1985 and September 2015 using PubMed, Embase, CINAHL, Web of Science and the Cochrane Central Register of Controlled Trials. Grey literature databases and clinical trial registers were also searched. This review included randomized, multi-cycle, crossover within individual patient trials involving drug intervention. Quality assessment and data extraction were conducted by two independent reviewers.

RESULT

Out of 131 N-of-1 trials identified, only 6 (4.5%) were conducted in developing countries. The major reason that N-of-1 trials were used was to provide evidence on feasibility, effectiveness and safety of therapies. A total of 72 participants were involved in these trials. Five of the studies were conducted in China and all evaluated Chinese traditional medicine. The remaining study was conducted in Brazil. The completion rate was 93%. More than half, 46 (69%) of subjects made medication changes consistent with trial results after trial completion. A number of threats to the validity of the included evidence limited the validity of the evidence. In particular, the estimated overall effect in four of the included studies could have been affected by the "carry over" of the previous treatment effect as no adequate pharmacokinetic evidence regarding traditional medicines was presented.

CONCLUSION

The prevalence and scope of N-of-1 trials in developing countries is low. A coordinated effort among government, clinicians, researchers and sponsor organizations is needed to increase their uptake and quality in developing countries.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015026841 .

The evidence on tiotropium bromide in asthma: from the rationale to the bedside

Severe and poorly controlled asthma still accounts for a great portion of the patients affected. Disease control and future risk management have been identified by international guidelines as the main goals in patients with asthma. The need for new treatment approaches has led to reconsider anticholinergic drugs as an option for asthma treatment. Tiotropium is the first anticholinergic drug that has been approved for children and adults with poorly controlled asthma and is currently considered as an option for steps 4 and 5 of the Global Initiative for Asthma. In large randomized clinical trials enrolling patients with moderate to severe asthma, add-on therapy with tiotropium has demonstrated to be efficacious in improving lung function, decreasing risk of exacerbation and slowing the worsening of disease; accordingly, tiotropium demonstrated to be non inferior compared to long acting beta-agonists in the maintenance treatment along with medium to high inhaled corticosteroids. In view of the numerous ancillary effects acting on inflammation, airway remodeling, mucus production and cough reflex, along with the good safety profile and the broad spectrum of efficacy demonstrated in different disease phenotypes, tiotropium can represent a beneficial alternative in the therapeutic management of poorly controlled asthma. The present extensive narrative review presents the pharmacological and pathophysiological basis that guided the rationale for the introduction of tiotropium in asthma treatment algorithm, with a particular focus on its conventional and unconventional effects; finally, data on tiotropium efficacy and safety. from recent randomized clinical trials performed in all age categories will be extensively discussed.

Prescription patterns in asthma patients initiating salmeterol in UK general practice: a retrospective cohort study using the General Practice Research Database (GPRD)

BACKGROUND

An association between salmeterol, a long-acting β(2)-agonist (LABA), use and rare serious asthma events or asthma mortality was observed in two large clinical trials. This has resulted in heightened scrutiny of LABAs and comprehensive reviews by regulatory agencies.

OBJECTIVE

The aim of this retrospective observational cohort study was to better characterize salmeterol medication use patterns in the UK. We describe asthma prescription patterns in a cohort of patients (n =17,745) in the General Practice Research Database who initiated treatment with salmeterol-containing prescriptions between 2003 and 2006, including salmeterol and salmeterol/fluticasone propionate in a single device.

METHODS

Prescriptions patterns by medication class, including concurrent prescription of salmeterol with inhaled corticosteroids (ICS), were described using 6-month intervals in the 1-year period before and after the salmeterol-containing index prescription.

RESULTS

In the 0- to 6-month and 7- to 12-month periods prior to initiation of the salmeterol-containing prescription, the cohort experienced worsening of asthma, measured by an increase in the proportion of patients with prescriptions for short-acting β-agonists [SABA] (73-89%), ICS (70-81%) and systemic corticosteroids (14-28%). Nearly all patients prescribed salmeterol were concurrently prescribed ICS (≥95% within 90 days). In the 12 months following initiation of the salmeterol-containing prescription, a decrease in asthma prescriptions was observed.

DISCUSSION

These results support the appropriate prescribing of salmeterol-containing medications, as per recommendations in asthma treatment guidelines in the UK.

CONCLUSION

Salmeterol was consistently prescribed as an add-on asthma-controller with an ICS for most patients, and was associated with improvements in asthma control, as indicated by decreases in SABA and systemic corticosteroid prescriptions following salmeterol introduction.

Risk of serious asthma exacerbations associated with long-acting beta agonists among patients with asthma: a retrospective cohort study

BACKGROUND

After the Serevent Nationwide Surveillance clinical trial, controversy has surrounded the safety of long-acting beta agonists (LABAs).

OBJECTIVE

Examine the association between LABAs and severe asthma exacerbations (SAEs).

METHODS

From a multistate Medicaid database, for the years 2002-2007, a total of 940,449 patients (age <40) with asthma were selected and divided into a cohort with newly-diagnosed asthma and one with pre-existing asthma. SAEs included asthma-related emergency department (ED) visits, hospitalizations, and intubations. Patients' asthma severity was determined based on medication regimen as suggested by the 2002 National Asthma Guidelines. Specific use of inhaled corticosteroids (ICSs), LABAs, ICS/LABA combination drugs, short-acting beta agonists (SABAs), and other drugs was tracked. Cox proportional hazard regressions were estimated to assess the risk of SAEs associated with patient severity, drug use, and covariates.

RESULTS

Compared to patients taking a SABA only, estimated SAE hazard ratios for newly diagnosed and pre-existing-asthma patients were as follows: 0.63 (95% CI 0.58-0.69) and 0.74 (0.70-0.79) for patients on a LABA without ICS, and 0.79 (0.77-0.81) and 0.90 (0.87-0.92) for those on a LABA/ICS single inhaler. Although hazard ratios were estimated to be similar for ED visits, LABA use was found to be positively associated with hospitalizations and intubations. Other key risk factors (P < .0001) included being African American, an alcohol/substance use disorder, pregnancy, and obesity.

CONCLUSION

Relative to SABA-only therapy, LABA use is associated with a lower risk of ED visit. Certain patients with asthma, such as pregnant women and African Americans, are particularly vulnerable to SAE risk of all types.

Treatment options for the management of exercise-induced asthma and bronchoconstriction

Treatment for exercise-induced bronchospasm and exercise-induced asthma includes both pharmacologic and nonpharmacologic options. Pharmacologic agents that have been proven to be effective for treating these conditions include short- and long-acting β2-adrenoceptor agonists, mast cell-stabilizing agents, anticholinergics, leukotriene receptor antagonists, and inhaled corticosteroids (ICS). When selecting the most appropriate medication, factors to consider include the effectiveness of each, the duration of action, frequency of administration, potential side effects, and tolerance level. Long-acting β2-adrenoceptor agonists should not be used without ICS. Nonpharmacologic treatments include physical conditioning, incorporating a warm-up before and a cool-down period after exercise, performing nasal breathing, avoiding cold weather or environmental allergens, using a face mask or other aid to warm and humidify inhaled air, and modifying dietary intake. The data to support nonpharmacologic treatments are limited; however, they are routinely recommended because of the low risk associated with their use. This article highlights the advantages and limitations of each treatment option.

Both hematopoietic-derived and non-hematopoietic-derived {beta}-arrestin-2 regulates murine allergic airway disease

Allergic asthma, a major cause of morbidity and leading cause of hospitalizations, is an inflammatory disease orchestrated by T helper cells and characterized by the lung migration of eosinophils, which are important asthma effector cells. Lung migration of inflammatory cells requires, among other events, the chemokine receptor transduction of lung-produced inflammatory chemokines. Despite the widespread prevalence of this disease, the molecular mechanisms regulating chemokine production and receptor regulation in asthma are poorly understood. Previous work from our laboratory demonstrated that beta-arrestin-2 positively regulates the development of allergic airway disease in a mouse model, partly through positive regulation of T-lymphocyte chemotaxis to the lung. However, beta-arrestin-2 is expressed in many cell types, including other hematopoietic cells and lung structural cells, which are involved in the development and manifestation of allergic airway disease. To determine the cell types required for beta-arrestin-2-dependent allergic inflammation, we generated bone marrow chimera mice. Using the ovalbumin murine model of allergic airway disease, we show that eosinophilic and lymphocytic inflammation is restored in chimeric mice, with expression of beta-arrestin-2 exclusively on hematopoietic-derived cell types. In contrast, airway hyperresponsiveness is dependent on the expression of beta-arrestin-2 in structural cells. Our data demonstrate that the expression of beta-arrestin-2 in at least two divergent cell types contributes to the pathogenesis of allergic airway disease.

Section 3. A discussion of flexible dosing and patient-centered therapy: highlights of the asthma summit 2009: beyond the guidelines

Despite positive clinical experience and the published clinical benefits of monotherapy with low-or medium-dose inhaled corticosteroids or combination therapy with ICS + long-acting beta-agonist to treat asthma, many patients remain suboptimally controlled. Alternative approaches are needed, and 3 options that have had some success are: 1) using the patient's level of inflammation by established biomarkers to set treatment; 2) self-management incorporating flexible dosing; and 3) using a single inhaler for rescue and maintenance therapy. Which strategy for which patient depends ultimately on the individual patient's disease burden, life-style, comorbidities, preferences, and his or her ability to self-manage the disease, including assessing symptoms and adhering with therapy.

Prostaglandin E2 mediates cough via the EP3 receptor: implications for future disease therapy

RATIONALE

A significant population of patients with severe asthma and chronic obstructive pulmonary disease is less responsive to beta(2)-adrenoceptor agonists and corticosteroids, and there are possible safety issues concerning long-term use of these drugs. Inhaled prostaglandin E(2) (PGE(2)) is antiinflammatory and a bronchodilator in patients with asthma, but it also causes cough.

OBJECTIVES

We aimed to identify the receptor involved in PGE(2)-induced sensory nerve activation and cough using a range of in vitro and in vivo techniques.

METHODS

Depolarization of vagal sensory nerves (human, mouse, and guinea pig) was assessed as an indicator of sensory nerve acitivity. Cough was measured in a conscious guinea pig model.

MEASUREMENTS AND MAIN RESULTS

Using an extensive range of pharmacological tools, we identified that the EP(3) receptor mediates PGE(2)-induced depolarization of sensory nerves in human, mouse, and guinea pig. Further supporting evidence comes from data showing that responses to PGE(2) are virtually abolished in isolated vagus nerves from EP(3)-deficient mice (Ptger3(-/-)). Finally, we demonstrated the role of the EP(3) receptor in vivo using a selective EP(3) antagonist to attenuate PGE(2)-induced cough.

CONCLUSIONS

Identification of the receptor mediating PGE(2)-induced cough represents a key step in developing a drug that is antiinflammatory and a bronchodilator but without unwanted side effects.

Regulation of beta-adrenergic receptor signaling by S-nitrosylation of G-protein-coupled receptor kinase 2

beta-adrenergic receptors (beta-ARs), prototypic G-protein-coupled receptors (GPCRs), play a critical role in regulating numerous physiological processes. The GPCR kinases (GRKs) curtail G-protein signaling and target receptors for internalization. Nitric oxide (NO) and/or S-nitrosothiols (SNOs) can prevent the loss of beta-AR signaling in vivo, but the molecular details are unknown. Here we show in mice that SNOs increase beta-AR expression and prevent agonist-stimulated receptor downregulation; and in cells, SNOs decrease GRK2-mediated beta-AR phosphorylation and subsequent recruitment of beta-arrestin to the receptor, resulting in the attenuation of receptor desensitization and internalization. In both cells and tissues, GRK2 is S-nitrosylated by SNOs as well as by NO synthases, and GRK2 S-nitrosylation increases following stimulation of multiple GPCRs with agonists. Cys340 of GRK2 is identified as a principal locus of inhibition by S-nitrosylation. Our studies thus reveal a central molecular mechanism through which GPCR signaling is regulated.